Sample records for airborne diesel soot

  1. Fragmentation and bond strength of airborne diesel soot agglomerates

    PubMed Central

    Rothenbacher, Sonja; Messerer, Armin; Kasper, Gerhard

    2008-01-01

    Background The potential of diesel soot aerosol particles to break up into smaller units under mechanical stress was investigated by a direct impaction technique which measures the degree of fragmentation of individual agglomerates vs. impact energy. Diesel aerosol was generated by an idling diesel engine used for passenger vehicles. Both the aerosol emitted directly and aerosol that had undergone additional growth by Brownian coagulation ("aging") was investigated. Optionally a thermo-desoption technique at 280°C was used to remove all high-volatility and the majority of low-volatility HC adsorbates from the aerosol before aging. Results It was found that the primary soot agglomerates emitted directly from the engine could not be fragmented at all. Soot agglomerates permitted to grow additionally by Brownian coagulation of the primary emitted particles could be fragmented to a maximum of 75% and 60% respectively, depending on whether adsorbates were removed from their surface prior to aging or not. At most, these aged agglomerates could be broken down to roughly the size of the agglomerates from the primary emission. The energy required for a 50% fragmentation probability of all bonds within an agglomerate was reduced by roughly a factor of 2 when aging "dry" agglomerates. Average bond energies derived from the data were 0.52*10-16 and 1.2*10-16 J, respectively. This is about 2 orders of magnitude higher than estimates for pure van-der-Waals agglomerates, but agrees quite well with other observations. Conclusion Although direct conclusions regarding the behavior of inhaled diesel aerosol in contact with body fluids cannot be drawn from such measurements, the results imply that highly agglomerated soot aerosol particles are unlikely to break up into units smaller than roughly the size distribution emitted as tail pipe soot. PMID:18533015

  2. Nitroaromatic carcinogens in diesel soot: a review of laboratory findings.

    PubMed Central

    Wei, E T; Shu, H P

    1983-01-01

    The automobile industry plans to increase production of diesel-powered passenger cars because diesel engines provide better fuel economy than conventional gasoline engines. Diesel engines, however, produce more soot, and increased use of diesel cars will result in more discharge of diesel soot into the atmosphere. Recently, a new class of chemicals, called nitroaromatic compounds, have been identified in chemical extracts of diesel soot. Some of these nitroaromatic compounds produce mutations when tested in in vitro bacterial and mammalian cell assays, and cancer when tested in animals. Here, we review the relevance of these new laboratory findings to current deliberations over emission standards for particles from diesel cars. PMID:6192732

  3. Characterization of Diesel Soot Aggregates by Scattering and Extinction Methods

    NASA Astrophysics Data System (ADS)

    Kamimoto, Takeyuki

    2006-07-01

    Characteristics of diesel soot particles sampled from diesel exhaust of a common-rail turbo-charged diesel engine are quantified by scattering and extinction diagnostics using newly build two laser-based instruments. The radius of gyration representing the aggregates size is measured by the angular distribution of scattering intensity, while the soot mass concentration is measured by a two-wavelength extinction method. An approach to estimate the refractive index of diesel soot by an analysis of the extinction and scattering data using an aggregates scattering theory is proposed.

  4. Morphology and nano-structure analysis of soot particles sampled from high pressure diesel jet flames under diesel-like conditions

    NASA Astrophysics Data System (ADS)

    Jiang, Hao; Li, Tie; Wang, Yifeng; He, Pengfei

    2018-04-01

    Soot particles emitted from diesel engines have a significant impact on the atmospheric environment. Detailed understanding of soot formation and oxidation processes is helpful for reducing the pollution of soot particles, which requires information such as the size and nano-structure parameters of the soot primary particles sampled in a high-temperature and high-pressure diesel jet flame. Based on the thermophoretic principle, a novel sampling probe minimally disturbing the diesel jet flame in a constant volume combustion vessel is developed for analysing soot particles. The injected quantity of diesel fuel is less than 10 mg, and the soot particles sampled by carriers with a transmission electron microscope (TEM) grid and lacey TEM grid can be used to analyse the morphologies of soot aggregates and the nano-structure of the soot primary particles, respectively. When the quantity of diesel fuel is more than 10 mg, in order to avoid burning-off of the carriers in higher temperature and pressure conditions, single-crystal silicon chips are employed. Ultrasonic oscillations and alcohol extraction are then implemented to obtain high quality soot samples for observation using a high-resolution transmission electron microscope. An in-house Matlab-based code is developed to extract the nano-structure parameters of the soot particles. A complete sampling and analysis procedure of the soot particles is provided to study the formation and oxidation mechanism of soot.

  5. Reducing Soot in Diesel Exhaust

    NASA Technical Reports Server (NTRS)

    Bellan, J.

    1984-01-01

    Electrically charged fuel improves oxidation. Fuel injection system reduces amount of soot formed in diesel engines. Spray injector electrically charges fuel droplets as they enter cylinder. Charged droplets repel each other, creating, dilute fuel mist easily penetrated by oxygen in cylinder.

  6. Understanding the difference in oxidative properties between flame and diesel soot nanoparticles: the role of metals.

    PubMed

    Kim, S H; Fletcher, R A; Zachariah, M R

    2005-06-01

    The purpose of this paper is to address the differences observed in the oxidative kinetics between flame and diesel derived soots. In particular, it has been observed that flame soot has a significantly higher activation energy for oxidation than does diesel soot. The hypothesis tested in this paper is that metals, possibly coming from lubricating oils, within diesel generated soot particles may be responsible for this effect. This is supported by the fact that addition of metal additives to diesel fuel is shown to have no effect on the activation energy of soot oxidation. The subject of this paper lies in testing the hypothesis by adding metal directly to a flame and extracting oxidation kinetics. Using a high temperature oxidation tandem differential mobility analyzer (HTO-TDMA) we extract particle size dependent kinetics for the oxidation of flame-derived soot doped with and without iron. We found that indeed addition of iron to a flame reduced the activation energy significantly from approximately 162 +/- 3 kJ/mol to approximately 116 +/- 3 kJ/mol, comparable with diesel engine generated soot with an activation energy approximately 110 kJ/mol. These results are consistent with the idea that small quantities of metals during diesel combustion may play an important role in soot abatement.

  7. An investigation of late-combustion soot burnout in a DI diesel engine using simultaneous planar imaging of soot and OH radical

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    John E. Dec; Peter L. Kelly-Zion

    Diesel engine design continues to be driven by the need to improve performance while at the same time achieving further reductions in emissions. The development of new designs to accomplish these goals requires an understanding of how the emissions are produced in the engine. Laser-imaging diagnostics are uniquely capable of providing this information, and the understanding of diesel combustion and emissions formation has been advanced considerably in recent years by their application. However, previous studies have generally focused on the early and middle stages of diesel combustion. These previous laser-imaging studies do provide important insight into the soot formation andmore » oxidation processes during the main combustion event. They indicate that prior to the end of injection, soot formation is initiated by fuel-rich premixed combustion (equivalence ratio > 4) near the upstream limit of the luminous portion of the reacting fuel jet. The soot is then oxidized at the diffusion flame around the periphery of the luminous plume. Under typical diesel engine conditions, the diffusion flame does not burn the remaining fuel and soot as rapidly as it is supplied, resulting in an expanding region of rich combustion products and soot. This is evident in natural emission images by the increasing size of the luminous soot cloud prior to the end of injection. Hence, the amount of soot in the combustion chamber typically increases until shortly after the end of fuel injection, at which time the main soot formation period ends and the burnout phase begins. Sampling valve and two-color pyrometry data indicate that the vast majority (more than 90%) of the soot formed is oxidized before combustion ends; however, it is generally thought that a small fraction of this soot from the main combustion zones is not consumed and is the source of tail pipe soot emissions.« less

  8. Blue light emitting diesel soot for photonic applications

    NASA Astrophysics Data System (ADS)

    Swapna, M. S.; Sankararaman, S.

    2018-01-01

    The present work is the first report of producing blue light emission from phosphor free and low-cost material—the diesel soot from the internal combustion engines (ICEs). The structural morphology is analyzed by field emission scanning electron microscopy and high-resolution transmission electron microscopy. The optical characterization is done by recording UV-visible spectrum and photoluminescent Spectrum. The CIE plot and the power spectrum for the sample show blue emission. This is further verified by collecting diesel soot from the ICE of different year of make. A visual confirmation of blue emission is obtained by exciting the sample with UV laser. The presence of various allotropic forms of carbon in the sample is identified by x-ray diffraction, Fourier transform infrared and Raman spectroscopic analysis.

  9. X-ray scattering and spectroscopy studies on diesel soot from oxygenated fuel under various engine load conditions

    USGS Publications Warehouse

    Braun, Andreas; Shah, N.; Huggins, Frank E.; Kelly, K.E.; Sarofim, A.; Jacobsen, C.; Wirick, S.; Francis, H.; Ilavsky, J.; Thomas, G.E.; Huffman, G.P.

    2005-01-01

    Diesel soot from reference diesel fuel and oxygenated fuel under idle and load engine conditions was investigated with X-ray scattering and X-ray carbon K-edge absorption spectroscopy. Up to five characteristic size ranges were found. Idle soot was generally found to have larger primary particles and aggregates but smaller crystallites, than load soot. Load soot has a higher degree of crystallinity than idle soot. Adding oxygenates to diesel fuel enhanced differences in the characteristics of diesel soot, or even reversed them. Aromaticity of idle soot from oxygenated diesel fuel was significantly larger than from the corresponding load soot. Carbon near-edge X-ray absorption fine structure (NEXAFS) spectroscopy was applied to gather information about the presence of relative amounts of carbon double bonds (CC, CO) and carbon single bonds (C-H, C-OH, COOH). Using scanning X-ray transmission microspectroscopy (STXM), the relative amounts of these carbon bond states were shown to vary spatially over distances approximately 50 to 100 nm. The results from the X-ray techniques are supported by thermo-gravimetry analysis and high-resolution transmission electron microscopy. ?? 2005 Elsevier Ltd. All rights reserved.

  10. Ice nucleation activity of diesel soot particles at cirrus relevant temperature conditions: Effects of hydration, secondary organics coating, soot morphology, and coagulation

    NASA Astrophysics Data System (ADS)

    Kulkarni, Gourihar; China, Swarup; Liu, Shang; Nandasiri, Manjula; Sharma, Noopur; Wilson, Jacqueline; Aiken, Allison C.; Chand, Duli; Laskin, Alexander; Mazzoleni, Claudio; Pekour, Mikhail; Shilling, John; Shutthanandan, Vaithiyalingam; Zelenyuk, Alla; Zaveri, Rahul A.

    2016-04-01

    Ice formation by diesel soot particles was investigated at temperatures ranging from -40 to -50°C. Size-selected soot particles were physically and chemically aged in an environmental chamber, and their ice nucleating properties were determined using a continuous flow diffusion type ice nucleation chamber. Bare (freshly formed), hydrated, and compacted soot particles, as well as α-pinene secondary organic aerosol (SOA)-coated soot particles at high relative humidity conditions, showed ice formation activity at subsaturation conditions with respect to water but below the homogeneous freezing threshold conditions. However, SOA-coated soot particles at dry conditions were observed to freeze at homogeneous freezing threshold conditions. Overall, our results suggest that heterogeneous ice nucleation activity of freshly emitted diesel soot particles are sensitive to some of the aging processes that soot can undergo in the atmosphere.

  11. Comparative Study of Different Methods for Soot Sensing and Filter Monitoring in Diesel Exhausts.

    PubMed

    Feulner, Markus; Hagen, Gunter; Hottner, Kathrin; Redel, Sabrina; Müller, Andreas; Moos, Ralf

    2017-02-18

    Due to increasingly tighter emission limits for diesel and gasoline engines, especially concerning particulate matter emissions, particulate filters are becoming indispensable devices for exhaust gas after treatment. Thereby, for an efficient engine and filter control strategy and a cost-efficient filter design, reliable technologies to determine the soot load of the filters and to measure particulate matter concentrations in the exhaust gas during vehicle operation are highly needed. In this study, different approaches for soot sensing are compared. Measurements were conducted on a dynamometer diesel engine test bench with a diesel particulate filter (DPF). The DPF was monitored by a relatively new microwave-based approach. Simultaneously, a resistive type soot sensor and a Pegasor soot sensing device as a reference system measured the soot concentration exhaust upstream of the DPF. By changing engine parameters, different engine out soot emission rates were set. It was found that the microwave-based signal may not only indicate directly the filter loading, but by a time derivative, the engine out soot emission rate can be deduced. Furthermore, by integrating the measured particulate mass in the exhaust, the soot load of the filter can be determined. In summary, all systems coincide well within certain boundaries and the filter itself can act as a soot sensor.

  12. Comparative Study of Different Methods for Soot Sensing and Filter Monitoring in Diesel Exhausts

    PubMed Central

    Feulner, Markus; Hagen, Gunter; Hottner, Kathrin; Redel, Sabrina; Müller, Andreas; Moos, Ralf

    2017-01-01

    Due to increasingly tighter emission limits for diesel and gasoline engines, especially concerning particulate matter emissions, particulate filters are becoming indispensable devices for exhaust gas after treatment. Thereby, for an efficient engine and filter control strategy and a cost-efficient filter design, reliable technologies to determine the soot load of the filters and to measure particulate matter concentrations in the exhaust gas during vehicle operation are highly needed. In this study, different approaches for soot sensing are compared. Measurements were conducted on a dynamometer diesel engine test bench with a diesel particulate filter (DPF). The DPF was monitored by a relatively new microwave-based approach. Simultaneously, a resistive type soot sensor and a Pegasor soot sensing device as a reference system measured the soot concentration exhaust upstream of the DPF. By changing engine parameters, different engine out soot emission rates were set. It was found that the microwave-based signal may not only indicate directly the filter loading, but by a time derivative, the engine out soot emission rate can be deduced. Furthermore, by integrating the measured particulate mass in the exhaust, the soot load of the filter can be determined. In summary, all systems coincide well within certain boundaries and the filter itself can act as a soot sensor. PMID:28218700

  13. Comparison of the tribology performance of nano-diesel soot and graphite particles as lubricant additives

    NASA Astrophysics Data System (ADS)

    Zhang, Zu-chuan; Cai, Zhen-bing; Peng, Jin-fang; Zhu, Min-hao

    2016-02-01

    The tribology behavior of exhaust diesel soot as a lubricant additive was investigated and then compared with that of a selection of commercial nano-graphite particles. Specifically, 0.01 wt% particles were dispersed in PAO4 oil with 1 wt% sorbitan monooleate (Span 80) as a dispersing agent, and wear tests based on the ball against plate mode were conducted at various temperatures. Different analytical techniques (e.g. transmission electron, scanning electron and infrared microscopy; energy dispersive x-ray and Raman spectroscopy; and charge measurement) were employed to characterize the chemistry and morphology of the additives and their tribology performance. The oil containing only 0.01 wt% diesel soot clearly improved wear resistance over 60 °C. In particular, at 100 °C the wear rate decreased by approximately 90% compared to the function of base oil. In the same test conditions, diesel soot exhibited better anti-wear performance than nano-graphite at high temperatures. The potential measure showed that the nano-graphite had positive charge and the diesel soot had negative charge. Electrochemical action may play an important role in the lubricant mechanisms of diesel soot and graphite as oil additives.

  14. Evolution of In-Cylinder Diesel Engine Soot and Emission Characteristics Investigated with Online Aerosol Mass Spectrometry.

    PubMed

    Malmborg, V B; Eriksson, A C; Shen, M; Nilsson, P; Gallo, Y; Waldheim, B; Martinsson, J; Andersson, Ö; Pagels, J

    2017-02-07

    To design diesel engines with low environmental impact, it is important to link health and climate-relevant soot (black carbon) emission characteristics to specific combustion conditions. The in-cylinder evolution of soot properties over the combustion cycle and as a function of exhaust gas recirculation (EGR) was investigated in a modern heavy-duty diesel engine. A novel combination of a fast gas-sampling valve and a soot particle aerosol mass spectrometer (SP-AMS) enabled online measurements of the in-cylinder soot chemistry. The results show that EGR reduced the soot formation rate. However, the late cycle soot oxidation rate (soot removal) was reduced even more, and the net effect was increased soot emissions. EGR resulted in an accumulation of polycyclic aromatic hydrocarbons (PAHs) during combustion, and led to increased PAH emissions. We show that mass spectral and optical signatures of the in-cylinder soot and associated low volatility organics change dramatically from the soot formation dominated phase to the soot oxidation dominated phase. These signatures include a class of fullerene carbon clusters that we hypothesize represent less graphitized, C 5 -containing fullerenic (high tortuosity or curved) soot nanostructures arising from decreased combustion temperatures and increased premixing of air and fuel with EGR. Altered soot properties are of key importance when designing emission control strategies such as diesel particulate filters and when introducing novel biofuels.

  15. Determination of light extinction efficiency of diesel soot from smoke opacity measurements

    NASA Astrophysics Data System (ADS)

    Lapuerta, Magín; Martos, Francisco J.; Cárdenas, M. Dolores

    2005-10-01

    An experimental method for the indirect determination of the light extinction efficiency of the exhaust gas emitted by diesel engines is proposed in this paper, based on the simultaneous measurement of spot opacity and continuous opacity, together with the double modelling of the associated soot concentration. The first model simulates the projection of a differently sized soot particle population enclosed in an exhaust gas sample on the filter of a spot opacimeter. The second one simulates the light extinction caused by the soot particles flowing in the exhaust gas stream in an online continuous opacimeter, on the basis of the Beer-Lambert law. This method is an alternative to other theoretical or semi-empirical complex methods which have proved to be inadequate in the case of soot agglomerates. The application of this method to a set of experimental smoke measurements from a commercial light-duty DI diesel engine typical of vehicle road transportation permitted us to draw conclusions about the effect of different engine conditions on the mean light extinction efficiency of the soot particles flowing in the raw exhaust gas stream.

  16. Bulk and surface structural investigations of diesel engine soot and carbon black.

    PubMed

    Müller, J-O; Su, D S; Wild, U; Schlögl, R

    2007-08-14

    The microstructure and electronic structure of environmentally relevant carbons such as Euro IV heavy duty diesel engine soot, soot from a black smoking diesel engine, spark discharge soot as model aerosol, commercial furnace soot and lamp black are investigated by transmission electron microscopy, electron energy-loss spectroscopy and X-ray photoelectron spectroscopy. The materials exhibit differences in the predominant bonding, which influences microstructure as well as surface functionalization. These chemical and physical properties depend on the formation history of the investigated carbonaceous materials. In this work, a correlation of the microstructure of the samples to the predominant bonding and incorporation of oxygen into the carbons is obtained. It is shown that a high amount of defects and the deviation of the carbons from a perfect graphitic structure results in a increased incorporation of oxygen and hydrogen. A correlation between the length and curvature of graphene layers with the bonding state of carbon atoms and incorporation of oxygen and hydrogen is established.

  17. Ignition and early soot formation in a DI diesel engine using multiple 2-D imaging diagnostics

    NASA Astrophysics Data System (ADS)

    Dec, John E.; Espey, Christoph

    Combined optical imaging diagnostics in the fuel jet of a direct-injection diesel engine to study the ignition and early soot formation processes. A diesel engine of the 'heavy-duty' size class was operated at a representative medium speed (1200 rpm) operating condition. Two fuels were used, a 42.5 cetane number mixture of the diesel reference fuels and a new low-sooting fuel. Combustion and soot formation are almost identical for both fuels. Ignition and early combustion were studied by imaging the natural chemiluminescence using a calibrated intensified video camera. Early soot development was investigated via luminosity imaging and simultaneous planar imaging of laser-induced incandescence (LII) and elastic scattering. The latter provide relative soot concentrations and particle size distributions. Data show that ignition occurs at multiple points across the downstream region of all the fuel jets prior to first apparent heat release well before any soot luminosity occurs. Quantitative vapor-fuel/air mixture images in the leading portion of the jet are also presented and discussed with respect to the early combustion data. The first soot occurs at random locations, and shortly thereafter, small soot particles develop throughout the cross section of the leading portion of the jet. Data indicate that this soot arises from the fuel-rich premixed burn. Then, significantly larger soot particles appear around the periphery of the jet, presumably from the initial diffusion combustion. By the end of the premixed burn, the soot has developed a distribution pattern of a higher concentration toward the front of the jet and a lower concentration upstream, with the larger-sized soot particles being generally confined to the periphery of the jet.

  18. Chemical characterization of diesel and hydrotreated vegetable oil (HVO) soot after reactive gas probing using diffuse reflectance FTIR spectroscopy (DRIFTS).

    PubMed

    Tapia, A; Salgado, M S; Martín, M P; Rodríguez-Fernández, J; Rossi, M J; Cabañas, B

    2017-03-01

    A chemical characterization of diesel and hydrotreated vegetable oil (HVO) soot has been developed using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) before and after the reaction with different probe gases. Samples were generated under combustion conditions corresponding to an urban operation mode of a diesel engine and were reacted with probe gas-phase molecules in a Knudsen flow reactor. Specifically, NH 2 OH, O 3 and NO 2 were used as reactants (probes) and selected according to their reactivities towards specific functional groups on the sample surface. Samples of previously ground soot were diluted with KBr and were introduced in a DRIFTS accessory. A comparison between unreacted and reacted soot samples was made in order to establish chemical changes on the soot surface upon reaction. It was concluded that the interface of diesel and HVO soot before reaction mainly consists polycyclic aromatic hydrocarbons, nitro and carbonyl compounds, as well as ether functionalities. The main difference between both soot samples was observed in the band of the C=O groups that in diesel soot was observed at 1719 cm -1 but not in HVO soot. After reaction with probe gases, it was found that nitro compounds remain on the soot surface, that the degree of unsaturation decreases for reacted samples, and that new spectral bands such as hydroxyl groups are observed.

  19. Oxidation of diesel soot on binary oxide CuCr(Co)-based monoliths.

    PubMed

    Soloviev, Sergiy O; Kapran, Andriy Y; Kurylets, Yaroslava P

    2015-02-01

    Binary oxide systems (CuCr2O4, CuCo2O4), deposited onto cordierite monoliths of honeycomb structure with a second support (finely dispersed Al2O3), were prepared as filters for catalytic combustion of diesel soot using internal combustion engine's gas exhausts (O2, NOx, H2O, CO2) and O3 as oxidizing agents. It is shown that the second support increases soot capacity of aforementioned filters, and causes dispersion of the particles of spinel phases as active components enhancing thereby catalyst activity and selectivity of soot combustion to CO2. Oxidants used can be arranged with reference to decreasing their activity in a following series: O3≫NO2>H2O>NO>O2>CO2. Ozone proved to be the most efficient oxidizing agent: the diesel soot combustion by O3 occurs intensively (in the presence of copper chromite based catalyst) even at closing to ambient temperatures. Results obtained give a basis for the conclusion that using a catalytic coating on soot filters in the form of aforementioned binary oxide systems and ozone as the initiator of the oxidation processes is a promising approach in solving the problem of comprehensive purification of automotive exhaust gases at relatively low temperatures, known as the "cold start" problem. Copyright © 2014. Published by Elsevier B.V.

  20. Aggregation Kinetics of Diesel Soot Nanoparticles in Wet Environments.

    PubMed

    Chen, Chengyu; Huang, Weilin

    2017-02-21

    Soot produced during incomplete combustion consists mainly of carbonaceous nanoparticles (NPs) with severe adverse environmental and health effects, and its environmental fate and transport are largely controlled by aggregation. In this study, we examined the aggregation behavior for diesel soot NPs under aqueous condition in an effort to elucidate the fundamental processes that govern soot particle-particle interactions in wet environments such as rain droplets or surface aquatic systems. The influence of electrolytes and aqueous pH on colloidal stability of these NPs was investigated by measuring their aggregation kinetics in different aqueous solution chemistries. The results showed that the NPs had negatively charged surfaces and exhibited both reaction- and diffusion-limited aggregation regimes with rates depended upon solution chemistry. The aggregation kinetics data were in good agreement with the classic Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. The critical coagulation concentrations (CCC) were quantified and the Hamaker constant was derived for the soot (1.4 × 10 -20 J) using the colloidal chemistry approach. The study indicated that, depending upon local aqueous chemistry, single soot NPs could remain stable against self-aggregation in typical freshwater environments and in neutral cloud droplets but are likely to aggregate under salty (e.g., estuaries) or acidic (e.g., acid rain droplets) aquatic conditions or both.

  1. Ice nucleation activity of diesel soot particles at Cirrus relevant conditions: Effects of hydration, secondary organics coating, hydration, soot morphology, and coagulation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kulkarni, Gourihar R.; China, Swarup; Liu, Shang

    The role of atmospheric relevant soot particles that are processed in the atmosphere toward ice nucleation at cirrus cloud condition is poorly understood. In this study, the ice nucleating properties of diesel soot particles subjected to various physical and chemical aging treatments were investigated at temperatures ranging from -40 to -50 °C. We show that bare soot particles nucleate ice in deposition mode, but coating with secondary organics suppresses the heterogeneous ice nucleation potential of soot particles requiring homogeneous freezing threshold conditions. However, the ice nucleation efficiency of soot particles coated with an aqueous organic layer was similar to baremore » soot particles. Hydration of bare soot particles slightly enhanced the ice nucleation efficiency, and the IN abilities of compact soot particles (roundness = ~ 0.6) were similar to bare lacey soot particles (roundness = ~ 0.4). These results indicate that ice nucleation properties are sensitive to the various aging treatments.« less

  2. REDUCING DIESEL NOX AND SOOT EMISSIONS VIA PARTICLE-FREE EXHAUST GAS RECIRCULATION - PHASE I

    EPA Science Inventory

    Diesel engines play an important role in the United States economy for power generation and transportation. However, NOx and soot emissions from both stationary and mobile diesel engines are a major contributor to air pollution. Many engine modifications and exhaust-after-t...

  3. Controlling soot formation with filtered EGR for diesel and biodiesel fuelled engines.

    PubMed

    Gill, S S; Turner, D; Tsolakis, A; York, A P E

    2012-04-03

    Although exhaust gas recirculation (EGR) is an effective strategy for controlling the levels of nitrogen oxides (NO(X)) emitted from a diesel engine, the full potential of EGR in NO(X)/PM trade-off and engine performance (i.e., fuel economy) has not fully been exploited. Significant work into the cause and control of particulate matter (PM) has been made over the past decade with new cleaner fuels and after-treatment devices emerging to comply with the current and forthcoming emission regulations. In earlier work, we demonstrated that engine operation with oxygenated fuels (e.g., biodiesel) reduces the PM emissions and extends the engine tolerance to EGR before it reaches smoke-limited conditions. The same result has also been reported when high cetane number fuels such as gas-to-liquid (GTL) are used. To further our understanding of the relationship between EGR and PM formation, a diesel particulate filter (DPF) was integrated into the EGR loop to filter the recirculated soot particulates. The control of the soot recirculation penalty through filtered EGR (FEGR) resulted in a 50% engine-out soot reduction, thus showing the possibility of extending the maximum EGR limit or being able to run at the same level of EGR with an improved NO(X)/soot trade-off.

  4. Further theoretical studies of modified cyclone separator as a diesel soot particulate emission arrester.

    PubMed

    Mukhopadhyay, N; Bose, P K

    2009-10-01

    Soot particulate emission reduction from diesel engine is one of the most emerging problems associated with the exhaust pollution. Diesel particulate filters (DPF) hold out the prospects of substantially reducing regulated particulate emissions but the question of the reliable regeneration of filters still remains a difficult hurdle to overcome. Many of the solutions proposed to date suffer from design complexity, cost, regeneration problem and energy demands. This study presents a computer aided theoretical analysis for controlling diesel soot particulate emission by cyclone separator--a non contact type particulate removal system considering outer vortex flow, inner vortex flow and packed ceramic fiber filter at the end of vortex finder tube. Cyclone separator with low initial cost, simple construction produces low back pressure and reasonably high collection efficiencies with reduced regeneration problems. Cyclone separator is modified by placing a continuous ceramic packed fiber filter placed at the end of the vortex finder tube. In this work, the grade efficiency model of diesel soot particulate emission is proposed considering outer vortex, inner vortex and the continuous ceramic packed fiber filter. Pressure drop model is also proposed considering the effect of the ceramic fiber filter. Proposed model gives reasonably good collection efficiency with permissible pressure drop limit of diesel engine operation. Theoretical approach is predicted for calculating the cut size diameter considering the effect of Cunningham molecular slip correction factor. The result shows good agreements with existing cyclone and DPF flow characteristics.

  5. Carbon Nanostructure of Diesel Soot Particles Emitted from 2 and 4 Stroke Marine Engines Burning Different Fuels.

    PubMed

    Lee, Won-Ju; Park, Seul-Hyun; Jang, Se-Hyun; Kim, Hwajin; Choi, Sung Kuk; Cho, Kwon-Hae; Cho, Ik-Soon; Lee, Sang-Min; Choi, Jae-Hyuk

    2018-03-01

    Diesel soot particles were sampled from 2-stroke and 4-stroke engines that burned two different fuels (Bunker A and C, respectively), and the effects of the engine and fuel types on the structural characteristics of the soot particle were analyzed. The carbon nanostructures of the sampled particles were characterized using various techniques. The results showed that the soot sample collected from the 4-stroke engine, which burned Bunker C, has a higher degree of order of the carbon nanostructure than the sample collected from the 2-stroke engine, which burned Bunker A. Furthermore, the difference in the exhaust gas temperatures originating from the different engine and fuel types can affect the nanostructure of the soot emitted from marine diesel engines.

  6. Simulation on Soot Oxidation with NO2 and O2 in a Diesel Particulate Filter

    NASA Astrophysics Data System (ADS)

    Yamamoto, Kazuhiro; Satake, Shingo; Yamashita, Hiroshi; Obuchi, Akira; Uchisawa, Junko

    Although diesel engines have an advantage of low fuel consumption in comparison with gasoline engines, exhaust gas has more particulate matters (PM) including soot. As one of the key technologies, a diesel particulate filter (DPF) has been developed to reduce PM. When the exhaust gas passes its porous filter wall, the soot particles are trapped. However, the filter would readily be plugged with particles, and the accumulated particles must be removed to prevent filter clogging and a rise in backpressure, which is called filter regeneration process. In this study, we have simulated the flow in the wall-flow DPF using the lattice Boltzmann method. Filters of different length, porosity, and pore size are used. The soot oxidation for filter regeneration process is considered. Especially, the effect of NO2 on the soot oxidation is examined. The reaction rate has been determined by previous experimental data. Results show that, the flow along the filter monolith is roughly uniform, and the large pressure drop across the filter wall is observed. The soot oxidation rate becomes ten times larger when NO2 is added. These are useful information to construct the future regeneration system.

  7. Method for removing soot from exhaust gases

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Suib, Steven L.; Dharmarathna, D. A. Saminda; Pahalagedara, Lakshitha R.

    A method for oxidizing soot from diesel exhaust gas from a diesel engine. The method involves providing a diesel particulate filter for receiving the diesel exhaust gas; coating a catalyst composition on the diesel particulate filter; and contacting the soot from the diesel exhaust gas with the catalyst coated diesel particulate filter at a temperature sufficient to oxidize the soot to carbon dioxide. The catalyst composition is a doped or undoped manganese oxide octahedral molecular sieve (OMS-2) material. A diesel exhaust gas treatment system that includes a diesel particulate filter for receiving diesel exhaust gas from a diesel engine andmore » collecting soot; and a catalyst composition coated on the diesel particulate filter. The catalyst composition is a doped or undoped manganese oxide octahedral molecular sieve (OMS-2).« less

  8. Effect of intrinsic organic carbon on the optical properties of fresh diesel soot

    PubMed Central

    Adler, Gabriella; Riziq, Ali Abo; Erlick, Carynelisa; Rudich, Yinon

    2010-01-01

    This study focuses on the retrieval of the normalized mass absorption cross section (MAC) of soot using theoretical calculations that incorporate new measurements of the optical properties of organic carbon (OC) intrinsic to fresh diesel soot. Intrinsic OC was extracted by water and an organic solvent, and the complex refractive index of the extracted OC was derived at 532 and 355-nm wavelengths using cavity ring-down aerosol spectrometry. The extracted OC was found to absorb weakly in the visible wavelengths and moderately at blue wavelengths. The mass ratio of OC and elemental carbon (EC) in the collected particles was evaluated using a thermo-optical method. The measured EC/OC ratio in the soot exhibited substantial variability from measurement to measurement, ranging between 2 and 5. To test the sensitivity of the MAC to this variability, three different EC/OC ratios (2∶1, 1∶1, and 1∶2) were chosen as representative. Particle size and spherule morphology were estimated using scanning electron microscopy, and the soot was found to be primarily in the form of aggregates with a dominant aggregate diameter mode in the range 200–250 nm. The measured refractive index of the extracted OC was used with a variety of theoretical models to calculate the MAC of internally mixed diesel soot at 532 and 355 nm. We conclude that Rayleigh–Debye–Gans theory on clusters of coated spherules and T-matrix of a solid EC spheroid coated by intrinsic OC are both consistent with previous measurements; however, Rayleigh–Debye–Gans theory provides a more realistic physical model for the calculation PMID:20018649

  9. The impact of carbon dioxide and exhaust gas recirculation on the oxidative reactivity of soot from ethylene flames and diesel engines

    NASA Astrophysics Data System (ADS)

    Al-Qurashi, Khalid O.

    Restrictive emissions standards to reduce nitrogen oxides (NOx) and particulate matter (PM) emissions from diesel engines necessitate the development of advanced emission control technology. The engine manufacturers in the United States have implemented the exhaust gas recirculation (EGR) and diesel particulate filters (DPF) to meet the stringent emissions limits on NOx and PM, respectively. Although the EGR-DPF system is an effective means to control diesel engine emissions, there are some concerns associated with its implementation. The chief concern with this system is the DPF regenerability, which depends upon several factors, among which are the physicochemical properties of the soot. Despite the plethora of research that has been conducted on DPF regenerability, the impact of EGR on soot reactivity and DPF regenerability is yet to be examined. This work concerns the impact of EGR on the oxidative reactivity of diesel soot. It is part of ongoing research to bridge the gap in establishing a relationship between soot formation conditions, properties, and reactivity. This work is divided into three phases. In the first phase, carbon dioxide (CO2) was added to the intake charge of a single cylinder engine via cylinders of compressed CO2. This approach simulates the cold-particle-free EGR. The results showed that inclusion of CO2 changes the soot properties and yields synergistic effects on the oxidative reactivity of the resulting soot. The second phase of this research was motivated by the findings from the first phase. In this phase, post-flame ethylene soot was produced from a laboratory co-flow laminar diffusion flame to better understand the mechanism by which the CO2 affects soot reactivity. This phase was accomplished by successfully isolating the dilution, thermal, and chemical effects of the CO2. The results showed that all of these effects account for a measurable increase in soot reactivity. Nevertheless, the thermal effect was found to be the most

  10. Experimental and theoretical study of diesel soot reactivity

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Marcuccilli, F; Gilot, P.; Stanmore, B.

    1994-12-31

    In order to provide data for modelling the performance of a regenerative soot filter, a study of the oxidation kinetics of diesel soot in the temperature range from 600 C to 800 C was undertaken. Isothermal burning rates at a number of temperatures were measured in rectangular soot beds within a thermobalance. The technique was easy to use, but the combustion rate was found to depend on bed mass. The oxidation process was thus limited by mass transfer effects. A two-dimensional mathematical model of oxygen transfer was developed to extract the true kinetic rates from experimental data. The two-dimensional approachmore » was required because significant oxygen depletion occurred along both axes. Using assumed kinetic rates, oxygen concentration profiles in the gas phase above the bed and within the bed were calculated. The true kinetics at a number of temperatures were, then established by matching predicted oxygen consumption with measured consumption. Application of the model required values of the effective diffusion coefficient for oxygen within the bed. Accordingly, the structure and properties of the soot aggregates were determined. A supplements study was carried out to identify the appropriate primary reaction products. The measured kinetic rates were then used in a simpler, monodimensional model to evaluate the mean oxygen mass transfer coefficients to the surface of the bed. The results show that burning below about 730 C is in regime 1 and can be described by K = 6.9 {times} 10{sup 12} exp ({minus}207,000/RT) (s{sup {minus}1}) with R = 8.314 J/mol {times} K. Above, 730 C, there is a decrease in apparent activation energy, probably due to thermal ``annealing,`` which changes the microstructure of the carbon. As a result, the inherent reactivity declines and/or the bed becomes less accessible to oxygen.« less

  11. Morphology of diesel soot residuals from supercooled water droplets and ice crystals: Implications for optical properties

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    China, Swarup; Kulkarni, Gourihar; Scarnato, Barbara V.

    Freshly emitted soot particles are fractal-like aggregates, but atmospheric processing often transforms their morphology. Morphology of soot particles plays an important role in determining their optical properties, life cycle and hence their effect on Earth’s radiative balance. However, little is known about the morphology of soot particles that participated in cold cloud processes. Here we report results from laboratory experiments that simulate cold cloud processing of diesel soot particles by allowing them to form supercooled droplets and ice crystals at -20 and -40°C, respectively. Electron microscopy revealed that soot residuals from ice crystals were more compact (roundness~0.55) than those frommore » supercooled droplets (roundness ~0.45), while nascent soot particles were the least compact (roundness~0.41). Optical simulations using the discrete dipole approximation showed that the more compact structure enhances soot single scattering albedo by a factor up to 1.4, thereby reducing the top-of-the-atmosphere direct radiative forcing by ~63%. Lastly, these results underscore that climate models should consider the morphological evolution of soot particles due to cold cloud processing to improve the estimate of direct radiative forcing of soot.« less

  12. Morphology of diesel soot residuals from supercooled water droplets and ice crystals: Implications for optical properties

    DOE PAGES

    China, Swarup; Kulkarni, Gourihar; Scarnato, Barbara V.; ...

    2015-11-01

    Freshly emitted soot particles are fractal-like aggregates, but atmospheric processing often transforms their morphology. Morphology of soot particles plays an important role in determining their optical properties, life cycle and hence their effect on Earth’s radiative balance. However, little is known about the morphology of soot particles that participated in cold cloud processes. Here we report results from laboratory experiments that simulate cold cloud processing of diesel soot particles by allowing them to form supercooled droplets and ice crystals at -20 and -40°C, respectively. Electron microscopy revealed that soot residuals from ice crystals were more compact (roundness~0.55) than those frommore » supercooled droplets (roundness ~0.45), while nascent soot particles were the least compact (roundness~0.41). Optical simulations using the discrete dipole approximation showed that the more compact structure enhances soot single scattering albedo by a factor up to 1.4, thereby reducing the top-of-the-atmosphere direct radiative forcing by ~63%. Lastly, these results underscore that climate models should consider the morphological evolution of soot particles due to cold cloud processing to improve the estimate of direct radiative forcing of soot.« less

  13. Atomic layer deposition of cerium oxide for potential use in diesel soot combustion

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ivanova, Tatiana V., E-mail: tatiana.ivanova@lut.fi, E-mail: ivanova.tatyana.v@gmail.com; Toivonen, Jenni; Maydannik, Philipp S.

    The particulate soot emission from diesel motors has a severe impact on the environment and people's health. The use of catalytic convertors is one of the ways to minimize the emission and decrease the hazard level. In this paper, the activity of cerium oxide for catalytic combustion of diesel soot was studied. Thin films of cerium dioxide were synthesized by atomic layer deposition using tetrakis(2,2,6,6-tetramethyl-3,5-heptanedionato)cerium [Ce(thd){sub 4}] and ozone as precursors. The characteristics of the films were studied as a function of deposition conditions within the reaction temperature range of 180–350 °C. Thickness, crystallinity, elemental composition, and morphology of the CeO{submore » 2} films deposited on Si (100) were characterized by ellipsometry, x-ray diffraction, x-ray photoelectron spectroscopy, atomic force microscopy, and field emission scanning electron microscopy, respectively. The growth rate of CeO{sub 2} was observed to be 0.30 Å/cycle at temperatures up to 250 °C with a slight increase to 0.37 Å/cycle at 300 °C. The effect of CeO{sub 2} films grown on stainless steel foil supports on soot combustion was measured with annealing tests. Based on the analysis of these, in catalytic applications, CeO{sub 2} has been shown to be effective in lowering the soot combustion temperature from 600 °C for the uncoated substrates to 370 °C for the CeO{sub 2} coated ones. It was found that the higher deposition temperatures had a positive effect on the catalyst performance.« less

  14. Particulate morphology of waste cooking oil biodiesel and diesel in a heavy duty diesel engine

    NASA Astrophysics Data System (ADS)

    Hwang, Joonsik; Jung, Yongjin; Bae, Choongsik

    2014-08-01

    The effect of biodiesel produced from waste cooking oil (WCO) on the particulate matters (PM) of a direct injection (DI) diesel engine was experimentally investigated and compared with commercial diesel fuel. Soot agglomerates were collected with a thermophoretic sampling device installed in the exhaust pipe of the engine. The morphology of soot particles was analyzed using high resolution transmission electron microscopy (TEM). The elemental and thermogravimetric analysis (TGA) were also conducted to study chemical composition of soot particles. Based on the TEM images, it was revealed that the soot derived from WCO biodiesel has a highly graphitic shell-core arrangement compared to diesel soot. The mean size was measured from averaging 400 primary particles for WCO biodiesel and diesel respectively. The values for WCO biodiesel indicated 19.9 nm which was smaller than diesel's 23.7 nm. From the TGA results, WCO biodiesel showed faster oxidation process. While the oxidation of soot particles from diesel continued until 660°C, WCO biodiesel soot oxidation terminated at 560°C. Elemental analysis results showed that the diesel soot was mainly composed of carbon and hydrogen. On the other hand, WCO biodiesel soot contained high amount of oxygen species.

  15. The Role of Phosphorus and Soot on the Deactivation of Diesel Oxidation Catalysts

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Eaton, Scott J; Nguyen, Ke; Bunting, Bruce G

    The deactivation of diesel oxidation catalysts (DOCs) by soot contamination and lube-oil derived phosphorus poisoning is investigated. Pt/CeO2/-Al2O3 DOCs aged using three different protocols developed by the authors and six high mileage field-returned DOCs of similar formulation are evaluated for THC and CO oxidation performance using a bench-flow reactor. Collectively, these catalysts exhibit a variety of phosphorus and soot morphologies contributing to performance deactivation. To isolate and examine the contribution of each deactivation mechanism, performance evaluations are carried out for each DOC ''as received'' and after removal of surface carbon in a high-temperature oxidizing environment. In such a manner themore » deactivation contribution of soot contamination is de-convoluted from that of phosphorus poisoning. It will be shown that this is accomplished while preserving phosphorus (and to a lesser degree sulfur, calcium and zinc) chemistries and concentrations within the washcoat. Washcoat contaminant information and materials changes are characterized using electron-probe microanalysis (EPMA), X-ray diffraction (XRD), scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS), BET surface area, oxygen storage capacity (OSC), X-ray fluorescence (XRF) and inductively coupled plasma (ICP) analysis, from which the relative severity of each mechanism can be quantified. Results show that soot contamination from diesel exhaust severely degrades THC and CO oxidation performance by acting as a catalyst surface diffusion barrier. This results in a considerable increase of light-off temperatures. In contrast, phosphorus poisoning, which is considered a significant deactivation mechanism in three-way catalysts, is shown to have minimal effect on DOC oxidation performance for the conditions studied here. Material changes include the formation of both Ce(III-IV) and aluminum phosphates which do not significantly hinder the THC and CO oxidation in

  16. Morphological and semi-quantitative characteristics of diesel soot agglomerates emitted from commercial vehicles and a dynamometer.

    PubMed

    Luo, Chin-Hsiang; Lee, Whei-May; Liaw, Jiun-Jian

    2009-01-01

    Diesel soot aggregates emitted from a model dynamometer and 11 on-road vehicles were segregated by a micro-orifice uniform deposit impactor (MOUDI). The elemental contents and morphological parameters of the aggregates were then examined by scanning electron microscopy coupled with an energy dispersive spectrometer (SEM-EDS), and combined with a fractional Brownian motion (fBm) processor. Two mode-size distributions of aggregates collected from diesel vehicles were confirmed. Mean mass concentration of 339 mg/m3 (dC/dlogdp) existed in the dominant mode (180-320 nm). A relatively high proportion of these aggregates appeared in PM1, accentuating the relevance regarding adverse health effects. Furthermore, the fBm processor directly parameterized the SEM images of fractal like aggregates and successfully quantified surface texture to extract Hurst coefficients (H) of the aggregates. For aggregates from vehicles equipped with a universal cylinder number, the H value was independent of engine operational conditions. A small H value existed in emitted aggregates from vehicles with a large number of cylinders. This study found that aggregate fractal dimension related to H was in the range of 1.641-1.775, which is in agreement with values reported by previous TEM-based experiments. According to EDS analysis, carbon content ranged in a high level of 30%-50% by weight for diesel soot aggregates. The presence of Na and Mg elements in these sampled aggregates indicated the likelihood that some engine enhancers composed of biofuel or surfactants were commonly used in on-road vehicles in Taiwan. In particular, the morphological H combined with carbon content detection can be useful for characterizing chain-like or cluster diesel soot aggregates in the atmosphere.

  17. Influence of fuel injection timing and pressure on in-flame soot particles in an automotive-size diesel engine.

    PubMed

    Zhang, Renlin; Kook, Sanghoon

    2014-07-15

    The current understanding of soot particle morphology in diesel engines and their dependency on the fuel injection timing and pressure is limited to those sampled from the exhaust. In this study, a thermophoretic sampling and subsequent transmission electron microscope imaging were applied to the in-flame soot particles inside the cylinder of a working diesel engine for various fuel injection timings and pressures. The results show that the number count of soot particles per image decreases by more than 80% when the injection timing is retarded from -12 to -2 crank angle degrees after the top dead center. The late injection also results in over 90% reduction of the projection area of soot particles on the TEM image and the size of soot aggregates also become smaller. The primary particle size, however, is found to be insensitive to the variations in fuel injection timing. For injection pressure variations, both the size of primary particles and soot aggregates are found to decrease with increasing injection pressure, demonstrating the benefits of high injection velocity and momentum. Detailed analysis shows that the number count of soot particles per image increases with increasing injection pressure up to 130 MPa, primarily due to the increased small particle aggregates that are less than 40 nm in the radius of gyration. The fractal dimension shows an overall decrease with the increasing injection pressure. However, there is a case that the fractal dimension shows an unexpected increase between 100 and 130 MPa injection pressure. It is because the small aggregates with more compact and agglomerated structures outnumber the large aggregates with more stretched chain-like structures.

  18. Chemical composition and heterogeneous reactivity of soot generated in the combustion of diesel and GTL (Gas-to-Liquid) fuels and amorphous carbon Printex U with NO2 and CF3COOH gases

    NASA Astrophysics Data System (ADS)

    Tapia, A.; Salgado, S.; Martín, P.; Villanueva, F.; García-Contreras, R.; Cabañas, B.

    2018-03-01

    The heterogeneous reactions of nitrogen dioxide (NO2) and trifluoroacetic acid (CF3COOH) with soot produced by diesel and GTL (gas-to-liquid) fuels were investigated using a Knudsen flow reactor with mass spectrometry as a detection system for gas phase species. Soot was generated with a 4 cylinder diesel engine working under steady-state like urban operation mode. Heterogeneous reaction of the mentioned gases with a commercial carbon, Printex U, used as reference, was also analyzed. The initial and the steady-state uptake coefficients, γ0 and γss, respectively, were measured indicating that GTL soot reacts faster than diesel soot and Printex U carbon for NO2 gas reactant. According to the number of reacted molecules on the surface, Printex U soot presents more reducing sites than diesel and GTL soot. Initial uptake coefficients for GTL and diesel soot for the reaction with CF3COOH gas reactant are very similar and no clear conclusions can be obtained related to the initial reactivity. The number of reacted molecules calculated for CF3COOH reactions shows values two orders of magnitude higher than the corresponding to NO2 reactions, indicating a greater presence of basic functionalities in the soot surfaces. More information of the surface composition has been obtained using Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) before and after the reaction of soot samples with gas reactants. As conclusion, the interface of diesel and GTL soot before reaction mainly consists of polycyclic aromatic hydrocarbons (PAHs), nitro-compounds as well as ether functionalities. After reaction with gas reactant, it was observed that PAHs and nitro-compounds remain on the soot surface and new spectral bands such as carbonyl groups (carboxylic acids, aldehydes, esters and ketones) are observed. Physical properties of soot from both fuels studied such as BET surface isotherm and SEM analysis were also developed and related to the observed reactivity.

  19. Molecular Characterization of the Gas-Particle Interface of Soot Sampled from a Diesel Engine Using a Titration Method.

    PubMed

    Tapia, A; Salgado, M S; Martín, María Pilar; Lapuerta, M; Rodríguez-Fernández, J; Rossi, M J; Cabañas, B

    2016-03-15

    Surface functional groups of two different types of combustion aerosols, a conventional diesel (EN 590) and a hydrotreated vegetable oil (HVO) soot, have been investigated using heterogeneous chemistry (i.e., gas-particle surface reactions). A commercial sample of amorphous carbon (Printex XE2-B) was analyzed as a reference substrate. A Knudsen flow reactor was used to carry out the experiments under molecular flow conditions. The selected gases for the titration experiments were: N(CH3)3 for the identification of acidic sites, NH2OH for the presence of carbonyl groups, CF3COOH and HCl for basic sites of different strength, and O3 and NO2 for reducing groups. Reactivity with N(CH3)3 indicates a lower density of acidic functionalities for Printex XE2-B in relation to diesel and HVO soot. Results for NH2OH experiments indicates that commercial amorphous carbon exhibits a lower abundance of available carbonyl groups at the interface compared to the results from diesel and HVO soot, the latter being the one with the largest abundance of carbonyl functions. Reactions with acids indicate the presence of weak basic oxides on the particle surface that preferentially interact with the strong acid CF3COOH. Finally, reactions with O3 and NO2 reveal that diesel and especially HVO have a significantly higher reactivity with both oxidizers compared to that of Printex XE2-B because they have more reducing sites by roughly a factor of 10 and 30, respectively. The kinetics of titration reactions have also been investigated.

  20. Development and characterization of a mobile photoacoustic sensor for on-line soot emission monitoring in diesel exhaust gas.

    PubMed

    Beck, H A; Niessner, R; Haisch, C

    2003-04-01

    Upcoming regulations for vehicle exhaust emission demand substantial reduction of particle emission in diesel exhaust. To achieve these emission levels, the car manufacturing industry is developing new combustion concepts and exhaust after-treatment techniques such as the use of catalysts and particle filters. Many of the state-of-the-art analytical instruments do not meet the required detection limits, in combination with a high temporal resolution necessary for engine optimization. This paper reports a new detection system and the first results of its application to on-line diesel exhaust soot measurements on a engine test bench (MAN diesel engine facility Nürnberg, Germany). The instrument is based on differential photoacoustic (PA) spectroscopy of black carbon aerosol. It contains two identical PA cells, one for the measurement of the aerosol particles and one which analyses the particle-free gas. Thus, a potential cross-sensitivity to gaseous absorbers in the exhaust gas can be excluded. The PA cells were characterized in a laboratory set-up, with water vapor as reference gas and artificial soot generated by a spark discharge generator. The detection limit was found to be 2 microg m(-3) BC (for diesel soot) with a sampling rate of 3 Hz. The temporal response of the system was found to be in the order of 1 s. After full characterization of the cells, the system was transferred into a mobile 19"-rack. Characterization of the mobile sensor system under real-world conditions was performed during several measurement campaigns at an engine test bench for heavy-duty diesel engines. Results for the limit of detection, the time resolution, accuracy, repeatability, and robustness of the sensor system are very promising with regards to a routine application of the system in engine development.

  1. The investigation of soot and temperature distributions in a visualized direct injection diesel engine using laser diagnostics

    NASA Astrophysics Data System (ADS)

    Han, Yong-taek; Kim, Ki-bum; Lee, Ki-hyung

    2008-11-01

    Based upon the method of temperature calibration using the diffusion flame, the temperature and soot concentrations of the turbulent flame in a visualized diesel engine were qualitatively measured. Two different cylinder heads were used to investigate the effect of swirl ratio within the combustion chamber. From this experiment, we find that the highest flame temperature of the non-swirl head engine is approximately 2400 K and that of the swirl head engine is 2100 K. In addition, as the pressure of fuel injection increases, the in-cylinder temperature increases due to the improved combustion of a diesel engine. This experiment represented the soot quantity in the KL factor and revealed that the KL factor was high when the fuel collided with the cylinder wall. Moreover, the KL factor was also high in the area of the chamber where the temperature dropped rapidly.

  2. Soot and liquid-phase fuel distributions in a newly designed optically accessible DI diesel engine

    NASA Astrophysics Data System (ADS)

    Dec, J. E.; Espey, C.

    1993-10-01

    Two-dimensional (2-D) laser-sheet imaging has been used to examine the soot and liquid-phase fuel distributions in a newly designed, optically accessible, direct-injection diesel engine of the heavy-duty size class. The design of this engine preserves the intake port geometry and basic dimensions of a Cummins N-series production engine. It also includes several unique features to provide considerable optical access. Liquid-phase fuel and soot distribution studies were conducted at a medium speed (1,200 rpm) using a Cummins closed-nozzle fuel injector. The scattering was used to obtain planar images of the liquid-phase fuel distribution. These images show that the leading edge of the liquid-phase portion of the fuel jet reaches a maximum length of 24 mm, which is about half the combustion bowl radius for this engine. Beyond this point virtually all the fuel has vaporized. Soot distribution measurements were made at a high load condition using three imaging diagnostics: natural flame luminosity, 2-D laser-induced incandescence, and 2-D elastic scattering. This investigation showed that the soot distribution in the combusting fuel jet develops through three stages. First, just after the onset of luminous combustion, soot particles are small and nearly uniformly distributed throughout the luminous region of the fuel jet. Second, after about 2 crank angle degrees a pattern develops of a higher soot concentration of larger sized particles in the head vortex region of the jet and a lower soot concentration of smaller sized particles upstream toward the injector. Third, after fuel injection ends, both the soot concentration and soot particle size increase rapidly in the upstream portion of the fuel jet.

  3. Investigation of a tripropylene-glycol monomethyl ether and diesel blend for soot-free combustion in an optical direct-injection diesel engine

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dumitrescu, Cosmin E.; Mueller, Charles J.; Kurtz, Eric

    Natural luminosity and chemiluminescence imaging diagnostics were employed to investigate if a 50/50 blend by volume of tripropylene-glycol monomethyl ether (TPGME) and ultra-low sulfur #2 diesel certification fuel (CF) could enable leaner-lifted flame combustion (LLFC), a non-sooting mode of mixing-controlled combustion associated with equivalence ratios below approximately 2. The experiments were performed in a singlecylinder heavy-duty optical compression-ignition engine at three injection pressures and three dilution levels. Results indicate that TPGME addition effectively eliminated engine-out smoke emissions by curtailing soot production and/or increasing soot oxidation during and after the end of fuel injection. TPGME greatly reduced soot luminosity when compared with neat CF, but did not enable LLFC because the equivalence ratios at the lift-off length,more » $$\\phi$$(H), never reached the non-sooting limit. Nevertheless, this study showed that TPGME addition has the potential to enable LLFC under different experimental conditions that would further decrease $$\\phi$$(H) to ~ 2 and below. Concerning other engine-out emissions, injection pressure influenced the effects of TPGME addition on NO x emissions. Finally, HC and CO emissions were higher compared to baseline fuel likely due to the lower net heat of combustion of TPGME and the need to limit fuel-injection duration for valid optical measurements.« less

  4. Investigation of a tripropylene-glycol monomethyl ether and diesel blend for soot-free combustion in an optical direct-injection diesel engine

    DOE PAGES

    Dumitrescu, Cosmin E.; Mueller, Charles J.; Kurtz, Eric

    2015-12-31

    Natural luminosity and chemiluminescence imaging diagnostics were employed to investigate if a 50/50 blend by volume of tripropylene-glycol monomethyl ether (TPGME) and ultra-low sulfur #2 diesel certification fuel (CF) could enable leaner-lifted flame combustion (LLFC), a non-sooting mode of mixing-controlled combustion associated with equivalence ratios below approximately 2. The experiments were performed in a singlecylinder heavy-duty optical compression-ignition engine at three injection pressures and three dilution levels. Results indicate that TPGME addition effectively eliminated engine-out smoke emissions by curtailing soot production and/or increasing soot oxidation during and after the end of fuel injection. TPGME greatly reduced soot luminosity when compared with neat CF, but did not enable LLFC because the equivalence ratios at the lift-off length,more » $$\\phi$$(H), never reached the non-sooting limit. Nevertheless, this study showed that TPGME addition has the potential to enable LLFC under different experimental conditions that would further decrease $$\\phi$$(H) to ~ 2 and below. Concerning other engine-out emissions, injection pressure influenced the effects of TPGME addition on NO x emissions. Finally, HC and CO emissions were higher compared to baseline fuel likely due to the lower net heat of combustion of TPGME and the need to limit fuel-injection duration for valid optical measurements.« less

  5. LES of Sooting Flames

    DTIC Science & Technology

    2006-12-01

    27], [28] on soot nucleation, and [29] on the soot formation in diesel engines . [27] discussed the unresolved problems in SOx, NOx , and soot...used LEM approach to study aerosol dynamics in engine exhaust plumes. Recently, [41] used detailed NOx mechanism combined with MOM to predict the...combustion engines . For instance, the laminar flamelet approach used by [43, 44, 45], allows the usage of a detailed chemical mechanism but is not

  6. Using Carbon-14 Isotope Tracing to Investigate Molecular Structure Effects of the Oxygenate Dibutyl Maleate on Soot Emissions from a DI Diesel Engine

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Buchholz, B A; Mueller, C J; Upatnieks, A

    2004-01-07

    The effect of oxygenate molecular structure on soot emissions from a DI diesel engine was examined using carbon-14 ({sup 14}C) isotope tracing. Carbon atoms in three distinct chemical structures within the diesel oxygenate dibutyl maleate (DBM) were labeled with {sup 14}C. The {sup 14}C from the labeled DBM was then detected in engine-out particulate matter (PM), in-cylinder deposits, and CO{sub 2} emissions using accelerator mass spectrometry (AMS). The results indicate that molecular structure plays an important role in determining whether a specific carbon atom either does or does not form soot. Chemical-kinetic modeling results indicate that structures that produce CO{submore » 2} directly from the fuel are less effective at reducing soot than structures that produce CO before producing CO{sub 2}. Because they can follow individual carbon atoms through a real combustion process, {sup 14}C isotope tracing studies help strengthen the connection between actual engine emissions and chemical-kinetic models of combustion and soot formation/oxidation processes.« less

  7. Progression of soot cake layer properties during the systematic regeneration of diesel particulate filters measured with neutron tomography

    DOE PAGES

    Toops, Todd J.; Pihl, Josh A.; Finney, Charles E. A.; ...

    2015-01-16

    Although particulate filters (PFs) have been a key component of the emission control system for modern diesel engines, there remain significant questions about the basic regeneration behavior of the filters and how it changes with accumulation of increasing soot layers. This effort describes a systematic deposition and regeneration of particulate matter in 25-mm diameter × 76-mm long wall-flow PFs composed of silicon carbide (SiC) material. The initial soot distributions were analyzed for soot cake thickness using a nondestructive neutron imaging technique. With the PFs intact, it was then possible to sequentially regenerate the samples and reanalyze them, which was performedmore » after nominal 20, 50, and 70 % regenerations. The loaded samples show a relatively uniform distribution of particulate with an increasing soot cake thickness and nearly identical initial density of 70 mg/cm 3. Throughout regeneration, the soot cake thickness initially decreases significantly while the density increases to 80–90 mg/cm 3. After ~50 % regeneration, the soot cake thickness stays relatively constant, but instead, the density decreases as pores open up in the layer (~35 mg/cm 3 at 70 % regeneration). Here, complete regeneration initially occurs at the rear of the PF channels. With this information, a conceptual model of the regeneration is proposed.« less

  8. Progression of soot cake layer properties during the systematic regeneration of diesel particulate filters measured with neutron tomography

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Toops, Todd J.; Pihl, Josh A.; Finney, Charles E. A.

    Although particulate filters (PFs) have been a key component of the emission control system for modern diesel engines, there remain significant questions about the basic regeneration behavior of the filters and how it changes with accumulation of increasing soot layers. This effort describes a systematic deposition and regeneration of particulate matter in 25-mm diameter × 76-mm long wall-flow PFs composed of silicon carbide (SiC) material. The initial soot distributions were analyzed for soot cake thickness using a nondestructive neutron imaging technique. With the PFs intact, it was then possible to sequentially regenerate the samples and reanalyze them, which was performedmore » after nominal 20, 50, and 70 % regenerations. The loaded samples show a relatively uniform distribution of particulate with an increasing soot cake thickness and nearly identical initial density of 70 mg/cm 3. Throughout regeneration, the soot cake thickness initially decreases significantly while the density increases to 80–90 mg/cm 3. After ~50 % regeneration, the soot cake thickness stays relatively constant, but instead, the density decreases as pores open up in the layer (~35 mg/cm 3 at 70 % regeneration). Here, complete regeneration initially occurs at the rear of the PF channels. With this information, a conceptual model of the regeneration is proposed.« less

  9. The rapid alveolar absorption of diesel soot-adsorbed benzo[a]pyrene: bioavailability, metabolism and dosimetry of an inhaled particle-borne carcinogen.

    PubMed

    Gerde, P; Muggenburg, B A; Lundborg, M; Dahl, A R

    2001-05-01

    Exposure to diesel exhaust may contribute to lung cancer in humans. It remains unclear whether the carbonaceous core of the soot particle or its coat of adsorbed/condensed organics contributes most to cancer risk. Equally unclear are the extent and rate at which organic procarcinogens desorb from soot particles in the lungs following inhalation exposure and the extent of their metabolic activation in the lungs. To explore the basic relationship between a model polycyclic aromatic hydrocarbon (PAH) and a typical carrier particle, we investigated the rate and extent of release and metabolic fate of benzo[a]pyrene (BaP) adsorbed on the carbonaceous core of diesel soot. The native organic content of the soot had been denuded by toluene extraction. Exogenous BaP was adsorbed onto the denuded soot as a surface coating corresponding to 25% of a monomolecular layer. Dogs were exposed by inhalation to an aerosol bolus of the soot-adsorbed BAP: Following deposition in the alveolar region a fraction of BaP was rapidly desorbed from the soot and quickly absorbed into the circulation. Release rates then decreased drastically. When coatings reached approximately 16% of a monolayer the remaining BaP was not bioavailable and was retained on the particles after 5.6 months in the lung. However, the bioavailability of particles transported to the lymph nodes was markedly higher; after 5.6 months the surface coating of BaP was reduced to 10%. BaP that remained adsorbed on the soot surface after this period was approximately 30% parent compound. In contrast, the rapidly released pulse of BaP, which was quickly absorbed through the alveolar epithelium after inhalation, appeared mostly unmetabolized in the circulation, along with low concentrations of phase I and phase II BaP metabolites. However, within approximately 1 h this rapidly absorbed fraction of BaP was systemically metabolized into mostly conjugated phase II metabolites. The results indicate that absorption through the

  10. [Catalytic combustion of soot on combined oxide catalysts].

    PubMed

    He, Xu-wen; Yu, Jun-jie; Kang, Shou-fang; Hao, Zheng-ping; Hu, Chun

    2005-01-01

    Combined oxide catalysts are prepared for catalytic combustion of soot and regeneration from diesel emissions. Thermo-gravimetric analysis(TGA) and temperature programmed oxidation(TPO)are used to evaluate the activity of catalysts under the influence of composition,atomic ration, H2O, calcinations temperature and mass ration between catalysts and soot. Results show that Cu-Mo-O had high activity among double metal oxide catalysts. Among multicomponent metal oxide catalysts, Cu-K-Mo-O had high activity when atomic ratio Cu: K: Mo = 1:1:2 and mass ration between catalysts and soot equals 5: 1. Under this condition, soot ignition temperature of Cu-K-Mo-O catalyst was 327 degrees C. H2O addition and calcinations temperature had little influence on it,which is one kind of compatible catalyst for soot control and catalytic regeneration from diesel emissions.

  11. Conductometric Sensor for Soot Mass Flow Detection in Exhausts of Internal Combustion Engines

    PubMed Central

    Feulner, Markus; Hagen, Gunter; Müller, Andreas; Schott, Andreas; Zöllner, Christian; Brüggemann, Dieter; Moos, Ralf

    2015-01-01

    Soot sensors are required for on-board diagnostics (OBD) of automotive diesel particulate filters (DPF) to detect filter failures. Widely used for this purpose are conductometric sensors, measuring an electrical current or resistance between two electrodes. Soot particles deposit on the electrodes, which leads to an increase in current or decrease in resistance. If installed upstream of a DPF, the “engine-out” soot emissions can also be determined directly by soot sensors. Sensors were characterized in diesel engine real exhausts under varying operation conditions and with two different kinds of diesel fuel. The sensor signal was correlated to the actual soot mass and particle number, measured with an SMPS. Sensor data and soot analytics (SMPS) agreed very well, an impressing linear correlation in a double logarithmic representation was found. This behavior was even independent of the used engine settings or of the biodiesel content. PMID:26580621

  12. Conductometric Sensor for Soot Mass Flow Detection in Exhausts of Internal Combustion Engines.

    PubMed

    Feulner, Markus; Hagen, Gunter; Müller, Andreas; Schott, Andreas; Zöllner, Christian; Brüggemann, Dieter; Moos, Ralf

    2015-11-13

    Soot sensors are required for on-board diagnostics (OBD) of automotive diesel particulate filters (DPF) to detect filter failures. Widely used for this purpose are conductometric sensors, measuring an electrical current or resistance between two electrodes. Soot particles deposit on the electrodes, which leads to an increase in current or decrease in resistance. If installed upstream of a DPF, the "engine-out" soot emissions can also be determined directly by soot sensors. Sensors were characterized in diesel engine real exhausts under varying operation conditions and with two different kinds of diesel fuel. The sensor signal was correlated to the actual soot mass and particle number, measured with an SMPS. Sensor data and soot analytics (SMPS) agreed very well, an impressing linear correlation in a double logarithmic representation was found. This behavior was even independent of the used engine settings or of the biodiesel content.

  13. Experimental correlations for transient soot measurement in diesel exhaust aerosol with light extinction, electrical mobility and diffusion charger sensor techniques

    NASA Astrophysics Data System (ADS)

    Bermúdez, Vicente; Pastor, José V.; López, J. Javier; Campos, Daniel

    2014-06-01

    A study of soot measurement deviation using a diffusion charger sensor with three dilution ratios was conducted in order to obtain an optimum setting that can be used to obtain accurate measurements in terms of soot mass emitted by a light-duty diesel engine under transient operating conditions. The paper includes three experimental phases: an experimental validation of the measurement settings in steady-state operating conditions; evaluation of the proposed setting under the New European Driving Cycle; and a study of correlations for different measurement techniques. These correlations provide a reliable tool for estimating soot emission from light extinction measurement or from accumulation particle mode concentration. There are several methods and correlations to estimate soot concentration in the literature but most of them were assessed for steady-state operating points. In this case, the correlations are obtained by more than 4000 points measured in transient conditions. The results of the new two correlations, with less than 4% deviation from the reference measurement, are presented in this paper.

  14. Airborne concentrations of benzene due to diesel locomotive exhaust in a roundhouse.

    PubMed

    Madl, Amy K; Paustenbach, Dennis J

    2002-12-13

    Concentrations of airborne benzene due to diesel exhaust from a locomotive were measured during a worst-case exposure scenario in a roundhouse. To understand the upper bound human health risk due to benzene, an electromotive diesel and a General Electric four-cycle turbo locomotive were allowed to run for four 30-min intervals during an 8-h workshift in a roundhouse. Full-shift and 1-h airborne concentrations of benzene were measured in the breathing zone of surrogate locomotive repairmen over the 8-h workshift on 2 consecutive days. In addition, carbon monoxide was measured continuously; elemental carbon (surrogate for diesel exhaust) was sampled with full-shift area samples; and nitrogen dioxide/nitric oxide was sampled using full-shift and 15-min (nitrogen dioxide only) area samples. Peak concentrations of carbon monoxide ranged from 22.5 to 93 ppm. The average concentration of elemental carbon for each day of the roundhouse study was 0.0543 and 0.0552 microg/m(3 )for an 8-h workshift. These were considered "worst-case" conditions since the work environment was intolerably irritating to the eyes, nose, and throat. Short-term nitrogen dioxide concentrations ranged from 0.81 to 2.63 ppm during the diesel emission events with the doors closed. One-hour airborne benzene concentrations ranged from 0.001 to 0.015 ppm with 45% of the measurements below the detection limit of 0.002-0.004 ppm. Results indicated that the 8-h time-weighted average for benzene in the roundhouse was approximately 100-fold less than the current threshold limit value (TLV) of 0.5 ppm. These data are consistent with other studies, which have indicated that benzene concentrations due to diesel emissions, even in a confined environment, are quite low.

  15. Development and Characterization of Laser-Induced Incandescence Towards Nanoparticle (Soot) Detection

    NASA Technical Reports Server (NTRS)

    VanderWal, Randy L.

    2000-01-01

    The production of particulates, notably soot, during combustion has both positive and negative ramifications. Exhaust from diesel engines under load (for example, shifting gears), flickering candle flames and fireplaces all produce soot leaving a flame. From an efficiency standpoint, emission of soot from engines, furnaces or even a simple flickering candle flame represents a loss of useful energy. The emission of soot from diesel engines, furnaces, power generation facilities, incinerators and even simple flames poses a serious environmental problem and health risk. Yet some industries intentionally produce soot as carbon black for use in inks, copier toner, tires and as pigments. Similarly, the presence of soot within flames can act both positively and negatively. Energy transfer from a combustion process is greatly facilitated by the radiative heat transfer from soot yet radiative heat transfer also facilitates the spread of unwanted fires. To understand soot formation and develop control strategies for soot emission/formation, measurements of soot concentration in both practical devices such as engines and controlled laboratory flames are necessary. Laser-induced incandescence (LII) has been developed and characterized to address this need, as described here.

  16. Laminar Soot Processes Experiment Shedding Light on Flame Radiation

    NASA Technical Reports Server (NTRS)

    Urban, David L.

    1998-01-01

    The Laminar Soot Processes (LSP) experiment investigated soot processes in nonturbulent, round gas jet diffusion flames in still air. The soot processes within these flames are relevant to practical combustion in aircraft propulsion systems, diesel engines, and furnaces. However, for the LSP experiment, the flames were slowed and spread out to allow measurements that are not tractable for practical, Earth-bound flames.

  17. Source identification of individual soot agglomerates in Arctic air by transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    Weinbruch, S.; Benker, N.; Kandler, K.; Schütze, K.; Kling, K.; Berlinger, B.; Thomassen, Y.; Drotikova, T.; Kallenborn, R.

    2018-01-01

    Individual soot agglomerates collected at four different locations on the Arctic archipelago Svalbard (Norway) were characterised by transmission electron microscopy and energy-dispersive X-ray microanalysis. For source identification of the ambient soot agglomerates, samples from different local sources (coal burning power plants in Longyearbyen and Barentsburg, diesel and oil burning for power generation in Sveagruva and Ny Ålesund, cruise ship) as well as from other sources which may contribute to Arctic soot concentrations (biomass burning, aircraft emissions, diesel engines) were investigated. Diameter and graphene sheet separation distance of soot primary particles were found to be highly variable within each source and are not suited for source identification. In contrast, concentrations of the minor elements Si, P, K, Ca and Fe showed significant differences which can be used for source attribution. The presence/absence of externally mixed particle groups (fly ashes, tar balls, mercury particles) gives additional hints about the soot sources. Biomass/wood burning, ship emissions and coal burning in Barentsburg can be excluded as major source for ambient soot at Svalbard. The coal power plant in Longyearbyen is most likely a major source of soot in the settlement of Longyearbyen but does not contribute significantly to soot collected at the Global Atmosphere Watch station Zeppelin Mountain near Ny Ålesund. The most probable soot sources at Svalbard are aircraft emissions and diesel exhaust as well as long range transport of coal burning emissions.

  18. Effect of relative humidity on soot - secondary organic aerosol mixing: A case study from the Soot Aerosol Aging Study (PNNL-SAAS)

    NASA Astrophysics Data System (ADS)

    Sharma, N.; China, S.; Zaveri, R. A.; Shilling, J. E.; Pekour, M. S.; Liu, S.; Aiken, A. C.; Dubey, M. K.; Wilson, J. M.; Zelenyuk, A.; OBrien, R. E.; Moffet, R.; Gilles, M. K.; Gourihar, K.; Chand, D.; Sedlacek, A. J., III; Subramanian, R.; Onasch, T. B.; Laskin, A.; Mazzoleni, C.

    2014-12-01

    Atmospheric processing of fresh soot particles emitted by anthropogenic as well as natural sources alters their physical and chemical properties. For example, fresh and aged soot particles interact differently with incident solar radiation, resulting in different overall radiation budgets. Varying atmospheric chemical and meteorological conditions can result in complex soot mixing states. The Soot Aerosol Aging Study (SAAS) was conducted at the Pacific Northwest National Laboratory in November 2013 and January 2014 as a step towards understanding the evolution of mixing state of soot and its impact on climate-relevant properties. Aging experiments on diesel soot were carried out in a controlled laboratory chamber, and the effects of condensation and coagulation processes were systematically explored in separate sets of experiments. In addition to online measurement of aerosol properties, aerosol samples were collected for offline single particle analysis to investigate the evolution of the morphology, elemental composition and fine structure of sample particles from different experiments. Condensation experiments focused on the formation of α-pinene secondary organic aerosol on diesel soot aerosol seeds. Experiments were conducted to study the aging of soot under dry (RH < 2%) and humid conditions (RH ~ 80%). We present an analysis of the morphology of soot, its evolution, and its correlation with optical properties, as the condensation of α-pinene SOA is carried out for the two different RH conditions. The analysis was performed by using scanning electron microscopy, transmission electron microscopy, scanning transmission x-ray microscopy and atomic force microscopy for single particle characterization. In addition, particle size, mass, composition, shape, and density were characterized in-situ, as a function of organics condensed on soot seeds, using single particle mass spectrometer.

  19. Role of engine age and lubricant chemistry on the characteristics of EGR soot

    NASA Astrophysics Data System (ADS)

    Adeniran, Olusanmi Adeniji

    Exhaust products of Diesel Engines serves as an environmental hazard, and to curtail this problem a Tier 3 emission standard was introduced which involves change in engine designs and introduction of EGR systems in Diesel engines. EGR systems, however has the challenge of generating soot which are abrasive and are major causes of wear in Diesel engines. This work has studied the characteristics of EGR soot formed in different range of engine age and in different lubricant chemistries of Mineral and Synthetic based diesel Oils. It is found that lubricant degradation is encouraged by less efficient combustion as engine age increases, and these are precursors to formation of crystalline and amorphous particles that are causes of wear in Diesel Engines. It is found that soot from new engine is dominated by calcium based crystals which are from calcium sulfonate detergent, which reduces formation of second phase particles that can be abrasive. Diversity and peak intensity is seen to increase in soot samples as engine age increases. This understanding of second phase particles formed in engines across age ranges can help in the durability development of engine, improvement of Oil formulation for EGR engines, and in development of chemistries for after-treatment Oil solutions that can combat formation of abrasive particles in Oils.

  20. Effect of diesel oxidation catalysts on the diesel particulate filter regeneration process.

    PubMed

    Lizarraga, Leonardo; Souentie, Stamatios; Boreave, Antoinette; George, Christian; D'Anna, Barbara; Vernoux, Philippe

    2011-12-15

    A Diesel Particulate Filter (DPF) regeneration process was investigated during aftertreatment exhaust of a simulated diesel engine under the influence of a Diesel Oxidation Catalyst (DOC). Aerosol mass spectrometry analysis showed that the presence of the DOC decreases the Organic Carbon (OC) fraction adsorbed to soot particles. The activation energy values determined for soot nanoparticles oxidation were 97 ± 5 and 101 ± 8 kJ mol(-1) with and without the DOC, respectively; suggesting that the DOC does not facilitate elementary carbon oxidation. The minimum temperature necessary for DPF regeneration was strongly affected by the presence of the DOC in the aftertreatment. The conversion of NO to NO(2) inside the DOC induced the DPF regeneration process at a lower temperature than O(2) (ΔT = 30 K). Also, it was verified that the OC fraction, which decreases in the presence of the DOC, plays an important role to ignite soot combustion.

  1. Control of diesel soot and NOx emissions with a particulate trap and EGR.

    PubMed

    Liu, Rui-xiang; Gao, Xi-yan; Yang, De-sheng; Xu, Xiao-guang

    2005-01-01

    The exhaust gas recirculation (EGR), coupled with a high-collection efficiency particulate trap to simultaneously control smoke and NOx emissions from diesel engines were studied. This ceramic trap developed previously provided the soot cleaning efficiency of 99%, the regeneration efficiency reaches 80% and the ratio of success reaches 97%, which make EGR used in diesel possible. At the presence of EGR, opening of the regeneration control valve of the trap was over again optimized to compensate for the decrease of the oxygen concentration in the exhaust gas resulted from EGR. The results indicated the cleaning efficiency and regeneration performance of the trap were maintained at the same level except that the back pressure increased faster. A new EGR system was developed, which is based on a wide range oxygen (UEGO) sensor. Experiments were carried out under steady state conditions while maintaining the engine speed at 1600 r/min, setting the engine loads at 0%, 25%, 50%, 75% and 100% respectively. Throughout each test the EGR rate was kept at nine different settings and data were taken with the gas analyzer and UEGO sensor. Then, the EGR rate and engine load maps, which showed the tendencies of NOx, CO and HC emissions from diesel engine, were made using the measured data. Using the maps, the author set up the EGR regulation, the relationship between the optimal amounts of EGR flow and the equivalence ratio, sigma, where sigma = 14.5/AFR.

  2. Soot Imaging and Measurement

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Soot, sometimes referred to as smoke, is made up primarily of the carbon particles generated by most combustion processes. For example, large quantities of soot can be seen issuing from the exhaust pipes of diesel-powered vehicles. Heated soot also is responsible for the warm orange color of candle flames, though that soot is generally consumed before it can exit the flame. Research has suggested that heavy atmospheric soot concentrations aggravate conditions such as pneumonia and asthma, causing many deaths each year. To understand the formation and oxidation of soot, NASA Lewis Research Center scientists, together with several university investigators, are investigating the properties of soot generated in reduced gravity, where the absence of buoyancy allows more time for the particles to grow. The increased time allows researchers to better study the life cycle of these particles, with the hope that increased understanding will lead to better control strategies. To quantify the amount of soot present in a flame, Lewis scientists developed a unique imaging technique that provides quantitative and qualitative soot data over a large field of view. There is significant improvement over the single-point methods normally used. The technique is shown in the sketch, where light from a laser is expanded with a microscope objective, rendered parallel, and passed through a flame where soot particles reduce the amount of light transmitted to the camera. A filter only allows light at the wavelength of the laser to pass to the camera, preventing any extraneous signals. When images of the laser light with and without the flame are compared, a quantitative map of the soot concentration is produced. In addition to that data, a qualitative image of the soot in the flame is also generated, an example of which is displayed in the photo. This technique has the potential to be adapted to real-time process control in industrial powerplants.

  3. Electron spin resonance of particulate soot samples from automobiles to help environmental studies.

    PubMed

    Yamanaka, C; Matsuda, T; Ikeya, M

    2005-02-01

    The application of electron spin resonance (ESR) was studied for diesel soot samples and suspended particulate matter (SPM) from automobile engines. Soot samples or diesel exhaust particles (DEP) were recovered at various points: in the exhaust pipe of a diesel engine, at the dust sampler of a highway tunnel (standard DEP), on the soundproofing wall alongside a heavy traffic road, and on the filters of a dust sampler for SPM. The diesel soot samples apparently showed two ESR spectra: one was a broad spectrum at g=2.1 with a line width of ca. 80-120 mT and the other was a sharp signal of a carbon radical at g=2.003 with a line width of 0.4 mT. Annealing experiments with a DEP sample at 250 degrees C revealed drastic enhancement of the sharp ESR signal, which suggested a thermal process of carbonization of remnant organics. An oximetric study by ESR showed an enhancement of the broad signal in the diesel soot sample as well as in the sharp ESR signal. Therefore, the main part of the broad ESR signal would be attributed to carbon radicals, which form a different configuration, probably closely interacting aggregates. Enhancement of the sharp ESR signal was not observed in the standard DEP sample under vacuum condition, which suggested less adsorption sites on the surface of DEP samples.

  4. Conductometric Soot Sensor for Automotive Exhausts: Initial Studies

    PubMed Central

    Hagen, Gunter; Feistkorn, Constanze; Wiegärtner, Sven; Heinrich, Andreas; Brüggemann, Dieter; Moos, Ralf

    2010-01-01

    In order to reduce the tailpipe particulate matter emissions of Diesel engines, Diesel particulate filters (DPFs) are commonly used. Initial studies using a conductometric soot sensor to monitor their filtering efficiency, i.e., to detect a malfunction of the DPF, are presented. The sensors consist of a planar substrate equipped with electrodes on one side and with a heater on the other. It is shown that at constant speed-load points, the time until soot percolation occurs or the resistance itself are reproducible means that can be well correlated with the filtering efficiency of a DPF. It is suggested to use such a sensor setup for the detection of a DPF malfunction. PMID:22294888

  5. Conductometric soot sensor for automotive exhausts: initial studies.

    PubMed

    Hagen, Gunter; Feistkorn, Constanze; Wiegärtner, Sven; Heinrich, Andreas; Brüggemann, Dieter; Moos, Ralf

    2010-01-01

    In order to reduce the tailpipe particulate matter emissions of Diesel engines, Diesel particulate filters (DPFs) are commonly used. Initial studies using a conductometric soot sensor to monitor their filtering efficiency, i.e., to detect a malfunction of the DPF, are presented. The sensors consist of a planar substrate equipped with electrodes on one side and with a heater on the other. It is shown that at constant speed-load points, the time until soot percolation occurs or the resistance itself are reproducible means that can be well correlated with the filtering efficiency of a DPF. It is suggested to use such a sensor setup for the detection of a DPF malfunction.

  6. Morphological characterization of diesel soot agglomerates based on the Beer-Lambert law

    NASA Astrophysics Data System (ADS)

    Lapuerta, Magín; Martos, Francisco J.; José Expósito, Juan

    2013-03-01

    A new method is proposed for the determination of the number of primary particles composing soot agglomerates emitted from diesel engines as well as their individual fractal dimension. The method is based on the Beer-Lambert law and it is applied to micro-photographs taken in high resolution transmission electron microscopy. Differences in the grey levels of the images lead to a more accurate estimation of the geometry of the agglomerate (in this case radius of gyration) than other methods based exclusively on the planar projections of the agglomerates. The method was validated by applying it to different images of the same agglomerate observed from different angles of incidence, and proving that the effect of the angle of incidence is minor, contrary to other methods. Finally, the comparisons with other methods showed that the size, number of primary particles and fractal dimension (the latter depending on the particle size) are usually underestimated when only planar projections of the agglomerates are considered.

  7. PORE STRUCTURE OF SOOT DEPOSITS FROM SEVERAL COMBUSTION SOURCES. (R825303)

    EPA Science Inventory

    Abstract

    Soot was harvested from five combustion sources: a dodecane flame, marine and bus diesel engines, a wood stove, and an oil furnace. The soots ranged from 20% to 90% carbon by weight and molar C/H ratios from 1 to 7, the latter suggesting a highly condensed aro...

  8. Assessing the effects of UVA photocatalysis on soot-coated TiO2-containing mortars.

    PubMed

    De la Rosa, José M; Miller, Ana Z; Pozo-Antonio, J Santiago; González-Pérez, José A; Jiménez-Morillo, Nicasio T; Dionisio, Amelia

    2017-12-15

    The deposition of soot on building surfaces darkens their colour and leads to undesirable black crusts, which are one of the most serious problems on the conservation of built cultural heritage. As a preventive strategy, self-cleaning systems based on the use of titanium dioxide (TiO 2 ) coatings have been employed on building materials for degrading organic compounds deposited on building surfaces, improving their durability and performance. In this study, the self-cleaning effect of TiO 2 -containing mortars coated with diesel soot has been appraised under laboratory conditions. The mortar samples were manufactured using lime putty and two different doses of TiO 2 (2.5% and 5%). The lime mortars were then coated with diesel engine soot and irradiated with ultraviolet A (UVA) illumination for 30days. The photocatalytic efficiency was evaluated by visual inspection, field emission scanning electron microscopy (FESEM) and colour spectrophotometry. Changes in the chemical composition of the soot particles (including persistent organic pollutants) were assessed by analytical pyrolysis (Py-GC/MS) and solid state 13 C NMR spectroscopy. The FESEM and colour spectrophotometry revealed that the soot-coated TiO 2 -containing mortars promoted a self-cleaning effect after UVA irradiation. The combination of analytical pyrolysis and 13 C solid state NMR showed that the UVA irradiation caused the cracking of polycyclic aromatic structures and n-alkyl compounds of the diesel soot and its transformation into methyl polymers. Our findings also revealed that the inclusion of TiO 2 in the lime mortar formulations catalysed these transformations promoting the self-cleaning of the soot-stained mortars. The combined action of TiO 2 and UVA irradiation is a promising proxy to clean lime mortars affected by soot deposition. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Fullerene Soot in Eastern China Air: Results from Soot Particle-Aerosol Mass Spectrometer

    NASA Astrophysics Data System (ADS)

    Wang, J.; Ge, X.; Chen, M.; Zhang, Q.; Yu, H.; Sun, Y.; Worsnop, D. R.; Collier, S.

    2015-12-01

    In this work, we present for the first time, the observation and quantification of fullerenes in ambient airborne particulate using an Aerodyne Soot Particle - Aerosol Mass Spectrometer (SP-AMS) deployed during 2015 winter in suburban Nanjing, a megacity in eastern China. The laser desorption and electron impact ionization techniques employed by the SP-AMS allow us to differentiate various fullerenes from other aerosol components. Mass spectrum of the identified fullerene soot is consisted by a series of high molecular weight carbon clusters (up to m/z of 2000 in this study), almost identical to the spectral features of commercially available fullerene soot, both with C70 and C60 clusters as the first and second most abundant species. This type of soot was observed throughout the entire study period, with an average mass loading of 0.18 μg/m3, accounting for 6.4% of the black carbon mass, 1.2% of the total organic mass. Temporal variation and diurnal pattern of fullerene soot are overall similar to those of black carbon, but are clearly different in some periods. Combining the positive matrix factorization, back-trajectory and analyses of the meteorological parameters, we identified the petrochemical industrial plants situating upwind from the sampling site, as the major source of fullerene soot. In this regard, our findings imply the ubiquitous presence of fullerene soot in ambient air of industry-influenced area, especially the oil and gas production regions. This study also offers new insights into the characterization of fullerenes from other environmental samples via the advanced SP-AMS technique.

  10. A morphological investigation of soot produced by the detonation of munitions.

    PubMed

    Pantea, Dana; Brochu, Sylvie; Thiboutot, Sonia; Ampleman, Guy; Scholz, Günter

    2006-10-01

    The morphology of three different detonation soot samples along with other common soot materials such as carbon black, diesel soot and chimney soot was studied by elemental and proximate analysis, X-ray diffraction and electron microscopy. The goal of this study was to better define the morphology of the detonation soot in order to better assess the interactions of this type of soot with explosive residues. The detonation soot samples were obtained by the detonation of artillery 155mm projectiles filled with either pure TNT (2,4,6-trinitrotoluene) or composition B, a military explosive based on a mixture of TNT and RDX (trimethylentrinitramine). The carbon content of the soot samples varied considerably depending on the feedstock composition. Detonation soot contains less carbon and more nitrogen than the other carbonaceous samples studied, due to the molecular structure of the energetic materials detonated such as TNT and RDX. The ash concentration was higher for detonation soot samples due to the high metal content coming from the projectiles shell and to the soil contamination which occurred during the detonation. By X-ray diffraction, diamond and graphite were found to be the major crystalline carbon forms in the detonation soot. Two electron microscopy techniques were used in this study to visualise the primary particles and to try to explain the formation mechanism of detonation soot samples.

  11. Review of Diesel Combustion Models for NOx and Smoke Emissions

    DOT National Transportation Integrated Search

    1977-10-01

    A comprehensive review of diesel emissions models is presented together with assessments of the pertinent fundamental NOx and soot kinetics. The results of diesel emissions experiments carried out at Southampton are also presented and correlations ar...

  12. Laser-induced incandescence measurements in a fired diesel engine at 3 kHz

    NASA Astrophysics Data System (ADS)

    Boxx, I. G.; Heinold, O.; Geigle, K. P.

    2015-01-01

    Laser-induced incandescence (LII) was performed at 3 kHz in an optically accessible cylinder of a fired diesel engine using a commercially available diode-pumped solid-state laser and an intensified CMOS camera. The resulting images, acquired every 3° of crank angle, enabled the spatiotemporal tracking of soot structures during the expansion/exhaust stroke of the engine cycle. The image sequences demonstrate that soot tends to form in thin sheets that propagate and interact with the in-cylinder flow. These sheets tend to align parallel to the central axis of the cylinder and are frequently wrapped into conical spirals by aerodynamic swirl. Most of the soot is observed well away from the cylinder walls. Quantitative soot measurements were beyond the scope of this study but the results demonstrate the practical utility of using kHz-rate LII to acquire ensemble-averaged statistical data with high crank angle resolution over a complete engine cycle. Based on semi-quantitative measures of soot distribution, it was possible to identify soot dynamics related to incomplete charge exchange. This study shows that long-duration, multi-kHz acquisition rate LII measurements are viable in a fired diesel engine with currently available laser and camera technology, albeit only in the expansion and exhaust phase of the cycle at present. Furthermore, such measurements yield useful insight into soot dynamics and therefore constitute an important new tool for the development and optimization of diesel engine technology.

  13. SENSOR FOR MONITORING OF PARTICULATE EMISSIONS IN DIESEL EXHAUST GASES - PHASE I

    EPA Science Inventory

    Active Spectrum, Inc., proposes a novel, low-cost soot sensor for on-board measurement of soot emissions in diesel exhaust gases. The proposed technology is differentiated from existing methods by excellent sensitivity, high specificity to carbon particulates, and robustness ...

  14. Pb, Sr and Nd isotopic composition and trace element characteristics of coarse airborne particles collected with passive samplers

    NASA Astrophysics Data System (ADS)

    Hoàng-Hòa, Thi Bich; Stille, Peter; Dietze, Volker; Guéguen, Florence; Perrone, Thierry; Gieré, Reto

    2015-09-01

    Passive samplers for collection of coarse airborne particulate matter have been installed in and around the coal-mining town of Cam Pha, Quang Ninh Province (Vietnam). Analysis of Pb, Sr, and Nd isotope ratios and of major and trace element distribution patterns in atmospheric particulates collected at three stations allowed for the identification of four important dust components: (1) coal dust from an open-pit mine and fly ash particles from a coal-fired power station, (2) diesel soot, (3) traffic dust from metal, tire and pavement abrasion, and (4) limestone-derived dust. Outside of the coal-mining area, traffic-derived dust defines the atmospheric baseline composition of the studied environment.

  15. Physico-Chemical Characterization of Fine and Ultrafine Particles Emitted during Diesel Particulate Filter Active Regeneration of Euro5 Diesel Vehicles.

    PubMed

    R'Mili, Badr; Boréave, Antoinette; Meme, Aurelie; Vernoux, Philippe; Leblanc, Mickael; Noël, Ludovic; Raux, Stephane; D'Anna, Barbara

    2018-03-06

    Diesel particulate filters (DPFs) are commonly employed in modern passenger cars to comply with current particulate matter (PM) emission standards. DPFs requires periodic regeneration to remove the accumulated matter. During the process, high-concentration particles, in both nucleation and accumulation modes, are emitted. Here, we report new information on particle morphology and chemical composition of fine (FPs) and ultrafine particles (UFPs) measured downstream of the DPF during active regeneration of two Euro 5 passenger cars. The first vehicle was equipped with a close-coupled diesel oxidation catalyst (DOC) and noncatalyzed DPF combined with fuel borne catalyst and the second one with DOC and a catalyzed-diesel particle filter (CDPF). Differences in PM emission profiles of the two vehicles were related to different after treatment design, regeneration strategies, and vehicle characteristics and mileage. Particles in the nucleation mode consisted of ammonium bisulfate, sulfate and sulfuric acid, suggesting that the catalyst desulfation is the key process in the formation of UFPs. Larger particles and agglomerates, ranging from 90 to 600 nm, consisted of carbonaceous material (soot and soot aggregates) coated by condensable material including organics, ammonium bisulfate and sulfuric acid. Particle emission in the accumulation mode was due to the reduced filtration efficiency (soot cake oxidation) throughout the regeneration process.

  16. [Preparation of ethanol-diesel fuel blends and exhausts emission characteristics in diesel engine].

    PubMed

    Zhang, Runduo; He, Hong; Zhang, Changbin; Shi, Xiaoyan

    2003-07-01

    The technology that diesel oil is partly substituted by ethanol can reduce diesel engine exhausts emission, especially fuel soot. This research is concentrated on preparation of ethanol-diesel blend fuel and exhausts emission characteristics using diesel engine bench. Absolute ethanol can dissolve into diesel fuel at an arbitrary ratio. However, a trace of water (0.2%) addition can lead to the phase separation of blends. Organic additive synthesized during this research can develop the ability of resistance to water and maintain the stability of ethanol-diesel-trace amounts of water system. The effects of 10%, 20%, and 30% ethanol-diesel fuel blends on exhausts emission, were compared with that of diesel fuel in direct injection (DI) diesel engine. The optimum ethanol percentage for ethanol-diesel fuel blends was 20%. Using 20% ethanol-diesel fuel blend with 2% additive of the total volume, bench diesel engine showed a large amount decrease of exhaust gas, e.g. 55% of Bosch smoke number, 70% of HC emission, and 45% of CO emission at 13 kW and 1540 r/min. Without the addition of additive, the blend of ethanol produced new organic compounds such as ethanol and acetaldehyde in tail gas. However, the addition of additive obviously reduced the emission of ethanol and acetaldehyde.

  17. Characterisation of nano- and micron-sized airborne and collected subway particles, a multi-analytical approach.

    PubMed

    Midander, Klara; Elihn, Karine; Wallén, Anna; Belova, Lyuba; Karlsson, Anna-Karin Borg; Wallinder, Inger Odnevall

    2012-06-15

    Continuous daily measurements of airborne particles were conducted during specific periods at an underground platform within the subway system of the city center of Stockholm, Sweden. Main emphasis was placed on number concentration, particle size distribution, soot content (analyzed as elemental and black carbon) and surface area concentration. Conventional measurements of mass concentrations were conducted in parallel as well as analysis of particle morphology, bulk- and surface composition. In addition, the presence of volatile and semi volatile organic compounds within freshly collected particle fractions of PM(10) and PM(2.5) were investigated and grouped according to functional groups. Similar periodic measurements were conducted at street level for comparison. The investigation clearly demonstrates a large dominance in number concentration of airborne nano-sized particles compared to coarse particles in the subway. Out of a mean particle number concentration of 12000 particles/cm(3) (7500 to 20000 particles/cm(3)), only 190 particles/cm(3) were larger than 250 nm. Soot particles from diesel exhaust, and metal-containing particles, primarily iron, were observed in the subway aerosol. Unique measurements on freshly collected subway particle size fractions of PM(10) and PM(2.5) identified several volatile and semi-volatile organic compounds, the presence of carcinogenic aromatic compounds and traces of flame retardants. This interdisciplinary and multi-analytical investigation aims to provide an improved understanding of reported adverse health effects induced by subway aerosols. Copyright © 2012 Elsevier B.V. All rights reserved.

  18. Mechanical characterization of diesel soot nanoparticles: in situ compression in a transmission electron microscope and simulations

    NASA Astrophysics Data System (ADS)

    Jenei, Istvan Zoltan; Dassenoy, Fabrice; Epicier, Thierry; Khajeh, Arash; Martini, Ashlie; Uy, Dairene; Ghaednia, Hamed; Gangopadhyay, Arup

    2018-02-01

    Incomplete fuel burning inside an internal combustion engine results in the creation of soot in the form of nanoparticles. Some of these soot nanoparticles (SNP) become adsorbed into the lubricating oil film present on the cylinder walls, which adversely affects the tribological performance of the lubricant. In order to better understand the mechanisms underlying the wear caused by SNPs, it is important to understand the behavior of SNPs and to characterize potential changes in their mechanical properties (e.g. hardness) caused by (or during) mechanical stress. In this study, the behavior of individual SNPs originating from diesel engines was studied under compression. The experiments were performed in a transmission electron microscope using a nanoindentation device. The nanoparticles exhibited elasto-plastic behavior in response to consecutive compression cycles. From the experimental data, the Young’s modulus and hardness of the SNPs were calculated. The Young’s modulus and hardness of the nanoparticles increased with the number of compression cycles. Using an electron energy loss spectroscopy technique, it was shown that the sp2/sp3 ratio within the compressed nanoparticle decreases, which is suggested to be the cause of the increase in elasticity and hardness. In order to corroborate the experimental findings, molecular dynamics simulations of a model SNP were performed. The SNP model was constructed using carbon and hydrogen atoms with morphology and composition comparable to those observed in the experiment. The model SNP was subjected to repeated compressions between two virtual rigid walls. During the simulation, the nanoparticle exhibited elasto-plastic behavior like that in the experiments. The results of the simulations confirm that the increase in the elastic modulus and hardness is associated with a decrease in the sp2/sp3 ratio.

  19. Mechanical characterization of diesel soot nanoparticles: in situ compression in a transmission electron microscope and simulations.

    PubMed

    Jenei, Istvan Zoltan; Dassenoy, Fabrice; Epicier, Thierry; Khajeh, Arash; Martini, Ashlie; Uy, Dairene; Ghaednia, Hamed; Gangopadhyay, Arup

    2018-02-23

    Incomplete fuel burning inside an internal combustion engine results in the creation of soot in the form of nanoparticles. Some of these soot nanoparticles (SNP) become adsorbed into the lubricating oil film present on the cylinder walls, which adversely affects the tribological performance of the lubricant. In order to better understand the mechanisms underlying the wear caused by SNPs, it is important to understand the behavior of SNPs and to characterize potential changes in their mechanical properties (e.g. hardness) caused by (or during) mechanical stress. In this study, the behavior of individual SNPs originating from diesel engines was studied under compression. The experiments were performed in a transmission electron microscope using a nanoindentation device. The nanoparticles exhibited elasto-plastic behavior in response to consecutive compression cycles. From the experimental data, the Young's modulus and hardness of the SNPs were calculated. The Young's modulus and hardness of the nanoparticles increased with the number of compression cycles. Using an electron energy loss spectroscopy technique, it was shown that the sp 2 /sp 3 ratio within the compressed nanoparticle decreases, which is suggested to be the cause of the increase in elasticity and hardness. In order to corroborate the experimental findings, molecular dynamics simulations of a model SNP were performed. The SNP model was constructed using carbon and hydrogen atoms with morphology and composition comparable to those observed in the experiment. The model SNP was subjected to repeated compressions between two virtual rigid walls. During the simulation, the nanoparticle exhibited elasto-plastic behavior like that in the experiments. The results of the simulations confirm that the increase in the elastic modulus and hardness is associated with a decrease in the sp 2 /sp 3 ratio.

  20. Evaluation and optimisation of phenomenological multi-step soot model for spray combustion under diesel engine-like operating conditions

    NASA Astrophysics Data System (ADS)

    Pang, Kar Mun; Jangi, Mehdi; Bai, Xue-Song; Schramm, Jesper

    2015-05-01

    In this work, a two-dimensional computational fluid dynamics study is reported of an n-heptane combustion event and the associated soot formation process in a constant volume combustion chamber. The key interest here is to evaluate the sensitivity of the chemical kinetics and submodels of a semi-empirical soot model in predicting the associated events. Numerical computation is performed using an open-source code and a chemistry coordinate mapping approach is used to expedite the calculation. A library consisting of various phenomenological multi-step soot models is constructed and integrated with the spray combustion solver. Prior to the soot modelling, combustion simulations are carried out. Numerical results show that the ignition delay times and lift-off lengths exhibit good agreement with the experimental measurements across a wide range of operating conditions, apart from those in the cases with ambient temperature lower than 850 K. The variation of the soot precursor production with respect to the change of ambient oxygen levels qualitatively agrees with that of the conceptual models when the skeletal n-heptane mechanism is integrated with a reduced pyrene chemistry. Subsequently, a comprehensive sensitivity analysis is carried out to appraise the existing soot formation and oxidation submodels. It is revealed that the soot formation is captured when the surface growth rate is calculated using a square root function of the soot specific surface area and when a pressure-dependent model constant is considered. An optimised soot model is then proposed based on the knowledge gained through this exercise. With the implementation of optimised model, the simulated soot onset and transport phenomena before reaching quasi-steady state agree reasonably well with the experimental observation. Also, variation of spatial soot distribution and soot mass produced at oxygen molar fractions ranging from 10.0 to 21.0% for both low and high density conditions are reproduced.

  1. Tackling a Hot Paradox: Laminar Soot Processes-2 (LSP-2)

    NASA Technical Reports Server (NTRS)

    Faeth, Gerard M.; Urban, David L.; Over, Ann (Technical Monitor)

    2002-01-01

    The last place you want to be in traffic is behind the bus or truck that is belching large clouds of soot onto your freshly washed car. Besides looking and smelling bad, soot is a health hazard. Particles range from big enough to see to microscopic and can accumulate in the lungs, potentially leading to debilitating or fatal lung diseases. Soot is wasted energy, and therein lies an interesting paradox: Soot forms in a flame's hottest regions where you would expect complete combustion and no waste. Soot enhances the emissions of other pollutants (carbon monoxide and polyaromatic hydrocarbons, etc.) from flames and radiates unwanted heat to combustion chambers (a candle's yellowish glow is soot radiating heat), among other effects. The mechanisms of soot formation are among the most important unresolved problems of combustion science because soot affects contemporary life in so many ways. Although we have used fire for centuries, many fundamental aspects of combustion remain elusive, in part because of limits imposed by the effects of gravity on Earth. Hot or warm air rises quickly and draws in fresh cold air behind it, thus giving flames the classical teardrop shape. Reactions occur in a very small zone, too fast for scientists to observe, in detail, what is happening inside the flame. The Laminar Soot Processes (LSP-2) experiments aboard STS-107 will use the microgravity environment of space to eliminate buoyancy effects and thus slow the reactions inside a flame so they can be more readily studied. 'Laminar' means a simple, smooth fuel jet burning in air, somewhat like a butane lighter. This classical flame approximates combustion in diesel engines, aircraft jet propulsion engines, and furnaces and other devices. LSP-2 will expand on surprising results developed from its first two flights in 1997. The data suggest the existence of a universal relationship, the soot paradigm, that, if proven, will be used to model and control combustion systems on Earth. STS-107

  2. Oxidation characteristics of gasoline direct-injection (GDI) engine soot: Catalytic effects of ash and modified kinetic correlation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Choi, Seungmok; Seong, Heeje

    In this paper, experimental analyses are conducted into the GDI soot oxidation characteristics as dependent on engine operating conditions. Soot is sampled at various engine operating conditions of a commercial 2.4 L GDI engine with a naturally aspirated, homogeneous, and stoichiometric operation strategy. The oxidation reactivity, ash composition, and carbon nanostructure of the GDI soot samples are analyzed using thermogravimetric analysis (TGA), scanning electron microscope–energy-dispersive spectroscopy (SEM-EDS), high-resolution transmission electron microscopy (HR-TEM), and Raman spectroscopy. Based on the analyses, a global GDI soot oxidation mechanism is proposed which includes the effects of soluble organic fractions (SOF)/weakly bonded carbon (WBC), andmore » three types of ash on GDI soot oxidation. The results show that GDI soot contains an order of magnitude higher ash fraction than does conventional diesel soot, and oxidation reactivity is significantly enhanced by the catalytic effects of ash, as a function of ash content in soot. A modified empirical kinetic correlation for GDI soot oxidation is suggested on the basis of the results, and the modified kinetic correlation predicts the GDI soot oxidation rate accurately for various engine operation points at wide ranges of soot conversion and temperature without modifying kinetic parameters. The kinetic parameters are determined from isothermal and non-isothermal thremogravimetric analysis (TGA) soot oxidation tests; the methods are elucidated in detail.« less

  3. Oxidation characteristics of gasoline direct-injection (GDI) engine soot: Catalytic effects of ash and modified kinetic correlation

    DOE PAGES

    Choi, Seungmok; Seong, Heeje

    2015-03-02

    In this paper, experimental analyses are conducted into the GDI soot oxidation characteristics as dependent on engine operating conditions. Soot is sampled at various engine operating conditions of a commercial 2.4 L GDI engine with a naturally aspirated, homogeneous, and stoichiometric operation strategy. The oxidation reactivity, ash composition, and carbon nanostructure of the GDI soot samples are analyzed using thermogravimetric analysis (TGA), scanning electron microscope–energy-dispersive spectroscopy (SEM-EDS), high-resolution transmission electron microscopy (HR-TEM), and Raman spectroscopy. Based on the analyses, a global GDI soot oxidation mechanism is proposed which includes the effects of soluble organic fractions (SOF)/weakly bonded carbon (WBC), andmore » three types of ash on GDI soot oxidation. The results show that GDI soot contains an order of magnitude higher ash fraction than does conventional diesel soot, and oxidation reactivity is significantly enhanced by the catalytic effects of ash, as a function of ash content in soot. A modified empirical kinetic correlation for GDI soot oxidation is suggested on the basis of the results, and the modified kinetic correlation predicts the GDI soot oxidation rate accurately for various engine operation points at wide ranges of soot conversion and temperature without modifying kinetic parameters. The kinetic parameters are determined from isothermal and non-isothermal thremogravimetric analysis (TGA) soot oxidation tests; the methods are elucidated in detail.« less

  4. Environmental implications of iron fuel borne catalysts and their effects on diesel particulate formation and composition

    EPA Science Inventory

    Metal fuel borne catalysts can be used with diesel fuels to effectively reduce engine out particle mass emissions. Mixed with the fuel, the metals become incorporated as nanometer-scale occlusions with soot during its formation and are available to promote in-cylinder soot oxida...

  5. Effect of Morphology and Composition on the Hygroscopicity of Soot Aerosols

    NASA Astrophysics Data System (ADS)

    Williams, L.; Slowik, J.; Davidovits, P.; Jayne, J.; Kolb, C.; Worsnop, D.; Rudich, Y.

    2003-12-01

    , independent of the mobility diameter. This type of constancy of the aerodynamic diameter has been observed for soot particles in diesel engine exhaust and has been interpreted in terms of a size-dependent effective density. The soot chemical composition is also altered. In this soot the organics are mainly linear hydrocarbons. The differences between these two types of soot with respect to hygroscopicity and effective area are being investigated.

  6. Effect of compression ratio, nozzle opening pressure, engine load, and butanol addition on nanoparticle emissions from a non-road diesel engine.

    PubMed

    Maurya, Rakesh Kumar; Saxena, Mohit Raj; Rai, Piyush; Bhardwaj, Aashish

    2018-05-01

    Currently, diesel engines are more preferred over gasoline engines due to their higher torque output and fuel economy. However, diesel engines confront major challenge of meeting the future stringent emission norms (especially soot particle emissions) while maintaining the same fuel economy. In this study, nanosize range soot particle emission characteristics of a stationary (non-road) diesel engine have been experimentally investigated. Experiments are conducted at a constant speed of 1500 rpm for three compression ratios and nozzle opening pressures at different engine loads. In-cylinder pressure history for 2000 consecutive engine cycles is recorded and averaged data is used for analysis of combustion characteristics. An electrical mobility-based fast particle sizer is used for analyzing particle size and mass distributions of engine exhaust particles at different test conditions. Soot particle distribution from 5 to 1000 nm was recorded. Results show that total particle concentration decreases with an increase in engine operating loads. Moreover, the addition of butanol in the diesel fuel leads to the reduction in soot particle concentration. Regression analysis was also conducted to derive a correlation between combustion parameters and particle number emissions for different compression ratios. Regression analysis shows a strong correlation between cylinder pressure-based combustion parameters and particle number emission.

  7. Susceptibility of contrail ice crystal numbers to aircraft soot particle emissions

    NASA Astrophysics Data System (ADS)

    Kärcher, B.; Voigt, C.

    2017-08-01

    We develop an idealized, physically based model describing combined effects of ice nucleation and sublimation on ice crystal number during persistent contrail formation. Our study represents the first effort to predict ice numbers at the point where contrails transition into contrail cirrus—several minutes past formation—by connecting them to aircraft soot particle emissions and atmospheric supersaturation with respect to ice. Results averaged over an observed exponential distribution of ice supersaturation (mean value 15%) indicate that large reductions in soot particle numbers are needed to lower contrail ice crystal numbers significantly for soot emission indices around 1015 (kg fuel)-1, because reductions in nucleated ice number are partially compensated by sublimation losses. Variations in soot particle (-50%) and water vapor (+10%) emission indices at threefold lower soot emissions resulting from biofuel blending cause ice crystal numbers to change by -35% and <5%, respectively. The efficiency of reduction depends on ice supersaturation and the size distribution of nucleated ice crystals in jet exhaust plumes and on atmospheric ice supersaturation, making the latter another key factor in contrail mitigation. We expect our study to have important repercussions for planning airborne measurements targeting contrail formation, designing parameterization schemes for use in large-scale models, reducing uncertainties in predicting contrail cirrus, and mitigating the climate impact of aviation.

  8. Impact of rail pressure and biodiesel fueling on the particulate morphology and soot nanostructures from a common-rail turbocharged direct injection diesel engine

    DOE PAGES

    Ye, Peng; Vander Wal, Randy; Boehman, Andre L.; ...

    2014-12-26

    The effect of rail pressure and biodiesel fueling on the morphology of exhaust particulate agglomerates and the nanostructure of primary particles (soot) was investigated with a common-rail turbocharged direct injection diesel engine. The engine was operated at steady state on a dynamometer running at moderate speed with both low (30%) and medium–high (60%) fixed loads, and exhaust particulate was sampled for analysis. Ultra-low sulfur diesel and its 20% v/v blends with soybean methyl ester biodiesel were used. Fuel injection occurred in a single event around top dead center at three different injection pressures. Exhaust particulate samples were characterized with TEMmore » imaging, scanning mobility particle sizing, thermogravimetric analysis, Raman spectroscopy, and XRD analysis. Particulate morphology and oxidative reactivity were found to vary significantly with rail pressure and with biodiesel blend level. Higher biodiesel content led to increases in the primary particle size and oxidative reactivity but did not affect nanoscale disorder in the as-received samples. For particulates generated with higher injection pressures, the initial oxidative reactivity increased, but there was no detectable correlation with primary particle size or nanoscale disorder.« less

  9. Impact of rail pressure and biodiesel fueling on the particulate morphology and soot nanostructures from a common-rail turbocharged direct injection diesel engine

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ye, Peng; Vander Wal, Randy; Boehman, Andre L.

    The effect of rail pressure and biodiesel fueling on the morphology of exhaust particulate agglomerates and the nanostructure of primary particles (soot) was investigated with a common-rail turbocharged direct injection diesel engine. The engine was operated at steady state on a dynamometer running at moderate speed with both low (30%) and medium–high (60%) fixed loads, and exhaust particulate was sampled for analysis. Ultra-low sulfur diesel and its 20% v/v blends with soybean methyl ester biodiesel were used. Fuel injection occurred in a single event around top dead center at three different injection pressures. Exhaust particulate samples were characterized with TEMmore » imaging, scanning mobility particle sizing, thermogravimetric analysis, Raman spectroscopy, and XRD analysis. Particulate morphology and oxidative reactivity were found to vary significantly with rail pressure and with biodiesel blend level. Higher biodiesel content led to increases in the primary particle size and oxidative reactivity but did not affect nanoscale disorder in the as-received samples. For particulates generated with higher injection pressures, the initial oxidative reactivity increased, but there was no detectable correlation with primary particle size or nanoscale disorder.« less

  10. Influence of low-temperature combustion and dimethyl ether-diesel blends on performance, combustion, and emission characteristics of common rail diesel engine: a CFD study.

    PubMed

    Lamani, Venkatesh Tavareppa; Yadav, Ajay Kumar; Narayanappa, Kumar Gottekere

    2017-06-01

    Due to presence of more oxygen, absence of carbon-carbon (C-C) bond in chemical structure, and high cetane number of dimethyl ether (DME), pollution from DME operated engine is less compared to diesel engine. Hence, the DME can be a promising alternative fuel for diesel engine. The present study emphasizes the effect of various exhaust gas recirculation (EGR) rates (0-20%) and DME/Diesel blends (0-20%) on combustion characteristics and exhaust emissions of common rail direct injection (CRDI) engine using three-dimensional computational fluid dynamics (CFD) simulation. Extended coherent flame model-3 zone (ECFM-3Z) is implemented to carry out combustion analysis, and k-ξ-f model is employed for turbulence modeling. Results show that in-cylinder pressure marginally decreases with employing EGR compared to without EGR case. As EGR rate increases, nitrogen oxide (NO) formation decreases, whereas soot increases marginally. Due to better combustion characteristics of DME, indicated thermal efficiency (ITE) increases with the increases in DME/diesel blend ratio. Adverse effect of EGR on efficiency for blends is less compared to neat diesel, because the anoxygenated region created due to EGR is compensated by extra oxygen present in DME. The trade-off among NO, soot, carbon monoxide (CO) formation, and efficiency is studied by normalizing the parameters. Optimum operating condition is found at 10% EGR rate and 20% DME/diesel blend. The maximum indicated thermal efficiency was observed for DME/diesel ratio of 20% in the present range of study. Obtained results are validated with published experimental data and found good agreement.

  11. Electron Microscopic and Spectroscopic Characterization for Soot Source Differentiation by Laser Derivatization

    NASA Astrophysics Data System (ADS)

    Gaddam, Chethan K.

    Combustion produced soot is highly variable with nanostructure and chemistry dependent upon combustion conditions and fuel. Previous studies have shown soot nanostructure to be dependent upon the source via quantification of high-resolution transmission electron microscopy (HRTEM) images for nanostructural parameters. In principle this permits identification of the soot source and its contribution to any particular receptor site. Yet many structural aspects are subtle, and the chemistry of lamellae is unaddressed for reasons of poorly resolved or differentiated nanostructure and insufficient sample quantity for traditional analytical methods. This characterization gap then leads to the formative question prompting this study: how best to bring out small differences in nanostructure and other seemingly subtle differences in chemistry? A process of pulsed laser annealing is proposed to highlight compositional and structural differences thereby distinctively and uniquely identifying the source of the soot. The operative premise being that small variations in nanostructure and unresolved differences in chemistry exist and are specific to the particular combustion process. The overall goal is then to develop the laser-based heating as an analytical tool by identifying the process conditions and operational parameters for optimal derivatization. Specific objectives directed towards achieving this goal include: 1) Identifying optimal laser operational parameters for derivatization. 2) Defining the dependence upon nanostructure and molecular composition using model soots while also identifying variability and range of outcomes. 3) Demonstrating differentiation upon combustion derived soots from real engines, e.g. diesel, gasoline, gas-turbines, combustors, etc. 4) Applying image processing algorithms to the laser heated soots to quantify and differentiate the transformed carbon nanostructures. For laser derivatization, a sample-housing chamber was custom built using a

  12. Sooting turbulent jet flame: characterization and quantitative soot measurements

    NASA Astrophysics Data System (ADS)

    Köhler, M.; Geigle, K. P.; Meier, W.; Crosland, B. M.; Thomson, K. A.; Smallwood, G. J.

    2011-08-01

    Computational fluid dynamics (CFD) modelers require high-quality experimental data sets for validation of their numerical tools. Preferred features for numerical simulations of a sooting, turbulent test case flame are simplicity (no pilot flame), well-defined boundary conditions, and sufficient soot production. This paper proposes a non-premixed C2H4/air turbulent jet flame to fill this role and presents an extensive database for soot model validation. The sooting turbulent jet flame has a total visible flame length of approximately 400 mm and a fuel-jet Reynolds number of 10,000. The flame has a measured lift-off height of 26 mm which acts as a sensitive marker for CFD model validation, while this novel compiled experimental database of soot properties, temperature and velocity maps are useful for the validation of kinetic soot models and numerical flame simulations. Due to the relatively simple burner design which produces a flame with sufficient soot concentration while meeting modelers' needs with respect to boundary conditions and flame specifications as well as the present lack of a sooting "standard flame", this flame is suggested as a new reference turbulent sooting flame. The flame characterization presented here involved a variety of optical diagnostics including quantitative 2D laser-induced incandescence (2D-LII), shifted-vibrational coherent anti-Stokes Raman spectroscopy (SV-CARS), and particle image velocimetry (PIV). Producing an accurate and comprehensive characterization of a transient sooting flame was challenging and required optimization of these diagnostics. In this respect, we present the first simultaneous, instantaneous PIV, and LII measurements in a heavily sooting flame environment. Simultaneous soot and flow field measurements can provide new insights into the interaction between a turbulent vortex and flame chemistry, especially since soot structures in turbulent flames are known to be small and often treated in a statistical manner.

  13. Application of an Ir tracer to determine soot exposure to students commuting to school on Baltimore public buses

    NASA Astrophysics Data System (ADS)

    Wu, Charles C.; Suarez, Ana E.; Lin, Zhibo; Kidwell, Christopher B.; Borgoul, Polina V.; Caffrey, Peter F.; Ondov, John M.; Sattler, Barbara

    An important component of urban aerosol, diesel soot is a known respiratory irritant and contains mutagenic and carcinogenic organic compounds. To estimate student exposures to soot emitted from public diesel buses during commutes to city high schools, a portion of the Baltimore municipal fuel supply was tagged with an iridium tracer and exposure was monitored during commutes with personal aerosol monitors as a part of an Environmental Justice Project. A total of 68.2 g of Ir as iridium(III)-2,4-pentanedionate were used to induce a concentration of 48.5 μg Ir ℓ -1 of fuel. Twenty samples were collected over 10 days while four students commuted on regularly scheduled buses and a fifth student commuted by private car. Individual samples integrated from 1 to 4 round trips. Iridium analyses were performed instrumentally after neutron activation with a detection limit (DL) of about 500 fg. For students commuting by bus and following protocols, Ir tracer concentrations ranged from 53±38 to >1980±49 fg m -3. Concentrations up to 3530±220 fg m -3 were observed for student #5, who sampled only when boarding and disembarking. Exposure were greatest for students commuting through the heavily trafficked central business district. Corresponding estimates of exposures to soot emitted from municipal buses ranged from ⩽3 to 82 ng soot m -3 (⩽145 ng m -3 for student #5), i.e. well below the exposure level of 2-10 μg m -3 total C from all sources, including the more than 30,000 diesel trucks which pass through the city's major toll facilities each day. Ir was undetectable in samples collected by the student commuting by car when its windows were closed, but comparable to those of the other students when commutes were made with windows open. The Ir tracer DL corresponds to about 21 ng soot, about half of which is carbon. This is far below the 230 ng reported for analysis by a highly sensitive thermal-optical technique.

  14. Distinct oxidative stabilities of char versus soot black carbon: Implications for quantification and environmental recalcitrance

    NASA Astrophysics Data System (ADS)

    Elmquist, Marie; Cornelissen, Gerard; Kukulska, Zofia; Gustafsson, Örjan

    2006-06-01

    Sequestration in sediments of black carbon (BC) from vegetation fires and fuel combustion may constitute a significant sink of otherwise rapidly cycling carbon from the atmosphere-biosphere cycle. It also has the potential to provide a historical record of atmospheric BC loadings. Previous treatments of BC as one homogeneous entity are being replaced with the growing awareness of a BC combustion continuum, a range spanning from slightly charred biomass to soot and graphite. Here the relative recalcitrance of different BC forms is evaluated, and implications for both BC quantification and environmental stability are considered. The stabilities of four BC reference materials against thermal oxidation in air were quite distinct with T50%BC values (i.e., the temperature where 50% BC remained in the residue) of 444°C (diesel soot-BC), 388°C (n-hexane soot-BC), 338°C (wood char-BC), and 266°C (grass char-BC). The implications for BC quantification have been illustrated for a thermal oxidation (the CTO-375) method commonly applied to study BC in sediments. This technique measured BC:TOC ratios of 78.3 ± 1.3% for the diesel soot-BC and 45.3 ± 6.1% for n-hexane soot-BC, whereas no CTO375-BC was detected for the two analyzed char-BC materials. The greater lability of char-BC compared to soot-BC likely reflects higher accessibility to internal microporosity in char-BC, facilitating internal O2 transfer. Decreasing the temperature cutoff below 375°C to also include char-BC is not possible as thermograms of nonpyrogenic reference materials indicated that such material would then be artifactually quantified as BC. The presence of mineral oxides in the sediment matrix may lead to a catalytically mediated lowering of the activation energy for soot-BC oxidation but not for char-BC or nonpyrogenic organic material. Several recent studies combine to challenge the proposition of complete recalcitrance of BC. Particularly, the thermal lability of char-BC from grassland fires

  15. Trace Metals in Soot and PM2.5 from Heavy-Fuel-Oil Combustion in a Marine Engine

    PubMed Central

    2018-01-01

    Heavy fuel oil (HFO) particulate matter (PM) emitted by marine engines is known to contain toxic heavy metals, including vanadium (V) and nickel (Ni). The toxicity of such metals will depend on the their chemical state, size distribution, and mixing state. Using online soot-particle aerosol mass spectrometry (SP-AMS), we quantified the mass of five metals (V, Ni, Fe, Na, and Ba) in HFO-PM soot particles produced by a marine diesel research engine. The in-soot metal concentrations were compared to in-PM2.5 measurements by inductively coupled plasma-optical emission spectroscopy (ICP-OES). We found that <3% of total PM2.5 metals was associated with soot particles, which may still be sufficient to influence in-cylinder soot burnout rates. Since these metals were most likely present as oxides, whereas studies on lower-temperature boilers report a predominance of sulfates, this result implies that the toxicity of HFO PM depends on its combustion conditions. Finally, we observed a 4-to-25-fold enhancement in the ratio V:Ni in soot particles versus PM2.5, indicating an enrichment of V in soot due to its lower nucleation/condensation temperature. As this enrichment mechanism is not dependent on soot formation, V is expected to be generally enriched within smaller HFO-PM particles from marine engines, enhancing its toxicity. PMID:29688717

  16. Soot Optical Property Study

    NASA Technical Reports Server (NTRS)

    Aung, K. T.; Hassan, M. I.; Krishnan, S. S.; Lin, K.-C.; Xu, F.; Faeth, G. M.; Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

    2001-01-01

    Recent past studies of soot reaction processes in laminar premixed and nonpremixed flames generally have used the intrusive technique of thermophoretic sampling and analysis by transmission electron microscopy (TEM) to observe soot structure and obtain important fundamental information about soot particle properties, such as soot primary particle diameters, the rate of change of soot primary particle diameter as a function of time (or rate of soot surface growth or oxidation), the amount of soot particle reactive surface area per unit volume, the number of primary soot particles per unit volume, and the rate of formation of primary soot particles (or the rate of soot primary particle nucleation). Given the soot volume per unit volume of the flame (or the soot volume fraction), all these properties are readily found from a measurement of the soot primary particle diameter (which usually is nearly a constant for each location within a laminar flame). This approach is not possible within freely propagating flames, however, because soot properties at given positions in such flames vary relatively rapidly as a function of time in the soot formation and oxidation regions compared to the relatively lengthy sampling times needed to accumulate adequate soot samples and to minimize effects of soot collected on the sampling grid as it moves to and from the sampling position through other portions of the flame. Thus, nonintrusive optical methods must be used to find the soot primary particle diameters needed to define the soot surface reaction properties mentioned earlier. Unfortunately, approximate nonintrusive methods used during early studies of soot reaction properties in flames, found from laser scattering and absorption measurements analyzed assuming either Rayleigh scattering or Mie scattering from polydisperse effective soot particles having the same mass of soot as individual soot aggregates, have not been found to be an effective way to estimate the soot surface

  17. Soot Aerosol Properties in Laminar Soot-Emitting Microgravity Nonpremixed Flames

    NASA Technical Reports Server (NTRS)

    Konsur, Bogdan; Megaridis, Constantine M.; Griffin, Devon W.

    1999-01-01

    The spatial distributions and morphological properties of the soot aerosol are examined experimentally in a series of 0-g laminar gas-jet nonpremixed flames. The methodology deploys round jet diffusion flames of nitrogen-diluted acetylene fuel burning in quiescent air at atmospheric pressure. Full-field laser-light extinction is utilized to determine transient soot spatial distributions within the flames. Thermophoretic sampling is employed in conjunction with transmission electron microscopy to define soot microstructure within the soot-emitting 0-g flames. The microgravity tests indicate that the 0-g flames attain a quasi-steady state roughly 0.7 s after ignition, and sustain their annular structure even beyond their luminous flame tip. The measured peak soot volume fractions show a complex dependence on burner exit conditions, and decrease in a nonlinear fashion with decreasing characteristic flow residence times. Fuel preheat by approximately 140 K appears to accelerate the formation of soot near the flame axis via enhanced fuel pyrolysis rates. The increased soot presence caused by the elevated fuel injection temperatures triggers higher flame radiative losses, which may account for the premature suppression of soot growth observed along the annular region of preheated-fuel flames. Electron micrographs of soot aggregates collected in 0-g reveal the presence of soot precursor particles near the symmetry axis at midflame height, The observations also verify that soot primary particle sizes are nearly uniform among aggregates present at the same flame location, but vary considerably with radius at a fixed distance from the burner. The maximum primary size in 0-g is found to be by 40% larger than in 1-g, under the same burner exit conditions. Estimates of the number concentration of primary particles and surface area of soot particulate phase per unit volume of the combustion gases are also made for selected in-flame locations.

  18. Fuel Efficient Diesel Particulate Filter (DPF) Modeling and Development

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Stewart, Mark L.; Gallant, Thomas R.; Kim, Do Heui

    The project described in this report seeks to promote effective diesel particulate filter technology with minimum fuel penalty by enhancing fundamental understanding of filtration mechanisms through targeted experiments and computer simulations. The overall backpressure of a filtration system depends upon complex interactions of particulate matter and ash with the microscopic pores in filter media. Better characterization of these phenomena is essential for exhaust system optimization. The acicular mullite (ACM) diesel particulate filter substrate is under continuing development by Dow Automotive. ACM is made up of long mullite crystals which intersect to form filter wall framework and protrude from the wallmore » surface into the DPF channels. ACM filters have been demonstrated to effectively remove diesel exhaust particles while maintaining relatively low backpressure. Modeling approaches developed for more conventional ceramic filter materials, such as silicon carbide and cordierite, have been difficult to apply to ACM because of properties arising from its unique microstructure. Penetration of soot into the high-porosity region of projecting crystal structures leads to a somewhat extended depth filtration mode, but with less dramatic increases in pressure drop than are normally observed during depth filtration in cordierite or silicon carbide filters. Another consequence is greater contact between the soot and solid surfaces, which may enhance the action of some catalyst coatings in filter regeneration. The projecting crystals appear to provide a two-fold benefit for maintaining low backpressures during filter loading: they help prevent soot from being forced into the throats of pores in the lower porosity region of the filter wall, and they also tend to support the forming filter cake, resulting in lower average cake density and higher permeability. Other simulations suggest that soot deposits may also tend to form at the tips of projecting crystals due to

  19. Experimental investigation of submicron and ultrafine soot particle removal by tree leaves

    NASA Astrophysics Data System (ADS)

    Hwang, Hee-Jae; Yook, Se-Jin; Ahn, Kang-Ho

    2011-12-01

    Soot particles emitted from vehicles are one of the major sources of air pollution in urban areas. In this study, five kinds of trees were selected as Pinus densiflora, Taxus cuspidata, Platanus occidentalis, Zelkova serrata, and Ginkgo biloba, and the removal of submicron (<1 μm) and ultrafine (<0.1 μm) soot particles by tree leaves was quantitatively compared in terms of deposition velocity. Soot particles were produced by a diffusion flame burner using acetylene as the fuel. The sizes of monodisperse soot particles classified with the Differential Mobility Analyzers (DMA) were 30, 55, 90, 150, 250, 400, and 600 nm. A deposition chamber was designed to simulate the omni-directional flow condition around the tree leaves. Deposition velocities onto the needle-leaf trees were higher than those onto the broadleaf trees. P. densiflora showed the greatest deposition velocity, followed by T. cuspidata, Platanus occidentalis, Zelkova serrata, and Ginkgo biloba. In addition, from the comparison of deposition velocity between two groups of Platanus occidentalis leaves, i.e. one group of leaves with front sides only and the other with back sides only, it was supposed in case of the broadleaf trees that the removal of airborne soot particles of submicron and ultrafine sizes could be affected by the surface roughness of tree leaves, i.e. the veins and other structures on the leaves.

  20. Plasma flame for mass purification of contaminated air with chemical and biological warfare agents

    NASA Astrophysics Data System (ADS)

    Uhm, Han S.; Shin, Dong H.; Hong, Yong C.

    2006-09-01

    An elimination of airborne simulated chemical and biological warfare agents was carried out by making use of a plasma flame made of atmospheric plasma and a fuel-burning flame, which can purify the interior air of a large volume in isolated spaces such as buildings, public transportation systems, and military vehicles. The plasma flame generator consists of a microwave plasma torch connected in series to a fuel injector and a reaction chamber. For example, a reaction chamber, with the dimensions of a 22cm diameter and 30cm length, purifies an airflow rate of 5000lpm contaminated with toluene (the simulated chemical agent) and soot from a diesel engine (the simulated aerosol for biological agents). Large volumes of purification by the plasma flame will free mankind from the threat of airborne warfare agents. The plasma flame may also effectively purify air that is contaminated with volatile organic compounds, in addition to eliminating soot from diesel engines as an environmental application.

  1. Carbon nanotube-like materials in the exhaust from a diesel engine using gas oil/ethanol mixing fuel with catalysts and sulfur.

    PubMed

    Suzuki, Shunsuke; Mori, Shinsuke

    2017-08-01

    Particulate matter from a diesel engine, including soot and carbon nanomaterials, was collected on a sampling holder and the structure of the materials was studied by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). As a result of employing gas oil/ethanol mixing fuel with sulfur and ferrocene/molybdenum as catalyst sources, formation of carbon nanotubes (CNT)-like materials in addition to soot was observed in the exhaust gas from a diesel engine. It was revealed that CNT-like materials were included among soot in our system only when the following three conditions were satisfied simultaneously: high ethanol fraction in fuel, high sulfur loading, and presence of catalyst sources in fuel. This study confirmed that if at least one of these three conditions was not satisfied, CNT-like materials were not observed in the exhaust from a diesel engine. These experimental results shown in this work provide insights into understanding CNT-like material formation mechanism in a diesel engine. Recent papers reported that carbon nanotube-like materials were included in the exhaust gas from engines, but conditions for carbon nanotube-like material formation have not been well studied. This work provides the required conditions for carbon nanotube-like material growth in a diesel engine, and this will be helpful for understanding the carbon nanotube-like material formation mechanism and taking countermeasures to preventing carbon nanotube-like material formation in a diesel engine.

  2. Experimental study on particulate and NOx emissions of a diesel engine fueled with ultra low sulfur diesel, RME-diesel blends and PME-diesel blends.

    PubMed

    Zhu, Lei; Zhang, Wugao; Liu, Wei; Huang, Zhen

    2010-02-01

    Ultra low sulfur diesel and two different kinds of biodiesel fuels blended with baseline diesel fuel in 5% and 20% v/v were tested in a Cummins 4BTA direct injection diesel engine, with a turbocharger and an intercooler. Experiments were conducted under five engine loads at two steady speeds (1500 rpm and 2500 rpm). The study aims at investigating the engine performance, NO(x) emission, smoke opacity, PM composition, PM size distribution and comparing the impacts of low sulfur content of biodiesel with ULSD on the particulate emission. The results indicate that, compared to base diesel fuel, the increase of biodiesel in blends could cause certain increase in both brake specific fuel consumption and brake thermal efficiency. Compared with baseline diesel fuel, the biodiesel blends bring about more NO(x) emissions. With the proportion of biodiesel increase in blends, the smoke opacity decreases, while total particle number concentration increases. Meanwhile the ULSD gives lower NO(x) emissions, smoke opacity and total number concentration than those of baseline diesel fuel. In addition, the percentages of SOF and sulfate in particulates increase with biodiesel in blends, while the dry soot friction decreases obviously. Compared with baseline diesel fuel, the biodiesel blends increase the total nucleation number concentration, while ULSD reduces the total nucleation number concentration effectively, although they all have lower sulfur content. It means that, for ULSD, the lower sulfur content is the dominant factor for suppressing nucleation particles formation, while for biodiesel blends, lower volatile, lower aromatic content and higher oxygen content of biodiesel are key factors for improving the nucleation particles formation. The results demonstrate that the higher NO(x) emission and total nucleation number concentration are considered as the big obstacles of the application of biodiesel in diesel engine. Copyright 2009 Elsevier B.V. All rights reserved.

  3. FORMATION OF POLYCYCLIC AROMATIC HYDROCARBONS AND THEIR GROWTH TO SOOT -A REVIEW OF CHEMICAL REACTION PATHWAYS. (R824970)

    EPA Science Inventory

    The generation by combustion processes of airborne species of current health concern such as polycyclic aromatic hydrocarbons (PAH) and soot particles necessitates a detailed understanding of chemical reaction pathways responsible for their formation. The present review discus...

  4. First in-flight synchrotron X-ray absorption and photoemission study of carbon soot nanoparticles.

    PubMed

    Ouf, F-X; Parent, P; Laffon, C; Marhaba, I; Ferry, D; Marcillaud, B; Antonsson, E; Benkoula, S; Liu, X-J; Nicolas, C; Robert, E; Patanen, M; Barreda, F-A; Sublemontier, O; Coppalle, A; Yon, J; Miserque, F; Mostefaoui, T; Regier, T Z; Mitchell, J-B A; Miron, C

    2016-11-24

    Many studies have been conducted on the environmental impacts of combustion generated aerosols. Due to their complex composition and morphology, their chemical reactivity is not well understood and new developments of analysis methods are needed. We report the first demonstration of in-flight X-ray based characterizations of freshly emitted soot particles, which is of paramount importance for understanding the role of one of the main anthropogenic particulate contributors to global climate change. Soot particles, produced by a burner for several air-to-fuel ratios, were injected through an aerodynamic lens, focusing them to a region where they interacted with synchrotron radiation. X-ray photoelectron spectroscopy and carbon K-edge near-edge X-ray absorption spectroscopy were performed and compared to those obtained for supported samples. A good agreement is found between these samples, although slight oxidation is observed for supported samples. Our experiments demonstrate that NEXAFS characterization of supported samples provides relevant information on soot composition, with limited effects of contamination or ageing under ambient storage conditions. The highly surface sensitive XPS experiments of airborne soot indicate that the oxidation is different at the surface as compared to the bulk probed by NEXAFS. We also report changes in soot's work function obtained at different combustion conditions.

  5. Ultrafine particle emissions from modern Gasoline and Diesel vehicles: An electron microscopic perspective.

    PubMed

    Liati, Anthi; Schreiber, Daniel; Arroyo Rojas Dasilva, Yadira; Dimopoulos Eggenschwiler, Panayotis

    2018-08-01

    Ultrafine (<100 nm) particles related to traffic are of high environmental and human health concern, as they are supposed to be more toxic than larger particles. In the present study transmission electron microscopy (TEM) is applied to obtain a concrete picture on the nature, morphology and chemical composition of non-volatile ultrafine particles in the exhaust of state-of-the-art, Euro 6b, Gasoline and Diesel vehicles. The particles were collected directly on TEM grids, at the tailpipe, downstream of the after-treatment system, during the entire duration of typical driving cycles on the chassis dynamometer. Based on TEM imaging coupled with Energy Dispersive X-ray (EDX) analysis, numerous ultrafine particles could be identified, imaged and analyzed chemically. Particles <10 nm were rarely detected. The ultrafine particles can be distinguished into the following types: soot, ash-bearing soot and ash. Ash consists of Ca, P, Mg, Zn, Fe, S, and minor Sn compounds. Most elements originate from lubricating oil additives; Sn and at least part of Fe are products of engine wear; minor W ± Si-bearing nearly spherical particles in Diesel exhaust derive from catalytic coating material. Ultrafine ash particles predominate over ultrafine soot or are nearly equal in amount, in contrast to emissions of larger sizes where soot is by far the prevalent particle type. This is probably due to the low ash amount per volume fraction in the total emissions, which does not favor formation of large ash agglomerates, opposite to soot, which is abundant and thus easily forms agglomerates of sizes larger than those of the ultrafine range. No significant differences of ultrafine particle characteristics were identified among the tested Gasoline and Diesel vehicles and driving cycles. The present TEM study gives information also on the imaging and chemical composition of the solid fraction of the unregulated sub-23 nm size category particles. Copyright © 2018 Elsevier Ltd. All

  6. Contribution to the application of two-colour imaging to diesel combustion

    NASA Astrophysics Data System (ADS)

    Payri, F.; Pastor, J. V.; García, J. M.; Pastor, J. M.

    2007-08-01

    The two-colour method (2C) is a well-known methodology for the estimation of flame temperature and the soot-related KL factor. A 2C imaging system has been built with a single charge-coupled device (CCD) camera for visualization of the diesel flame in a single-cylinder 2-stroke engine with optical accesses. The work presented here focuses on methodological aspects. In that sense, the influence of calibration uncertainties on the measured temperature and KL factor has been analysed. Besides, a theoretical study is presented that tries to link the true flame temperature and soot distributions with those derived from the 2C images. Finally, an experimental study has been carried out in order to show the influence of injection pressure, air density and temperature on the 2C-derived parameters. Comparison with the expected results has shown the limitations of this methodology for diesel flame analysis.

  7. Soot

    Cancer.gov

    Learn about soot, which can raise the risk of scrotal and other skin cancers, as well as lung, esophageal, and bladder cancers. Soot is a byproduct of the burning of carbon-containing materials, such as wood, fuel oil, plastics, and household refuse. Chimney sweeps face the highest risk.

  8. Effect of some Turkish vegetable oil-diesel fuel blends on exhaust emissions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ergeneman, M.; Oezaktas, T.; Cigizoglu, K.B.

    1997-10-01

    For different types of vegetable oils of Turkish origin (sunflower, corn, soybean, and olive oil) were blended with grade No. 2-D diesel fuel at a ratio of 20/80 (v/v). The effect of the compression ratio on exhaust emissions is investigated in an American Society for Testing and Materials (ASTM)-cooperative fuel research (CFR) engine working with the mentioned fuel blends and a baseline diesel fuel. A decrease in soot, CO, CO{sub 2}, and HC emissions and an increase in NO{sub x} emissions have been observed for fuel blends compared to diesel fuel.

  9. Soot effects on clouds and solar absorption: Understanding the differences in recently published soot mitigation experiments. (Invited)

    NASA Astrophysics Data System (ADS)

    Bauer, S. E.; Menon, S.

    2010-12-01

    Attention has been drawn to black carbon aerosols, as a target for short-term mitigation of climate warming. This measure seems attractive because soot is assumed to warm the atmosphere and at the same time has a lifetime of just a few days. Therefore regulating soot emissions could, as a short-term action, potentially buy time by slowing global warming until regulations for longer lived greenhouse gases are set in place. Currently the scientific community debates the impacts of such mitigation measures, especially when considering indirect effects. We tested with the GISS/MATRIX model, a global climate model including detailed aerosol microphysics, the effect of reducing fossil fuel emissions and bio-fuel emissions and found that opposite changes in cloud droplet number concentration lead to positive cloud forcing numbers in the bio-fuel reduction case and negative forcing numbers in the diesel mitigation case. Similar experiments have been carried out and have recently been published by other modeling groups, finding partly similar partly contradicting results to our study. In this presentation we want to explain the differences in black carbon research carried out with complex microphysical models, by focusing on the treatment of mixing state, and separation between forcings and feedbacks.

  10. Soot Reaction Properties (Ground-Based Study)

    NASA Technical Reports Server (NTRS)

    Dai, Z.; El-Leathy, A. M.; Lin, K.-C.; Sunderland, P. B.; Xu, F.; Faeth, G. M.; Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

    2000-01-01

    Three major soot reaction processes are needed to predict soot properties in flame environments: soot growth, or the formation of soot on soot nuclei and soot particles; soot oxidation, or the reaction of soot with oxidizing species to yield the combustion products of soot oxidation; and soot nucleation, or the formation of soot nuclei from soot precursors having large molecular weights (generally thought to be large and particularly stable PAH molecules in flame environments, called stabilomers). These processes are addressed in the following, considering soot growth, oxidation and nucleation, in turn, by exploiting the soot and flame structure results for premixed and diffusion flames already discussed in Section 2.

  11. Lube oil-dependent ash chemistry on soot oxidation reactivity in a gasoline direct-injection engine

    DOE PAGES

    Choi, Seungmok; Seong, Heeje

    2016-09-30

    Gasoline particulate filters (GPF) are considered an enabling technology to meet stringent particulate matter (PM) regulations for gasoline direct-injection (GDI) engines, which are known to produce significant PM emissions. While ash loading in filters has been recognized to be detrimental in filter performance by increasing back pressure, increased ash fractions in soot were observed to enhance soot oxidation. In this study, GDI soot samples derived from different gasoline/lube oil blends were evaluated to identify potential promoting factors when formulated lube oils were dosed into gasoline fuel. Ca-derived ash enhanced soot oxidation remarkably, while P- and ZDDP-derived ash deteriorated soot oxidation.more » It is apparent that the promoting effect of lube oil-derived ash is due mainly to the Ca component that is the most abundant among additive components in lube oil. Bulk and surface analyses of these ash compounds indicate that Ca-derived ash would be complex compounds, while the contribution of CaSO 4, which is one of the most abundant ash compounds from diesel engines, is almost negligible. For the validation of the ash promoting impact in filters, the regeneration experiments were compared for a TWC-coated GPF in a GDI engine before and after ash loading was performed. The pressure drop of the ash-loaded GPF decreased noticeably in the initial regeneration stage and it increased gradually, whereas that of no ash-loaded GPF increased gradually without any reduction. So, it is concluded that the ash layer in the GPF assisted soot oxidation in the early regeneration stage when it was in close contact with soot.« less

  12. Lube oil-dependent ash chemistry on soot oxidation reactivity in a gasoline direct-injection engine

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Choi, Seungmok; Seong, Heeje

    Gasoline particulate filters (GPF) are considered an enabling technology to meet stringent particulate matter (PM) regulations for gasoline direct-injection (GDI) engines, which are known to produce significant PM emissions. While ash loading in filters has been recognized to be detrimental in filter performance by increasing back pressure, increased ash fractions in soot were observed to enhance soot oxidation. In this study, GDI soot samples derived from different gasoline/lube oil blends were evaluated to identify potential promoting factors when formulated lube oils were dosed into gasoline fuel. Ca-derived ash enhanced soot oxidation remarkably, while P- and ZDDP-derived ash deteriorated soot oxidation.more » It is apparent that the promoting effect of lube oil-derived ash is due mainly to the Ca component that is the most abundant among additive components in lube oil. Bulk and surface analyses of these ash compounds indicate that Ca-derived ash would be complex compounds, while the contribution of CaSO 4, which is one of the most abundant ash compounds from diesel engines, is almost negligible. For the validation of the ash promoting impact in filters, the regeneration experiments were compared for a TWC-coated GPF in a GDI engine before and after ash loading was performed. The pressure drop of the ash-loaded GPF decreased noticeably in the initial regeneration stage and it increased gradually, whereas that of no ash-loaded GPF increased gradually without any reduction. So, it is concluded that the ash layer in the GPF assisted soot oxidation in the early regeneration stage when it was in close contact with soot.« less

  13. Scattering and radiative properties of complex soot and soot-containing particles

    NASA Astrophysics Data System (ADS)

    Liu, L.; Mishchenko, M. I.; Mackowski, D. W.; Dlugach, J.

    2012-12-01

    Tropospheric soot and soot containing aerosols often exhibit nonspherical overall shapes and complex morphologies. They can externally, semi-externally, and internally mix with other aerosol species. This poses a tremendous challenge in particle characterization, remote sensing, and global climate modeling studies. To address these challenges, we used the new numerically exact public-domain Fortran-90 code based on the superposition T-matrix method (STMM) and other theoretical models to analyze the potential effects of aggregation and heterogeneity on light scattering and absorption by morphologically complex soot containing particles. The parameters we computed include the whole scattering matrix elements, linear depolarization ratios, optical cross-sections, asymmetry parameters, and single scattering albedos. It is shown that the optical characteristics of soot and soot containing aerosols very much depend on particle sizes, compositions, and aerosol overall shapes. The soot particle configurations and heterogeneities can have a substantial effect that can result in a significant enhancement of extinction and absorption relative to those computed from the Lorenz-Mie theory. Meanwhile the model calculated information combined with in-situ and remote sensed data can be used to constrain soot particle shapes and sizes which are much needed in climate models.

  14. First in-flight synchrotron X-ray absorption and photoemission study of carbon soot nanoparticles

    PubMed Central

    Ouf, F.-X.; Parent, P.; Laffon, C.; Marhaba, I.; Ferry, D.; Marcillaud, B.; Antonsson, E.; Benkoula, S.; Liu, X.-J.; Nicolas, C.; Robert, E.; Patanen, M.; Barreda, F.-A.; Sublemontier, O.; Coppalle, A.; Yon, J.; Miserque, F.; Mostefaoui, T.; Regier, T. Z.; Mitchell, J.-B. A.; Miron, C.

    2016-01-01

    Many studies have been conducted on the environmental impacts of combustion generated aerosols. Due to their complex composition and morphology, their chemical reactivity is not well understood and new developments of analysis methods are needed. We report the first demonstration of in-flight X-ray based characterizations of freshly emitted soot particles, which is of paramount importance for understanding the role of one of the main anthropogenic particulate contributors to global climate change. Soot particles, produced by a burner for several air-to-fuel ratios, were injected through an aerodynamic lens, focusing them to a region where they interacted with synchrotron radiation. X-ray photoelectron spectroscopy and carbon K-edge near-edge X-ray absorption spectroscopy were performed and compared to those obtained for supported samples. A good agreement is found between these samples, although slight oxidation is observed for supported samples. Our experiments demonstrate that NEXAFS characterization of supported samples provides relevant information on soot composition, with limited effects of contamination or ageing under ambient storage conditions. The highly surface sensitive XPS experiments of airborne soot indicate that the oxidation is different at the surface as compared to the bulk probed by NEXAFS. We also report changes in soot’s work function obtained at different combustion conditions. PMID:27883014

  15. Laminar soot processes

    NASA Technical Reports Server (NTRS)

    Sunderland, P. B.; Lin, K.-C.; Faeth, G. M.

    1995-01-01

    Soot processes within hydrocarbon fueled flames are important because they affect the durability and performance of propulsion systems, the hazards of unwanted fires, the pollutant and particulate emissions from combustion processes, and the potential for developing computational combustion. Motivated by these observations, the present investigation is studying soot processes in laminar diffusion and premixed flames in order to better understand the soot and thermal radiation emissions of luminous flames. Laminar flames are being studied due to their experimental and computational tractability, noting the relevance of such results to practical turbulent flames through the laminar flamelet concept. Weakly-buoyant and nonbuoyant laminar diffusion flames are being considered because buoyancy affects soot processes in flames while most practical flames involve negligible effects of buoyancy. Thus, low-pressure weakly-buoyant flames are being observed during ground-based experiments while near atmospheric pressure nonbuoyant flames will be observed during space flight experiments at microgravity. Finally, premixed laminar flames also are being considered in order to observe some aspects of soot formation for simpler flame conditions than diffusion flames. The main emphasis of current work has been on measurements of soot nucleation and growth in laminar diffusion and premixed flames.

  16. An Investigation into the Effect of Hydrodynamic Cavitation on Diesel using Optical Extinction

    NASA Astrophysics Data System (ADS)

    Lockett, R. D.; Fatmi, Z.; Kuti, O.; Price, R.

    2015-12-01

    A conventional diesel and paraffinic-rich model diesel fuel were subjected to sustained cavitation in a custom-built high-pressure recirculation flow rig. Changes to the spectral extinction coefficient at 405 nm were measured using a simple optical arrangement. The spectral extinction coefficient at 405 nm for the conventional diesel sample was observed to increase to a maximum value and then asymptotically decrease to a steady-state value, while that for the paraffinic-rich model diesel was observed to progressively decrease. It is suggested that this is caused by the sonochemical pyrolysis of mono-aromatics to form primary soot-like carbonaceous particles, which then coagulate to form larger particles, which are then trapped by the filter, leading to a steady-state spectral absorbance.

  17. Chemical Characterization and Toxicologic Evaluation of Airborne Mixtures. Tumorigenicity Studies of Diesel Fuel-2, Red Smoke Dye and Violet Smoke Dyes in the SENCAR Mouse Skin Tumorigenesis Bioassay System

    DTIC Science & Technology

    1985-09-01

    11, 4. TITLE (and Subtitle) Chemical Characterization and Toxi - S. TYPE OF REPORT & PERIOD COVERED cologic Evaluation of Airborne Mixtures / Technical...REFERENCES (Cont’d) Nesnow, S., L. L. Triplett, and T. J. Slaga. 1981. Tumorigenesis of diesel exhaust, gasoline exhaust, and related emission

  18. Shock tube studies of thermal radiation of diesel-spray combustion under a range of spray conditions

    NASA Astrophysics Data System (ADS)

    Tsuboi, T.; Kurihara, Y.; Takasaki, M.; Katoh, R.; Ishii, K.

    2007-05-01

    A tailored interface shock tube and an over-tailored interface shock tube were used to measure the thermal energy radiated during diesel-spray combustion of light oil, α-methylnaphthalene and cetane by changing the injection pressure. The ignition delay of methanol and the thermal radiation were also measured. Experiments were performed in a steel shock tube with a 7 m low-pressure section filled with air and a 6 m high-pressure section. Pre-compressed fuel was injected through a throttle nozzle into air behind a reflected shock wave. Monochromatic emissive power and the power emitted across all infrared wavelengths were measured with IR-detectors set along the central axis of the tube. Time-dependent radii where soot particles radiated were also determined, and the results were as follows. For diesel spray combustion with high injection pressures (from 10 to 80 MPa), the thermal radiation energy of light oil per injection increased with injection pressure from 10 to 30 MPa. The energy was about 2% of the heat of combustion of light oil at P inj = about 30 MPa. At injection pressure above 30 MPa the thermal radiation decreased with increasing injection pressure. This profile agreed well with the combustion duration, the flame length, the maximum amount of soot in the flame, the time-integrated soot volume and the time-integrated flame volume. The ignition delay of light oil was observed to decrease monotonically with increasing fuel injection pressure. For diesel spray combustion of methanol, the thermal radiation including that due to the gas phase was 1% of the combustion heat at maximum, and usually lower than 1%. The thermal radiation due to soot was lower than 0.05% of the combustion heat. The ignition delays were larger (about 50%) than those of light oil. However, these differences were within experimental error.

  19. Spectral radiance measurements and calculated soot concentrations along the length of an experimental combustor

    NASA Technical Reports Server (NTRS)

    Norgren, C. T.; Ingebo, R. D.

    1976-01-01

    Radiometric data were obtained over a range of parametric test conditions at three positions along the length of an experimental combustor segment corresponding to the primary, intermediate, and dilution zones. The concentration of soot entrained in the combustion gases was calculated by a technique using spectral radiance measurements. Tests were conducted primarily with Jet A fuel, although limited data were taken with two fuels having higher aromatic content, diesel oil number 2 and a blend of 40 percent tetralin in Jet A fuel. Radiometric observation of the combustion gases indicated that the maximum total radiance peaked at the intermediate zone, which was located immediately upstream of the dilution holes. Soot concentrations calculated from optical measurements in the dilution zone compared favorably with those obtained by in situ gas sampling at the exhaust. The total radiance increased with the higher aromatic content fuels.

  20. Cerium Levels in Fine and Coarse Airborne Particulate Matter in El Paso, Texas—A Geospatial and Temporal Investigation

    NASA Astrophysics Data System (ADS)

    Amaya, M. A.; Ziwu, E.; Clague, J. W.; Pingitore, N. E., Jr.

    2016-12-01

    Known for use as mischmetal in metallurgical processing and as an industrial polishing vehicle, cerium dioxide (CeO2) or ceria is increasingly important in the global nanotechnology sector as a catalyst and diesel fuel additive. Investigations of the release, fate, and environmental and human health effects of CeO2 nanoparticles released into the air are particularly evident in Europe, where nano-ceria is used as a mileage extender and soot particle emission inhibitor in diesel fuel. Here we present an extensive (>2500 samples) data set of Ce analyses in air samples collected over 1-week continuous periods at 8 sites in El Paso, TX, USA at various times during the years 2006-2009. Nano-ceria was not approved for on-road vehicle use during this time frame, so these data establish a local baseline for potential diesel-associated emissions should approval be granted for nano-ceria use in the future. Dichotomous collectors provided simultaneous separate samples of the PMfine (<2.5 µm) and PMcoarse(2.5 - 10 µm) fractions. For all sites, more Ce was measured (by XRF) in the PMcoarse than in the PMfine, with typical Ce concentrations of 2 ng m-3 for the coarse and 1 ng m-3 for the fine. Following the general observation that coarse PM is of geologic origin and fine is anthropogenic, it appears that the majority of atmospheric Ce in El Paso is of natural origin. Further supporting this view, there was no consistent trend for higher airborne Ce values at sampling stations in the urban core, where vehicular or industrial releases would be greater relative to more rural sites. No seasonal trend was obvious in the multi-year data set, as might be expected for anthropogenic releases trapped by winter inversions. Note, however, that the dry desert and windy conditions in El Paso produce unusually high levels of ambient coarse PM. Although we have not yet identified the compounds of airborne Ce, our findings indirectly suggest that anthropogenic nano-ceria is not the dominant

  1. The combustion behavior of diesel/CNG mixtures in a constant volume combustion chamber

    NASA Astrophysics Data System (ADS)

    Firmansyah; Aziz, A. R. A.; Heikal, M. R.

    2015-12-01

    The stringent emissions and needs to increase fuel efficiency makes controlled auto-ignition (CAI) based combustion an attractive alternative for the new combustion system. However, the combustion control is the main obstacles in its development. Reactivity controlled compression ignition (RCCI) that employs two fuels with significantly different in reactivity proven to be able to control the combustion. The RCCI concept applied in a constant volume chamber fuelled with direct injected diesel and compressed natural gas (CNG) was tested. The mixture composition is varied from 0 - 100% diesel/CNG at lambda 1 with main data collection are pressure profile and combustion images. The results show that diesel-CNG mixture significantly shows better combustion compared to diesel only. It is found that CNG is delaying the diesel combustion and at the same time assisting in diesel distribution inside the chamber. This combination creates a multipoint ignition of diesel throughout the chamber that generate very fast heat release rate and higher maximum pressure. Furthermore, lighter yellow color of the flame indicates lower soot production in compared with diesel combustion.

  2. Computational modeling of soot nucleation

    NASA Astrophysics Data System (ADS)

    Chung, Seung-Hyun

    Recent studies indicate that soot is the second most significant driver of climate change---behind CO2, but ahead of methane---and increased levels of soot particles in the air are linked to health hazards such as heart disease and lung cancer. Within the soot formation process, soot nucleation is the least understood step, and current experimental findings are still limited. This thesis presents computational modeling studies of the major pathways of the soot nucleation process. In this study, two regimes of soot nucleation---chemical growth and physical agglomeration---were evaluated and the results demonstrated that combustion conditions determine the relative importance of these two routes. Also, the dimerization process of polycyclic aromatic hydrocarbons, which has been regarded as one of the most important physical agglomeration processes in soot formation, was carefully examined with a new method for obtaining the nucleation rate using molecular dynamics simulation. The results indicate that the role of pyrene dimerization, which is the commonly accepted model, is expected to be highly dependent on various flame temperature conditions and may not be a key step in the soot nucleation process. An additional pathway, coronene dimerization in this case, needed to be included to improve the match with experimental data. The results of this thesis provide insight on the soot nucleation process and can be utilized to improve current soot formation models.

  3. Diesel reformulation using bio-derived propanol to control toxic emissions from a light-duty agricultural diesel engine.

    PubMed

    Thillainayagam, Muthukkumar; Venkatesan, Krishnamoorthy; Dipak, Rana; Subramani, Saravanan; Sethuramasamyraja, Balaji; Babu, Rajesh Kumar

    2017-07-01

    In the Indian agricultural sector, millions of diesel-driven pump-sets were used for irrigation purposes. These engines produce carcinogenic diesel particulates, toxic nitrogen oxides (NOx), and carbon monoxide (CO) emissions which threaten the livelihood of large population of farmers in India. The present study investigates the use of n-propanol, a less-explored high carbon bio-alcohol that can be produced by sustainable pathways from industrial and crop wastes that has an attractive opportunity for powering stationary diesel engines meant for irrigation and rural electrification. This study evaluates the use of n-propanol addition in fossil diesel by up to 30% by vol. and concurrently reports the effects of exhaust gas recirculation (EGR) on emissions of an agricultural DI diesel engine. Three blends PR10, PR20, and PR30 were prepared by mixing 10, 20, and 30% by vol. of n-propanol with fossil diesel. Results when compared to baseline diesel case indicated that smoke density reduced with increasing n-propanol fraction in the blends. PR10, PR20, and PR30 reduced smoke density by 13.33, 33.33, and 60%, respectively. NOx emissions increased with increasing n-propanol fraction in the blends. Later, three EGR rates (10, 20, and 30%) were employed. At any particular EGR rate, smoke density remained lower with increasing n-propanol content in the blends under increasing EGR rates. NOx reduced gradually with EGR. At 30% EGR, the blends PR10, PR20, and PR30 reduced NOx emissions by 43.04, 37.98, and 34.86%, respectively when compared to baseline diesel. CO emissions remained low but hydrocarbon (HC) emissions were high for n-propanol/diesel blends under EGR. Study confirmed that n-propanol could be used by up to 30% by vol. with diesel and the blends delivered lower soot density, NOx, and CO emissions under EGR.

  4. Physicochemical and toxicological characteristics of particulate matter emitted from a non-road diesel engine: comparative evaluation of biodiesel-diesel and butanol-diesel blends.

    PubMed

    Zhang, Zhi-Hui; Balasubramanian, Rajasekhar

    2014-01-15

    Combustion experiments were conducted to evaluate the effects of using blends of ultralow sulfur diesel (ULSD) with biodiesel or n-butanol on physicochemical and toxicological characteristics of particulate emissions from a non-road diesel engine. The results indicated that compared to ULSD, both the blended fuels could effectively reduce the particulate mass and elemental carbon emissions, with butanol being more effective than biodiesel. The proportion of organic carbon and volatile organic compounds in particles increased for both blended fuels. However, biodiesel blended fuels showed lower total particle-phase polycyclic aromatic hydrocarbons (PAHs) emissions. The total number emissions of particles ≤560nm in diameter decreased gradually for the butanol blended fuels, but increased significantly for the biodiesel blended fuels. Both the blended fuels indicated lower soot ignition temperature and activation energy. All the particle extracts showed a decline in cell viability with the increased dose. However, the change in cell viability among test fuels is not statistically significant different with the exception of DB-4 (biodiesel-diesel blend containing 4% oxygen) used at 75% engine load. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. Effect of fuel injection pressure on a heavy-duty diesel engine nonvolatile particle emission.

    PubMed

    Lähde, Tero; Rönkkö, Topi; Happonen, Matti; Söderström, Christer; Virtanen, Annele; Solla, Anu; Kytö, Matti; Rothe, Dieter; Keskinen, Jorma

    2011-03-15

    The effects of the fuel injection pressure on a heavy-duty diesel engine exhaust particle emissions were studied. Nonvolatile particle size distributions and gaseous emissions were measured at steady-state engine conditions while the fuel injection pressure was changed. An increase in the injection pressure resulted in an increase in the nonvolatile nucleation mode (core) emission at medium and at high loads. At low loads, the core was not detected. Simultaneously, a decrease in soot mode number concentration and size and an increase in the soot mode distribution width were detected at all loads. Interestingly, the emission of the core was independent of the soot mode concentration at load conditions below 50%. Depending on engine load conditions, growth of the geometric mean diameter of the core mode was also detected with increasing injection pressure. The core mode emission and also the size of the mode increased with increasing NOx emission while the soot mode size and emission decreased simultaneously.

  6. Laminar Soot Processes (LSP)

    NASA Technical Reports Server (NTRS)

    Dai, Z.; El-Leathy, A. M.; Kim, C. H.; Krishnan, S. S.; Lin, K.-C.; Xu, F.; Faeth, G. M.

    2002-01-01

    This is the final report of a research program considering the structure and the soot surface reaction properties of laminar nonpremixed (diffusion) flames. The study was limited to ground-based measurements of buoyant laminar jet diffusion flames at pressures of 0.1-1.0 atm. The motivation for the research is that soot formation in flames is a major unresolved problem of combustion science that influences the pollutant emissions, durability and performance of power and propulsion systems, as well as the potential for developing computational combustion. The investigation was divided into two phases considering the structure of laminar soot-containing diffusion flames and the soot surface reaction properties (soot surface growth and oxidation) of these flames, in turn. The first phase of the research addressed flame and soot structure properties of buoyant laminar jet diffusion flames at various pressures. The measurements showed that H, OH and O radical concentrations were generally in superequilibrium concentrations at atmospheric pressure but tended toward subequilibrium concentrations as pressures decreased. The measurements indicated that the original fuel decomposed into more robust compounds at elevated temperatures, such as acetylene (unless the original fuel was acetylene) and H, which are the major reactants for soot surface growth, and that the main effect of the parent fuel on soot surface growth involved its yield of acetylene and H for present test conditions. The second phase of the research addressed soot surface reaction properties, e.g., soot surface growth and surface oxidation. It was found that soot surface growth rates in both laminar premixed and diffusion flames were in good agreement, that these rates were relatively independent of fuel type, and that these rates could be correlated by the Hydrogen-Abstraction/Carbon-Addition (HACA) mechanisms of Colket and Hall (1994), Frenklach et al. (1990,1994), and Kazakov et al. (1995). It was also

  7. Fractal and spectroscopic analysis of soot from internal combustion engines

    NASA Astrophysics Data System (ADS)

    Swapna, M. S.; Saritha Devi, H. V.; Raj, Vimal; Sankararaman, S.

    2018-03-01

    Today diesel engines are used worldwide for various applications and very importantly in transportation. Hydrocarbons are the most widespread precursors among carbon sources employed in the production of carbon nanotubes (CNTs). The aging of internal combustion engine is an important parameter in deciding the carbon emission and particulate matter due to incomplete combustion of fuel. In the present work, an attempt has been made for the effective utilization of the aged engines for potential applicationapplications in fuel cells and nanoelectronics. To analyze the impact of aging, the particulate matter rich in carbon content areis collected from diesel engines of different ages. The soot with CNTs is purified by the liquid phase oxidation method and analyzed by Field Emission Scanning Electron Microscopy, High-Resolution Transmission Electron Microscopy, Energy Dispersive Spectroscopy, UV-Visible spectroscopy, Raman spectroscopy and Thermogravimetric analysis. The SEM image contains self-similar patterns probing fractal analysis. The fractal dimensions of the samples are determined by the box counting method. We could find a greater amount of single-walled carbon nanotubes (SWCNTs) in the particulate matter emitted by aged diesel engines and thereby giving information about the combustion efficiency of the engine. The SWCNT rich sample finds a wide range of applicationapplications in nanoelectronics and thereby pointing a potential use of these aged engines.

  8. Modeling the effects of auxiliary gas injection and fuel injection rate shape on diesel engine combustion and emissions

    NASA Astrophysics Data System (ADS)

    Mather, Daniel Kelly

    1998-11-01

    The effect of auxiliary gas injection and fuel injection rate-shaping on diesel engine combustion and emissions was studied using KIVA a multidimensional computational fluid dynamics code. Auxiliary gas injection (AGI) is the injection of a gas, in addition to the fuel injection, directly into the combustion chamber of a diesel engine. The objective of AGI is to influence the diesel combustion via mixing to reduce emissions of pollutants (soot and NO x). In this study, the accuracy of modeling high speed gas jets on very coarse computational grids was addressed. KIVA was found to inaccurately resolve the jet flows near walls. The cause of this inaccuracy was traced to the RNG k - ɛ turbulence model with the law-of-the-wall boundary condition used by KIVA. By prescribing the lengthscale near the nozzle exit, excellent agreement between computed and theoretical jet penetration was attained for a transient gas jet into a quiescent chamber at various operating conditions. The effect of AGI on diesel engine combustion and emissions was studied by incorporating the coarse grid gas jet model into a detailed multidimensional simulation of a Caterpillar 3401 heavy-duty diesel engine. The effects of AGI timing, composition, amount, orientation, and location were investigated. The effects of AGI and split fuel injection were also investigated. AGI was found to be effective at reducing soot emissions by increasing mixing within the combustion chamber. AGI of inert gas was found to be effective at reducing emissions of NOx by depressing the peak combustion temperatures. Finally, comparison of AGI simulations with experiments were conducted for a TACOM-LABECO engine. The results showed that AGI improved soot oxidation throughout the engine cycle. Simulation of fuel injection rate-shaping investigated the effects of three injection velocity profiles typical of unit-injector type, high-pressure common-rail type, and accumulator-type fuel injectors in the Caterpillar 3401 heavy

  9. Development of a reduced tri-propylene glycol monomethyl ether– n -hexadecane–poly-aromatic hydrocarbon mechanism and its application for soot prediction

    DOE PAGES

    Park, Seunghyun; Ra, Youngchul; Reitz, Rolf D.; ...

    2016-03-01

    A reduced chemical kinetic mechanism for Tri-Propylene Glycol Monomethyl Ether (TPGME) has been developed and applied to computational fluid dynamics (CFD) calculations for predicting combustion and soot formation processes. The reduced TPGME mechanism was combined with a reduced n-hexadecane mechanism and a Poly-Aromatic Hydrocarbon (PAH) mechanism to investigate the effect of fuel oxygenation on combustion and soot emissions. The final version of the TPGME-n-hexadecane-PAH mechanism consists of 144 species and 730 reactions and was validated with experiments in shock tubes as well as in a constant volume spray combustion vessel (CVCV) from the Engine Combustion Network (ECN). The effects ofmore » ambient temperature, varying oxygen content in the tested fuels on ignition delay, spray liftoff length and soot formation under diesel-like conditions were analyzed and addressed using multidimensional reacting flow simulations and the reduced mechanism. Here, the results show that the present reduced mechanism gives reliable predictions of the combustion characteristics and soot formation processes. In the CVCV simulations, two important trends were identified. First, increasing the initial temperature in the CVCV shortens the ignition delay and lift-off length, reduces the fuel-air mixing, thereby increasing the soot levels. Secondly, fuel oxygenation introduces more oxygen into the central region of a fuel jet and reduces residence times of fuel rich area in active soot forming regions, thereby reducing soot levels.« less

  10. Development of a reduced tri-propylene glycol monomethyl ether– n -hexadecane–poly-aromatic hydrocarbon mechanism and its application for soot prediction

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Park, Seunghyun; Ra, Youngchul; Reitz, Rolf D.

    A reduced chemical kinetic mechanism for Tri-Propylene Glycol Monomethyl Ether (TPGME) has been developed and applied to computational fluid dynamics (CFD) calculations for predicting combustion and soot formation processes. The reduced TPGME mechanism was combined with a reduced n-hexadecane mechanism and a Poly-Aromatic Hydrocarbon (PAH) mechanism to investigate the effect of fuel oxygenation on combustion and soot emissions. The final version of the TPGME-n-hexadecane-PAH mechanism consists of 144 species and 730 reactions and was validated with experiments in shock tubes as well as in a constant volume spray combustion vessel (CVCV) from the Engine Combustion Network (ECN). The effects ofmore » ambient temperature, varying oxygen content in the tested fuels on ignition delay, spray liftoff length and soot formation under diesel-like conditions were analyzed and addressed using multidimensional reacting flow simulations and the reduced mechanism. Here, the results show that the present reduced mechanism gives reliable predictions of the combustion characteristics and soot formation processes. In the CVCV simulations, two important trends were identified. First, increasing the initial temperature in the CVCV shortens the ignition delay and lift-off length, reduces the fuel-air mixing, thereby increasing the soot levels. Secondly, fuel oxygenation introduces more oxygen into the central region of a fuel jet and reduces residence times of fuel rich area in active soot forming regions, thereby reducing soot levels.« less

  11. Mutagenicity of diesel exhaust particles and oil shale particles dispersed in lecithin surfactant.

    PubMed

    Wallace, W E; Keane, M J; Hill, C A; Xu, J; Ong, T M

    1987-01-01

    Diesel exhaust particulate material from exhaust pipe scrapings of two trucks, diluted automobile diesel exhaust particulate material collected on filters, and two oil shale ores were prepared for the Ames mutagenicity assay by dichloromethane (DCM) extraction, by dispersion into 0.85% saline, or by dispersion into dipalmitoyl lecithin (DPL) emulsion in saline. Salmonella typhimurium TA98 was used to detect frameshift mutagens in the samples. Samples of diesel soot gave positive mutagenic responses with both DCM extraction and DPL dispersion, with the DPL dispersion giving higher results in some cases. The results suggest that possible mutagens associated with inhaled particles may be dispersed or solubilized into the phospholipid component of pulmonary surfactant and become active in such a phase.

  12. Effects of Soot Structure on Soot Oxidation Kinetics

    DTIC Science & Technology

    2011-06-01

    information from PSDs, temperature, gas -phase composition was used to develop an oxidation kinetic expression that accounts for the effects of...from PSDs, temperature, gas -phase composition was used to develop an oxidation kinetic expression that accounts for the effects of temperature, O2, and...systematic studies of these effects under the temperatures and times of interest to soot oxidation in gas turbine engines. Studies have shown that soot

  13. Simultaneous NOx and Particulate Matter Removal from Diesel Exhaust by Hierarchical Fe-Doped Ce–Zr Oxide

    PubMed Central

    2017-01-01

    Particulate matter and NOx emissions from diesel exhaust remains one of the most pressing environmental problems. We explore the use of hierarchically ordered mixed Fe–Ce–Zr oxides for the simultaneous capture and oxidation of soot and reduction of NOx by ammonia in a single step. The optimized material can effectively trap the model soot particles in its open macroporous structure and oxidize the soot below 400 °C while completely removing NO in the 285–420 °C range. Surface characterization and DFT calculations emphasize the defective nature of Fe-doped ceria. The isolated Fe ions and associated oxygen vacancies catalyze facile NO reduction to N2. A mechanism for the reduction of NO with NH3 on Fe-doped ceria is proposed involving adsorbed O2. Such adsorbed O2 species will also contribute to the oxidation of soot. PMID:28603656

  14. Persistent free radicals, heavy metals and PAHs generated in particulate soot emissions and residue ash from controlled combustion of common types of plastic.

    PubMed

    Valavanidis, Athanasios; Iliopoulos, Nikiforos; Gotsis, George; Fiotakis, Konstantinos

    2008-08-15

    The production and use of polymeric materials worldwide has reached levels of 150 million tonnes per year, and the majority of plastic materials are discarded in waste landfills where are burned generating toxic emissions. In the present study we conducted laboratory experiments for batch combustion/burning of commercial polymeric materials, simulating conditions of open fire combustion, with the purpose to analyze their emissions for chemical characteristics of toxicological importance. We used common types of plastic materials: poly(vinyl chloride) (PVC), low and high density poly(ethylene) (LDPE, HDPE), poly(styrene) (PS), poly(propylene) (PP) and poly(ethylene terephthalate) (PET). Samples of particulate smoke (soot) collected on filters and residue solid ash produced by controlled burning conditions at 600-750 degrees C are used for analysis. Emissions of particulate matter, persistent free radicals embedded in the carbonaceous polymeric matrix, heavy metals, other elements and PAHs were determined in both types of samples. Results showed that all plastics burned easily generating charred residue solid ash and black airborne particulate smoke. Persistent carbon- and oxygen-centered radicals, known for their toxic effects in inhalable airborne particles, were detected in both particulate smoke emissions and residue solid ash. Concentrations of heavy metals and other elements (determined by Inductively Coupled Plasma Emission Spectrometry, ICP, method) were measured in the airborne soot and residue ash. Toxic heavy metals, such as Pb, Zn, Cr, Ni, and Cd were relatively at were found at low concentrations. High concentrations were found for some lithophilic elements, such as Na, Ca, Mg, Si and Al in particulate soot and residue solid ash. Measurements of PAHs showed that low molecular weight PAHs were at higher concentrations in the airborne particulate soot than in the residue solid ash for all types of plastic. Higher-ringed PAHs were detected at higher

  15. Experimental investigation on the morphology of soot aggregates from the burning of typical solid and liquid fuels

    NASA Astrophysics Data System (ADS)

    Huang, Dongmei; Guo, Chenning; Shi, Long

    2017-03-01

    Soot particles from the burning of typical fuels are one of the critical sources causing environmental problems and human disease. To understand the soot formation of these typical fuels, the size and morphology of soot aggregates produced from the burning of typical solid and liquid fuels, including diesel, kerosene, natural rubber (NR) latex foam, and wood crib, were studied by both extractive sampling and subsequent image analysis. The 2D and 3D fractal dimensions together with the diameter distribution of agglomerate and primary particles were analyzed for these four typical fuels. The average diameters of the primary particles were within 45-85 nm when sampling from different heights above the fire sources. Irregular sheet structures and flake-like masses were observed from the burning of NR latex foam and wood cribs. Superaggregates with a mean maximum length scale of over 100 μm were also found from the burning of all these four tested fuels. The fractal dimension of a single aggregate was 3 for all the tested fuels.

  16. T-matrix modeling of linear depolarization by morphologically complex soot and soot-containing aerosols

    NASA Astrophysics Data System (ADS)

    Mishchenko, Michael I.; Liu, Li; Mackowski, Daniel W.

    2013-07-01

    We use state-of-the-art public-domain Fortran codes based on the T-matrix method to calculate orientation and ensemble averaged scattering matrix elements for a variety of morphologically complex black carbon (BC) and BC-containing aerosol particles, with a special emphasis on the linear depolarization ratio (LDR). We explain theoretically the quasi-Rayleigh LDR peak at side-scattering angles typical of low-density soot fractals and conclude that the measurement of this feature enables one to evaluate the compactness state of BC clusters and trace the evolution of low-density fluffy fractals into densely packed aggregates. We show that small backscattering LDRs measured with ground-based, airborne, and spaceborne lidars for fresh smoke generally agree with the values predicted theoretically for fluffy BC fractals and densely packed near-spheroidal BC aggregates. To reproduce higher lidar LDRs observed for aged smoke, one needs alternative particle models such as shape mixtures of BC spheroids or cylinders.

  17. T-Matrix Modeling of Linear Depolarization by Morphologically Complex Soot and Soot-Containing Aerosols

    NASA Technical Reports Server (NTRS)

    Mishchenko, Michael I.; Liu, Li; Mackowski, Daniel W.

    2013-01-01

    We use state-of-the-art public-domain Fortran codes based on the T-matrix method to calculate orientation and ensemble averaged scattering matrix elements for a variety of morphologically complex black carbon (BC) and BC-containing aerosol particles, with a special emphasis on the linear depolarization ratio (LDR). We explain theoretically the quasi-Rayleigh LDR peak at side-scattering angles typical of low-density soot fractals and conclude that the measurement of this feature enables one to evaluate the compactness state of BC clusters and trace the evolution of low-density fluffy fractals into densely packed aggregates. We show that small backscattering LDRs measured with groundbased, airborne, and spaceborne lidars for fresh smoke generally agree with the values predicted theoretically for fluffy BC fractals and densely packed near-spheroidal BC aggregates. To reproduce higher lidar LDRs observed for aged smoke, one needs alternative particle models such as shape mixtures of BC spheroids or cylinders.

  18. Laminar Soot Processes

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Image of soot (smoke) plume made for the Laminar Soot Processes (LSP) experiment during the Microgravity Sciences Lab-1 mission in 1997. LSP-2 will fly in the STS-107 Research 1 mission in 2002. The principal investigator is Dr. Gerard Faeth of the University of Michigan. LSP uses a small jet burner, similar to a classroom butane lighter, that produces flames up to 60 mm (2.3 in) long. Measurements include color TV cameras and a temperature sensor, and laser images whose darkness indicates the quantity of soot produced in the flame. Glenn Research in Cleveland, OH, manages the project.

  19. Performance, emission, and combustion characteristics of twin-cylinder common rail diesel engine fuelled with butanol-diesel blends.

    PubMed

    Lamani, Venkatesh Tavareppa; Yadav, Ajay Kumar; Gottekere, Kumar Narayanappa

    2017-10-01

    Nitrogen oxides and smoke are the substantial emissions for the diesel engines. Fuels comprising high-level oxygen content can have low smoke emission due to better oxidation of soot. The objective of the paper is to assess the potential to employ oxygenated fuel, i.e., n-butanol and its blends with the neat diesel from 0 to 30% by volume. The experimental and computational fluid dynamic (CFD) simulation is carried out to estimate the performance, combustion, and exhaust emission characteristics of n-butanol-diesel blends for various injection timings (9°, 12°, 15°, and 18°) using modern twin-cylinder, four-stroke, common rail direct injection (CRDI) engine. Experimental results reveal the increase in brake thermal efficiency (BTE) by ~ 4.5, 6, and 8% for butanol-diesel blends of 10% (Bu10), 20% (Bu20), and 30% (Bu30), respectively, compared to neat diesel (Bu0). Maximum BTE for Bu0 is 38.4%, which is obtained at 12° BTDC; however, for Bu10, Bu20 and Bu30 are 40.19, 40.9, and 41.7%, which are obtained at 15° BTDC, respectively. Higher flame speed of n-butanol-diesel blends burn a large amount of fuel in the premixed phase, which improves the combustion as well as emission characteristics. CFD and experimental results are compared and validated for all fuel blends for in-cylinder pressure and nitrogen oxides (NO x ), and found to be in good agreement. Both experimental and simulation results witnessed in reduction of smoke opacity, NO x , and carbon monoxide emissions with the increasing n-butanol percentage in diesel fuel.

  20. Precursor soot synthesis of fullerenes and nanotubes without formation of carbonaceous soot

    DOEpatents

    Reilly, Peter T. A.

    2007-03-20

    The present invention is a method for the synthesis of fullerenes and/or nanotubes from precursor soot without the formation of carbonaceous soot. The method comprises the pyrolysis of a hydrocarbon fuel source by heating the fuel source at a sufficient temperature to transform the fuel source to a condensed hydrocarbon. The condensed hydrocarbon is a reaction medium comprising precursor soot wherein hydrogen exchange occurs within the reaction medium to form reactive radicals which cause continuous rearrangement of the carbon skeletal structure of the condensed hydrocarbon. Then, inducing dehydrogenation of the precursor soot to form fullerenes and/or nanotubes free from the formation of carbonaceous soot by continued heating at the sufficient temperature and by regulating the carbon to hydrogen ratio within the reaction medium. The dehydrogenation process produces hydrogen gas as a by-product. The method of the present invention in another embodiment is also a continuous synthesis process having a continuous supply of the fuel source. The method of the present invention can also be a continuous cyclic synthesis process wherein the reaction medium is fed back into the system as a fuel source after extraction of the fullerenes and/or nanotube products. The method of the present invention is also a method for producing precursor soot in bulk quantity, then forming fullerenes and/or nanotubes from the precursor bulk.

  1. Ice Nucleation of Soot Particles in the Cirrus Regime: Is Pore Condensation and Freezing Relevant for Soot?

    NASA Astrophysics Data System (ADS)

    Kanji, Z. A.; Mahrt, F.; David, R.; Marcolli, C.; Lohmann, U.; Fahrni, J.; Brühwiler, D.

    2017-12-01

    Heterogeneous ice nucleation (HIN) onto soot particles from previous studies have produced inconsistent results of temperature and relative humidity conditions required for freezing depending on the source of soot particle investigated. The ability of soot to act as HIN depended on the type of soot and size of particle. Often homogenous freezing conditions or water saturation conditions were required to freeze soot particles, rendering HIN irrelevant. Using synthesised mesoporous silica particles, we show pore condensation and freezing works with experiments performed in the Zurich Ice Nucleation Chamber (ZINC). By testing a variety of soot particles in parallel in the Horizontal Ice Nucleation Chamber (HINC), we suggest that previously observed HIN on soot particles is not the responsible mechanism for ice formation. Laboratory generated CAST brown and black soot, commercially available soot and acid treated soot were investigated for their ice nucleation abilities in the mixed-phase and cirrus cloud temperature regimes. No heterogeneous ice nucleation activity is inferred at T > -38 °C (mixed-phase cloud regime), however depending on particle size and soot type, HIN was observed for T < -38 °C (cirrus could regime). Nevertheless, we question if this is caused by a heterogeneous phase change due the presence of a so called active site or due to pore-condensation of water as predicted by the inverse Kelvin effect followed by homogeneous nucleation of ice in the pores or cavities that are ubiquitous in soot particles between the primary spherules. The ability of some particles to freeze at lower relative humidity compared to others demonstrates why hydrophobicity plays a role in ice nucleation, i.e. controlling the conditions at which these cavities fill with water. Thus for more hydrophobic particles pore filling occurs at higher relative humidity, and therefore freezing of pore water and ice crystal growth. Future work focusses on testing the cloud processing

  2. Nitro-PAH formation studied by interacting artificially PAH-coated soot aerosol with NO 2 in the temperature range of 295-523 K

    NASA Astrophysics Data System (ADS)

    Carrara, Matteo; Wolf, Jan-Christoph; Niessner, Reinhard

    2010-10-01

    Diesel particulate matter poses a threat to human health, and in particular nitrated polycyclic aromatic hydrocarbons (NPAHs) found within and on the surface of these particles. Although diesel particulate filters (DPFs) have been designed and implemented to reduce these and other harmful diesel emissions, the particle loaded filters may act as a reaction chamber for the enhanced production of NPAHs from the nitration of PAHs with NO 2. Focus is on the investigation of the heterogeneous reactions that occur on soot particles by exposing laboratory produced pyrene- or benzo(a)pyrene-coated spark discharge soot particles to varying concentrations of NO 2 and temperatures while following the formation of products over time. The sole nitration product that was observed throughout the experiments with pyrene-coated soot was 1-nitropyrene (1-NPYR), which increased linearly with reaction time for all NO 2 concentrations chosen (0.11, 1.0, 2.0, 4.0 ppm, m m -1). Resulting 1-NPYR formation rate increased exponentially with [NO 2]. Throughout the 3-h experiments less than 10% of pyrene has been converted to 1-NPYR and the partial reaction order with regard to [NO 2] was estimated to 1.52. Benzo(a)pyrene (BaP) was more reactive than pyrene. After 3 h reaction time almost 80% of the BaP has been converted to 6-NBaP. Highest 1-NPYR concentrations on particles were detected at 373 K, and at higher temperatures a considerable decrease in particulate 1-NPYR was observed. A similar trend was observed in a DPF simulation system (PM-Kat ®-like) with BaP-coated soot. In this case, highest 6-NBaP concentration on particles was detected at 423 K. Backed by corroborating results from separate gas/solid-phase partition experiments with 1-NPYR and 6-NBaP, it is likely that the newly formed 1-NPYR and 6-NBaP became transferred from particle to gas phase at higher temperatures. Results from this study confirm the presence of 1-NPYR and 6-NBaP in particulate and gas phase under conditions

  3. Soot formation and burnout in flames

    NASA Technical Reports Server (NTRS)

    Prado, B.; Bittner, J. D.; Neoh, K.; Howard, J. B.

    1980-01-01

    The amount of soot formed when burning a benzene/hexane mixture in a turbulent combustor was examined. Soot concentration profiles in the same combustor for kerosene fuel are given. The chemistry of the formation of soot precursors, the nucleation, growth and subsequent burnout of soot particles, and the effect of mixing on the previous steps were considered.

  4. Volatile nanoparticle formation and growth within a diluting diesel car exhaust.

    PubMed

    Uhrner, Ulrich; Zallinger, Michael; von Löwis, Sibylle; Vehkamäki, Hanna; Wehner, Birgit; Stratmann, Frank; Wiedensohler, Alfred

    2011-04-01

    A major source of particle number emissions is road traffic. However, scientific knowledge concerning secondary particle formation and growth of ultrafine particles within vehicle exhaust plumes is still very limited. Volatile nanoparticle formation and subsequent growth conditions were analyzed here to gain a better understanding of "real-world" dilution conditions. Coupled computational fluid dynamics and aerosol microphysics models together with measured size distributions within the exhaust plume of a diesel car were used. The impact of soot particles on nucleation, acting as a condensational sink, and the possible role of low-volatile organic components in growth were assessed. A prescribed reduction of soot particle emissions by 2 orders of magnitude (to capture the effect of a diesel particle filter) resulted in concentrations of nucleation-mode particles within the exhaust plume that were approximately 1 order of magnitude larger. Simulations for simplified sulfuric acid-water vapor gas-oil containing nucleation-mode particles show that the largest particle growth is located in a recirculation zone in the wake of the car. Growth of particles within the vehicle exhaust plume up to detectable size depends crucially on the relationship between the mass rate of gaseous precursor emissions and rapid dilution. Chassis dynamometer measurements indicate that emissions of possible hydrocarbon precursors are significantly enhanced under high engine load conditions and high engine speed. On the basis of results obtained for a diesel passenger car, the contributions from light diesel vehicles to the observed abundance of measured nucleation-mode particles near busy roads might be attributable to the impact of two different time scales: (1) a short one within the plume, marked by sufficient precursor emissions and rapid dilution; and (2) a second and comparatively long time scale resulting from the mix of different precursor sources and the impact of atmospheric

  5. Combustion of diesel fuel from a toxicological perspective. I. Origin of incomplete combustion products.

    PubMed

    Scheepers, P T; Bos, R P

    1992-01-01

    Since the use of diesel engines is still increasing, the contribution of their incomplete combustion products to air pollution is becoming ever more important. The presence of irritating and genotoxic substances in both the gas phase and the particulate phase constituents is considered to have significant health implications. The quantity of soot particles and the particle-associated organics emitted from the tail pipe of a diesel-powered vehicle depend primarily on the engine type and combustion conditions but also on fuel properties. The quantity of soot particles in the emissions is determined by the balance between the rate of formation and subsequent oxidation. Organics are absorbed onto carbon cores in the cylinder, in the exhaust system, in the atmosphere and even on the filter during sample collection. Diesel fuel contains polycyclic aromatic hydrocarbons (PAHs) and some alkyl derivatives. Both groups of compounds may survive the combustion process. PAHs are formed by the combustion of crankcase oil or may be resuspended from engine and/or exhaust deposits. The conversion of parent PAHs to oxygenated and nitrated PAHs in the combustion chamber or in the exhaust system is related to the vast amount of excess combustion air that is supplied to the engine and the high combustion temperature. Whether the occurrence of these derivatives is characteristic for the composition of diesel engine exhaust remains to be ascertained. After the emission of the particles, their properties may change because of atmospheric processes such as aging and resuspension. The particle-associated organics may also be subject to (photo)chemical conversions or the components may change during sampling and analysis. Measurement of emissions of incomplete combustion products as determined on a chassis dynamometer provides knowledge of the chemical composition of the particle-associated organics. This knowledge is useful as a basis for a toxicological evaluation of the health hazards of

  6. Monitoring the soot emissions of passing cars.

    PubMed

    Kurniawan, A; Schmidt-Ott, A

    2006-03-15

    We report on the first application of a novel fast on-road sensing method for measurement of particulate emissions of individual passing passenger cars. The studywas motivated by the shift of interest from gases to particles in connection with strong adverse health effects. The results correspond very much to findings by Beaton et al. (Science, May 19,1995) for gaseous hydrocarbon and CO emissions: A small percentage of "superpolluters" (here 5%) account for a high percentage (here 43%) of the pollution (here elemental carbon). We estimate that up to 50% of the particulate emissions of vehicles could be avoided on the basis of the present legislation, if on-road monitoring would be applied to enforce maintenance. Our fast sensing method for particles is based on photoelectron emission from the emitted airborne soot particles in combination with a CO2 sensor delivering a reference.

  7. Response of rodents to inhaled diluted diesel exhaust: biochemical and cytological changes in bronchoalveolar lavage fluid and in lung tissue

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Henderson, R.F.; Pickrell, J.A.; Jones, R.K.

    1988-10-01

    The effect of long-term (24 months) inhalation of diesel exhaust on the bronchoalveolar region of the respiratory tract of rodents was assessed by serial (every 6 months) analysis of bronchoalveolar lavage fluid (BALF) and of lung tissue from F344/Crl rats and CD-1 mice (both sexes) exposed to diesel exhaust diluted to contain 0, 0.35, 3.5, or 7.0 mg soot/m3. The purpose of the study was twofold. One was to assess the potential health effects of inhaling diluted exhaust from light-duty diesel engines. The second was to determine the usefulness of BALF analysis in detecting the early stages in the developmentmore » of nononcogenic lung disease and differentiating them from the normal repair processes. No biochemical or cytological changes in BALF or in lung tissue were noted in either species exposed to the lowest, and most environmentally relevant, concentration of diesel exhaust. In the two higher levels of exposure, a chronic inflammatory response was measured in both species by dose-dependent increases in inflammatory cells, cytoplasmic and lysosomal enzymes, and protein in BALF. Histologically, after 1 year of exposure, the rats had developed focal areas of fibrosis associated with the deposits of soot, while the mice, despite a higher lung burden of soot than the rats, had only a fine fibrillar thickening of an occasional alveolar septa in the high-level exposure group. Higher increases in BALF beta-glucuronidase activity and in hydroxyproline content accompanied the greater degree of fibrosis in the rat. BALF levels of glutathione (GSH) and glutathione reductase activity increased in a dose-dependent fashion and were higher in mice than in rats. Lung tissue GSH was depleted in a dose-dependent fashion in rats but was slightly increased in mice.« less

  8. Primary and Aggregate Size Distributions of PM in Tail Pipe Emissions form Diesel Engines

    NASA Astrophysics Data System (ADS)

    Arai, Masataka; Amagai, Kenji; Nakaji, Takayuki; Hayashi, Shinji

    Particulate matter (PM) emission exhausted from diesel engine should be reduced to keep the clean air environment. PM emission was considered that it consisted of coarse and aggregate particles, and nuclei-mode particles of which diameter was less than 50nm. However the detail characteristics about these particles of the PM were still unknown and they were needed for more physically accurate measurement and more effective reduction of exhaust PM emission. In this study, the size distributions of solid particles in PM emission were reported. PMs in the tail-pipe emission were sampled from three type diesel engines. Sampled PM was chemically treated to separate the solid carbon fraction from other fractions such as soluble organic fraction (SOF). The electron microscopic and optical-manual size measurement procedures were used to determine the size distribution of primary particles those were formed through coagulation process from nuclei-mode particles and consisted in aggregate particles. The centrifugal sedimentation method was applied to measure the Stokes diameter of dry-soot. Aerodynamic diameters of nano and aggregate particles were measured with scanning mobility particle sizer (SMPS). The peak aggregate diameters detected by SMPS were fallen in the same size regime as the Stokes diameter of dry-soot. Both of primary and Stokes diameters of dry-soot decreased with increases of engine speed and excess air ratio. Also, the effects of fuel properties and engine types on primary and aggregate particle diameters were discussed.

  9. Soot Formation in Purely-Curved Premixed Flames and Laminar Flame Speeds of Soot-Forming Flames

    NASA Technical Reports Server (NTRS)

    Buchanan, Thomas; Wang, Hai

    2005-01-01

    The research addressed here is a collaborative project between University of Delaware and Case Western Reserve University. There are two basic and related scientific objectives. First, we wish to demonstrate the suitability of spherical/cylindrical, laminar, premixed flames in the fundamental study of the chemical and physical processes of soot formation. Our reasoning is that the flame standoff distance in spherical/cylindrical flames under microgravity can be substantially larger than that in a flat burner-stabilized flame. Therefore the spherical/cylindrical flame is expected to give better spatial resolution to probe the soot inception and growth chemistry than flat flames. Second, we wish to examine the feasibility of determining the laminar flame speed of soot forming flames. Our basic assumption is that under the adiabatic condition (in the absence of conductive heat loss), the amount and dynamics of soot formed in the flame is unique for a given fuel/air mixture. The laminar flame speed can be rigorously defined as long as the radiative heat loss can be determined. This laminar flame speed characterizes the flame soot formation and dynamics in addition to the heat release rate. The research involves two integral parts: experiments of spherical and cylindrical sooting flames in microgravity (CWRU), and the computational counterpart (UD) that aims to simulate sooting laminar flames, and the sooting limits of near adiabatic flames. The computations work is described in this report, followed by a summary of the accomplishments achieved to date. Details of the microgra+ experiments will be discussed in a separate, final report prepared by the co-PI, Professor C-J. Sung of CWRU. Here only a brief discussion of these experiments will be given.

  10. Co-formation and co-release of genotoxic PAHs, alkyl-PAHs and soot nanoparticles from gasoline direct injection vehicles

    NASA Astrophysics Data System (ADS)

    Muñoz, Maria; Haag, Regula; Honegger, Peter; Zeyer, Kerstin; Mohn, Joachim; Comte, Pierre; Czerwinski, Jan; Heeb, Norbert V.

    2018-04-01

    Gasoline direct injection (GDI) vehicles quickly replace traditional port-fuel injection (PFI) vehicles in Europe reaching about 50 million vehicles on roads in 2020. GDI vehicles release large numbers of soot nanoparticles similar to conventional diesel vehicles without particle filters. These exhausts will increasingly affect air quality in European cities. We hypothesized that such particles are released together with polycyclic aromatic hydrocarbons (PAHs) formed under the same combustion conditions. Emission data of a fleet of 7 GDI vehicles (1.2-1.8 L) including Euro-3,-4,-5 and -6 technologies revealed substantial particle emissions on average of 2.5 × 1012 particles km-1 in the cold worldwide harmonized light vehicle test cycle (cWLTC), the future European legislative driving cycle. Particle emissions increased 2-3 orders of magnitude during acceleration like CO, indicating that transient driving produces fuel-rich conditions with intense particle formation. For comparison, an Euro-5 diesel vehicle (1.6 L) equipped with a particle filter released 3.9 × 1010 particles km-1 (cWLTC), clearly within the Euro-5/6 limit value of 6.0 × 1011 particles km-1 and 64-fold below the GDI fleet average. PAH and alkyl-PAH emissions of the GDI vehicles also exceeded those of the diesel vehicle. Mean GDI emissions of 2-, 3-, 4-, 5- and 6-ring PAHs in the cWLTC were 240, 44, 5.8, 0.5 and 0.4 μg km-1, those of the diesel vehicle were only 8.8, 7.1, 8.6, 0.02 and 0.02 μg km-1, respectively. Thus mean PAH emissions of the GDI fleet were 2 orders of magnitude higher than the bench mark diesel vehicle. A comparison of the toxicity equivalent concentrations (TEQ) in the cWLTC of the GDI fleet and the diesel vehicle revealed that GDI vehicles released 200-1700 ng TEQ m-3 genotoxic PAHs, being 6-40 times higher than the diesel vehicle with 45 ng TEQ km-1. The co-release of genotoxic PAHs adsorbed on numerous soot nanoparticles is critical due to the Trojan horse effect

  11. Characterisation of diesel particulate emission from engines using commercial diesel and biofuels

    NASA Astrophysics Data System (ADS)

    Ajtai, T.; Pintér, M.; Utry, N.; Kiss-Albert, G.; Gulyás, G.; Pusztai, P.; Puskás, R.; Bereczky, Á.; Szabados, Gy.; Szabó, G.; Kónya, Z.; Bozóki, Z.

    2016-06-01

    In this paper, the number concentration and the size distribution of diluted diesel exhaust particulate matter were measured at three different engine operating points in the speed-load range of the engine as follows: 1600 rpm; 50% load, 1900 rpm; 25% load, 1900 rpm; 75% load, adopted from the UN ECE Vehicle Regulation no. 49 (Revision 2) test protocol using pure diesel and biodiesel fuels, as well as their controlled blends. The emitted particulate assembly had lognormal size distribution in the accumulation mode regardless of the engine operational condition and the type of fuel. The total number and volume concentration emitted by the diesel engine decreased with increasing revolution per minute and rated torque in case of all the fuel types. The mixing ratio of the fuels did not linearly affect the total emission but had a minimum at 75% biodiesel content. We also studied the thermal evolution of the emitted particulates using a specially designed thermodenuder (TD) heated at specific temperatures (50 °C, 120 °C, and 250 °C). The first transition, when the temperature was increased from 50 °C to 120 °C resulted in lower number concentrations with small relative shifts of the peak position. However, in case of the second transition, when the temperature reached 250 °C the individual volatile particulates adsorbed onto the surface of soot particles were completely or partly vaporised resulting in lower total number concentrations with a substantial shift in peak position.

  12. Acoustic filtration and sedimentation of soot particles

    NASA Astrophysics Data System (ADS)

    Martin, K. M.; Ezekoye, O. A.

    Removal of soot particles from a static chamber by an intense acoustic field is investigated. Combustion of a solid fuel fills a rectangular chamber with small soot particles, which sediment very slowly. The chamber is then irradiated by an intense acoustic source to produce a three dimensional standing wave field in the chamber. The acoustic excitation causes the soot particles to agglomerate, forming larger particles which sediment faster from the system. The soot also forms 1-2 cm disks, with axes parallel to the axis of the acoustic source, which are levitated by the sound field at half-wavelength spacing within the chamber. Laser extinction measurements are made to determine soot volume fractions as a function of exposure time within the chamber. The volume fraction is reduced over time by sedimentation and by particle migration to the disks. The soot disks are considered to be a novel mechanism for particle removal from the air stream, and this mechanism has been dubbed acoustic filtration. An experimental method is developed for comparing the rate of soot removal by sedimentation alone with the rate of soot removal by sedimentation and acoustic filtration. Results show that acoustic filtration increases the rate of soot removal by a factor of two over acoustically-induced sedimentation alone.

  13. Light changes the atmospheric reactivity of soot

    PubMed Central

    Monge, Maria Eugenia; D’Anna, Barbara; Mazri, Linda; Giroir-Fendler, Anne; Ammann, Markus; Donaldson, D. J.; George, Christian

    2010-01-01

    Soot particles produced by incomplete combustion processes are one of the major components of urban air pollution. Chemistry at their surfaces lead to the heterogeneous conversion of several key trace gases; for example NO2 interacts with soot and is converted into HONO, which rapidly photodissociates to form OH in the troposphere. In the dark, soot surfaces are rapidly deactivated under atmospheric conditions, leading to the current understanding that soot chemistry affects tropospheric chemical composition only in a minor way. We demonstrate here that the conversion of NO2 to HONO on soot particles is drastically enhanced in the presence of artificial solar radiation, and leads to persistent reactivity over long periods. Soot photochemistry may therefore be a key player in urban air pollution. PMID:20080580

  14. Toxicological characterization of diesel engine emissions using biodiesel and a closed soot filter

    NASA Astrophysics Data System (ADS)

    Kooter, Ingeborg M.; van Vugt, Marcel A. T. M.; Jedynska, Aleksandra D.; Tromp, Peter C.; Houtzager, Marc M. G.; Verbeek, Ruud P.; Kadijk, Gerrit; Mulderij, Mariska; Krul, Cyrille A. M.

    2011-03-01

    This study was designed to determine the toxicity (oxidative stress, cytotoxicity, genotoxicity) in extracts of combustion aerosols. A typical Euro III heavy truck engine was tested over the European Transient Cycle with three different fuels: conventional diesel EN590, biodiesel EN14214 as B100 and blends with conventional diesel (B5, B10, and B20) and pure plant oil DIN51605 (PPO). In addition application of a (wall flow) diesel particulate filter (DPF) with conventional diesel EN590 was tested. The use of B100 or PPO as a fuel or the DPF reduced particulate matter (PM) mass and numbers over 80%. Similarly, significant reduction in the emission of chemical constituents (EC 90%, (oxy)-PAH 70%) were achieved. No significant changes in nitro-PAH were observed. The use of B100 or PPO led to a NOx increase of about 30%, and no increase for DPF application. The effects of B100, PPO and the DPF on the biological test results vary strongly from positive to negative depending on the biological end point. The oxidative potential, measured via the DTT assay, of the B100 and PPO or DPF emissions is reduced by 95%. The cytotoxicity is increased for B100 by 200%. The measured mutagenicity, using the Ames assay test with TA98 and YG1024 strains of Salmonella typhimurium indicate a dose response for the nitroarene sensitive YG1024 strain for B100 and PPO (fold induction: 1.6). In summary B100 and PPO have good potential for the use as a second generation biofuel resulting in lower PM mass, similar to application of a DPF, but caution should be made due to potential increased toxicity. Besides regulation via mass, the biological reactivity of exhaust emissions of new (bio)fuels and application of new technologies, needs attention. The different responses of different biological tests as well as differences in results between test laboratories underline the need for harmonization of test methods and international cooperation.

  15. Electrically heated particulate matter filter soot control system

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gonze, Eugene V.; Paratore, Jr., Michael J.; Bhatia, Garima

    A regeneration system includes a particulate matter (PM) filter with an upstream end for receiving exhaust gas and a downstream end. A control module determines a current soot loading level of the PM filter and compares the current soot loading level to a predetermined soot loading level. The control module permits regeneration of the PM filter when the current soot loading level is less than the predetermined soot loading level.

  16. Maternal Diesel Inhalation Increases Airway Hyperreactivity in Ozone Exposed Offspring

    EPA Science Inventory

    Air pollutant exposure is linked with childhood asthma incidence and exacerbations, and maternal exposure to airborne pollutants during pregnancy increases airway hyperreactivity (ARR) in offspring. To determine if exposure to diesel exhaust during pregnancy worsened postnatal oz...

  17. Effects of biodiesel, engine load and diesel particulate filter on nonvolatile particle number size distributions in heavy-duty diesel engine exhaust.

    PubMed

    Young, Li-Hao; Liou, Yi-Jyun; Cheng, Man-Ting; Lu, Jau-Huai; Yang, Hsi-Hsien; Tsai, Ying I; Wang, Lin-Chi; Chen, Chung-Bang; Lai, Jim-Shoung

    2012-01-15

    Diesel engine exhaust contains large numbers of submicrometer particles that degrade air quality and human health. This study examines the number emission characteristics of 10-1000 nm nonvolatile particles from a heavy-duty diesel engine, operating with various waste cooking oil biodiesel blends (B2, B10 and B20), engine loads (0%, 25%, 50% and 75%) and a diesel oxidation catalyst plus diesel particulate filter (DOC+DPF) under steady modes. For a given load, the total particle number concentrations (N(TOT)) decrease slightly, while the mode diameters show negligible changes with increasing biodiesel blends. For a given biodiesel blend, both the N(TOT) and mode diameters increase modestly with increasing load of above 25%. The N(TOT) at idle are highest and their size distributions are strongly affected by condensation and possible nucleation of semivolatile materials. Nonvolatile cores of diameters less than 16 nm are only observed at idle mode. The DOC+DPF shows remarkable filtration efficiency for both the core and soot particles, irrespective of the biodiesel blend and engine load under study. The N(TOT) post the DOC+DPF are comparable to typical ambient levels of ≈ 10(4)cm(-3). This implies that, without concurrent reductions of semivolatile materials, the formation of semivolatile nucleation mode particles post the after treatment is highly favored. Copyright © 2011 Elsevier B.V. All rights reserved.

  18. Structure and Soot Formation Properties of Laminar Flames

    NASA Technical Reports Server (NTRS)

    El-Leathy, A. M.; Xu, F.; Faeth, G. M.

    2001-01-01

    Soot formation within hydrocarbon-fueled flames is an important unresolved problem of combustion science for several reasons: soot emissions are responsible for more deaths than any other combustion-generated pollutant, thermal loads due to continuum radiation from soot limit the durability of combustors, thermal radiation from soot is mainly responsible for the growth and spread of unwanted fires, carbon monoxide emissions associated with soot emissions are responsible for most fire deaths, and limited understanding of soot processes in flames is a major impediment to the development of computational combustion. Motivated by these observations, soot processes within laminar premixed and nonpremixed (diffusion) flames are being studied during this investigation. The study is limited to laminar flames due to their experimental and computational tractability, noting the relevance of these results to practical flames through laminar flamelet concepts. Nonbuoyant flames are emphasized because buoyancy affects soot processes in laminar diffusion flames whereas effects of buoyancy are small for most practical flames. This study involves both ground- and space-based experiments, however, the following discussion will be limited to ground-based experiments because no space-based experiments were carried out during the report period. The objective of this work was to complete measurements in both premixed and nonpremixed flames in order to gain a better understanding of the structure of the soot-containing region and processes of soot nucleation and surface growth in these environments, with the latter information to be used to develop reliable ways of predicting soot properties in practical flames. The present discussion is brief, more details about the portions of the investigation considered here can be found in refs. 8-13.

  19. Oxidant generation and toxicity enhancement of aged-diesel exhaust

    NASA Astrophysics Data System (ADS)

    Li, Qianfeng; Wyatt, Anna; Kamens, Richard M.

    Diesel exhaust related airborne Particulate Matter (PM) has been linked to a myriad of adverse health outcomes, ranging from cancer to cardiopulmonary disease. The underlying toxicological mechanisms are of great scientific interest. A hypothesis under investigation is that many of the adverse health effects may derive from oxidative stress, initiated by the formation of reactive oxygen species (ROS) within affected cells. In this study, the main objective was to determine whether aged-diesel exhaust PM has a higher oxidant generation and toxicity than fresh diesel exhaust PM. The diesel exhaust PM was generated from a 1980 Mercedes-Benz model 300SD, and a dual 270 m 3 Teflon film chamber was utilized to generate two test atmospheres. One side of the chamber is used to produce ozone-diesel exhaust PM system, and another side of the chamber was used to produce diesel exhaust PM only system. A newly optimized dithiothreitol (DTT) method was used to assess their oxidant generation and toxicity. The results of this study showed: (1) both fresh and aged-diesel exhaust PM had high oxidant generation and toxicity; (2) ozone-diesel exhaust PM had a higher toxicity response than diesel exhaust PM only; (3) the diesel exhaust PM toxicity increased with time; (4) the optimized DTT method could be used as a good quantitative chemical assay for oxidant generation and toxicity measurement.

  20. Laser Scanning Microscopic Investigations of the Decontamination of Soot Nanoparticles from the Skin.

    PubMed

    Lademann, Jürgen; Knorr, Fanny; Patzelt, Alexa; Meinke, Martina C; Richter, Heike; Krutmann, Jean; Rühl, Eckart; Doucet, Olivier

    2018-01-01

    Airborne pollutants, such as nano-sized soot particles, are increasingly being released into the environment as a result of growing population densities and industrialization. They can absorb organic and metal compounds with potential biological activity, such as polycyclic aromatic hydrocarbons and airborne pollen allergens. Local and systemic toxicities may be induced in the skin if the particulates release their harmful components upon dermal contact. In the present study, skin pretreatments with serum and/or shield as barrier formulations prior to exposure and washing with a cleanser subsequent to exposure were evaluated as a protection and decontamination strategy using laser scanning microscopy. The results indicate that while the application of serum and a cleanser was insufficient for decontamination, the pretreatment with shield prior to nanoparticle exposure followed by washing led to the removal of a considerable amount of the carbon black particles. The combined application of serum and shield before the administration of carbon black particles and subsequent washing led to their elimination from the skin samples. The application of barrier-enhancing formulations in combination with a cleanser may reduce the penetration of harmful airborne particulates by preventing their adhesion to the skin and facilitating their removal by subsequent washing with the cleanser. © 2018 S. Karger AG, Basel.

  1. Automated classification of single airborne particles from two-dimensional angle-resolved optical scattering (TAOS) patterns by non-linear filtering

    NASA Astrophysics Data System (ADS)

    Crosta, Giovanni Franco; Pan, Yong-Le; Aptowicz, Kevin B.; Casati, Caterina; Pinnick, Ronald G.; Chang, Richard K.; Videen, Gorden W.

    2013-12-01

    Measurement of two-dimensional angle-resolved optical scattering (TAOS) patterns is an attractive technique for detecting and characterizing micron-sized airborne particles. In general, the interpretation of these patterns and the retrieval of the particle refractive index, shape or size alone, are difficult problems. By reformulating the problem in statistical learning terms, a solution is proposed herewith: rather than identifying airborne particles from their scattering patterns, TAOS patterns themselves are classified through a learning machine, where feature extraction interacts with multivariate statistical analysis. Feature extraction relies on spectrum enhancement, which includes the discrete cosine FOURIER transform and non-linear operations. Multivariate statistical analysis includes computation of the principal components and supervised training, based on the maximization of a suitable figure of merit. All algorithms have been combined together to analyze TAOS patterns, organize feature vectors, design classification experiments, carry out supervised training, assign unknown patterns to classes, and fuse information from different training and recognition experiments. The algorithms have been tested on a data set with more than 3000 TAOS patterns. The parameters that control the algorithms at different stages have been allowed to vary within suitable bounds and are optimized to some extent. Classification has been targeted at discriminating aerosolized Bacillus subtilis particles, a simulant of anthrax, from atmospheric aerosol particles and interfering particles, like diesel soot. By assuming that all training and recognition patterns come from the respective reference materials only, the most satisfactory classification result corresponds to 20% false negatives from B. subtilis particles and <11% false positives from all other aerosol particles. The most effective operations have consisted of thresholding TAOS patterns in order to reject defective ones

  2. Soot Formation in Hydrocarbon/Air Laminar Jet Diffusion Flames

    NASA Technical Reports Server (NTRS)

    Sunderland, P. B.; Faeth, G. M.

    1994-01-01

    Soot processes within hydrocarbon/air diffusion flames are important because they affect the durability and performance of propulsion systems, the hazards of unwanted fires, the pollutant and particulate emissions from combustion processes, and the potential for developing computational combustion. Motivated by these observations, this investigation involved an experimental study of the structure and soot properties of round laminar jet diffusion flames, seeking an improved understanding of soot formation (growth and nucleation) within diffusion flames. The present study extends earlier work in this laboratory concerning laminar smoke points (l) and soot formation in acetylene/air laminar jet diffusion flames (2), emphasizing soot formation in hydrocarbon/air laminar jet diffusion flames for fuels other than acetylene. In the flame system, acetylene is the dominant gas species in the soot formation region and both nucleation and growth were successfully attributed to first-order reactions of acetylene, with nucleation exhibiting an activation energy of 32 kcal/gmol while growth involved negligible activation energy and a collision efficiency of O.53%. In addition, soot growth in the acetylene diffusion flames was comparable to new soot in premixed flame (which also has been attributed to first-order acetylene reactions). In view of this status, a major issue is the nature of soot formation processes in diffusion flame involving hydrocarbon fuels other than acetylene. In particular, information is needed about th dominant gas species in the soot formation region and the impact of gas species other than acetylene on soot nucleation and growth.

  3. Soot Formation in Freely-Propagating Laminar Premixed Flames

    NASA Technical Reports Server (NTRS)

    Lin, K.-C.; Hassan, M. I.; Faeth, G. M.

    1997-01-01

    Soot formation within hydrocarbon-fueled flames is an important unresolved problem of combustion science. Thus, the present study is considering soot formation in freely-propagating laminar premixed flames, exploiting the microgravity environment to simplify measurements at the high-pressure conditions of interest for many practical applications. The findings of the investigation are relevant to reducing emissions of soot and continuum radiation from combustion processes, to improving terrestrial and spacecraft fire safety, and to developing methods of computational combustion, among others. Laminar premixed flames are attractive for studying soot formation because they are simple one-dimensional flows that are computationally tractable for detailed numerical simulations. Nevertheless, studying soot-containing burner-stabilized laminar premixed flames is problematical: spatial resolution and residence times are limited at the pressures of interest for practical applications, flame structure is sensitive to minor burner construction details so that experimental reproducibility is not very good, consistent burner behavior over the lengthy test programs needed to measure soot formation properties is hard to achieve, and burners have poor durability. Fortunately, many of these problems are mitigated for soot-containing, freely-propagating laminar premixed flames. The present investigation seeks to extend work in this laboratory for various soot processes in flames by observing soot formation in freely-propagating laminar premixed flames. Measurements are being made at both Normal Gravity (NG) and MicroGravity (MG), using a short-drop free-fall facility to provide MG conditions.

  4. Diamonds in detonation soot

    NASA Technical Reports Server (NTRS)

    Greiner, N. Roy; Phillips, Dave; Johnson, J. D.; Volk, Fred

    1990-01-01

    Diamonds 4 to 7 nm in diameter have been identified and partially isolated from soot formed in detonations of carbon-forming composite explosives. The morphology of the soot has been examined by transmission electron microscopy (TEM), and the identity of the diamond has been established by the electron diffraction pattern of the TEM samples and by the X-ray diffraction (XRD) pattern of the isolated solid. Graphite is also present in the form of ribbons of turbostatic structure with a thickness of 2 to 4 nm. A fraction, about 25 percent of the soot by weight, was recovered from the crude soot after oxidation of the graphite with fuming perchloric acid. This fraction showed a distinct XRD pattern of diamond and the diffuse band of amorphous carbon. The IR spectrum of these diamonds closely matches that of diamonds recovered from meteorites (Lewis et al., 1987), perhaps indicating similar surface properties after the oxidation. If these diamonds are produced in the detonation itself or during the initial expansion, they exhibit a phenomenal crystal growth rate (5 nm/0.00001 s equal 1.8 m/hr) in a medium with a very low hydrogen/carbon ratio. Because the diamonds will be carried along with the expanding gases, they will be accelerated to velocities approaching 8 km/s.

  5. Investigation of methyl decanoate combustion in an optical direct-injection diesel engine

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cheng, A. S.; Dumitrescu, Cosmin E.; Mueller, Charles J.

    In this study, an optically accessible heavy-duty diesel engine was used to investigate the impact of methyl decanoate (MD) on combustion and emissions. A specific goal of the study was to determine if MD could enable soot-free leaner-lifted flame combustion (LLFC) – a mode of mixing-controlled combustion associated with fuel-air equivalence ratios below approximately two. An ultra-low sulfur diesel certification fuel (CF) was used as the baseline fuel, and experiments were conducted at two fuel-injection pressures with three levels of charge-gas dilution. In addition to conventional pressure-based and engine-out emissions measurements, exhaust laser-induced incandescence, in-cylinder natural luminosity (NL), and in-cylindermore » chemiluminescence (CL) diagnostics were used to provide detailed insight into combustion processes.« less

  6. Investigation of methyl decanoate combustion in an optical direct-injection diesel engine

    DOE PAGES

    Cheng, A. S.; Dumitrescu, Cosmin E.; Mueller, Charles J.

    2014-11-24

    In this study, an optically accessible heavy-duty diesel engine was used to investigate the impact of methyl decanoate (MD) on combustion and emissions. A specific goal of the study was to determine if MD could enable soot-free leaner-lifted flame combustion (LLFC) – a mode of mixing-controlled combustion associated with fuel-air equivalence ratios below approximately two. An ultra-low sulfur diesel certification fuel (CF) was used as the baseline fuel, and experiments were conducted at two fuel-injection pressures with three levels of charge-gas dilution. In addition to conventional pressure-based and engine-out emissions measurements, exhaust laser-induced incandescence, in-cylinder natural luminosity (NL), and in-cylindermore » chemiluminescence (CL) diagnostics were used to provide detailed insight into combustion processes.« less

  7. Emissions of soot particles from heat generators

    NASA Astrophysics Data System (ADS)

    Lyubov, V. K.; Popov, A. N.; Popova, E. I.

    2017-11-01

    «Soot carbon» or «Soot» - incomplete combustion or thermal decomposition particulate carbon product of hydrocarbons consisting of particles of various shapes and sizes. Soot particles are harmful substances Class 2 and like a dust dispersed by wind for thousands of kilometers. Soot have more powerful negative factor than carbon dioxide. Therefore, more strict requirements on ecological and economical performance for energy facilities at Arctic areas have to be developed to protect fragile Arctic ecosystems and global climate change from degradation and destruction. Quantity of soot particles in the flue gases of energy facilities is a criterion of effectiveness for organization of the burning process. Some of heat generators do not provide the required energy and environmental efficiency which results in irrational use of energy resources and acute pollution of environment. The paper summarizes the results of experimental study of solid particles emission from wide range of capacity boilers burning different organic fuels (natural gas, fuel oil, coal and biofuels). Special attention is paid to environmental and energy performance of the biofuels combustion. Emissions of soot particles PM2.5 are listed. Structure, composition and dimensions of entrained particles with the use of electronic scanning microscope Zeiss SIGMA VP were also studied. The results reveal an impact of several factors on soot particles emission.

  8. Physico-chemical properties and biological effects of diesel and biomass particles.

    PubMed

    Longhin, Eleonora; Gualtieri, Maurizio; Capasso, Laura; Bengalli, Rossella; Mollerup, Steen; Holme, Jørn A; Øvrevik, Johan; Casadei, Simone; Di Benedetto, Cristiano; Parenti, Paolo; Camatini, Marina

    2016-08-01

    Diesel combustion and solid biomass burning are the major sources of ultrafine particles (UFP) in urbanized areas. Cardiovascular and pulmonary diseases, including lung cancer, are possible outcomes of combustion particles exposure, but differences in particles properties seem to influence their biological effects. Here the physico-chemical properties and biological effects of diesel and biomass particles, produced under controlled laboratory conditions, have been characterized. Diesel UFP were sampled from a Euro 4 light duty vehicle without DPF fuelled by commercial diesel and run over a chassis dyno. Biomass UFP were collected from a modern automatic 25 kW boiler propelled by prime quality spruce pellet. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images of both diesel and biomass samples showed aggregates of soot particles, but in biomass samples ash particles were also present. Chemical characterization showed that metals and PAHs total content was higher in diesel samples compared to biomass ones. Human bronchial epithelial (HBEC3) cells were exposed to particles for up to 2 weeks. Changes in the expression of genes involved in xenobiotic metabolism were observed after exposure to both UFP already after 24 h. However, only diesel particles modulated the expression of genes involved in inflammation, oxidative stress and epithelial-to-mesenchymal transition (EMT), increased the release of inflammatory mediators and caused phenotypical alterations, mostly after two weeks of exposure. These results show that diesel UFP affected cellular processes involved in lung and cardiovascular diseases and cancer. Biomass particles exerted low biological activity compared to diesel UFP. This evidence emphasizes that the study of different emission sources contribution to ambient PM toxicity may have a fundamental role in the development of more effective strategies for air quality improvement. Copyright © 2016 Elsevier Ltd. All rights

  9. Experimental study on filtration and continuous regeneration of a particulate filter system for heavy-duty diesel engines.

    PubMed

    Tang, Tao; Zhang, Jun; Cao, Dongxiao; Shuai, Shijin; Zhao, Yanguang

    2014-12-01

    This study investigated the filtration and continuous regeneration of a particulate filter system on an engine test bench, consisting of a diesel oxidation catalyst (DOC) and a catalyzed diesel particulate filter (CDPF). Both the DOC and the CDPF led to a high conversion of NO to NO2 for continuous regeneration. The filtration efficiency on solid particle number (SPN) was close to 100%. The post-CDPF particles were mainly in accumulation mode. The downstream SPN was sensitively influenced by the variation of the soot loading. This phenomenon provides a method for determining the balance point temperature by measuring the trend of SPN concentration. Copyright © 2014. Published by Elsevier B.V.

  10. Laminar Soot Processes

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The Laminar Soot Processes (LSP) experiment under way during the Microgravity Sciences Lab-1 mission in 1997. LSP-2 will fly in the STS-107 Research 1 mission in 2001. The principal investigator is Dr. Gerard Faeth of the University of Michigan. LSP uses a small jet burner, similar to a classroom butane lighter, that produces flames up to 60 mm (2.3 in) long. Measurements include color TV cameras and a temperature sensor, and laser images whose darkness indicates the quantity of soot produced in the flame. Glenn Research in Cleveland, OH, manages the project.

  11. Water interaction with hydrophobic and hydrophilic soot particles.

    PubMed

    Popovicheva, Olga; Persiantseva, Natalia M; Shonija, Natalia K; DeMott, Paul; Koehler, Kirsten; Petters, Markus; Kreidenweis, Sonia; Tishkova, Victoria; Demirdjian, Benjamin; Suzanne, Jean

    2008-05-07

    The interaction of water with laboratory soots possessing a range of properties relevant for atmospheric studies is examined by two complementary methods: gravimetrical measurement of water uptake coupled with chemical composition and porosity analysis and HTDMA (humidified tandem differential mobility analyzer) inference of water uptake accompanied by separate TEM (transmission electron microscopy) analysis of single particles. The first method clarifies the mechanism of water uptake for bulk soot and allows the classification of soot with respect to its hygroscopicity. The second method highlights the dependence of the soot aerosol growth factor on relative humidity (RH) for quasi-monodisperse particles. Hydrophobic and hydrophilic soot are qualitatively defined by their water uptake and surface polarity: laboratory soot particles are thus classified from very hydrophobic to very hydrophilic. Thermal soot particles produced from natural gas combustion are classified as hydrophobic with a surface of low polarity since water is found to cover only half of the surface. Graphitized thermal soot particles are proposed for comparison as extremely hydrophobic and of very low surface polarity. Soot particles produced from laboratory flame of TC1 aviation kerosene are less hydrophobic, with their entire surface being available for statistical monolayer water coverage at RH approximately 10%. Porosity measurements suggest that, initially, much of this surface water resides within micropores. Consequently, the growth factor increase of these particles to 1.07 at RH > 80% is attributed to irreversible swelling that accompanies water uptake. Hysteresis of adsorption/desorption cycles strongly supports this conclusion. In contrast, aircraft engine soot, produced from burning TC1 kerosene in a gas turbine engine combustor, has an extremely hydrophilic surface of high polarity. Due to the presence of water soluble organic and inorganic material it can be covered by many water

  12. Conductivity for soot sensing: possibilities and limitations.

    PubMed

    Grob, Benedikt; Schmid, Johannes; Ivleva, Natalia P; Niessner, Reinhard

    2012-04-17

    In this study we summarize the possibilities and limitations of a conductometric measurement principle for soot sensing. The electrical conductivity of different carbon blacks (FW 200, lamp black 101, Printex 30, Printex U, Printex XE2, special black 4, and special black 6), spark discharge soot (GfG), and graphite powder was measured by a van der Pauw arrangement. Additionally the influence of inorganic admixtures on the conductivity of carbonaceous materials was proven to follow the percolation theory. Structural and oxidation characteristics obtained with Raman microspectroscopy and temperature programmed oxidation, respectively, were correlated with the electrical conductivity data. Moreover, a thermophoretic precipitator has been applied to deposit soot particles from the exhaust stream between interdigital electrodes. This combines a controlled and size independent particle collection method with the conductivity measurement principle. A test vehicle was equipped with the AVL Micro Soot Sensor (photoacoustic soot sensor) to prove the conductometric sensor principle with an independent and reliable technique. Our results demonstrate promising potential of the conductometric sensor for on-board particle diagnostic. Furthermore this sensor can be applied as a simple, rapid, and cheap analytical tool for characterization of soot structure.

  13. Combustion Performance and Exhaust Emission of DI Diesel Engine Using Various Sources of Waste Cooking Oil

    NASA Astrophysics Data System (ADS)

    Afiq, Mohd; Azuhairi, Mohd; Jazair, Wira

    2010-06-01

    In Malaysia, more than 200-tone of cooking oil are used by domestic users everyday. After frying process, about a quarter of these cooking oil was remained and drained into sewage system. This will pollutes waterways and affects the ecosystem. The use of waste cooking oil (WCO) for producing bio-diesel was considered in economical factor which current production cost of bio-diesel production is higher in Malaysia due to higher price of palm oil. Thus, the aim of this study is to investigate the most suitable source of WCO to become a main source of bio-diesel for bio-diesel production in this country. To perform this research, three type of WCO were obtained from house's kitchen, cafeteria and mamak's restaurant. In this study, prospect of these bio-diesel source was evaluated based on its combustion performance and exhaust emissions operated in diesel engine in the form of waste cooking oil methyl ester (WCOME) and have been compared with pure diesel fuel. A 0.6 liter, single-cylinder, air-cooled direct injection diesel engine was used to perform this experiment. Experiment was done at variable engine loads and constant engine speed. As the result, among three stated WCOMEs, the one collected from house's kitchen gives the best performance in term of brake specific fuel consumption (bsfc) and brake power (BP) with lowest soot emission.

  14. Lanthanum-promoted copper-based hydrotalcites derived mixed oxides for NO{sub x} adsorption, soot combustion and simultaneous NO{sub x}-soot removal

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Zhongpeng; Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR; Yan, Xiaotong

    Graphical abstract: - Highlights: • The addition of La in Cu-based oxides increased the types of active oxygen. • NO{sub x} adsorption, soot oxidation and simultaneous NO{sub x}-soot removal were enhanced. • The possible catalytic mechanism was studied via in situ FTIR analysis. • Soot oxidation was promoted by the NO{sub 2} intermediate. - Abstract: La-promoted Cu-based hydrotalcites derived mixed oxides were prepared and their catalytic activities for NO{sub x} adsorption, soot oxidation, and simultaneous NO{sub x}-soot removal were investigated. The catalysts were characterized by XRD, DTG, BET, FTIR, H2-TPR, TPD and TPO techniques. The oxides catalysts exhibited mesoporous propertiesmore » with specific surface area of 45–160 m{sup 2}/g. The incorporation of La and Cu decreased the amount of basic sites due to the large decrease in surface areas. Under O{sub 2} atmosphere, La incorporation is dominant for soot oxidation activity, while Cu favors high selectivity to CO{sub 2} formation. A synergetic effect between La and Cu for catalyzed soot oxidation lies in the improved redox property and suitable basicity. The presence of NO in O{sub 2} significantly promoted soot oxidation on the catalysts with the ignition temperature decreased to about 300 °C. In O{sub 2}/NO atmosphere, NO{sub 2} acts as an intermediate which oxidizes soot to CO{sub 2} at a lower temperature with itself reduced to NO or N{sub 2}, contributing to the high catalytic performance in simultaneous removal of NO{sub x} and soot.« less

  15. Research of biofuels on performance, emission and noise of diesel engine under high-altitude area

    NASA Astrophysics Data System (ADS)

    Xu, Kai; Huang, Hua

    2018-05-01

    At high altitudes and with no any adjustment for diesel engine, comparative experiments on a diesel engine about the engine's performance, emission and exhaust noise, are carried out by combusting different biofuels (pure diesel (D100), biodiesel (B100), and ethanol-biodiesel (E20)). The test results show that: compared with D100, the power performance of combusting B100 and E20 decreases, and the average drop of the torque at full-load are 4.5% and 5.7%. The equivalent fuel consumption is lower than that of diesel fuel, The decline of oil consumption rate 3˜10g/ (kW • h); At low load the emission of NOx decreases, Hat high loads, equal and higher than D100; the soot emissions decreases heavier, among them, E20 carbon dioxide emissions improved considerably; An full-load exhaust noise of B100 decreases average 3.6dB(A), E20 decreases average 4.8dB(A); In road simulation experiments exhaust noise max decreases 8.5dB(A).

  16. Soot Surface Growth in Laminar Hydrocarbon/Air Diffusion Flames. Appendix J

    NASA Technical Reports Server (NTRS)

    El-Leathy, A. M.; Xu, F.; Kim, C. H.; Faeth, G. M.; Yuan, Z.-G. (Technical Monitor); Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

    2003-01-01

    The structure and soot surface growth properties of round laminar jet diffusion flames were studied experimentally. Measurements were made along the axes of ethylene-, propylene-propane- and acetylene-benzene-fueled flames burning in coflowing air at atmospheric pressure with the reactants at normal temperature. The measurements included soot structure, soot concentrations, soot temperatures, major gas species concentrations, some radial species (H, OH and 0) concentrations, and gas velocities. These measurements yielded the local flame properties that are thought to affect soot surface growth as well as local soot surface growth rates. When present results were combined with similar earlier observations of acetylene-fueled laminar jet diffusion flames, the results suggested that soot surface growth involved decomposition of the original fuel to form acetylene and H, which were the main reactants for soot surface growth, and that the main effect of the parent fuel on soot surface growth involved its yield of acetylene and H for present test conditions. Thus, as the distance increased along the axes of the flames, soot formation (which was dominated by soot surface growth) began near the cool core of the flow once acetylene and H appeared together and ended near the flame sheet when acetylene disappeared. Species mainly responsible for soot oxidation - OH and 02 were present throughout the soot formation region so that soot surface growth and oxidation proceeded at the same time. Present measurements of soot surface growth rates (corrected for soot surface oxidation) in laminar jet diffusion flames were consistent with earlier measurements of soot surface growth rates in laminar premixed flames and exhibited good agreement with existing Hydrogen-Abstraction/Carbon-Addition (HACA) soot surface growth mechanisms in the literature with steric factors in these mechanisms having values on the order of unity, as anticipated.

  17. Soot Surface Growth in Laminar Hydrocarbon/Air Diffusion Flames. Appendix B

    NASA Technical Reports Server (NTRS)

    El-Leathy, A. M.; Xu, F.; Kim, C. H.; Faeth, G. M.; Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

    2001-01-01

    The structure and soot surface growth properties of round laminar jet diffusion flames were studied experimentally. Measurements were made along the axes of ethylene-, propylene-propane- and acetylene-benzene-fueled flames burning in coflowing air at atmospheric pressure with the reactants at normal temperature. The measurements included soot structure, soot concentrations, soot temperatures, major gas species concentrations, some radial species (H, OH and O) concentrations, and gas velocities. These measurements yielded the local flame properties that are thought to affect soot surface growth as well as local soot surface growth rates. When present results were combined with similar earlier observations of acetylene-fueled laminar jet diffusion flames, the results suggested that soot surface growth involved decomposition of the original fuel to form acetylene and H, which were the main reactants for soot surface growth, and that the main effect of the parent fuel on soot surface growth involved its yield of acetylene and H for present test conditions. Thus, as the distance increased along the axes of the flames, soot formation (which was dominated by soot surface growth) began near the cool core of the flow once acetylene and H appeared together and ended near the flame sheet when acetylene disappeared. Species mainly responsible for soot oxidation - OH and O2 were present throughout the soot formation region so that soot surface growth and oxidation proceeded at the same time. Present measurements of soot surface growth rates (corrected for soot surface oxidation) in laminar jet diffusion flames were consistent with earlier measurements of soot surface growth rates in laminar premixed flames and exhibited good agreement with existing Hydrogen-Abstraction/Carbon-Addition (HACA) soot surface growth mechanisms in the literature with steric factors in these mechanisms having values on the order of unity, as anticipated.

  18. Gasoline emissions dominate over diesel in formation of secondary organic aerosol mass

    NASA Astrophysics Data System (ADS)

    Bahreini, R.; Middlebrook, A. M.; de Gouw, J. A.; Warneke, C.; Trainer, M.; Brock, C. A.; Stark, H.; Brown, S. S.; Dube, W. P.; Gilman, J. B.; Hall, K.; Holloway, J. S.; Kuster, W. C.; Perring, A. E.; Prevot, A. S. H.; Schwarz, J. P.; Spackman, J. R.; Szidat, S.; Wagner, N. L.; Weber, R. J.; Zotter, P.; Parrish, D. D.

    2012-03-01

    Although laboratory experiments have shown that organic compounds in both gasoline fuel and diesel engine exhaust can form secondary organic aerosol (SOA), the fractional contribution from gasoline and diesel exhaust emissions to ambient SOA in urban environments is poorly known. Here we use airborne and ground-based measurements of organic aerosol (OA) in the Los Angeles (LA) Basin, California made during May and June 2010 to assess the amount of SOA formed from diesel emissions. Diesel emissions in the LA Basin vary between weekdays and weekends, with 54% lower diesel emissions on weekends. Despite this difference in source contributions, in air masses with similar degrees of photochemical processing, formation of OA is the same on weekends and weekdays, within the measurement uncertainties. This result indicates that the contribution from diesel emissions to SOA formation is zero within our uncertainties. Therefore, substantial reductions of SOA mass on local to global scales will be achieved by reducing gasoline vehicle emissions.

  19. PTV analysis of the entrained air into the diesel spray at high-pressure injection

    NASA Astrophysics Data System (ADS)

    Toda, Naoki; Yamashita, Hayato; Mashida, Makoto

    2014-08-01

    In order to clarify the effect of high-pressure injection on soot reduction in terms of the air entrainment into spray, the air flow surrounding the spray and set-off length indicating the distance from the nozzle tip to the flame region in diffusion diesel combustion were investigated using 300MPa injection of a multi-hole injector. The measurement of the air entrainment flow was carried out at non-evaporating condition using consecutive PTV (particle tracking velocimetry) method with a high-speed camera and a high-frequency pulse YAG laser. The set-off length was measured at highpressure and high-temperature using the combustion bomb of constant volume and optical system of shadow graph method. And the amount of air entrainment into spray until reaching set-off length in diffusion combustion was studied as a factor of soot formation.

  20. Volatile organic compounds and particulates as components of diesel engine exhaust gas

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Schulz, H.; Bandeira de Melo, G.; Ousmanov, F.

    1999-07-01

    Volatile organic compounds (VOC) and soot particles have been determined in a Diesel`s exhaust gas. A new sampling method allowed the measurement of emissions of organic compounds (C{sub 1} to C{sub 20}) in a gas chromatogram at a detection limit of ca. 0.2 mg/m{sup 3}. Particles were collected with a filter bed of ceramic particles and characterized by temperature programmed desorption (TPD) and oxidation (TPO). Engine runs were always performed at a fixed and constant air to fuel equivalence ratio ({lambda}) and with a constant volumetric efficiency, because these parameters strongly influenced the emissions in terms of both composition andmore » order of magnitude. The effective combustion temperature again strongly governed the nature of the emissions. Model fuels, composed of individual paraffins and aromatics and additions of sulfur compounds and an organic nitrate (for cetane number enhancement) were used. The results contribute to the understanding of the origin of specific emissions from Diesel engines. These newly developed methods are recommended for further application.« less

  1. Investigation of Sooting in Microgravity Droplet Combustion: Fuel-Dependent Effects

    NASA Technical Reports Server (NTRS)

    Manzello, Samuel L.; Hua, Ming; Choi, Mun Young

    1999-01-01

    Kumagai and coworkers first performed microgravity droplet combustion experiments [Kumagai, 1957]. The primary goal of these early experiments were to validate simple 'd(sup 2)-law models [Spalding, 1954, Godsave, 1954] Inherent in the 'd(sup 2) -law' formulation and in the scope of the experimental observation is the neglect of sooting behavior. In fact, the influence of sooting has not received much attention until more recent works [Choi et al., 1990; Jackson et al., 1991; Jackson and Avedisian, 1994; Choi and Lee, 1996; Jackson and Avedisian, 1996; Lee et al., 1998]:. Choi and Lee measured soot volume fraction for microgravity droplet flames using full-field light extinction and subsequent tomographic inversion [Choi and Lee, 1996]. In this investigation, soot concentrations were measured for heptane droplets and it was reported that soot concentrations were considerably higher in microgravity compared to the normal gravity flame. It was reasoned that the absence of buoyancy and the effects of thermophoresis resulted in the higher soot concentrations. Lee et al. [1998] performed soot measurement experiments by varying the initial droplet diameter and found marked influence of sooting on the droplet burning behavior. There is growing sentiment that sooting in droplet combustion must no longer be neglected and that "perhaps one of the most important outstanding contributions of (micro)g droplet combustion is the observation that in the absence of asymmetrical forced and natural convection, a soot shell is formed between the droplet surface and the flame, exerting an influence on the droplet combustion response far greater than previously recognized." [Law and Faeth, 1994]. One of the methods that we are exploring to control the degree of sooting in microgravity is to use different fuels. The effect of fuel structure on sooting propensity has been investigated for over-ventilated concentric coflowing buoyant diffusion flames. (Glassman, 1996]. In these

  2. Laminar Soot Processes

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Interior of the Equipment Module for the Laminar Soot Processes (LSP-2) experiment that fly in the STS-107 Research 1 mission in 2002 (LSP-1 flew on Microgravity Sciences Lab-1 mission in 1997). The principal investigator is Dr. Gerard Faeth of the University of Michigan. LSP uses a small jet burner (yellow ellipse), similar to a classroom butane lighter, that produces flames up to 60 mm (2.3 in) long. Measurements include color TV cameras and a radiometer or heat sensor (blue circle), and laser images whose darkness indicates the quantity of soot produced in the flame. Glenn Research in Cleveland, OH, manages the project.

  3. Flow/Soot-Formation Interactions in Nonbuoyant Laminar Diffusion Flames

    NASA Technical Reports Server (NTRS)

    Dai, Z.; Faeth, G. M.

    1999-01-01

    Nonpremixed (diffusion) flames are attractive for practical applications because they avoid the stability, autoignition, flashback, etc. problems of premixed flames. Unfortunately, soot formation in practical hydrocarbon-fueled diffusion flames reduces their attractiveness due to widely-recognized public health and combustor durability problems of soot emissions. For example, more deaths are attributed to the emission of soot (15,000-60,000 deaths annually in the U.S. alone) than any other combustion-generated pollutant. In addition, continuum radiation from soot-containing flames is the principle heat load to combustor components and is mainly responsible for engine durability problems of aircraft and gas turbine engines. As a result, there is considerable interest in controlling both soot concentrations within flames and soot emissions from flames. Thus, the objective of the present investigation is to study ways to control soot formation in diffusion flames by manipulating the mixing process between the fuel and oxidant streams. In order to prevent the intrusion of gravity from masking flow properties that reduce soot formation in practical flames (where effects of gravity are small), methods developed during past work will be exploited to minimize effects of buoyant motion.

  4. Estimating soot emissions from an elevated flare

    NASA Astrophysics Data System (ADS)

    Almanza, Victor; Sosa, Gustavo

    2009-11-01

    Combustion aerosols are one of the major concerns in flaring operations, due to both health and environmental hazards. Preliminary results are presented for a 2D transient simulation of soot formation in a reacting jet with exit velocity of 130 m/s under a 5 m/s crossflow released from a 50 m high elevated flare and a 50 cm nozzle. Combustion dynamics was simulated with OpenFOAM. Gas-phase non-premixed combustion was modeled with the Chalmers PaSR approach and a κ-ɛ turbulence model. For soot formation, Moss model was used and the ISAT algorithm for solving the chemistry. Sulfur chemistry was considered to account for the sourness of the fuel. Gas composition is 10 % H2S and 90 % C2H4. A simplified Glassman reaction mechanism was used for this purpose. Results show that soot levels are sensitive to the sulfur present in the fuel, since it was observed a slight decrease in the soot volume fraction. NSC is the current oxidation model for soot formation. Predicted temperature is high (about 2390 K), perhaps due to soot-radiation interaction is not considered yet, but a radiation model implementation is on progress, as well as an oxidation mechanism that accounts for OH radical. Flame length is about 50 m.

  5. Heterogeneous reaction of SO2 with soot: The roles of relative humidity and surface composition of soot in surface sulfate formation

    NASA Astrophysics Data System (ADS)

    Zhao, Yan; Liu, Yongchun; Ma, Jinzhu; Ma, Qingxin; He, Hong

    2017-03-01

    The conversion of SO2 to sulfates on the surface of soot is still poorly understood. Soot samples with different fractions of unsaturated hydrocarbons and oxygen-containing groups were prepared by combusting n-hexane under well-controlled conditions. The heterogeneous reaction of SO2 with soot was investigated using in situ attenuated total internal reflection infrared (ATR-IR) spectroscopy, ion chromatography (IC) and a flow tube reactor at the ambient pressure and relative humidity (RH). Water promoted SO2 adsorption and sulfate formation at the RH range from 6% to 70%, while exceeded water condensed on soot was unfavorable for sulfate formation due to inhibition of SO2 adsorption when RH was higher than 80%. The surface composition of soot, which was governed by combustion conditions, also played an important role in the heterogeneous reaction of SO2 with soot. This effect was found to greatly depend on RH. At low RH of 6%, soot with the highest fuel/oxygen ratio of 0.162 exhibited a maximum uptake capacity for SO2 because it contained a large amount of aromatic Csbnd H groups, which acted as active sites for SO2 adsorption. At RH of 54%, soot produced with a fuel/oxygen ratio of 0.134 showed the highest reactivity toward SO2 because it contained appropriate amounts of aromatic Csbnd H groups and oxygen-containing groups, subsequently leading to the optimal surface concentrations of both SO2 and water. These results suggest that variation in the surface composition of soot from different sources and/or resulting from chemical aging in the atmosphere likely affects the conversion of SO2 to sulfates.

  6. Structure and Early Soot Oxidation Properties of Laminar Diffusion Flames

    NASA Technical Reports Server (NTRS)

    El-Leathy, A. M.; Xu, F.; Faeth, G. M.

    2001-01-01

    Soot is an important unsolved problem of combustion science because it is present in most hydrocarbon-fueled flames and current understanding of the reactive and physical properties of soot in flame environments is limited. This lack of understanding affects progress toward developing reliable predictions of flame radiation properties, reliable predictions of flame pollutant emission properties and reliable methods of computational combustion, among others. Motivated by these observations, the present investigation extended past studies of soot formation in this laboratory, to consider soot oxidation in laminar diffusion flames using similar methods. Early work showed that O2 was responsible for soot oxidation in high temperature O2-rich environments. Subsequent work in high temperature flame environments having small O2 concentrations, however, showed that soot oxidation rates substantially exceeded estimates based on the classical O2 oxidation rates of Nagle and Strickland-Constable and suggests that radicals such as O and OH might be strong contributors to soot oxidation for such conditions. Neoh et al. subsequently made observations in premixed flames, supported by later work, that showed that OH was responsible for soot oxidation at these conditions with a very reasonable collision efficiency of 0.13. Subsequent studies in diffusion flames, however, were not in agreement with the premixed flame studies: they agreed that OH played a dominant role in soot oxidation in flames, but found collision efficiencies that varied with flame conditions and were not in good agreement with each other or with Neoh et al. One explanation for these discrepancies is that optical scattering and extinction properties were used to infer soot structure properties for the studies that have not been very successful for representing the optical properties of soot. Whatever the source of the problem, however, these differences among observations of soot oxidation in premixed and

  7. Large eddy simulation of soot evolution in an aircraft combustor

    NASA Astrophysics Data System (ADS)

    Mueller, Michael E.; Pitsch, Heinz

    2013-11-01

    An integrated kinetics-based Large Eddy Simulation (LES) approach for soot evolution in turbulent reacting flows is applied to the simulation of a Pratt & Whitney aircraft gas turbine combustor, and the results are analyzed to provide insights into the complex interactions of the hydrodynamics, mixing, chemistry, and soot. The integrated approach includes detailed models for soot, combustion, and the unresolved interactions between soot, chemistry, and turbulence. The soot model is based on the Hybrid Method of Moments and detailed descriptions of soot aggregates and the various physical and chemical processes governing their evolution. The detailed kinetics of jet fuel oxidation and soot precursor formation is described with the Radiation Flamelet/Progress Variable model, which has been modified to account for the removal of soot precursors from the gas-phase. The unclosed filtered quantities in the soot and combustion models, such as source terms, are closed with a novel presumed subfilter PDF approach that accounts for the high subfilter spatial intermittency of soot. For the combustor simulation, the integrated approach is combined with a Lagrangian parcel method for the liquid spray and state-of-the-art unstructured LES technology for complex geometries. Two overall fuel-to-air ratios are simulated to evaluate the ability of the model to make not only absolute predictions but also quantitative predictions of trends. The Pratt & Whitney combustor is a Rich-Quench-Lean combustor in which combustion first occurs in a fuel-rich primary zone characterized by a large recirculation zone. Dilution air is then added downstream of the recirculation zone, and combustion continues in a fuel-lean secondary zone. The simulations show that large quantities of soot are formed in the fuel-rich recirculation zone, and, furthermore, the overall fuel-to-air ratio dictates both the dominant soot growth process and the location of maximum soot volume fraction. At the higher fuel

  8. Candle Soot-Driven Performance Enhancement in Pyroelectric Energy Conversion

    NASA Astrophysics Data System (ADS)

    Azad, Puneet; Singh, V. P.; Vaish, Rahul

    2018-05-01

    We observed substantial enhancement in pyroelectric output with the help of candle soot coating on the surface of lead zirconate titanate (PZT). Candle soot of varying thicknesses was coated by directly exposing pyroelectric material to the candle flame. The open-circuit pyroelectric voltage and closed-circuit pyroelectric current were recorded while applying infrared heating across the uncoated and candle soot-coated samples for different heating and cooling cycles. In comparison to the uncoated sample, the maximum open-circuit voltage improves seven times for the candle soot-coated sample and electric current increases by eight times across a resistance of 10Å. Moreover, the harvested energy is enhanced by 50 times for candle soot-coated sample. Results indicate that candle soot coating is an effective and economic method to improve infrared sensing performance of pyroelectric materials.

  9. Computational Investigation of Soot and Radiation in Turbulent Reacting Flows

    NASA Astrophysics Data System (ADS)

    Lalit, Harshad

    This study delves into computational modeling of soot and infrared radiation for turbulent reacting flows, detailed understanding of both of which is paramount in the design of cleaner engines and pollution control. In the first part of the study, the concept of Stochastic Time and Space Series Analysis (STASS) as a numerical tool to compute time dependent statistics of radiation intensity is introduced for a turbulent premixed flame. In the absence of high fidelity codes for large eddy simulation or direct numerical simulation of turbulent flames, the utility of STASS for radiation imaging of reacting flows to understand the flame structure is assessed by generating images of infrared radiation in spectral bands dominated by radiation from gas phase carbon dioxide and water vapor using an assumed PDF method. The study elucidates the need for time dependent computation of radiation intensity for validation with experiments and the need for accounting for turbulence radiation interactions for correctly predicting radiation intensity and consequently the flame temperature and NOx in a reacting fluid flow. Comparison of single point statistics of infrared radiation intensity with measurements show that STASS can not only predict the flame structure but also estimate the dynamics of thermochemical scalars in the flame with reasonable accuracy. While a time series is used to generate realizations of thermochemical scalars in the first part of the study, in the second part, instantaneous realizations of resolved scale temperature, CO2 and H2O mole fractions and soot volume fractions are extracted from a large eddy simulation (LES) to carry out quantitative imaging of radiation intensity (QIRI) for a turbulent soot generating ethylene diffusion flame. A primary motivation of the study is to establish QIRI as a computational tool for validation of soot models, especially in the absence of conventional flow field and measured scalar data for sooting flames. Realizations of

  10. Revolutionary systems for catalytic combustion and diesel catalytic particulate traps.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Stuecker, John Nicholas; Witze, Peter O.; Ferrizz, Robert Matthew

    2004-12-01

    This report is a summary of an LDRD project completed for the development of materials and structures conducive to advancing the state of the art for catalyst supports and diesel particulate traps. An ancillary development for bio-medical bone scaffolding was also realized. Traditionally, a low-pressure drop catalyst support, such as a ceramic honeycomb monolith, is used for catalytic reactions that require high flow rates of gases at high-temperatures. A drawback to the traditional honeycomb monoliths under these operating conditions is poor mass transfer to the catalyst surface in the straight-through channels. ''Robocasting'' is a unique process developed at Sandia Nationalmore » Laboratories that can be used to manufacture ceramic monoliths with alternative 3-dimensional geometries, providing tortuous pathways to increase mass transfer while maintaining low-pressure drops. These alternative 3-dimensional geometries may also provide a foundation for the development of self-regenerating supports capable of trapping and combusting soot particles from a diesel engine exhaust stream. This report describes the structures developed and characterizes the improved catalytic performance that can result. The results show that, relative to honeycomb monolith supports, considerable improvement in mass transfer efficiency is observed for robocast samples synthesized using an FCC-like geometry of alternating rods. Also, there is clearly a trade-off between enhanced mass transfer and increased pressure drop, which can be optimized depending on the particular demands of a given application. Practical applications include the combustion of natural gas for power generation, production of syngas, and hydrogen reforming reactions. The robocast lattice structures also show practicality for diesel particulate trapping. Preliminary results for trapping efficiency are reported as well as the development of electrically resistive lattices that can regenerate the structure by

  11. Observations of urban airborne particle number concentrations during rush-hour conditions: analysis of the number based size distributions and modal parameters.

    PubMed

    Lingard, Justin J N; Agus, Emily L; Young, David T; Andrews, Gordon E; Tomlin, Alison S

    2006-12-01

    A summertime study of the number concentration and the size distribution of combustion derived nanometre sized particles (termed nanoparticles) from diesel and spark-ignition (SI) engine emissions were made under rush-hour and free-flow traffic conditions at an urban roadside location in Leeds, UK in July 2003. The measured total particle number concentrations (N(TOTAL)) were of the order 1.8 x 10(4) to 3.4 x 10(4) cm(-3), and tended to follow the diurnal traffic flow patterns. The N(TOTAL) was dominated by particles < or =100 nm in diameter which accounted for between 89-93% of the measured particle number. By use of a log-normal fitting procedure, the modal parameters of the number based particle size distribution of urban airborne particulates were derived from the roadside measurements. Four component modes were identified. Two nucleation modes were found, with a smaller, more minor, mode composed principally of sub-11 nm particles, believed to be derived from particles formed from the nucleation of gaseous species in the atmosphere. A second mode, much larger in terms of number, was composed of particles within the size range of 10-20 nm. This second mode was believed to be principally derived from the condensation of the unburned fuel and lube oil (the solvent organic fraction or SOF) as it cooled on leaving the engine exhaust. Third and fourth modes were noted within the size ranges of 28-65 nm and 100-160 nm, respectively. The third mode was believed to be representative of internally mixed Aitken mode particles composed of a soot/ash core with an adsorbed layer of readily volatilisable material. The fourth mode was believed to be composed of chemically aged, secondary particles. The larger nucleation and Aitken modes accounted for between 80-90% of the measured N(TOTAL), and the particles in these modes were believed to be derived from SI and diesel engine emissions. The overall size distribution, particularly in modes II-IV, was observed to be strongly

  12. Soot Formation in Laminar Acetylene/Air Diffusion Flames at Atmospheric Pressure. Appendix C

    NASA Technical Reports Server (NTRS)

    Xu, F.; Faeth, G. M.; Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

    2000-01-01

    The flame structure and soot-formation (soot nucleation and growth) properties of axisymmetric laminar coflowing jet diffusion flames were studied experimentally. Test conditions involved acetylene-nitrogen jets burning in coflowing air at atmospheric pressure. Measurements were limited to the axes of the flames and included soot concentrations, soot temperatures, soot structure, major gas species concentrations, radical species (H, OH, and O) concentrations, and gas velocities. The results show that as distance increases along the axes of the flames, detectable soot formation begins when significant H concentrations are present, and ends when acetylene concentrations become small. Species potentially associated with soot oxidation-O2, CO2, H2O, O, and OH-are present throughout the soot-formation region so that soot formation and oxidation proceed at the same time. Strong rates of soot growth compared to soot nucleation early in the soot-formation process, combined with increased rates of soot nucleation and oxidation as soot formation proceeds, causes primary soot particle diameters to reach a maximum relatively early in the soot-formation process. Aggregation of primary soot particles proceeds, however, until the final stages of soot oxidation. Present measurements of soot growth (corrected for soot oxidation) in laminar diffusion flames were consistent with earlier measurements of soot growth in laminar premixed flames and exhibited encouraging agreement with existing hydrogen-abstraction/carbon-addition (HACA) soot growth mechanisms in the literature that were developed based on measurements within laminar premixed flames. Measured primary soot particle nucleation rates in the present laminar diffusion flames also were consistent with corresponding rates measured in laminar premixed flames and yielded a crude correlation in terms of acetylene and H concentrations and the temperature.

  13. Soot Formation in Laminar Acetylene/Air Diffusion Flames at Atmospheric Pressure. Appendix H

    NASA Technical Reports Server (NTRS)

    Xu, F.; Faeth, G. M.; Yuan, Z.-G. (Technical Monitor); Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

    2001-01-01

    The flame structure and soot-formation (soot nucleation and growth) properties of axisymmetric laminar coflowing jet diffusion flames were studied experimentally. Test conditions involved acetylene-nitrogen jets burning in coflowing air at atmospheric pressure. Measurements were limited to the axes of the flames and included soot concentrations, soot temperatures, soot structure, major gas species concentrations, radical species (H, OH, and O) concentrations, and gas velocities. The results show that as distance increases along the axes of the flames, detectable soot formation begins when significant H concentrations are present, and ends when acetylene concentrations become small. Species potentially associated with soot oxidation-O2, CO2, H2O, O, and OH-are present throughout the soot-formation region so that soot formation and oxidation proceed at the same time. Strong rates of soot growth compared to soot nucleation early in the soot-formation process, combined with increased rates of soot nucleation and oxidation as soot formation proceeds, causes primary soot particle diameters to reach a maximum relatively early in the soot-formation process. Aggregation of primary soot particles proceeds, however, until the final stages of soot oxidation. Present measurements of soot growth (corrected for soot oxidation) in laminar diffusion flames were consistent with earlier measurements of soot growth in laminar premixed flames and exhibited encouraging agreement with existing hydrogen-abstraction/carbon-addition (HACA) soot growth mechanisms in the literature that were developed based on measurements within laminar premixed flames. Measured primary soot particle nucleation rates in the present laminar diffusion flames also were consistent with corresponding rates measured in laminar premixed flames and yielded a crude correlation in terms of acetylene and H concentrations and the temperature.

  14. Soot Formation in Laminar Acetylene/Air Diffusion Flames at Atmospheric Pressure. Appendix J

    NASA Technical Reports Server (NTRS)

    Xu, F.; Faeth, G. M.; Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

    2001-01-01

    The flame structure and soot-formation (soot nucleation and growth) properties of axisymmetric laminar coflowing jet diffusion flames were studied experimentally. Test conditions involved acetylene-nitrogen jets burning in coflowing air at atmospheric pressure. Measurements were limited to the axes of the flames and included soot concentrations, soot temperatures, soot structure, major gas species concentrations, radical species (H, OH, and O) concentrations, and gas velocities. The results show that as distance increases along the axes of the flames, detectable soot formation begins when significant H concentrations are present, and ends when acetylene concentrations become small. Species potentially associated with soot oxidation--O2, CO2, H2O, O, and OH-are present throughout the soot-formation region so that soot formation and oxidation proceed at the same time. Strong rates of soot growth compared to soot nucleation early in the soot-formation process, combined with increased rates of soot nucleation and oxidation as soot formation proceeds, causes primary soot particle diameters to reach a maximum relatively early in the soot-formation process. Aggregation of primary soot particles proceeds, however, until the final stages of soot oxidation. Present measurements of soot growth (corrected for soot oxidation) in laminar diffusion flames were consistent with earlier measurements of soot growth in laminar premixed flames and exhibited encouraging agreement with existing hydrogen-abstraction/carbon-addition (HACA) soot growth mechanisms in the literature that were developed based on measurements within laminar premixed flames. Measured primary soot particle nucleation rates in the present laminar diffusion flames also were consistent with corresponding rates measured in laminar premixed flames and yielded a crude correlation in terms of acetylene and H concentrations and the temperature.

  15. DIESEL EXHAUST ACTIVATES REDOX-SENSITIVE TRANSCRIPTION FACTORS AND KINASES IN HUMAN AIRWAYS

    EPA Science Inventory

    Diesel exhaust (DE) is a major component of airborne particulate matter. In previous studies we have described the acute inflammatory response of the human airway to inhaled DE. This was characterized by neutrophil, mast cell, and lymphocyte infiltration into the bronchial mucosa...

  16. Optical study on thermal radiation energy of diesel spray combustion in a shock tube

    NASA Astrophysics Data System (ADS)

    Tsuboi, T.; Nagaya, K.; Ishii, K.

    . A ``tailored'' interface shock tube was used to measure the thermal energy radiated from diesel-spray combustion. Experiments were performed in a steel shock tube with a seven m long low-pressure section filled with air and a six m long high-pressure section. Pre-compressed fuel was injected through a throttling nozzle into air behind a reflected shock wave. Monochromatic emissive powers and emissive powers of the whole IR-wavelengths were followed with IR-detectors set along the central axis of the tube. Time-dependent-radii, where soot particles radiate, were also determined. Results were : (1) the tailored interface shock tube could be applied to a study of diesel-spray combustion. (2) thermal radiation energy could be described well from the ignition delay of the fuel spray.

  17. Soot loading in a generic gas turbine combustor

    NASA Technical Reports Server (NTRS)

    Eckerle, W. A.; Rosfjord, T. J.

    1987-01-01

    Variation in soot loading along the centerline of a generic gas turbine combustor was experimentally investigated. The 12.7-cm dia burner consisted of six sheet-metal louvers. Soot loading along the burner length was quantified by acquiring measurements first at the exit of the full-length combustor and then at upstream stations by sequential removal of liner louvers to shorten the burner length. Alteration of the flow field approaching removed louvers, maintaining a constant liner pressure drop. Burner exhaust flow was sampled at the burner centerline to determine soot mass concentration and smoke number. Characteristic particle size and number density, transmissivity of the exhaust flow, and local radiation from luminous soot particles in the exhaust flow were determined by optical techniques. Four test fuels were burned at three fuel-air ratios to determine fuel chemical property and flow temperature influences. Data were acquired at two combustor pressures. Particulate concentration data indicated a strong oxidation mechanism in the combustor secondary zone, though the oxidation was significantly affected by flow temperature. Soot production was directly related to fuel smoke point. Less soot production and lower secondary-zone oxidation rates were observed at reduced combustor pressure.

  18. Durable superhydrophobic carbon soot coatings for sensor applications

    NASA Astrophysics Data System (ADS)

    Esmeryan, K. D.; Radeva, E. I.; Avramov, I. D.

    2016-01-01

    A novel approach for the fabrication of durable superhydrophobic (SH) carbon soot coatings used in quartz crystal microbalance (QCM) based gas or liquid sensors is reported. The method uses modification of the carbon soot through polymerization of hexamethyldisiloxane (HMDSO) by means of glow discharge RF plasma. The surface characterization shows a fractal-like network of carbon nanoparticles with diameter of ~50 nm. These particles form islands and cavities in the nanometer range, between which the plasma polymerized hexamethyldisiloxane (PPHMDSO) embeds and binds to the carbon chains and QCM surface. Such modified surface structure retains the hydrophobic nature of the soot and enhances its robustness upon water droplet interactions. Moreover, it significantly reduces the insertion loss and dynamic resistance of the QCM compared to the commonly used carbon soot/epoxy resin approach. Furthermore, the PPHMDSO/carbon soot coating demonstrates durability and no aging after more than 40 probing cycles in water based liquid environments. In addition, the surface layer keeps its superhydrophobicity even upon thermal annealing up to 540 °C. These experiments reveal an opportunity for the development of soot based SH QCMs with improved electrical characteristics, as required for high-resolution gas or liquid measurements.

  19. 30 CFR 57.5060 - Limit on exposure to diesel particulate matter.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... diesel particulate matter (DPM) in an underground mine must not exceed an average eight-hour equivalent... particulate matter (DPM) in an underground mine must not exceed an average eight-hour equivalent full shift... mine must not exceed an average eight-hour equivalent full shift airborne concentration of 350...

  20. 30 CFR 57.5060 - Limit on exposure to diesel particulate matter.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... diesel particulate matter (DPM) in an underground mine must not exceed an average eight-hour equivalent... particulate matter (DPM) in an underground mine must not exceed an average eight-hour equivalent full shift... mine must not exceed an average eight-hour equivalent full shift airborne concentration of 350...

  1. 30 CFR 57.5060 - Limit on exposure to diesel particulate matter.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... diesel particulate matter (DPM) in an underground mine must not exceed an average eight-hour equivalent... particulate matter (DPM) in an underground mine must not exceed an average eight-hour equivalent full shift... mine must not exceed an average eight-hour equivalent full shift airborne concentration of 350...

  2. 30 CFR 57.5060 - Limit on exposure to diesel particulate matter.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... diesel particulate matter (DPM) in an underground mine must not exceed an average eight-hour equivalent... particulate matter (DPM) in an underground mine must not exceed an average eight-hour equivalent full shift... mine must not exceed an average eight-hour equivalent full shift airborne concentration of 350...

  3. Diesel Exhaust Modulates Ozone-induced Lung Function Decrements in Healthy Human Volunteers

    EPA Science Inventory

    The potential effects of combinations of dilute whole diesel exhaust (DE) and ozone (03), each a common component of ambient airborne pollutant mixtures, on lung function were examined. Healthy young human volunteers were exposed for 2 hr to pollutants while exercising (~50 L/min...

  4. NASAL RESPONSES OF ASTHMATIC AND NON-ASTHMATIC VOLUNTEERS TO DIESEL EXHAUST PARTICLES

    EPA Science Inventory

    Asthma rates have been increasing world-wide, and exposure to diesel exhaust particles (DEP) may be implicated in this increase. Additionally DEP may also play a role in the increased morbidity and mortality associated with ambient airborne PM exposure. Two types of nasal respons...

  5. Spectroscopic and solubility characteristics of oxidized soots

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chughtai, A.R.; Jassim, J.A.; Peterson, J.H.

    1991-01-01

    Spectroscopic and solubility studies of reaction products of soot (black carbon) with O{sub 3}, NO{sub 2}/N{sub 2}O{sub 4}, and SO{sub 2} have revealed a relationship between reactivity and product solubility and structure. A remarkably high solubility of ozonated n-hexane soot has its origin in the formation of anhydride and lactone surface structures and their subsequent hydrolysis to carboxylic acid species. Calculations indicate that the rate of surface carboxylation of 0.1-{mu}m diameter spheroidal soot particles, in the presence of 50 ppbv ozone at ambient temperature, is such that solubilization may occur within a 30-minute time frame. Measurements on ambient air aerosolmore » samples in metropolitan Denver are consistent with these observations and demonstrate the high reactivity of soot with ozone even at very low levels in natural systems.« less

  6. Impaired vascular function after exposure to diesel exhaust generated at urban transient running conditions

    PubMed Central

    2010-01-01

    under ETC conditions was also associated with a novel finding of impaired of calcium channel-dependent vasomotor function. This implies that certain cardiovascular endpoints seem to be related to general diesel exhaust properties, whereas the novel calcium flux-related effect may be associated with exhaust properties more specific for the ETC condition, for example a higher content of diesel soot particles along with their adsorbed organic compounds. PMID:20653945

  7. Effects of mixing states on the multiple-scattering properties of soot aerosols.

    PubMed

    Cheng, Tianhai; Wu, Yu; Gu, Xingfa; Chen, Hao

    2015-04-20

    The radiative properties of soot aerosols are highly sensitive to the mixing states of black carbon particles and other aerosol components. Light absorption properties are enhanced by the mixing state of soot aerosols. Quantification of the effects of mixing states on the scattering properties of soot aerosol are still not completely resolved, especially for multiple-scattering properties. This study focuses on the effects of the mixing state on the multiple scattering of soot aerosols using the vector radiative transfer model. Two types of soot aerosols with different mixing states such as external mixture soot aerosols and internal mixture soot aerosols are studied. Upward radiance/polarization and hemispheric flux are studied with variable soot aerosol loadings for clear and haze scenarios. Our study showed dramatic changes in upward radiance/polarization due to the effects of the mixing state on the multiple scattering of soot aerosols. The relative difference in upward radiance due to the different mixing states can reach 16%, whereas the relative difference of upward polarization can reach 200%. The effects of the mixing state on the multiple-scattering properties of soot aerosols increase with increasing soot aerosol loading. The effects of the soot aerosol mixing state on upwelling hemispheric flux are much smaller than in upward radiance/polarization, which increase with increasing solar zenith angle. The relative difference in upwelling hemispheric flux due to the different soot aerosol mixing states can reach 18% when the solar zenith angle is 75°. The findings should improve our understanding of the effects of mixing states on the optical properties of soot aerosols and their effects on climate. The mixing mechanism of soot aerosols is of critical importance in evaluating the climate effects of soot aerosols, which should be explicitly included in radiative forcing models and aerosol remote sensing.

  8. Phospholipid lung surfactant and nanoparticle surface toxicity: Lessons from diesel soots and silicate dusts

    NASA Astrophysics Data System (ADS)

    Wallace, William E.; Keane, Michael J.; Murray, David K.; Chisholm, William P.; Maynard, Andrew D.; Ong, Tong-man

    2007-01-01

    Because of their small size, the specific surface areas of nanoparticulate materials (NP), described as particles having at least one dimension smaller than 100 nm, can be large compared with micrometer-sized respirable particles. This high specific surface area or nanostructural surface properties may affect NP toxicity in comparison with micrometer-sized respirable particles of the same overall composition. Respirable particles depositing on the deep lung surfaces of the respiratory bronchioles or alveoli will contact pulmonary surfactants in the surface hypophase. Diesel exhaust ultrafine particles and respirable silicate micrometer-sized insoluble particles can adsorb components of that surfactant onto the particle surfaces, conditioning the particles surfaces and affecting their in vitro expression of cytotoxicity or genotoxicity. Those effects can be particle surface composition-specific. Effects of particle surface conditioning by a primary component of phospholipid pulmonary surfactant, diacyl phosphatidyl choline, are reviewed for in vitro expression of genotoxicity by diesel exhaust particles and of cytotoxicity by respirable quartz and aluminosilicate kaolin clay particles. Those effects suggest methods and cautions for assaying and interpreting NP properties and biological activities.

  9. Soot blower using fuel gas as blowing medium

    DOEpatents

    Tanca, Michael C.

    1982-01-01

    A soot blower assembly (10) for use in combination with a coal gasifier (14). The soot blower assembly is adapted for use in the hot combustible product gas generated in the gasifier as the blowing medium. The soot blower lance (20) and the drive means (30) by which it is moved into and out of the gasifier is housed in a gas tight enclosure (40) which completely surrounds the combination. The interior of the enclosure (40) is pressurized by an inert gas to a pressure level higher than that present in the gasifier so that any combustible product gas leaking from the soot blower lance (20) is forced into the gasifier rather than accumulating within the enclosure.

  10. Series of Laminar Soot Processes Experiment

    NASA Technical Reports Server (NTRS)

    2003-01-01

    Study of the downlink data from the Laminar Soot Processes (LSP) experiment quickly resulted in discovery of a new mechanism of flame extinction caused by radiation of soot. Scientists found that the flames emit soot sooner than expected. These findings have direct impact on spacecraft fire safety, as well as the theories predicting the formation of soot -- which is a major factor as a pollutant and in the spread of unwanted fires. This sequence was taken July 15, 1997, MET:14/10:34 (approximate) and shows the ignition and extinction of this flame. LSP investigated fundamental questions regarding soot, a solid byproduct of the combustion of hydrocarbon fuels. The experiment was performed using a laminar jet diffusion flame, which is created by simply flowing fuel -- like ethylene or propane -- through a nozzle and igniting it, much like a butane cigarette lighter. The LSP principal investigator was Gerard Faeth, University of Michigan, Arn Arbor. The experiment was part of the space research investigations conducted during the Microgravity Science Laboratory-1R mission (STS-94, July 1-17 1997). LSP results led to a reflight for extended investigations on the STS-107 research mission in January 2003. Advanced combustion experiments will be a part of investigations planned for the International Space Station. (189KB JPEG, 1350 x 1517 pixels; downlinked video, higher quality not available) The MPG from which this composite was made is available at http://mix.msfc.nasa.gov/ABSTRACTS/MSFC-0300183.html.

  11. Measurements of ion concentration in gasoline and diesel engine exhaust

    NASA Astrophysics Data System (ADS)

    Yu, Fangqun; Lanni, Thomas; Frank, Brian P.

    The nanoparticles formed in motor vehicle exhaust have received increasing attention due to their potential adverse health effects. It has been recently proposed that combustion-generated ions may play a critical role in the formation of these volatile nanoparticles. In this paper, we design an experiment to measure the total ion concentration in motor vehicle engine exhaust, and report some preliminary measurements in the exhaust of a gasoline engine (K-car) and a diesel engine (diesel generator). Under the experimental set-up reported in this study and for the specific engines used, the total ion concentration is ca. 3.3×10 6 cm -3 with almost all of the ions smaller than 3 nm in the gasoline engine exhaust, and is above 2.7×10 8 cm -3 with most of the ions larger than 3 nm in the diesel engine exhaust. This difference in the measured ion properties is interpreted as a result of the different residence times of exhaust inside the tailpipe/connecting pipe and the different concentrations of soot particles in the exhaust. The measured ion concentrations appear to be within the ranges predicted by a theoretical model describing the evolution of ions inside a pipe.

  12. On the formation and early evolution of soot in turbulent nonpremixed flames

    NASA Astrophysics Data System (ADS)

    Bisetti, F.; Blanquart, G.; Mueller, M. E.; Pitsch, H.

    2010-11-01

    A direct numerical simulation of soot formation in a turbulent nonpremixed flame has been performed to investigate unsteady hydrodynamic strain effects on soot growth processes and transport immediately following nucleation. For the first time in a DNS, polycyclic aromatic hydrocarbon (PAH) species are included in the chemical kinetics mechanism to describe soot inception. A novel statistical representation of soot aggregates based on the Hybrid Method of Moments (HMOM) is employed. In agreement with previous experimental studies in laminar flames, Damköhler number effects are significant, and soot nucleation and growth are locally inhibited by high scalar dissipation rate. Upon formation on the rich side of the flame, soot is displaced relative to curved mixture fraction iso-surfaces due to differential diffusion effects. Soot traveling towards the flame is oxidized, and aggregates displaced away from the flame grow by condensation of PAH species on the surface of soot aggregates. In contrast to previous DNS studies employing simplified models, we find that soot-flame interaction plays a limited role in soot growth. Nucleation and condensation processes occurring in the fuel stream are responsible for the greatest generation of soot mass.

  13. Optical investigation of the combustion behaviour inside the engine operating in HCCI mode and using alternative diesel fuel

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mancaruso, E.; Vaglieco, B.M.

    2010-04-15

    In order to understand the effect of both the new homogeneous charge compression ignition (HCCI) combustion process and the use of biofuel, optical measurements were carried out into a transparent CR diesel engine. Rape seed methyl ester was used and tests with several injection pressures were performed. OH and HCO radical were detected and their evolutions were analyzed during the whole combustion. Moreover, soot concentration was measured by means the two colour pyrometry method. The reduction of particulate emission with biodiesel as compared to the diesel fuel was noted. Moreover, this effect resulted higher increasing the injection pressure. In themore » case of RME the oxidation of soot depends mainly from O{sub 2} content of fuel and OH is responsible of the NO formation in the chamber as it was observed for NO{sub x} exhaust emission. Moreover, it was investigated the evolution of HCO and CO into the cylinder. HCO was detected at the start of combustion. During the combustion, HCO oxidizes due to the increasing temperature and it produces CO. Both fuels have similar trend, the highest concentrations are detected for low injection pressure. This effect is more evident for the RME fuel. (author)« less

  14. Semitransparent ceramic heat-insulation of eco-friendly Low- Heat-Rejection diesel

    NASA Astrophysics Data System (ADS)

    Merzlikin, V. G.; Gutierrez, M. O.; Makarov, A. R.; Kostukov, A. V.; Dementev, A. A.; Khudyakov, S. V.; Zagumennov, F. A.

    2018-03-01

    Efficiency of diesel has been studied using well-known types of the ceramic heat-insulating HICs- or thermal barrier TBCs-coatings. This problem is relevant for a high-speed diesel combustion chamber in which an intensive radiant component (near IR) reaches ~50% within total thermal flux. Therefore, in their works the authors had been offering new concept of study these materials as semitransparent SHICs-, STBCs-coatings. On the Mie scattering theory, the effect of selection of the specific structural composition and porosity of coatings on the variation of their optical parameters is considered. Conducted spectrophotometric modeling of the volume-absorbed radiant energy by the coating had determined their acceptable temperature field. For rig testings, a coated piston using selected SHIC (PSZ-ceramic ZrO2+8%Y2O3) with a calculated optimum temperature gradient was chosen. A single cylinder experimental tractor diesel was used. At rotation frequency n > 2800 rpm, the heat losses were no more than 0.2 MW/m2. Executed testings showed ~2-3% lower specific fuel consumption in contrast to the diesel with an uncoated piston. Effective power and drive torque were ∼2-5% greater. The authors have substantiated the growth the efficiency of this Low-Heat-Rejection(LHR) diesel due to the known effect of soot deposition gasification at high speed. Then unpolluted semitransparent ceramic thermal insulation forms the required thermoradiation fields and temperature profiles and can affect regulation of heat losses and a reduction of primarily nitrogen dioxide generation.

  15. Diesel-Enriched Particulate Matter Functionally Activates Human Dendritic Cells

    PubMed Central

    Porter, Michael; Karp, Matthew; Killedar, Smruti; Bauer, Stephen M.; Guo, Jia; Williams, D'Ann; Breysse, Patrick; Georas, Steve N.; Williams, Marc A.

    2007-01-01

    Epidemiologic studies have associated exposure to airborne particulate matter (PM) with exacerbations of asthma. It is unknown how different sources of PM affect innate immunity. We sought to determine how car- and diesel exhaust–derived PM affects dendritic cell (DC) activation. DC development was modeled using CD34+ hematopoietic progenitors. Airborne PM was collected from exhaust plenums of Fort McHenry Tunnel providing car-enriched particles (CEP) and diesel-enriched particles (DEP). DC were stimulated for 48 hours with CEP, DEP, CD40-ligand, or lipopolysaccharide. DC activation was assessed by flow cytometry, enzyme-linked immunosorbent assay, and standard culture techniques. DEP increased uptake of fluorescein isothiocyanate–dextran (a model antigen) by DC. Diesel particles enhanced cell-surface expression of co-stimulatory molecules (e.g., CD40 [P < 0.01] and MHC class II [P < 0.01]). By contrast, CEP poorly affected antigen uptake and expression of cell surface molecules, and did not greatly affect cytokine secretion by DC. However, DEP increased production of TNF, IL-6, and IFN-γ (P < 0.01), IL-12 (P < 0.05), and vascular endothelial growth factor (P < 0.001). In co-stimulation assays of PM-exposed DC and alloreactive CD4+ T cells, both CEP and DEP directed a Th2-like pattern of cytokine production (e.g., enhanced IL-13 and IL-18 and suppressed IFN-γ production). CD4+ T cells were not functionally activated on exposure to either DEP or CEP. Car- and diesel-enriched particles exert a differential effect on DC activation. Our data support the hypothesis that DEP (and to a lesser extent CEP) regulate important functional aspects of human DC, supporting an adjuvant role for this material. PMID:17630318

  16. Droplet Combustion and Soot Formation in Microgravity

    NASA Technical Reports Server (NTRS)

    Avedisian, C. Thomas

    1994-01-01

    One of the most complex processes involved in the combustion ot liquid fuels is the formation of soot. A well characterized flow field and simplified flame structure can improve considerably the understanding of soot formation processes. The simplest flame shape to analyze for a droplet is spherical with its associated one-dimensional flow field. It is a fundamental limit and the oldest and most often analyzed configuration of droplet combustion. Spherical symmetry in the droplet burning process will arise when there is no relative motion between the droplet and ambience or uneven heating around the droplet periphery, and buoyancy effects are negligible. The flame and droplet are then concentric with each other and there is no liquid circulation within the droplet. An understanding of the effect of soot on droplet combustion should therefore benefit from this simplified configuration. Soot formed during spherically symmetric droplet combustion, however, has only recently drawn attention and it appears to be one of the few aspects associated with droplet combustion which have not yet been thoroughly investigated. For this review, the broad subject of droplet combustion is narrowed considerably by restricting attention specifically to soot combined with spherically symmetric droplet burning processes that are promoted.

  17. Kinetics and mechanism of soot formation in hydrocarbon combustion

    NASA Technical Reports Server (NTRS)

    Frenklach, Michael

    1990-01-01

    The focus of this work was on kinetic modeling. The specific objectives were: detailed modeling of soot formation in premixed flames, elucidation of the effects of fuel structure on the pathway to soot, and the development of a numerical technique for accurate modeling of soot particle coagulation and surface growth. Those tasks were successfully completed and are briefly summarized.

  18. Small particles big effect? - Investigating ice nucleation abilities of soot particles

    NASA Astrophysics Data System (ADS)

    Mahrt, Fabian; David, Robert O.; Lohmann, Ulrike; Stopford, Chris; Wu, Zhijun; Kanji, Zamin A.

    2017-04-01

    Atmospheric soot particles are primary particles produced by incomplete combustion of biomass and/or fossil fuels. Thus soot mainly originates from anthropogenic emissions, stemming from combustion related processes in transport vehicles, industrial and residential uses. Such soot particles are generally complex mixtures of black carbon (BC) and organic matter (OM) (Bond et al., 2013; Petzold et al., 2013), depending on the sources and the interaction of the primary particles with other atmospheric matter and/or gases BC absorbs solar radiation having a warming effect on global climate. It can also act as a heterogeneous ice nucleating particle (INP) and thus impact cloud-radiation interactions, potentially cooling the climate (Lohmann, 2002). Previous studies, however, have shown conflicting results concerning the ice nucleation ability of soot, limiting the ability to predict its effects on Earth's radiation budget. Here we present a laboratory study where we systematically investigate the ice nucleation behavior of different soot particles. Commercial soot samples are used, including an amorphous, industrial carbon frequently used in coatings and coloring (FW 200, Orion Engineered Carbons) and a fullerene soot (572497 ALDRICH), e.g. used as catalyst. In addition, we use soot generated from a propane flame Combustion Aerosol Standard Generator (miniCAST, JING AG), as a proxy for atmospheric soot particles. The ice nucleation ability of these soot types is tested on size-selected particles for a wide temperature range from 253 K to 218 K, using the Horizontal Ice Nucleation Chamber (HINC), a Continuous Flow Diffusion Chamber (CFDC) (Kanji and Abbatt, 2009). Ice nucleation results from these soot surrogates will be compared to chemically more complex real world samples, collected on filters. Filters will be collected during the 2016/2017 winter haze periods in Beijing, China and represent atmospheric soot particles with sources from both industrial and residential

  19. NASAL RESPONSES IN ASTHMATIC AND NONASTHMATIC SUBJECTS FOLLOWING EXPOSURE TO DIESEL EXHAUST PARTICLES

    EPA Science Inventory

    Asthma rates have been increasing world-wide, and exposure to diesel exhaust particles may be implicated in this increase. Additionally DEP may also play a role in the increased morbidity and mortality associated with ambient airborne PM exposure. Two types of nasal responses hav...

  20. Three-dimensional modeling of diesel engine intake flow, combustion and emissions-2

    NASA Technical Reports Server (NTRS)

    Reitz, R. D.; Rutland, C. J.

    1993-01-01

    A three-dimensional computer code, KIVA, is being modified to include state-of-the-art submodels for diesel engine flow and combustion. Improved and/or new submodels which have already been implemented and previously reported are: wall heat transfer with unsteadiness and compressibility, laminar-turbulent characteristic time combustion with unburned HC and Zeldo'vich NO(x), and spray/wall impingement with rebounding and sliding drops. Progress on the implementation of improved spray drop drag and drop breakup models, the formulation and testing of a multistep kinetics ignition model, and preliminary soot modeling results are described. In addition, the use of a block structured version of KIVA to model the intake flow process is described. A grid generation scheme was developed for modeling realistic (complex) engine geometries, and computations were made of intake flow in the ports and combustion chamber of a two-intake-value engine. The research also involves the use of the code to assess the effects of subprocesses on diesel engine performance. The accuracy of the predictions is being tested by comparisons with engine experiments. To date, comparisons were made with measured engine cylinder pressure, temperature and heat flux data, and the model results are in good agreement with the experiments. Work is in progress that will allow validation of in-cylinder flow and soot formation predictions. An engine test facility is described that is being used to provide the needed validation data. Test results were obtained showing the effect of injection rate and split injections on engine performance and emissions.

  1. An Experimental Investigation of the Laminar Flamelet Concept for Soot Properties

    NASA Technical Reports Server (NTRS)

    Diez, F. J.; Aalburg, C.; Sunderland, P. B.; Urban, D. L.; Yuan, Z.-G.; Faeth, G. M.

    2007-01-01

    The soot properties of round, nonbuoyant, laminar jet diffusion flames are described, based on experiments at microgravity carried out on orbit during three flights of the Space Shuttle Columbia, (Flights STS-83, 94 and 107). Experimental conditions included ethylene- and propane-fueled flames burning in still air at an ambient temperature of 300 K and ambient pressures of 35-100 kPa. Measurements included soot volume fraction distributions using deconvoluted laser extinction imaging, and soot temperature distributions using deconvoluted multiline emission imaging. Flowfield modeling based on the work of Spalding is presented. The present work explores whether soot properties of these flames are universal functions of mixture fraction, i.e., whether they satisfy soot state relationships. Measurements are presented, including radiative emissions and distributions of soot temperature and soot volume fraction. It is shown that most of the volume of these flames is bounded by the dividing streamline and thus should follow residence time state relationships. Most streamlines from the fuel supply to the surroundings are found to exhibit nearly the same maximum soot volume fraction and temperature. The radiation intensity along internal streamlines also is found to have relatively uniform values. Finally, soot state relationships were observed, i.e., soot volume fraction was found to correlate with estimated mixture fraction for each fuel/pressure selection. These results support the existence of soot property state relationships for steady nonbuoyant laminar diffusion flames, and thus in a large class of practical turbulent diffusion flames through the application of the laminar flamelet concept.

  2. Understanding and predicting soot generation in turbulent non-premixed jet flames.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Hai; Kook, Sanghoon; Doom, Jeffrey

    2010-10-01

    This report documents the results of a project funded by DoD's Strategic Environmental Research and Development Program (SERDP) on the science behind development of predictive models for soot emission from gas turbine engines. Measurements of soot formation were performed in laminar flat premixed flames and turbulent non-premixed jet flames at 1 atm pressure and in turbulent liquid spray flames under representative conditions for takeoff in a gas turbine engine. The laminar flames and open jet flames used both ethylene and a prevaporized JP-8 surrogate fuel composed of n-dodecane and m-xylene. The pressurized turbulent jet flame measurements used the JP-8 surrogatemore » fuel and compared its combustion and sooting characteristics to a world-average JP-8 fuel sample. The pressurized jet flame measurements demonstrated that the surrogate was representative of JP-8, with a somewhat higher tendency to soot formation. The premixed flame measurements revealed that flame temperature has a strong impact on the rate of soot nucleation and particle coagulation, but little sensitivity in the overall trends was found with different fuels. An extensive array of non-intrusive optical and laser-based measurements was performed in turbulent non-premixed jet flames established on specially designed piloted burners. Soot concentration data was collected throughout the flames, together with instantaneous images showing the relationship between soot and the OH radical and soot and PAH. A detailed chemical kinetic mechanism for ethylene combustion, including fuel-rich chemistry and benzene formation steps, was compiled, validated, and reduced. The reduced ethylene mechanism was incorporated into a high-fidelity LES code, together with a moment-based soot model and models for thermal radiation, to evaluate the ability of the chemistry and soot models to predict soot formation in the jet diffusion flame. The LES results highlight the importance of including an optically

  3. The effect of soot modeling on thermal radiation in buoyant turbulent diffusion flames

    NASA Astrophysics Data System (ADS)

    Snegirev, A.; Kokovina, E.; Tsoy, A.; Harris, J.; Wu, T.

    2016-09-01

    Radiative impact of buoyant turbulent diffusion flames is the driving force in fire development. Radiation emission and re-absorption is controlled by gaseous combustion products, mainly CO2 and H2O, and by soot. Relative contribution of gas and soot radiation depends on the fuel sooting propensity and on soot distribution in the flame. Soot modeling approaches incorporated in big commercial codes were developed and calibrated for momentum-dominated jet flames, and these approaches must be re-evaluated when applied to the buoyant flames occurring in fires. The purpose of this work is to evaluate the effect of the soot models available in ANSYS FLUENT on the predictions of the radiative fluxes produced by the buoyant turbulent diffusion flames with considerably different soot yields. By means of large eddy simulations, we assess capability of the Moss-Brooks soot formation model combined with two soot oxidation submodels to predict methane- and heptane-fuelled fires, for which radiative flux measurements are available in the literature. We demonstrate that the soot oxidation models could be equally important as soot formation ones to predict the soot yield in the overfire region. Contribution of soot in the radiation emission by the flame is also examined, and predicted radiative fluxes are compared to published experimental data.

  4. Effects of particulate oxidation catalyst on unregulated pollutant emission and toxicity characteristics from heavy-duty diesel engine.

    PubMed

    Feng, Xiangyu; Ge, Yunshan; Ma, Chaochen; Tan, Jianwei

    2015-01-01

    To evaluate the effects of particulate oxidation catalyst (POC) on unregulated pollutant emission and toxicity characteristics, polycyclic aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs), soot, soluble organic fractions (SOF) and sulphate emissions emitted from a heavy-duty diesel engine retrofitted with a POC were investigated on a diesel bench. The particulate matter (PM) in the exhaust was collected by Teflon membrane, and the PAHs and VOCs were analysed by a gas chromatography/mass spectrometer (GC/MS). The results indicate that the POC exhibits good performance on the emission control of VOCs, PAHs and PM. The POC and the diesel particulate filters (DPF) both show a good performance on reducing the VOCs emission. Though the brake-specific emission (BSE) reductions of the total PAHs by the POC were lower than those by the DPF, the POC still removed almost more than 50% of the total PAHs emission. After the engine was retrofitted with the POC, the reductions of the PM mass, SOF and soot emissions were 45.2-89.0%, 7.8-97.7% and 41.7-93.3%, respectively. The sulphate emissions decreased at low and medium loads, whereas at high load, the results were contrary. The PAHs emissions were decreased by 32.4-69.1%, and the contributions of the PAH compounds were affected by the POC, as well as by load level. The benzo[a]pyrene equivalent (BaPeq) of PAHs emissions were reduced by 35.9-97.6% with the POC. The VOCs emissions were reduced by 21.8-94.1% with the POC, and the reduction was more evident under high load.

  5. Radiative Heat Transfer modelling in a Heavy-Duty Diesel Engine

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Paul, Chandan; Sircar, Arpan; Ferreyro-Fernandez, Sebastian

    Detailed radiation modelling in piston engines has received relatively little attention to date. Recently, it is being revisited in light of current trends towards higher operating pressures and higher levels of exhaust-gas recirculation, both of which enhance molecular gas radiation. Advanced high-efficiency engines also are expected to function closer to the limits of stable operation, where even small perturbations to the energy balance can have a large influence on system behavior. Here several different spectral radiation property models and radiative transfer equation (RTE) solvers have been implemented in an OpenFOAM-based engine CFD code, and simulations have been performed for amore » heavy-duty diesel engine. Differences in computed temperature fields, NO and soot levels, and wall heat transfer rates are shown for different combinations of spectral models and RTE solvers. The relative importance of molecular gas radiation versus soot radiation is examined. And the influence of turbulence-radiation interactions is determined by comparing results obtained using local mean values of composition and temperature to compute radiative emission and absorption with those obtained using a particle-based transported probability density function method.« less

  6. Characterization of soot properties in two-meter JP-8 pool fires.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Suo-Anttila, Jill Marie; Jensen, Kirk A.; Blevins, Linda Gail

    2005-02-01

    The thermal hazard posed by large hydrocarbon fires is dominated by the radiative emission from high temperature soot. Since the optical properties of soot, especially in the infrared region of the electromagnetic spectrum, as well as its morphological properties, are not well known, efforts are underway to characterize these properties. Measurements of these soot properties in large fires are important for heat transfer calculations, for interpretation of laser-based diagnostics, and for developing soot property models for fire field models. This research uses extractive measurement diagnostics to characterize soot optical properties, morphology, and composition in 2 m pool fires. For measurementmore » of the extinction coefficient, soot extracted from the flame zone is transported to a transmission cell where measurements are made using both visible and infrared lasers. Soot morphological properties are obtained by analysis via transmission electron microscopy of soot samples obtained thermophoretically within the flame zone, in the overfire region, and in the transmission cell. Soot composition, including carbon-to-hydrogen ratio and polycyclic aromatic hydrocarbon concentration, is obtained by analysis of soot collected on filters. Average dimensionless extinction coefficients of 8.4 {+-} 1.2 at 635 nm and 8.7 {+-} 1.1 at 1310 nm agree well with recent measurements in the overfire region of JP-8 and other fuels in lab-scale burners and fires. Average soot primary particle diameters, radius of gyration, and fractal dimensions agree with these recent studies. Rayleigh-Debye-Gans theory of scattering applied to the measured fractal parameters shows qualitative agreement with the trends in measured dimensionless extinction coefficients. Results of the density and chemistry are detailed in the report.« less

  7. Laser-induced incandescence measurements of soot in turbulent pool fires.

    PubMed

    Frederickson, Kraig; Kearney, Sean P; Grasser, Thomas W

    2011-02-01

    We present what we believe to be the first application of the laser-induced incandescence (LII) technique to large-scale fire testing. The construction of an LII instrument for fire measurements is presented in detail. Soot volume fraction imaging from 2 m diameter pool fires burning blended toluene/methanol liquid fuels is demonstrated along with a detailed report of measurement uncertainty in the challenging pool fire environment. Our LII instrument relies upon remotely located laser, optical, and detection systems and the insertion of water-cooled, fiber-bundle-coupled collection optics into the fire plume. Calibration of the instrument was performed using an ethylene/air laminar diffusion flame produced by a Santoro-type burner, which allowed for the extraction of absolute soot volume fractions from the LII images. Single-laser-shot two-dimensional images of the soot layer structure are presented with very high volumetric spatial resolution of the order of 10(-5) cm3. Probability density functions of the soot volume fraction fluctuations are constructed from the large LII image ensembles. The results illustrate a highly intermittent soot fluctuation field with potentially large macroscale soot structures and clipped soot probability densities.

  8. The Role of Biogenic and Anthropogenic Hydrocarbons in Aging of Atmospheric Soot

    NASA Astrophysics Data System (ADS)

    Khalizov, A. F.; Qiu, C.; Lin, Y.; Ma, Y.; Wang, L.; Zhang, R.

    2012-12-01

    Atmospheric soot is often found to be internally mixed with other aerosol constituents, yet the processes responsible for the soot aging are not well understood. We have conducted a systematic study on the role of several representative biogenic and anthropogenic volatile organic compounds (VOCs), including monoterpenes and aromatics, in atmospheric aging of combustion soot. Aging experiments were conducted in a fluoropolymer chamber on size-classified soot aerosols in the presence of a VOC and an oxidant, either ozone or photolytically generated hydroxyl radical (OH). The evolution in the aging state of soot was monitored from measurements of the particle mobility size and mass, which were used to derive information about particle effective density, dynamic shape factor, and coating thickness. When exposed to VOC and oxidant, soot particles promptly gain mass due to condensation of low-volatility and partitioning of semi-volatile VOC oxidation products. Depending on the VOC, the increase in the particle mass is accompanied by an increase or a decrease in the particle mobility diameter. In either case, the effective density of coated soot particles increases during aging because the condensed material fills in the voids of fractal soot aggregates, forcing their restructuring. The latter is confirmed by thermal denuding experiments, which show an increase in the effective density for soot that was first aged and then heated to remove the coating from the soot core. Hygroscopic and optical properties of soot are significantly altered by aging. Upon humidification, the coating absorbs water, increasing in volume and causing an additional restructuring of soot aggregates. Coated particles are sufficiently hygroscopic to activate to cloud droplets at atmospherically relevant water supersaturations. Aged soot shows stronger light absorption and scattering, with an enhancement magnitude depending on the coating thickness and nature of the coating precursor. The rate of

  9. Aging of Diesel and Wood Burning Emissions in Smogchamber Experiments

    NASA Astrophysics Data System (ADS)

    Prevot, Andre S. H.

    2010-05-01

    Photochemical aging experiments were performed for emissions of a diesel passenger car and logwood-burner at the smogchamber at the Paul Scherrer Institute in Switzerland. The measurements include black carbon measurements (with Aethalometer, Multi-Angle Absorption Photometer, Single Particle Soot Photometer (SP-2), and Photoacoustic Spectrometer), organic mass measurements with the Aerodyne high-resolution Aerosol mass spectrometer and off-line GC-MS measurements. Single particle composition was measured with the TSI-Aerosol time-of-flight mass spectrometer. The size distribution is characterized with a scanning mobility particle sizer, and the hygroscopicity with a hygroscopicity tandem differential mobility analyzer. The given overview of the results of experiments during the last 1.5 years will focus on the formation secondary organic aerosol and include the oxidation of primary organic aerosols and the change of optical and hygroscopic properties. A considerable variability of most results is found for different after treatment systems of diesel cars and for different burning conditions of the log-wood burner which will be discussed in detail.

  10. A NOVEL TECHNIQUE FOR QUANTITATIVE ESTIMATION OF UPTAKE OF DIESEL EXHAUST PARTICLES BY LUNG CELLS

    EPA Science Inventory

    While airborne particulates like diesel exhaust particulates (DEP) exert significant toxicological effects on lungs, quantitative estimation of accumulation of DEP inside lung cells has not been reported due to a lack of an accurate and quantitative technique for this purpose. I...

  11. Soot Formation in Laminar Premixed Methane/Oxygen Flames at Atmospheric Pressure

    NASA Technical Reports Server (NTRS)

    Xu, F.; Lin, K.-C.; Faeth, G. M.

    1998-01-01

    Flame structure and soot formation were studied within soot-containing laminar premixed mc1hane/oxygen flames at atmospheric pressure. The following measurements were made: soot volume fractions by laser extinction, soot temperatures by multiline emission, gas temperatures (where soot was absent) by corrected fine-wire thermocouples, soot structure by thermophoretic sampling and transmission electron microscope (TEM), major gas species concentrations by sampling and gas chromatography, and gas velocities by laser velocimetry. Present measurements of gas species concentrations were in reasonably good agreement with earlier measurements due to Ramer et al. as well as predictions based on the detailed mechanisms of Frenklach and co-workers and Leung and Lindstedt: the predictions also suggest that H atom concentrations are in local thermodynamic equilibrium throughout the soot formation region. Using this information, it was found that measured soot surface growth rates could be correlated successfully by predictions based on the hydrogen-abstraction/carbon-addition (HACA) mechanisms of both Frenklach and co-workers and Colket and Hall, extending an earlier assessment of these mechanisms for premixed ethylene/air flames to conditions having larger H/C ratios and acetylene concentrations. Measured primary soot particle nucleation rates were somewhat lower than the earlier observations for laminar premixed ethylene/air flames and were significantly lower than corresponding rates in laminar diffusion flames. for reasons that still must be explained.

  12. Determination of kinetic data for soot oxidation: Modeling of competition between oxygen diffusion and reaction during thermogravimetric analysis

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gilot, P.; Bonnefoy, F.; Marcuccilli, F.

    1993-10-01

    Kinetic data concerning carbon black oxidation in the temperature range between 600 and 900 C have been obtained using thermogravimetric analysis. Modeling of diffusion in a boundary layer above the pan and inside the porous medium coupled to oxygen reaction with carbon black is necessary to obtain kinetic constants as a function of temperature. These calculations require the knowledge of the oxidation rate at a given constant temperature as a function of the initial mass loading m[sub o]. This oxidation rate, expressed in milligrams of soot consumed per second and per milligram of initial soot loading, decreases when m[sub o]more » increases, in agreement with a reaction in an intermediary regime where the kinetics and the oxygen diffusion operate. The equivalent diffusivity of oxygen inside the porous medium is evaluated assuming two degrees of porosity: between soot aggregates and inside each aggregate. Below 700 C an activation energy of about 103 kJ/mol can be related to a combustion reaction probably kinetically controlled. Beyond 700 C the activation energy of about 20 kJ/ mol corresponds to a reaction essentially controlled by oxygen diffusion leading to a constant density oxidation with oxygen consumption at or near the particle surface. To validate these data, they are used in the modeling of a Diesel particulate trap regeneration. In this particular case, the oxidizing flux is forced across the carbon black deposit, oxygen diffusion being insignificant. A good agreement between experimental results and model predictions is obtained, proving the rate constants validity.« less

  13. [Catalytic performance of Ce/Zr series catalysts on soot combustion].

    PubMed

    Zhu, Ling; Wang, Xue-Zhong; Hao, Zheng-Ping

    2005-09-01

    Catalytic performances of Ce/Zr series catalysts (Ce(x)Zr(1-x)O2) on soot combustion and the influence of feed gas were investigated by TG and TPO. The catalytic activity is high, and affects by the Ce/Zr ratio. The concentration of O2 affects the speed-limited step during the process of soot combustion. H2O showed no effect on the catalytic activity for soot combustion on Ce(0.5)Zr(0.5)O2. NO could promote soot combustion by presenting NO2, a more powerful oxidant than O2, and the ignition temperature of soot decreased 30 degrees C. Results of TG and TPO show that the beta species oxygen on the catalyst take part in the combustion process.

  14. Brief Communication: Buoyancy-Induced Differences in Soot Morphology

    NASA Technical Reports Server (NTRS)

    Ku, Jerry C.; Griffin, Devon W.; Greenberg, Paul S.; Roma, John

    1995-01-01

    Reduction or elimination of buoyancy in flames affects the dominant mechanisms driving heat transfer, burning rates and flame shape. The absence of buoyancy produces longer residence times for soot formation, clustering and oxidation. In addition, soot pathlines are strongly affected in microgravity. We recently conducted the first experiments comparing soot morphology in normal and reduced-gravity laminar gas jet diffusion flames. Thermophoretic sampling is a relatively new but well-established technique for studying the morphology of soot primaries and aggregates. Although there have been some questions about biasing that may be induced due to sampling, recent analysis by Rosner et al. showed that the sample is not biased when the system under study is operating in the continuum limit. Furthermore, even if the sampling is preferentially biased to larger aggregates, the size-invariant premise of fractal analysis should produce a correct fractal dimension.

  15. Laminar Soot Processes (Lsp) Experiment: Findings From Ground-Based Measurements

    NASA Technical Reports Server (NTRS)

    Kim, C. H.; El-Leathy, A. M.; Faeth, G. M.; Xu, F.

    2003-01-01

    Processes of soot formation and oxidation must be understood in order to achieve reliable computational combustion calculations for nonpremixed (diffusion) flames involving hydrocarbon fuels. Motivated by this observation, the present investigation extended earlier work on soot formation and oxidation in laminar jet ethylene/air and methane/oxygen premixed and acetylene-nitrogen/air diffusion flames at atmospheric pressure in this laboratory, emphasizing soot surface growth and early soot surface oxidation in laminar diffusion flames fueled with a variety of hydrocarbons at pressures in the range 0.1 - 1.0 atm.

  16. Asbestos exposure from gaskets during disassembly of a medium duty diesel engine.

    PubMed

    Liukonen, Larry R; Weir, Francis W

    2005-03-01

    Diesel engines have historically used asbestos-containing gaskets leading to concerns of fiber release and mechanic exposure. Other published studies regarding asbestos fiber release during gasket removal have reported on short-duration events; were conducted under simulated work conditions; or had other limitations. There are no comprehensive studies relating to diesel engine gaskets under conditions similar to those reported herein, evaluating asbestos fiber release from gaskets during all facets of a complete disassembly and cleaning of a medium duty diesel engine in a busy repair and service shop by a journeyman mechanic. Asbestos content of all gaskets was identified; all disassembly tasks were described and timed; and personal and area air monitoring was conducted for each task. Twenty seven of thirty three gaskets contained chrysotile asbestos in concentrations that ranged from 5 to 70%. All but one air monitoring sample reported results below the limit of reliable detection even though plumes of visible dust were evident during various removal, cleaning, and buffing procedures. The detection limit for airborne asbestos fibers in this investigation was influenced by the presence of other shop dust in the air. Our investigation demonstrates that using shop-standard procedures in an established repair facility, a journeyman mechanic has very little potential for exposure to airborne asbestos fibers during disassembly of an engine, approximately 10% or less than that currently considered to be acceptable by OSHA.

  17. Cosmic: Carbon Monoxide And Soot In Microgravity Inverse Combustion

    NASA Technical Reports Server (NTRS)

    Mikofski, M. A.; Blevins, L. G.; Davis, R. W.; Moore, E. F.; Mulholland, G. W.; Sacksteder, Kurt (Technical Monitor)

    2003-01-01

    Almost seventy percent of fire related deaths are caused by the inhalation of toxins such as CO and soot that are produced when fires become underventilated.(1) Although studies have established the importance of CO formation during underventilated burning,(2) the formation processes of CO (and soot) in underventilated fires are not well understood. The goal of the COSMIC project is to study the formation processes of CO and soot in underventilated flames. A potential way to study CO and soot production in underventilated flames is the use of inverse diffusion flames (IDFs). An IDF forms between a central air jet and a surrounding fuel jet. IDFs are related to underventilated flames because they may allow CO and soot to escape unoxidized. Experiments and numerical simulations of laminar IDFs of CH4 and C2H4 were conducted in 1-g and micro-g to study CO and soot formation. Laminar flames were studied because turbulent models of underventilated fires are uncertain. Microgravity was used to alter CO and soot pathways. A IDF literature survey, providing background and establishing motivation for this research, was presented at the 5th IWMC.(3) Experimental results from 1-g C2H4 IDFs and comparisons with simulations, demonstrating similarities between IDFs and underventilated fires, were presented at the 6th IWMC.(4) This paper will present experimental results from micro-g and 1-g IDFs of CH4 and C2H4 as well as comparisons with simulations, further supporting the relation between IDFs and underventilated flames.

  18. Structure of Soot-Containing Laminar Jet Diffusion Flames

    NASA Technical Reports Server (NTRS)

    Mortazavi, S.; Sunderland, P. B.; Jurng, J.; Koylu, U. O.; Faeth, G. M.

    1993-01-01

    The structure and soot properties of nonbuoyant and weakly-buoyant round jet diffusion flames were studied, considering ethylene, propane and acetylene burning in air at pressures of 0.125-2.0 atm. Measurements of flame structure included radiative heat loss fractions, flame shape and temperature distributions in the fuel-lean (overfire) region. These measurements were used to evaluate flame structure predictions based on the conserved-scalar formalism in conjunction with the laminar flamelet concept, finding good agreement betweem predictions and measurements. Soot property measurements included laminar smoke points, soot volume function distributions using laser extinction, and soot structure using thermophoretic sampling and analysis by transmission electron microscopy. Nonbuoyant flames were found to exhibit laminar smoke points like buoyant flames but their properties are very different; in particular, nonbuoyant flames have laminar smoke point flame lengths and residence times that are shorter and longer, respectively, than buoyant flames.

  19. Soot and Radiation Measurements in Microgravity Jet Diffusion Flames

    NASA Technical Reports Server (NTRS)

    Ku, Jerry C.

    1996-01-01

    The subject of soot formation and radiation heat transfer in microgravity jet diffusion flames is important not only for the understanding of fundamental transport processes involved but also for providing findings relevant to spacecraft fire safety and soot emissions and radiant heat loads of combustors used in air-breathing propulsion systems. Our objectives are to measure and model soot volume fraction, temperature, and radiative heat fluxes in microgravity jet diffusion flames. For this four-year project, we have successfully completed three tasks, which have resulted in new research methodologies and original results. First is the implementation of a thermophoretic soot sampling technique for measuring particle size and aggregate morphology in drop-tower and other reduced gravity experiments. In those laminar flames studied, we found that microgravity soot aggregates typically consist of more primary particles and primary particles are larger in size than those under normal gravity. Comparisons based on data obtained from limited samples show that the soot aggregate's fractal dimension varies within +/- 20% of its typical value of 1.75, with no clear trends between normal and reduced gravity conditions. Second is the development and implementation of a new imaging absorption technique. By properly expanding and spatially-filtering the laser beam to image the flame absorption on a CCD camera and applying numerical smoothing procedures, this technique is capable of measuring instantaneous full-field soot volume fractions. Results from this technique have shown the significant differences in local soot volume fraction, smoking point, and flame shape between normal and reduced gravity flames. We observed that some laminar flames become open-tipped and smoking under microgravity. The third task we completed is the development of a computer program which integrates and couples flame structure, soot formation, and flame radiation analyses together. We found good

  20. The single scattering properties of soot aggregates with concentric core-shell spherical monomers

    NASA Astrophysics Data System (ADS)

    Wu, Yu; Cheng, Tianhai; Gu, Xingfa; Zheng, Lijuan; Chen, Hao; Xu, Hui

    2014-03-01

    Anthropogenic soot aerosols are shown as complex, fractal-like aggregated structures with high light absorption efficiency. In atmospheric environment, soot monomers may tend to acquire a weakly absorbing coating, such as an organic coating, which introduces further complexity to the optical properties of the aggregates. The single scattering properties of soot aggregates can be significantly influenced by the coated status of these kinds of aerosols. In this article, the monomers of fractal soot aggregates are modelled as semi-external mixtures (physical contact) with constant radius of soot core and variable sizes of the coating for specific soot volume fractions. The single scattering properties of these coated soot particles, such as phase function, the cross sections of extinction and absorption, single scattering albedo (SSA) and asymmetry parameter (ASY), are calculated using the numerically exact superposition T-matrix method. The random-orientation averaging results have shown that the single scattering properties of these coated soot aggregates are significantly different from the single volume-equivalent core-shell sphere approximation using the Mie theory and the homogeneous aggregates with uncoated monomers using the effective medium theory, such as Maxwell-Garnett and Bruggemann approximations, which overestimate backscattering of coated soot. It is found that the SSA and cross sections of extinction and absorption are increased for soot aggregates with thicker weakly absorbing coating on the monomers. Especially, the SSA values of these simulated aggregates with less soot core volume fractions are remarkably (~50% for core volume fraction of soot aggregates of 0.5, ~100% for a core volume fraction of 0.2, at 0.67 μm) larger than for uncoated soot particles without consideration of coating. Moreover, the cross sections of extinction and absorption are underestimated by the computation of equivalent homogeneous fractal aggregate approximation (within

  1. Fluxes of Soot Carbon to South Atlantic Sediments

    EPA Science Inventory

    Deep sea sediment samples from the South Atlantic Ocean were analyzed for soot black carbon (BC), total organic carbon (TOC), stable carbon isotope ratios (δ 13C), and polycyclic aromatic hydrocarbons (PAHs). Soot BC was present at low concentrations (0.04–0.17% dry weight), but ...

  2. Experimental study of the interaction of HO2 radicals with soot surface.

    PubMed

    Bedjanian, Yuri; Lelièvre, Stéphane; Le Bras, Georges

    2005-01-21

    The reaction of HO2 with toluene and kerosene flame soot was studied over the temperature range 240-350 K and at P = 0.5-5 Torr of helium using a discharge flow reactor coupled to a modulated molecular beam mass spectrometer. A flat-flame burner was used for the preparation and deposition of soot samples from premixed flames of liquid fuels under well controlled and adjustable combustion conditions. The independent of temperature in the range 240-350 K value of gamma = (7.5 +/- 1.5) x 10(-2) (calculated with geometric surface area) was found for the uptake coefficient of HO2 on kerosene and toluene soot. No significant deactivation of soot surface during its reaction with HO2 was observed. Experiments on soot ageing under ambient conditions showed that the reactivity of aged soot is similar to that of freshly prepared soot samples. The results show that the HO2 + soot reaction could be a significant loss process for HOx in the urban atmosphere with a potential impact on photochemical ozone formation. In contrast this process will be negligible in the upper troposphere even in flight corridors.

  3. Radiative properties of flame-generated soot

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Koeylue, U.O.; Faeth, G.M.

    1993-05-01

    Approximate methods for estimating the optical properties of flame-generated soot aggregates were evaluated using existing computer simulations and measurements in the visible and near-infrared portions of the spectrum. The following approximate methods were evaluated for both individual aggregates and polydisperse aggregate populations: the Rayleigh scattering approximation, Mie scattering for an equivalent sphere, and Rayleigh-Debye-Gans (R-D-G) scattering for both given and fractal aggregates. Results of computer simulations involved both prescribed aggregate geometry and numerically generated aggregates by cluster-cluster aggregation; multiple scattering was considered exactly using the mean-field approximation, and ignored using the R-D-G approximation. Measurements involved the angular scattering properties ofmore » soot in the postflame regions of both premixed and nonpremixed flames. The results show that available computer simulations and measurements of soot aggregate optical properties are not adequate to provide a definitive evaluation of the approximate prediction methods. 40 refs., 7 figs., 1 tab.« less

  4. Army Research Office and Air Force Office of Scientific Research; 1998 Contractors’ Meeting in Chemical Propulsion Held in Long Beach, California on 29 June-1 July 1998

    DTIC Science & Technology

    1998-07-29

    of an operating Cummins NH diesel engine . TECHNICAL DISCUSSION: The chemistry of soot formation has been the subject of extensive research for many...Army Research Office. 14. SUBJECT TERMS Flames, Propulsion, Gas Turbines, Diesel Engines , Scramjets, Soot, Sprays, Turbulence, Diagnostics 17...Menon, Y. Neumeier, J. V. R. Prasad, L. Sankar, J. Seitzman; Georgia Institute of Technology Analysis of Advanced Direct-Injection Diesel Engine

  5. Electron microscopic study of soot particulate matter emissions from aircraft turbine engines.

    PubMed

    Liati, Anthi; Brem, Benjamin T; Durdina, Lukas; Vögtli, Melanie; Dasilva, Yadira Arroyo Rojas; Eggenschwiler, Panayotis Dimopoulos; Wang, Jing

    2014-09-16

    The microscopic characteristics of soot particulate matter (PM) in gas turbine exhaust are critical for an accurate assessment of the potential impacts of the aviation industry on the environment and human health. The morphology and internal structure of soot particles emitted from a CFM 56-7B26/3 turbofan engine were analyzed in an electron microscopic study, down to the nanoscale, for ∼ 100%, ∼ 65%, and ∼ 7% static engine thrust as a proxy for takeoff, cruising, and taxiing, respectively. Sampling was performed directly on transmission electron microscopy (TEM) grids with a state-of-the-art sampling system designed for nonvolatile particulate matter. The electron microscopy results reveal that ∼ 100% thrust produces the highest amount of soot, the highest soot particle volume, and the largest and most crystalline primary soot particles with the lowest oxidative reactivity. The opposite is the case for soot produced during taxiing, where primary soot particles are smallest and most reactive and the soot amount and volume are lowest. The microscopic characteristics of cruising condition soot resemble the ones of the ∼ 100% thrust conditions, but they are more moderate. Real time online measurements of number and mass concentration show also a clear correlation with engine thrust level, comparable with the TEM study. The results of the present work, in particular the small size of primary soot particles present in the exhaust (modes of 24, 20, and 13 nm in diameter for ∼ 100%, ∼ 65% and ∼ 7% engine thrust, respectively) could be a concern for human health and the environment and merit further study. This work further emphasizes the significance of the detailed morphological characteristics of soot for assessing environmental impacts.

  6. On the radiative properties of soot aggregates - Part 2: Effects of coating

    NASA Astrophysics Data System (ADS)

    Liu, Fengshan; Yon, Jérôme; Bescond, Alexandre

    2016-03-01

    The effects of weakly absorbing material coating on soot have attracted considerable research attention in recent years due to the significant influence of such coating on soot radiative properties and the large differences predicted by different numerical models. Soot aggregates were first numerically generated using the diffusion limited cluster aggregation algorithm to produce fractal aggregates formed by log-normally distributed polydisperse spherical primary particles in point-touch. These aggregates were then processed by adding a certain amount of primary particle overlapping and necking to simulate the soot morphology observed from transmission electron microscopy images. After this process, a layer of WAM coating of different thicknesses was added to these more realistic soot aggregates. The radiative properties of these coated soot aggregates over the spectral range of 266-1064 nm were calculated by the discrete dipole approximation (DDA) using the spectrally dependent refractive index of soot for four aggregates containing Np=1, 20, 51 and 96 primary particles. The considered coating thicknesses range from 0% (no coating) up to 100% coating in terms of the primary particle diameter. Coating enhances both the particle absorption and scattering cross sections, with much stronger enhancement to the scattering one, as well as the asymmetry factor and the single scattering albedo. The absorption enhancement is stronger in the UV than in the visible and the near infrared. The simple corrections to the Rayleigh-Debye-Gans fractal aggregates theory for uncoated soot aggregates are found not working for coated soot aggregates. The core-shell model significantly overestimates the absorption enhancement by coating in the visible and the near infrared compared to the DDA results of the coated soot particle. Treating an externally coated soot aggregate as an aggregate formed by individually coated primary particles significantly underestimates the absorption

  7. Soot Surface Oxidation in Laminar Hydrocarbon/Air Diffusion Flames at Atmospheric Pressure. Appendix I

    NASA Technical Reports Server (NTRS)

    Xu, F.; El-Leathy, A. M.; Kim, C. H.; Faeth, G. M.; Yuan, Z.-G. (Technical Monitor); Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

    2003-01-01

    Soot surface oxidation was studied experimentally in laminar hydrocarbon/air diffusion flames at atmospheric pressure. Measurements were carried out along the axes of round fuel jets burning in coflowing dry air considering acetylene-nitrogen, ethylene, propyiene-nitrogen, propane and acetylene-benzene-nitrogen in the fuel stream. Measurements were limited to the initial stages of soot oxidation (carbon consumption less than 70%) where soot oxidation occurs at the surface of primary soot particles. The following properties were measured as a function of distance above the burner exit: soot concentrations by deconvoluted laser extinction, soot temperatures by deconvoluted multiline emission, soot structure by thermophoretic sampling and analysis using Transmission Electron Microscopy (TEM), concentrations of major stable gas species (N2, H2O, H2, O2, CO, CO2, CH4, C2H2, C2H6, C3H6, C3H8, and C6H6) by sampling and gas chromatography, concentrations of some radical species (H, OH, O) by deconvoluted Li/LiOH atomic absorption and flow velocities by laser velocimetry. For present test conditions, it was found that soot surface oxidation rates were not affected by fuel type, that direct rates of soot surface oxidation by O2 estimated from Nagle and Strickland-Constable (1962) were small compared to observed soot surface oxidation rates because soot surface oxidation was completed near the flame sheet where O2 concentrations were less than 3% by volume, and that soot surface oxidation rates were described by the OH soot surface oxidation mechanism with a collision efficiency of 0.14 and an uncertainty (95% confidence) of +/- 0.04 when allowing for direct soot surface oxidation by O2, which is in reasonably good agreement with earlier observations of soot surface oxidation rates in both premixed and diffusion flames at atmospheric pressure.

  8. On Soot Inception in Nonpremixed Flames and the Effects of Flame Structure

    NASA Technical Reports Server (NTRS)

    Chao, B. H.; Liu, S.; Axelbaum, R. L.; Gokoglu, Suleyman (Technical Monitor)

    1998-01-01

    A simplified three-step model of soot inception has been employed with high activation energy asymptotics to study soot inception in nonpremixed counterflow systems with emphasis on understanding the effects of hydrodynamics and transport. The resulting scheme yields three zones: (1) a fuel oxidation zone wherein the fuel and oxidizer react to form product as well as a radical R, (e.g., H), (2) a soot/precursor formation zone where the radical R reacts with fuel to form "soot/precursor" S, and (3) a soot/precursor consumption zone where S reacts with the oxidizer to form product. The kinetic scheme, although greatly simplified, allows the coupling between soot inception and flame structure to be assessed. The results yield flame temperature, flame location, and a soot/precursor index S(sub I) as functions of Damkohler number for S formation. The soot/precursor index indicates the amount of S at the boundary of the formation region. The flame temperature indirectly indicates the total amount of S integrated over the formation region because as S is formed less heat release is available. The results show that unlike oxidation reactions, an extinction turning-point behavior does not exist for soot. Instead, the total amount of S slowly decreases with decreasing Damkohler number (increasing strain rate), which is consistent with counterflow flame experiments. When the Lewis number of the radical is decreased from unity, the total S reduces due to reduced residence time for the radical in the soot formation region. Similarly, when the Lewis number of the soot/precursor is increased from unity the amount of S increases for all Damkohler numbers. In addition to studying fuel-air (low stoichiometric mixture fraction) flames, the air-side nitrogen was substituted into the fuel, yielding diluted fuel-oxygen (high stoichiometric mixture fraction) flames with the same flame temperature as the fuel - air flames. The relative flame locations were different however, and

  9. Soot agglomeration in isolated, free droplet combustion

    NASA Technical Reports Server (NTRS)

    Choi, M. Y.; Dryer, F. L.; Green, G. J.; Sangiovanni, J. J.

    1993-01-01

    Under the conditions of an isolated, free droplet experiment, hollow, carbonaceous structures, called soot spheres, were observed to form during the atmospheric pressure, low Reynolds number combustion of 1-methylnaphthalene. These structures which are agglomerates composed of smaller spheroidal units result from both thermophoretic effects induced by the envelope flame surrounding each drop and aerodynamic effects caused by changes in the relative gas/drop velocities. A chemically reacting flow model was used to analyze the process of sootshell formation during microgravity droplet combustion. The time-dependent temperature and gas property field surrounding the droplet was determined, and the soot cloud location for microgravity combustion of n-heptane droplets was predicted. Experiments showed that the sooting propensity of n-alkane fuel droplets can be varied through diluent substitution, oxygen-index variations, and ambient pressure reductions.

  10. Particulate matter from both heavy fuel oil and diesel fuel shipping emissions show strong biological effects on human lung cells at realistic and comparable in vitro exposure conditions.

    PubMed

    Oeder, Sebastian; Kanashova, Tamara; Sippula, Olli; Sapcariu, Sean C; Streibel, Thorsten; Arteaga-Salas, Jose Manuel; Passig, Johannes; Dilger, Marco; Paur, Hanns-Rudolf; Schlager, Christoph; Mülhopt, Sonja; Diabaté, Silvia; Weiss, Carsten; Stengel, Benjamin; Rabe, Rom; Harndorf, Horst; Torvela, Tiina; Jokiniemi, Jorma K; Hirvonen, Maija-Riitta; Schmidt-Weber, Carsten; Traidl-Hoffmann, Claudia; BéruBé, Kelly A; Wlodarczyk, Anna J; Prytherch, Zoë; Michalke, Bernhard; Krebs, Tobias; Prévôt, André S H; Kelbg, Michael; Tiggesbäumker, Josef; Karg, Erwin; Jakobi, Gert; Scholtes, Sorana; Schnelle-Kreis, Jürgen; Lintelmann, Jutta; Matuschek, Georg; Sklorz, Martin; Klingbeil, Sophie; Orasche, Jürgen; Richthammer, Patrick; Müller, Laarnie; Elsasser, Michael; Reda, Ahmed; Gröger, Thomas; Weggler, Benedikt; Schwemer, Theo; Czech, Hendryk; Rüger, Christopher P; Abbaszade, Gülcin; Radischat, Christian; Hiller, Karsten; Buters, Jeroen T M; Dittmar, Gunnar; Zimmermann, Ralf

    2015-01-01

    Ship engine emissions are important with regard to lung and cardiovascular diseases especially in coastal regions worldwide. Known cellular responses to combustion particles include oxidative stress and inflammatory signalling. To provide a molecular link between the chemical and physical characteristics of ship emission particles and the cellular responses they elicit and to identify potentially harmful fractions in shipping emission aerosols. Through an air-liquid interface exposure system, we exposed human lung cells under realistic in vitro conditions to exhaust fumes from a ship engine running on either common heavy fuel oil (HFO) or cleaner-burning diesel fuel (DF). Advanced chemical analyses of the exhaust aerosols were combined with transcriptional, proteomic and metabolomic profiling including isotope labelling methods to characterise the lung cell responses. The HFO emissions contained high concentrations of toxic compounds such as metals and polycyclic aromatic hydrocarbon, and were higher in particle mass. These compounds were lower in DF emissions, which in turn had higher concentrations of elemental carbon ("soot"). Common cellular reactions included cellular stress responses and endocytosis. Reactions to HFO emissions were dominated by oxidative stress and inflammatory responses, whereas DF emissions induced generally a broader biological response than HFO emissions and affected essential cellular pathways such as energy metabolism, protein synthesis, and chromatin modification. Despite a lower content of known toxic compounds, combustion particles from the clean shipping fuel DF influenced several essential pathways of lung cell metabolism more strongly than particles from the unrefined fuel HFO. This might be attributable to a higher soot content in DF. Thus the role of diesel soot, which is a known carcinogen in acute air pollution-induced health effects should be further investigated. For the use of HFO and DF we recommend a reduction of

  11. Gas and Particle Oxidation Products from Ozone Aging of Airborne Diesel Particles

    NASA Astrophysics Data System (ADS)

    Holmen, B. A.; Chen, Z.

    2005-12-01

    Diesel exhaust emissions contain fine particulate matter (PM2.5) composed of carbon-based particles with adsorbed compounds, including water soluble and insoluble substances. Many nonpolar organic compounds associated with diesel particulate matter (DPM) are known to be mutagenic and carcinogenic. In the presence of ozone, these DPM compounds can be transformed into polar species that are more toxic and poorly characterized. Understanding the gas and particle reaction products from DPM aging in the presence of tropospheric ozone is important for air quality, climate change and aerosol health effects. Aging experiments were conducted in a flow reactor to identify gas and particle-phase reaction products of DPM exposed to ambient levels of ozone. Diesel bus exhaust particles were collected on filters and then exposed to 0.1 - 0.5 ppm O3 for 0 to 72 h. Gaseous polar organic products formed during the aging experiments were collected on Tenax TA adsorbent coated with PFBHA derivatization agent. A thermal desorption gas chromatography mass spectrometry (TD/GC/MS) method was developed to determine gas-phase and particle-phase organic compounds. PFBHA and BSTFA derivatization agents converted polar species into less polar analogues prior to analysis. Preliminary results indicate that DPM hydrocarbons react with O3 to form many gas-phase polar products containing C=O (carbonyl) and COOH (carboxy) functional groups. Particle-phase PAH and alkane concentrations decreased significantly depending on time of exposure.

  12. Darkness after the K-T impact: Effects of soot

    NASA Technical Reports Server (NTRS)

    Wolbach, Wendy S.; Anders, Edward; Orth, Charles J.

    1988-01-01

    Dust from the K-T impact apparently settled from the atmosphere in less than 6 months, restoring sunlight to minimum photosynthesis levels in about 4 months. However, the discovery of a global soot component in the boundary clay makes it necessary to reconsider the problem, as soot particles not only are smaller (0.1 vs. about 0.5 micrometer) and thus settle more slowly, but also are better light absorbers (optical depth of 13 mg soot cm(-2) about 1800; and are more resistant to rainout. Still, the darkness cannot have lasted very much longer than 6 months, else no larger animals would have survived. Perhaps the soot coagulated with the rock dust and fell out with it. Evidence on this point may be sought at a relatively undisturbed K-T boundary site, such as Woodside Creek, N.Z. There the boundary clay and lowermost Tertiary strata are finely laminated and show large chemical and isotopic differences on a millimeter scale, apparently representing a detailed time sequence. Researchers studied a 3 m section across the boundary at this site, analyzing the principal forms of carbon (soot, elemental C, kerogen, and carbonate) as well as 33 elements. Correlations among the elements were sought. Apparently soot came early and coagulated with the ejecta, staying with them for the primary fallout and in the next 5 cm, but then parting company, perhaps due to size sorting.

  13. Bioaccessibility of PAHs and PAH derivatives in a fuel soot assessed by an in vitro digestive model with absorptive sink: Effects of aging the soot in a soil-water mixture.

    PubMed

    Zhang, Yanyan; Pignatello, Joseph J; Tao, Shu

    2018-02-15

    Aging soot in soil under neutral aqueous condition for 30days significantly (p<0.05) reduced the apparent gastrointestinal bioaccessibility (B app ) of polycyclic aromatic hydrocarbons (PAHs) and PAH derivatives (d-PAHs) natively present in a composite fuel soot sample. B app was determined under fasting conditions by a previously developed in vitro digestive model that includes silicone sheet as a third phase absorptive sink in the small intestinal stage. Redistribution of contaminants from soot to soil, determined in independent experiments, was too small to affect B app . Prior uptake by soot of a commercial humic acid representing dissolved soil organic matter had no impact on B app . We identified two causes for the reduction in B app by soil and found they were approximately additive. One is an aging time-independent "matrix effect" attributable to competitive sorption by the soil of labile contaminant that is desorbed from the soot during the digestion test. The other is the dissolution of soluble substances from the soot during the aging process that increases soot surface area and nanoporosity. The increased surface area and nanoporosity drive contaminants from labile to nonlabile states in the soot and decrease the desorption into the digestive fluid, the former contributing most to the reduction in B app . The present study shows that mixing of raw soot with soil has important effects, both aging and non-aging, on the bioaccessibility of soot-borne contaminants. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Density Gradient Separation of Detonation Soot for Nanocarbon Characterization

    NASA Astrophysics Data System (ADS)

    Ringstrand, Bryan; Jungjohann, Katie; Seifert, Sonke; Firestone, Millicent; Podlesak, David

    2017-06-01

    Detonation of high explosives (HE) can expand our understanding of chemical bonding at extreme conditions as well as the opportunity to prepare carbon nanomaterials. In order to understand detonation mechanisms, nanocarbon characterization contained within the soot is paramount. Thus, benign purification methods for detonation soot are important for its characterization. Progress towards a non-traditional approach to detonation soot processing is presented. Purification of soot using heavy liquid media such as sodium polytungstate to separate soot components based on their density was tested based on the premise that different nanocarbons possess different densities [ ρ = 1.79 g/cm3 (graphene) and ρ = 3.05 g/cm3 (nanodiamond)]. Analysis using XRD, SAXS, WAXS, Raman, XPS, TEM, and NMR provided information about particle morphology and carbon hybridization. Detonation synthesis offers an avenue for the discovery of new carbon frameworks. In addition, understanding reactions at extreme conditions provides for more accurate predictions of HE performance, explosion intent, and simulation refinement. These results are of interest to both the nanoscience and shock physics communities. We acknowledge the support of the U.S. Department of Energy LANL/LDRD Program (LANL #20150050DR). LA-UR-17-21502.

  15. Construction of combustion models for rapeseed methyl ester bio-diesel fuel for internal combustion engine applications.

    PubMed

    Golovitchev, Valeri I; Yang, Junfeng

    2009-01-01

    Bio-diesel fuels are non-petroleum-based diesel fuels consisting of long chain alkyl esters produced by the transesterification of vegetable oils, that are intended for use (neat or blended with conventional fuels) in unmodified diesel engines. There have been few reports of studies proposing theoretical models for bio-diesel combustion simulations. In this study, we developed combustion models based on ones developed previously. We compiled the liquid fuel properties, and the existing detailed mechanism of methyl butanoate ester (MB, C(5)H(10)O(2)) oxidation was supplemented by sub-mechanisms for two proposed fuel constituent components, C(7)H(16) and C(7)H(8)O (and then, by mp2d, C(4)H(6)O(2) and propyne, C(3)H(4)) to represent the combustion model for rapeseed methyl ester described by the chemical formula, C(19)H(34)O(2) (or C(19)H(36)O(2)). The main fuel vapor thermal properties were taken as those of methyl palmitate C(19)H(36)O(2) in the NASA polynomial form of the Burcat database. The special global reaction was introduced to "crack" the main fuel into its constituent components. This general reaction included 309 species and 1472 reactions, including soot and NO(x) formation processes. The detailed combustion mechanism was validated using shock-tube ignition-delay data under diesel engine conditions. For constant volume and diesel engine (Volvo D12C) combustion modeling, this mechanism could be reduced to 88 species participating in 363 reactions.

  16. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Braun,A.; Huggins, F.; Kelly, K.

    We report on the structure of a set of diesel exhaust samples that were obtained from reference diesel fuel and diesel fuel mixed with ferrocene. Characterization was carried out with X-ray absorption spectroscopy (C(1s) NEXAFS) and wide-angle X-ray scattering (WAXS). The reference diesel soot shows a pronounced graphite-like microstructure and molecular structure, with a strong (0 0 2) graphite Bragg reflex and a strong aromatic C{double_bond}C resonance at 285 eV. The mineral matter in the reference soot could be identified as Fe{sub 2}O{sub 3} hematite. The soot specimen from the diesel mixed with ferrocene has an entirely different structure andmore » lacks significantly in graphite-like characteristics. NEXAFS spectra of such soot barely show aromatics but pronounced contributions from aliphatic structures. WAXS patterns show almost no intensity at the Bragg (0 0 2) reflection of graphite, but a strong aliphatic {gamma}-side band. The iron from the ferrocene transforms to Fe{sub 2}O{sub 3} maghemite.« less

  17. Effective density and mixing state of aerosol particles in a near-traffic urban environment.

    PubMed

    Rissler, Jenny; Nordin, Erik Z; Eriksson, Axel C; Nilsson, Patrik T; Frosch, Mia; Sporre, Moa K; Wierzbicka, Aneta; Svenningsson, Birgitta; Löndahl, Jakob; Messing, Maria E; Sjogren, Staffan; Hemmingsen, Jette G; Loft, Steffen; Pagels, Joakim H; Swietlicki, Erik

    2014-06-03

    In urban environments, airborne particles are continuously emitted, followed by atmospheric aging. Also, particles emitted elsewhere, transported by winds, contribute to the urban aerosol. We studied the effective density (mass-mobility relationship) and mixing state with respect to the density of particles in central Copenhagen, in wintertime. The results are related to particle origin, morphology, and aging. Using a differential mobility analyzer-aerosol particle mass analyzer (DMA-APM), we determined that particles in the diameter range of 50-400 nm were of two groups: porous soot aggregates and more dense particles. Both groups were present at each size in varying proportions. Two types of temporal variability in the relative number fraction of the two groups were found: soot correlated with intense traffic in a diel pattern and dense particles increased during episodes with long-range transport from polluted continental areas. The effective density of each group was relatively stable over time, especially of the soot aggregates, which had effective densities similar to those observed in laboratory studies of fresh diesel exhaust emissions. When heated to 300 °C, the soot aggregate volatile mass fraction was ∼10%. For the dense particles, the volatile mass fraction varied from ∼80% to nearly 100%.

  18. Developing a predictive model for the chemical composition of soot nanoparticles

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Violi, Angela; Michelsen, Hope; Hansen, Nils

    In order to provide the scientific foundation to enable technology breakthroughs in transportation fuel, it is important to develop a combustion modeling capability to optimize the operation and design of evolving fuels in advanced engines for transportation applications. The goal of this proposal is to develop a validated predictive model to describe the chemical composition of soot nanoparticles in premixed and diffusion flames. Atomistic studies in conjunction with state-of-the-art experiments are the distinguishing characteristics of this unique interdisciplinary effort. The modeling effort has been conducted at the University of Michigan by Prof. A. Violi. The experimental work has entailed amore » series of studies using different techniques to analyze gas-phase soot precursor chemistry and soot particle production in premixed and diffusion flames. Measurements have provided spatial distributions of polycyclic aromatic hydrocarbons and other gas-phase species and size and composition of incipient soot nanoparticles for comparison with model results. The experimental team includes Dr. N. Hansen and H. Michelsen at Sandia National Labs' Combustion Research Facility, and Dr. K. Wilson as collaborator at Lawrence Berkeley National Lab's Advanced Light Source. Our results show that the chemical and physical properties of nanoparticles affect the coagulation behavior in soot formation, and our results on an experimentally validated, predictive model for the chemical composition of soot nanoparticles will not only enhance our understanding of soot formation since but will also allow the prediction of particle size distributions under combustion conditions. These results provide a novel description of soot formation based on physical and chemical properties of the particles for use in the next generation of soot models and an enhanced capability for facilitating the design of alternative fuels and the engines they will power.« less

  19. Soot Combustion over Nanostructured Ceria with Different Morphologies

    PubMed Central

    Zhang, Wen; Niu, Xiaoyu; Chen, Liqiang; Yuan, Fulong; Zhu, Yujun

    2016-01-01

    In this study, nano-structure ceria with three different morphologies (nanorod, nanoparticle and flake) have been prepared by hydrothermal and solvothermal methods. The ceria samples were deeply characterized by XRD, SEM, TEM, H2-TPR, XPS and in-situ DRIFTS, and tested for soot combustion in absence/presence NO atmospheres under loose and tight contact conditions. The prepared ceria samples exhibit excellent catalytic activities, especially, the CeO2 with nanorod (Ce-R) shows the best catalytic activity, for which the peak temperature of soot combustion (Tm) is about 500 and 368 °C in loose and tight contact conditions, respectively. The catalytic activity for Ce-R is higher than that of the reported CeO2 catalysts and reaches a level that of precious metals. The characterization results reveal that the maximal amounts of adsorbed oxygen species on the surface of the nanostructure Ce-R catalyst should be the crucial role to decide the catalytic soot performance. High BET surface area may also be a positive effect on soot oxidation activity under loose contact conditions. PMID:27353143

  20. Modeling accumulations of particles in lung during chronic inhalation exposures that lead to impaired clearance

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wolff, R.K.; Griffith, W.C. Jr.; Cuddihy, R.G.

    Chronic inhalation of insoluble particles of low toxicity that produce substantial lung burdens of particles, or inhalation of particles that are highly toxic to the lung, can impair clearance. This report describes model calculations of accumulations in lung of inhaled low-toxicity diesel exhaust soot and high-toxicity Ga2O3 particles. Lung burdens of diesel soot were measured periodically during a 24-mo exposure to inhaled diesel exhaust at soot concentrations of 0, 0.35, 3.5, and 7 mg m-3, 7 h d-1, 5 d wk-1. Lung burdens of Ga2O3 were measured for 1 y after a 4-wk exposure to 23 mg Ga2O3 m-3, 2more » h d-1, 5 d wk-1. Lung burdens of Ga2O3 were measured for 1 y both studies using inhaled radiolabeled tracer particles. Simulation models fit the observed lung burdens of diesel soot in rats exposed to the 3.5- and 7-mg m-3 concentrations of soot only if it was assumed that clearance remained normal for several months, then virtually stopped. Impaired clearance from high-toxicity particles occurred early after accumulations of a low burden, but that from low-toxicity particles was evident only after months of exposure, when high burdens had accumulated in lung. The impairment in clearances of Ga2O3 particles and radiolabeled tracers was similar, but the impairment in clearance of diesel soot and radiolabeled tracers differed in magnitude. This might have been related to differences in particle size and composition between the tracers and diesel soot. Particle clearance impairment should be considered both in the design of chronic exposures of laboratory animals to inhaled particles and in extrapolating the results to people.« less

  1. Effect of open channel filter on particle emissions of modern diesel engine.

    PubMed

    Heikkilä, Juha; Rönkkö, Topi; Lähde, Tero; Lemmetty, Mikko; Arffman, Anssi; Virtanen, Annele; Keskinen, Jorma; Pirjola, Liisa; Rothe, Dieter

    2009-10-01

    Particle emissions of modern diesel engines are of a particular interest because of their negative health effects. The special interest is in nanosized solid particles. The effect of an open channel filter on particle emissions of a modern heavy-duty diesel engine (MAN D2066 LF31, model year 2006) was studied. Here, the authors show that the open channel filter made from metal screen efficiently reduced the number of the smallest particles and, notably, the number and mass concentration of soot particles. The filter used in this study reached 78% particle mass reduction over the European Steady Cycle. Considering the size-segregated number concentration reduction, the collection efficiency was over 95% for particles smaller than 10 nm. The diffusion is the dominant collection mechanism in small particle sizes, thus the collection efficiency decreased as particle size increased, attaining 50% at 100 nm. The overall particle number reduction was 66-99%, and for accumulation-mode particles the number concentration reduction was 62-69%, both depending on the engine load.

  2. Influence of polymethyl acrylate additive on the formation of particulate matter and NOX emission of a biodiesel-diesel-fueled engine.

    PubMed

    Monirul, Islam Mohammad; Masjuki, Haji Hassan; Kalam, Mohammad Abdul; Zulkifli, Nurin Wahidah Mohd; Shancita, Islam

    2017-08-01

    The aim of this study is to investigate the effect of the polymethyl acrylate (PMA) additive on the formation of particulate matter (PM) and nitrogen oxide (NO X ) emission from a diesel coconut and/or Calophyllum inophyllum biodiesel-fueled engine. The physicochemical properties of 20% of coconut and/or C. inophyllum biodiesel-diesel blend (B20), 0.03 wt% of PMA with B20 (B20P), and diesel fuel were measured and compared to ASTM D6751, D7467, and EN 14214 standard. The test results showed that the addition of PMA additive with B20 significantly improves the cold-flow properties such as pour point (PP), cloud point (CP), and cold filter plugging point (CFPP). The addition of PMA additives reduced the engine's brake-specific energy consumption of all tested fuels. Engine emission results showed that the additive-added fuel reduce PM concentration than B20 and diesel, whereas the PM size and NO X emission both increased than B20 fuel and baseline diesel fuel. Also, the effect of adding PMA into B20 reduced Carbon (C), Aluminum (Al), Potassium (K), and volatile materials in the soot, whereas it increased Oxygen (O), Fluorine (F), Zinc (Zn), Barium (Ba), Chlorine (Cl), Sodium (Na), and fixed carbon. The scanning electron microscope (SEM) results for B20P showed the lower agglomeration than B20 and diesel fuel. Therefore, B20P fuel can be used as an alternative to diesel fuel in diesel engines to lower the harmful emissions without compromising the fuel quality.

  3. Soot superaggregates from flaming wildfires and their direct radiative forcing

    PubMed Central

    Chakrabarty, Rajan K.; Beres, Nicholas D.; Moosmüller, Hans; China, Swarup; Mazzoleni, Claudio; Dubey, Manvendra K.; Liu, Li; Mishchenko, Michael I.

    2014-01-01

    Wildfires contribute significantly to global soot emissions, yet their aerosol formation mechanisms and resulting particle properties are poorly understood and parameterized in climate models. The conventional view holds that soot is formed via the cluster-dilute aggregation mechanism in wildfires and emitted as aggregates with fractal dimension Df ≈ 1.8 mobility diameter Dm ≤ 1 μm, and aerodynamic diameter Da ≤ 300 nm. Here we report the ubiquitous presence of soot superaggregates (SAs) in the outflow from a major wildfire in India. SAs are porous, low-density aggregates of cluster-dilute aggregates with characteristic Df ≈ 2.6, Dm > 1 μm, and Da ≤ 300 nm that form via the cluster-dense aggregation mechanism. We present additional observations of soot SAs in wildfire smoke-laden air masses over Northern California, New Mexico, and Mexico City. We estimate that SAs contribute, per unit optical depth, up to 35% less atmospheric warming than freshly-emitted (Df ≈ 1.8) aggregates, and ≈90% more warming than the volume-equivalent spherical soot particles simulated in climate models. PMID:24981204

  4. Effects of retrofitting emission control systems on in-use heavy diesel vehicles.

    PubMed

    Millstein, Dev E; Harley, Robert A

    2010-07-01

    Diesel engines are now the largest source of nitrogen oxides (NO(x)) and fine particulate black carbon (soot) emissions in California. The California Air Resources Board recently adopted a rule requiring that by 2014 all in-use heavy trucks and buses meet current (2007) exhaust particulate matter (PM) emission standards. Also by 2023 all in-use heavy-duty vehicles will have to meet current NO(x) emission standards, with significant progress in achieving the requirements for NO(x) control expected by 2014. This will require retrofit or replacement of older in-use engines. Diesel particle filters (DPF) reduce PM emissions but may increase the NO(2)/NO(x) emission ratio to approximately 35%, compared to approximately 5% typical of diesel engines without particle filters. Additionally, DPF with high oxidative capacity reduce CO and hydrocarbon emissions. We evaluate the effects of retrofitting trucks with DPF on air quality in southern California, using an Eulerian photochemical air quality model. Compared to a 2014 reference scenario without the retrofit program, black carbon concentrations decreased by 12 +/- 2% and 14 +/- 2% during summer and fall, respectively, with corresponding increases in ambient ozone concentrations of 3 +/- 2% and 7 +/- 3%. NO(2) concentrations decreased by 2-4% overall despite the increase in primary NO(2) emissions because total NO(x) emissions were reduced as part of the program to retrofit NO(x) control systems on in-use engines. However, in some cases NO(2) concentrations may increase at locations with high diesel truck traffic.

  5. Soot Formation in Laminar Premixed Methane/Oxygen Flames at Atmospheric Pressure. Appendix H

    NASA Technical Reports Server (NTRS)

    Xu, F.; Lin, K.-C.; Faeth, G. M.; Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

    2001-01-01

    Flame structure and soot formation were studied within soot-containing laminar premixed methanefoxygen flames at atmospheric pressure. The following measurements were made: soot volume fractions by laser extinction, soot temperatures by multiline emission, gas temperatures (where soot was absent) by corrected fine-wire thermocouples, soot structure by thermophoretic sampling and transmission electron microscope (TEM), major gas species concentrations by sampling and gas chromatography, and gas velocities by laser velocimetry. Present measurements of gas species concentrations were in reasonably good agreement with earlier measurements due to Ramer et al. as well as predictions based on the detailed mechanisms of Frenklach and co-workers and Leung and Lindstedt; the predictions also suggest that H atom concentrations are in local thermodynamic equilibrium throughout the soot formation region. Using this information, it was found that measured soot surface growth rates could be correlated successfully by predictions based on the hydrogenabstraction/carbon-addition (HACA) mechanisms of both Frenklach and co-workers and Colket and Hall, extending an earlier assessment of these mechanisms for premixed ethylene/air flames to conditions having larger H/C ratios and acetylene concentrations. Measured primary soot particle nucleation rates were somewhat lower than the earlier observations for laminar premixed ethylene/air flames and were significantly lower than corresponding rates in laminar diffusion flames, for reasons that still must be explained.

  6. Effects of Fuel Preheat on Soot Formation in Microgravity Laminar Diffusion Flames

    NASA Technical Reports Server (NTRS)

    Konsur, Bogdan; Megaridis, Constantine M.; Griffin, DeVon W.

    1997-01-01

    Nonbuoyant flames offer themselves as an attractive and promising platform to gain a better understanding of soot mechanisms. The effects of buoyancy can be eliminated temporarily in drop towers which sustain brief intervals of reduced gravity-typically lower than 10(exp -3)g- extending up to several seconds at a time. Microgravity facilities have been employed to show that nonbuoyant flames are longer, wider and sootier than their normal-gravity counterparts. Sunderland et al. recently verified the existence of smoke point in laminar nonbuoyant flames. As reported, microgravity flames operating above their smoke point displayed a blunt tip and much broader soot-containing regimes in comparison to their buoyant counterparts. Mortazavi et al. established that residence times in microgravity laminar jet diffusion flames with Re=0(100) tend to be proportional to burner diameter and inversely proportional to burner exit velocity. This offers the capability to alter residence times in nonbuoyant laminar jet diffusion flames when varying the burner exit diameters and velocities. Megaridis et al. presented a quantitative definition of the soot-field structure within laminar microgravity jet diffusion flames which operated well above their smoke point. The experimental methodology involved a full-field laser-light extinction technique and jet diffusion flames of nitrogen-diluted (50% vol.) acetylene fuel burning in quiescent air at atmospheric pressure. The work was conducted at the 2.2s drop tower of the NASA Lewis Research Center (NASA-LeRC). Parallel work on 1-g flames was also presented in (6) to facilitate comparisons on the effect of gravity on the soot fields. As reported, the soot spatial distributions in 0-g flames did not change in a detectable manner after 1s within a typical 2.2s experiment. During that period, the soot field was shown to sustain a pronounced annular structure throughout the luminous nonbuoyant-flame zone. The maximum soot volume fraction

  7. Measurements of Soot Mass Absorption Coefficients from 300 to 660 nm

    NASA Astrophysics Data System (ADS)

    Renbaum-Wolff, Lindsay; Fisher, Al; Helgestad, Taylor; Lambe, Andrew; Sedlacek, Arthur; Smith, Geoffrey; Cappa, Christopher; Davidovits, Paul; Onasch, Timothy; Freedman, Andrew

    2016-04-01

    Soot, a product of incomplete combustion, plays an important role in the earth's climate system through the absorption and scattering of solar radiation. In particular, the assumed mass absorption coefficient (MAC) of soot and its variation with wavelength presents a significant uncertainty in the calculation of radiative forcing in global climate change models. As part of the fourth Boston College/Aerodyne soot properties measurement campaign, we have measured the mass absorption coefficient of soot produced by an inverted methane diffusion flame over a spectral range of 300-660 nm using a variety of optical absorption techniques. Extinction and absorption were measured using a dual cavity ringdown photoacoustic spectrometer (CRD-PAS, UC Davis) at 405 nm and 532 nm. Scattering and extinction were measured using a CAPS PMssa single scattering albedo monitor (Aerodyne) at 630 nm; the absorption coefficient was determined by subtraction. In addition, the absorption coefficients in 8 wavelength bands from 300 to 660 nm were measured using a new broadband photoacoustic absorption monitor (UGA). Soot particle mass was quantified using a centrifugal particle mass analyzer (CPMA, Cambustion), mobility size with a scanning mobility particle sizer (SMPS, TSI) and soot concentration with a CPC (Brechtel). The contribution of doubly charged particles to the sample mass was determined using a Single Particle Soot Photometer (DMT). Over a mass range of 1-8 fg, corresponding to differential mobility diameters of ~150 nm to 550 nm, the value of the soot MAC proved to be independent of mass for all wavelengths. The wavelength dependence of the MAC was best fit to a power law with an Absorption Ångstrom Coefficient slightly greater than 1.

  8. RELATIONSHIP BETWEEN PCB PLANERITY AND INTERACTIONS WITH SOOT CARBON

    EPA Science Inventory

    There is increasing interest in the role of soot carbon in the strong partitioning of organic contaminants to sediments. Primary interest has been focused on PAHs which have been shown to be affected by the presence of soot carbon in both their geochemical and bioavailability beh...

  9. Maternal diesel inhalation increases airway hyperreactivity in ozone-exposed offspring.

    PubMed

    Auten, Richard L; Gilmour, M Ian; Krantz, Q Todd; Potts, Erin N; Mason, S Nicholas; Foster, W Michael

    2012-04-01

    Air pollutant exposure is linked with childhood asthma incidence and exacerbations, and maternal exposure to airborne pollutants during pregnancy increases airway hyperreactivity (AHR) in offspring. To determine if exposure to diesel exhaust (DE) during pregnancy worsened postnatal ozone-induced AHR, timed pregnant C57BL/6 mice were exposed to DE (0.5 or 2.0 mg/m(3)) 4 hours daily from Gestation Day 9-17, or received twice-weekly oropharyngeal aspirations of the collected DE particles (DEPs). Placentas and fetal lungs were harvested on Gestation Day 18 for cytokine analysis. In other litters, pups born to dams exposed to air or DE, or to dams treated with aspirated diesel particles, were exposed to filtered air or 1 ppm ozone beginning the day after birth, for 3 hours per day, 3 days per week for 4 weeks. Additional pups were monitored after a 4-week recovery period. Diesel inhalation or aspiration during pregnancy increased levels of placental and fetal lung cytokines. There were no significant effects on airway leukocytes, but prenatal diesel augmented ozone-induced elevations of bronchoalveolar lavage cytokines at 4 weeks. Mice born to the high-concentration diesel-exposed dams had worse ozone-induced AHR, which persisted in the 4-week recovery animals. Prenatal diesel exposure combined with postnatal ozone exposure also worsened secondary alveolar crest development. We conclude that maternal inhalation of DE in pregnancy provokes a fetal inflammatory response that, combined with postnatal ozone exposure, impairs alveolar development, and causes a more severe and long-lasting AHR to ozone exposure.

  10. A Computational Investigation of Sooting Limits of Spherical Diffusion Flames

    NASA Technical Reports Server (NTRS)

    Lecoustre, V. R.; Chao, B. H.; Sunderland, P. B.; Urban, D. L.; Stocker, D. P.; Axelbaum, R. L.

    2007-01-01

    Limiting conditions for soot particle inception in spherical diffusion flames were investigated numerically. The flames were modeled using a one-dimensional, time accurate diffusion flame code with detailed chemistry and transport and an optically thick radiation model. Seventeen normal and inverse flames were considered, covering a wide range of stoichiometric mixture fraction, adiabatic flame temperature, and residence time. These flames were previously observed to reach their sooting limits after 2 s of microgravity. Sooting-limit diffusion flames with residence times longer than 200 ms were found to have temperatures near 1190 K where C/O = 0.6, whereas flames with shorter residence times required increased temperatures. Acetylene was found to be a reasonable surrogate for soot precursor species in these flames, having peak mole fractions of about 0.01.

  11. Radiative Heat Transfer and Turbulence-Radiation Interactions in a Heavy-Duty Diesel Engine

    NASA Astrophysics Data System (ADS)

    Paul, C.; Sircar, A.; Ferreyro, S.; Imren, A.; Haworth, D. C.; Roy, S.; Ge, W.; Modest, M. F.

    2016-11-01

    Radiation in piston engines has received relatively little attention to date. Recently, it is being revisited in light of current trends towards higher operating pressures and higher levels of exhaust-gas recirculation, both of which enhance molecular gas radiation. Advanced high-efficiency engines also are expected to function closer to the limits of stable operation, where even small perturbations to the energy balance can have a large influence on system behavior. Here several different spectral radiation property models and radiative transfer equation (RTE) solvers have been implemented in an OpenFOAM-based engine CFD code, and simulations have been performed for a heavy-duty diesel engine. Differences in computed temperature fields, NO and soot levels, and wall heat transfer rates are shown for different combinations of spectral models and RTE solvers. The relative importance of molecular gas radiation versus soot radiation is examined. And the influence of turbulence-radiation interactions is determined by comparing results obtained using local mean values of composition and temperature to compute radiative emission and absorption with those obtained using a particle-based transported probability density function method. DOE, NSF.

  12. Spectral Signature of Radiative Forcing by East Asian Dust-Soot Mixture

    NASA Astrophysics Data System (ADS)

    Zhu, A.; Ramanathan, V.

    2007-12-01

    The Pacific Dust Experiment (PACDEX) provides the first detailed sampling of dust-soot mixtures from the western Pacific to the eastern Pacific Ocean. The data includes down and up spectral irradiance, mixing state of dust and soot, and other aerosol properties. This study attempts to simulate the radiative forcing by dust-soot mixtures during the experimental period. The MODTRAN band model was employed to investigate the spectral signatures of solar irradiance change induced by aerosols at moderate spectral resolutions. For the short wave band (300-1100nm) used in this study, the reduction of downward irradiance at surface by aerosols greatly enhances with increasing wavelength in the UV band (300-400nm), reaches a maximum in the blue band, then gradually decreases toward the red band. In the near-IR band (700-1100nm), irradiance reduction by aerosols shows great fluctuations in the band with center wavelength at around 940nm, 820nm, 720nm, 760nm, 690nm, where the aerosol effect is overwhelmed by the water vapor and O2 absorptions. The spectral pattern of irradiance reduction varies for different aerosol species. The maximum reduction lies at around 450nm for soot, and shifting to about 490nm for East Asian mineral dust. It's worth noting that although soot aerosols reduce more irradiance than East Asian dust in the UV and blue band, the impact of dust to the irradiance exceeds that by soot at the longer wavelength band (i.e. around 550nm). The reduction of irradiance by East Asian dust (soot) in the UV band, visible band, and near-IR accounts for about 6% (10%), 56% (64%), and 38% (26%) of total irradiance reduction. As large amount of soot aerosols are involved during the long range transport of East Asian dust, the optical properties of dust aerosols are modified with different mixing state with soot, the spectral pattern of the irradiance reduction will be changed. The study of aerosol forcing at moderate spectral resolutions has the potential application for

  13. Soot climate forcing via snow and ice albedos.

    PubMed

    Hansen, James; Nazarenko, Larissa

    2004-01-13

    Plausible estimates for the effect of soot on snow and ice albedos (1.5% in the Arctic and 3% in Northern Hemisphere land areas) yield a climate forcing of +0.3 W/m(2) in the Northern Hemisphere. The "efficacy" of this forcing is approximately 2, i.e., for a given forcing it is twice as effective as CO(2) in altering global surface air temperature. This indirect soot forcing may have contributed to global warming of the past century, including the trend toward early springs in the Northern Hemisphere, thinning Arctic sea ice, and melting land ice and permafrost. If, as we suggest, melting ice and sea level rise define the level of dangerous anthropogenic interference with the climate system, then reducing soot emissions, thus restoring snow albedos to pristine high values, would have the double benefit of reducing global warming and raising the global temperature level at which dangerous anthropogenic interference occurs. However, soot contributions to climate change do not alter the conclusion that anthropogenic greenhouse gases have been the main cause of recent global warming and will be the predominant climate forcing in the future.

  14. Phototransformation rate constants of PAHs associated with soot particles.

    PubMed

    Kim, Daekyun; Young, Thomas M; Anastasio, Cort

    2013-01-15

    Photodegradation is a key process governing the residence time and fate of polycyclic aromatic hydrocarbons (PAHs) in particles, both in the atmosphere and after deposition. We have measured photodegradation rate constants of PAHs in bulk deposits of soot particles illuminated with simulated sunlight. The photodegradation rate constants at the surface (k(p)(0)), the effective diffusion coefficients (D(eff)), and the light penetration depths (z(0.5)) for PAHs on soot layers of variable thickness were determined by fitting experimental data with a model of coupled photolysis and diffusion. The overall disappearance rates of irradiated low molecular weight PAHs (with 2-3 rings) on soot particles were influenced by fast photodegradation and fast diffusion kinetics, while those of high molecular weight PAHs (with 4 or more rings) were apparently controlled by either the combination of slow photodegradation and slow diffusion kinetics or by very slow diffusion kinetics alone. The value of z(0.5) is more sensitive to the soot layer thickness than the k(p)(0) value. As the thickness of the soot layer increases, the z(0.5) values increase, but the k(p)(0) values are almost constant. The effective diffusion coefficients calculated from dark experiments are generally higher than those from the model fitting method for illumination experiments. Due to the correlation between k(p)(0) and z(0.5) in thinner layers, D(eff) should be estimated by an independent method for better accuracy. Despite some limitations of the model used in this study, the fitted parameters were useful for describing empirical results of photodegradation of soot-associated PAHs. Copyright © 2012 Elsevier B.V. All rights reserved.

  15. Phototransformation Rate Constants of PAHs Associated with Soot Particles

    PubMed Central

    Kim, Daekyun; Young, Thomas M.; Anastasio, Cort

    2013-01-01

    Photodegradation is a key process governing the residence time and fate of polycyclic aromatic hydrocarbons (PAHs) in particles, both in the atmosphere and after deposition. We have measured photodegradation rate constants of PAHs in bulk deposits of soot particles illuminated with simulated sunlight. The photodegradation rate constants at the surface (k0p), the effective diffusion coefficients (Deff), and the light penetration depths (z0.5) for PAHs on soot layers of variable thickness were determined by fitting experimental data with a model of coupled photolysis and diffusion. The overall disappearance rates of irradiated low molecular weight PAHs (with 2-3 rings) on soot particles were influenced by fast photodegradation and fast diffusion kinetics, while those of high molecular weight PAHs (with 4 or more rings) were apparently controlled by either the combination of slow photodegradation and slow diffusion kinetics or by very slow diffusion kinetics alone. The value of z0.5 is more sensitive to the soot layer thickness than the k0p value. As the thickness of the soot layer increases, the z0.5 values increase, but the k0p values are almost constant. The effective diffusion coefficients calculated from dark experiments are generally higher than those from the model fitting method for illumination experiments. Due to the correlation between k0p and z0.5 in thinner layers, Deff should be estimated by an independent method for better accuracy. Despite some limitations of the model used in this study, the fitted parameters were useful for describing empirical results of photodegradation of soot-associated PAHs. PMID:23247292

  16. Latitudinal distribution of black carbon soot in the upper troposphere and lower stratosphere

    NASA Technical Reports Server (NTRS)

    Blake, David F.; Kato, Katharine

    1995-01-01

    Black carbon soot from the upper troposphere and lower stratosphere has been systematically collected at latitudes from 90 deg N to 45 deg S. The measured latitudinal distribution of this soot at 10 to 11 km altitude is found to covary with commercial air traffic fuel use, suggesting that aircraft fuel combustion at altitude is the principal source. In addition, at latitudes where the commercial air traffic is high, measured black carbon soot values are high even at 20 km altitude, suggesting that aircraft-generated soot injected just above the tropopause may be transported to higher altitudes. During the volcanically influenced period in which these samples were collected, the number abundances, total mass, and calculated total surface area of black carbon soot are 2-3 orders of magnitude lower than similar measures of sulfuric acid aerosol. During volcanically quiescent periods, the calculated total surface area of black carbon soot aerosol is of the same order of magnitude as that of the background sulfuric acid aerosol. It appears from this comparison that black carbon soot is only capable of influencing lower stratosphere or upper troposphere chemistry during periods when the aerosol budget is not dominated by volcanic activity. It remains to determine the extent to which black carbon soot particles act as nuclei for sulfuric acid aerosol formation. However, mass balance calculations suggest that aircraft soot injected at altitude does not represent a significant source of condensation nuclei for sulfuric acid aerosols.

  17. A Quantitative Model for the Prediction of Sooting Tendency from Molecular Structure

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    St. John, Peter C.; Kairys, Paul; Das, Dhrubajyoti D.

    Particulate matter emissions negatively affect public health and global climate, yet newer fuel-efficient gasoline direct injection engines tend to produce more soot than their port-fuel injection counterparts. Fortunately, the search for sustainable biomass-based fuel blendstocks provides an opportunity to develop fuels that suppress soot formation in more efficient engine designs. However, as emissions tests are experimentally cumbersome and the search space for potential bioblendstocks is vast, new techniques are needed to estimate the sooting tendency of a diverse range of compounds. In this study, we develop a quantitative structure-activity relationship (QSAR) model of sooting tendency based on the experimental yieldmore » sooting index (YSI), which ranks molecules on a scale from n-hexane, 0, to benzene, 100. The model includes a rigorously defined applicability domain, and the predictive performance is checked using both internal and external validation. Model predictions for compounds in the external test set had a median absolute error of ~3 YSI units. An investigation of compounds that are poorly predicted by the model lends new insight into the complex mechanisms governing soot formation. Predictive models of soot formation can therefore be expected to play an increasingly important role in the screening and development of next-generation biofuels.« less

  18. Effect of Sulfuric Acid on the Uptake of Sulfur Dioxide on Soot

    NASA Astrophysics Data System (ADS)

    Slowik, J. G.; Koehler, B. G.

    2001-05-01

    The uptake of SO2 on soot may lead to the formation of sulfuric acid on the soot. The sulfuric acid then can affect the further uptake of SO2 on the soot. We are interested in the effect of submonolayer H2SO4 on the uptake of SO2. We measured the uptake of SO2 on n-hexane soot as a function SO2 pressure (10-7 to 10-4 Torr) and sulfuric acid coverage between -140\\deg and -120\\deg C. We generate sulfuric acid by adsorbing varying amounts of SO3 on soot, covering the SO3 with a thick layer of condensed H2O, and heating to 193 K to react the SO3 and H2O and to remove the excess H2O. The sulfuric acid coverage is in the range of monolayer or sub-monolayer. Adsorption of SO2 on soot with and without the sulfuric acid shows that the acid reduces the SO2 uptake by a factor of two or more. Varying the amount of acid has little effect on uptake. However, increasing the thickness of the soot substrate causes a significant increase in SO2 uptake.

  19. A Quantitative Model for the Prediction of Sooting Tendency from Molecular Structure

    DOE PAGES

    St. John, Peter C.; Kairys, Paul; Das, Dhrubajyoti D.; ...

    2017-07-24

    Particulate matter emissions negatively affect public health and global climate, yet newer fuel-efficient gasoline direct injection engines tend to produce more soot than their port-fuel injection counterparts. Fortunately, the search for sustainable biomass-based fuel blendstocks provides an opportunity to develop fuels that suppress soot formation in more efficient engine designs. However, as emissions tests are experimentally cumbersome and the search space for potential bioblendstocks is vast, new techniques are needed to estimate the sooting tendency of a diverse range of compounds. In this study, we develop a quantitative structure-activity relationship (QSAR) model of sooting tendency based on the experimental yieldmore » sooting index (YSI), which ranks molecules on a scale from n-hexane, 0, to benzene, 100. The model includes a rigorously defined applicability domain, and the predictive performance is checked using both internal and external validation. Model predictions for compounds in the external test set had a median absolute error of ~3 YSI units. An investigation of compounds that are poorly predicted by the model lends new insight into the complex mechanisms governing soot formation. Predictive models of soot formation can therefore be expected to play an increasingly important role in the screening and development of next-generation biofuels.« less

  20. New Nanotech from an Ancient Material: Chemistry Demonstrations Involving Carbon-Based Soot

    ERIC Educational Resources Information Center

    Campbell, Dean J.; Andrews, Mark J.; Stevenson, Keith J.

    2012-01-01

    Carbon soot has been known since antiquity, but has recently been finding new uses as a robust, inexpensive nanomaterial. This paper describes the superhydrophobic properties of carbon soot films prepared by combustion of candle wax or propane gas and introduces some of the optical absorption and fluorescence properties of carbon soot particles.…

  1. Soot formation in the methane oxygen and methane/oxygen/hydrogen flame

    NASA Technical Reports Server (NTRS)

    Dauerman, L.; Salser, G. E.

    1972-01-01

    The feasibility of using methane, recovered from carbon dioxide by the Sabatier-Senderens reaction, was investigated as a fuel in a reaction control engine. A problem to be avoided is the emission of soot particles. It is thought that such particles would remain in the environment of the spacecraft and, thereby, adversely affect optical sightings and possibly have an effect upon communications. The initial studies were of a practical nature. The first was the influence of the spatial arrangement of the fuel and oxygen injectors on soot formation. In the second study, inhibition of soot formation was considered. Considering the given situation, it was impractical to use an additive. However, since methanol combustion does not produce soot, and methanol can be produced from methane in situ, the possibility that methanol could act as an inhibitor was studied. In the third study, since these are restartable engines, the effect of shutdown on the rapidity of soot formation was studied.

  2. Structure of the Soot Growth Region of Laminar Premixer Methane/Oxygen Flames

    NASA Technical Reports Server (NTRS)

    Xu, F.; Faeth, G. M.

    1999-01-01

    Soot is a dominant feature of hydrocarbon/air flames, affecting their reaction mechanisms and structure. As a result, soot processes affect capabilities for computational combustion as well as predictions of flame radiation and pollution emissions. Motivated by these observations, the present investigation extended past work on soot growth in laminar premixed flames, seeking to evaluate model predictions of flame structure. Xu et al. report direct measurements of soot residence times, soot concentrations, soot structure, gas temperatures and gas compositions for premixed flames similar to those studied by Harris and Weiner and Ramer et al. respectively. It was found that predictions of major stable gas species concentrations based on mechanisms of Leung and Lindstedt and Frenklach and coworkers, were in good agreement with the measurements. The results were also used to evaluate the hydrogen-abstraction/carbon-addition (HACA) soot growth mechanisms of Frenklach and coworkers and Colket and Hall. It was found that these mechanisms were effective using quite reasonable correlations for the steric factors appearing in the theories. The successful evaluation of the HACA mechanism of soot growth in Refs. 1 and 2 is encouraging but one aspect of this evaluation is a concern. In particular, H-atom concentrations play a crucial role in the HACA mechanism and it was necessary to estimate these concentrations because they were not measured directly. These estimates were made assuming local thermodynamic equilibrium between H, and H based on measured temperatures and H2 concentrations and the equilibrium constant data of Kee et al.. This approach was justified by the flame structure predictions; nevertheless, direct evaluation of equilibrium estimates of H-atom concentrations in the soot growth regions of laminar premixed flames is needed to provide more convincing proof of this behavior. Thus, the objective of the present investigation was to complete new measurements of the

  3. Effect of alcohol addition on shock-initiated formation of soot from benzene

    NASA Technical Reports Server (NTRS)

    Frenklach, Michael; Yuan, Tony

    1988-01-01

    Soot formation in benzene-methanol and benzene-ethanol argon-diluted mixtures was studied behind reflected shock waves by monitoring the attenuation of an He-Ne laser beam. The experiments were performed at temperatures 1580-2250 K, pressures 2.0-3.0 bar, and total carbon atom concentrations (2.0-2.7) x 10 to the 17th atoms/cu cm. The results obtained indicate that the addition of alcohol suppresses the formation of soot from benzene at all temperatures, and that the reduction in soot yields is increased with the amount of alcohol added. The analysis of the results indicates that the suppression effect is probably due to the oxidation of soot and soot precursors by OH and the removal of hydrogen atoms by alcohol and water molecules.

  4. The Ice Nucleation Activity of Surface Modified Soot

    NASA Astrophysics Data System (ADS)

    Häusler, Thomas; Witek, Lorenz; Felgitsch, Laura; Hitzenberger, Regina; Grothe, Hinrich

    2017-04-01

    The ice nucleation efficiency of many important atmospheric particles remains poorly understood. Since soot is ubiquitous in the Earth's troposphere, they might have the potential to significantly impact the Earth's climate (Finlayson-Pitts and Pitts, 2000; Seinfeld and Pandis, 1998). Here we present the ice nucleation activity (INA) in immersion freezing mode of different types of soot. Therefor a CAST (combustion aerosol standard) generator was used to produce different kinds of soot samples. The CAST generator combusts a propane-air-mixture and deposits thereby produced soot on a polyvinyl fluoride filter. By varying the propane to air ratio, the amount of organic portion of the soot can be varied from black carbon (BC) with no organic content to brown carbon (BrC) with high organic content. To investigate the impact of functional sites of ice nuclei (IN), the soot samples were exposed to NO2 gas for a certain amount of time (30 to 360 minutes) to chemically modify the surface. Immersion freezing experiments were carried out in a unique reaction gadget. In this device a water-in-oil suspension (with the soot suspended in the aqueous phase) was cooled till the freezing point and was observed through a microscope (Pummer et al., 2012; Zolles et al., 2015) It was found that neither modified nor unmodified BC shows INA. On the contrary, unmodified BrC shows an INA at -32˚ C, which can be increased up to -20˚ C. The INA of BrC depends on the duration of NO2- exposure. To clarify the characteristics of the surface modifications, surface sensitive analysis like infrared spectroscopy and X-ray photoelectron spectroscopy were carried out. Finlayson-Pitts, B. J. and Pitts, J. N. J.: Chemistry of the Upper and Lower Atmosphere, Elsevier, New York, 2000. Pummer, B. G., Bauer, H., Bernardi, J., Bleicher, S., and Grothe, H.: Suspendable macromolecules are responsible for ice nucleation activity of birch and conifer pollen, Atmos Chem Phys, 12, 2541-2550, 2012. Seinfeld, J

  5. Uptake of HNO3 on hexane and aviation kerosene soots.

    PubMed

    Talukdar, Ranajit K; Loukhovitskaya, Ekaterina E; Popovicheva, Olga B; Ravishankara, A R

    2006-08-10

    The uptake of HNO(3) on aviation kerosene (TC-1) soot was measured as a function of temperature (253-295 K) and the partial pressure of HNO(3), and the uptake of HNO(3) on hexane soot was studied at 295 K and over a limited partial pressure of HNO(3). The HNO(3) uptake was mostly reversible and did not release measurable amounts of gas-phase products such as HONO, NO(3), NO(2) or N(2)O(5). The heat of adsorption of HNO(3) on soot was dependent on the surface coverage. The isosteric heats of adsorption, Delta(0)H(isosteric), were determined as a function of coverage. Delta(0)H(isosteric) values were in the range -16 to -13 kcal mol(-1). The heats of adsorption decrease with increasing coverage. The adsorption data were fit to Freundlich and to Langmuir-Freundlich isotherms. The heterogeneity parameter values were close to 0.5, which suggested that a HNO(3) molecule can occupy two sites on the surface with or without being dissociated and that the soot surface could be nonuniform. Surface FTIR studies on the interaction of soot with HNO(3) did not reveal formation of any minor product such as organic nitrate or nitro compound on the soot surface. Using our measured coverage, we calculate that the partitioning of gas-phase nitric acid to black carbon aerosol is not a significant loss process of HNO(3) in the atmosphere.

  6. Soot superaggregates from flaming wildfires and their direct radiative forcing.

    PubMed

    Chakrabarty, Rajan K; Beres, Nicholas D; Moosmüller, Hans; China, Swarup; Mazzoleni, Claudio; Dubey, Manvendra K; Liu, Li; Mishchenko, Michael I

    2014-07-01

    Wildfires contribute significantly to global soot emissions, yet their aerosol formation mechanisms and resulting particle properties are poorly understood and parameterized in climate models. The conventional view holds that soot is formed via the cluster-dilute aggregation mechanism in wildfires and emitted as aggregates with fractal dimension Df ≈ 1.8 mobility diameter Dm ≤ 1 μm, and aerodynamic diameter Da ≤ 300 nm. Here we report the ubiquitous presence of soot superaggregates (SAs) in the outflow from a major wildfire in India. SAs are porous, low-density aggregates of cluster-dilute aggregates with characteristic Df ≈ 2.6, Dm > 1 μm, and Da ≤ 300 nm that form via the cluster-dense aggregation mechanism. We present additional observations of soot SAs in wildfire smoke-laden air masses over Northern California, New Mexico, and Mexico City. At 550 nm wavelength, [corrected] we estimate that SAs contribute, per unit optical depth, up to 35% less atmospheric warming than freshly-emitted (D(f) ≈ 1.8) [corrected] aggregates, and ≈90% more warming than the volume-equivalent spherical soot particles simulated in climate models.

  7. Soot Oxidation in Hydrocarbon/Air Diffusion Flames at Atmospheric Pressure. Appendix K

    NASA Technical Reports Server (NTRS)

    Xu, F.; El-Leathy, A. M.; Faeth, G. M.; Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

    2001-01-01

    Soot oxidation was studied experimentally in laminar hydrocarbon/air diffusion flames at atmospheric pressure. Measurements were carried out along the axes of round jets burning in coflowing air considering acetylene, ethylene, propylene and propane as fuels. Measurements were limited to the initial stages of soot oxidation (carbon consumption less than 70%) where soot oxidation mainly occurs at the surface of primary soot particles. The following properties were measured as a function of distance above the burner exit: soot concentrations by deconvoluted laser extinction, soot temperatures by deconvoluted multiline emission, soot structure by thermophoretic sampling and analysis using Transmission Electron Microscopy (TEM), concentrations of stable major gas species (N2, H2O, H2, O2, CO, CO2, CH4, C2H2,C2H4, C2H6, C3H6, and C3H8) by sampling and gas chromatography, concentrations of some radical species (H, OH, O) by the deconvoluted Li/LiOH atomic absorption technique and flow velocities by laser velocimetry. It was found that soot surface oxidation rates are not particularly affected by fuel type for laminar diffusion flames and are described reasonably well by the OH surface oxidation mechanism with a collision efficiency of 0.10, (standard deviation of 0.07) with no significant effect of fuel type in this behavior; these findings are in good agreement with the classical laminar premixed flame measurements of Neoh et al. Finally, direct rates of surface oxidation by O2 were small compared to OH oxidation for present conditions, based on estimated O2 oxidation rates due to Nagle and Strickland-Constable (1962), because soot oxidation was completed near the flame sheet where O2 concentrations were less than 1.2% by volume.

  8. Multi-Wavelength Measurement of Soot Optical Properties: Influence of Non-Absorbing Coatings

    NASA Astrophysics Data System (ADS)

    Freedman, Andrew; Renbaum-Wollf, Lindsay; Forestieri, Sara; Lambe, Andrew; Cappa, Christopher; Davidovits, Paul; Onasch, Timothy

    2015-04-01

    Soot, a product of incomplete combustion, plays an important role in the earth's climate system through the absorption and scattering of solar radiation. Important in quantifying the direct radiative impacts of soot in climate models, and specifically of black carbon (BC), is the assumed BC refractive index and shape-dependent interaction of light with BC particles. The latter assumption carries significant uncertainty because BC particles are fractal-like, being agglomerates of smaller (20-40 nm) spherules, yet many optical models such as Mie theory in particular, typically assume a spherical particle morphology. It remains unclear under what conditions this is an acceptable assumption. To investigate the ability of various optical models to reproduce observed BC optical properties, we obtained measurements of light absorption, scattering and extinction coefficients and thus single scattering albedo (SSA) of size-resolved soot particles. Measurements were made on denuded soot particles produced using both methane and ethylene as fuels. In addition, these soot particles were coated with dioctyl sebacate or sulfuric acid and the enhancement in the apparent mass absorption coefficient determined. Extinction and absorption were measured using a dual cavity ringdown photoacoustic spectrometer (CRD-PAS) at 405 nm and 532 nm. Scattering and extinction were measured using a CAPS PMssa single scattering albedo monitor (Aerodyne) at 630 nm. Soot particle mass was quantified using a centrifugal particle mass analyzer (CPMA, Cambustion), mobility size with a scanning mobility particle sizer (SMPS, TSI) and soot concentration with a CPC (Brechtel). The results will be interpreted in light of both Mie theory which assumes spherical and uniform particles and Rayleigh-Debye-Gans (RDG) theory, which assumes that the absorption properties of soot are dictated by the individual spherules. For denuded soot, effective refractive indices will be determined.

  9. Soot formation in shock-tube pyrolysis and oxidation of vinylacetylene

    NASA Technical Reports Server (NTRS)

    Frenklach, M.; Yuan, T.; Ramachandra, M. K.

    1990-01-01

    Soot formation in vinylacetylene, and vinylacetylene-oxygen argon-diluted mixtures was studied behind reflected shock waves by monitoring the attenuation of a 632.8-nm He-Ne laser beam. The experiments were performed at temperatures of 1600-2500 K, pressures of 2.08-3.09 bar, and total carbon atom concentrations of (1.99-2.05) x 10 to the 17th atoms/cu cm. The experimental results obtained in pyrolysis of vinylacetylene are similar to those of acetylene, both in the order of magnitude of the soot yield and the shape of its temperature dependence. The addition of oxygen to vinylacetylene shifts the soot bell to lower temperature and, distinct from all other hydrocarbons studied in this laboratory, accelerates the production of soot with reaction time. The experimental results are interpreted in terms of possible chemical reaction.

  10. Aggregates and Superaggregates of Soot with Four Distinct Fractal Morphologies

    NASA Technical Reports Server (NTRS)

    Sorensen, C. M.; Kim, W.; Fry, D.; Chakrabarti, A.

    2004-01-01

    Soot formed in laminar diffusion flames of heavily sooting fuels evolves through four distinct growth stages which give rise to four distinct aggregate fractal morphologies. These results were inferred from large and small angle static light scattering from the flames, microphotography of the flames, and analysis of soot sampled from the flames. The growth stages occur approximately over four successive orders of magnitude in aggregate size. Comparison to computer simulations suggests that these four growth stages involve either diffusion limited cluster aggregation or percolation in either three or two dimensions.

  11. Evolution of Soot Particle Morphology and Mixing State in the Atmosphere

    NASA Astrophysics Data System (ADS)

    Mazzoleni, C.; China, S.; Sharma, N.; Gorkowski, K.; Dubey, M.; Aiken, A. C.; Zaveri, R. A.; Salvadori, N.; Chakrabarty, R. K.; Moosmuller, H.; Onasch, T. B.; Herndon, S.; Williams, L. R.; Liu, S.; Dzepina, K.; Helmig, D.; Hueber, J.; Fialho, P. J.; Mazzoleni, L. R.; kumar, S.; Dziobak, M.; Wright, K.

    2013-12-01

    Soot particles (aka black carbon) impact the environment and climate by affecting Earth's radiation balance, cloud microphysics, and atmospheric chemistry. The complex morphology and mixing state of soot particles influence their optical properties and therefore their radiative forcing, the particles' transport, lifecycle, and heterogeneous chemistry. How soot morphology and mixing state alter during transport from the source to remote areas is still not well understood. While aging, soot particles can change shape, oxidize and mix, and become coated by organic and inorganic materials. In this study, we investigate the morphological and mixing state evolution of single soot particles in different stages of their 'life' in the atmosphere. This analysis will include an overview of several samples collected in various locations and atmospheric conditions: 1) particles freshly emitted near freeway on-ramps in Southern Michigan (USA); 2) particles emitted in two biomass burning events in New Mexico (USA), one close to the sampling location and another hundreds of miles away; 3) particles in the urban atmosphere of Mexico City and in the uplifted boundary layer captured on the top of the Pico de Tres Padres Mountain (on the north edge of Mexico City); 4) particles collected in the Sacramento urban area and the Sierra Nevada foothills (CA, USA); 5) particles collected in Detling (UK), and mostly transported from London, and 6) long-range transported particles in the free troposphere and collected at the Pico Mountain Observatory, located near the top of the Pico Volcano in the Azores (Portugal). We analyzed a large number of individual particles using electron microscopy and X-ray spectroscopy followed by image analysis. The projected structural properties of soot particles were characterized using size (maximum length, maximum width, and area equivalent diameter) and shape descriptors (e.g., aspect ratio, roundness, and convexity). The particle mass-fractal dimensions

  12. Refractive indices at visible wavelengths of soot emitted from buoyant turbulent diffusion flames

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wu, J.S.; Krishnan, S.K.; Faeth, G.M.

    1996-11-01

    Measurements of the optical properties of soot, emphasizing refractive indices, are reported for visible wavelengths. The experiments considered soot in the fuel-lean (overfire) region of buoyant turbulent diffusion flames in the long residence time regime where soot properties are independent of position in the overfire region and residence time. Flames fueled with acetylene, propylene, ethylene and propane burning in still air provided a range of soot physical and structure properties. Measurements included soot composition, density, structure, gravimetric volume fraction, scattering properties and absorption properties. These data were analyzed to find soot fractal dimensions, refractive indices and dimensionless extinction coefficients, assumingmore » Rayleigh-Debye-Gans scattering for polydisperse mass fractal aggregates (RDG-PFA theory). RDG-PFA theory was successfully evaluated, based on measured scattering patterns. Soot fractal dimensions were independent of both fuel type and wavelength, yielding a mean value of 1.77 with a standard deviation of 0.04. Refractive indices were independent of fuel type within experimental uncertainties and were in reasonably good agreement with earlier measurements for soot in the fuel-lean region of diffusion flames due to Dalzell and Sarofim (1969). Dimensionless extinction coefficients were independent of both fuel type and wavelength, yielding a mean value of 5.1 with a standard deviation of 0.5, which is lower than earlier measurements for reasons that still must be explained.« less

  13. Laser-saturated fluorescence measurements in laminar sooting diffusion flames

    NASA Technical Reports Server (NTRS)

    Wey, Changlie

    1993-01-01

    The hydroxyl radical is known to be one of the most important intermediate species in the combustion processes. The hydroxyl radical has also been considered a dominant oxidizer of soot particles in flames. In this investigation the hydroxyl concentration profiles in sooting diffusion flames were measured by the laser-saturated fluorescence (LSF) method. The temperature distributions in the flames were measured by the two-line LSF technique and by thermocouple. In the sooting region the OH fluorescence was too weak to make accurate temperature measurements. The hydroxyl fluorescence profiles for all four flames presented herein show that the OH fluorescence intensities peaked near the flame front. The OH fluorescence intensity dropped sharply toward the dark region of the flame and continued declining to the sooting region. The OH fluorescence profiles also indicate that the OH fluorescence decreased with increasing height in the flames for all flames investigated. Varying the oxidizer composition resulted in a corresponding variation in the maximum OH concentration and the flame temperature. Furthermore, it appears that the maximum OH concentration for each flame increased with increasing flame temperature.

  14. Development of a semitransparent ceramic heat-insulation for an eco-friendly combustion chamber of Low-Heat-Rejection diesel

    NASA Astrophysics Data System (ADS)

    Merzlikin, V. G.; Gutierrez, M. O.; Makarov, A. R.; Bekaev, A. A.; Bystrov, A. V.; Zagumennov, F. A.

    2018-02-01

    Efficiency of diesel has been studied using well-known types of the ceramic heat-insulating HICs- or thermal barrier TBCs-coatings. This problem is relevant for a high-speed diesel combustion chamber in which intensive radiant component (near IR) reaches ~50% within total thermal flux. Therefore, in their papers the authors offered new concept of study these materials as semitransparent SHICs-, STBCs-coatings. On the Mie scattering theory the effect of selection of the specific structural composition and porosity of coatings on the variation of their optical parameters is considered. Conducted spectrophotometric modeling of the volume-absorbed radiant energy by the coating had determined their acceptable temperature field. For rig testings coated piston using selected SHIC (PSZ-ceramic ZrO2+8%Y2O3) with a calculated optimum temperature gradient was chosen. A single cylinder experimental tractor diesel was used. At rotation frequency n > 2800 rpm the heat losses were no more than 0.2 MW/m2. Executed testings showed ~2-3% lower specific fuel consumption in contrast the diesel with uncoated piston. Effective power and drive torque were ~2-5% greater. The authors have substantiated the growth the efficiency of this Low-Heat-Rejection (LHR) diesel due to the known effect of soot deposition gasification at high speed.Then unpolluted semitransparent ceramic thermal insulation forms the required thermoradiation fields and temperature profiles and can affect regulation of heat losses and reduction of primarily nitrogen dioxide generation.

  15. Development of an on-line exposure system to determine freshly produced diesel engine emission-induced cellular effects.

    PubMed

    Oostingh, Gertie J; Papaioannou, Eleni; Chasapidis, Leonidas; Akritidis, Theofylaktos; Konstandopoulos, Athanasios G; Duschl, Albert

    2013-09-01

    Diesel engine emission particle filters are often placed at exhaust outlets to remove particles from the exhaust. The use of filters results in the exposure to a reduced number of nanometer-sized particles, which might be more harmful than the exposure to a larger number of micrometer-sized particles. An in vitro exposure system was established to expose human alveolar epithelial cells to freshly generated exhaust. Computer simulations were used to determine the optimal flow characteristics and ensure equal exposure conditions for each well of a 6-well plate. A selective particle size sampler was used to continuously deliver diesel soot particles with different particle size distributions to cells in culture. To determine, whether the system could be used for cellular assays, alterations in cytokine production and cell viability of human alveolar A549 cells were determined after 3h on-line exposure followed by a 21-h conventional incubation period. Data indicated that complete diesel engine emission slightly affected pre-stimulated cells, but naive cells were not affected. The fractions containing large or small particles never affected the cells. The experimental set-up allowed a reliable exposure of the cells to the complete exhaust fraction or to the fractions containing either large or small diesel engine emission particles. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. Measurements of soot formation and hydroxyl concentration in near critical equivalence ratio premixed ethylene flame

    NASA Technical Reports Server (NTRS)

    Inbody, Michael Andrew

    1993-01-01

    The testing and development of existing global and detailed chemical kinetic models for soot formation requires measurements of soot and radical concentrations in flames. A clearer understanding of soot particle inception relies upon the evaluation and refinement of these models in comparison with such measurements. We present measurements of soot formation and hydroxyl (OH) concentration in sequences of flat premixed atmospheric-pressure C2H4/O2/N2 flames and 80-torr C2H4/O2 flames for a unique range of equivalence ratios bracketting the critical equivalence ratio (phi(sub c)) and extending to more heavily sooting conditions. Soot volume fraction and number density profiles are measured using a laser scattering-extinction apparatus capable of resolving a 0.1 percent absorption. Hydroxyl number density profiles are measured using laser-induced fluorescence (LIF) with broadband detection. Temperature profiles are obtained from Rayleigh scattering measurements. The relative volume fraction and number density profiles of the richer sooting flames exhibit the expected trends in soot formation. In near-phi(sub c) visibility sooting flames, particle scattering and extinction are not detected, but an LIF signal due to polycyclic aromatic hydrocarbons (PAH's) can be detected upon excitation with an argon-ion laser. A linear correlation between the argon-ion LIF and the soot volume fraction implies a common mechanistic source for the growth of PAH's and soot particles. The peak OH number density in both the atmospheric and 80-torr flames declines with increasing equivalence ratio, but the profile shape remains unchanged in the transition to sooting, implying that the primary reaction pathways for OH remain unchanged over this transition. Chemical kinetic modeling is demonstrated by comparing predictions using two current reaction mechanisms with the atmospheric flame data. The measured and predicted OH number density profiles show good agreement. The predicted benzene

  17. Discriminating Bio-aerosols from Non-Bio-aerosols in Real-Time by Pump-Probe Spectroscopy

    PubMed Central

    Sousa, Gustavo; Gaulier, Geoffrey; Bonacina, Luigi; Wolf, Jean-Pierre

    2016-01-01

    The optical identification of bioaerosols in the atmosphere and its discrimination against combustion related particles is a major issue for real-time, field compatible instruments. In the present paper, we show that by embedding advanced pump-probe depletion spectroscopy schemes in a portable instrument, it is possible to discriminate amino acid containing airborne particles (bacteria, humic particles, etc.) from poly-cyclic aromatic hydrocarbon containing combustion particles (Diesel droplets, soot, vehicle exhausts) with high selectivity. Our real-time, multi-modal device provides, in addition to the pump-probe depletion information, fluorescence spectra (over 32 channels), fluorescence lifetime and Mie scattering patterns of each individually flowing particle in the probed air. PMID:27619546

  18. Discriminating Bio-aerosols from Non-Bio-aerosols in Real-Time by Pump-Probe Spectroscopy

    NASA Astrophysics Data System (ADS)

    Sousa, Gustavo; Gaulier, Geoffrey; Bonacina, Luigi; Wolf, Jean-Pierre

    2016-09-01

    The optical identification of bioaerosols in the atmosphere and its discrimination against combustion related particles is a major issue for real-time, field compatible instruments. In the present paper, we show that by embedding advanced pump-probe depletion spectroscopy schemes in a portable instrument, it is possible to discriminate amino acid containing airborne particles (bacteria, humic particles, etc.) from poly-cyclic aromatic hydrocarbon containing combustion particles (Diesel droplets, soot, vehicle exhausts) with high selectivity. Our real-time, multi-modal device provides, in addition to the pump-probe depletion information, fluorescence spectra (over 32 channels), fluorescence lifetime and Mie scattering patterns of each individually flowing particle in the probed air.

  19. Discriminating Bio-aerosols from Non-Bio-aerosols in Real-Time by Pump-Probe Spectroscopy.

    PubMed

    Sousa, Gustavo; Gaulier, Geoffrey; Bonacina, Luigi; Wolf, Jean-Pierre

    2016-09-13

    The optical identification of bioaerosols in the atmosphere and its discrimination against combustion related particles is a major issue for real-time, field compatible instruments. In the present paper, we show that by embedding advanced pump-probe depletion spectroscopy schemes in a portable instrument, it is possible to discriminate amino acid containing airborne particles (bacteria, humic particles, etc.) from poly-cyclic aromatic hydrocarbon containing combustion particles (Diesel droplets, soot, vehicle exhausts) with high selectivity. Our real-time, multi-modal device provides, in addition to the pump-probe depletion information, fluorescence spectra (over 32 channels), fluorescence lifetime and Mie scattering patterns of each individually flowing particle in the probed air.

  20. Modeling Soot Oxidation and Gasification with Bayesian Statistics

    DOE PAGES

    Josephson, Alexander J.; Gaffin, Neal D.; Smith, Sean T.; ...

    2017-08-22

    This paper presents a statistical method for model calibration using data collected from literature. The method is used to calibrate parameters for global models of soot consumption in combustion systems. This consumption is broken into two different submodels: first for oxidation where soot particles are attacked by certain oxidizing agents; second for gasification where soot particles are attacked by H 2O or CO 2 molecules. Rate data were collected from 19 studies in the literature and evaluated using Bayesian statistics to calibrate the model parameters. Bayesian statistics are valued in their ability to quantify uncertainty in modeling. The calibrated consumptionmore » model with quantified uncertainty is presented here along with a discussion of associated implications. The oxidation results are found to be consistent with previous studies. Significant variation is found in the CO 2 gasification rates.« less

  1. Modeling Soot Oxidation and Gasification with Bayesian Statistics

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Josephson, Alexander J.; Gaffin, Neal D.; Smith, Sean T.

    This paper presents a statistical method for model calibration using data collected from literature. The method is used to calibrate parameters for global models of soot consumption in combustion systems. This consumption is broken into two different submodels: first for oxidation where soot particles are attacked by certain oxidizing agents; second for gasification where soot particles are attacked by H 2O or CO 2 molecules. Rate data were collected from 19 studies in the literature and evaluated using Bayesian statistics to calibrate the model parameters. Bayesian statistics are valued in their ability to quantify uncertainty in modeling. The calibrated consumptionmore » model with quantified uncertainty is presented here along with a discussion of associated implications. The oxidation results are found to be consistent with previous studies. Significant variation is found in the CO 2 gasification rates.« less

  2. Determination of polycyclic aromatic hydrocarbons in kerosene and bio-kerosene soot.

    PubMed

    Andrade-Eiroa, Auréa; Leroy, Valérie; Dagaut, Philippe; Bedjanian, Yuri

    2010-03-01

    Here we report a new, efficient and reliable analytical methodology for sensitive and selective quantification of Polycyclic Aromatic Hydrocarbons (PAHs) in soot samples. The methodology developed is based on ultrasonic extraction of the soot-bound PAHs into small volumes of acetonitrile, purification of the extracts through C(18) Solid Phase Extraction (SPE) cartridges and analysis by Reverse Phase Liquid Chromatography (RPLC) with UV and fluorimetric detection. For the first time, we report the convenience of adapting the SPE procedure to the nature of the soot samples. As a matter of fact, extracts containing high percentage of unpolar material are recommended to be cleaned with acetone, whereas extracts poor in unpolar compounds can be efficiently cleaned with methanol. The method was satisfactorily applied to kerosene and bio-kerosene soot from atmospheric open diffusion flames (pool fires) and premixed flames achieving Quantification and Detection limits in the range ng mg(-1) soot and recoveries about 90% for most of the PAHs studied. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

  3. Sooting Limits Of Diffusion Flames With Oxygen-Enriched Air And Diluted Fuel

    NASA Technical Reports Server (NTRS)

    Sunderland, P. B.; Urban, D. L.; Stocker, D. P.; Chao, B. H.; Axelbaum, R. L.

    2003-01-01

    Oxygen-enhanced combustion permits certain benefits and flexibility that are not otherwise available in the design of practical combustors, as discussed by Baukal. The cost of pure and enriched oxygen has declined to the point that oxygen-enhanced combustion is preferable to combustion in air for many applications. Carbon sequestration is greatly facilitated by oxygen enrichment because nitrogen can be eliminated from the product stream. For example, when natural gas (or natural gas diluted with CO2) is burned in pure oxygen, the only significant products are water and CO2. Oxygen-enhanced combustion also has important implications for soot formation, as explored in this work. We propose that soot inception in nonpremixed flames requires a region where C/O ratio, temperature, and residence time are above certain critical values. Soot does not form at low temperatures, with the threshold in nonpremixed flames ranging from about 1250-1650 K, a temperature referred to here as the critical temperature for soot inception, Tc. Soot inception also can be suppressed when residence time is short (equivalently, when the strain rate in counterflow flames is high). Soot induction times of 0.8-15 ms were reported by Tesner and Shurupov for acetylene/nitrogen mixtures at 1473 K. Burner stabilized spherical microgravity flames are employed in this work for two main reasons. First, this configuration offers unrestricted control over convection direction. Second, in steady state these flames are strain-free and thus can yield intrinsic sooting limits in diffusion flames, similar to the way past work in premixed flames has provided intrinsic values of C/O ratio associated with soot inception limits.

  4. Soot Superaggregates from Flaming Wildfires and Their Direct Radiative Forcing

    NASA Technical Reports Server (NTRS)

    Chakrabarty, Rajan K.; Beres, Nicholas D.; Moosmuller,Hans; China, Swarup; Mazzoleni, Claudio; Dubey, Manvendra K.; Liu, Li; Mishchenko, Michael I.

    2014-01-01

    Wildfires contribute significantly to global soot emissions, yet their aerosol formation mechanisms and resulting particle properties are poorly understood and parameterized in climate models. The conventional view holds that soot is formed via the cluster-dilute aggregation mechanism in wildfires and emitted as aggregates with fractal dimension D(sub f) approximately equals 1.8 mobility diameter D(sub m) (is) less than or equal to 1 micron, and aerodynamic diameter D(sub a) (is) less than or equal to 300 nm. Here we report the ubiquitous presence of soot superaggregates (SAs) in the outflow from a major wildfire in India. SAs are porous, low-density aggregates of cluster-dilute aggregates with characteristic D(sub f) approximately equals 2.6,D(sub m) (is) greater than 1 micron, and D(sub a) is less than or equal to 300 nm that form via the cluster-dense aggregation mechanism.We present additional observations of soot SAs in wildfire smoke-laden air masses over Northern California, New Mexico, and Mexico City. We estimate that SAs contribute, per unit optical depth, up to 35% less atmospheric warming than freshly-emitted (D(sub f) approximately equals 1.8) aggregates, and approximately equals 90% more warming than the volume-equivalent spherical soot particles simulated in climate models.

  5. SUPPRESSION OF BASAL AND CYTOKINE INDUCED EXPRESSION OF ANTIGEN PRESENTATION MARKERS ON MOUSE LUNG EPITHELIAL CELLS EXPOSED TO DIESEL EXHAUST PARTICLES.

    EPA Science Inventory

    Diesel exhaust particles (DEP) constitute a significant component of airborne particulates in urban environment. Exposure to DEP is known to enhance susceptibility to viral and bacterial infections. We hypothesized that DEP could partially exert its effect on disease susceptibili...

  6. Isotopic Tracing of Fuel Components in Particulate Emissions from Diesel Engines using Accelerator Mass Spectrometry (AMS)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Buchholz, B A; Mueller, C J; Garbak, J.

    2001-08-02

    Accelerator mass spectrometry (AMS) is an isotope-ratio measurement technique developed in the late 1970s for tracing long-lived radioisotopes (e.g., {sup 14}C half life = 5760 y). The technique counts individual nuclei rather than waiting for their radioactive decay, allowing measurement of more than 100 low-level {sup 14}C samples per day (Vogel et al, 1995). The LLNL AMS system is shown in Fig.1. The contemporary quantity of {sup 14}C in living things ({sup 14}C/C = 1.2 x 10{sup -12} or 110 fmol {sup 14}C/ g C) is highly elevated compared to the quantity of {sup 14}C in petroleum-derived products. This isotopicmore » elevation is sufficient to trace the fate of bio-derived fuel components in the emissions of an engine without the use of radioactive materials. If synthesis of a fuel component from biologically-derived source material is not feasible, another approach is to purchase {sup 14}C-labeled material (e.g., dibutyl maleate (DBM)) and dilute it with petroleum-derived material to yield a contemporary level of {sup 14}C. In each case, the virtual absence of {sup 14}C in petroleum based fuels gives a very low {sup 14}C background that makes this approach to tracing fuel components practical. Regulatory pressure to significantly reduce the particulate emissions from diesel engines is driving research into understanding mechanisms of soot formation. If mechanisms are understood, then combustion modeling can be used to evaluate possible changes in fuel formulation and suggest possible fuel components that can improve combustion and reduce PM emissions. The combustion paradigm assumes that large molecules break down into small components and then build up again during soot formation. AMS allows us to label specific fuel components, including oxygenates, trace the carbon atoms, and test this combustion modeling paradigm. Volatile and non-volatile organic fractions (VOF, NVOF) in the PM can be further separated. The VOF of the PM can be oxidized with catalysts in

  7. Hydrodynamic Suppression of Soot Formation in Laminar Coflowing Jet Diffusion Flames. Appendix C

    NASA Technical Reports Server (NTRS)

    Dai, Z.; Faeth, G. M.; Yuan, Z.-G. (Technical Monitor); Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

    2000-01-01

    Effects of flow (hydrodynamic) properties on limiting conditions for soot-free laminar non-premixed hydrocarbon/air flames (called laminar soot-point conditions) were studied, emphasizing non-buoyant laminar coflowing jet diffusion flames. Effects of air/fuel-stream velocity ratios were of particular interest; therefore, the experiments were carried out at reduced pressures to minimize effects of flow acceleration due to the intrusion of buoyancy. Test conditions included reactant temperatures of 300 K; ambient pressures of 3.7-49 8 kPa; methane-, acetylene-, ethylene-, propane-, and methane-fueled flames burning in coflowing air with fuel-port diameters of 1.7, 3.2, and 6.4 mm, fuel jet Reynolds numbers of 18-121; air coflow velocities of 0-6 m/s; and air/fuel-stream velocity ratios of 0.003-70. Measurements included laminar soot-point flame lengths, laminar soot-point fuel flow rates, and laminar liftoff conditions. The measurements show that laminar soot-point flame lengths and fuel flow rates can be increased, broadening the range of fuel flow rates where the flames remain soot free, by increasing air/fuel-stream velocity ratios. The mechanism of this effect involves the magnitude and direction of flow velocities relative to the flame sheet where increased air/fuel-stream velocity ratios cause progressive reduction of flame residence times in the fuel-rich soot-formation region. The range of soot-free conditions is limited by both liftoff, particularly at low pressures, and the intrusion of effects of buoyancy on effective air/fuel-stream velocity ratios, particularly at high pressures. Effective correlations of laminar soot- and smoke-point flame lengths were also found in terms of a corrected fuel flow rate parameter, based on simplified analysis of laminar jet diffusion flame structure. The results show that laminar smoke-point flame lengths in coflowing air environments are roughly twice as long as soot-free (blue) flames under comparable conditions due to

  8. Quantitative characterization of steady and time-varying, sooting, laminar diffusion flames using optical techniques

    NASA Astrophysics Data System (ADS)

    Connelly, Blair C.

    In order to reduce the emission of pollutants such as soot and NO x from combustion systems, a detailed understanding of pollutant formation is required. In addition to environmental concerns, this is important for a fundamental understanding of flame behavior as significant quantities of soot lower local flame temperatures, increase overall flame length and affect the formation of such temperature-dependent species as NOx. This problem is investigated by carrying out coupled computational and experimental studies of steady and time-varying sooting, coflow diffusion flames. Optical diagnostic techniques are a powerful tool for characterizing combustion systems, as they provide a noninvasive method of probing the environment. Laser diagnostic techniques have added advantages, as systems can be probed with high spectral, temporal and spatial resolution, and with species selectivity. Experimental soot volume fractions were determined by using two-dimensional laser-induced incandescence (LII), calibrated with an on-line extinction measurement, and soot pyrometry. Measurements of soot particle size distributions are made using time-resolved LII (TR-LII). Laser-induced fluorescence measurements are made of NO and formaldehyde. These experimental measurements, and others, are compared with computational results in an effort to understand and model soot formation and to examine the coupled relationship of soot and NO x formation.

  9. Investigation of detailed kinetic scheme performance on modelling of turbulent non-premixed sooting flames

    NASA Astrophysics Data System (ADS)

    Yunardi, Y.; Darmadi, D.; Hisbullah, H.; Fairweather, M.

    2011-12-01

    This paper presents the results of an application of a first-order conditional moment closure (CMC) approach coupled with a semi-empirical soot model to investigate the effect of various detailed combustion chemistry schemes on soot formation and destruction in turbulent non-premixed flames. A two-equation soot model representing soot particle nucleation, growth, coagulation and oxidation, was incorporated into the CMC model. The turbulent flow-field of both flames is described using the Favre-averaged fluid-flow equations, applying a standard k-ɛ turbulence model. A number of five reaction kinetic mechanisms having 50-100 species and 200-1000 elementary reactions called ABF, Miller-Bowman, GRI-Mech3.0, Warnatz, and Qin were employed to study the effect of combustion chemistry schemes on soot predictions. The results showed that of various kinetic schemes being studied, each yields similar accuracy in temperature prediction when compared with experimental data. With respect to soot prediction, the kinetic scheme containing benzene elementary reactions tends to result in a better prediction on soot concentrations in comparison to those contain no benzene elementary reactions. Among five kinetic mechanisms being studied, the Qin combustion scheme mechanism turned to yield the best prediction on both flame temperature and soot levels.

  10. Shock tube study of the fuel structure effects on the chemical kinetic mechanisms responsible for soot formation

    NASA Technical Reports Server (NTRS)

    Frenklach, M.

    1983-01-01

    Soot formation in toluene-, benzene-, and acetylene-oxygen-argon mixtures was investigated to study soot formation in a combustion environment. High concentrations of oxygen completely suppress soot formation. The addition of oxygen at relatively low concentrations uniformly suppresses soot formation at high pressures, while at relatively lower pressures it suppresses soot formation at higher temperatures while promoting soot production at lower temperatures. The observed behavior indicates that oxidation reactions compete with ring fragmentation. The main conclusion to be drawn from the results is that the soot formation mechanism is probably the same for the pyrolysis and oxidation of hydrocarbons. That is, the addition of oxygen does not alter the soot route but rather promotes or inhibits this route by means of competitive reactions. An approach to empirical modeling of soot formation during pyrolysis of aromatic hydrocarbons is also presented.

  11. Interdigitated Pt-GaN Schottky interfaces for high-temperature soot-particulate sensing

    NASA Astrophysics Data System (ADS)

    So, Hongyun; Hou, Minmin; Jain, Sambhav R.; Lim, Jongwoo; Senesky, Debbie G.

    2016-04-01

    A microscale soot-particulate sensor using interdigitated platinum-gallium nitride (Pt-GaN) Schottky interfaces was developed to monitor fine soot particles within high-temperature environments (e.g., combustion exhausts and flues). Upon exposure to soot particles (30 to 50 nm in diameter) from an experimental chimney, an increased current (∼43.6%) is observed through the back-to-back Schottky contact to n-type GaN. This is attributed to a reduction in the effective Schottky barrier height (SBH) of ∼10 meV due to the electric field from the charged soot particles in the depletion region and exposed GaN surface. Furthermore, the microfabricated sensor was shown to recover sensitivity and regenerate the sensing response (∼11 meV SBH reduction) after exposure to temperature as high as 550 °C. This study supports the feasibility of a simple and reliable soot sensor to meet the increasing market demand for particulate matter sensing in harsh environments.

  12. Comparative Soot Diagnostics: 1 Year Report

    NASA Technical Reports Server (NTRS)

    Urban, David L.; Griffin, DeVon W.; Gard, Melissa Y.

    1998-01-01

    The motivation for the Comparative Soot Diagnostics (CSD) experiment lies in the broad practical importance of understanding combustion generated particulate. Depending upon the circumstances, particulate matter can affect the durability and performance of combustion equipment, can be a pollutant, can be used to detect fires and, in the form of soot, can be the dominant source of radiant energy from flames. Bright sooty fires are desirable for efficient energy extraction in furnaces and power equipment. In contrast, soot-enhanced radiation is undesirable in many propulsion systems (e.g. jet engines). The non-buoyant structure of most flames of practical interest (turbulent) makes understanding of soot processes in low gravity flames important to our ability to predict fire behavior on earth. These studies also have direct applications to fire safety in human-crew spacecraft, since smoke is the indicator used for automated detection in current spacecraft. In addition, recent tests conducted on MIR showed that a candle in a truly quiescent spacecraft environment can burn for tens of minutes. Consequently, this test and many earlier tests have demonstrated that fires in spacecraft can be considered a credible risk. In anticipation of this risk, NASA has included fire detectors on Skylab, smoke detectors on the Space Shuttle (STS), and smoke detectors in the design for the International Space Station (ISS). In the CSD experiment, these smoke detectors were tested using, quasi-steady, low-gravity, particulate generating materials. Samples of the particulate were also obtained from these low-gravity sources. This experiment provides the first such measurements aimed toward understanding of soot processes here on earth and for the testing and design of advanced spacecraft smoke detection systems. This paper describes the operation and preliminary results of the CSD experiment which was was conducted in the Middeck Glovebox Facility (MGBX) on USMP-3. The objectives of CSD

  13. Soot Oxidation in Laminar Hydrocarbon/Air Diffusion Flames at Atmospheric Pressure. Appendix D

    NASA Technical Reports Server (NTRS)

    Xu, F.; El-Leathy, A. M.; Faeth, G. M.

    2000-01-01

    Soot oxidation was studied experimentally in laminar hydrocarbon/air diffusion flames at atmospheric pressure. Measurements were carried out along the axes of round jets burning in coflowing air considering acetylene, ethylene, proplyene and propane as fuels. Measurements were limited to the initial stages of soot oxidation (carbon consumption less than 70%) where soot oxidation mainly occurs at the surface of primary soot particles. The following properties were measured as a function of distance above the burner exit: soot concentrations by deconvoluted laser extinction, soot temperatures by deconvoluted multiline emission, soot structure by thermophoretic sampling and analysis using Transmission Electron Microscopy (TEM), concentrations of stable major gas species (N2, H2O, H2, 02, CO, CO2, CH4, C2H2, C2H4, C2H6, C3H6, and C3H8) by sampling and gas chromatography, concentrations of some radical species (H, OH, O) by the deconvoluted Li/LiOH atomic absorption technique and flow velocities by laser velocimetry. It was found that soot surface oxidation rates are not particularly affected by fuel type for laminar diffusion flames and are described reasonably well by the OH surface oxidation mechanism with a collision efficiency of 0.10, (standard deviation of 0.07) with no significant effect of fuel type in this behavior; these findings are in good agreement with the classical laminar premixed flame measurements of Neoh et al. Finally, direct rates of surface oxidation by O2 were small compared to OH oxidation for present conditions, based on estimated O2 oxidation rates due to Nagle and Strickland-Constable, because soot oxidation was completed near the flame sheet where O2 concentrations were less than 1.2% by volume.

  14. Particle emissions from diesel passenger cars equipped with a particle trap in comparison to other technologies.

    PubMed

    Mohr, Martin; Forss, Anna-Maria; Lehmann, Urs

    2006-04-01

    Tail pipe particle emissions of passenger cars, with different engine and aftertreatment technologies, were determined with special focus on diesel engines equipped with a particle filter. The particle number measurements were performed, during transient tests, using a condensation particle counter. The measurement procedure complied with the draft Swiss ordinance, which is based on the findings of the UN/ECE particulate measurement program. In addition, particle mass emissions were measured by the legislated and a modified filter method. The results demonstrate the high efficiency of diesel particle filters (DPFs) in curtailing nonvolatile particle emissions over the entire size range. Higher emissions were observed during short periods of DPF regeneration and immediately afterward, when a soot cake has not yet formed on the filter surface. The gasoline vehicles exhibited higher emissions than the DPF equipped diesel vehicles but with a large variation depending on the technology and driving conditions. Although particle measurements were carried out during DPF regeneration, it was impossible to quantify their contribution to the overall emissions, due to the wide variation in intensity and frequency of regeneration. The numbers counting method demonstrated its clear superiority in sensitivity to the mass measurement. The results strongly suggest the application of the particle number counting to quantify future low tailpipe emissions.

  15. Suppression of Soot Formation and Shapes of Laminar Jet Diffusion Flames

    NASA Technical Reports Server (NTRS)

    Xu, F.; Dai, Z.; Faeth, G. M.

    2001-01-01

    Laminar nonpremixed (diffusion) flames are of interest because they provide model flame systems that are far more tractable for analysis and experiments than practical turbulent flames. In addition, many properties of laminar diffusion flames are directly relevant to turbulent diffusion flames using laminar flamelet concepts. Finally, laminar diffusion flame shapes have been of interest since the classical study of Burke and Schumann because they involve a simple nonintrusive measurement that is convenient for evaluating flame shape predictions. Motivated by these observations, the shapes of round hydrocarbon-fueled laminar jet diffusion flames were considered, emphasizing conditions where effects of buoyancy are small because most practical flames are not buoyant. Earlier studies of shapes of hydrocarbon-fueled nonbuoyant laminar jet diffusion flames considered combustion in still air and have shown that flames at the laminar smoke point are roughly twice as long as corresponding soot-free (blue) flames and have developed simple ways to estimate their shapes. Corresponding studies of hydrocarbon-fueled weakly-buoyant laminar jet diffusion flames in coflowing air have also been reported. These studies were limited to soot-containing flames at laminar smoke point conditions and also developed simple ways to estimate their shapes but the behavior of corresponding soot-free flames has not been addressed. This is unfortunate because ways of selecting flame flow properties to reduce soot concentrations are of great interest; in addition, soot-free flames are fundamentally important because they are much more computationally tractable than corresponding soot-containing flames. Thus, the objectives of the present investigation were to observe the shapes of weakly-buoyant laminar jet diffusion flames at both soot-free and smoke point conditions and to use the results to evaluate simplified flame shape models. The present discussion is brief.

  16. Measuring and predicting sooting tendencies of oxygenates, alkanes, alkenes, cycloalkanes, and aromatics on a unified scale

    DOE PAGES

    Das, Dhrubajyoti D.; St. John, Peter C.; McEnally, Charles S.; ...

    2017-12-27

    Databases of sooting indices, based on measuring some aspect of sooting behavior in a standardized combustion environment, are useful in providing information on the comparative sooting tendencies of different fuels or pure compounds. However, newer biofuels have varied chemical structures including both aromatic and oxygenated functional groups, which expands the chemical space of relevant compounds. In this work, we propose a unified sooting tendency database for pure compounds, including both regular and oxygenated hydrocarbons, which is based on combining two disparate databases of yield-based sooting tendency measurements in the literature. Unification of the different databases was made possible by leveragingmore » the greater dynamic range of the color ratio pyrometry soot diagnostic. This unified database contains a substantial number of pure compounds (≥ 400 total) from multiple categories of hydrocarbons important in modern fuels and establishes the sooting tendencies of aromatic and oxygenated hydrocarbons on the same numeric scale for the first time. Then, using this unified sooting tendency database, we have developed a predictive model for sooting behavior applicable to a broad range of hydrocarbons and oxygenated hydrocarbons. The model decomposes each compound into single-carbon fragments and assigns a sooting tendency contribution to each fragment based on regression against the unified database. The model’s predictive accuracy (as demonstrated by leave-one-out cross-validation) is comparable to a previously developed, more detailed predictive model. The fitted model provides insight into the effects of chemical structure on soot formation, and cases where its predictions fail reveal the presence of more complicated kinetic sooting mechanisms. Our work will therefore enable the rational design of low-sooting fuel blends from a wide range of feedstocks and chemical functionalities.« less

  17. Measuring and predicting sooting tendencies of oxygenates, alkanes, alkenes, cycloalkanes, and aromatics on a unified scale

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Das, Dhrubajyoti D.; St. John, Peter C.; McEnally, Charles S.

    Databases of sooting indices, based on measuring some aspect of sooting behavior in a standardized combustion environment, are useful in providing information on the comparative sooting tendencies of different fuels or pure compounds. However, newer biofuels have varied chemical structures including both aromatic and oxygenated functional groups, which expands the chemical space of relevant compounds. In this work, we propose a unified sooting tendency database for pure compounds, including both regular and oxygenated hydrocarbons, which is based on combining two disparate databases of yield-based sooting tendency measurements in the literature. Unification of the different databases was made possible by leveragingmore » the greater dynamic range of the color ratio pyrometry soot diagnostic. This unified database contains a substantial number of pure compounds (≥ 400 total) from multiple categories of hydrocarbons important in modern fuels and establishes the sooting tendencies of aromatic and oxygenated hydrocarbons on the same numeric scale for the first time. Then, using this unified sooting tendency database, we have developed a predictive model for sooting behavior applicable to a broad range of hydrocarbons and oxygenated hydrocarbons. The model decomposes each compound into single-carbon fragments and assigns a sooting tendency contribution to each fragment based on regression against the unified database. The model’s predictive accuracy (as demonstrated by leave-one-out cross-validation) is comparable to a previously developed, more detailed predictive model. The fitted model provides insight into the effects of chemical structure on soot formation, and cases where its predictions fail reveal the presence of more complicated kinetic sooting mechanisms. Our work will therefore enable the rational design of low-sooting fuel blends from a wide range of feedstocks and chemical functionalities.« less

  18. Neutron diffraction study of water freezing on aircraft engine combustor soot.

    PubMed

    Tishkova, V; Demirdjian, B; Ferry, D; Johnson, M

    2011-12-14

    The study of the formation of condensation trails and cirrus clouds on aircraft emitted soot particles is important because of its possible effects on climate. In the present work we studied the freezing of water on aircraft engine combustor (AEC) soot particles under conditions of pressure and temperature similar to the upper troposphere. The microstructure of the AEC soot was found to be heterogeneous containing both primary particles of soot and metallic impurities (Fe, Cu, and Al). We also observed various surface functional groups such as oxygen-containing groups, including sulfate ions, that can act as active sites for water adsorption. Here we studied the formation of ice on the AEC soot particles by using neutron diffraction. We found that for low amount of adsorbed water, cooling even up to 215 K did not lead to the formation of hexagonal ice. Whereas, larger amount of adsorbed water led to the coexistence of liquid water (or amorphous ice) and hexagonal ice (I(h)); 60% of the adsorbed water was in the form of ice I(h) at 255 K. Annealing of the system led to the improvement of the crystal quality of hexagonal ice crystals as demonstrated from neutron diffraction.

  19. Soot Volume Fraction Maps for Normal and Reduced Gravity Laminar Acetylene Jet Diffusion Flames

    NASA Technical Reports Server (NTRS)

    Greenberg, Paul S.; Ku, Jerry C.

    1997-01-01

    The study of soot particulate distribution inside gas jet diffusion flames is important to the understanding of fundamental soot particle and thermal radiative transport processes, as well as providing findings relevant to spacecraft fire safety, soot emissions, and radiant heat loads for combustors used in air-breathing propulsion systems. Compared to those under normal gravity (1-g) conditions, the elimination of buoyancy-induced flows is expected to significantly change the flow field in microgravity (O g) flames, resulting in taller and wider flames with longer particle residence times. Work by Bahadori and Edelman demonstrate many previously unreported qualitative and semi-quantitative results, including flame shape and radiation, for sooting laminar zas jet diffusion flames. Work by Ku et al. report soot aggregate size and morphology analyses and data and model predictions of soot volume fraction maps for various gas jet diffusion flames. In this study, we present the first 1-g and 0-g comparisons of soot volume fraction maps for laminar acetylene and nitrogen-diluted acetylene jet diffusion flames. Volume fraction is one of the most useful properties in the study of sooting diffusion flames. The amount of radiation heat transfer depends directly on the volume fraction and this parameter can be measured from line-of-sight extinction measurements. Although most Soot aggregates are submicron in size, the primary particles (20 to 50 nm in diameter) are in the Rayleigh limit, so the extinction absorption) cross section of aggregates can be accurately approximated by the Rayleigh solution as a function of incident wavelength, particles' complex refractive index, and particles' volume fraction.

  20. Effects of Structure and Hydrodynamics on the Sooting Behavior of Spherical Microgravity Diffusion Flames

    NASA Technical Reports Server (NTRS)

    Sunderland, P. B.; Axelbaum, R. L.; Urban, D. L.

    1999-01-01

    Recent experimental, numerical and analytical work has shown that the stoichiometric mixture fraction (Z(sub st)) can have a profound effect on soot formation in diffusion flames. These findings were obtained at constant flame temperature (T(sub ad)), employing the approach described in Du and Axelbaum (1995, 1996). For example, a fuel mixture containing 1 mole of ethylene and 11.28 moles of nitrogen burning in pure oxygen ((Z(sub st)) = 0.78) has the same adiabatic flame temperature (2370 K) as that of pure ethylene burning in air ((Z(sub st)) = 0.064). An important finding of these works was that at sufficiently high (Z(sub st)), flames remain blue as strain rate approaches zero in counterflow flames, or as flame height and residence time approach infinity in coflowing flames. Lin and Faeth (1996a) coined the term permanently blue to describe such flames. Two theories have been proposed to explain the appearance of permanently-blue flames at high (Z(sub st)). They are based on (1) hydrodynamics and (2) flame structure. Previous experimental studies in normal gravity are not definitive as to which, if either, mechanism is dominant because both hydrodynamics and structure suppress soot formation at high (Z(sub st)) in coflowing and counterflowing diffusion flames. In counterflow flames with (Z(sub st)) < 0.5 streamlines at the flame sheet are directed toward the fuel. Newly formed soot is convected into richer regions, favoring soot growth over oxidation. For (Z(sub st)) > 0.5, convection at the flame is toward the oxidizer, thus enhancing soot oxidization. Thus, in counterflow flames, hydrodynamics causes soot to be convected towards the oxidizer at high (Z(sub st)) which suppresses soot formation. Axelbaum and co-workers maintain that while the direction of convection can impact soot growth and oxidation, these processes alone cannot cause permanently-blue flames. Soot growth and oxidation are dependent on the existence of soot particles and the presence of soot

  1. Carbon stardust: From soot to diamonds

    NASA Technical Reports Server (NTRS)

    Tielens, Alexander G. G. M.

    1990-01-01

    The formation of carbon dust in the outflow from stars and the subsequent evolution of this so called stardust in the interstellar medium is reviewed. The chemical and physical processes that play a role in carbon stardust formation are very similar to those occurring in sooting flames. Based upon extensive laboratory studies of the latter, the structure and physical and chemical properties of carbon soot are reviewed and possible chemical pathways towards carbon stardust are discussed. Grain-grain collisions behind strong interstellar shocks provide the high pressures required to transform graphite and amorphous carbon grains into diamond. This process is examined and the properties of shock-synthesized diamonds are reviewed. Finally, the interrelationship between carbon stardust and carbonaceous meteorites is briefly discussed.

  2. Flame structure of wall-impinging diesel fuel sprays injected by group-hole nozzles

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gao, Jian; Moon, Seoksu; Nishida, Keiya

    This paper describes an investigation of the flame structure of wall-impinging diesel sprays injected by group-hole nozzles in a constant-volume combustion vessel at experimental conditions typical of a diesel engine. The particular emphasis was on the effect of the included angle between two orifices (0-15 deg. in current study) on the flame structure and combustion characteristics under various simulated engine load conditions. The laser absorption scattering (LAS) technique was applied to analyze the spray and mixture properties. Direct flame imaging and OH chemiluminescence imaging were utilized to quantify the ignition delay, flame geometrical parameters, and OH chemiluminescence intensity. The imagesmore » show that the asymmetric flame structure emerges in wall-impinging group-hole nozzle sprays as larger included angle and higher engine load conditions are applied, which is consistent with the spray shape observed by LAS. Compared to the base nozzle, group-hole nozzles with large included angles yield higher overall OH chemiluminescence intensity, wider flame area, and greater proportion of high OH intensity, implying the better fuel/air mixing and improved combustion characteristics. The advantages of group-hole nozzle are more pronounced under high load conditions. Based on the results, the feasibility of group-hole nozzle for practical direct injection diesel engines is also discussed. It is concluded that the asymmetric flame structure of a group-hole nozzle spray is favorable to reduce soot formation over wide engine loads. However, the hole configuration of the group-hole nozzle should be carefully considered so as to achieve proper air utilization in the combustion chamber. Stoichiometric diesel combustion is another promising application of group-hole nozzle. (author)« less

  3. Effects of Gravity on Soot Formation in a Coflow Laminar Methane/Air Diffusion Flame

    NASA Astrophysics Data System (ADS)

    Kong, Wenjun; Liu, Fengshan

    2010-04-01

    Simulations of a laminar coflow methane/air diffusion flame at atmospheric pressure are conducted to gain better understanding of the effects of gravity on soot formation by using detailed gas-phase chemistry, complex thermal and transport properties coupled with a semiempirical two-equation soot model and a nongray radiation model. Soot oxidation by O2, OH and O was considered. Thermal radiation was calculated using the discrete ordinate method coupled with a statistical narrow-band correlated-K model. The spectral absorption coefficient of soot was obtained by Rayleigh's theory for small particles. The results show that the peak temperature decreases with the decrease of the gravity level. The peak soot volume fraction in microgravity is about twice of that in normal gravity under the present conditions. The numerical results agree very well with available experimental results. The predicted results also show that gravity affects the location and intensity for soot nucleation and surface growth.

  4. Chromatic variation of soot soiling: a possible marker for gunshot wounds in burnt bone.

    PubMed

    Amadasi, Alberto; Merli, Daniele; Brandone, Alberto; Cattaneo, Cristina

    2014-01-01

    Soot soiling is a crucial forensic parameter around gunshot lesions. Carbonization, however, can severely alter human tissues and mimic such clues. This study aims at evaluating the survival of soot soiling even after carbonization in bone. A total of 36 bovine ribs (half fleshed and half defleshed) were shot with two types of bullet (both 9-mm; full metal-jacketed and unjacketed) with a near-contact range. With unjacketed bullets, the shot left in every case a clear, black, and roughly round soot stain around the entrance wound, whereas full metal-jacketed bullets left no signs of soot. Every specimen then underwent calcination in an oven at 800°C. The analysis of the charred samples clearly showed the survival of the soot soiling in both fleshed and bony samples, with a clear correspondence with the former position, but with a different color (yellow). Thus, soot soiling may survive, although with a different color, even after charring. © 2013 American Academy of Forensic Sciences.

  5. Experimental Investigation of Nascent Soot Physical Properties and The Influence on Particle Morphology and Growth

    NASA Astrophysics Data System (ADS)

    Lieb, Sydnie Marie

    Soot released to the atmosphere is a dangerous pollutant for human health and the environment. Understanding the physical properties and surface properties of these particles is important to properly explaining the growth of soot particles in flames as well as their interactions with other particles and gases in the environment. Particles below 15 nm in diameter, nascent soot particles, dominate the early growth stages of soot formation; previously these particles were characterized as hard graphitic spheres. New evidence derived from the current dissertation work, to a large extent, challenges this prior characterization. This dissertation study begins by revisiting the use of atomic force microscope (AFM) as a tool to investigate the structural properties of nascent soot. The impact of tip artifacts, which are known to complicate measurements of features below 10 nm in diameter, are carefully considered so as to provide a concise interpretation of the morphology of nascent soot as seen by AFM. The results of the AFM morphology collaborate with earlier photo- and thermal-fragmentation particle mass spectrometry and Fourier transform infrared spectroscopy that nascent soot is not a graphitized carbon material and that they are not spherical. Furthermore, phase mode imaging is introduced as a method to investigate the physical properties of nascent soot particles in a greater detail and finer resolution. The helium ion microscope (HIM) has been identified as a useful technique for the imaging of nascent soot. Using this imaging method nascent soot particles were imaged with a high resolution that had not been obtained by prior techniques. The increased contrast provides a closer look at the nascent soot particles and further suggested that these particles are not as structurally homogeneous as previously thought. Geometric shape analysis was performed to characterize the particles in terms of sphericity, circularity, and fractal dimension. The geometric analysis

  6. Influence of thermal radiation on soot production in Laminar axisymmetric diffusion flames

    NASA Astrophysics Data System (ADS)

    Demarco, R.; Nmira, F.; Consalvi, J. L.

    2013-05-01

    The aim of this paper is to study the effect of radiative heat transfer on soot production in laminar axisymmetric diffusion flames. Twenty-four C1-C3 hydrocarbon-air flames, consisting of normal (NDF) and inverse (IDF) diffusion flames at both normal gravity (1 g) and microgravity (0 g), and covering a wide range of conditions affecting radiative heat transfer, were simulated. The numerical model is based on the Steady Laminar Flamelet (SLF) model, a semi-empirical two-equation acetylene/benzene based soot model and the Statistical Narrow Band Correlated K (SNBCK) model coupled to the Finite Volume Method (FVM) to compute thermal radiation. Predictions relative to velocity, temperature, soot volume fraction and radiative losses are on the whole in good agreement with the available experimental data. Model results show that, for all the flames considered, thermal radiation is a crucial process with a view to providing accurate predictions for temperatures and soot concentrations. It becomes increasingly significant from IDFs to NDFs and its influence is much greater as gravity is reduced. The radiative contribution of gas prevails in the weakly-sooting IDFs and in the methane and ethane NDFs, whereas soot radiation dominates in the other flames. However, both contributions are significant in all cases, with the exception of the 1 g IDFs investigated where soot radiation can be ignored. The optically-thin approximation (OTA) was also tested and found to be applicable as long as the optical thickness, based on flame radius and Planck mean absorption coefficient, is less than 0.05. The OTA is reasonable for the IDFs and for most of the 1 g NDFs, but it fails to predict the radiative heat transfer for the 0 g NDFs. The accuracy of radiative-property models was then assessed in the latter cases. Simulations show that the gray approximation can be applied to soot but not to combustion gases. Both the non-gray and gray soot versions of the Full Spectrum Correlated k (FSCK

  7. Towards predictive simulations of soot formation: from surrogate to turbulence

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Blanquart, Guillaume

    The combustion of transportation fuels leads to the formation of several kinds of pollutants, among which are soot particles. These particles, also formed during coal combustion and in fires, are the source of several health problems and environmental issues. Unfortunately, our current understanding of the chemical and physical phenomena leading to the formation of soot particles remains incomplete, and as a result, the predictive capability of our numerical tools is lacking. The objective of the work was to reduce the gap in the present understanding and modeling of soot formation both in laminar and turbulent flames. The effort spanned severalmore » length scales from the molecular level to large scale turbulent transport.« less

  8. Soot Formation in Laminar Premixed Ethylene/Air Flames at Atmospheric Pressure. Appendix G

    NASA Technical Reports Server (NTRS)

    Xu, F.; Sunderland, P. B.; Faeth, G. M.; Urban, D. L. (Technical Monitor)

    2001-01-01

    Soot formation was studied within laminar premixed ethylene/air flames (C/O ratios of 0.78-0.98) stabilized on a flat-flame burner operating at atmospheric pressure. Measurements included soot volume fractions by both laser extinction and gravimetric methods, temperatures by multiline emission, soot structure by thermophoretic sampling and transmission electron microscopy, major gas species concentrations by sampling and gas chromatography, concentrations of condensable hydrocarbons by gravimetric sampling. and velocities by laser velocimetry. These data were used to find soot surface growth rates and primary soot particle nucleation rates along the axes of the flames. Present measurements of soot surface growth rates were correlated successfully by predictions based on typical hydrogen-abstraction/carbon-addition (HACA) mechanisms of Frenklach and co-workers and Colket and Hall. These results suavest that reduced soot surface growth rates with increasing residence time seen in the present and other similar flames were mainly caused by reduced rates of surface activation due to reduced H atom concentrations as temperatures decrease as a result of radiative heat losses. Primary soot particle nucleation rates exhibited variations with temperature and acetylene concentrations that were similar to recent observations for diffusion flames; however, nucleation rates in the premixed flames were significantly lower than in, the diffusion flames for reasons that still must be explained. Finally, predictions of yields of major gas species based on mechanisms from both Frenklach and co-workers and Leung and Lindstedt were in good agreement with present measurements and suggest that H atom concentrations (relevant to HACA mechanisms) approximate estimates based on local thermodynamic equilibrium in the present flames.

  9. Use of a Chamber to Comprehensively Characterise Emissions and Subsequent Processes from a Light-Duty Diesel Engine

    NASA Astrophysics Data System (ADS)

    Allan, J. D.; Alfarra, M. R. R.; Whitehead, J.; McFiggans, G.; Kong, S.; Harrison, R. M.; Alam, M. S.; Hamilton, J. F.; Pereira, K. L.; Holmes, R. E.

    2014-12-01

    Around 1 in 3 light duty vehicles in the UK use diesel engines, meaning that on-road emissions of particulates, NOx and VOCs and subsequent chemical processes are substantially different to countries where gasoline engines dominate. As part of the Natural Environment Research Council (NERC) Com-Part project, emissions from a diesel engine dynamometer rig representative of the EURO 4 standard were studied. The exhaust was passed to the Manchester aerosol chamber, which consists of an 18 m3 teflon bag and by injecting a sample of exhaust fumes into filtered and chemically scrubbed air, a controllable dilution can be performed and the sample held in situ for analysis by a suite of instruments. The system also allows the injection of other chemicals (e.g. ozone, additional VOCs) and the initiation of photochemistry using a bank of halogen bulbs and a filtered Xe arc lamp to simulate solar light. Because a large volume of dilute emissions can be held for a period of hours, this permits a wide range of instrumentation to be used and relatively slow processes studied. Furthermore, because the bag is collapsible, the entire particulate contents can be collected on a filter for offline analysis. Aerosol microphysical properties are studied using a Scanning Mobility Particle Sizer (SMPS) and Centrifugal Particle Mass Analyser (CPMA); aerosol composition using a Soot Particle Aerosol Mass Spectrometer (SP-AMS), Single Particle Soot Photometer (SP2), Sunset Laboratories OC EC analyser and offline gas- and high performance liquid chromatography (employing advanced mass spectrometry such as ion trap and fourier transform ion cyclotron resonance); VOCs using comprehensive 2D gas chromatography; aerosol optical properties using a Cavity Attenuated Phase Shift Single Scattering Albedo monitor (CAPS-PMSSA), 3 wavelength Photoacoustic Soot Spectrometer (PASS-3) and Multi Angle Absorption Photometer (MAAP); particle hygroscopcity using a Hygroscopicity Tandem Differential Mobility

  10. Numerical modelling of soot formation and oxidation in laminar coflow non-smoking and smoking ethylene diffusion flames

    NASA Astrophysics Data System (ADS)

    Liu, Fengshan; Guo, Hongsheng; Smallwood, Gregory J.; Gülder, Ömer L.

    2003-06-01

    A numerical study of soot formation and oxidation in axisymmetric laminar coflow non-smoking and smoking ethylene diffusion flames was conducted using detailed gas-phase chemistry and complex thermal and transport properties. A modified two-equation soot model was employed to describe soot nucleation, growth and oxidation. Interaction between the gas-phase chemistry and soot chemistry was taken into account. Radiation heat transfer by both soot and radiating gases was calculated using the discrete-ordinates method coupled with a statistical narrow-band correlated-k based band model, and was used to evaluate the simple optically thin approximation. The governing equations in fully elliptic form were solved. The current models in the literature describing soot oxidation by O2 and OH have to be modified in order to predict the smoking flame. The modified soot oxidation model has only moderate effects on the calculation of the non-smoking flame, but dramatically affects the soot oxidation near the flame tip in the smoking flame. Numerical results of temperature, soot volume fraction and primary soot particle size and number density were compared with experimental data in the literature. Relatively good agreement was found between the prediction and the experimental data. The optically thin approximation radiation model significantly underpredicts temperatures in the upper portion of both flames, seriously affecting the soot prediction.

  11. On the radiative properties of soot aggregates part 1: Necking and overlapping

    NASA Astrophysics Data System (ADS)

    Yon, J.; Bescond, A.; Liu, F.

    2015-09-01

    There is a strong interest in accurately modelling the radiative properties of soot aggregates (also known as black carbon particles) emitted from combustion systems and fires to gain improved understanding of the role of black carbon to global warming. This study conducted a systematic investigation of the effects of overlapping and necking between neighbouring primary particles on the radiative properties of soot aggregates using the discrete dipole approximation. The degrees of overlapping and necking are quantified by the overlapping and necking parameters. Realistic soot aggregates were generated numerically by constructing overlapping and necking to fractal aggregates formed by point-touch primary particles simulated using a diffusion-limited cluster aggregation algorithm. Radiative properties (differential scattering, absorption, total scattering, specific extinction, asymmetry factor and single scattering albedo) were calculated using the experimentally measured soot refractive index over the spectral range of 266-1064 nm for 9 combinations of the overlapping and necking parameters. Overlapping and necking affect significantly the absorption and scattering properties of soot aggregates, especially in the near UV spectrum due to the enhanced multiple scattering effects within an aggregate. By using correctly modified aggregate properties (fractal dimension, prefactor, primary particle radius, and the number of primary particle) and by accounting for the effects of multiple scattering, the simple Rayleigh-Debye-Gans theory for fractal aggregates can reproduce reasonably accurate radiative properties of realistic soot aggregates.

  12. A multi-probe thermophoretic soot sampling system for high-pressure diffusion flames

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Vargas, Alex M.; Gülder, Ömer L.

    Optical diagnostics and physical probing of the soot processes in high pressure combustion pose challenges that are not faced in atmospheric flames. One of the preferred methods of studying soot in atmospheric flames is in situ thermophoretic sampling followed by transmission electron microscopy imaging and analysis for soot sizing and morphology. The application of this method of sampling to high pressures has been held back by various operational and mechanical problems. In this work, we describe a rotating disk multi-probe thermophoretic soot sampling system, driven by a microstepping stepper motor, fitted into a high-pressure chamber capable of producing sooting laminarmore » diffusion flames up to 100 atm. Innovative aspects of the sampling system design include an easy and precise control of the sampling time down to 2.6 ms, avoidance of the drawbacks of the pneumatic drivers used in conventional thermophoretic sampling systems, and the capability to collect ten consecutive samples in a single experimental run. Proof of principle experiments were performed using this system in a laminar diffusion flame of methane, and primary soot diameter distributions at various pressures up to 10 atm were determined. High-speed images of the flame during thermophoretic sampling were recorded to assess the influence of probe intrusion on the flow field of the flame.« less

  13. Shapes of soot aerosol particles and implications for their effects on climate

    NASA Astrophysics Data System (ADS)

    Adachi, Kouji; Chung, Serena H.; Buseck, Peter R.

    2010-08-01

    Soot aerosol particles (also called light-absorbing, black, or elemental carbon) are major contributors to global warming through their absorption of solar radiation. When embedded in organic matter or sulfate, as is common in polluted areas such as over Mexico City (MC) and other megacities, their optical properties are affected by their shapes and positions within their host particles. However, large uncertainties remain regarding those variables and how they affect warming by soot. Using electron tomography with a transmission electron microscope, three-dimensional (3-D) images of individual soot particles embedded within host particles collected from MC and its surroundings were obtained. From those 3-D images, we calculated the optical properties using a discrete dipole approximation. Many soot particles have open, chainlike shapes even after being surrounded by organic matter and are located in off-center positions within their host materials. Such embedded soot absorbs sunlight less efficiently than if compact and located near the center of its host particle. In the case of our MC samples, their contribution to direct radiative forcing is ˜20% less than if they had a simple core-shell shape, which is the shape assumed in many climate models. This study shows that the shapes and positions of soot within its host particles have an important effect on particle optical properties and should be recognized as potentially important variables when evaluating global climate change.

  14. Optical properties of soot particles: measurement - model comparison

    NASA Astrophysics Data System (ADS)

    Forestieri, S.; Lambe, A. T.; Lack, D.; Massoli, P.; Cross, E. S.; Dubey, M.; Mazzoleni, C.; Olfert, J.; Freedman, A.; Davidovits, P.; Onasch, T. B.; Cappa, C. D.

    2013-12-01

    Soot, a product of incomplete combustion, plays an important role in the earth's climate system through the absorption and scattering of solar radiation. In order to accurately model the direct radiative impact of black carbon (BC), the refractive index and shape dependent scattering and absorption characteristics must be known. At present, the assumed shape remains highly uncertain because BC particles are fractal-like, being agglomerates of smaller (20-40 nm) spherules, yet traditional optical models such as Mie theory typically assume a spherical particle morphology. To investigate the ability of various optical models to reproduce observed BC optical properties, we measured light absorption and extinction coefficients of methane and ethylene flame soot particles. Optical properties were measured by multiple instruments: absorption by a dual cavity ringdown photoacoustic spectrometer (CRD-PAS), absorption and scattering by a 3-wavelength photoacoustic/nephelometer spectrometer (PASS-3) and extinction and scattering by a cavity attenuated phase shift spectrometer (CAPS). Soot particle mass was quantified using a centrifugal particle mass analyzer (CPMA) and mobility size was measured with a scanning mobility particle sizer (SMPS). Measurements were made for nascent soot particles and for collapsed soot particles following coating with dioctyl sebacate or sulfuric acid and thermal denuding to remove the coating. Wavelength-dependent refractive indices for the sampled particles were derived by fitting the observed absorption and extinction cross-sections to spherical particle Mie theory and Rayleigh-Debye-Gans theory. The Rayleigh-Debye-Gans approximation assumes that the absorption properties of soot are dictated by the individual spherules and neglects interaction between them. In general, Mie theory reproduces the observed absorption and extinction cross-sections for particles with volume equivalent diameters (VED) < ~160 nm, but systematically predicts lower

  15. Simulations of sooting turbulent jet flames using a hybrid flamelet/stochastic Eulerian field method

    NASA Astrophysics Data System (ADS)

    Consalvi, Jean-Louis; Nmira, Fatiha; Burot, Daria

    2016-03-01

    The stochastic Eulerian field method is applied to simulate 12 turbulent C1-C3 hydrocarbon jet diffusion flames covering a wide range of Reynolds numbers and fuel sooting propensities. The joint scalar probability density function (PDF) is a function of the mixture fraction, enthalpy defect, scalar dissipation rate and representative soot properties. Soot production is modelled by a semi-empirical acetylene/benzene-based soot model. Spectral gas and soot radiation is modelled using a wide-band correlated-k model. Emission turbulent radiation interactions (TRIs) are taken into account by means of the PDF method, whereas absorption TRIs are modelled using the optically thin fluctuation approximation. Model predictions are found to be in reasonable agreement with experimental data in terms of flame structure, soot quantities and radiative loss. Mean soot volume fractions are predicted within a factor of two of the experiments whereas radiant fractions and peaks of wall radiative fluxes are within 20%. The study also aims to assess approximate radiative models, namely the optically thin approximation (OTA) and grey medium approximation. These approximations affect significantly the radiative loss and should be avoided if accurate predictions of the radiative flux are desired. At atmospheric pressure, the relative errors that they produced on the peaks of temperature and soot volume fraction are within both experimental and model uncertainties. However, these discrepancies are found to increase with pressure, suggesting that spectral models describing properly the self-absorption should be considered at over-atmospheric pressure.

  16. Key role of organic carbon in the sunlight-enhanced atmospheric aging of soot by O2

    PubMed Central

    Han, Chong; Liu, Yongchun; Ma, Jinzhu; He, Hong

    2012-01-01

    Soot particles are ubiquitous in the atmosphere and have important climatic and health effects. The aging processes of soot during long-range transport result in variability in its morphology, microstructure, and hygroscopic and optical properties, subsequently leading to the modification of soot’s climatic and health effects. In the present study the aging process of soot by molecular O2 under simulated sunlight irradiation is investigated. Organic carbon components on the surface of soot are found to play a key role in soot aging and are transformed into oxygen-containing organic species including quinones, ketones, aldehydes, lactones, and anhydrides. These oxygen-containing species may become adsorption centers of water and thus enhance the cloud condensation nuclei and ice nuclei activities of soot. Under irradiation of 25 mW·cm−2, the apparent rate constants (k1,obs) for loss or formation of species on soot aged by 20% O2 were larger by factors of 1.5–3.5 than those on soot aged by 100 ppb O3. Considering the abundance of O2 in the troposphere and its higher photoreactivity rate, the photochemical oxidation by O2 under sunlight irradiation should be a very important aging process for soot. PMID:23236134

  17. Development and validation of a new soot formation model for gas turbine combustor simulations

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Di Domenico, Massimiliano; Gerlinger, Peter; Aigner, Manfred

    2010-02-15

    In this paper a new soot formation model for gas turbine combustor simulations is presented. A sectional approach for the description of Polycyclic Aromatic Hydrocarbons (PAHs) and a two-equation model for soot particle dynamics are introduced. By including the PAH chemistry the formulation becomes more general in that the soot formation is neither directly linked to the fuel nor to C{sub 2}-like species, as it is the case in simpler soot models currently available for CFD applications. At the same time, the sectional approach for the PAHs keeps the required computational resources low if compared to models based on amore » detailed description of the PAH kinetics. These features of the new model allow an accurate yet affordable calculation of soot in complex gas turbine combustion chambers. A careful model validation will be presented for diffusion and partially premixed flames. Fuels ranging from methane to kerosene are investigated. Thus, flames with different sooting characteristics are covered. An excellent agreement with experimental data is achieved for all configurations investigated. A fundamental feature of the new model is that with a single set of constants it is able to accurately describe the soot dynamics of different fuels at different operating conditions. (author)« less

  18. Airborne concentrations of PM(2.5) and diesel exhaust particles on Harlem sidewalks: a community-based pilot study.

    PubMed

    Kinney, P L; Aggarwal, M; Northridge, M E; Janssen, N A; Shepard, P

    2000-03-01

    Residents of the dense urban core neighborhoods of New York City (NYC) have expressed increasing concern about the potential human health impacts of diesel vehicle emissions. We measured concentrations of particulate matter [less than/equal to] 2.5 micro in aerodynamic diameter (PM(2.5)) and diesel exhaust particles (DEP) on sidewalks in Harlem, NYC, and tested whether spatial variations in concentrations were related to local diesel traffic density. Eight-hour (1000-1800 hr) air samples for PM(2.5 )and elemental carbon (EC) were collected for 5 days in July 1996 on sidewalks adjacent to four geographically distinct Harlem intersections. Samples were taken using portable monitors worn by study staff. Simultaneous traffic counts for diesel trucks, buses, cars, and pedestrians were carried out at each intersection on [Greater/equal to] 2 of the 5 sampling days. Eight-hour diesel vehicle counts ranged from 61 to 2,467 across the four sites. Mean concentrations of PM(2.5) exhibited only modest site-to-site variation (37-47 microg/m(3)), reflecting the importance of broader regional sources of PM(2.5). In contrast, EC concentrations varied 4-fold across sites (from 1.5 to 6 microg/m(3)), and were associated with bus and truck counts on adjacent streets and, at one site, with the presence of a bus depot. A high correlation (r = 0.95) was observed between EC concentrations measured analytically and a blackness measurement based on PM(2.5) filter reflectance, suggesting the utility of the latter as a surrogate measure of DEP in future community-based studies. These results show that local diesel sources in Harlem create spatial variations in sidewalk concentrations of DEP. The study also demonstrates the feasibility of a new paradigm for community-based research involving full and active partnership between academic scientists and community-based organizations.

  19. Cloud condensation nuclei and ice nucleation activity of hydrophobic and hydrophilic soot particles.

    PubMed

    Koehler, Kirsten A; DeMott, Paul J; Kreidenweis, Sonia M; Popovicheva, Olga B; Petters, Markus D; Carrico, Christian M; Kireeva, Elena D; Khokhlova, Tatiana D; Shonija, Natalia K

    2009-09-28

    Cloud condensation nuclei (CCN) activity and ice nucleation behavior (for temperaturessoot aerosols relevant for atmospheric studies were investigated. Soots were chosen to represent a range of physico-chemical properties, from hydrophobic through a range of hydrophilicity, to hygroscopic. These characteristics were achieved through generation by three different combustion sources; three soots from natural gas pyrolysis (original: TS; graphitized: GTS; and oxidized: TOS), soot from a diffusion flame in an oil lamp burning aviation kerosene (TC1), and soot from a turbulent diffusion flame in an aircraft engine combustor (AEC). All of the samples exhibited some heterogeneity in our experiments, which showed evidence of two or more particle sub-types even within a narrow size cut. The heterogeneity could have resulted from both chemical and sizing differences, the latter attributable in part to particle non-sphericity. Neither GTS nor TS, hydrophobic particles distinguished only by the lower porosity and polarity of the GTS surface, showed CCN activity at or below water supersaturations required for wettable, insoluble particles (the Kelvin limit). TC1 soot particles, despite classification as hydrophilic, did not show CCN activity at or below the Kelvin limit. We attribute this result to the microporosity of this soot. In contrast, oxidized, non-porous, and hydrophilic TOS particles exhibited CCN activation at very near the Kelvin limit, with a small percentage of these particles CCN-active even at lower supersaturations. Due to containing a range of surface coverage of organic and inorganic hydrophilic and hygroscopic compounds, up to approximately 35% of hygroscopic AEC particles were active as CCN, with a small percentage of these particles CCN-active at lower supersaturations. In ice nucleation experiments below -40 degrees C, AEC particles nucleated ice near the expected condition for homogeneous freezing of water from aqueous solutions. In

  20. Voluntary program to reduce soot

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2013-01-01

    The U.S. Environmental Protection Agency (EPA) announced on 17 January that it has formulated a voluntary clean air program, Particulate Matter (PM) Advance, to help communities develop strategies to reduce fine-particle emissions, often called soot or particulate matter, that can be harmful to human health.

  1. The competition between mineral dust and soot ice nuclei in mixed-phase clouds (Invited)

    NASA Astrophysics Data System (ADS)

    Murray, B. J.; Atkinson, J.; Umo, N.; Browse, J.; Woodhouse, M. T.; Whale, T.; Baustian, K. J.; Carslaw, K. S.; Dobbie, S.; O'Sullivan, D.; Malkin, T. L.

    2013-12-01

    The amount of ice present in mixed-phase clouds, which contain both supercooled liquid water droplets and ice particles, affects cloud extent, lifetime, particle size and radiative properties. The freezing of cloud droplets can be catalysed by the presence of aerosol particles known as ice nuclei. In this talk our recent laboratory and global aerosol modelling work on mineral dust and soot ice nuclei will be presented. We have performed immersion mode experiments to quantify ice nucleation by the individual minerals which make up desert mineral dusts and have shown that the feldspar component, rather than the clay component, is most important for ice nucleation (Atkinson et al. 2013). Experiments with well-characterised soot generated with eugenol, an intermediate in biomass burning, and n-decane show soot has a significant ice nucleation activity in mixed-phase cloud conditions. Our results for soot are in good agreement with previous results for acetylene soot (DeMott, 1990), but extend the efficiency to much higher temperatures. We then use a global aerosol model (GLOMAP) to map the distribution of soot and feldspar particles on a global basis. We show that below about -15oC that dust and soot together can explain most observed ice nuclei in the Earth's atmosphere, while at warmer temperatures other ice nuclei types are needed. We show that in some regions soot is the most important ice nuclei (below -15oC), while in others feldspar dust dominates. Our results suggest that there is a strong anthropogenic contribution to the ice nuclei population, since a large proportion of soot aerosol in the atmosphere results from human activities. Atkinson, J. D., Murray, B. J., Woodhouse, M. T., Carslaw, K. S., Whale, T. F., Baustian, K. J., Dobbie, S., O'Sullivan, D., and Malkin, T. L.: The importance of feldspar for ice nucleation by mineral dust in mixed-phase clouds, Nature, 10.1038/nature12278, (2013). Demott, P. J. 1990. An Exploratory-Study of Ice Nucleation by Soot

  2. Megacity pollution by modern Diesel cars: New insights into the nature and formation of volatile nano-particles with high lung intrusion efficiency

    NASA Astrophysics Data System (ADS)

    Arnold, F.; Reichl, U.; Muschik, Ch.; Roiger, A.; Schlager, H.; Pirjola, L.; Rönkkö, T.; Keskinen, J.; Rothe, D.; Lähde, T.

    2009-04-01

    Aerosol particles generated by Diesel vehicles represent mayor health affecting air pollutants in cities and near motor ways. To mitigate the Diesel particle pollution problem, Diesel vehicles become increasingly fitted or retro-fitted with modern exhaust after treatment systems (ATS), which remove most engine-generated primary particles, particularly soot. Unfortunately however, ATS have undesired side effects including also the formation of low vapour pressure gases, which may undergo nucleation and condensation leading to volatile nucleation particles (NUP). NUP are substantially smaller (diameters: 5-15 nm) than soot particles (diameters: 40-100 nm), and therefore may be termed real nano-particles. NUP can intrude with maximum efficiency the lowest, least protected, and most vulnerable compartment of the human lung. However, the chemical nature and mechanism of formation of NUP are only poorly explored. Using a novel mass spectrometric method, we have made the first on line and off line measurements of low vapour pressure NUP precursor gases in the exhaust of a modern heavy duty Diesel vehicle engine, operated with and without ATS and combusting low and ultra-low sulphur fuels including also bio fuel. In addition, we have made accompanying NUP measurements and NUP model simulations. The on line measurements involved a CIMS (Chemical Ionization Mass Spectrometry) method originally developed by MPIK. They took place directly in the Diesel exhaust and had a large sensitivity and a fast time response (1 s). The off line measurements involved adsorption of exhaust gases on stainless steel, followed by thermo desorption and detection of desorbed exhaust molecules by CIMS. We find that modern Diesel ATS strongly increase the formation of hydroxyl radicals, which induce conversion of fuel sulphur to the important NUP precursor gaseous sulphuric acid. We also find that appreciable amounts of di-carboxylic acids survive the passage of the ATS or are even formed by the

  3. Diesel exhaust, diesel fumes, and laryngeal cancer.

    PubMed

    Muscat, J E; Wynder, E L

    1995-03-01

    A hospital-based, case-control study of 235 male patients with laryngeal cancer and 205 male control patients was conducted to determine the effects of exposure to diesel engine exhaust and diesel fumes and the risk of laryngeal cancer. All patients were interviewed directly in the hospital with a standardized questionnaire that gathered information on smoking habits, alcohol consumption, employment history, and occupational exposures. Occupations that involve substantial exposure to diesel engine exhaust include mainly truck drivers, as well as mine workers, firefighters, and railroad workers. The odds ratio for laryngeal cancer associated with these occupations was 0.96 (95% confidence interval, 0.5 to 1.8). The odds ratio for self-reported exposure to diesel exhaust was 1.47 (95% confidence interval, 0.5 to 4.1). An elevated risk was found for self-reported exposure to diesel fumes (odds ratio, 6.4; 95% confidence interval, 1.8 to 22.6). No association was observed between jobs that entail exposure to diesel fumes, such as automobile mechanics, and the risk of laryngeal cancer. These results show that diesel engine exhaust is unrelated to laryngeal cancer risk. The different findings for self-reported diesel fumes and occupations that involve exposure to diesel fumes could reflect a recall bias.

  4. Soot and palynologic analysis of Manson impact-related strata (Upper Cretaceous) of Iowa and South Dakota, USA

    USGS Publications Warehouse

    Varricchio, D.J.; Raven, R.F.; Wolbach, W.S.; Elsik, W.C.; Witzke, B.J.

    2009-01-01

    The Campanian Manson impact structure of Iowa represents the best-preserved, large-diameter complex crater within the continental U.S. To assess the timing and potential mode of crater infilling and the possible presence of an impact event horizon, we analyzed samples from both within and distal to the impact structure for their elemental carbon, soot and palynomorphs. Within the impact structure, identifiable soot occurred in fragmented impact breccia and suevite but not in lower impact-melt breccia. Although most of this soot likely represents reworking of material from older Cretaceous marine shales, one high soot concentration occurs with melt material in a Keweenawan Shale-Phanerozoic clast breccia mix. This represents the first association of soot and impact-generated materials within an impact structure and the best sample candidate for Manson impact-generated soot. No palynomorphs occurred in the impact melt breccia. Overlying suevite (Keweenawan Shale clast breccia) of the central peak yielded sparse and thermally altered palynomorphs, indicating deposition prior to full cooling of the crater debris. Presence of easily degraded soot also argues for rapid backfilling of the crater. Distal samples from South Dakota represent the Sharon Springs and Crow Creek members of the Pierre Shale 230 km northwest of the Manson impact structure. Although containing shocked grains, the Crow Creek preserves no soot. In contrast, the Sharon Springs, generally considered as predating the Manson impact, has significant soot quantities. Palynomorphs differ markedly across the unconformity separating the two members with the Crow Creek containing more terrestrial forms, normapolles, and older reworked palynomorphs, consistent with a terrestrial impact to the east. Origin of the Sharon Springs soot remains unclear. Given soot occurrence within four of the five Cretaceous marine units sampled, the relatively shallow, anoxic bottom conditions of the Western Interior Cretaceous

  5. Laser-diagnostic mapping of temperature and soot statistics in a 2-m diameter turbulent pool fire

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kearney, Sean P.; Grasser, Thomas W.

    We present spatial profiles of temperature and soot-volume-fraction statistics from a sooting 2-m base diameter turbulent pool fire, burning a 10%-toluene / 90%-methanol fuel mixture. Dual-pump coherent anti-Stokes Raman scattering and laser-induced incandescence are utilized to obtain radial profiles of temperature and soot probability density functions (pdf) as well as estimates of temperature/soot joint statistics at three vertical heights above the surface of the methanol/toluene fuel pool. Results are presented both in the fuel vapor-dome region at ¼ base diameter and in the actively burning region at ½ and ¾ diameters above the fuel surface. The spatial evolution of themore » soot and temperature pdfs is discussed and profiles of the temperature and soot mean and rms statistics are provided. Joint temperature/soot statistics are presented as spatially resolved conditional averages across the fire plume, and in terms of a joint pdf obtained by including measurements from multiple spatial locations.« less

  6. Laser-diagnostic mapping of temperature and soot statistics in a 2-m diameter turbulent pool fire

    DOE PAGES

    Kearney, Sean P.; Grasser, Thomas W.

    2017-08-10

    We present spatial profiles of temperature and soot-volume-fraction statistics from a sooting 2-m base diameter turbulent pool fire, burning a 10%-toluene / 90%-methanol fuel mixture. Dual-pump coherent anti-Stokes Raman scattering and laser-induced incandescence are utilized to obtain radial profiles of temperature and soot probability density functions (pdf) as well as estimates of temperature/soot joint statistics at three vertical heights above the surface of the methanol/toluene fuel pool. Results are presented both in the fuel vapor-dome region at ¼ base diameter and in the actively burning region at ½ and ¾ diameters above the fuel surface. The spatial evolution of themore » soot and temperature pdfs is discussed and profiles of the temperature and soot mean and rms statistics are provided. Joint temperature/soot statistics are presented as spatially resolved conditional averages across the fire plume, and in terms of a joint pdf obtained by including measurements from multiple spatial locations.« less

  7. Effect of traffic and driving characteristics on morphology of atmospheric soot particles at freeway on-ramps.

    PubMed

    China, Swarup; Salvadori, Neila; Mazzoleni, Claudio

    2014-03-18

    Vehicles represent a major source of soot in urban environments. Knowledge of the morphology and mixing of soot particles is fundamental to understand their potential health and climatic impacts. We investigate 5738 single particles collected at six different cloverleaf freeway on-ramps in Southern Michigan, using 2D images from scanning electron microscopy. Of those, 3364 particles are soot. We present an analysis of the morphological and mixing properties of those soot particles. The relative abundance of soot particles shows a positive association with traffic density (number of vehicles per minute). A classification of the mixing state of freshly emitted soot particles shows that most of them are bare (or thinly coated) (72%) and some are partly coated (22%). We find that the fractal dimension of soot particles (one of the most relevant morphological descriptors) varies from site to site, and increases with increasing vehicle specific power that represents the driving/engine load conditions, and with increasing percentage of vehicles older than 15 years. Our results suggest that driving conditions, and vehicle age and type have significant influence on the morphology of soot particles.

  8. A New Paradigm in Modeling and Simulations of Complex Oxidation Chemistry Using a Statistical Approach

    DTIC Science & Technology

    2009-03-31

    8. This range encompasses diesel , HCCI and gas turbine engines , including cold ignition; and NOx , CO and soot pollutant formation in the lean and...equivalence ratios from 0.125 to 8. This range encompasses diesel , HCCI and gas turbine engines , including cold ignition; and NOx , CO and soot pollutant...California Institute of Technology Mechanical Engineering Department Pasadena CA 91125 i Abstract This report describes a study

  9. Variability in morphology, hygroscopicity, and optical properties of soot aerosols during atmospheric processing

    PubMed Central

    Zhang, Renyi; Khalizov, Alexei F.; Pagels, Joakim; Zhang, Dan; Xue, Huaxin; McMurry, Peter H.

    2008-01-01

    The atmospheric effects of soot aerosols include interference with radiative transfer, visibility impairment, and alteration of cloud formation and are highly sensitive to the manner by which soot is internally mixed with other aerosol constituents. We present experimental studies to show that soot particles acquire a large mass fraction of sulfuric acid during atmospheric aging, considerably altering their properties. Soot particles exposed to subsaturated sulfuric acid vapor exhibit a marked change in morphology, characterized by a decreased mobility-based diameter but an increased fractal dimension and effective density. These particles experience large hygroscopic size and mass growth at subsaturated conditions (<90% relative humidity) and act efficiently as cloud-condensation nuclei. Coating with sulfuric acid and subsequent hygroscopic growth enhance the optical properties of soot aerosols, increasing scattering by ≈10-fold and absorption by nearly 2-fold at 80% relative humidity relative to fresh particles. In addition, condensation of sulfuric acid is shown to occur at a similar rate on ambient aerosols of various types of a given mobility size, regardless of their chemical compositions and microphysical structures. Representing an important mechanism of atmospheric aging, internal mixing of soot with sulfuric acid has profound implications on visibility, human health, and direct and indirect climate forcing. PMID:18645179

  10. CoFlame: A refined and validated numerical algorithm for modeling sooting laminar coflow diffusion flames

    NASA Astrophysics Data System (ADS)

    Eaves, Nick A.; Zhang, Qingan; Liu, Fengshan; Guo, Hongsheng; Dworkin, Seth B.; Thomson, Murray J.

    2016-10-01

    Mitigation of soot emissions from combustion devices is a global concern. For example, recent EURO 6 regulations for vehicles have placed stringent limits on soot emissions. In order to allow design engineers to achieve the goal of reduced soot emissions, they must have the tools to so. Due to the complex nature of soot formation, which includes growth and oxidation, detailed numerical models are required to gain fundamental insights into the mechanisms of soot formation. A detailed description of the CoFlame FORTRAN code which models sooting laminar coflow diffusion flames is given. The code solves axial and radial velocity, temperature, species conservation, and soot aggregate and primary particle number density equations. The sectional particle dynamics model includes nucleation, PAH condensation and HACA surface growth, surface oxidation, coagulation, fragmentation, particle diffusion, and thermophoresis. The code utilizes a distributed memory parallelization scheme with strip-domain decomposition. The public release of the CoFlame code, which has been refined in terms of coding structure, to the research community accompanies this paper. CoFlame is validated against experimental data for reattachment length in an axi-symmetric pipe with a sudden expansion, and ethylene-air and methane-air diffusion flames for multiple soot morphological parameters and gas-phase species. Finally, the parallel performance and computational costs of the code is investigated.

  11. Changes of ns-soot mixing states and shapes in an urban area during CalNex

    NASA Astrophysics Data System (ADS)

    Adachi, Kouji; Buseck, Peter R.

    2013-05-01

    Aerosol particles from megacities influence the regional and global climate as well as the health of their occupants. We used transmission electron microscopes (TEMs) to study aerosol particles collected from the Los Angeles area during the 2010 CalNex campaign. We detected major amounts of ns-soot, defined as consisting of carbon nanospheres, sulfate, sea salt, and organic aerosol (OA) and lesser amounts of brochosome particles from leaf hoppers. Ns-soot-particle shapes, mixing states, and abundances varied significantly with sampling times and days. Within plumes having high CO2 concentrations, much ns-soot was compacted and contained a relatively large number of carbon nanospheres. Ns-soot particles from both CalNex samples and Mexico City, the latter collected in 2006, had a wide range of shapes when mixed with other aerosol particles, but neither sets showed spherical ns-soot nor the core-shell configuration that is commonly used in optical calculations. Our TEM observations and light-absorption calculations of modeled particles indicate that, in contrast to ns-soot particles that are embedded within other materials or have the hypothesized core-shell configurations, those attached to other aerosol particles hardly enhance their light absorption. We conclude that the ways in which ns-soot mixes with other particles explain the observations of smaller light amplification by ns-soot coatings than model calculations during the CalNex campaign and presumably in other areas.

  12. Multicomponent droplet combustion and soot formation in microgravity

    NASA Technical Reports Server (NTRS)

    Avedisian, C. Thomas

    1995-01-01

    Most practical fuels which are burned in combustion-powered devices, stationary power plants, and incinerators are multicomponent in nature. The differing properties of fuels effects the combustion behavior of the blend. Blending can be useful to achieve desired ends, such as increasing burning rates and reducing extinction diameter and soot formation. Of these, particulate emissions is one of the most important concerns because of its impact on the environment. It is also the least understood and most complicated aspect of droplet combustion. Because of this fact, a well characterized flow field and simplified flame shape can improve the understanding of soot formation during droplet combustion. The simplest flame shape to analyze for a droplet, while still maintaining the integrity of the droplet geometry with its inherent unsteadiness, is spherical with its associated one-dimensional flow field. This project will concern soot formation in microgravity droplet flames and some parameters that effect it. Because the project has not yet begun, this paper will briefly review some related results on this subject.

  13. Simultaneous schlieren photography and soot foil in the study of detonation phenomena

    NASA Astrophysics Data System (ADS)

    Kellenberger, Mark; Ciccarelli, Gaby

    2017-10-01

    The use of schlieren photography has been essential in unravelling the complex nature of high-speed combustion phenomena, but its line-of-sight integration makes it difficult to decisively determine the nature of multi-dimensional combustion wave propagation. Conventional schlieren alone makes it impossible to determine in what plane across the channel an observed structure may exist. To overcome this, a technique of simultaneous high-speed schlieren photography and soot foils was demonstrated that can be applied to the study of detonation phenomena. Using a kerosene lamp, soot was deposited on a glass substrate resulting in a semi-transparent sheet through which schlieren source light could pass. In order to demonstrate the technique, experiments were carried out in mixtures of stoichiometric hydrogen-oxygen at initial pressures between 10 and 15 kPa. Compared to schlieren imaging obtained without a sooted foil, high-speed video results show schlieren images with a small reduction of contrast with density gradients remaining clear. Areas of high temperature cause soot lofted from the foil to incandescence strongly, resulting in the ability to track hot spots and flame location. Post-processing adjustments were demonstrated to make up for camera sensitivity limitations to enable viewing of schlieren density gradients. High-resolution glass soot foils were produced that enable direct coupling of schlieren video to triple-point trajectories seen on the soot foils, allowing for the study of three-dimensional propagation mechanisms of detonation waves.

  14. Ambient Observations of the Soot Aging Process during the SHARP Intensive Field Campaign

    NASA Astrophysics Data System (ADS)

    Reed, C.; Collins, D. R.; Khalizov, A. F.; Zheng, J.; Zhang, R.

    2009-12-01

    Soot aerosols affect climate both directly through absorption of solar radiation and indirectly by potentially serving as cloud condensation nuclei. Among the sources of uncertainty surrounding the effects of soot aerosol on the environment is the lack of scientific insight into the soot aging process, in which soot particles develop a coating of secondary species such as sulfates, ammonium, nitrate, and organics. Such processes may alter the behavior of soot by modifying particle morphology over time leading to changes in chemical, physical and scattering properties of the aerosol. However, it is often difficult to quantify such processes in the ambient environment due to the complex composition and spatial and temporal variability of the atmospheric aerosol. In order to better understand the effects of the environment on soot particles, it is desirable to study the processes responsible for their transformation in the ambient air without influence from variability in source region and history prior to sampling. To achieve this, the overall soot aging process in the ambient environment was physically isolated utilizing environmental chambers. Chamber measurements were conducted on the Moody Tower at the University of Houston using The Ambient Aerosol Chamber for Evolution Studies (AACES) during the SHARP campaign. AACES is a roughly cubical chamber constructed of a rigid acrylic outer shell, which transmits UV radiation both in the UV-B and UV-A ranges. FEP Teflon lines the inside of the chamber on all sides and the top, while expanded-PTFE (ePTFE) Teflon is used on the bottom of the chamber. The fibrous structure of the ePTFE acts as a barrier to particulates, while allowing gas molecules to move virtually unimpeded from the surrounding air into the chamber, creating an environment inside the chamber that is initially free of particles and continuously mimics the local ambient air. In order to study the effects of the soot aging process, a non-premixed propane

  15. Soot and Spectral Radiation Modeling for a High-Pressure Turbulent Spray Flame

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ferreryo-Fernandez, Sebastian; Paul, Chandan; Sircar, Arpan

    Simulations are performed of a transient high-pressure turbulent n-dodecane spray flame under engine-relevant conditions. An unsteady RANS formulation is used, with detailed chemistry, a semi-empirical two-equation soot model, and a particle-based transported composition probability density function (PDF) method to account for unresolved turbulent fluctuations in composition and temperature. Results from the PDF model are compared with those from a locally well-stirred reactor (WSR) model to quantify the effects of turbulence-chemistry-soot interactions. Computed liquid and vapor penetration versus time, ignition delay, and flame lift-off height are in good agreement with experiment, and relatively small differences are seen between the WSR andmore » PDF models for these global quantities. Computed soot levels and spatial soot distributions from the WSR and PDF models show large differences, with PDF results being in better agreement with experimental measurements. An uncoupled photon Monte Carlo method with line-by-line spectral resolution is used to compute the spectral intensity distribution of the radiation leaving the flame. This provides new insight into the relative importance of molecular gas radiation versus soot radiation, and the importance of turbulent fluctuations on radiative heat transfer.« less

  16. Soot Particle Studies - Instrument Inter-Comparison – Project Overview

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cross, E.; Sedlacek, A.; Onasch, T. B.

    2010-03-06

    An inter-comparison study of instruments designed to measure the microphysical and optical properties of soot particles was completed. The following mass-based instruments were tested: Couette Centrifugal Particle Mass Analyzer (CPMA), Time-of-Flight Aerosol Mass Spectrometer - Scanning Mobility Particle Sizer (AMS-SMPS), Single Particle Soot Photometer (SP2), Soot Particle-Aerosol Mass Spectrometer (SP-AMS) and Photoelectric Aerosol Sensor (PAS2000CE). Optical instruments measured absorption (photoacoustic, interferometric, and filter-based), scattering (in situ), and extinction (light attenuation within an optical cavity). The study covered an experimental matrix consisting of 318 runs that systematically tested the performance of instruments across a range of parameters including: fuel equivalence ratiomore » (1.8 {le} {phi} {le} 5), particle shape (mass-mobility exponent (D{sub f m}), 2.0 {le} D{sub f m} {le} 3.0), particle mobility size (30 {le} d{sub m} {le} 300 nm), black carbon mass (0.07 {le} m{sub BC} {le} 4.2 fg) and particle chemical composition. In selected runs, particles were coated with sulfuric acid or dioctyl sebacate (DOS) (0.5 {le} {Delta}r{sub ve} {le} 201 nm) where {Delta}r{sub ve} is the change in the volume equivalent radius due to the coating material. The effect of non-absorbing coatings on instrument response was determined. Changes in the morphology of fractal soot particles were monitored during coating and denuding processes and the effect of particle shape on instrument response was determined. The combination of optical and mass based measurements was used to determine the mass specific absorption coefficient for denuded soot particles. The single scattering albedo of the particles was also measured. An overview of the experiments and sample results are presented.« less

  17. On the fractal morphology of combustion-generated soot aggregates

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Koylu, U.O.

    1995-12-31

    The fractal properties of soot aggregates were investigated using ex-situ and in-situ experimental methods as well as computer simulations. Ex-situ experiments involved thermophoretic sampling and analysis by transmission electron microscopy (TEM), while in-situ measurements employed angular static light scattering and data inversion based on Rayleigh-Debye-Gans (RDG) approximation. Computer simulations used a sequential algorithm which mimics mass fractal-like structures. So from a variety of hydrocarbon-fueled laminar and turbulent nonpremixed flame environments were considered in the present study. The TEM analysis of projected soot images sampled from fuel-rich conditions of buoyant and weakly-buoyant laminar flames indicated that the fractal dimension of sootmore » was relatively independent of position in flames, fuel type and flame condition. These measurements yielded an average fractal dimension of 1.8, although other structure parameters such as the primary particle diameters and number of primary particles in aggregates had wide range of values. Fractal prefactor (lacunarity) was also measured for soot sampled from the fuel-lean conditions of turbulent flames, considering the actual morphology by tilting the samples during TEM analysis. These measurements yielded a fractal dimension of 1.65 and a lacunarity of 8.5, with experimental uncertainties (95% confidence) of 0.08 and 0.5, respectively. Relationships between the actual and projected structure properties of soot were also developed by combining TEM observations with numerical simulations. Practical approximate formulae were suggested to find radius of gyration of an aggregate from its maximum dimension, and number of primary particles in an aggregate from projected area. Finally, the fractal dimension and lacunarity of soot were obtained using light scattering for the same conditions of the above TEM measurements.« less

  18. Model compound study of the pathways for aromatic hydrocarbon formation in soot.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tomczyk, N. A.; Hunt, J. E.; Winans, R. E.

    2002-04-29

    To explore the mechanisms for formation of aromatic hydrocarbons as precursors to soot, a model system using combustion of biphenyl in a fuel rich flame is studied. The soots acquired at three different temperatures are solvent extracted and the extract characterized by both GCMS and high resolution mass spectrometry. A description of the NMR results for the whole soots has been published (1). The production of most products could be rationalized from the coupling of biphenyls and subsequent aromatic species and the addition of acetylenes to existing aromatic molecules. Early work by Badger on pyrolysis of hydrocarbons is used inmore » developing these schemes (2). The reaction schemes to produce larger aromatic hydrocarbons will be discussed. Richter and Howard have discussed in detail potential reaction mechanisms in the formation of aromatics as precursors to soot (3).« less

  19. Particulate Matter from Both Heavy Fuel Oil and Diesel Fuel Shipping Emissions Show Strong Biological Effects on Human Lung Cells at Realistic and Comparable In Vitro Exposure Conditions

    PubMed Central

    Dilger, Marco; Paur, Hanns-Rudolf; Schlager, Christoph; Mülhopt, Sonja; Diabaté, Silvia; Weiss, Carsten; Stengel, Benjamin; Rabe, Rom; Harndorf, Horst; Torvela, Tiina; Jokiniemi, Jorma K.; Hirvonen, Maija-Riitta; Schmidt-Weber, Carsten; Traidl-Hoffmann, Claudia; BéruBé, Kelly A.; Wlodarczyk, Anna J.; Prytherch, Zoë; Michalke, Bernhard; Krebs, Tobias; Prévôt, André S. H.; Kelbg, Michael; Tiggesbäumker, Josef; Karg, Erwin; Jakobi, Gert; Scholtes, Sorana; Schnelle-Kreis, Jürgen; Lintelmann, Jutta; Matuschek, Georg; Sklorz, Martin; Klingbeil, Sophie; Orasche, Jürgen; Richthammer, Patrick; Müller, Laarnie; Elsasser, Michael; Reda, Ahmed; Gröger, Thomas; Weggler, Benedikt; Schwemer, Theo; Czech, Hendryk; Rüger, Christopher P.; Abbaszade, Gülcin; Radischat, Christian; Hiller, Karsten; Buters, Jeroen T. M.; Dittmar, Gunnar; Zimmermann, Ralf

    2015-01-01

    Background Ship engine emissions are important with regard to lung and cardiovascular diseases especially in coastal regions worldwide. Known cellular responses to combustion particles include oxidative stress and inflammatory signalling. Objectives To provide a molecular link between the chemical and physical characteristics of ship emission particles and the cellular responses they elicit and to identify potentially harmful fractions in shipping emission aerosols. Methods Through an air-liquid interface exposure system, we exposed human lung cells under realistic in vitro conditions to exhaust fumes from a ship engine running on either common heavy fuel oil (HFO) or cleaner-burning diesel fuel (DF). Advanced chemical analyses of the exhaust aerosols were combined with transcriptional, proteomic and metabolomic profiling including isotope labelling methods to characterise the lung cell responses. Results The HFO emissions contained high concentrations of toxic compounds such as metals and polycyclic aromatic hydrocarbon, and were higher in particle mass. These compounds were lower in DF emissions, which in turn had higher concentrations of elemental carbon (“soot”). Common cellular reactions included cellular stress responses and endocytosis. Reactions to HFO emissions were dominated by oxidative stress and inflammatory responses, whereas DF emissions induced generally a broader biological response than HFO emissions and affected essential cellular pathways such as energy metabolism, protein synthesis, and chromatin modification. Conclusions Despite a lower content of known toxic compounds, combustion particles from the clean shipping fuel DF influenced several essential pathways of lung cell metabolism more strongly than particles from the unrefined fuel HFO. This might be attributable to a higher soot content in DF. Thus the role of diesel soot, which is a known carcinogen in acute air pollution-induced health effects should be further investigated. For the

  20. Laboratory measurements in a turbulent, swirling flow. [measurement of soot inside a flame-tube burner

    NASA Technical Reports Server (NTRS)

    Hoult, D. P.

    1979-01-01

    Measurements of soot inside a flame-tube burner using a special water-flushed probe are discussed. The soot is measured at a series of points at each burner, and upon occasion gaseous constitutents NO, CO, hydrocarbons, etc., were also measured. Four geometries of flame-tube burners were studied, as well as a variety of different fuels. The role of upstream geometry on the downstream pollutant formation was studied. It was found that the amount of soot formed in particularly sensitive to how aerodynamically clean the configuration of the burner is upstream of the injector swirl vanes. The effect of pressure on soot formation was also studied. It was found that beyond a certain Reynolds number, the peak amount of soot formed in the burner is constant.

  1. Molecular modelling investigations on the possibility of phenanthrene dimers to be the primary nuclei of soot

    NASA Astrophysics Data System (ADS)

    Wei, Mingrui; Wu, Sheng; Li, Fan; Zhang, Dongju; Zhang, Tingting; Guo, Guanlun

    2017-11-01

    Pyrene dimerisation was successfully used to model the beginning of soot nucleation in some simulation models. However, the quantum mechanics (QM) calculations proved that the binding energy of a PAH dimer with three six-member rings was similar to that of a pyrene dimer. Meanwhile, the high concentration of phenanthrene at flame conditions indicated high probability of collisions among them. The small difference of the binding energy and high concentration indicated that PAHs structurally smaller than pyrene also could be involved in soot inception. Hence, binary collisions of phenanthrene were simulated to find out whether phenanthrene dimers can serve as soot primary nuclei or not by using non-equilibrium molecular dynamics (MD). Three temperatures, six collision orientations and 155 initial translational velocities (ITVs) were considered. The results indicated that the number of dimers with lifetime over 10 ps which can serve as soot nuclei decreased from 52 at 1000 K to 17 at 1600 K, and further to 6 at 2400 K, which means that low temperature was more favourable for phenanthrene to form soot nuclei. Meanwhile, no soot nuclei were formed at the high velocity region (HVR), compared to 43 and 9 at low and middle velocity regions (LVR and MVR), respectively, when temperature was 1000 K. Also, no soot nuclei were formed at HVR when the temperature was raised to 1600 K and 2400 K. This indicated that HVR was unfavourable for phenanthrene to form soot nuclei. The results computationally further illustrated that small PAHs such as phenanthrene could serve as soot primary nuclei, since they have similar mole fractions in some flames. This may be useful for future soot simulation models.

  2. Planar measurements of soot volume fraction and OH in a JP-8 pool fire

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Henriksen, Tara L.; Ring, Terry A.; Eddings, Eric G.

    2009-07-15

    The simultaneous measurement of soot volume fraction by laser induced incandescence (LII) and qualitative imaging of OH by laser induced fluorescence (LIF) was performed in a JP-8 pool fire contained in a 152 mm diameter pan. Line of sight extinction was used to calibrate the LII system in a laminar flame, and to provide an independent method of measuring average soot volume fraction in the turbulent flame. The presence of soot in the turbulent flame was found to be approximately 50% probable, resulting in high levels of optical extinction, which increased slightly through the flame from approximately 30% near themore » base, to approximately 50% at the tip. This high soot loading pushes both techniques toward their detection limit. Nevertheless, useful accuracy was obtained, with the LII measurement of apparent extinction in the turbulent flame being approximately 21% lower than a direct measurement, consistent with the influence of signal trapping. The axial and radial distributions of soot volume fraction are presented, along with PDFs of volume fraction, and new insight into the behavior of soot sheets in pool fires are sought from the simultaneous measurements of OH and LII. (author)« less

  3. Reconstruction of atmospheric soot history in inland regions from lake sediments over the past 150 years

    PubMed Central

    Han, Y. M.; Wei, C.; Huang, R.-J.; Bandowe, B. A. M.; Ho, S. S. H.; Cao, J. J.; Jin, Z. D.; Xu, B. Q.; Gao, S. P.; Tie, X. X.; An, Z. S.; Wilcke, W.

    2016-01-01

    Historical reconstruction of atmospheric black carbon (BC, in the form of char and soot) is still constrained for inland areas. Here we determined and compared the past 150-yr records of BC and polycyclic aromatic compounds (PACs) in sediments from two representative lakes, Huguangyan (HGY) and Chaohu (CH), in eastern China. HGY only receives atmospheric deposition while CH is influenced by riverine input. BC, char, and soot have similar vertical concentration profiles as PACs in both lakes. Abrupt increases in concentrations and mass accumulation rates (MARs) of soot have mainly occurred since ~1950, the establishment of the People’s Republic of China, when energy usage changed to more fossil fuel contributions reflected by the variations in the concentration ratios of char/soot and individual PACs. In HGY, soot MARs increased by ~7.7 times in the period 1980–2012 relative to the period 1850–1950. Similar increases (~6.7 times) were observed in CH. The increase in soot MARs is also in line with the emission inventory records in the literature and the fact that the submicrometer-sized soot particles can be dispersed regionally. The study provides an alternative method to reconstruct the atmospheric soot history in populated inland areas. PMID:26750586

  4. Quantifying uncertainty in soot volume fraction estimates using Bayesian inference of auto-correlated laser-induced incandescence measurements

    NASA Astrophysics Data System (ADS)

    Hadwin, Paul J.; Sipkens, T. A.; Thomson, K. A.; Liu, F.; Daun, K. J.

    2016-01-01

    Auto-correlated laser-induced incandescence (AC-LII) infers the soot volume fraction (SVF) of soot particles by comparing the spectral incandescence from laser-energized particles to the pyrometrically inferred peak soot temperature. This calculation requires detailed knowledge of model parameters such as the absorption function of soot, which may vary with combustion chemistry, soot age, and the internal structure of the soot. This work presents a Bayesian methodology to quantify such uncertainties. This technique treats the additional "nuisance" model parameters, including the soot absorption function, as stochastic variables and incorporates the current state of knowledge of these parameters into the inference process through maximum entropy priors. While standard AC-LII analysis provides a point estimate of the SVF, Bayesian techniques infer the posterior probability density, which will allow scientists and engineers to better assess the reliability of AC-LII inferred SVFs in the context of environmental regulations and competing diagnostics.

  5. Mapping and quantifying isomer sets of hydrocarbons (≥ C12) in diesel exhaust, lubricating oil and diesel fuel samples using GC × GC-ToF-MS

    NASA Astrophysics Data System (ADS)

    Alam, Mohammed S.; Zeraati-Rezaei, Soheil; Liang, Zhirong; Stark, Christopher; Xu, Hongming; MacKenzie, A. Rob; Harrison, Roy M.

    2018-05-01

    Airborne particles and vapours, like many other environmental samples including water, soils and sediments, contain complex mixtures of hydrocarbons, often deriving from crude oil either before or after fractionation into fuels, lubricants and feedstocks. Comprehensive 2D gas chromatography time-of-flight mass spectrometry (GC × GC-ToF-MS), offers a very powerful technique that separates and identifies many compounds in complicated hydrocarbon mixtures. However, quantification and identification of individual constituents at high ionization energies would require hundreds of expensive (when available) standards for calibration. Although the precise chemical structure of hydrocarbons does matter for their environmental impact and fate, strong similarities can be expected for compounds having very similar chemical structures and carbon numbers. There is, therefore, a clear benefit in an analytical technique which is specific enough to separate different classes of compounds and to distinguish homologous series while avoiding the need to handle each isomer individually. Varying EI (electron impact) ionization mass spectrometry significantly enhances the identification of individual isomers and homologous compound groups, which we refer to as isomer sets. Advances are reported in mapping and quantifying isomer sets of hydrocarbons (≥ C12) in diesel fuel, lubricating oil and diesel exhaust emissions. By using this analysis we report mass closures of ca. 90 and 75 % for diesel fuel and lubricating oil, and identify 85 and 75 % of the total ion current for gas- and particulate-phase diesel exhaust emissions.

  6. Characterization of Air Plane Soot Surrogates using Raman spectroscopy and laser ablation techniques

    NASA Astrophysics Data System (ADS)

    Chazallon, Bertrand; Ortega, Ismael Kenneth; Ikhenazene, Raouf; Pirim, Claire; Carpentier, Yvain; Irimiea, Cornelia; Focsa, Cristian; Ouf, François-Xavier

    2016-04-01

    Aviation alters the composition of the atmosphere globally and can thus drive climate change and ozone depletion [1]. Aircraft exhaust plumes contain species (gases and soot particles) produced by the combustion of kerosene with ambient air in the combustion chamber of the engine. Soot particles emitted by air-planes produce persistent contrails in the upper troposphere in ice-supersaturated air masses that contribute to cloudiness and impact the radiative properties of the atmosphere. These aerosol-cloud interactions represent one of the largest sources of uncertainty in global climate models [2]. Though the formation of atmospheric ice particles has been studied for many years [3], there are still numerous opened questions on nucleation properties of soot particles [4], as the ice nucleation experiments showed a large spread in results depending on the nucleation mode chosen and origin of the soot produced. The reasons behind these discrepancies reside in the different physico-chemical properties (composition, structure) of soot particles produced in different conditions, e.g., with respect to fuel or combustion techniques. In this work, we use Raman microscopy (514 and 785 nm excitation wavelengths) and ablation techniques (Secondary Ions Mass Spectrometry, and Laser Desorption Mass Spectrometry) to characterize soot particle surrogates produced from a CAST generator (propane fuel, four different global equivalence ratios). They are produced as analogues of air-plane soot collected at different engine regimes (PowerJet SaM-146 turbofan) simulating a landing and take-off (LTO) cycle (MERMOSE project (http://mermose.onera.fr/)) [6]. The spectral parameters of the first-order Raman bands of these soot samples are analyzed using a de-convolution approach described by Sadezky et al. (2005) [5]. A systematic Raman analysis is carried out to select a number of parameters (laser wavelength, irradiance at sample, exposure time) that will alter the sample and the

  7. A unique approach to determine the ice nucleating potential of soot-containing aerosol from biomass combustion

    NASA Astrophysics Data System (ADS)

    Levin, E. J.; McMeeking, G. R.; McCluskey, C.; DeMott, P. J.; Kreidenweis, S. M.

    2013-12-01

    Ice nucleating particles (INP) play a crucial role in cloud and precipitation development in mixed phase clouds by catalyzing ice formation at temperatures warmer than -36 C. Despite their importance, however, there is still considerable uncertainty as to the sources and chemical nature of INP. Water insoluble particles such as mineral dust and certain biological aerosols have been shown to be efficient ice nuclei, and soot particles have also been suggested as potential INP. Biomass burning, such as wildfires and prescribed burning, is a large contributor to atmospheric soot concentrations, and could therefore be a potentially important source of INP. Both laboratory and field studies have detected enhanced INP concentrations in smoke plumes; however, the chemical composition of these INP is still uncertain as fires emit and loft a complex mixture of aerosol particles. In this work we employ a novel approach to selectively remove soot aerosol from the sample stream to determine the specific contribution of soot to INP concentrations. A number of commonly consumed biomass fuels were burned in the U.S. Forest Service combustion laboratory during the FLAME-4 (Fire Laboratory At Missoula Experiment - 4) study. Number concentrations of INP acting in the condensation and immersion freezing modes and total aerosol greater than 500 nm in diameter (N500) were measured using the Colorado State University Continuous Flow Diffusion Chamber (CFDC). To determine the contribution of soot to INP concentrations, the sample stream was passed through a Single Particle Soot Photometer (SP2; Droplet Measurement Technologies) which employs laser induced incandescence (LII) to detect soot containing particles and total soot mass. During LII, soot containing particles are vaporized and removed from the sample while non-soot containing particles pass through the instrument unaffected. By sampling the exhaust of the SP2 with the CFDC and alternately cycling laser power on and off we were

  8. Effects of Retrofitting Emission Control Systems on all In-Use Heavy Diesel Trucks

    NASA Astrophysics Data System (ADS)

    Millstein, D.; Harley, R. A.

    2009-12-01

    Diesel exhaust is now the largest source of nitrogen oxide (NOx) emissions nationally in the US, and contributes significantly to emissions of fine particulate black carbon (soot) as well. New national standards call for dramatically lower emissions of exhaust particulate matter (PM) and NOx from new diesel engines starting in 2007 and 2010, respectively. Unfortunately it will take decades for the cleaner new engines to replace those currently in service on existing heavy-duty trucks. The state of California recently adopted a rule to accelerate fleet turnover in the heavy-duty truck sector, requiring that all in-use trucks meet the new exhaust PM standards by 2014. This will entail retrofit of diesel particle filters or replacement for over a million existing diesel engines. Diesel particle filters can replace the muffler on existing trucks, and there is extensive experience with retrofit of this control equipment on public sector fleets such as diesel-powered transit buses. Nitrogen dioxide (NO2) is used as an oxidizing agent to remove carbon particles from the particle filter, to prevent it from becoming plugged. To create the needed NO2, NOx already present in engine exhaust as nitric oxide (NO) is deliberately oxidized to NO2 upstream of the particle filter using a platinum catalyst. The NO2/NOx ratio in exhaust emissions therefore increases to ~35% in comparison to much lower values (~5%) typical of older engines without particle filters. We evaluate the effects on air quality of increased use of diesel particle traps and NOx controls in southern California using the Community Multiscale Air Quality (CMAQ) model. Compared to a reference scenario without the retrofit program, we found black carbon concentrations decreased by ~20%, with small increases (4%) in ambient ozone concentrations. During summer, average NO2 concentrations decrease despite the increase in primary NO2 emissions - because total NOx emissions are reduced as part of a parallel but more

  9. Meteorological transport of continental soot to Antarctica?

    NASA Astrophysics Data System (ADS)

    Murphey, B. B.; Hogan, A. W.

    1992-01-01

    An impactor/concentrator/microdensitometer (ICM) instrument system has been constructed and calibrated. This system is sufficiently sensitive to measure the black (carbon soot) component of Antarctic aerosol with a sampling time of four hours. The impactor concentrator was exposed to Antarctic air at Ross Island in September 1987. Microdensitometer analysis of the collected specimens indicates that the maximum black aerosol concentration was observed concurrently with the arrival of the warmest air accompanying a cyclonic storm. This is similar to the concurrence of continental radon and lead isotopes with warm advection, measured on the Antarctic coast by Polian et al. (1986). It is possible that continental soot can be transported to the Antarctic coast several times each year by this mechanism.

  10. Shapes of Soot Particles Embedded in Organic Material and Sulfates

    NASA Astrophysics Data System (ADS)

    Adachi, K.; Buseck, P. R.

    2008-12-01

    Three-dimensional (3D) shapes of aerosol particles collected from Mexico City during the MILAGRO (Megacity Initiative: Local and Global Research Observations) campaign were analyzed using electron tomography (ET). Mexico City is a representative tropical megacity, where pollution is heavy and photochemical reaction is rapid. Its aerosol particles are of interest because of their effects on the regional and global climate and on health. We used ET to study soot particles that are embedded in organic material, commonly with sulfates, collected from Mexico City plumes. They comprise more than 50 % of the aerosol particles with aerodynamic diameters between 50 and 300 nm. ET combines a series of transmission electron microscope (TEM) images obtained in different viewing directions into representations that display the 3D digitized objects. By using the 3D data, we determined the volume ratios of the various component materials in individual internally mixed particles. In our samples, organic materials dominate, and soot and sulfate commonly occupy up to 10 volume %. The mean fractal dimension, which indicates the complexity of aggregates, of soot particles is 2.2 (± 0.2), suggesting that they retain their chain-like structure when embedded in organic material rather than being highly compacted. Their 3D images show that soot particles tend to be near the surface of the embedding particle rather than in the core, i.e., a core-shell model is inappropriate. Their morphological features indicate that the soot particles have lower absorption of sunlight by a few tens of percent relative to that of the compacted or concentrically coated particles assumed in current climate models.

  11. Structure and Soot Properties of Nonbuoyant Ethylene/Air Laminar Jet Diffusion Flames. Appendix I

    NASA Technical Reports Server (NTRS)

    Urban, D. L.; Yuan, Z.-G.; Sunderland, P. B.; Linteris, G. T.; Voss, J. E.; Lin, K.-C.; Dai, Z.; Sun, K.; Faeth, G. M.; Ross, Howard D. (Technical Monitor)

    2000-01-01

    The structure and soot properties of round, soot-emitting, nonbuoyant, laminar jet diffusion flames are described, based on long-duration (175-230/s) experiments at microgravity carried out on orbit In the Space Shuttle Columbia. Experiments] conditions included ethylene-fueled flames burning in still air at nominal pressures of 50 and 100 kPa and an ambient temperature of 300 K with luminous Annie lengths of 49-64 mm. Measurements included luminous flame shapes using color video imaging, soot concentration (volume fraction) distributions using deconvoluted laser extinction imaging, soot temperature distributions using deconvoluted multiline emission imaging, gas temperature distributions at fuel-lean (plume) conditions using thermocouple probes, not structure distributions using thermophoretic sampling and analysis by transmission electron microscopy, and flame radiation using a radiometer. The present flames were larger, and emitted soot men readily, than comparable observed during ground-based microgravity experiments due to closer approach to steady conditions resulting from the longer test times and the reduced gravitational disturbances of the space-based experiments.

  12. Detailed modeling analysis for soot formation and radiation in microgravity gas jet diffusion flames

    NASA Technical Reports Server (NTRS)

    Ku, Jerry C.; Tong, LI; Greenberg, Paul S.

    1995-01-01

    Radiation heat transfer in combustion systems has been receiving increasing interest. In the case of hydrocarbon fuels, a significant portion of the radiation comes from soot particles, justifying the need for detailed soot formation model and radiation transfer calculations. For laminar gas jet diffusion flames, results from this project (4/1/91 8/22/95) and another NASA study show that flame shape, soot concentration, and radiation heat fluxes are substantially different under microgravity conditions. Our emphasis is on including detailed soot transport models and a detailed solution for radiation heat transfer, and on coupling them with the flame structure calculations. In this paper, we will discuss the following three specific areas: (1) Comparing two existing soot formation models, and identifying possible improvements; (2) A simple yet reasonably accurate approach to calculating total radiative properties and/or fluxes over the spectral range; and (3) Investigating the convergence of iterations between the flame structure solver and the radiation heat transfer solver.

  13. A perspective on the range of gasoline compression ignition combustion strategies for high engine efficiency and low NOx and soot emissions: Effects of in-cylinder fuel stratification

    DOE PAGES

    Dempsey, Adam B.; Curran, Scott J.; Wagner, Robert M.

    2016-01-14

    Many research studies have shown that low temperature combustion in compression ignition engines has the ability to yield ultra-low NOx and soot emissions while maintaining high thermal efficiency. To achieve low temperature combustion, sufficient mixing time between the fuel and air in a globally dilute environment is required, thereby avoiding fuel-rich regions and reducing peak combustion temperatures, which significantly reduces soot and NOx formation, respectively. It has been demonstrated that achieving low temperature combustion with diesel fuel over a wide range of conditions is difficult because of its properties, namely, low volatility and high chemical reactivity. On the contrary, gasolinemore » has a high volatility and low chemical reactivity, meaning it is easier to achieve the amount of premixing time required prior to autoignition to achieve low temperature combustion. In order to achieve low temperature combustion while meeting other constraints, such as low pressure rise rates and maintaining control over the timing of combustion, in-cylinder fuel stratification has been widely investigated for gasoline low temperature combustion engines. The level of fuel stratification is, in reality, a continuum ranging from fully premixed (i.e. homogeneous charge of fuel and air) to heavily stratified, heterogeneous operation, such as diesel combustion. However, to illustrate the impact of fuel stratification on gasoline compression ignition, the authors have identified three representative operating strategies: partial, moderate, and heavy fuel stratification. Thus, this article provides an overview and perspective of the current research efforts to develop engine operating strategies for achieving gasoline low temperature combustion in a compression ignition engine via fuel stratification. In this paper, computational fluid dynamics modeling of the in-cylinder processes during the closed valve portion of the cycle was used to illustrate the opportunities

  14. A perspective on the range of gasoline compression ignition combustion strategies for high engine efficiency and low NOx and soot emissions: Effects of in-cylinder fuel stratification

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dempsey, Adam B.; Curran, Scott J.; Wagner, Robert M.

    Many research studies have shown that low temperature combustion in compression ignition engines has the ability to yield ultra-low NOx and soot emissions while maintaining high thermal efficiency. To achieve low temperature combustion, sufficient mixing time between the fuel and air in a globally dilute environment is required, thereby avoiding fuel-rich regions and reducing peak combustion temperatures, which significantly reduces soot and NOx formation, respectively. It has been demonstrated that achieving low temperature combustion with diesel fuel over a wide range of conditions is difficult because of its properties, namely, low volatility and high chemical reactivity. On the contrary, gasolinemore » has a high volatility and low chemical reactivity, meaning it is easier to achieve the amount of premixing time required prior to autoignition to achieve low temperature combustion. In order to achieve low temperature combustion while meeting other constraints, such as low pressure rise rates and maintaining control over the timing of combustion, in-cylinder fuel stratification has been widely investigated for gasoline low temperature combustion engines. The level of fuel stratification is, in reality, a continuum ranging from fully premixed (i.e. homogeneous charge of fuel and air) to heavily stratified, heterogeneous operation, such as diesel combustion. However, to illustrate the impact of fuel stratification on gasoline compression ignition, the authors have identified three representative operating strategies: partial, moderate, and heavy fuel stratification. Thus, this article provides an overview and perspective of the current research efforts to develop engine operating strategies for achieving gasoline low temperature combustion in a compression ignition engine via fuel stratification. In this paper, computational fluid dynamics modeling of the in-cylinder processes during the closed valve portion of the cycle was used to illustrate the opportunities

  15. Sulforaphane-stimulated phase II enzyme induction inhibits cytokine production by airway epithelial cells stimulated with diesel extract.

    PubMed

    Ritz, Stacey A; Wan, Junxiang; Diaz-Sanchez, David

    2007-01-01

    Airborne particulate pollutants, such as diesel exhaust particles, are thought to exacerbate lung and cardiovascular diseases through induction of oxidative stress. Sulforaphane, derived from cruciferous vegetables, is the most potent known inducer of phase II enzymes involved in the detoxification of xenobiotics. We postulated that sulforaphane may be able to ameliorate the adverse effects of pollutants by upregulating expression of endogenous antioxidant enzymes. Stimulation of bronchial epithelial cells with the chemical constituents of diesel particles result in the production of proinflammatory cytokines. We first demonstrated a role for phase II enzymes in regulating diesel effects by transfecting the airway epithelial cell line (BEAS-2B) with the sentinel phase II enzyme NAD(P)H: quinine oxidoreductase 1 (NQO1). IL-8 production in response to diesel extract was significantly reduced in these compared with untransfected cells. We then examined whether sulforaphane would stimulate phase II induction and whether this would thereby ablate the effect of diesel extracts on cytokine production. We verified that sulforaphane significantly augmented expression of the phase II enzyme genes GSTM1 and NQO1 and confirmed that sulforaphane treatment increased glutathione S-transferase activity in epithelial cells without inducing cell death or apoptosis. Sulforaphane pretreatment inhibited IL-8 production by BEAS-2B cells upon stimulation with diesel extract. Similarly, whereas diesel extract stimulated production of IL-8, granulocyte-macrophage colony-stimulating factor, and IL-1beta from primary human bronchial epithelial cells, sulforaphane pretreatment inhibited diesel-induced production of all of these cytokines. Our studies show that sulforaphane can mitigate the effect of diesel in respiratory epithelial cells and demonstrate the chemopreventative potential of phase II enzyme enhancement.

  16. Sources and burial fluxes of soot black carbon in sediments on the Mackenzie, Chukchi, and Bering Shelves

    NASA Astrophysics Data System (ADS)

    Yang, Weifeng; Guo, Laodong

    2018-03-01

    Black carbon (BC) has been recognized as a climate forcing and a major component in the global carbon budget. However, studies on BC in the Arctic Ocean remain scarce. We report here variations in the abundance, sources and burial fluxes of sedimentary soot black carbon (soot-BC) in the western Arctic Ocean. The soot-BC contents averaged 1.6 ± 0.3, 0.46 ± 0.04 and 0.56 ± 0.10 mg-C g-1 on the Mackenzie, Chukchi and Bering Shelves, respectively, accounting for 16.6%, 10.2% and 10.4% of the total organic carbon in surface sediment. Temporally, contents of soot-BC remained fairly stable before 1910, but increased rapidly after the 1970s on the Mackenzie Shelf, indicating enhanced source input related to warming. Comparable δ13C signatures of soot-BC (- 24.95‰ to - 24.57‰) to C3 plants pointed to a major biomass source of soot-BC to the Beaufort Sea. Soot-BC showed similar temporal patterns with large fluctuations in the Chukchi/Bering shelf regions, implying the same source terms for soot-BC in these areas. Two events with elevated soot-BC corresponded to a simultaneous increase in biomass combustion and fossil fuel (coal and oil) consumption in Asia. The similar temporal variability in sedimentary soot-BC between the Arctic shelves and Asian lakes and the comparable δ13C values manifested that anthropogenic emission from East Asia was an important source of soot-BC in the western Arctic and subarctic regions. The burial fluxes of soot-BC, estimated from both 137Cs- and 210Pb-derived sedimentation rates, were 2.43 ± 0.42 g-C m-2 yr-1 on the Mackenzie Shelf, representing an efficient soot-BC sink. Soot-BC showed an increase in buried fluxes from 0.56 ± 0.02 g-C m-2 yr-1 during 1963-1986 to 0.88 ± 0.05 g-C m-2 yr-1 after 1986 on the Chukchi Shelf, and from 1.00 ± 0.18 g-C m-2 yr-1 to 2.58 ± 1.70 g-C m-2 yr-1 on the Bering Shelf, which were consistent with recent anthropogenically enhanced BC input observed especially in Asia. Overall, the three Arctic

  17. Effects of morphology and wavelength on the measurement accuracy of soot volume fraction by laser extinction

    NASA Astrophysics Data System (ADS)

    Wang, Ya-fei; Huang, Qun-xing; Wang, Fei; Chi, Yong; Yan, Jian-hua

    2018-01-01

    A novel method to evaluate the quantitative effects of soot morphology and incident wavelength on the measurement accuracy of soot volume fraction, by the laser extinction (LE) technique is proposed in this paper. The results indicate that the traditional LE technique would overestimate soot volume fraction if the effects of morphology and wavelength are not considered. Before the agglomeration of isolated soot primary particles, the overestimation of the LE technique is in the range of 2-20%, and rises with increasing primary particle diameter and with decreasing incident wavelength. When isolated primary particles are agglomerated into fractal soot aggregates, the overestimation would exceed 30%, and rise with increasing primary particle number per soot aggregate, fractal dimension and fractal prefactor and with decreasing incident wavelength to a maximum value of 55%. Finally, based on these results above, the existing formula of the LE technique gets modified, and the modification factor is 0.65-0.77.

  18. Light absorbing material (soot) in rainwater and in aerosol particles in the Maldives

    NASA Astrophysics Data System (ADS)

    Granat, L.; EngströM, J. E.; Praveen, S.; Rodhe, H.

    2010-08-01

    Simultaneous measurements of soot (absorbing material at 528 nm) and inorganic ions in aerosol and precipitation at the Maldives Climate Observatory Hanimaadhoo during the period May 2005 to February 2007 have made it possible to calculate the washout ratio (WR) of these components as a measure of how efficiently they are scavenged by precipitation. On the basis of air trajectories the data have been separated into days with polluted air arriving from the Indian subcontinent in a northeasterly sector during winter and clean monsoon days with southerly flow from the Indian Ocean. The average soot concentration was a factor of 10 higher in the former situations. Despite considerable scatter for individual days, a systematic pattern emerged when the WR for the different components were compared with each other. During the monsoon season the WR for soot was similar to that of sulfate and other fine mode aerosol components, indicating that soot containing particles in these situations were efficient as cloud condensation nuclei. The origin of the light absorbing material during the monsoon season is unclear. During the polluted winter days, on the other hand, the WR for soot was three times smaller than that of sulfate. This indicates that, even after a travel time of several days, the soot containing particles from India have retained much of their hydrophobic property. The low WR and the infrequent rain during this season probably contribute to extending the atmospheric lifetime of soot well beyond several days. Surprisingly high concentrations of non-sea-salt calcium were measured during the monsoon season, substantially higher than during the winter season. The origin of these high values could be long-range transport from the Australian or African continents. Another possibility might be exopolymer gels derived from the ocean surface microlayer.

  19. Internally mixed soot, sulfates, and organic matter in aerosol particles from Mexico City

    NASA Astrophysics Data System (ADS)

    Adachi, K.; Buseck, P. R.

    2008-05-01

    Soot particles are major aerosol constituents that result from emissions of burning of fossil fuel and biomass. Because they both absorb sunlight and contribute to cloud formation, they are an influence on climate on local, regional, and global scales. It is therefore important to evaluate their optical and hygroscopic properties and those effects on the radiation budget. Those properties commonly change through reaction with other particles or gases, resulting in complex internal mixtures. Using transmission electron microscopy, we measured ~8000 particles (25 samples) with aerodynamic diameters from 0.05 to 0.3 μm that were collected in March 2006 from aircraft over Mexico City (MC) and adjacent areas. More than 50% of the particles consist of internally mixed soot, organic matter, and sulfate. Imaging combined with chemical analysis of individual particles show that many are coated, consist of aggregates, or both. Coatings on soot particles can amplify their light absorption, and coagulation with sulfates changes their hygroscopic properties, resulting in shorter lifetime. Our results suggest that a mixture of materials from multiple sources such as vehicles, power plants, and biomass burning occurs in individual particles, thereby increasing their complexity. Through changes in their optical and hygroscopic properties, internally mixed soot particles have a greater effect on the regional climate than uncoated soot particles. Moreover, soot occurs in more than 60% of all particles in the MC plumes, suggesting its important role in the formation of secondary aerosol particles.

  20. Optical and probe determination of soot concentrations in a model gas turbine combustor

    NASA Technical Reports Server (NTRS)

    Eckerle, W. A.; Rosfjord, T. J.

    1986-01-01

    An experimental program was conducted to track the variation in soot loading in a generic gas turbine combustor. The burner is a 12.7-cm dia cylindrical device consisting of six sheet-metal louvers. Determination of soot loading along the burner length is achieved by measurement at the exit of the combustor and then at upstream stations by sequential removal of liner louvers to shorten burner length. Alteration of the flow field approaching and within the shortened burners is minimized by bypassing flow in order to maintain a constant linear pressure drop. The burner exhaust flow is sampled at the burner centerline to determine soot mass concentration and smoke number. Characteristic particle size and number density, transmissivity of the exhaust flow, and local radiation from luminous soot particles in the exhaust are determined by optical techniques. Four test fuels are burned at three fuel-air ratios to determine fuel chemical property and flow temperature influences. Particulate concentration data indicate a strong oxidation mechanism in the combustor secondary zone, though the oxidation is significantly affected by flow temperature. Soot production is directly related to fuel smoke point.

  1. Development of a dose-controlled multiculture cell exposure chamber for efficient delivery of airborne and engineered nanoparticles

    NASA Astrophysics Data System (ADS)

    Asimakopoulou, Akrivi; Daskalos, Emmanouil; Lewinski, Nastassja; Riediker, Michael; Papaioannou, Eleni; Konstandopoulos, Athanasios G.

    2013-04-01

    In order to study the various health influencing parameters related to engineered nanoparticles as well as to soot emitted by Diesel engines, there is an urgent need for appropriate sampling devices and methods for cell exposure studies that simulate the respiratory system and facilitate associated biological and toxicological tests. The objective of the present work was the further advancement of a Multiculture Exposure Chamber (MEC) into a dose-controlled system for efficient delivery of nanoparticles to cells. It was validated with various types of nanoparticles (Diesel engine soot aggregates, engineered nanoparticles for various applications) and with state-of-the-art nanoparticle measurement instrumentation to assess the local deposition of nanoparticles on the cell cultures. The dose of nanoparticles to which cell cultures are being exposed was evaluated in the normal operation of the in vitro cell culture exposure chamber based on measurements of the size specific nanoparticle collection efficiency of a cell free device. The average efficiency in delivering nanoparticles in the MEC was approximately 82%. The nanoparticle deposition was demonstrated by Transmission Electron Microscopy (TEM). Analysis and design of the MEC employs Computational Fluid Dynamics (CFD) and true to geometry representations of nanoparticles with the aim to assess the uniformity of nanoparticle deposition among the culture wells. Final testing of the dose-controlled cell exposure system was performed by exposing A549 lung cell cultures to fluorescently labeled nanoparticles. Delivery of aerosolized nanoparticles was demonstrated by visualization of the nanoparticle fluorescence in the cell cultures following exposure. Also monitored was the potential of the aerosolized nanoparticles to generate reactive oxygen species (ROS) (e.g. free radicals and peroxides generation), thus expressing the oxidative stress of the cells which can cause extensive cellular damage or damage on DNA.

  2. Sooting Limits Of Microgravity Spherical Diffusion Flames. [conducted in the NASA Glenn 2.2-second drop tower

    NASA Technical Reports Server (NTRS)

    Sunderland, P. B.; Urban, D. L.; Stocker, D. P.; Chao, B.-H.; Axelbaum, Richard L.; Salzman, Jack (Technical Monitor)

    2001-01-01

    Limiting conditions for soot-particle inception were studied in microgravity spherical diffusion flames burning ethylene at atmospheric pressure. Nitrogen was supplied in the fuel and/or oxidizer to obtain the broadest range of stoichiometric mixture fraction. Both normal flames (oxygen in ambience) and inverted flames (fuel in ambience) were considered. Microgravity was obtained in the NASA Glenn 2.2-second drop tower. The flames were observed with a color video camera and sooting conditions were defined as conditions for which yellow emission was present throughout the duration of the drop. Sooting limit results were successfully correlated in terms of adiabatic flame temperature and stoichiometric mixture fraction. Soot free conditions were favored by increased stoichiometric mixture fractions. No statistically significant effect of convection direction on sooting limits was observed. The relationship between adiabatic flame temperature and stoichiometric mixture fraction at the sooting limits was found to be in qualitative agreement with a simple theory based on the assumption that soot inception can occur only where temperature and local C/O ratio exceed threshold values (circa 1250 K and 1, respectively).

  3. Method of moments comparison for soot population modeling in turbulent combustion

    NASA Astrophysics Data System (ADS)

    Chong, Shao Teng; Im, Hong; Raman, Venkat

    2017-11-01

    Representation of soot population is an important component in the efficient computational prediction of particulate emissions. However, there are a number of moments-based techniques with varying numerical complexity. In the past, development of such methods has been principally carried out on canonical laminar and 0-D flows. However, their applications in realistic solvers developed for turbulent combustion may face challenges from turbulence closure to selection of moment sets. In this work, the accuracy and relative computational expense of a few common soot method of moments are tested in canonical turbulent flames for different configurations. Large eddy simulation (LES) will be used as the turbulence modeling framework. In grid-filtered LES, the interaction of numerical and modeling errors is a first-order problem that can undermine the accuracy of soot predictions. In the past, special moments-based methods for solvers that transport high frequency content fluid with ability to reconstruct particle size distribution have been developed. Here, a similar analysis will be carried out for the moment-based soot modeling approaches above. Specifically, realizability of moments methods with nonlinear advection schemes will be discussed.

  4. An analysis of field-aged diesel particulate filter performance: particle emissions before, during, and after regeneration.

    PubMed

    Barone, Teresa L; Storey, John M E; Domingo, Norberto

    2010-08-01

    A field-aged, passive diesel particulate filter (DPF) used in a school bus retrofit program was evaluated for emissions of particle mass and number concentration before, during, and after regeneration. For the particle mass measurements, filter samples were collected for gravimetric analysis with a partial flow sampling system, which sampled proportionally to the exhaust flow. A condensation particle counter and scanning mobility particle sizer measured total number concentration and number-size distributions, respectively. The results of the evaluation show that the number concentration emissions decreased as the DPF became loaded with soot. However, after soot removal by regeneration, the number concentration emissions were approximately 20 times greater, which suggests the importance of the soot layer in helping to trap particles. Contrary to the number concentration results, particle mass emissions decreased from 6 +/- 1 mg/hp-hr before regeneration to 3 +/- 2 mg/hp-hr after regeneration. This indicates that nanoparticles with diameters less than 50 nm may have been emitted after regeneration because these particles contribute little to the total mass. Overall, average particle emission reductions of 95% by mass and 10,000-fold by number concentration after 4 yr of use provided evidence of the durability of a field-aged DPF. In contrast to previous reports for new DPFs in which elevated number concentrations occurred during the first 200 sec of a transient cycle, the number concentration emissions were elevated during the second half of the heavy-duty Federal Test Procedure (FTP) when high speed was sustained. This information is relevant for the analysis of mechanisms by which particles are emitted from field-aged DPFs.

  5. The Atmospheric Effects of Soot Resulting From a Nuclear Conflict

    DTIC Science & Technology

    1985-03-20

    winl break up Into long vertical f-la1ents. This process may significantly change the mean optical properties of the cloud layer .and thus alter the... changes predicted by ICA CC4 foliowing injection of a unifomt soot layer in a 30 . . . . . . . . . . . .. . .t. . . . . 12 4 T~rtu changes predicted...by the EB, followdzx a sprintime (22 Ma•rch) injection of a uniform soot Iin a 300 to 700,i band ....... ............... 14 5 Tmq.r’ature changes

  6. Ship diesel emission aerosols: A comprehensive study on the chemical composition, the physical properties and the molecular biological and toxicological effects on human lung cells of aerosols from a ship diesel engine operated with heavy or light diesel fuel oil

    NASA Astrophysics Data System (ADS)

    Zimmermann, R.; Buters, J.; Öder, S.; Dietmar, G.; Kanashova, T.; Paur, H.; Dilger, M.; Mülhopt, S.; Harndorf, H.; Stengel, B.; Rabe, R.; Hirvonen, M.; Jokiniemi, J.; Hiller, K.; Sapcariu, S.; Berube, K.; Sippula, O.; Streibel, T.; Karg, E.; Schnelle-Kreis, J.; Lintelmann, J.; Sklorz, M.; Arteaga Salas, M.; Orasche, J.; Müller, L.; Reda, A.; Passig, J.; Radischat, C.; Gröger, T.; Weiss, C.

    2013-12-01

    observed acute-toxic effects. The influence of transition metals and alkylated PAH is discussed in this context. Finally the differential biological effects of LFO- and HFO-ship emissions were investigated thoroughly. Here interesting observation were made. The chemical profile of the ship diesel engine operated with HFO and LFO is very different. Although the soot content of LFO exhaust is higher, the HFO-PM is showing considerably higher toxic- and biological-effects in the on-line cell exposure experiments. This higher particle toxicity is associated with larger aromatic structures and transition-metal contend in the PM. In addition to PM also the gas phase of the emission was investigated, e.g. by on-line photo ionization mass spectrometry and off-line techniques. Further results will be dis-cussed in the contribution. The massive differences of LFO and HFO emission are thoroughly discussed with respect to the chemical signature of gas and particulate phase. Furthermore concept and first results on a simulated aging are presented.

  7. Investigation of in-flame soot optical properties in laminar coflow diffusion flames using thermophoretic particle sampling and spectral light extinction

    NASA Astrophysics Data System (ADS)

    Kempema, Nathan J.; Ma, Bin; Long, Marshall B.

    2016-09-01

    Soot optical properties are essential to the noninvasive study of the in-flame evolution of soot particles since they allow quantitative interpretation of optical diagnostics. Such experimental data are critical for comparison to results from computational models and soot sub-models. In this study, the thermophoretic sampling particle diagnostic (TSPD) technique is applied along with data from a previous spectrally resolved line-of-sight light attenuation experiment to determine the soot volume fraction and absorption function. The TSPD technique is applied in a flame stabilized on the Yale burner, and the soot scattering-to-absorption ratio is calculated using the Rayleigh-Debye-Gans theory for fractal aggregates and morphology information from a previous sampling experiment. The soot absorption function is determined as a function of wavelength and found to be in excellent agreement with previous in-flame measurements of the soot absorption function in coflow laminar diffusion flames. Two-dimensional maps of the soot dispersion exponent are calculated and show that the soot absorption function may have a positive or negative exponential wavelength dependence depending on the in-flame location. Finally, the wavelength dependence of the soot absorption function is related to the ratio of soot absorption functions, as would be found using two-excitation-wavelength laser-induced incandescence.

  8. The use of liquid latex for soot removal from fire scenes and attempted fingerprint development with Ninhydrin.

    PubMed

    Clutter, Susan Wright; Bailey, Robert; Everly, Jeff C; Mercer, Karl

    2009-11-01

    Throughout the United States, clearance rates for arson cases remain low due to fire's destructive nature, subsequent suppression, and a misconception by investigators that no forensic evidence remains. Recent research shows that fire scenes can yield fingerprints if soot layers are removed prior to using available fingerprinting processes. An experiment applying liquid latex to sooted surfaces was conducted to assess its potential to remove soot and yield fingerprints after the dried latex was peeled. Latent fingerprints were applied to glass and drywall surfaces, sooted in a controlled burn, and cooled. Liquid latex was sprayed on, dried, and peeled. Results yielded usable prints within the soot prior to removal techniques, but no further fingerprint enhancement was noted with Ninhydrin. Field studies using liquid latex will be continued by the (US) Virginia Fire Marshal Academy but it appears that liquid latex application is a suitable soot removal method for forensic applications.

  9. On transient climate change at the Cretaceous-Paleogene boundary due to atmospheric soot injections.

    PubMed

    Bardeen, Charles G; Garcia, Rolando R; Toon, Owen B; Conley, Andrew J

    2017-09-05

    Climate simulations that consider injection into the atmosphere of 15,000 Tg of soot, the amount estimated to be present at the Cretaceous-Paleogene boundary, produce what might have been one of the largest episodes of transient climate change in Earth history. The observed soot is believed to originate from global wildfires ignited after the impact of a 10-km-diameter asteroid on the Yucatán Peninsula 66 million y ago. Following injection into the atmosphere, the soot is heated by sunlight and lofted to great heights, resulting in a worldwide soot aerosol layer that lasts several years. As a result, little or no sunlight reaches the surface for over a year, such that photosynthesis is impossible and continents and oceans cool by as much as 28 °C and 11 °C, respectively. The absorption of light by the soot heats the upper atmosphere by hundreds of degrees. These high temperatures, together with a massive injection of water, which is a source of odd-hydrogen radicals, destroy the stratospheric ozone layer, such that Earth's surface receives high doses of UV radiation for about a year once the soot clears, five years after the impact. Temperatures remain above freezing in the oceans, coastal areas, and parts of the Tropics, but photosynthesis is severely inhibited for the first 1 y to 2 y, and freezing temperatures persist at middle latitudes for 3 y to 4 y. Refugia from these effects would have been very limited. The transient climate perturbation ends abruptly as the stratosphere cools and becomes supersaturated, causing rapid dehydration that removes all remaining soot via wet deposition.

  10. On transient climate change at the Cretaceous-Paleogene boundary due to atmospheric soot injections

    NASA Astrophysics Data System (ADS)

    Bardeen, Charles G.; Garcia, Rolando R.; Toon, Owen B.; Conley, Andrew J.

    2017-09-01

    Climate simulations that consider injection into the atmosphere of 15,000 Tg of soot, the amount estimated to be present at the Cretaceous-Paleogene boundary, produce what might have been one of the largest episodes of transient climate change in Earth history. The observed soot is believed to originate from global wildfires ignited after the impact of a 10-km-diameter asteroid on the Yucatán Peninsula 66 million y ago. Following injection into the atmosphere, the soot is heated by sunlight and lofted to great heights, resulting in a worldwide soot aerosol layer that lasts several years. As a result, little or no sunlight reaches the surface for over a year, such that photosynthesis is impossible and continents and oceans cool by as much as 28 °C and 11 °C, respectively. The absorption of light by the soot heats the upper atmosphere by hundreds of degrees. These high temperatures, together with a massive injection of water, which is a source of odd-hydrogen radicals, destroy the stratospheric ozone layer, such that Earth’s surface receives high doses of UV radiation for about a year once the soot clears, five years after the impact. Temperatures remain above freezing in the oceans, coastal areas, and parts of the Tropics, but photosynthesis is severely inhibited for the first 1 y to 2 y, and freezing temperatures persist at middle latitudes for 3 y to 4 y. Refugia from these effects would have been very limited. The transient climate perturbation ends abruptly as the stratosphere cools and becomes supersaturated, causing rapid dehydration that removes all remaining soot via wet deposition.

  11. On transient climate change at the Cretaceous−Paleogene boundary due to atmospheric soot injections

    PubMed Central

    Garcia, Rolando R.; Toon, Owen B.; Conley, Andrew J.

    2017-01-01

    Climate simulations that consider injection into the atmosphere of 15,000 Tg of soot, the amount estimated to be present at the Cretaceous−Paleogene boundary, produce what might have been one of the largest episodes of transient climate change in Earth history. The observed soot is believed to originate from global wildfires ignited after the impact of a 10-km-diameter asteroid on the Yucatán Peninsula 66 million y ago. Following injection into the atmosphere, the soot is heated by sunlight and lofted to great heights, resulting in a worldwide soot aerosol layer that lasts several years. As a result, little or no sunlight reaches the surface for over a year, such that photosynthesis is impossible and continents and oceans cool by as much as 28 °C and 11 °C, respectively. The absorption of light by the soot heats the upper atmosphere by hundreds of degrees. These high temperatures, together with a massive injection of water, which is a source of odd-hydrogen radicals, destroy the stratospheric ozone layer, such that Earth’s surface receives high doses of UV radiation for about a year once the soot clears, five years after the impact. Temperatures remain above freezing in the oceans, coastal areas, and parts of the Tropics, but photosynthesis is severely inhibited for the first 1 y to 2 y, and freezing temperatures persist at middle latitudes for 3 y to 4 y. Refugia from these effects would have been very limited. The transient climate perturbation ends abruptly as the stratosphere cools and becomes supersaturated, causing rapid dehydration that removes all remaining soot via wet deposition. PMID:28827324

  12. Minor and Trace Element Chemistry of Urban NS-Soot from the Central Valley of CA, USA

    NASA Astrophysics Data System (ADS)

    Kleich, S. J.; Hooper, R.

    2017-12-01

    During a recent study of metal transport in the Central Valley of California, it was noted that ns-soot (soot) occurred as complex clusters of graphene-like spheres admixed with other aerosols and were usually the dominant component of PM2.5 air particulates. These soot clusters contained a wide variety of metals of environmental concern such as As,Pb,Cr, and Ni. This study reports semi-quantitative results for 20 minor and trace elements (calibrated with Smithsonian microbeam standards) using a 200kV Transmission Electron Microscope, EDS, and SAED. This study also examined the mineralogy and crystallinity of admixed aerosols within composite soot clusters. Samples selected represent three contrasting urban settings in the Central Valley: Woodland, on the western side of the valley (Interstate highway to the east); Stockton, an inland sea-port and land transportation corridor in the center of the valley; and Roseville, a major rail-transport hub to the east. The wet/dry Mediterranean climate of California resulted in pronounced seasonal variations in total metal content. Soot cluster chemistry is highly variable however certain patterns emerged. Soot collected during the wet season is generally more aciniform, less structurally complex, and had lower sulfur (sulfate) concentrations but still had significant levels of transition metals (V,Cr,Mn,Fe,Ni,Zn and Pb) . Dry season soot was predominantly admixed with sulfate aerosols, and enriched in alkalis and alkaline earth metals. Stockton (wet-season) soot had up to 6000ppm of Pb. There is appreciable Pb (210ppm-2600ppm) in 38% of samples from Roseville but no Pb greater than 200ppm in Woodland. The highest overall total metals were found in Roseville soot with appreciable As(670ppm), V(100ppm), Pb(2600ppm), Zn(4000 ppm), Cr(90ppm), and Ni(300ppm). Heavy transport (road/rail/port) correlates with higher metal contents regardless of climate.

  13. Laser Diagnostic Analyses of Sooting Flames.

    DTIC Science & Technology

    1984-11-29

    flame front as expected. However the fuel flame length is considerably shorter than the luminous height, and the flame surface must cross the soot surface...very useful in understanding this behaviour and the fact that the fuel flame length increases only slightly on addition of diluent--while the visible

  14. Soot and Spectral Radiation Modeling in ECN Spray A and in Engines

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Haworth, Daniel C; Ferreyro-Fernandez, Sebastian; Paul, Chandan

    The amount of soot formed in a turbulent combustion system is determined by a complex system of coupled nonlinear chemical and physical processes. Different physical subprocesses can dominate, depending on the hydrodynamic and thermochemical environments. Similarly, the relative importance of reabsorption, spectral radiation properties, and molecular gas radiation versus soot radiation varies with thermochemical conditions, and in ways that are difficult to predict for the highly nonhomogeneous in-cylinder mixtures in engines. Here it is shown that transport and mixing play relatively more important roles as rate-determining processes in soot formation at engine-relevant conditions. It is also shown that molecular gasmore » radiation and spectral radiation properties are important for engine-relevant conditions.« less

  15. Effects of soot by-product from the synthesis of engineered metallofullerene nanomaterials on terrestrial invertebrates.

    PubMed

    Johnson, David R; Boyd, Robert E; Bednar, Anthony J; Weiss, Charles A; Hull, Matt S; Coleman, Jessica G; Kennedy, Alan J; Banks, Cynthia J; Steevens, Jeffery A

    2018-02-23

    The synthesis of carbon-based nanomaterials is often inefficient, generating large amounts of soot with metals as waste by-product. Currently, there are no specific regulations for disposal of engineered nanomaterials or the waste by-products resulting from their synthesis, so it is presumed that by-products are disposed of in the same way as the parent (bulk) materials. We studied the terrestrial toxicity of soot from gadolinium metallofullerene nanomanufacturing on earthworms (Eisenia fetida) and isopods (Porcellio scaber). The metallofullerene soot consisted of carbon particle agglomerates in the nanometer and submicrometer ranges (1-100 and 101-999 nm, respectively), with metals used during nanomanufacturing detectable on the particles. Despite high metal concentrations (>100 000 mg/kg) in the soot, only a relatively small amount of metals leached out of a spiked field soil, suggesting only moderate mobility. Seven- and 14-d exposures in field soil demonstrated that the soot was only toxic to earthworms at high concentrations (>10 000 mg/kg); however, earthworms avoided spiked soils at lower concentrations (as low as 500 mg/kg) and at lower soil pH. The presence of soot in food and soil did not cause isopod avoidance. These data demonstrate that metallofullerene soot from nanomanufacturing may only be toxic to earthworms at high concentrations representative of improper disposal or accidental spills. However, our results indicate that terrestrial invertebrates may avoid soils contaminated with soot at sublethal concentrations. Environ Toxicol Chem 2018;9999:1-12. Published 2018 Wiley Periodicals, Inc. on behalf of SETAC. This article is a US government work, and as such, is in the public domain in the United States of America. Published 2018 Wiley Periodicals, Inc. on behalf of SETAC. This article is a US government work, and as such, is in the public domain in the United States of America.

  16. Diesel oil

    MedlinePlus

    ... oil is a heavy oil used in diesel engines. Diesel oil poisoning occurs when someone swallows diesel ... people trying to suck (siphon) gas from an automobile tank using their mouth and a garden hose ( ...

  17. Effect of Coatings on the Uptake Rate and HONO Yield in Heterogeneous Reaction of Soot with NO2

    NASA Astrophysics Data System (ADS)

    Cruz-Quiñones, M.; Khalizov, A. F.; Zhang, R.

    2009-12-01

    Heterogeneous reaction of nitrogen dioxide on carbon soot aerosols has been suggested as a possible source of nighttime nitrous acid (HONO) in atmosphere boundary layer. Available laboratory data show significant variability in the measured reaction probabilities and HONO yields, making it difficult to asses the atmospheric significance of this process. Moreover, little is known of how aging of soot aerosol through internal mixing with other atmospheric trace constituents will affect the heterogeneous reactivity and HONO production. In this work, the heterogeneous reaction of NO2 on fresh and aged soot films leading to HONO formation was studied through a series of kinetic uptake experiments and HONO yield measurements. Soot samples were prepared by incomplete combustion of propane and kerosene fuels under lean and rich flame conditions. Experiments were performed in a low-pressure, fast-flow reactor coupled to a chemical ionization mass spectrometer (CIMS), using atmospheric-level NO2 concentrations. Heterogeneous uptake coefficients, γ(geom) and γ(BET), were calculated using geometric and internal BET soot surface areas, respectively. The uptake coefficient and the HONO yield depend on the type of fuel and combustion regime and are the highest for soot samples prepared using rich kerosene flame. Although, the internal surface area of soot measured by BET method is a factor of 50 to 500 larger than the geometric surface area, only the top soot layers are involved in heterogeneous reaction with NO2 as follows from the observed weak dependence of γ(geom) and decrease in γ(BET) with increasing sample mass. Heating the soot samples before exposure to NO2 increases the BET surface area, the HONO yield, and the NO2 uptake coefficient due to the removal of the organic fraction from the soot backbone that unblocks active sites and makes them accessible for physical adsorption and chemical reactions. Our results support the oxidation-reduction mechanism involving

  18. Performance of biomorphic Silicon Carbide as particulate filter in diesel boilers.

    PubMed

    Orihuela, M Pilar; Gómez-Martín, Aurora; Becerra, José A; Chacartegui, Ricardo; Ramírez-Rico, Joaquín

    2017-12-01

    Biomorphic Silicon Carbide (bioSiC) is a novel porous ceramic material with excellent mechanical and thermal properties. Previous studies have demonstrated that it may be a good candidate for its use as particle filter media of exhaust gases at medium or high temperature. In order to determine the filtration efficiency of biomorphic Silicon Carbide, and its adequacy as substrate for diesel particulate filters, different bioSiC-samples have been tested in the flue gases of a diesel boiler. For this purpose, an experimental facility to extract a fraction of the boiler exhaust flow and filter it under controlled conditions has been designed and built. Several filter samples with different microstructures, obtained from different precursors, have been tested in this bench. The experimental campaign was focused on the measurement of the number and size of particles before and after placing the samples. Results show that the initial efficiency of filters made from natural precursors is severely determined by the cutting direction and associated microstructure. In biomorphic Silicon Carbide derived from radially cut wood, the initial efficiency of the filter is higher than 95%. Nevertheless, when the cut of the wood is axial, the efficiency depends on the pore size and the permeability, reaching in some cases values in the range 70-90%. In this case, the presence of macropores in some of the samples reduces their efficiency as particle traps. In continuous operation, the accumulation of particles within the porous media leads to the formation of a soot cake, which improves the efficiency except in the case when extra-large pores exist. For all the samples, after a few operation cycles, capture efficiency was higher than 95%. These experimental results show the potential for developing filters for diesel boilers based on biomorphic Silicon Carbide. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Validation of an LES Model for Soot Evolution against DNS Data in Turbulent Jet Flames

    NASA Astrophysics Data System (ADS)

    Mueller, Michael

    2012-11-01

    An integrated modeling approach for soot evolution in turbulent reacting flows is validated against three-dimensional Direct Numerical Simulation (DNS) data in a set of n-heptane nonpremixed temporal jet flames. As in the DNS study, the evolution of the soot population is described statistically with the Hybrid Method of Moments (HMOM). The oxidation of the fuel and formation of soot precursors are described with the Radiation Flamelet/Progress Variable (RFPV) model that includes an additional transport equation for Polycyclic Aromatic Hydrocarbons (PAH) to account for the slow chemistry governing these species. In addition, the small-scale interactions between soot, chemistry, and turbulence are described with a presumed subfilter PDF approach that accounts for the very large spatial intermittency characterizing soot in turbulent reacting flows. The DNS dataset includes flames at three different Damköhler numbers to study the influence of global mixing rates on the evolution of PAH and soot. In this work, the ability of the model to capture these trends quantitatively as Damköhler number varies is investigated. In order to reliably assess the LES approach, the LES is initialized from the filtered DNS data after an initial transitional period in an effort to minimize the hydrodynamic differences between the DNS and the LES.

  20. Effect of hydrogen addition on soot formation in an ethylene/air premixed flame

    NASA Astrophysics Data System (ADS)

    De Iuliis, S.; Maffi, S.; Migliorini, F.; Cignoli, F.; Zizak, G.

    2012-03-01

    The effect of hydrogen addition to fuel in soot formation and growth mechanisms is investigated in a rich ethylene/air premixed flame. To this purpose, three-angle scattering and extinction measurements are carried out in flames with different hydrogen contents. By applying the Rayleigh-Debye-Gans theory and the fractal-like description, soot concentration and morphology, with the evaluation of radius of gyration, volume-mean diameter and primary particle diameter are retrieved. To derive fractal parameters such as fractal dimension and fractal prefactor to be used for optical measurements, sampling technique and TEM analysis are performed. In addition, data concerning soot morphology obtained from TEM analysis are compared with the optical results. A good agreement in the value of the primary particle diameter between optical and ex-situ measurements is found. Significant effects of hydrogen addition are detected and presented in this work. In particular, hydrogen addition to fuel is responsible for a reduction in soot concentration, radius of gyration and primary particle diameter.

  1. Analysis of turbulence and surface growth models on the estimation of soot level in ethylene non-premixed flames

    NASA Astrophysics Data System (ADS)

    Yunardi, Y.; Munawar, Edi; Rinaldi, Wahyu; Razali, Asbar; Iskandar, Elwina; Fairweather, M.

    2018-02-01

    Soot prediction in a combustion system has become a subject of attention, as many factors influence its accuracy. An accurate temperature prediction will likely yield better soot predictions, since the inception, growth and destruction of the soot are affected by the temperature. This paper reported the study on the influences of turbulence closure and surface growth models on the prediction of soot levels in turbulent flames. The results demonstrated that a substantial distinction was observed in terms of temperature predictions derived using the k-ɛ and the Reynolds stress models, for the two ethylene flames studied here amongst the four types of surface growth rate model investigated, the assumption of the soot surface growth rate proportional to the particle number density, but independent on the surface area of soot particles, f ( A s ) = ρ N s , yields in closest agreement with the radial data. Without any adjustment to the constants in the surface growth term, other approaches where the surface growth directly proportional to the surface area and square root of surface area, f ( A s ) = A s and f ( A s ) = √ A s , result in an under- prediction of soot volume fraction. These results suggest that predictions of soot volume fraction are sensitive to the modelling of surface growth.

  2. Uptake of HNO3 on aviation kerosene and aircraft engine soot: influences of H2O or/and H2SO4.

    PubMed

    Loukhovitskaya, Ekaterina E; Talukdar, Ranajit K; Ravishankara, A R

    2013-06-13

    The uptake of HNO3 on aviation kerosene soot (TC-1 soot) was studied in the absence and presence of water vapor at 295 and 243 K. The influence of H2SO4 coating of the TC-1 soot surface on HNO3 uptake was also investigated. Only reversible uptake of HNO3 was observed. HONO and NO2, potential products of reactive uptake of HNO3, were not observed under any conditions studied here. The uptake of nitric acid increased slightly with relative humidity (RH). Coating of the TC-1 soot surface with sulfuric acid decreased the uptake of HNO3 and did not lead to displacement of H2SO4 from the soot surface. A limited set of measurements was carried out on soot generated by aircraft engine combustor (E-soot) with results similar to those on TC-1 soot. The influence of water on HNO3 uptake on E-soot appeared to be more pronounced than on TC-1 soot. Our results suggest that HNO3 loss in the upper troposphere due to soot is not significant except perhaps in aircraft exhaust plumes. Our results also suggest that HNO3 is not converted to either NO2 or HONO upon its uptake on soot in the atmosphere.

  3. Grand canonical Monte Carlo simulation of the adsorption isotherms of water molecules on model soot particles

    NASA Astrophysics Data System (ADS)

    Moulin, F.; Picaud, S.; Hoang, P. N. M.; Jedlovszky, P.

    2007-10-01

    The grand canonical Monte Carlo method is used to simulate the adsorption isotherms of water molecules on different types of model soot particles. The soot particles are modeled by graphite-type layers arranged in an onionlike structure that contains randomly distributed hydrophilic sites, such as OH and COOH groups. The calculated water adsorption isotherm at 298K exhibits different characteristic shapes depending both on the type and the location of the hydrophilic sites and also on the size of the pores inside the soot particle. The different shapes of the adsorption isotherms result from different ways of water aggregation in or/and around the soot particle. The present results show the very weak influence of the OH sites on the water adsorption process when compared to the COOH sites. The results of these simulations can help in interpreting the experimental isotherms of water adsorbed on aircraft soot.

  4. Temperature, Oxygen, and Soot-Volume-Fraction Measurements in a Turbulent C 2H 4-Fueled Jet Flame

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kearney, Sean P.; Guildenbecher, Daniel Robert; Winters, Caroline

    2015-09-01

    We present a detailed set of measurements from a piloted, sooting, turbulent C 2 H 4 - fueled diffusion flame. Hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (CARS) is used to monitor temperature and oxygen, while laser-induced incandescence (LII) is applied for imaging of the soot volume fraction in the challenging jet-flame environment at Reynolds number, Re = 20,000. Single-laser shot results are used to map the mean and rms statistics, as well as probability densities. LII data from the soot-growth region of the flame are used to benchmark the soot source term for one-dimensional turbulence (ODT) modeling of this turbulentmore » flame. The ODT code is then used to predict temperature and oxygen fluctuations higher in the soot oxidation region higher in the flame.« less

  5. Morphological study of fluorescent carbon Nanoparticles (F-CNPs) from ground coffee waste soot oxidation by diluted acid

    NASA Astrophysics Data System (ADS)

    Gea, S.; Tjandra, S.; Joshua, J.; Wirjosentono, B.

    2018-02-01

    Coffee ground waste utilization for fluorescent carbon nanoparticles (F-CNPs) through soot oxidation with diluted HNO3 has been conducted. Soot was obtained through three different treatments to coffee ground waste; which was burned in furnaceat 550°C and 650°C and directly burned in a heat-proofcontainer. Then they were analyzed morphologically with Scanning Electron Microscope (SEM) instrument. Soot from direct burning indicated the optimum result where it has denser pores compared to other two soots. Soot obtained from direct burning was refluxed in diluted HNO3 for 12 hours to perform the oxidation. Yellowish brown supernatant was later observed which lead to green fluorescent under the UV light. F-CNPs characterization was done in Transmission Electron Microscopy, which showed that 7.4-23.4 nm of particle size were distributed.

  6. Significant Climate Changes Caused by Soot Emitted From Rockets in the Stratosphere

    NASA Astrophysics Data System (ADS)

    Mills, M. J.; Ross, M.; Toohey, D. W.

    2010-12-01

    A new type of hydrocarbon rocket engine with a larger soot emission index than current kerosene rockets is expected to power a fleet of suborbital rockets for commercial and scientific purposes in coming decades. At projected launch rates, emissions from these rockets will create a persistent soot layer in the northern middle stratosphere that would disproportionally affect the Earth’s atmosphere and cryosphere. A global climate model predicts that thermal forcing in the rocket soot layer will cause significant changes in the global atmospheric circulation and distributions of ozone and temperature. Tropical ozone columns decline as much as 1%, while polar ozone columns increase by up to 6%. Polar surface temperatures rise one Kelvin regionally and polar summer sea ice fractions shrink between 5 - 15%. After 20 years of suborbital rocket fleet operation, globally averaged radiative forcing (RF) from rocket soot exceeds the RF from rocket CO_{2} by six orders of magnitude, but remains small, comparable to the global RF from aviation. The response of the climate system is surprising given the small forcing, and should be investigated further with different climate models.

  7. Efficient low-temperature soot combustion by bimetallic Ag-Cu/SBA-15 catalysts.

    PubMed

    Wen, Zhaojun; Duan, Xinping; Hu, Menglin; Cao, Yanning; Ye, Linmin; Jiang, Lilong; Yuan, Youzhu

    2018-02-01

    In this study, the effects of copper (Cu) additive on the catalytic performance of Ag/SBA-15 in complete soot combustion were investigated. The soot combustion performance of bimetallic Ag-Cu/SBA-15 catalysts was higher than that of monometallic Ag and Cu catalysts. The optimum catalytic performance was acquired with the 5Ag 1 -Cu 0.1 /SBA-15 catalyst, on which the soot combustion starts at T ig =225°C with a T 50 =285°C. The temperature for 50% of soot combustion was lower than that of conventional Ag-based catalysts to more than 50°C (Aneggi et al., 2009). Physicochemical characterizations of the catalysts indicated that addition of Cu into Ag could form smaller bimetallic Ag-Cu nanolloy particles, downsizing the mean particle size from 3.7nm in monometallic catalyst to 2.6nm in bimetallic Ag-Cu catalyst. Further experiments revealed that Ag and Cu species elicited synergistic effects, subsequently increasing the content of surface active oxygen species. As a result, the structure modifications of Ag by the addition of Cu strongly intensified the catalytic performance. Copyright © 2017. Published by Elsevier B.V.

  8. Climate Effects and Efficacy of Dust and Soot in Snow

    NASA Astrophysics Data System (ADS)

    Zender, C. S.; Flanner, M. G.; Randerson, J. T.; Mahowald, N. M.; Rasch, P. J.; Yoshioka, M.; Painter, T.

    2006-12-01

    Dust and industrial and biomass burning emissions from low and mid-latitudes dominate the absorbing impurities trapped in snow at mid- and high-latitudes. We study the effects of dust and smoke on global and regional climate using a general circulation model driven by observed and predicted aerosol emissions determined from satellite and in situ observations. The model has sophisticated treatments of aerosol and snowpack radiative and thermodynamic processes that compare well with observations of snow albedo evolution and impurity concentration. This presentation focuses on the individual and combined contributions of present day dust and soot to snow-albedo forcing and on the global temperature and snowpack responses. Results are emphasized near India and East Asia, where the anthropogenic aerosol forcing of surface albedo and hydrology is greatest. We find that dust and black carbon (BC) aerosols have climate change efficacies (surface temperature change per unit forcing) about 3--4 times greater than CO2, making them the most efficacious forcing agents known. We estimate present day dust and soot snowpack-forcing of ~ 0.050 W m-2 warms global climate by ~ 0.16 °K. Anthropogenic soot from fossil fuel sources causes more than 50% of this warming, and biomass burning can account for up to 30% in strong tropical or boreal burn years. The greatest forcings occur in the Tarim/Mongol region (due to dust), northeastern China (due to soot), and the Tibetan Plateau (both). Dirty springtime snow in these regions can darken albedo by more than 0.1 and increase surface absorption by more than 20 W m-2. These results have implications for the strength of the Asian Monsoon, which is negatively correlated with antecedent snow cover in non-ENSO years. Dust and soot have such strong efficacies because they increase spring melt rates thus reduce summer snow cover. In some regions and seasons, dirty snow reduces snowpack depth and cover by 50%, triggering strong snow and sea

  9. Mixing state of regionally transported soot particles and the coating effect on their size and shape at a mountain site in Japan

    NASA Astrophysics Data System (ADS)

    Adachi, Kouji; Zaizen, Yuji; Kajino, Mizuo; Igarashi, Yasuhito

    2014-05-01

    Soot particles influence the global climate through interactions with sunlight. A coating on soot particles increases their light absorption by increasing their absorption cross section and cloud condensation nuclei activity when mixed with other hygroscopic aerosol components. Therefore, it is important to understand how soot internally mixes with other materials to accurately simulate its effects in climate models. In this study, we used a transmission electron microscope (TEM) with an auto particle analysis system, which enables more particles to be analyzed than a conventional TEM. Using the TEM, soot particle size and shape (shape factor) were determined with and without coating from samples collected at a remote mountain site in Japan. The results indicate that ~10% of aerosol particles between 60 and 350 nm in aerodynamic diameters contain or consist of soot particles and ~75% of soot particles were internally mixed with nonvolatile ammonium sulfate or other materials. In contrast to an assumption that coatings change soot shape, both internally and externally mixed soot particles had similar shape and size distributions. Larger aerosol particles had higher soot mixing ratios, i.e., more than 40% of aerosol particles with diameters >1 µm had soot inclusions, whereas <20% of aerosol particles with diameters <1 µm included soot. Our results suggest that climate models may use the same size distributions and shapes for both internally and externally mixed soot; however, changing the soot mixing ratios in the different aerosol size bins is necessary.

  10. The effect of oxygen enrichment on soot formation and thermal radiation in turbulent, non-premixed methane flames

    DOE PAGES

    Shaddix, Christopher R.; Williams, Timothy C.

    2016-07-12

    Non-premixed oxy-fuel combustion of natural gas is used in industrial applications where high-intensity heat is required, such as glass manufacturing and metal forging and shaping. In these applications, the high flame temperatures achieved by oxy-fuel combustion increase radiative heat transfer to the surfaces of interest and soot formation within the flame is desired for further augmentation of radiation. However, the high cost of cryogenic air separation has limited the penetration of oxy-fuel combustion technologies. New approaches to air separation are being developed that may reduce oxygen production costs, but only for intermediate levels of oxygen enrichment of air. To determinemore » the influence of oxygen enrichment on soot formation and radiation, we developed a non-premixed coannular burner in which oxygen concentrations and oxidizer flow rates can be independently varied, to distinguish the effects of turbulent mixing intensity from oxygen enrichment on soot formation and flame radiation. Local radiation intensities, soot concentrations, and soot temperatures have been measured using a thin-film thermopile, planar laser-induced incandescence (LII), and two-color imaging pyrometry, respectively. The measurements show that soot formation increases as the oxygen concentration decreases from 100% to 50%, helping to moderate a decrease in overall flame radiation. An increase in turbulence intensity has a marked effect on flame height, soot formation and thermal radiation, leading to decreases in all of these. The soot temperature decreases with a decrease in the oxygen concentration and increases with an increase in turbulent mixing intensity. Altogether, the results suggest that properly designed oxygen-enriched burners that enhance soot formation for intermediate levels of oxygen purity may be able to achieve thermal radiation intensities as high as 85% of traditional oxy-fuel burners utilizing high-purity oxygen.« less

  11. The effect of oxygen enrichment on soot formation and thermal radiation in turbulent, non-premixed methane flames

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Shaddix, Christopher R.; Williams, Timothy C.

    Non-premixed oxy-fuel combustion of natural gas is used in industrial applications where high-intensity heat is required, such as glass manufacturing and metal forging and shaping. In these applications, the high flame temperatures achieved by oxy-fuel combustion increase radiative heat transfer to the surfaces of interest and soot formation within the flame is desired for further augmentation of radiation. However, the high cost of cryogenic air separation has limited the penetration of oxy-fuel combustion technologies. New approaches to air separation are being developed that may reduce oxygen production costs, but only for intermediate levels of oxygen enrichment of air. To determinemore » the influence of oxygen enrichment on soot formation and radiation, we developed a non-premixed coannular burner in which oxygen concentrations and oxidizer flow rates can be independently varied, to distinguish the effects of turbulent mixing intensity from oxygen enrichment on soot formation and flame radiation. Local radiation intensities, soot concentrations, and soot temperatures have been measured using a thin-film thermopile, planar laser-induced incandescence (LII), and two-color imaging pyrometry, respectively. The measurements show that soot formation increases as the oxygen concentration decreases from 100% to 50%, helping to moderate a decrease in overall flame radiation. An increase in turbulence intensity has a marked effect on flame height, soot formation and thermal radiation, leading to decreases in all of these. The soot temperature decreases with a decrease in the oxygen concentration and increases with an increase in turbulent mixing intensity. Altogether, the results suggest that properly designed oxygen-enriched burners that enhance soot formation for intermediate levels of oxygen purity may be able to achieve thermal radiation intensities as high as 85% of traditional oxy-fuel burners utilizing high-purity oxygen.« less

  12. Soot Precursor Material: Spatial Location via Simultaneous LIF-LII Imaging and Characterization via TEM

    NASA Technical Reports Server (NTRS)

    VanderWal, Randall L.

    1996-01-01

    The chemical and physical transformation between gaseous fuel pyrolysis products and solid carbonaceous soot represents a critical step in soot formation. In this paper, simultaneous two-dimensional LIF-LII (laser-induced fluorescence - laser-induced incandescence) images identify the spatial location where the earliest identifiable chemical and physical transformation of material towards solid carbonaceous soot occurs along the axial streamline in a normal diffusion flame. The identification of the individual LIF and LII signals is achieved by examining both the excitation wavelength dependence and characteristic temporal decay of each signal. Spatially precise thermophoretic sampling measurements are guided by the LIF-LII images with characterization of the sampled material accomplished via both bright and dark field TEM. Both bright and dark field TEM measurements support the observed changes in photophysical properties which account for conversion of fluorescence to incandescence as fuel pyrolysis products evolve towards solid carbonaceous soot.

  13. Measurements and Modeling of Soot Formation and Radiation in Microgravity Jet Diffusion Flames. Volume 4

    NASA Technical Reports Server (NTRS)

    Ku, Jerry C.; Tong, Li; Greenberg, Paul S.

    1996-01-01

    This is a computational and experimental study for soot formation and radiative heat transfer in jet diffusion flames under normal gravity (1-g) and microgravity (0-g) conditions. Instantaneous soot volume fraction maps are measured using a full-field imaging absorption technique developed by the authors. A compact, self-contained drop rig is used for microgravity experiments in the 2.2-second drop tower facility at NASA Lewis Research Center. On modeling, we have coupled flame structure and soot formation models with detailed radiation transfer calculations. Favre-averaged boundary layer equations with a k-e-g turbulence model are used to predict the flow field, and a conserved scalar approach with an assumed Beta-pdf are used to predict gaseous species mole fraction. Scalar transport equations are used to describe soot volume fraction and number density distributions, with formation and oxidation terms modeled by one-step rate equations and thermophoretic effects included. An energy equation is included to couple flame structure and radiation analyses through iterations, neglecting turbulence-radiation interactions. The YIX solution for a finite cylindrical enclosure is used for radiative heat transfer calculations. The spectral absorption coefficient for soot aggregates is calculated from the Rayleigh solution using complex refractive index data from a Drude- Lorentz model. The exponential-wide-band model is used to calculate the spectral absorption coefficient for H20 and C02. It is shown that when compared to results from true spectral integration, the Rosseland mean absorption coefficient can provide reasonably accurate predictions for the type of flames studied. The soot formation model proposed by Moss, Syed, and Stewart seems to produce better fits to experimental data and more physically sound than the simpler model by Khan et al. Predicted soot volume fraction and temperature results agree well with published data for a normal gravity co-flow laminar

  14. Heavy-Duty Low-Temperature and Diesel Combustion & Heavy-Duty Combustion Modeling

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Musculus, Mark P.

    Regulatory drivers and market demands for lower pollutant emissions, lower carbon dioxide emissions, and lower fuel consumption motivate the development of clean and fuel-efficient engine operating strategies. Most current production engines use a combination of both in-cylinder and exhaust emissions-control strategies to achieve these goals. The emissions and efficiency performance of in-cylinder strategies depend strongly on flow and mixing processes associated with fuel injection. Various diesel engine manufacturers have adopted close-coupled post-injection combustion strategies to both reduce pollutant emissions and to increase engine efficiency for heavy-duty applications, as well as for light- and medium-duty applications. Close-coupled post-injections are typically shortmore » injections that follow a larger main injection in the same cycle after a short dwell, such that the energy conversion efficiency of the post-injection is typical of diesel combustion. Of the various post-injection schedules that have been reported in the literature, effects on exhaust soot vary by roughly an order of magnitude in either direction of increasing or decreasing emissions relative to single injections (O’Connor et al., 2015). While several hypotheses have been offered in the literature to help explain these observations, no clear consensus has been established. For new engines to take full advantage of the benefits that post-injections can offer, the in-cylinder mechanisms that affect emissions and efficiency must be identified and described to provide guidance for engine design.« less

  15. Comprehensive Characterization Of Ultrafine Particulate Emission From 2007 Diesel Engines: PM Size Distribution, Loading And Indidividual Particle Size And Composition.

    NASA Astrophysics Data System (ADS)

    Zelenyuk, A.; Cuadra-Rodriguez, L. A.; Imre, D.; Shimpi, S.; Warey, A.

    2006-12-01

    The strong absorption of solar radiation by black carbon (BC) impacts the atmospheric radiative balance in a complex and significant manner. One of the most important sources of BC is vehicular emissions, of which diesel represents a significant fraction. To address this issue the EPA has issues new stringent regulations that will be in effect in 2007, limiting the amount of particulate mass that can be emitted by diesel engines. The new engines are equipped with aftertreatments that reduce PM emissions to the point, where filter measurements are subject to significant artifacts and characterization by other techniques presents new challenges. We will present the results of the multidisciplinary study conducted at the Cummins Technical Center in which a suite of instruments was deployed to yield comprehensive, temporally resolved information on the diesel exhaust particle loadings and properties in real-time: Particle size distributions were measured by Engine Exhaust Particle Sizer (EEPS) and Scanning Mobility Particle Sizer (SMPS). Total particle diameter concentration was obtained using Electrical Aerosol Detector (EAD). Laser Induced Incandescence and photoacoustic techniques were used to monitor the PM soot content. Single Particle Laser Ablation Time-of- flight Mass Spectrometer (SPLAT) provided the aerodynamic diameter and chemical composition of individual diesel exhaust particles. Measurements were conducted on a number of heavy duty diesel engines operated under variety of operating conditions, including FTP transient cycles, ramped-modal cycles and steady states runs. We have also characterized PM emissions during diesel particulate filter regeneration cycles. We will present a comparison of PM characteristics observed during identical cycles, but with and without the use of aftertreatment. A total of approximately 100,000 individual particles were sized and their composition characterized by SPLAT. The aerodynamic size distributions of the characterized

  16. Adhesion of Mineral and Soot Aerosols can Strongly Affect their Scattering and Absorption Properties

    NASA Technical Reports Server (NTRS)

    Mishchenko, Michael I.; Dlugach, Jana M.

    2012-01-01

    We use the numerically exact superposition T-matrix method to compute the optical cross sections and the Stokes scattering matrix for polydisperse mineral aerosols (modeled as homogeneous spheres) covered with a large number of much smaller soot particles. These results are compared with the Lorenz-Mie results for a uniform external mixture of mineral and soot aerosols. We show that the effect of soot particles adhering to large mineral particles can be to change the extinction and scattering cross sections and the asymmetry parameter quite substantially. The effect on the phase function and degree of linear polarization can be equally significant.

  17. [Particle emission characteristics of diesel bus fueled with bio-diesel].

    PubMed

    Lou, Di-Ming; Chen, Feng; Hu, Zhi-Yuan; Tan, Pi-Qiang; Hu, Wei

    2013-10-01

    With the use of the Engine Exhaust Particle Sizer (EEPS), a study on the characteristics of particle emissions was carried out on a China-IV diesel bus fueled with blends of 5% , 10% , 20% , 50% bio-diesel transformed from restaurant waste oil and China-IV diesel (marked separately by BD5, BD10, BD20, BD50), pure bio-diesel (BD100) and pure diesel (BD0). The results indicated that particulate number (PN) and mass (PM) emissions of bio-diesel blends increased with the increase in bus speed and acceleration; with increasing bio-diesel content, particulate emissions displayed a relevant declining trend. In different speed ranges, the size distribution of particulate number emissions (PNSD) was bimodal; in different acceleration ranges, PNSD showed a gradual transition from bimodal shape to unimodal when bus operation was switched from decelerating to accelerating status. Bio-diesel blends with higher mixture ratios showed significant reduction in PN emissions for accumulated modes, and the particulate number emission peaks moved towards smaller sizes; but little change was obtained in PN emissions for nuclei modes; reduction also occurred in particle geometric diameter (Dg).

  18. Effects of Structure and Hydrodynamics on the Sooting Behavior of Spherical Microgravity Diffusion Flames

    NASA Technical Reports Server (NTRS)

    Sunderland, P. B.; Axelbaum, Richard L.; Urban, D. L.

    2000-01-01

    We have examined the sooting behavior of spherical microgravity diffusion flames burning ethylene at atmospheric pressure in the NASA Glenn 2.2-second drop tower. In a novel application of microgravity, spherical flames allowed convection across the flame to be either from fuel to oxidizer or from oxidizer to fuel. Thus, microgravity flames are uniquely capable of allowing independent variation of convection direction across the flame and stoichiometric mixture fraction, Z(sub st). This allowed us to determine the dominant mechanism responsible for the phenomenon of permanently-blue diffusion flames -- flames that remain blue as strain rate approaches zero. Stoichiometric mixture fraction was varied by changing inert concentrations such that adiabatic flame temperature did not change. At low and high Z(sub st) nitrogen was supplied with the oxidizer and the fuel, respectively. For the present flames, structure (Z(sub st)) was found to have a profound effect on soot production. Soot-free conditions were observed at high Z(sub st) (Z(sub st) = 0.78) and sooting conditions were observed at low Z(sub st) (Z(sub st) = 0.064) regardless of the direction of convection. Convection direction was found to have a lesser impact on soot inception, with formation being suppressed when convection at the flame sheet was directed towards the oxidizer.

  19. Effects of soot absorption coefficient-Planck function correlation on radiative heat transfer in oxygen-enriched propane turbulent diffusion flame

    NASA Astrophysics Data System (ADS)

    Consalvi, J. L.; Nmira, F.

    2016-03-01

    The main objective of this article is to quantify the influence of the soot absorption coefficient-Planck function correlation on radiative loss and flame structure in an oxygen-enhanced propane turbulent diffusion flame. Calculations were run with and without accounting for this correlation by using a standard k-ε model and the steady laminar flamelet model (SLF) coupled to a joint Probability Density Function (PDF) of mixture fraction, enthalpy defect, scalar dissipation rate, and soot quantities. The PDF transport equation is solved by using a Stochastic Eulerian Field (SEF) method. The modeling of soot production is carried out by using a flamelet-based semi-empirical acetylene/benzene soot model. Radiative heat transfer is modeled by using a wide band correlated-k model and turbulent radiation interactions (TRI) are accounted for by using the Optically-Thin Fluctuation Approximation (OTFA). Predicted soot volume fraction, radiant wall heat flux distribution and radiant fraction are in good agreement with the available experimental data. Model results show that soot absorption coefficient and Planck function are negatively correlated in the region of intense soot emission. Neglecting this correlation is found to increase significantly the radiative loss leading to a substantial impact on flame structure in terms of mean and rms values of temperature. In addition mean and rms values of soot volume fraction are found to be less sensitive to the correlation than temperature since soot formation occurs mainly in a region where its influence is low.

  20. Improvement of engine emissions with conventional diesel fuel and diesel-biodiesel blends.

    PubMed

    Nabi, Md Nurun; Akhter, Md Shamim; Zaglul Shahadat, Mhia Md

    2006-02-01

    In this report combustion and exhaust emissions with neat diesel fuel and diesel-biodiesel blends have been investigated. In the investigation, firstly biodiesel from non-edible neem oil has been made by esterification. Biodiesel fuel (BDF) is chemically known as mono-alkyl fatty acid ester. It is renewable in nature and is derived from plant oils including vegetable oils. BDF is non-toxic, biodegradable, recycled resource and essentially free from sulfur and carcinogenic benzene. In the second phase of this investigation, experiment has been conducted with neat diesel fuel and diesel-biodiesel blends in a four stroke naturally aspirated (NA) direct injection (DI) diesel engine. Compared with conventional diesel fuel, diesel-biodiesel blends showed lower carbon monoxide (CO), and smoke emissions but higher oxides of nitrogen (NOx) emission. However, compared with the diesel fuel, NOx emission with diesel-biodiesel blends was slightly reduced when EGR was applied.

  1. Comparative Soot Diagnostics: Preliminary Results

    NASA Technical Reports Server (NTRS)

    Urban, David L.; Griffin, DeVon W.; Gard, Melissa Y.

    1997-01-01

    The motivation for the Comparative Soot Diagnostics (CSD) experiment lies in the broad practical importance of understanding combustion generated particulate. Depending upon the circumstances, particulate matter can affect the durability and performance of combustion equipment, can be a pollutant, can be used to detect fires and, in the form of soot, can be the dominant source of radiant energy from flames. The nonbuoyant structure of most flames of practical interest makes understanding of soot processes in low gravity flames important to our ability to predict fire behavior on earth. These studies also have direct applications to fire safety in human-crew spacecraft, since smoke is the indicator used for automated detection in current spacecraft. In the earliest missions (Mercury, Gemini and Apollo), the crew quarters were so cramped that it was considered reasonable that the astronauts would rapidly detect any fire. The Skylab module, however, included approximately 20 UV-sensing fire detectors. The Space Shuttle has 9 particle-ionization smoke detectors in the mid-deck and flight deck and Spacelab has six additional particle-ionization smoke detectors. The designated detectors for the ISS are laser-diode, forward-scattering, smoke or particulate detectors. Current plans for the ISS call for two detectors in the open area of the module, and detectors in racks that have both cooling air flow and electrical power. Due to the complete absence of data concerning the nature of particulate and radiant emission from incipient and fully developed low-g fires, all three of these detector systems were designed based upon l-g test data and experience. As planned mission durations and complexity increase and the volume of spacecraft increases, the need for and importance of effective, crew-independent, fire detection grows significantly. To provide this level of protection, more knowledge is needed concerning low-gravity fire phenomena and, in particular, how they might be

  2. Soot volume fraction fields in unsteady axis-symmetric flames by continuous laser extinction technique.

    PubMed

    Kashif, Muhammad; Bonnety, Jérôme; Guibert, Philippe; Morin, Céline; Legros, Guillaume

    2012-12-17

    A Laser Extinction Method has been set up to provide two-dimensional soot volume fraction field time history at a tunable frequency up to 70 Hz inside an axis-symmetric diffusion flame experiencing slow unsteady phenomena preserving the symmetry. The use of a continuous wave laser as the light source enables this repetition rate, which is an incremental advance in the laser extinction technique. The technique is shown to allow a fine description of the soot volume fraction field in a flickering flame exhibiting a 12.6 Hz flickering phenomenon. Within this range of repetition rate, the technique and its subsequent post-processing require neither any method for time-domain reconstruction nor any correction for energy intrusion. Possibly complemented by such a reconstruction method, the technique should support further soot volume fraction database in oscillating flames that exhibit characteristic times relevant to the current efforts in the validation of soot processes modeling.

  3. Ordered micro/macro porous K-OMS-2/SiO2 nanocatalysts: Facile synthesis, low cost and high catalytic activity for diesel soot combustion

    PubMed Central

    Yu, Xuehua; Zhao, Zhen; Wei, Yuechang; Liu, Jian

    2017-01-01

    A series of novel oxide catalysts, which contain three-dimensionally ordered macroporous (3DOM) and microporous structure, were firstly designed and successfully synthesized by simple method. In the as-prepared catalysts, 3DOM SiO2 is used as support and microporous K-OMS-2 oxide nanoparticles are supported on the wall of SiO2. 3DOM K-OMS-2/SiO2 oxide catalysts were firstly used in soot particle oxidation reaction and they show very high catalytic activities. The high activities of K-OMS-2/SiO2 oxide catalysts can be assigned to three possible reasons: macroporous effect of 3DOM structure for improving contact between soot and catalyst, microporous effect of K-OMS-2 for adsorption of small gas molecules and interaction of K and Mn for activation of gas molecules. The catalytic activities of catalysts are comparable to or even higher than noble metal catalyst in the medium and high temperature range. For example, the T50 of K-OMS-2/SiO2-50, 328 °C, is much lower than those of Pt/Al2O3 and 3DOM Au/LaFeO3, 464 and 356 °C,respectively. Moreover, catalysts exhibited high catalytic stability. It is attributed to that the K+ ions are introduced into the microporous structure of OMS-2 and stabilized in the catalytic reaction. Meanwhile, the K+ ions play an important role in templating and stabilizing the tunneled framework of OMS-2. PMID:28443610

  4. Soot and Sulfuric Acid from Aircraft: Is There Enough to Cause Detrimental Environmental E-kCTSs?

    NASA Technical Reports Server (NTRS)

    Pueschel, R. F.; Strawa, A. W.; Ferry, G. V.; Howard, S. D.; Verma, S.

    1998-01-01

    Aerosol from aircraft can affect the environment in three ways: First, soot aerosol has been implicated to cause Icing-tern ozone depletion at mid-latitudes in the lower stratosphere at a rate of approx. 5% per decade. This effect is in addition and unrelated to the polar ozone holes which are strongly influenced by heterogeneous chemistry on polar stratospheric clouds. Second, the most obvious effect of jet aircraft is the formation of visible contrails in the upper troposphere. The Salt Lake City region experienced an 8% increase in cirrus cloud cover over a 15-year period which covariates with an increase in regional commercial air traffic. If soot particles act as freezing nuclei to cause contrail formation heterogeneously, they would be linked to a secondary effect to cloud modification that very likely is climatologically important. Third, a buildup of soot aerosol could reduce the single scatter albedo of stratospheric aerosol from 0.993+0.004 to 0.98, a critical value that has been postulated to separate stratospheric cooling from warming. Thus arises an important question: Do aircraft emit sufficient amounts of soot to have detrimental effects and warrant emission controls? During the 1996 SUCCESS field campaign, we sampled aerosols in the exhaust wake of a Boeing 757 aircraft and determined emission indices for sulfuric acid (EI(sub H2SO4) = 9.0E-2 and 5.0E-1 g/kg (sub FUEL) for 75 and 675 ppm fuel-sulfur, respectively) and soot aerosol (2.2E-3 less than EI(sub SOOT) = l.lE-2 g/kg (sub FUEL)). The soot particle analysis accounted for their fractal nature, determined electron-microscopically, which enhanced the surface area by a factor of 26 and the volume 11-fold over equivalent-volume spheres. The corresponding fuel-sulfur to H2SO4 conversion efficiency was 10% (for 675 ppmm fuel-S) and 37% (for 75 ppmm fuel-S). Applying the H2SO4 emission index to the 1990 fuel use by the worlds commercial fleets of 1.3E11 kg, a conversion efficiency of 30% of 500 ppmm

  5. Optics of Water Microdroplets with Soot Inclusions: Exact Versus Approximate Results

    NASA Technical Reports Server (NTRS)

    Liu, Li; Mishchenko, Michael I.

    2016-01-01

    We use the recently generalized version of the multi-sphere superposition T-matrix method (STMM) to compute the scattering and absorption properties of microscopic water droplets contaminated by black carbon. The soot material is assumed to be randomly distributed throughout the droplet interior in the form of numerous small spherical inclusions. Our numerically-exact STMM results are compared with approximate ones obtained using the Maxwell-Garnett effective-medium approximation (MGA) and the Monte Carlo ray-tracing approximation (MCRTA). We show that the popular MGA can be used to calculate the droplet optical cross sections, single-scattering albedo, and asymmetry parameter provided that the soot inclusions are quasi-uniformly distributed throughout the droplet interior, but can fail in computations of the elements of the scattering matrix depending on the volume fraction of soot inclusions. The integral radiative characteristics computed with the MCRTA can deviate more significantly from their exact STMM counterparts, while accurate MCRTA computations of the phase function require droplet size parameters substantially exceeding 60.

  6. The effects of sooting in droplet combustion

    NASA Technical Reports Server (NTRS)

    Lee, Kyeong-Ook; Jensen, Kirk; Choi, Mun Young

    1995-01-01

    The study of the burning of a single droplet is an ideal problem from which to gain fundamental understanding of diffusion flame characteristics. Droplet combustion is a complex physico-chemical process that involves a chemically-reacting two-phase flow with phase changes and yet simple experiments and analysis can be used to attain important insights into the burning rate, flame dynamics, kinetic extinction and disruption processes. It is a subject that has been actively studied for the past 40 years with most of the fundamental experiments being performed under reduced-gravity conditions for direct comparisons with theoretical/computational analyses that invoke spherical symmetry assumptions. In the earlier studies, the effects of sooting on the overall burning characteristics were not considered. However, recent microgravity investigations performed at the NASA-LeRC droptowers (Droplet Combustion Experiment) and others indicate that effects of soot and sootcloud formation may be significant during the lifetime of the droplet and therefore must be included in the analysis.

  7. Optical characterization of multi-scale morphologically complex heterogeneous media - Application to snow with soot impurities

    NASA Astrophysics Data System (ADS)

    Dai, Xiaoyu; Haussener, Sophia

    2018-02-01

    A multi-scale methodology for the radiative transfer analysis of heterogeneous media composed of morphologically-complex components on two distinct scales is presented. The methodology incorporates the exact morphology at the various scales and utilizes volume-averaging approaches with the corresponding effective properties to couple the scales. At the continuum level, the volume-averaged coupled radiative transfer equations are solved utilizing (i) effective radiative transport properties obtained by direct Monte Carlo simulations at the pore level, and (ii) averaged bulk material properties obtained at particle level by Lorenz-Mie theory or discrete dipole approximation calculations. This model is applied to a soot-contaminated snow layer, and is experimentally validated with reflectance measurements of such layers. A quantitative and decoupled understanding of the morphological effect on the radiative transport is achieved, and a significant influence of the dual-scale morphology on the macroscopic optical behavior is observed. Our results show that with a small amount of soot particles, of the order of 1ppb in volume fraction, the reduction in reflectance of a snow layer with large ice grains can reach up to 77% (at a wavelength of 0.3 μm). Soot impurities modeled as compact agglomerates yield 2-3% lower reduction of the reflectance in a thick show layer compared to snow with soot impurities modeled as chain-like agglomerates. Soot impurities modeled as equivalent spherical particles underestimate the reflectance reduction by 2-8%. This study implies that the morphology of the heterogeneities in a media significantly affects the macroscopic optical behavior and, specifically for the soot-contaminated snow, indicates the non-negligible role of soot on the absorption behavior of snow layers. It can be equally used in technical applications for the assessment and optimization of optical performance in multi-scale media.

  8. Analysis of large oxygenated and nitrated polycyclic aromatic hydrocarbons formed under simulated diesel engine exhaust conditions (by compound fingerprints with SPE/LC-API-MS)

    PubMed Central

    Adelhelm, Christoph; Niessner, Reinhard; Pöschl, Ulrich

    2008-01-01

    The analysis of organic compounds in combustion exhaust particles and the chemical transformation of soot by nitrogen oxides are key aspects of assessment and mitigation of the climate and health effects of aerosol emissions from fossil fuel combustion and biomass burning. In this study we present experimental and analytical techniques for efficient investigation of oxygenated and nitrated derivatives of large polycyclic aromatic hydrocarbons (PAHs), which can be regarded as well-defined soot model substances. For coronene and hexabenzocoronene exposed to nitrogen dioxide under simulated diesel exhaust conditions, several reaction products with high molecular mass could be characterized by liquid chromatography-atmospheric pressure chemical (and photo) ionization-mass spectrometry (LC-APCI-MS and LC-APPI-MS). The main products of coronene contained odd numbers of nitrogen atoms (m/z 282, 256, 338), whereas one of the main products of hexabenzocoronene exhibited an even number of nitrogen atoms (m/z 391). Various reaction products containing carbonyl and nitro groups could be tentatively identified by combining chromatographic and mass spectrometric information, and changes of their relative abundance were observed to depend on the reaction conditions. This analytical strategy should highlight a relatively young technique for the characterization of various soot-contained, semi-volatile, and semi-polar reaction products of large PAHs. Figure LC-APCI-MS analysis of nitrated coronene (and HBC): Total-Ion-Chromatogram (TIC), Extracted Ion Chromatograms (EICs) and corresponding mass spectrum (top). PMID:18560812

  9. COSMIC: Carbon Monoxide and Soot in Microgravity Inverse Combustion

    NASA Technical Reports Server (NTRS)

    Blevins, L. G.; Fernandez, M. G.; Mulholland, G. W.; Davis, R. W.; Moore, E. F.; Steel, E. B.; Scott, J. H. J.

    2001-01-01

    Almost seventy percent of deaths in accidental fires are caused by inhalation of toxins such as carbon monoxide (CO) and smoke (soot) that form during underventilated burning. The COSMIC project examines the formation mechanisms of CO and soot during underventilated combustion, achieved presently using laminar, inverse diffusion flames (IDFs) formed between an air jet and surrounding fuel. A major hypothesis of the project is that the IDF mimics underventilated combustion because carbon-containing species that form on the fuel side of the flame (such as CO and soot) can escape without passing through an oxidizing flame tip. An IDF literature review was presented at the last microgravity workshop, and a few additional IDF papers have appeared since that meeting. The COSMIC project is entering the third year of its four-year funding cycle. The first two years have been devoted to designing and constructing a rig for use in the NASA 2.2-second drop tower. A few computations and laboratory experiments have been performed. The goals of this paper are to discuss the use of numerical simulation during burner design, to present computational and experimental results that support the hypothesis that IDFs are similar to underventilated flames, and to delineate future plans.

  10. Fuel Preheat Effects on Soot-Field Structure in Laminar Gas Jet Diffusion Flames Burning in 0-g and 1-g

    NASA Technical Reports Server (NTRS)

    Konsur, Bogdan; Megaridis, Constantine M.; Griffin, Devon W.

    1999-01-01

    An experimental investigation conducted at the 2.2-s drop tower of the NASA Lewis Research Center is presented to quantify the influence of moderate fuel preheat on soot-field structure within 0-g laminar gas jet diffusion flames. Parallel work in 1-g is also presented to delineate the effect of elevated fuel temperatures on soot-field structure in buoyant flames. The experimental methodology implements jet diffusion flames of nitrogen-diluted acetylene fuel burning in quiescent air at atmospheric pressure. Fuel preheat of approximately 100 K in the 0-g laminar jet diffusion flames is found to reduce soot loadings in the annular region, but causes an increase in soot volume fractions at the centerline. In addition, fuel preheat reduces the radial extent of the soot field in 0-g. In 1-g, the same fuel preheat levels have a more moderated influence on soot loadings in the annular region, but are also seen to enhance soot concentrations near the axis low in the flame. The increased soot loadings near the flame centerline, as caused by fuel preheat, are consistent with the hypothesis that preheat levels of approximately 100 K enhance fuel pyrolysis rates. The results show that the growth stage of particles transported along the soot annulus is shortened both in 1-g and 0-g when elevated fuel temperatures are used.

  11. Delayed condensation and frost formation on superhydrophobic carbon soot coatings by controlling the presence of hydrophilic active sites

    NASA Astrophysics Data System (ADS)

    Esmeryan, Karekin D.; Castano, Carlos E.; Mohammadi, Reza; Lazarov, Yuliyan; Radeva, Ekaterina I.

    2018-02-01

    Condensation frosting is an undesired natural phenomenon that could be impeded efficiently using appropriate wettability and morphologically patterned surfaces. The icephobic properties of carbon soot and the fabrication scalability of its synthesis method are a good foundation for anti-frosting applications; however, the fundamentals of frost growth and spreading on sooted surfaces have not been examined yet. In this study, we investigate the anti-frosting performance of three groups of superhydrophobic soot coatings by means of 16 MHz quartz crystal microbalances (QCMs). The analysis of the real-time sensor signal of each soot coated QCM pattern shows that frost formation and its propagation velocity depend on the quantity of oxygen functionalities and structural defects in the material. In turn, the reduction of both parameters shifts the onset of frost growth to temperatures below  -20 °C, whereas the interdroplet ice bridging is slowed by a factor of four. Moreover, high-resolution scanning electron micrographs of the samples imply delamination upon defrosting of the soot with spherical-like morphology via polar interactions driven mechanism. These results reveal an opportunity for control of frost incipiency on sooted surfaces by adjusting the synthesis conditions and depositing soot coatings with as low as possible content of hydrophilic active sites.

  12. Extinction and Scattering Properties of Soot Emitted from Buoyant Turbulent Diffusion Flames. Appendix F

    NASA Technical Reports Server (NTRS)

    Krishnan, S. S.; Lin, K.-C.; Faeth, G. M.; Yuan, Z.-G. (Technical Monitor); Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

    2001-01-01

    Extinction and scattering properties at wavelengths of 250-5200 nm were studied for soot emitted from buoyant turbulent diffusion flames in the long residence time regime where soot properties are independent of position in the overfire region and characteristic flame residence times. Flames burning in still air and fueled with gas (acetylene, ethylene, propane, and propylene) and liquid (benzene, toluene, cyclohexane, and n-heptane) hydrocarbon fuels were considered. Measured scattering patterns and ratios of total scattering/absorption cross sections were in good agreement with predictions based on the Rayleigh-Debye-Gans (RDG) scattering approximation in the visible. Measured depolarization ratios were roughly correlated by primary particle size parameter, suggesting potential for completing RDG methodology needed to make soot scattering predictions as well as providing a nonintrusive way to measure primary soot particle diameters. Measurements of dimensionless extinction coefficients were in good agreement with earlier measurements for similar soot populations and were independent of fuel type and wavelength except for reduced values as the near ultraviolet was approached. The ratios of the scattering/absorption refractive index functions were independent of fuel type within experimental uncertainties and were in good agreement with earlier measurements. The refractive index junction for absorption was similarly independent of fuel type but was larger than earlier reflectometry measurements in the infrared. Ratios of total scattering/absorption cross sections were relatively large in the visible and near infrared, with maximum values as large as 0.9 and with values as large as 0.2 at 2000 nm, suggesting greater potential for scattering from soot particles to affect flame radiation properties than previously thought.

  13. Extinction and Scattering Properties of Soot Emitted from Buoyant Turbulent Diffusion Flames. Appendix D

    NASA Technical Reports Server (NTRS)

    Krishnan, S. S.; Lin, K.-C.; Faeth, G. M.; Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

    2001-01-01

    Extinction and scattering properties at wavelengths of 250-5200 nm were studied for soot emitted from buoyant turbulent diffusion flames in the long residence time regime where soot properties are independent of position in the overfire region and characteristic flame residence times. Flames burning in still air and fueled with gas (acetylene, ethylene, propane, and propylene) and liquid (benzene, toluene, cyclohexane, and n-heptane) hydrocarbon fuels were considered Measured scattering patterns and ratios of total scattering/absorption cross sections were in good agreement with predictions based on the Rayleigh-Debye-Gans (RDG) scattering approximation in the visible. Measured depolarization ratios were roughly correlated by primary particle size parameter, suggesting potential for completing RDG methodology needed to make soot scattering predictions as well as providing a nonintrusive way to measure primary soot particle diameters. Measurements of dimensionless extinction coefficients were in good agreement with earlier measurements for similar soot populations and were independent of fuel type and wavelength except for reduced values as the near ultraviolet was approached. The ratios of the scattering/absorption refractive index functions were independent of fuel type within experimental uncertainties and were in good agreement with earlier measurements. The refractive index function for absorption was similarly independent of fuel type but was larger than earlier reflectometry measurements in the infrared. Ratios of total scattering/absorption cross sections were relatively large in the visible and near infrared, with maximum values as large as 0.9 and with values as large as 0.2 at 2000 nm, suggesting greater potential for scattering from soot particles to affect flame radiation properties than previously thought.

  14. Characterization of a humic acid-like brown substance in airborne particulate matter and tentative identification of its origin

    NASA Astrophysics Data System (ADS)

    Mukai, Hitoshi; Ambe, Yoshinari

    A brown substance having the solubility characteristics of humic acid was extracted from airborne particulate matter sampled in a rural area of Japan. This brown substance contributed 0.6-3% of the total carbon in airborne particulate matter. This fraction also contained pollen protein in samples collected during the pollen season. Patterns of elution from gel permeation chromatography suggested a molecular weight range from 500 to 10,000, with a still higher upper limit for one sample. The infrared spectra were compared with those of humic acid from the local soil, extracts from dead leaves, smoke from burning plant matter, and soot from automotive exhaust, all possible sources of the brown substance. The closest similarity was with the extract smoke. This identification is strengthened by lack of correlation of the brown substance with aluminum, a tracer for soil content, and a value of K/Fe ratio in the associated particulate matter higher than any plausible source other than combustion. It is probable that the primary source of this brown, high molecular weight acidic materials is agricultural burning.

  15. An Experimental and Computational Study on Soot Formation in a Coflow Jet Flame Under Microgravity and Normal Gravity

    NASA Technical Reports Server (NTRS)

    Ma, Bin; Cao, Su; Giassi, Davide; Stocker, Dennis P.; Takahashi, Fumiaki; Bennett, Beth Anne V.; Smooke, Mitchell D.; Long, Marshall B.

    2014-01-01

    Upon the completion of the Structure and Liftoff in Combustion Experiment (SLICE) in March 2012, a comprehensive and unique set of microgravity coflow diffusion flame data was obtained. This data covers a range of conditions from weak flames near extinction to strong, highly sooting flames, and enabled the study of gravitational effects on phenomena such as liftoff, blowout and soot formation. The microgravity experiment was carried out in the Microgravity Science Glovebox (MSG) on board the International Space Station (ISS), while the normal gravity experiment was performed at Yale utilizing a copy of the flight hardware. Computational simulations of microgravity and normal gravity flames were also carried out to facilitate understanding of the experimental observations. This paper focuses on the different sooting behaviors of CH4 coflow jet flames in microgravity and normal gravity. The unique set of data serves as an excellent test case for developing more accurate computational models.Experimentally, the flame shape and size, lift-off height, and soot temperature were determined from line-of-sight flame emission images taken with a color digital camera. Soot volume fraction was determined by performing an absolute light calibration using the incandescence from a flame-heated thermocouple. Computationally, the MC-Smooth vorticity-velocity formulation was employed to describe the chemically reacting flow, and the soot evolution was modeled by the sectional aerosol equations. The governing equations and boundary conditions were discretized on an axisymmetric computational domain by finite differences, and the resulting system of fully coupled, highly nonlinear equations was solved by a damped, modified Newtons method. The microgravity sooting flames were found to have lower soot temperatures and higher volume fraction than their normal gravity counterparts. The soot distribution tends to shift from the centerline of the flame to the wings from normal gravity to

  16. Reformulated diesel fuel

    DOEpatents

    McAdams, Hiramie T [Carrollton, IL; Crawford, Robert W [Tucson, AZ; Hadder, Gerald R [Oak Ridge, TN; McNutt, Barry D [Arlington, VA

    2006-03-28

    Reformulated diesel fuels for automotive diesel engines which meet the requirements of ASTM 975-02 and provide significantly reduced emissions of nitrogen oxides (NO.sub.x) and particulate matter (PM) relative to commercially available diesel fuels.

  17. The immersion freezing behavior of size-segregated soot and kaolinite particles

    NASA Astrophysics Data System (ADS)

    Hartmann, S.; Augustin, S.; Clauss, T.; Niedermeier, D.; Raddatz, M.; Wex, H.; Shaw, R. A.; Stratmann, F.

    2011-12-01

    Heterogeneous ice nucleation plays a crucial role for ice formation in mixed-phase and cirrus clouds and has an important impact on precipitation formation, global radiation balances, and therefore Earth's climate (Cantrell and Heymsfield, 2005). Mineral dust and soot particles are found to be a major component of ice crystal residues (e.g., Pratt et al., 2009) so these substances are potential sources of atmospheric ice nuclei (IN). Experimental studies investigating the immersion freezing behavior of size-segregated soot and kaolinite particles conducted at the Leipzig Aerosol Cloud Interaction Simulator (LACIS) are presented. In our measurements only one aerosol particle is immersed in an air suspended water droplet which can trigger ice nucleation. The method facilitates very precise examinations with respect to temperature, ice nucleation time and ice nucleus size. Considering laboratory studies, the picture of the IN ability of soot particles is quite heterogeneous. Our studies show that submicron flame, spark soot particles and optionally coated with sulfuric acid to simulate chemically aging do not act as IN at temperatures higher than homogeneous freezing taking place. Therefore soot particles might not be an important source of IN for immersion freezing in the atmosphere. In contrast, kaolinite being representative for natural mineral dust with a well known composition and structure is found to be very active in forming ice for all freezing modes (e.g., Mason and Maybank, 1958). Analyzing the immersion freezing behavior of different sized kaolinite particles (300, 500 and 700 nm in diameter) the size effect was clearly observed, i.e. the ice fraction (number of frozen droplets per total number) scales with particle surface, i.e. the larger the ice nucleus surface the higher the ice fraction. The slope of the logarithm of the ice fraction as function of temperature is similar for all particle sizes investigated and fits very well with the results of L

  18. A unified intermediate and mechanism for soot combustion on potassium-supported oxides

    PubMed Central

    Li, Qian; Wang, Xiao; Xin, Ying; Zhang, Zhaoliang; Zhang, Yexin; Hao, Ce; Meng, Ming; Zheng, Lirong; Zheng, Lei

    2014-01-01

    The soot combustion mechanism over potassium-supported oxides (MgO, CeO2 and ZrO2) was studied to clarify the active sites and discover unified reaction intermediates in this typical gas-solid-solid catalytic reaction. The catalytically active sites were identified as free K+ rather than K2CO3, which can activate gaseous oxygen. The active oxygen spills over to soot and forms a common intermediate, ketene, before it was further oxidized into the end product CO2. The existence of ketene species was confirmed by density functional theory (DFT) calculations. The oxygen spillover mechanism is proposed, which is explained as an electron transfer from soot to gaseous oxygen through the active K+ sites. The latter mechanism is confirmed for the first time since it was put forward in 1950, not only by ultraviolet photoelectron spectroscopy (UPS) results but also by semi-empirical theoretical calculations. PMID:24740213

  19. Performance of diesel engine using diesel B3 mixed with crude palm oil.

    PubMed

    Namliwan, Nattapong; Wongwuttanasatian, Tanakorn

    2014-01-01

    The objective of this study was to test the performance of diesel engine using diesel B3 mixed with crude palm oil in ratios of 95 : 5, 90 : 10, and 85 : 15, respectively, and to compare the results with diesel B3. According to the tests, they showed that the physical properties of the mixed fuel in the ratio of 95 : 5 were closest to those of diesel B3. The performance of the diesel engine that used mixed fuels had 5-17% lower torque and power than that of diesel B3. The specific fuel consumption of mixed fuels was 7-33% higher than using diesel B3. The components of gas emissions by using mixed fuel had 1.6-52% fewer amount of carbon monoxide (CO), carbon dioxide (CO2), sulfur dioxide (SO2), and oxygen (O2) than those of diesel B3. On the other hand, nitric oxide (NO) and nitrogen oxides (NO X ) emissions when using mixed fuels were 10-39% higher than diesel B3. By comparing the physical properties, the performance of the engine, and the amount of gas emissions of mixed fuel, we found out that the 95 : 5 ratio by volume was a suitable ratio for agricultural diesel engine (low-speed diesel engine).

  20. The Impact of Buoyancy and Flame Structure on Soot, Radiation and NOx Emissions from a Turbulent Diffusion Flame

    NASA Technical Reports Server (NTRS)

    Kennedy, I. M.; Kollman, W.; VanderWal, R. L.

    1999-01-01

    It is hypothesized that the spatial structure of a turbulent diffusion flame plays an important role in determining the emissions of radiative energy, soot and NO, from a combustor. This structure, manifested in the two point statistics, is influenced by buoyancy. Radiation, soot and NOx emissions are the cumulative result of processes that occur throughout a flame. For example, radiation fluxes along a line of sight can be found from summing up the contributions from sources in individual pockets of hot soot that emit, and from sinks in cold soot that absorb. Soot and NOx are both the results of slow chemistry and are not equilibrium products. The time that is available for production and burnout is crucial in determining the eventual emissions of these pollutants. Turbulence models generally rely on a single point closure of the appropriate time averaged equations. Hence, spatial information is lost and needs to be modeled using solution variables such as turbulence kinetic energy and dissipation rate, often with the assumption of isotropy. However, buoyancy can affect the physical structure of turbulent flames and can change the spatial extent of soot bearing regions. Theoretical comparisons with models are best done in the limit of infinite Froude number because the inclusion of buoyancy in flow models introduces significant uncertainties. Hence, LII measurements of soot, measurements of radiation fluxes from soot, Particle Imaging Velocimetry (PIV) of the flow field and measurements of post flame NOX will be carried out on the NASA Lewis 2.2 sec drop tower and eventually on the parabolic flight aircraft. The drop rig will be a modified version of a unit that has been successfully used at Lewis in the past.

  1. Performance of Diesel Engine Using Diesel B3 Mixed with Crude Palm Oil

    PubMed Central

    Namliwan, Nattapong; Wongwuttanasatian, Tanakorn

    2014-01-01

    The objective of this study was to test the performance of diesel engine using diesel B3 mixed with crude palm oil in ratios of 95 : 5, 90 : 10, and 85 : 15, respectively, and to compare the results with diesel B3. According to the tests, they showed that the physical properties of the mixed fuel in the ratio of 95 : 5 were closest to those of diesel B3. The performance of the diesel engine that used mixed fuels had 5–17% lower torque and power than that of diesel B3. The specific fuel consumption of mixed fuels was 7–33% higher than using diesel B3. The components of gas emissions by using mixed fuel had 1.6–52% fewer amount of carbon monoxide (CO), carbon dioxide (CO2), sulfur dioxide (SO2), and oxygen (O2) than those of diesel B3. On the other hand, nitric oxide (NO) and nitrogen oxides (NOX) emissions when using mixed fuels were 10–39% higher than diesel B3. By comparing the physical properties, the performance of the engine, and the amount of gas emissions of mixed fuel, we found out that the 95 : 5 ratio by volume was a suitable ratio for agricultural diesel engine (low-speed diesel engine). PMID:24688402

  2. Effects of C/O Ratio and Temperature on Sooting Limits of Spherical Diffusion Flames

    NASA Technical Reports Server (NTRS)

    Lecoustre, V. R.; Sunderland, P. B.; Chao, B. H.; Urban, D. L.; Stocker, D. P.; Axelbaum, R. L.

    2008-01-01

    Limiting conditions for soot particle inception in spherical diffusion flames were investigated numerically. The flames were modeled using a one-dimensional, time accurate diffusion flame code with detailed chemistry and transport and an optically thick radiation model. Seventeen normal and inverse flames were considered, covering a wide range of stoichiometric mixture fraction, adiabatic flame temperature, residence time and scalar dissipation rate. These flames were previously observed to reach their sooting limits after 2 s of microgravity. Sooting-limit diffusion flames with scalar dissipation rate lower than 2/s were found to have temperatures near 1400 K where C/O = 0.51, whereas flames with greater scalar dissipation rate required increased temperatures. This finding was valid across a broad range of fuel and oxidizer compositions and convection directions.

  3. Soot and short-lived pollutants provide political opportunity

    NASA Astrophysics Data System (ADS)

    Victor, David G.; Zaelke, Durwood; Ramanathan, Veerabhadran

    2015-09-01

    Cutting levels of soot and other short-lived pollutants delivers tangible benefits and helps governments to build confidence that collective action on climate change is feasible. After the Paris climate meeting this December, actually reducing these pollutants will be essential to the credibility of the diplomatic process.

  4. The effect of soot on ammonium nitrate species and NO2 selective catalytic reduction over Cu-zeolite catalyst-coated particulate filter.

    PubMed

    Mihai, Oana; Tamm, Stefanie; Stenfeldt, Marie; Olsson, Louise

    2016-02-28

    A selective catalytic reduction (SCR)-coated particulate filter was evaluated by means of dynamic tests performed using NH3, NO2, O2 and H2O. The reactions were examined both prior to and after soot removal in order to study the effect of soot on ammonium nitrate formation and decomposition, ammonia storage and NO2 SCR. A slightly larger ammonia storage capacity was observed when soot was present in the sample, which indicated that small amounts of ammonia can adsorb on the soot. Feeding of NO2 and NH3 in the presence of O2 and H2O at low temperature (150, 175 and 200°C) leads to a large formation of ammonium nitrate species and during the subsequent temperature ramp using H2O and argon, a production of nitrous oxides was observed. The N2O formation is often related to ammonium nitrate decomposition, and our results showed that the N2O formation was clearly decreased by the presence of soot. We therefore propose that in the presence of soot, there are fewer ammonium nitrate species on the surface due to the interactions with the soot. Indeed, we do observe CO2 production during the reaction conditions also at 150°C, which shows that there is a reaction with these species and soot. In addition, the conversion of NOx due to NO2 SCR was significantly enhanced in the presence of soot; we attribute this to the smaller amount of ammonium nitrate species present in the experiments where soot is available since it is well known that ammonium nitrate formation is a major problem at low temperature due to the blocking of the catalytic sites. Further, a scanning electron microscopy analysis of the soot particles shows that they are about 30-40 nm and are therefore too large to enter the pores of the zeolites. There are likely CuxOy or other copper species available on the outside of the zeolite crystallites, which could have been enhanced due to the hydrothermal treatment at 850°C of the SCR-coated filter prior to the soot loading. We therefore propose that soot is

  5. Black carbon surface oxidation and organic composition of beech-wood soot aerosols

    NASA Astrophysics Data System (ADS)

    Corbin, J. C.; Lohmann, U.; Sierau, B.; Keller, A.; Burtscher, H.; Mensah, A. A.

    2015-10-01

    Soot particles are the most strongly light-absorbing particles commonly found in the atmosphere. They are major contributors to the radiative budget of the Earth and to the toxicity of atmospheric pollution. Atmospheric aging of soot may change its health- and climate-relevant properties by oxidizing the primary black carbon (BC) or organic particulate matter (OM) which, together with ash, comprise soot. This atmospheric aging, which entails the condensation of secondary particulate matter as well as the oxidation of the primary OM and BC emissions, is currently poorly understood. In this study, atmospheric aging of wood-stove soot aerosols was simulated in a continuous-flow reactor. The composition of fresh and aged soot particles was measured in real time by a dual-vaporizer aerosol-particle mass spectrometer (SP-AMS). The dual-vaporizer SP-AMS provided information on the OM and BC components of the soot as well as on refractory components internally mixed with BC. By switching the SP-AMS laser vaporizer off and using only the AMS thermal vaporizer (at 600 °C), information on the OM component only was obtained. In both modes, OM appeared to be generated largely by cellulose and/or hemicellulose pyrolysis and was only present in large amounts when new wood was added to the stove. In SP-AMS mode, BC signals otherwise dominated the mass spectrum. These signals consisted of ions related to refractory BC (rBC, C1-5+), oxygenated carbonaceous ions (CO1-2+), potassium (K+), and water (H2O+ and related fragments). The C4+ : C3+ ratio, but not the C1+ : C3+ ratio, was consistent with the BC-structure trends of Corbin et al. (2015c). The CO1-2+ signals likely originated from BC surface groups: upon aging, both CO+ and CO2+ increased relative to C1-3+ while CO2+ simultaneously increased relative to CO+. Factor analysis (positive matrix factorization) of SP-AMS and AMS data, using a modified error model to address peak-integration uncertainties, indicated that the surface

  6. Light scattering and extinction measurements combined with laser-induced incandescence for the real-time determination of soot mass absorption cross section.

    PubMed

    Wei, Yiyi; Ma, Lulu; Cao, Tingting; Zhang, Qing; Wu, Jun; Buseck, Peter R; Thompson, J E

    2013-10-01

    An aerosol albedometer was combined with laser-induced incandescence (LII) to achieve simultaneous measurements of aerosol scattering, extinction coefficient, and soot mass concentration. Frequency doubling of a Nd:YAG laser line resulted in a colinear beam of both λ = 532 and 1064 nm. The green beam was used to perform cavity ring-down spectroscopy (CRDS), with simultaneous measurements of scattering coefficient made through use of a reciprocal sphere nephelometer. The 1064 nm beam was selected and directed into a second integrating sphere and used for LII of light-absorbing kerosene lamp soot. Thermal denuder experiments showed the LII signals were not affected by the particle mixing state when laser peak power was 1.5-2.5 MW. The combined measurements of optical properties and soot mass concentration allowed determination of mass absorption cross section (M.A.C., m(2)/g) with 1 min time resolution when soot concentrations were in the low microgram per cubic meter range. Fresh kerosene nanosphere soot (ns-soot) exhibited a mean M.A.C and standard deviation of 9.3 ± 2.7 m(2)/g while limited measurements on dry ambient aerosol yielded an average of 8.2 ± 5.9 m(2)/g when soot was >0.25 μg/m(3). The method also detected increases in M.A.C. values associated with enhanced light absorption when polydisperse, laboratory-generated ns-soot particles were embedded within or coated with ammonium nitrate, ammonium sulfate, and glycerol. Glycerol coatings produced the largest fractional increase in M.A.C. (1.41-fold increase), while solid coatings of ammonium sulfate and ammonium nitrate produced increases of 1.10 and 1.06, respectively. Fresh, ns-soot did not exhibit increased M.A.C. at high relative humidity (RH); however, lab-generated soot coated with ammonium nitrate and held at 85% RH exhibited M.A.C. values nearly double the low-humidity case. The hybrid instrument for simultaneously tracking soot mass concentration and aerosol optical properties in real time is a

  7. Predicting the effects of nanoscale cerium additives in diesel fuel on regional-scale air quality.

    PubMed

    Erdakos, Garnet B; Bhave, Prakash V; Pouliot, George A; Simon, Heather; Mathur, Rohit

    2014-11-04

    Diesel vehicles are a major source of air pollutant emissions. Fuel additives containing nanoparticulate cerium (nCe) are currently being used in some diesel vehicles to improve fuel efficiency. These fuel additives also reduce fine particulate matter (PM2.5) emissions and alter the emissions of carbon monoxide (CO), nitrogen oxides (NOx), and hydrocarbon (HC) species, including several hazardous air pollutants (HAPs). To predict their net effect on regional air quality, we review the emissions literature and develop a multipollutant inventory for a hypothetical scenario in which nCe additives are used in all on-road and nonroad diesel vehicles. We apply the Community Multiscale Air Quality (CMAQ) model to a domain covering the eastern U.S. for a summer and a winter period. Model calculations suggest modest decreases of average PM2.5 concentrations and relatively larger decreases in particulate elemental carbon. The nCe additives also have an effect on 8 h maximum ozone in summer. Variable effects on HAPs are predicted. The total U.S. emissions of fine-particulate cerium are estimated to increase 25-fold and result in elevated levels of airborne cerium (up to 22 ng/m3), which might adversely impact human health and the environment.

  8. Production Of Fullerenic Soot In Flames

    DOEpatents

    Howard, Jack B.; Vander Sande, John B.; Chowdhury, K. Das

    2000-12-19

    A method for the production of fullerenic nanostructures is described in which unsaturated hydrocarbon fuel and oxygen are combusted in a burner chamber at a sub-atmospheric pressure, thereby establishing a flame. The condensibles of the flame are collected at a post-flame location. The condensibles contain fullerenic nanostructures, such as single and nested nanotubes, single and nested nanoparticles and giant fullerenes. The method of producing fullerenic soot from flames is also described.

  9. Morphological transformation of soot: investigation of microphysical processes during the condensation of sulphuric acid and limonene ozonolysis products vapours

    NASA Astrophysics Data System (ADS)

    Pathak, R. K. P.; Pei, X.; Hallquist, M.; Pagels, J. H.

    2017-12-01

    Morphological transformation of soot particle by condensation of low volatility materials on it is a dominant atmospheric process with serious implications for its optical and hygroscopic properties, and atmospheric lifetime. In this study, the morphological transformation of soot agglomerate under the influence of condensation of vapours of sulphuric acid, and/or limonene ozonolysis products were investigated systematically using a Differential Mobility Analyser-Aerosol Particle Mass Analyser (DMA-APM) and the Tandem DMA techniques integrated with a laminar flow-tube system. We discovered that the morphology transformation of soot in general was a sequence of two-step process, i.e. (i) filling of void space within soot agglomerate; (ii) growth of particle diameter. These two steps followed and complimented each other. In the very beginning the filling was the dominant process followed by growth until it led to the accumulation of enough material that in turn exerted surface forces that eventually facilitated the further filling. The filling of void space was constrained by the initial morphology of fresh soot and the nature and amount of the material condensed. This process continued in several sequential steps until all void space within the soot agglomerate was filled completely and then growth of a spherical particle continued as long as mass was condensed on it. In this study, we developed a framework to quantify the microphysical transformation of soot upon the condensation of various materials. The framework utilized experimental data and hypothesis of ideal sphere growth and filling of voids to quantify the distribution of condensed materials in these two processes complimenting each other. Using this framework, we have quantified the percentage of material that went into processes of particle growth and void filling at each step. Using the same framework, we further estimated the fraction of internal voids and open voids and used this information to derive

  10. Stronger association of polycyclic aromatic hydrocarbons with soot than with char in soils and sediments

    PubMed Central

    Han, Y.M.; Bandowe, B.A.M.; Wei, C.; Cao, J.J.; Wilcke, W.; Wang, G.H.; Ni, H.Y.; Jin, Z.D.; An, Z.S.; Yan, B.Z.

    2016-01-01

    The knowledge of the association of polycyclic aromatic hydrocarbons (PAHs) with organic matter and carbonaceous materials is critical for a better understanding of their environmental transport, fate, and toxicological effects. Extensive studies have been done with regard to the relationship of PAHs with total organic carbon (TOC) and elemental carbon (EC) in different environmental matrices. The relationship between PAHs and the two subtypes of EC, char (combustion residues) and soot (produced via gas-to-particle conversion) also has been tested in field and laboratory experiments using reference materials. However, a direct comparison of associations of PAHs between with char and with soot in real environmental matrices has to our knowledge not yet been reported because of a lack of methodology to differentiate them. In this study, char and soot were measured using the IMPROVE method to test their associations with 12 EPA priority PAHs measured in topsoil samples (N = 22, top 10 cm) collected from the Guanzhong Plain and in surface sediment samples (N = 32, top 5 cm) from the Wei River (central China). In both soils and sediments, Σ12PAHs were more strongly associated with soot than with char, mainly due to the fact that soot and PAHs were produced in the same gas phase during combustion, had a strong affinity for each other, and were transported and deposited together, while char, the combustion residue, was transported differently to PAHs due to its large particle size. Stronger correlations between PAHs and the different carbon fractions (TOC, soot, and char) in sediments than in soils were observed, which is associated with the redistribution of PAHs among the organic matter pools in water because of the processes during soil erosion and sedimentation in the river. PMID:24656973

  11. Modelling of soot formation in laminar diffusion flames using a comprehensive CFD-PBE model with detailed gas-phase chemistry

    NASA Astrophysics Data System (ADS)

    Akridis, Petros; Rigopoulos, Stelios

    2017-01-01

    A discretised population balance equation (PBE) is coupled with an in-house computational fluid dynamics (CFD) code in order to model soot formation in laminar diffusion flames. The unsteady Navier-Stokes, species and enthalpy transport equations and the spatially-distributed discretised PBE for the soot particles are solved in a coupled manner, together with comprehensive gas-phase chemistry and an optically thin radiation model, thus yielding the complete particle size distribution of the soot particles. Nucleation, surface growth and oxidation are incorporated into the PBE using an acetylene-based soot model. The potential of the proposed methodology is investigated by comparing with experimental results from the Santoro jet burner [Santoro, Semerjian and Dobbins, Soot particle measurements in diffusion flames, Combustion and Flame, Vol. 51 (1983), pp. 203-218; Santoro, Yeh, Horvath and Semerjian, The transport and growth of soot particles in laminar diffusion flames, Combustion Science and Technology, Vol. 53 (1987), pp. 89-115] for three laminar axisymmetric non-premixed ethylene flames: a non-smoking, an incipient smoking and a smoking flame. Overall, good agreement is observed between the numerical and the experimental results.

  12. Clean Diesel

    EPA Pesticide Factsheets

    The Clean Diesel Program offers DERA funding in the form of grants and rebates as well as other support for projects that protect human health and improve air quality by reducing harmful emissions from diesel engines.

  13. Characterization of performance-emission indices of a diesel engine using ANFIS operating in dual-fuel mode with LPG

    NASA Astrophysics Data System (ADS)

    Chakraborty, Amitav; Roy, Sumit; Banerjee, Rahul

    2018-03-01

    This experimental work highlights the inherent capability of an adaptive-neuro fuzzy inference system (ANFIS) based model to act as a robust system identification tool (SIT) in prognosticating the performance and emission parameters of an existing diesel engine running of diesel-LPG dual fuel mode. The developed model proved its adeptness by successfully harnessing the effects of the input parameters of load, injection duration and LPG energy share on output parameters of BSFCEQ, BTE, NOX, SOOT, CO and HC. Successive evaluation of the ANFIS model, revealed high levels of resemblance with the already forecasted ANN results for the same input parameters and it was evident that similar to ANN, ANFIS also has the innate ability to act as a robust SIT. The ANFIS predicted data harmonized the experimental data with high overall accuracy. The correlation coefficient (R) values are stretched in between 0.99207 to 0.999988. The mean absolute percentage error (MAPE) tallies were recorded in the range of 0.02-0.173% with the root mean square errors (RMSE) in acceptable margins. Hence the developed model is capable of emulating the actual engine parameters with commendable ranges of accuracy, which in turn would act as a robust prediction platform in the future domains of optimization.

  14. Effects of Turbulence on the Combustion Properties of Partially Premixed Flames of Canola Methyl Ester and Diesel Blends

    DOE PAGES

    Dhamale, N.; Parthasarathy, R. N.; Gollahalli, S. R.

    2011-01-01

    Canola methyl ester (CME) is a biofuel that is a renewable alternative energy resource and is produced by the transesterification of canola oil. The objective of this study was to document the effects of turbulence on the combustion characteristics of blends of CME and No 2 diesel fuel in a partially-premixed flame environment. The experiments were conducted with mixtures of pre-vaporized fuel and air at an initial equivalence ratio of 7 and three burner exit Reynolds numbers, 2700, 3600, and 4500. Three blends with 25, 50, and 75% volume concentration of CME were studied. The soot volume fraction was highestmore » for the pure diesel flames and did not change significantly with Reynolds number due to the mutually compensating effects of increased carbon input rate and increased air entrainment as the Reynolds number was increased. The global NOx emission index was highest and the CO emission index was the lowest for the pure CME flame, and varied non-monotonically with biofuel content in the blend The mean temperature and the NOx concentration at three-quarter flame height were generally correlated, indicating that the thermal mechanism of NOx formation was dominant in the turbulent biofuel flames also.« less

  15. Flow/Soot-Formation Interactions in Nonbuoyant Laminar Diffusion Flames

    NASA Technical Reports Server (NTRS)

    Dai, Z.; Lin, K.-C.; Sunderland, P. B.; Xu, F.; Faeth, G. M.

    2002-01-01

    This is the final report of a research program considering interactions between flow and soot properties within laminar diffusion flames. Laminar diffusion flames were considered because they provide model flame systems that are far more tractable for theoretical and experimental studies than more practical turbulent diffusion flames. In particular, understanding the transport and chemical reaction processes of laminar flames is a necessary precursor to understanding these processes in practical turbulent flames and many aspects of laminar diffusion flames have direct relevance to turbulent diffusion flames through application of the widely recognized laminar flamelet concept of turbulent diffusion flames. The investigation was divided into three phases, considering the shapes of nonbuoyant round laminar jet diffusion flames in still air, the shapes of nonbuoyant round laminar jet diffusion flames in coflowing air, and the hydrodynamic suppression of soot formation in laminar diffusion flames.

  16. Catalytic oxidation of soot on mesoporous ceria-based mixed oxides with cetyltrimethyl ammonium bromide (CTAB)-assisted synthesis.

    PubMed

    Zhu, Hongjian; Xu, Jing; Yichuan, Yuge; Wang, Zhongpeng; Gao, Yibo; Liu, Wei; Yin, Henan

    2017-12-15

    Mesoporous ceria and transition metal-doped ceria (M 0.1 Ce 0.9 O 2 (M=Mn, Fe, Co, Cu)) catalysts were synthesized via CTAB-assisted method. The physicochemical properties of the prepared catalysts were characterized by XRD, DLS analysis, SEM, BET, Raman, H 2 -TPR and in situ DRIFT techniques. The catalytic activity tests for soot oxidation were performed under tight contact of soot/catalyst mixtures in the presence of O 2 and NO+O 2 , respectively. The obtained results show that mesoporous ceria-based solid solutions can be formed with large surface areas and small crystallite size. Transition metals doping enhances the oxygen vacancies and improves redox properties of the solids, resulting in the increased NO oxidation capacity and NO x adsorption capacity. The soot oxidation activity in the presence of O 2 is enhanced by doping transition metal, which may be related to their high surface area, increased oxygen vacancies and improved redox properties. The soot combustion is accelerated by the NO 2 -assisted mechanism under NO+O 2 atmosphere, facilitating an intimate contact between the soot and the catalyst. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Bioacessibility of PAHs in fuel soot assessed by an in vitro digestive model: effect of including an absorptive sink.

    PubMed

    Zhang, Yanyan; Pignatello, Joseph J; Tao, Shu; Xing, Baoshan

    2015-03-17

    Polycyclic aromatic hydrocarbons (PAHs) associated with soot or black carbon can enter the human digestive tract by unintentional ingestion of soil or other particles. This study investigated the bioaccessibility of 11 PAHs in a composite fuel soot sample using an in vitro digestive model that included silicone sheet as an absorptive sink during the small intestinal digestion stage. The sheet was meant to simulate the passive transfer of PAHs in lumen fluid across the small intestinal epithelium, which was postulated to promote desorption of labile PAHs from the soot by steepening the soot-fluid concentration gradient. We show that the presence of silicone sheet during a 4 h default digestion time significantly increased the apparent bioaccessible fraction (Bapp, %), defined as the sum in the sheet and digestive fluid relative to the total PAH determined. The ability to increase Bapp for most PAHs leveled off above a sheet-to-soot ratio of 2.0 g per 50 mg, indicating that the sheet is an effective absorptive sink and promotes desorption in the mentioned way. Enhancement of Bapp by the sheet correlated positively with the octanol-water partition coefficient (Kow), even though the partition coefficient of PAH between sheet and digestive fluid (which contains bile acid micelles) correlated negatively with Kow. It was hypothesized that PAHs initially in the soot exist in labile and nonlabile states. The fraction of labile PAH still sorbed to the soot residue after digestion, and the maximum possible (limiting) bioaccessibility (Blim) could be estimated by varying the sheet-to-soot ratio. We show conclusively that the increase in bioccessibility due to the presence of the sheet is accounted for by a corresponding decrease in fraction of labile PAH still sorbed to the soot. The Blim ranged from 30.8 to 62.4%, independent of molecular size. The nonlabile fraction of individual PAHs (69.2-37.6% in this case) is therefore large and needs to be taken into account in risk

  18. HETEROGENEOUS SOOT NANOSTRUCTURE IN ATMOSPHERIC AND COMBUSTION SOURCE AEROSOLS

    EPA Science Inventory

    Microscopic images of soot emissions from wildfire and a wide range of anthropogenic combustion sources show that the nanostructures of individual particles in these emissions are predominantly heterogeneous, decidedly influenced by the fuel composition and by the particular comb...

  19. Characterization of winter airborne particles at Emperor Qin's Terra-cotta Museum, China.

    PubMed

    Hu, Tafeng; Lee, Shuncheng; Cao, Junji; Chow, Judith C; Watson, John G; Ho, Kinfai; Ho, Wingkei; Rong, Bo; An, Zhisheng

    2009-10-01

    Daytime and nighttime total suspended particulate matters (TSP) were collected inside and outside Emperor Qin's Terra-cotta Museum, the most popular on-site museum in China, in winter 2008. The purpose of this study was to investigate the contribution of visitors to indoor airborne particles in two display halls with different architectural and ventilating conditions, including Exhibition Hall and Pit No.1. Morphological and elemental analyses of 7-day individual particle samples were performed with scanning electron microscopy and energy dispersive X-ray spectrometer (SEM-EDX). Particle mass concentrations in Exhibition Hall and Pit No.1 were in a range of 54.7-291.7 microg m(-3) and 95.3-285.4 microg m(-3) with maximum diameters of 17.5 microm and 26.0 microm, respectively. In most sampling days, daytime/nighttime particle mass ratios in Exhibition Hall (1.30-3.12) were higher than those in Pit No.1 (0.96-2.59), indicating more contribution of the tourist flow in Exhibition Hall than in Pit No. 1. The maximum of particle size distributions were in a range of 0.5-1.0 microm, with the highest abundance (43.4%) occurred in Exhibition Hall at night. The majority of airborne particles at the Museum was composed of soil dust, S-containing particles, and low-Z particles like soot aggregate and biogenic particles. Both size distributions and particle types were found to be associated with visitor numbers in Exhibition Hall and with natural ventilation in Pit No.1. No significant influence of visitors on indoor temperature and relative humidity (RH) was found in either display halls. Those baseline data on the nature of the airborne particles inside the Museum can be incorporated into the maintenance criteria, display management, and ventilation strategy by conservators of the museum.

  20. Remote sensing of soot carbon - Part 2: Understanding the absorption Ångström exponent

    NASA Astrophysics Data System (ADS)

    Schuster, G. L.; Dubovik, O.; Arola, A.; Eck, T. F.; Holben, B. N.

    2016-02-01

    Recently, some authors have suggested that the absorption Ångström exponent (AAE) can be used to deduce the component aerosol absorption optical depths (AAODs) of carbonaceous aerosols in the AERONET database. This AAE approach presumes that AAE ≪ 1 for soot carbon, which contrasts the traditional small particle limit of AAE = 1 for soot carbon. Thus, we provide an overview of the AERONET retrieval, and we investigate how the microphysics of carbonaceous aerosols can be interpreted in the AERONET AAE product. We find that AAE ≪ 1 in the AERONET database requires large coarse mode fractions and/or imaginary refractive indices that increase with wavelength. Neither of these characteristics are consistent with the current definition of soot carbon, so we explore other possibilities for the cause of AAE ≪ 1. AAE is related to particle size, and coarse mode particles have a smaller AAE than fine mode particles for a given aerosol mixture of species. We also note that the mineral goethite has an imaginary refractive index that increases with wavelength, is very common in dust regions, and can easily contribute to AAE ≪ 1. We find that AAE ≪ 1 can not be caused by soot carbon, unless soot carbon has an imaginary refractive index that increases with wavelength throughout the visible and near-infrared spectrums. Finally, AAE is not a robust parameter for separating carbonaceous absorption from dust aerosol absorption in the AERONET database.

  1. Lab-scale Lidar Sensing of Diesel Engines Exhausts

    NASA Technical Reports Server (NTRS)

    Borghese, A.

    1992-01-01

    Combustion technology and its environmental concerns are being considered with increasing attention, not only for global-scale effects, but also for toxicological implications, particularly in the lift conditions of traffic-congested areas and industrial sites. Majority combustion by-products (CO, NO(sub x)) and unburned hydrocarbons (HC), are already subject to increasingly severe regulations; however other, non-regulated minority species, mainly soot and heavy aromatic molecules, involve higher health risks, as they are suspected to be agents of serious pathologies and even mutagenic effects. This is but one of the reasons why much research work is being carried out worldwide on the physical properties of these substances. Correspondingly, the need arises to detect their presence in urban environments, with as high a sensitivity as is required by their low concentrations, proper time- and space-resolutions, and 'real-time' capabilities. Lidar techniques are excellent candidates to this purpose, although severe constraints limit their applicability, eye-safety problems and aerosol Mie scattering uncertainties above all. At CNR's Istituto Motori in Napels, a Lidar-like diagnostic system is being developed, aimed primarily at monitoring the dynamic behavior of internal combustion engines, particularly diesel exhausts, and at exploring the feasibility of a so-called 'Downtown Lidar'.

  2. Shock tube study of the fuel structure effects on the chemical kinetic mechanisms responsible for soot formation, part 2

    NASA Technical Reports Server (NTRS)

    Frenklach, M.; Clary, D. W.; Ramachandra, M. K.

    1985-01-01

    Soot formation in oxidation of allene, 1,3-butadiene, vinylacetylene and chlorobenzene and in pyrolysis of ethylene, vinylacetylene, 1-butene, chlorobenzene, acetylen-hydrogen, benzene-acetylene, benzene-butadiene and chlorobenzene-acetylene argon-diluted mixtures was studied behind reflected shock waves. The results are rationalized within the framework of the conceptual models. It is shown that vinylacetylene is much less sooty than allene, which indicates that conjugation by itself is not a sufficient factor for determining the sooting tendency of a molecule. Structural reactivity in the context of the chemical kinetics is the dominant factor in soot formation. Detailed chemical kinetic modeling of soot formation in pyrolysis of acetylene is reported. The main mass growth was found to proceed through a single dominant route composed of conventional radical reactions. The practically irreversible formation reactions of the fused polycyclic aromatics and the overshoot by hydrogen atom over its equilibrium concentration are the g-driving kinetic forces for soot formation.

  3. Morphology and mixing state of aged soot particles at a remote marine free troposphere site: Implications for optical properties

    DOE PAGES

    China, Swarup; Scarnato, Barbara; Owen, Robert C.; ...

    2015-01-14

    The radiative properties of soot particles depend on their morphology and mixing state, but their evolution during transport is still elusive. In this paper, we report observations from an electron microscopy analysis of individual particles transported in the free troposphere over long distances to the remote Pico Mountain Observatory in the Azores in the North Atlantic. Approximately 70% of the soot particles were highly compact and of those 26% were thinly coated. Discrete dipole approximation simulations indicate that this compaction results in an increase in soot single scattering albedo by a factor of ≤2.17. The top of the atmosphere directmore » radiative forcing is typically smaller for highly compact than mass-equivalent lacy soot. Lastly, the forcing estimated using Mie theory is within 12% of the forcing estimated using the discrete dipole approximation for a high surface albedo, implying that Mie calculations may provide a reasonable approximation for compact soot above remote marine clouds.« less

  4. Effects of laser fluence non-uniformity on ambient-temperature soot measurements using the auto-compensating laser-induced incandescence technique

    NASA Astrophysics Data System (ADS)

    Liu, Fengshan; Rogak, Steven; Snelling, David R.; Saffaripour, Meghdad; Thomson, Kevin A.; Smallwood, Gregory J.

    2016-11-01

    Multimode pulsed Nd:YAG lasers are commonly used in auto-compensating laser-induced incandescence (AC-LII) measurements of soot in flames and engine exhaust as well as black carbon in the atmosphere. Such lasers possess a certain degree of fluence non-uniformity across the laser beam even with the use of beam shaping optics. Recent research showed that the measured volume fraction of ambient-temperature soot using AC-LII increases significantly, by about a factor of 5-8, with increasing the laser fluence in the low-fluence regime from a very low fluence to a relatively high fluence of near sublimation. The causes of this so-called soot volume fraction anomaly are currently not understood. The effects of laser fluence non-uniformity on the measured soot volume fraction using AC-LII were investigated. Three sets of LII experiments were conducted in the exhaust of a MiniCAST soot generator under conditions of high elemental carbon using Nd:YAG lasers operated at 1064 nm. The laser beams were shaped and relay imaged to achieve a relatively uniform fluence distribution in the measurement volume. To further homogenize the laser fluence, one set of LII experiments was conducted by using a diffractive optical element. The measured soot volume fractions in all three sets of LII experiments increase strongly with increasing the laser fluence before a peak value is reached and then start to decrease at higher fluences. Numerical calculations were conducted using the experimental laser fluence histograms. Laser fluence non-uniformity is found partially responsible for the soot volume fraction anomaly, but is insufficient to explain the degree of soot volume fraction anomaly observed experimentally. Representing the laser fluence variations by a histogram derived from high-resolution images of the laser beam energy profile gives a more accurate definition of inhomogeneity than a simple averaged linear profile across the laser beam.

  5. Changes in radiative properties of soot contaminated maize canopy

    NASA Astrophysics Data System (ADS)

    Illes, B.; Anda, A.

    2012-04-01

    The effect of particle (Black Carbon, BC) on certain radiative characteristics of maize plants was studied over 2011 growing season in a field experiment carried out in Keszthely Agrometeorological Research Station. As the main constituent of BC, the soot that is almost exclusively responsible for light absorption by particles in the atmosphere, thus changing the radiation balance of the Earth and contributing to global warming. Maize hybrid Perlona (FAO 340) with short-season was applied as test plant. Of the two water supply treatments, the rainfed variant was sown in field plots, while compensation evapotranspirometers of the Thornthwaite type were used for the "ad libitum" treatment. The BC applied as pollutant was coming from the Hankook Tyre Company (Dunaújváros, Hungary), where it is used to improve the wear resistance of the tyres. The black carbon was chemically "pure", i.e. it is free of other contaminants (heavy metals etc.), so the reproducibility of the experiment is not problematic, unlike that of tests on other atmospheric air pollutants. Road traffic was simulated by using frequent low particle rates (3 g m-2 week-1) with a motorised sprayer of SP 415 type, during the season. The leaf area index was measured each week on the same 12 sample plants in each treatment using an LI 3000A automatic planimeter (LI-COR, Lincoln, NE). The impact of black carbon on plant radiative properties were analysed in the field (about 0.3 ha/treatment). Pyranometers of the CMA-11 type (Kipp & Zonen, Vaisala) were installed on columns of adjustable height in the centre of the 0.3 ha plots designated for albedo measurements. Data were collected using a Logbox SD (Kipp & Zonen, Vaisala) datalogger in the form of 10-minute means of samples taken every 6 seconds. BC pollution had no effect on maize growth and development. Compared with soot contaminated and control plants, we concluded that the LAI was a few percent higher in polluted plants, but this increment was not

  6. Low emissions diesel fuel

    DOEpatents

    Compere, Alicia L.; Griffith, William L.; Dorsey, George F.; West, Brian H.

    1998-01-01

    A method and matter of composition for controlling NO.sub.x emissions from existing diesel engines. The method is achieved by adding a small amount of material to the diesel fuel to decrease the amount of NO.sub.x produced during combustion. Specifically, small amounts, less than about 1%, of urea or a triazine compound (methylol melamines) are added to diesel fuel. Because urea and triazine compounds are generally insoluble in diesel fuel, microemulsion technology is used to suspend or dissolve the urea or triazine compound in the diesel fuel. A typical fuel formulation includes 5% t-butyl alcohol, 4.5% water, 0.5% urea or triazine compound, 9% oleic acid, and 1% ethanolamine. The subject invention provides improved emissions in heavy diesel engines without the need for major modifications.

  7. Low emissions diesel fuel

    DOEpatents

    Compere, A.L.; Griffith, W.L.; Dorsey, G.F.; West, B.H.

    1998-05-05

    A method and matter of composition for controlling NO{sub x} emissions from existing diesel engines. The method is achieved by adding a small amount of material to the diesel fuel to decrease the amount of NO{sub x} produced during combustion. Specifically, small amounts, less than about 1%, of urea or a triazine compound (methylol melamines) are added to diesel fuel. Because urea and triazine compounds are generally insoluble in diesel fuel, microemulsion technology is used to suspend or dissolve the urea or triazine compound in the diesel fuel. A typical fuel formulation includes 5% t-butyl alcohol, 4.5% water, 0.5% urea or triazine compound, 9% oleic acid, and 1% ethanolamine. The subject invention provides improved emissions in heavy diesel engines without the need for major modifications.

  8. Rational strategy for the atmospheric icing prevention based on chemically functionalized carbon soot coatings

    NASA Astrophysics Data System (ADS)

    Esmeryan, Karekin D.; Bressler, Ashton H.; Castano, Carlos E.; Fergusson, Christian P.; Mohammadi, Reza

    2016-12-01

    Although the superhydrophobic surfaces are preferable for passive anti-icing systems, as they provide water shedding before initiation of ice nucleation, their practical usage is still under debate. This is so, as the superhydrophobic materials are not necessarily icephobic and most of the synthesis techniques are characterized with low fabrication scalability. Here, we describe a rational strategy for the atmospheric icing prevention, based on chemically functionalized carbon soot, suitable for large-scale fabrication of superhydrophobic coatings that exhibit and retain icephobicity in harsh operational conditions. This is achieved through a secondary treatment with ethanol and aqueous fluorocarbon solution, which improves the coating's mechanical strength without altering its water repellency. Subsequent experimental analyses on the impact dynamics of icy water droplets on soot coated aluminum and steel sheets show that these surfaces remain icephobic in condensate environments and substrate temperatures down to -35 °C. Furthermore, the soot's icephobicity and non-wettability are retained in multiple icing/de-icing cycles and upon compressed air scavenging, spinning and water jetting with impact velocity of ∼25 m/s. Finally, on frosted soot surfaces, the droplets freeze in a spherical shape and are entirely detached by adding small amount of thermal energy, indicating lower ice adhesion compared to the uncoated metal substrates.

  9. Subsonic Aircraft Soot: A Tracer Documenting Stratospheric Vertical Mixing and Barriers to Inter-Hemispheric Exchanges

    NASA Technical Reports Server (NTRS)

    Pueschel, Rudolf F.; Gore, Warren J. (Technical Monitor)

    1996-01-01

    Pole-to-pole variability of soot aerosol from subsonic aircraft is evidence of two important aspects of stratospheric transport. Vertical transport to 20 km pressure altitude from flight levels near 10-12 km cannot be explained by isentropic mixing. Instead, lofting in the tropics is a possibility. A strong meridional gradient implies that stratospheric soot aerosol residence time is shorter than are mixing times between the hemispheres. Therefore, little if any of exhaust constituents (with residence times similar to that of aircraft soot aerosol), emitted in heavily traveled flight corridors in northern mid-latitudes by a future supersonic fleet, would be transported to the southern hemisphere. However, a significant fraction of NOx could be lofted to altitudes above flight levels where it would dominate ozone depletion.

  10. Effects of airborne black carbon pollution on maize

    NASA Astrophysics Data System (ADS)

    Illes, Bernadett; Anda, Angela; Soos, Gabor

    2013-04-01

    The black carbon (BC) changes the radiation balance of the Earth and contributes to global warming. The airborne BC deposited on the surface of plant, changing the radiation balance, water balance and the total dry matter (TDM) content of plant. The objective of our study was to investigate the impact of soot originated from motor vehicle exhaust on maize. The field experiment was carried out in Keszthely Agrometeorological Research Station (Hungary) in three consecutive years (2010, 2011, 2012) of growing season. The test plant was the maize hybrid Sperlona (FAO 340) with short growing season. The BC was chemically "pure", which means that it is free any contaminants (e.g. heavy metals). The BC was coming from the Hankook Tyre Company (Dunaújváros, Hungary), where used that for improve the wear resistance of tires. We used a motorised sprayer of SP 415 type to spray the BC onto the leaf surface. The leaf area index (LAI) was measured each week on the same 12 sample maize in each treatment using an LI 3000A automatic planimeter (LI-COR, Lincoln, NE). Albedo was measured by pyranometers of the CMA-11 type (Kipp & Zonen, Vaisala), what we placed the middle of the plot of 0.3 ha. The effects of BC were studied under two different water supplies: evapotranspirometers of Thornthwaite type were used for "ad libitum" treatment and rainfed treatment in field plots. In 2010 and 2012, a big difference was not observed in the case of LAI in the effects of BC. However, in 2011 there was a significant difference. The LAI of the BC polluted maize was higher (10-15%, P<0.05), than the LAI of the control maize in the rainfed plot and in the ET chambers, respectively. The albedo of the BC contaminated maize decreased (15-30%, P<0.05) in all three years. We also detected that the green plant surface of maize increased on BC contaminated treatment. These results may suggest that the plant is able to absorb the additional carbon source through the leaves. The albedo decreased

  11. Soot oxidation and NO{sub x} reduction over BaAl{sub 2}O{sub 4} catalyst

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lin, He; Li, Yingjie; Shangguan, Wenfeng

    2009-11-15

    This study addresses soot oxidation and NO{sub x} reduction over a BaAl{sub 2}O{sub 4} catalyst. By XRD analysis, the catalyst was shown to be of spinel structure. Temperature Programmed Oxidation (TPO) and Constant Temperature Oxidation (CTO) at 673 K show that the presence of O{sub 2} decreases the ignition temperature of soot, and it enhances the conversion of NO{sub x} to N{sub 2} and N{sub 2}O. The kinetic features of soot oxidation in the TPO test are similar to that in the TG-DTA analysis. Analysis by Diffuse Reflectance Fourier Infrared Transform Spectroscopy (DRIFTS) indicates that the nitrates formed from NO{submore » x} adsorption and the C(O) intermediates from soot oxidation are the key precursors of the redox process between soot and NO{sub x} over surfaces of the BaAl{sub 2}O{sub 4} catalyst. Moreover, DRIFTS tests suggest that nitrates act as the principal oxidants for C(O) oxidation, through which nitrates are reduced to N{sub 2} and N{sub 2}O. The O{sub 2} in the gas mixture presents a positive effect on the conversion of NO{sub x} to N{sub 2} and N{sub 2}O by promoting the oxidation of nitrites into nitrates species. (author)« less

  12. Suresh K. AggarwalQuantified Analysis of a Production Diesel Injector Using X-Ray Radiography and Engine Diagnostics

    NASA Astrophysics Data System (ADS)

    Ramirez, Anita I.

    phase. Diesel/phytol blends yield marginally lower power values. In-cylinder soot radiation images show combustion instability at the start of the event for the 20% phytol/diesel blend. Overall, NOx emissions are comparable across the different fuels used and no discernible trend is found in CO emissions.

  13. Smog chamber study on aging of combustion soot in isoprene/SO2/NOx system: Changes of mass, size, effective density, morphology and mixing state

    NASA Astrophysics Data System (ADS)

    Li, Kangwei; Chen, Linghong; Han, Ke; Lv, Biao; Bao, Kaiji; Wu, Xuecheng; Gao, Xiang; Cen, Kefa

    2017-02-01

    Atmospheric soot aging process is always accompanied by secondary particle formation, which is a comprehensive environmental issue that deserves great attention. On one hand, aging of primary soot could change its own physicochemical properties; on the other hand, complex air pollution caused by pollutant emission from various sources (e.g., vehicle exhausts, coal-fired flue gases and biogenic VOCs emission) may contribute to secondary particle formation onto primary particle surface. In this study, aging of combustion soot in isoprene/SO2/NOx system was investigated under controlled laboratory conditions in several smog chamber experiments. During the evolution of soot, several physical properties such as mass, size, effective density, morphology and mixing state were determined simultaneously by an integrated aerosol analytical system of Scanning Mobility Particle Sizer (SMPS), Differential Mobility Analyzer-Aerosol Particle Mass Analyzer-Condensation Particle Counter (DMA-APM-CPC) and Transmission Electron Microscopy coupled with Energy-dispersive X-ray Spectrometry (TEM/EDX) techniques. Here, based on the experimental results of soot aging under different gas-phase composition and relative humidity (RH), we firstly proposed possible aging pathways of soot in isoprene/SO2/NOx system. A synergetic effect was speculated to exist between SO2 and isoprene on soot aging process, which led to more secondary particle formation. At the same time, TEM/EDX analysis showed that a competitive mechanism between H2SO4(g) and isoprene oxidation vapor may exist: H2SO4(g) firstly condensed onto fresh soot, then an acceleration of isoprene oxidation products formed onto H2SO4 pre-coated soot. In isoprene/SO2/NOx system, high RH conditions could contribute to soot aging and new particle formation. The changes of effective density and dynamic shape factor of soot also indicated that high RH conditions could accelerate soot aging process, and led chain-like soot into more spherical

  14. Flame and Soot Boundaries of Laminar Jet Diffusion Flames. Appendix A

    NASA Technical Reports Server (NTRS)

    Xu, F.; Dai, Z.; Faeth, G. M.; Yuan, Z.-G. (Technical Monitor); Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

    2002-01-01

    The shapes (flame-sheet and luminous-flame boundaries) or steady weakly buoyant round hydrocarbon-fueled laminar-jet diffusion flames in still and coflowing air were studied both experimentally and theoretically. Flame-sheet shapes were measured from photographs using a CH optical filter to distinguish flame-sheet boundaries in the presence of blue CO2 and OH emissions and yellow continuum radiation from soot. Present experimental conditions included acetylene-, methane-, propane-, and ethylene-fueled flames having initial reactant temperatures of 300 K. ambient pressures of 4-50 kPa, jet-exit Reynolds numbers of 3-54, initial air/fuel velocity ratios of 0-9, and luminous flame lengths of 5-55 mm; earlier measurements for propylene- and 1,3-butadiene-fueled flames for similar conditions were considered as well. Nonbuoyant flames in still air were observed at microgravity conditions; essentially nonbuoyant flames in coflowing air were observed at small pressures to control effects of buoyancy. Predictions of luminous flame boundaries from soot luminosity were limited to laminar smoke-point conditions, whereas predictions of flame-sheet boundaries ranged from soot-free to smoke-point conditions. Flame-shape predictions were based on simplified analyses using the boundary-layer approximations along with empirical parameters to distinguish flame-sheet and luminous-flame (at the laminar smoke point) boundaries. The comparison between measurements and predictions was remarkably good and showed that both flame-sheet and luminous-flame lengths are primarily controlled by fuel flow rates with lengths in coflowing air approaching 2/3 of the lengths in still air as coflowing air velocities are increased. Finally, luminous flame lengths at laminar smoke-point conditions were roughly twice as long as flame-sheet lengths at comparable conditions because of the presence of luminous soot particles in the fuel-lean region of the flames.

  15. Investigation of soot and carbon formation in small gas turbine combustors

    NASA Technical Reports Server (NTRS)

    Rosfjord, T. J.

    1982-01-01

    An investigation of hardware configurations which attempt to minimize carbon and soot-production without sacrificing performance in small gas turbine combustors was conducted. Four fuel injectors, employing either airblast atomization, pressure atomization, or fuel vaporization techniques were combined with nozzle air swirlers and injector sheaths. Eight configurations were screened at sea-level takeoff and idle test conditions. Selected configurations were focused upon in an attempt to quantify the influence of combustor pressure, inlet temperature, primary zone operation, and combustor loading on soot and carbon formation. Cycle tests were also performed. It was found that smoke emission levels depended on the combustor fluid mechanics, the atomization quality of the injector and the fuel hydrogen content.

  16. Superhydrophobicity of hierarchical nanostructure of candle soot films

    NASA Astrophysics Data System (ADS)

    Hankhuntond, A.; Singjai, P.; Sakulsermsuk, S.

    2017-09-01

    Candle soot containing carbon nanoparticles can form hierarchical structure films. We prepared soot films by using glass slides blocking candle flame in the middle of the flame. The hierarchical nanostructures of the carbon nanoparticles films were confirmed by scanning electron microscopy and transmission electron microscopy. Carbon nanoparticle size was 49.2 ± 9.0 nm from SEM, which agrees to 37.9 ± 8.5 nm from TEM. The contact angles of water droplets on these films are more than 150°, indicating superhydrophobic surface. Decrease contact angles of water droplets were observed with an increase deposition time. The decrease of contact angle was saturated at about 150° when the deposition time reaches 180 s. Cassie-Baxter state was attributed to describe superhydrophobicity of carbon nanoparticles films because the hierarchical nanostructures of the surface provide a large fraction of hollows on the surface. We proposed that the contact angle dependence on deposition time was governed by the increase of the distance between nanopillars in carbon nanoparticles films.

  17. Source Estimation of Wintertime Soot Particles for an Urban Site Varanasi (25.30 N, 83.00 E) in Central Indo-Gangetic Plain Region

    NASA Astrophysics Data System (ADS)

    Singh, A. K.; Srivastava, M. K.; Dumka, U. C.; Singh, R. K.; Singh, R. S.; Tiwari, S.; Mehrotra, B. J.; Srivastava, A. K.

    2017-12-01

    Black carbon particles (BC: also called Soot) are formed by incomplete combustion of hydrocarbon based fuels (fossil fuel: coal, diesel, petrol, etc.) as well as due to burning of biomass and bio-fuels (wood, shrubs, dry leaves, etc.). Soot particles are warming agent to the atmosphere that gained wide attention in recent years due to their direct and indirect impacts on local, regional as well as global climate. The climatic effects due to soot are not well understood as indicated by large uncertainties in their climate forcing estimation, particularly in South and East Asian region, possibly due to unavailability of adequate database and information about the source. Measurement of wintertime BC mass concentrations for urban site in central IGP, `Varanasi' (25.30 N, 83.00 E), using a seven wavelength Aethalometer is reported in this work. Delta-C (=BC370 - BC880), which is an indicator of biomass/bio-fuels or residential coal burning is used to understand the source. Aethalometer based source apportionment model "Aethalometer model" was used to apportion the fossil fuel/traffic and wood/biomass burning mass concentration to the total BC mass. The preliminary results for representative month (January-2015) show that daily-average BC mass ranged from 4.47 to 20.70 μg m-3 (Average: 9.45 ± 4.15 μg m-3). The daily Absorption Ångström Exponent (AAE) and the ratio of BCff/BC and BCff/BCwb varied between 1.09 - 1.32, 0.67 - 0.92 and 2 - 40, respectively, due to the changes in BC emissions rates. The total BC, BC from fossil fuel (BCff) and BC from wood/biomass burning (BCwb) behaved in the remarkable diurnal pattern, behaving opposite to the mixing layer heights (MLHs). During daytime, MLHs are higher due to surface based solar warming and causes more volume of atmosphere for the BC dispersion. This phenomenon causes the surface measurement of lower BC mass during the daytime. The data is, however, still being processed for multi-year wintertime observations and the

  18. Identification and characterization of individual airborne volcanic ash particles by Raman microspectroscopy.

    PubMed

    Ivleva, Natalia P; Huckele, Susanne; Weinzierl, Bernadett; Niessner, Reinhard; Haisch, Christoph; Baumann, Thomas

    2013-11-01

    We present for the first time the Raman microspectroscopic identification and characterization of individual airborne volcanic ash (VA) particles. The particles were collected in April/May 2010 during research aircraft flights, which were performed by Deutsches Zentrum für Luft- und Raumfahrt in the airspace near the Eyjafjallajökull volcano eruption and over Europe (between Iceland and Southern Germany). In addition, aerosol particles were sampled by an Electrical Low Pressure Impactor in Munich, Germany. As references for the Raman analysis, we used the spectra of VA collected at the ground near the place of eruption, of mineral basaltic rock, and of different minerals from a database. We found significant differences in the spectra of VA and other aerosol particles (e.g., soot, nitrates, sulfates, and clay minerals), which allowed us to identify VA among other atmospheric particulate matter. Furthermore, while the airborne VA shows a characteristic Raman pattern (with broad band from ca. 200 to ca. 700 cm(-1) typical for SiO₂ glasses and additional bands of ferric minerals), the differences between the spectra of aged and fresh particles were observed, suggesting differences in their chemical composition and/or structure. We also analyzed similarities between Eyjafjallajökull VA particles collected at different sampling sites and compared the particles with a large variety of glassy and crystalline minerals. This was done by applying cluster analysis, in order to get information on the composition and structure of volcanic ash.

  19. Internally mixed sea salt, soot, and sulfates at Macao, a coastal city in South China.

    PubMed

    Li, Weijun; Shao, Longyi; Shen, Rongrong; Yang, Shusheng; Wang, Zhishi; Tang, Uwa

    2011-11-01

    Direct observation of the mixing state of aerosol particles in a coastal urban city is critical to understand atmospheric processing and hygroscopic growth in humid air. Morphology, composition, and mixing state of individual aerosol particles from Macao, located south of the Pearl River Delta (PRD) and 100 km west of Hong Kong, were investigated using scanning electron microscopy (SEM) and transmission electron microscopy coupled with energy-dispersive X-ray spectrometry (TEM/EDX). SEM images show that soot and roughly spherical particles are prevalent in the samples. Based on the compositions of individual aerosol particles, aerosol particles with roughly spherical shape are classified into coarse Na-rich and fine S-rich particles. TEM/EDX indicates that each Na-rich particle consists of a Na-S core and NaNO3 shell. Even in the absence of heavy pollution, the marine sea salt particles were completely depleted in chloride, and Na-related sulfates and nitrates were enriched in Macao air. The reason could be that SO2 from the polluted PRD and ships in the South China Sea and NO2 from vehicles in the city sped up the chlorine depletion in sea salt through heterogeneous reactions. Fresh soot particles from vehicular emissions mainly occur near curbside. However, there are many aged soot particles in the sampling site surrounded by main roads 200 to 400 m away, suggesting that the fresh soot likely underwent a quick aging. Overall, secondary nitrates and sulfates internally mixed with soot and sea salt particles can totally change their surface hygroscopicity in coastal cities.

  20. Diesel bus emissions measured in a tunnel study.

    PubMed

    Jamriska, Milan; Morawska, Lidia; Thomas, Steven; He, Congrong

    2004-12-15

    The emission factors of a bus fleet consisting of approximately 300 diesel-powered buses were measured in a tunnel study under well-controlled conditions during a 2-d monitoring campaign in Brisbane. Particle number and mass concentration levels of submicrometer particles and PM2.5 were monitored by SMPS and DustTrak instruments at the tunnel's entrance and exit, respectively. Correlation between DustTrak and TEOM response to diesel emissions was assessed, and the DustTrak results were recalculated into TEOM equivalent data. The mean value of the number and mass emission factors was (3.11+/-2.41) x 10(14) particles km(-1) for submicrometer particles and 583+/-451 mg km(-1) for PM2.5 (DustTrak), respectively. TEOM PM2.5 equivalent emission factor was 267+/-207 mg km(-1). The results are in good agreement with the emission factors determined from steady-state dynamometer testing of 12 buses from the same Brisbane City bus fleet. The results indicate that when carefully designed, both approaches, the dynamometer and on-road studies, can provide comparable results, applicable for the assessment of the effect of traffic emissions on airborne particle pollution. A brief overview of emission factors determined from other on-road and dynamometer studies reported in the literature as well as with the regulatory values used for the vehicle emission inventory assessment is presented and compared with the results obtained in this study.

  1. Soot Aerosol Particles as Cloud Condensation Nuclei: from Ice Nucleation Activity to Ice Crystal Morphology

    NASA Astrophysics Data System (ADS)

    Pirim, Claire; Ikhenazene, Raouf; Ortega, Isamel Kenneth; Carpentier, Yvain; Focsa, Cristian; Chazallon, Bertrand; Ouf, François-Xavier

    2016-04-01

    Emissions of solid-state particles (soot) from engine exhausts due to incomplete fuel combustion is considered to influence ice and liquid water cloud droplet activation [1]. The activity of these aerosols would originate from their ability to be important centers of ice-particle nucleation, as they would promote ice formation above water homogeneous freezing point. Soot particles are reported to be generally worse ice nuclei than mineral dust because they activate nucleation at higher ice-supersaturations for deposition nucleation and at lower temperatures for immersion freezing than ratios usually expected for homogeneous nucleation [2]. In fact, there are still numerous opened questions as to whether and how soot's physico-chemical properties (structure, morphology and chemical composition) can influence their nucleation ability. Therefore, systematic investigations of soot aerosol nucleation activity via one specific nucleation mode, here deposition nucleation, combined with thorough structural and compositional analyzes are needed in order to establish any association between the particles' activity and their physico-chemical properties. In addition, since the morphology of the ice crystals can influence their radiative properties [3], we investigated their morphology as they grow over both soot and pristine substrates at different temperatures and humidity ratios. In the present work, Combustion Aerosol STandart soot samples were produced from propane using various experimental conditions. Their nucleation activity was studied in deposition mode (from water vapor), and monitored using a temperature-controlled reactor in which the sample's relative humidity is precisely measured with a cryo-hygrometer. Formation of water/ice onto the particles is followed both optically and spectroscopically, using a microscope coupled to a Raman spectrometer. Vibrational signatures of hydroxyls (O-H) emerge when the particle becomes hydrated and are used to characterize ice

  2. Diesels in combined cycle

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kuehn, S.E.

    1995-03-01

    This article examines why the diesel engine is a very attractive choice for producing power in the combined-cycle configuration. The medium-speed diesel is already one of the most efficient simple cycle sources of electricity, especially with lower grade fuels. Large units have heat-rate efficiencies as high as 45%, equating to a heat rate of 7,580 Btu/k Whr, and no other power production prime mover can match this efficiency. Diesels also offer designers fuel flexibility and can burn an extreme variety of fuels without sacrificing many of its positive operating attributes. Diesels are the first building block in a highly efficientmore » combined cycle system that relies on the hot gas and oxygen in the diesel`s exhaust to combust either natural gas, light distillate oil, heavy oil or coal, in a boiler. By using a fired boiler, steam can be generated at sufficient temperature and pressure to operate a Rankine steam cycle efficiently. Diesel combined-cycle plants can be configured in much the same way a gas turbine plant would be. However, the diesel combined-cycle scheme requires supplemental firing to generate appropriate steam conditions. The most efficient cycle, therefore, would not be achieved until combustion air and supplemental fuel are minimized to levels that satisfy steam conditions, steam generation and power generation constraints.« less

  3. Soot formation and radiation in turbulent jet diffusion flames under normal and reduced gravity conditions

    NASA Technical Reports Server (NTRS)

    Ku, Jerry C.; Tong, LI; Sun, Jun; Greenberg, Paul S.; Griffin, Devon W.

    1993-01-01

    Most practical combustion processes, as well as fires and explosions, exhibit some characteristics of turbulent diffusion flames. For hydrocarbon fuels, the presence of soot particles significantly increases the level of radiative heat transfer from flames. In some cases, flame radiation can reach up to 75 percent of the heat release by combustion. Laminar diffusion flame results show that radiation becomes stronger under reduced gravity conditions. Therefore, detailed soot formation and radiation must be included in the flame structure analysis. A study of sooting turbulent diffusion flames under reduced-gravity conditions will not only provide necessary information for such practical issues as spacecraft fire safety, but also develop better understanding of fundamentals for diffusion combustion. In this paper, a summary of the work to date and of future plans is reported.

  4. Experiments and Model Development for the Investigation of Sooting and Radiation Effects in Microgravity Droplet Combustion

    NASA Technical Reports Server (NTRS)

    Choi, Mun Young; Yozgatligil, Ahmet; Dryer, Frederick L.; Kazakov, Andrei; Dobashi, Ritsu

    2001-01-01

    Today, despite efforts to develop and utilize natural gas and renewable energy sources, nearly 97% of the energy used for transportation is derived from combustion of liquid fuels, principally derived from petroleum. While society continues to rely on liquid petroleum-based fuels as a major energy source in spite of their finite supply, it is of paramount importance to maximize the efficiency and minimize the environmental impact of the devices that burn these fuels. The development of improved energy conversion systems, having higher efficiencies and lower emissions, is central to meeting both local and regional air quality standards. This development requires improvements in computational design tools for applied energy conversion systems, which in turn requires more robust sub-model components for combustion chemistry, transport, energy transport (including radiation), and pollutant emissions (soot formation and burnout). The study of isolated droplet burning as a unidimensional, time dependent model diffusion flame system facilitates extensions of these mechanisms to include fuel molecular sizes and pollutants typical of conventional and alternative liquid fuels used in the transportation sector. Because of the simplified geometry, sub-model components from the most detailed to those reduced to sizes compatible for use in multi-dimensional, time dependent applied models can be developed, compared and validated against experimental diffusion flame processes, and tested against one another. Based on observations in microgravity experiments on droplet combustion, it appears that the formation and lingering presence of soot within the fuel-rich region of isolated droplets can modify the burning rate, flame structure and extinction, soot aerosol properties, and the effective thermophysical properties. These observations led to the belief that perhaps one of the most important outstanding contributions of microgravity droplet combustion is the observation that in the

  5. Computations of soot and and NO sub x emissions from gas turbine combustors

    NASA Technical Reports Server (NTRS)

    Srivatsa, S. K.

    1982-01-01

    An analytical program was conducted to compute the soot and NOx emissions from a combustor and the radiation heat transfer to the combustor walls. The program involved the formulation of an emission and radiation model and the incorporation of this model into the Garrett 3-D Combustor Perfomance Computer Program. Computations were performed for the idle, cruise, and take-off conditions of a JT8D can combustor. The predicted soot and NOx emissions and the radiation heat transfer to the combustor walls agree reasonably well with the limited experimental data available.

  6. Fourth Airborne Geoscience Workshop

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The focus of the workshop was on how the airborne community can assist in achieving the goals of the Global Change Research Program. The many activities that employ airborne platforms and sensors were discussed: platforms and instrument development; airborne oceanography; lidar research; SAR measurements; Doppler radar; laser measurements; cloud physics; airborne experiments; airborne microwave measurements; and airborne data collection.

  7. Candle soot nanoparticles-polydimethylsiloxane composites for laser ultrasound transducers

    NASA Astrophysics Data System (ADS)

    Chang, Wei-Yi; Huang, Wenbin; Kim, Jinwook; Li, Sibo; Jiang, Xiaoning

    2015-10-01

    Generation of high power laser ultrasound strongly demands the advanced materials with efficient laser energy absorption, fast thermal diffusion, and large thermoelastic expansion capabilities. In this study, candle soot nanoparticles-polydimethylsiloxane (CSNPs-PDMS) composite was investigated as the functional layer for an optoacoustic transducer with high-energy conversion efficiency. The mean diameter of the collected candle soot carbon nanoparticles is about 45 nm, and the light absorption ratio at 532 nm wavelength is up to 96.24%. The prototyped CSNPs-PDMS nano-composite laser ultrasound transducer was characterized and compared with transducers using Cr-PDMS, carbon black (CB)-PDMS, and carbon nano-fiber (CNFs)-PDMS composites, respectively. Energy conversion coefficient and -6 dB frequency bandwidth of the CSNPs-PDMS composite laser ultrasound transducer were measured to be 4.41 × 10-3 and 21 MHz, respectively. The unprecedented laser ultrasound transduction performance using CSNPs-PDMS nano-composites is promising for a broad range of ultrasound therapy applications.

  8. On the carcinogenic risk evaluation of diesel exhaust: benzene in airborne particles and alterations of heme metabolism in lymphocytes as markers of exposure.

    PubMed

    Muzyka, V; Veimer, S; Schmidt, N

    1998-06-30

    Diesel exhaust consists of a complex mixture of chemicals which contain known genotoxicants, one of which is benzene. Therefore the concentration of benzene may be used in the evaluation of full external exposure to diesel exhaust. Our attention is focused on the determination of the distribution of benzene between the gas and particulate phases in the breathing zone of bus-garage workers. Bus diesel engine exhaust was the main source of air pollution by benzene and particles. The particulate matter contained benzene in amounts comparable to those usually found for concentrations of carcinogenic polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs. A much lower concentration of benzene was associated with particulate matter in the winter than in the summer months. The level of benzene in the gas phase showed a dependence on the distance of workplace from the operating diesel motor. The study indicated that benzene associated with diesel exhaust particles (DEP) might be an important factor to consider when studying diesel exhaust exposure from air pollution sources. Since non-genotoxic effects may play an important role in the generation of tumors by genotoxic carcinogens, the level of heme synthesis was proposed as a biomarker of early health effect. Here we present the data on determination of 5-aminolevulinic acid (ALA) synthesis and heme formation in lymphocytes from a group of 45 bus-garage workers and an analogous data from a group of 25 unexposed subjects. The results indicate significant differences in ALA synthesis and heme formation between the exposed workers when compared to the non-exposed individuals. ALA was accumulated and ALA-synthase activity was increased in lymphocytes of garage workers. At the same time ferrochelatase activity was decreased and protoporphyrin contents were elevated. In addition the concentration of porphyrin associated with DNA was significantly increased. Thus, the measurement of some metabolites of heme synthesis in

  9. Hybrid sparse blind deconvolution: an implementation of SOOT algorithm to real data

    NASA Astrophysics Data System (ADS)

    Pakmanesh, Parvaneh; Goudarzi, Alireza; Kourki, Meisam

    2018-06-01

    Getting information of seismic data depends on deconvolution as an important processing step; it provides the reflectivity series by signal compression. This compression can be obtained by removing the wavelet effects on the traces. The recently blind deconvolution has provided reliable performance for sparse signal recovery. In this study, two deconvolution methods have been implemented to the seismic data; the convolution of these methods provides a robust spiking deconvolution approach. This hybrid deconvolution is applied using the sparse deconvolution (MM algorithm) and the Smoothed-One-Over-Two algorithm (SOOT) in a chain. The MM algorithm is based on the minimization of the cost function defined by standards l1 and l2. After applying the two algorithms to the seismic data, the SOOT algorithm provided well-compressed data with a higher resolution than the MM algorithm. The SOOT algorithm requires initial values to be applied for real data, such as the wavelet coefficients and reflectivity series that can be achieved through the MM algorithm. The computational cost of the hybrid method is high, and it is necessary to be implemented on post-stack or pre-stack seismic data of complex structure regions.

  10. Diesel Vehicle Maintenance Competencies.

    ERIC Educational Resources Information Center

    Braswell, Robert; And Others

    Designed to provide a model set of competencies, this manual presents tasks which were identified by employers, employees, and teachers as important in a postsecondary diesel vehicle maintenance curriculum. The tasks are divided into seven major component areas of instruction: chassis and suspension, diesel engines, diesel fuel, electrical,…

  11. Measurement of the spatially distributed temperature and soot loadings in a laminar diffusion flame using a Cone-Beam Tomography technique

    NASA Astrophysics Data System (ADS)

    Zhao, Huayong; Williams, Ben; Stone, Richard

    2014-01-01

    A new low-cost optical diagnostic technique, called Cone Beam Tomographic Three Colour Spectrometry (CBT-TCS), has been developed to measure the planar distributions of temperature, soot particle size, and soot volume fraction in a co-flow axi-symmetric laminar diffusion flame. The image of a flame is recorded by a colour camera, and then by using colour interpolation and applying a cone beam tomography algorithm, a colour map can be reconstructed that corresponds to a diametral plane. Look-up tables calculated using Planck's law and different scattering models are then employed to deduce the temperature, approximate average soot particle size and soot volume fraction in each voxel (volumetric pixel). A sensitivity analysis of the look-up tables shows that the results have a high temperature resolution but a relatively low soot particle size resolution. The assumptions underlying the technique are discussed in detail. Sample data from an ethylene laminar diffusion flame are compared with data in the literature for similar flames. The comparison shows very consistent temperature and soot volume fraction profiles. Further analysis indicates that the difference seen in comparison with published results are within the measurement uncertainties. This methodology is ready to be applied to measure 3D data by capturing multiple flame images from different angles for non-axisymmetric flame.

  12. Performance of a newly designed continuous soot monitoring system (COSMOS).

    PubMed

    Miyazaki, Yuzo; Kondo, Yutaka; Sahu, Lokesh K; Imaru, Junichi; Fukushima, Nobuhiko; Kano, Minoru

    2008-10-01

    We designed a continuous soot monitoring system (COSMOS) for fully automated, high-sensitivity, continuous measurement of light absorption by black carbon (BC) aerosols. The instrument monitors changes in transmittance across an automatically advancing quartz fiber filter tape using an LED at a 565 nm wavelength. To achieve measurements with high sensitivity and a lower detectable light absorption coefficient, COSMOS uses a double-convex lens and optical bundle pipes to maintain high light intensity and signal data are obtained at 1000 Hz. In addition, sampling flow rate and optical unit temperature are actively controlled. The inlet line for COSMOS is heated to 400 degrees C to effectively volatilize non-refractory aerosol components that are internally mixed with BC. In its current form, COSMOS provides BC light absorption measurements with a detection limit of 0.45 Mm(-1) (0.045 microg m(-3) for soot) for 10 min. The unit-to-unit variability is estimated to be within +/- 1%, demonstrating its high reproducibility. The absorption coefficients determined by COSMOS agreed with those by a particle soot absorption photometer (PSAP) to within 1% (r2 = 0.97). The precision (+/- 0.60 Mm(-1)) for 10 min integrated data was better than that of PSAP and an aethalometer under our operating conditions. These results showed that COSMOS achieved both an improved detection limit and higher precision for the filter-based light absorption measurements of BC compared to the existing methods.

  13. 40 CFR 80.522 - May used motor oil be dispensed into diesel motor vehicles or nonroad diesel engines?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... diesel motor vehicles or nonroad diesel engines? 80.522 Section 80.522 Protection of Environment... Motor Vehicle Diesel Fuel; Nonroad, Locomotive, and Marine Diesel Fuel; and ECA Marine Fuel Motor Vehicle Diesel Fuel Standards and Requirements § 80.522 May used motor oil be dispensed into diesel motor...

  14. 40 CFR 80.522 - May used motor oil be dispensed into diesel motor vehicles or nonroad diesel engines?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... diesel motor vehicles or nonroad diesel engines? 80.522 Section 80.522 Protection of Environment... Motor Vehicle Diesel Fuel; Nonroad, Locomotive, and Marine Diesel Fuel; and ECA Marine Fuel Motor Vehicle Diesel Fuel Standards and Requirements § 80.522 May used motor oil be dispensed into diesel motor...

  15. Effect of Alcohol on Diesel Engine Combustion Operating with Biodiesel-Diesel Blend at Idling Conditions

    NASA Astrophysics Data System (ADS)

    Mahmudul, H. M.; Hagos, Ftwi. Y.; A, M. Mukhtar N.; Mamat, Rizalman; Abdullah, A. Adam

    2018-03-01

    Biodiesel is a promising alternative fuel to run the automotive engine. However, its blends have not been properly investigated during idling as it is the main problem to run the vehicles in a big city. The purpose of this study is to evaluate the impact of alcohol additives such as butanol and ethanol on combustion parameters under idling conditions when a single cylinder diesel engine operates with diesel, diesel-biodiesel blends, and diesel biodiesel-alcohol blends. The engine combustion parameters such as peak pressure, heat release rate and ignition delay were computed. This investigation has revealed that alcohol blends with diesel and biodiesel, BU20 blend yield higher maximum peak cylinder pressure than diesel. B5 blend was found with the lowest energy release among all. B20 was slightly lower than diesel. BU20 blend was seen with the highest peak energy release where E20 blend was found advance than diesel. Among all, the blends alcohol component revealed shorter ignition delay. B5 and B20 blends were influenced by biodiesel interference and the burning fraction were found slightly slower than conventional diesel where BU20 and E20 blends was found slightly faster than diesel So, based on the result, it can be said that among the alcohol blends butanol and ethanol can be promising alternative at idling conditions and can be used without any engine modifications.

  16. Quantitative Surface Emissivity and Temperature Measurements of a Burning Solid Fuel Accompanied by Soot Formation

    NASA Technical Reports Server (NTRS)

    Piltch, Nancy D.; Pettegrew, Richard D.; Ferkul, Paul; Sacksteder, K. (Technical Monitor)

    2001-01-01

    Surface radiometry is an established technique for noncontact temperature measurement of solids. We adapt this technique to the study of solid surface combustion where the solid fuel undergoes physical and chemical changes as pyrolysis proceeds, and additionally may produce soot. The physical and chemical changes alter the fuel surface emissivity, and soot contributes to the infrared signature in the same spectral band as the signal of interest. We have developed a measurement that isolates the fuel's surface emissions in the presence of soot, and determine the surface emissivity as a function of temperature. A commercially available infrared camera images the two-dimensional surface of ashless filter paper burning in concurrent flow. The camera is sensitive in the 2 to 5 gm band, but spectrally filtered to reduce the interference from hot gas phase combustion products. Results show a strong functional dependence of emissivity on temperature, attributed to the combined effects of thermal and oxidative processes. Using the measured emissivity, radiance measurements from several burning samples were corrected for the presence of soot and for changes in emissivity, to yield quantitative surface temperature measurements. Ultimately the results will be used to develop a full-field, non-contact temperature measurement that will be used in spacebased combustion investigations.

  17. Performance Evaluation of Diesel Engine with Preheated Bio Diesel with Additives

    NASA Astrophysics Data System (ADS)

    Ram Vajja, Sai; Murali, R. B. V.

    2016-09-01

    This paper mainly reviews about the usage of preheated bio diesel added with 0.5% Etchant as an alternative fuel and evaluates its performance for various blends with different loads. Bio diesel is added with Etchant for rapid combustion as for the bio diesel, the cetane number is high that results in shorter delay of ignition and the mixture is preheated to raise its temperature to improve the combustion process. Analysis of the parameters required to define the combustion characteristics such as IP, BP, ηbth, ηm, ISFC, BSFC, IMEP, MFC, Exhaust Gas Temperature, Heat Release and heat balance is necessary as these values are significant to assess the performance of engine and its emissions of preheated bio diesel.

  18. Structure and Soot Properties of Nonbuoyant Ethylene/Air Laminar Jet Diffusion Flames. Appendix E; Repr. from AIAA Journal, v. 36 p 1346-1360

    NASA Technical Reports Server (NTRS)

    Urban, D. L.; Yuan, Z.-G.; Sunderland, P. B.; Linteris, G. T.; Voss, J. E.; Lin, K.-C.; Dai, Z.; Sun, K.; Faeth, G. M.; Ross, Howard D. (Technical Monitor)

    2001-01-01

    The structure and soot properties of round, soot-emitting, nonbuoyant, laminar jet diffusion flames are described, based on long-duration (175-230-s) experiments at microgravity carried out on orbit in the Space Shuttle Columbia. Experimental conditions included ethylene-fueled flames burning in still air at nominal pressures of 50 and 100 kPa and an ambient temperature of 300 K with luminous flame lengths of 49-64 mm Measurements included luminous flame shapes using color video imaging soot concentration (volume fraction) distributions using deconvoluted laser extinction imaging, soot temperature distributions using deconvoluted multiline emission imaging, gas temperature distributions at fuel-lean (plume) conditions using thermocouple probes, soot structure distributions using thermophoretic sampling and analysis by transmission electron microscopy, and flame radiation using a radiometer.The present flames were larger, and emitted soot more readily, than comparable flames observed during ground-based microgravity experiments due to closer approach to steady conditions resulting from the longer test times and the reduced gravitational disturbances of the space-based experiments.

  19. EFFECT OF SOOT AND COPPER COMBUSTOR DEPOSITS ON DIOXIN EMISSIONS

    EPA Science Inventory

    An experimental study was conducted to investigate the effects of residual soot and copper combustor deposits on the formation of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) during the combustion of a chlorinated waste. In a bench-scale set...

  20. Emission Performance of Low Cetane Naphtha as Drop-In Fuel on a Multi-Cylinder Heavy-Duty Diesel Engine and Aftertreatment System

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    LeePhD, John; TzanetakisPhD, Tom; Travers, Michael

    With higher volatility and longer ignition delay characteristics than typical diesel fuel, low cetane naphtha fuel has been shown to promote partially premixed combustion and produce lower soot for improved fuel economy. In this study, emission performance of low cetane, low octane naphtha (CN 35, RON 60) as a drop-in fuel was examined on a MY13 Cummins ISX15 6-cylinder heavy-duty on-highway truck engine and aftertreatment system. Using the production hardware and development calibrations, both the engine-out and tailpipe emissions of naphtha and ultra-low sulfur diesel (ULSD) fuels were examined during the EPA s heavy-duty emission testing cycles. Without any modificationmore » to the calibrations, the tailpipe emissions were comparable when using naphtha or ULSD on the heavy duty Federal Test Procedure (FTP) and ramped modal cycle (RMC) test cycles. Overall lower CO2 emissions and fuel consumption were also measured for naphtha due in part to its higher heating value and higher hydrogen to carbon ratio. Engine-out and tailpipe NOx emissions were lower for naphtha fuel at the same catalyst conversion levels and measured particulate matter (PM) emissions were also lower when using naphtha due to its higher volatility and lower aromatic content compared to ULSD. To help assess the potential impact on diesel particulate filter design and operation, engine-out PM samples were collected and characterized at the B50 operating point. A significant reduction in elemental carbon (EC) within the particulate emissions was found when using naphtha compared to ULSD.« less