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1

A simple one-step chemistry model for partially premixed hydrocarbon combustion  

SciTech Connect

This work explores the applicability of one-step irreversible Arrhenius kinetics with unity reaction order to the numerical description of partially premixed hydrocarbon combustion. Computations of planar premixed flames are used in the selection of the three model parameters: the heat of reaction q, the activation temperature T{sub a}, and the preexponential factor B. It is seen that changes in q with equivalence ratio f need to be introduced in fuel-rich combustion to describe the effect of partial fuel oxidation on the amount of heat released, leading to a universal linear variation q(f) for f>1 for all hydrocarbons. The model also employs a variable activation temperature T{sub a}(f) to mimic changes in the underlying chemistry in rich and very lean flames. The resulting chemistry description is able to reproduce propagation velocities of diluted and undiluted flames accurately over the whole flammability limit. Furthermore, computations of methane-air counterflow diffusion flames are used to test the proposed chemistry under nonpremixed conditions. The model not only predicts the critical strain rate at extinction accurately but also gives near-extinction flames with oxygen leakage, thereby overcoming known predictive limitations of one-step Arrhenius kinetics. (author)

Fernandez-Tarrazo, Eduardo [Instituto Nacional de Tecnica Aeroespacial, Madrid (Spain); Sanchez, Antonio L. [Area de Mecanica de Fluidos, Universidad Carlos III de Madrid, Leganes 28911 (Spain); Linan, Amable [ETSI Aeronauticos, Pl. Cardenal Cisneros 3, Madrid 28040 (Spain); Williams, Forman A. [Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA 92093-0411 (United States)

2006-10-15

2

Hydrocarbon Fouling of SCR during PCCI combustion  

SciTech Connect

The combination of advanced combustion with advanced selective catalytic reduction (SCR) catalyst formulations was studied in the work presented here to determine the impact of the unique hydrocarbon (HC) emissions from premixed charge compression ignition (PCCI) combustion on SCR performance. Catalyst core samples cut from full size commercial Fe- and Cu-zeolite SCR catalysts were exposed to a slipstream of raw engine exhaust from a 1.9-liter 4-cylinder diesel engine operating in conventional and PCCI combustion modes. The zeolites which form the basis of these catalysts are different with the Cu-based catalyst made on a chabazite zeolite which las smaller pore structures relative to the Fe-based catalyst. Subsequent to exposure, bench flow reactor characterization of performance and hydrocarbon release and oxidation enabled evaluation of overall impacts from the engine exhaust. The Fe-zeolite NOX conversion efficiency was significantly degraded, especially at low temperatures (<250 C), after the catalyst was exposed to the raw engine exhaust. The degradation of the Fe-zeolite performance was similar for both combustion modes. The Cu-zeolite showed better tolerance to HC fouling at low temperatures compared to the Fe-zeolite but PCCI exhaust had a more significant impact than the exhaust from conventional combustion on the NOX conversion efficiency. Furthermore, chemical analysis of the hydrocarbons trapped on the SCR cores was conducted to better determine chemistry specific effects.

Prikhodko, Vitaly Y [ORNL; Pihl, Josh A [ORNL; Lewis Sr, Samuel Arthur [ORNL; Parks, II, James E [ORNL

2012-01-01

3

Combustion Chemistry of Solid Propellants.  

National Technical Information Service (NTIS)

Several studies are described of the chemistry of solid propellant combustion which employed a fast-scanning optical spectrometer. Expanded abstracts are presented for four of the studies which were previously reported. One study of the ignition of compos...

A. D. Baer N. W. Ryan

1974-01-01

4

Coal combustion chemistry correlation aspects  

SciTech Connect

This book provides fundamental guidelines to reducing the combustion problems that inorganic impurity compounds cause in coal-fired electricity-generating plants. The compounds treated are those of eight major-abundance metal and semimetal elements - silcon, aluminum, iron, calcium, potassium, magnesium, titanium, and sodium. The book employs a combustion chemistry approach, together with a methodology that relates empirical correlations to the effects of inorganic impurity compounds on oxidation-combustion that may occur prior to ignition, at ignition, during heat-up to flame temperatures, or at flame temperatures. Why basic oxide constituents have higher chemical reactivities during coal combustion than acidic oxide chemical reactivities is shown in the introductory chapter. Other discussions cover the chemistry and coal-science backgrounds that relate to oxide constituents of the eight major-abundance elements. The book concludes with sets of empirical correlations.

Badin, E.J.

1984-01-01

5

Coal combustion chemistry correlation aspects  

Microsoft Academic Search

This book provides fundamental guidelines to reducing the combustion problems that inorganic impurity compounds cause in coal-fired electricity-generating plants. The compounds treated are those of eight major-abundance metal and semimetal elements - silcon, aluminum, iron, calcium, potassium, magnesium, titanium, and sodium. The book employs a combustion chemistry approach, together with a methodology that relates empirical correlations to the effects of

Badin

1984-01-01

6

Odorization of combustible hydrocarbon gases  

SciTech Connect

Described is a warning agent for the odorization of gaseous hydrocarbon fuels based on mixtures of at least one of the compounds, 2-methooxy-3-isobutyl pyrazine and 4-methyl-4-mercapto-2-pentanone with a monomercaptan or a sulfide.

Yoshida, T.; Katz, I.; Warren, C. B.; Wiener, C.

1984-12-11

7

Combustion chemistry of propane: A case study of detailed reaction mechanism optimization  

Microsoft Academic Search

Detailed chemical reaction mechanisms describing hydrocarbon combustion chemistry are conceptually structured in a hierarchical manner with H2 and CO chemistry at the base, supplemented as needed by elementary reactions of larger chemical species. While this structure gives a logical organization to com- bustion chemistry, the degree to which this organization reflects actual reactive fluxes in flames is not known. Moreover,

Zhiwei Qin; Vitali V. Lissianski; Huixing Yang; William C. Gardiner; Scott G. Davis; Hai Wang

2000-01-01

8

Global reaction schemes for hydrocarbon combustion  

Microsoft Academic Search

Global reaction schemes for the combustion of alkane hydrocarbons up to butane in mixtures with air in premixed and diffusion flames have been derived using analysis of flame structures. The schemes include two competing fuel breakdown reactions, and equilibrium assumptions have been used to derive initial estimates of the forms of the rate expressions. The deduced four-step reaction mechanism is

W. P. Jones; R. P. Lindstedt

1988-01-01

9

Chemistry in Titan's Hydrocarbon Seas  

NASA Astrophysics Data System (ADS)

Multiple lines of evidence from the Cassini-Huygens mission demonstrate that Titan's large lakes and seas are composed of liquid ethane and methane. In addition to the aforementioned constituents, recent work on solubility indicates that propane, dissolved acetylene and nitriles will be significant components (Cordier, D. et al., ApJ v. 707, 128, 2009). Here we make a preliminary examination of the kinds of chemistry that might occur in such a multicomponent organic solution at temperatures of 90 K subject to various energy sources including modulations of solar heating on seasonal and longer timescales (Aharonson et al., Nature Geoscience v. 2 851, 2009), cosmic rays, and (more speculatively) regional cryovolcanism. It is known that carbon cations (C+) can form in methane, and thus these cations might be found in the liquid methane and ethane comprising the polar seas of Titan. As a result, the methane would become a weak protic solvent, which opens the possibility of methane and its sister alkanes participating in more vigorous organic reactions and erosional processes with the surrounding bedrock than previously thought. We apply these considerations to several problems: (a) We calculate rates of chemical erosion of geological features surrounding the large seas, assuming the surrounding country rock to be (i) water, (ii) water-ammonia, (iii) solid organics. (b) We recompute the solubility of minor polar constituents in the seas, which should be enhanced thanks to the protic behavior of the methane. (c) Non-aqueous biochemistries in hydrocarbon liquids such as those proposed by Benner et al. (Current Opinions in Chem. Bio. v. 8, 672-689) will be aided by the potential for enhanced polarity of the liquid. This work was supported by the NASA Astrobiology Institute, and the program "Incentivazione alla mobilita' di studiosi straineri e italiani residenti all'estero."

Lunine, Jonathan I.; Jacobs, Norman; Cordier, Daniel; Mousis, Olivier

2010-05-01

10

Theory and modeling in combustion chemistry.  

National Technical Information Service (NTIS)

This paper discusses four important problems in combustion chemistry. In each case, resolution of the problem focuses on a single elementary reaction. Theoretical analysis of this reaction is discussed in some depth, with emphasis on its unusual features....

J. A. Miller

1996-01-01

11

Detailed and reduced chemical-kinetic descriptions for hydrocarbon combustion  

NASA Astrophysics Data System (ADS)

Numerical and theoretical studies of autoignition processes of fuels such as propane are in need of realistic simplified chemical-kinetic descriptions that retain the essential features of the detailed descriptions. These descriptions should be computationally feasible and cost-effective. Such descriptions are useful for investigating ignition processes that occur, for example, in homogeneous-charge compression-ignition engines, for studying the structures and dynamics of detonations and in fields such as multi-dimensional Computational Fluid Dynamics (CFD). Reduced chemistry has previously been developed successfully for a number of other hydrocarbon fuels, however, propane has not been considered in this manner. This work focuses on the fuels of propane, as well propene, allene and propyne, for several reasons. The ignition properties of propane resemble those of other higher hydrocarbons but are different from those of the lower hydrocarbons (e.g. ethylene and acetylene). Propane, therefore, may be the smallest hydrocarbon that is representative of higher hydrocarbons in ignition and detonation processes. Since the overall activation energy and ignition times for propane are similar to those of other higher hydrocarbons, including liquid fuels that are suitable for many applications, propane has been used as a model fuel for several numerical and experimental studies. The reason for studying elementary chemistry of propene and C3H4 (allene or propyne) is that during the combustion process, propane breaks down to propene and C3H4 before proceeding to products. Similarly, propene combustion includes C3H4 chemistry. In studying propane combustion, it is therefore necessary to understand the underlying combustion chemistry of propene as well as C3H 4. The first part of this thesis focuses on obtaining and testing a detailed chemical-kinetic description for autoignition of propane, propene and C 3H4, by comparing predictions obtained with this detailed mechanism against numerous experimental data available from shock-tube studies and flame-speed measurements. To keep the detailed mechanism small, attention is restricted to pressures below about 100 atm, temperatures above about 1000 K and equivalence ratios less than about 3. Based on this detailed chemistry description, short (or skeletal) mechanisms are then obtained for each of the three fuels by eliminating reactions that are unimportant for the autoignition process under conditions presented above. This was achieved by utilizing tools such as sensitivity and reaction pathway analyses. Two distinct methodologies were then used in order to obtain a reduced mechanism for autoignition from the short mechanisms. A Systematic Reduction approach is first taken that involves introducing steady-state approximations to as many species as analytically possible. To avoid resorting to numerical methods, the analysis for obtaining ignition times for heptane, presented by Peters and co-workers is followed in order to obtain a rough estimate for an expression of propane ignition time. The results from this expression are then compared to the ignition times obtained computationally with the detailed mechanism. The second method is an Empirical Approach in which chemistry is not derived formally, but rather postulated empirically on the basis of experimental, computational and theoretical observations. As a result, generalized reduced mechanisms are proposed for autoignition of propane, propene and C3H 4. Expressions for ignition times obtained via this empirical approach are compared to the computational results obtained from the detailed mechanism.

Petrova, Maria V.

12

Atmospheric hydrocarbon chemistry in central Texas  

NASA Astrophysics Data System (ADS)

Hydrocarbon chemistry plays a central role in the determination of the concentrations of ozone, nitrogen oxides and particulate matter in the ambient troposphere. Many years of research have led to a preliminary understanding of the complex chemistry of the thousands of hydrocarbons that are emitted into the atmosphere by biogenic and anthropogenic sources. However, much remains unresolved. This thesis will address several of the unresolved issues in the complex hydrocarbon chemistry that occurs in urban atmospheres. The first portion of this thesis reports atmospheric concentrations of hydrocarbons in Central Texas. These concentrations were compared to hydrocarbon concentrations observed in other urban areas. Probable sources of atmospheric hydrocarbons within Central Texas were identified from spatially resolved hydrocarbon emission inventories. These measurements and identified probable sources suggest the second major portion of the thesis: an analysis of one of the most commonly used source resolution tools, the Chemical Mass Balance (CMB) method. CMB uses linear algebra to identify the sources and source strengths of hydrocarbons in ambient air samples. However, there are several assumptions made by the model to accomplish this task, and these assumptions are believed to impair the model's accuracy. Therefore, the second portion of the thesis characterized the uncertainties associated with the accuracy of CMB, particularly when it was applied to ambient data from Southeast Texas. A multistage box model was constructed to simulate ambient hydrocarbon concentrations in Houston. The box model simulated the inputs of hydrocarbon sources into a hypothetical air mass, while accounting for the unique reactivities of each of the modeled hydrocarbons. The CMB tool was then applied to the data generated by the box model and used to estimate source strengths. The source strengths estimated by CMB were compared to the original inputs to the model. The results indicated that source contribution estimates (SCEs) from CMB were not accurate predictions of the true source strengths in Southeast Texas when reasonable uncertainties were introduced into the source profiles and the distribution of sources. Additional data on source profiles, and possibly the identification of new molecular tracers of specific sources, are needed to improve source resolution.

Wittig, Ann Elizabeth

13

Effect of Hydrogen Enriched Hydrocarbon Combustion on Emissions and Performance  

Microsoft Academic Search

The principle of this mode of combustion is to add a percentage of hydrogen gas to the combustion reactions of either compression or spark ignition engines. The addition of hydrogen has been shown to decrease the formation of NOx, CO and unburned hydrocarbons. Studies have shown that added hydrogen in percentages as low as 5-10% percent of the hydrocarbon fuel

Jacob Wall

14

Sulphur Chemistry in Combustion II  

Microsoft Academic Search

\\u000a Several options are available to control the emission of SO2 from combustion processes. One possibility is to use a cleaner technology, i.e. fuel switching from oil and coal to natural\\u000a gas or biomass, or to desulphurize coal and oil, [1]. Another possibility is to change to a different technology for power production, such as sun, wind or nuclear power. However,

J. E. Johnsson; S. Kiil

15

Vibrational Relaxation in the Products of Hydrocarbon Fuel Combustion.  

National Technical Information Service (NTIS)

The oscillating relaxation time in the combustion products of a hydrocarbon fuel as it flows from a nozzle under supersonic flow conditions was calcualted. For certain components the duration of the oscillating relaxation is comparable to the characterist...

V. N. Arkhipov

1972-01-01

16

Filtration Combustion in Hydrocarbon Desorption from a Porous Medium  

Microsoft Academic Search

We have investigated theoretically and experimentally the process of filtration combustion with hydrocarbon desorption from a porous skeleton realized, in particular, in heat cleaning of porous media out of residues of organic impurities. The problem on the wave of such a combustion in a system with three phases — gaseous, liquid, and inert solid — has been solved analytically. The

S. I. Fut'ko; K. V. Dobrego; E. S. Shmelev; A. V. Suvorov; S. A. Zhdanok

2003-01-01

17

Theory and modeling in combustion chemistry  

SciTech Connect

This paper discusses four important problems in combustion chemistry. In each case, resolution of the problem focuses on a single elementary reaction. Theoretical analysis of this reaction is discussed in some depth, with emphasis on its unusual features. The four combustion problems and their elementary reactions are: (1) Burning velocities, extinction limits, and flammability limits: H+O{sub 2}{leftrightarrow}OH+O, (2) Prompt NO: CH+N{sub 2}{leftrightarrow}HCN+N, (3) the Thermal De-NO{sub x} Process: NH{sub 2}+NO{leftrightarrow}products, and (4) ``Ring`` formation in flames of aliphatic fuels and the importance of resonantly stabilized free radicals: C{sub 3}H{sub 3}{leftrightarrow}products.

Miller, J.A.

1996-10-01

18

Recent applications of synchrotron VUV photoionization mass spectrometry: insight into combustion chemistry.  

PubMed

Combustion is one of the earliest developed human technologies and remains our primary source of energy, yet it embodies a complex suite of physical and chemical processes that are inadequately understood. Combustion chemistry involves both chemical thermodynamics and chemical kinetics, and experimental advances mostly depend on the development of combustion diagnostics, which effectively serve as the foundation of theoretical progress. The major objective of combustion diagnostics is to provide comprehensive product identification and concentration information of a flame species, which can be used to develop kinetic models for the simulation of practical combustion. However, conventional combustion diagnostic methods face difficult challenges in distinguishing isomeric species, detecting reactive radicals, obtaining real-time measurements, and so forth. Therefore, for deeper insight into combustion chemistry, a diagnostic method with high detection sensitivity, isomeric selectivity, and radical detectability is required. In this Account, we report recent applications of synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS) in various areas of combustion chemistry research. The wide tunability of synchrotron photon energy can facilitate the selective identification of isomeric intermediates and the near-threshold detection of radicals (thus avoiding fragmentation interference). Moreover, the convenient combination of SVUV-PIMS with various laboratory-based combustion approaches demonstrates its universality in combustion studies. Recent experimental achievements have demonstrated the successful applications of this technique in premixed flames, pyrolysis in flow reactors, coflow diffusion flames, catalytic oxidation, plasma diagnostics, and analysis of polycyclic aromatic hydrocarbons (PAHs) and soot. More applications of SVUV-PIMS are expected in the near future, not only in combustion studies, but also in other research topics of chemistry such as analytical chemistry, photochemistry, biochemistry, and the like. In all applications, combustion intermediates, including isomers and radicals, can be distinguished unambiguously, extending our knowledge of intermediate pools and providing more precise targets for quantum chemical calculations of significant reaction channels. The observed mass range covers both small and large combustion products, such as PAHs with two to five carbonic rings. Such analyses present clues toward understanding the molecular growth process from fuel to PAHs and, consequently, soot in fuel-rich hydrocarbon flames. Furthermore, quantitative analyses of chemical structure are available in most applications. For example, one can acquire concentration profiles of flame species versus position in premixed and diffusion flames or versus temperature in pyrolysis and catalytic oxidation. The objectives of validating current kinetic models and developing new kinetic models are thus well served with SVUV-PIMS as an analytical tool in combustion research. PMID:19705821

Li, Yuyang; Qi, Fei

2010-01-19

19

Combustion Kinetics and Emission Characteristics of Polycyclic Aromatic Hydrocarbons from Polylactic Acid Combustion  

Microsoft Academic Search

This study investigates the combustion kinetics and emission factors of 16 U.S. Environmental Protection Agency priority polycyclic aromatic hydrocarbons (PAHs) in polylactic acid (PLA) combustion. Experimentally, two reactions are involved in the PLA combustion process that potentially result in the release of lactide, acetaldehyde, and n-hexaldehyde. The products may continuously be oxidized to form carbon dioxide (CO2) and some PAHs

Yi-Chi Chien; Chenju Liang; Shou-Heng Liu; Shu-Hua Yang; Krzysztof Gaska; Lingjuan Wang; Edgar Oviedo-Rondon; John Small; Zifei Liu; Brian Sheldon; Gerald Havenstein; C. Williams; Di Tian; Daniel Cohan; Sergey Napelenok; Michelle Bergin; Yongtao Hu; Michael Chang; Armistead Russell; Ye Xu; Guohe Huang; Xiaosheng Qin; Kuo-Pin Yu; Grace Lee; Guo-Hao Huang; Prabhakar Sharma; Tjalfe Poulsen; William Vizuete; Leiran Biton; Harvey Jeffries; Evan Couzo; Maciej Kryza; Malgorzata Werner; Marek Blas; Anthony Dore; Mieczyslaw Sobik; Daniel Olsen; Morgan Kohls; Gregg Arney; Kaushlendra Singh; L. Risse; K. C. Das; John Worley; Sidney Thompson; Bryan Comer; James Corbett; J. Hawker; Karl Korfmacher; Earl Lee; Chris Prokop; James Winebrake

2010-01-01

20

Hydrocarbon Combustion in a Fluidised Bed.  

National Technical Information Service (NTIS)

The advantages of flameless combustion of premixed air and fuel in presence of solids, preferably when the solids are in a fluidized state, with or without catalytic effect are discussed in the report. An experimental fluidized bed reactor for high temper...

P. Haribabu

1978-01-01

21

Combustion kinetics and emission characteristics of polycyclic aromatic hydrocarbons from polylactic acid combustion.  

PubMed

This study investigates the combustion kinetics and emission factors of 16 U.S. Environmental Protection Agency priority polycyclic aromatic hydrocarbons (PAHs) in polylactic acid (PLA) combustion. Experimentally, two reactions are involved in the PLA combustion process that potentially result in the release of lactide, acetaldehyde, and n-hexaldehyde. The products may continuously be oxidized to form carbon dioxide (CO2) and some PAHs produced because of incomplete combustion. The analytical results indicate that the emission factors for PAHs are in the range of not detectable to 98.04 microg/g. The emission factors are much lower than those of poly(ethylene terephalate) (PET) and other combustion of plastics. Results from this work suggest that combustion is a good choice for waste PLA disposal. PMID:20681432

Chien, Yi-Chi; Liang, Chenju; Liu, Shou-Heng; Yang, Shu-Hua

2010-07-01

22

Chemical Kinetics of Hydrocarbon Ignition in Practical Combustion Systems  

SciTech Connect

Chemical kinetic factors of hydrocarbon oxidation are examined in a variety of ignition problems. Ignition is related to the presence of a dominant chain branching reaction mechanism that can drive a chemical system to completion in a very short period of time. Ignition in laboratory environments is studied for problems including shock tubes and rapid compression machines. Modeling of the laboratory systems are used to develop kinetic models that can be used to analyze ignition in practical systems. Two major chain branching regimes are identified, one consisting of high temperature ignition with a chain branching reaction mechanism based on the reaction between atomic hydrogen with molecular oxygen, and the second based on an intermediate temperature thermal decomposition of hydrogen peroxide. Kinetic models are then used to describe ignition in practical combustion environments, including detonations and pulse combustors for high temperature ignition, and engine knock and diesel ignition for intermediate temperature ignition. The final example of ignition in a practical environment is homogeneous charge, compression ignition (HCCI) which is shown to be a problem dominated by the kinetics intermediate temperature hydrocarbon ignition. Model results show why high hydrocarbon and CO emissions are inevitable in HCCI combustion. The conclusion of this study is that the kinetics of hydrocarbon ignition are actually quite simple, since only one or two elementary reactions are dominant. However, there are many combustion factors that can influence these two major reactions, and these are the features that vary from one practical system to another.

Westbrook, C.K.

2000-07-07

23

Acceleration of the chemistry solver for modeling DI engine combustion using dynamic adaptive chemistry (DAC) schemes  

Microsoft Academic Search

Acceleration of the chemistry solver for engine combustion is of much interest due to the fact that in practical engine simulations extensive computational time is spent solving the fuel oxidation and emission formation chemistry. A dynamic adaptive chemistry (DAC) scheme based on a directed relation graph error propagation (DRGEP) method has been applied to study homogeneous charge compression ignition (HCCI)

Yu Shi; Long Liang; Hai-Wen Ge; Rolf D. Reitz

2010-01-01

24

Atmospheric chemistry of gas-phase polycyclic aromatic hydrocarbons: formation of atmospheric mutagens.  

PubMed Central

The atmospheric chemistry of the 2- to 4-ring polycyclic aromatic hydrocarbons (PAH), which exist mainly in the gas phase in the atmosphere, is discussed. The dominant loss process for the gas-phase PAH is by reaction with the hydroxyl radical, resulting in calculated lifetimes in the atmosphere of generally less than one day. The hydroxyl (OH) radical-initiated reactions and nitrate (NO3) radical-initiated reactions often lead to the formation of mutagenic nitro-PAH and other nitropolycyclic aromatic compounds, including nitrodibenzopyranones. These atmospheric reactions have a significant effect on ambient mutagenic activity, indicating that health risk assessments of combustion emissions should include atmospheric transformation products.

Atkinson, R; Arey, J

1994-01-01

25

Explosion-induced combustion of hydrocarbon clouds in a chamber  

SciTech Connect

The interaction of the detonation of a solid HE-charge with a non-premixed cloud of hydro-carbon fuel in a chamber was studied in laboratory experiments. Soap bubbles filled with a flammable gas were subjected to the blast wave created by the detonation of PETN-charges (0.2 g < mass < 0.5 g). The dynamics of the combustion system were investigated by means of high-speed photography and measurement of the quasi-static chamber pressure.

Neuwald, P; Reichenbach, H; Kuhl, A L

2001-02-06

26

Autoxidation of Hydrocarbons: From Chemistry to Catalysis  

Microsoft Academic Search

This contribution summarizes our recent efforts to unravel the radical chemistry of autoxidations. Abstraction of the weakly\\u000a bonded ?H-atom of the primary hydroperoxide product by chain carrying peroxyl radicals is identified as the source of major\\u000a end products such as alcohol and ketone\\/aldehyde. In the case of cyclohexane autoxidation, this reaction is even responsible\\u000a for the majority of ring-opened by-products.

Ive Hermans; Jozef Peeters; Pierre A. Jacobs

2008-01-01

27

Sodium and sulfur chemistry in combustion gases.  

National Technical Information Service (NTIS)

In the present work the chemistry of sodium and sulfur in flue gas are examined with respect to deposit formation and corrosion effects. Measurements, industrial as well as laboratory, constitute the basis of the treatment. In the theoretical consideratio...

R. Backman

1989-01-01

28

Applications of sensitivity analysis to combustion chemistry  

Microsoft Academic Search

Combustion chemical models usually contain several hundred or thousand kinetic rate parameters. Most simulation packages calculate local concentration sensitivities, but it is frequently not easy to extract meaningful information from large sensitivity matrices. Principal component analysis is a simple post-processing technique that summarizes sensitivity information and also reveals the effect of simultaneously changing parameters.A new program package, called KINALC, has

Tamás Turányi

1997-01-01

29

Global simulation of tropospheric O3-NOx-hydrocarbon chemistry  

Microsoft Academic Search

Abstract.We describe a global three-dimensional model for tropospheric O 3-NOx-hydrocar- bon chemistry with synoptic-scale resolution. A suite of 15 chemical tracers, including O 3, NOx, PAN, HNO3, CO, H2O2, and various hydrocarbons, is simulated in the model. For com- putational expediency, chemical production and loss of tracers are parameterized as polynomial functions to fit the results of a detailed O

Y. Wang; D. J. Jacob; J. A. Logan

1998-01-01

30

Novel applications of light hydrocarbons chemistry in petroleum exploration  

SciTech Connect

The light hydrocarbons in petroleum are products of a kerogen-specific catalytic process. The catalysts are believed to be the transition metals entrained in kerogen. The process is controlled by the metals in the active sites and the kerogenous organic structures surrounding the active sites. Different catalytic sites are suggested to yield distinct distributions of light hydrocarbons. The author recognizes three dominant (primary) distributions, with all other distributions adequately represented by some linear combination of the three primary distributions. Three catalytic sites, therefore, can be associated with the generation of light hydrocarbons. He introduces a simple and inexpensive procedure using cross plots of various product ratios to correlate oils and source rocks. It has proven to be a remarkably articulate and powerful tool for deconvoluting diverse oils into genetic groups. The light hydrocarbons are also indicators of oil-generation temperature and other physical parameters associated with oil generation. The analysis of light hydrocarbons from this perspective is new. It provides the exploration geochemist with a novel technique for gaining insight into the fundamental chemistry of petroleum generation.

Mango, F.D. (Shell Development Co., Houston, TX (United States))

1991-03-01

31

A filtered tabulated chemistry model for LES of premixed combustion  

SciTech Connect

A new modeling strategy called F-TACLES (Filtered Tabulated Chemistry for Large Eddy Simulation) is developed to introduce tabulated chemistry methods in Large Eddy Simulation (LES) of turbulent premixed combustion. The objective is to recover the correct laminar flame propagation speed of the filtered flame front when subgrid scale turbulence vanishes as LES should tend toward Direct Numerical Simulation (DNS). The filtered flame structure is mapped using 1-D filtered laminar premixed flames. Closure of the filtered progress variable and the energy balance equations are carefully addressed in a fully compressible formulation. The methodology is first applied to 1-D filtered laminar flames, showing the ability of the model to recover the laminar flame speed and the correct chemical structure when the flame wrinkling is completely resolved. The model is then extended to turbulent combustion regimes by including subgrid scale wrinkling effects in the flame front propagation. Finally, preliminary tests of LES in a 3-D turbulent premixed flame are performed. (author)

Fiorina, B.; Auzillon, P.; Darabiha, N.; Gicquel, O.; Veynante, D. [EM2C - CNRS, Ecole Centrale Paris, 92295 Chatenay Malabry (France); Vicquelin, R. [EM2C - CNRS, Ecole Centrale Paris, 92295 Chatenay Malabry (France); GDF SUEZ, Pole CHENE, Centre de Recherche et d'Innovation Gaz et Energies Nouvelles, 93211 Saint-Denis la Plaine (France)

2010-03-15

32

Premixed hydrocarbon stagnation flames : experiments and simulations to validate combustion chemical-kinetic models  

NASA Astrophysics Data System (ADS)

A methodology based on the comparison of flame simulations relying on reacting flow models with experiment is applied to C1-C3 stagnation flames. The work reported targets the assessment and validation of the modeled reactions and reaction rates relevant to (C1-C3)-flame propagation in several detailed combustion kinetic models. A concensus does not, as yet, exist on the modeling of the reasonably well-understood oxidation of C1-C2 flames, and a better knowledge of C3 hydrocarbon combustion chemistry is required before attempting to bridge the gap between the oxidation of C1-C2 hydrocarbons and the more complex chemistry of heavier hydrocarbons in a single kinetic model. Simultaneous measurements of velocity and CH-radical profiles were performed in atmospheric propane(C3H8)- and propylene(C3H6)-air laminar premixed stagnation flames stabilized in a jet-wall configuration. These nearly-flat flames can be modeled by one-dimensional simulations, providing a means to validate kinetic models. Experimental data for these C3 flames and similar experimental data for atmospheric methane(CH4)-, ethane(C2H6)-, and ethylene(C2H4)-air flames are compared to numerical simulations performed with a one-dimensional hydrodynamic model, a multi-component transport formulation including thermal diffusion, and different detailed-chemistry models, in order to assess the adequacy of the models employed. A novel continuation technique between kinetic models was developed and applied successfully to obtain solutions with the less-robust models. The 2005/12 and 2005/10 releases of the San Diego mechanism are found to have the best overall performance in C3H8 and C3H6 flames, and in CH4, C2H6, and C2H4 flames, respectively. Flame position provides a good surrogate for flame speed in stagnation-flow stabilized flames. The logarithmic sensitivities of the simulated flame locations to variations in the kinetic rates are calculated via the "brute-force" method for fifteen representative flames covering the five fuels under study and the very lean, stoichiometric, and very rich burning regimes, in order to identify the most-important reactions for each flame investigated. The rates of reactions identified in this manner are compared between the different kinetic models. Several reaction-rate differences are thus identified that are likely responsible for the variance in flame-position (or flame-speed) predictions in C1-C2 flames.

Benezech, Laurent Jean-Michel

33

Chemistry of polycyclic aromatic hydrocarbons formation from phenyl radical pyrolysis and reaction of phenyl and acetylene.  

PubMed

An experimental investigation of phenyl radical pyrolysis and the phenyl radical + acetylene reaction has been performed to clarify the role of different reaction mechanisms involved in the formation and growth of polycyclic aromatic hydrocarbons (PAHs) serving as precursors for soot formation. Experiments were conducted using GC/GC-MS diagnostics coupled to the high-pressure single-pulse shock tube present at the University of Illinois at Chicago. For the first time, comprehensive speciation of the major stable products, including small hydrocarbons and large PAH intermediates, was obtained over a wide range of pressures (25-60 atm) and temperatures (900-1800 K) which encompass the typical conditions in modern combustion devices. The experimental results were used to validate a comprehensive chemical kinetic model which provides relevant information on the chemistry associated with the formation of PAH compounds. In particular, the modeling results indicate that the o-benzyne chemistry is a key factor in the formation of multi-ring intermediates in phenyl radical pyrolysis. On the other hand, the PAHs from the phenyl + acetylene reaction are formed mainly through recombination between single-ring aromatics and through the hydrogen abstraction/acetylene addition mechanism. Polymerization is the common dominant process at high temperature conditions. PMID:22339468

Comandini, A; Malewicki, T; Brezinsky, K

2012-03-02

34

DIESEL OXIDATION CATALYST CONTROL OF HYDROCARBON AEROSOLS FROM REACTIVITY CONTROLLED COMPRESSION IGNITION COMBUSTION  

SciTech Connect

Reactivity Controlled Compression Ignition (RCCI) is a novel combustion process that utilizes two fuels with different reactivity to stage and control combustion and enable homogeneous combustion. The technique has been proven experimentally in previous work with diesel and gasoline fuels; low NOx emissions and high efficiencies were observed from RCCI in comparison to conventional combustion. In previous studies on a multi-cylinder engine, particulate matter (PM) emission measurements from RCCI suggested that hydrocarbons were a major component of the PM mass. Further studies were conducted on this multi-cylinder engine platform to characterize the PM emissions in more detail and understand the effect of a diesel oxidation catalyst (DOC) on the hydrocarbon-dominated PM emissions. Results from the study show that the DOC can effectively reduce the hydrocarbon emissions as well as the overall PM from RCCI combustion. The bimodal size distribution of PM from RCCI is altered by the DOC which reduces the smaller mode 10 nm size particles.

Prikhodko, Vitaly Y [ORNL; Parks, II, James E [ORNL; Barone, Teresa L [ORNL; Curran, Scott [ORNL; Cho, Kukwon [ORNL; Lewis Sr, Samuel Arthur [ORNL; Storey, John Morse [ORNL; Wagner, Robert M [ORNL

2011-01-01

35

A Combustion Bomb Study of the Hydrocarbon Emissions from Engine Crevices  

Microsoft Academic Search

Two combustion bombs manufactured from a Ford 1.6L Escort production engine were used to determine the effects of engine crevice volumes on hydrocarbon emissions. Since these combustion bombs were used as static reactors, the results cannot be directly applied to an operating engine but they focus attention on the major hydrocarbon-producing crevices in an actual engine geometry.During Ihis propane-fueled experiment,

A. A. Adamczyk; E. W. Kaiser; G. A. Lavoie

1983-01-01

36

A new comprehensive reaction mechanism for combustion of hydrocarbon fuels  

SciTech Connect

A chemical kinetic model has been developed which describes pyrolysis, ignition and oxidation of many small hydrocarbon fuels over a wide range of experimental conditions. Fuels include carbon monoxide and hydrogen, methane and other alkane species up to n-butane, ethylene, propene, acetylene, and oxygenated species such as methanol, acetaldehyde and ethanol. Formation of some larger intermediate and product species including benzene, butadiene, large olefins, and cyclopentadiene has been treated in a semi-empirical manner. The reaction mechanism has been tested for conditions that do not involve transport and diffusional processes, including plug flow and stirred reactors, batch reactors and shock tubes. The present kinetic model and its validation differ from previous reaction mechanisms in two ways. First, in addition to conventional combustion data, experiments more commonly associated with chemical engineering problems such as oxidative coupling, oxidative pyrolysis and steam cracking are used to test the reaction mechanism, making it even more general than previous models. In addition, H atom abstraction and some other reaction rates, even for the smaller C{sub 2}, C{sub 3} and C{sub 4} species, are treated using approximations that facilitate future extensions to larger fuels in a convenient manner. Construction of the reaction mechanism and comparisons with experimental data illustrate the generality of the model.

Ranzi, E.; Sogaro, A.; Gaffuri, P.; Pennati, G. [Politecnico di Milano (Italy). Dipt. di Chimica Industriale e Ingegneria Chimica; Westbrook, C.K.; Pitz, W.J. [Lawrence Livermore National Lab., CA (United States)

1993-12-03

37

Computationally efficient implementation of combustion chemistry in parallel PDF calculations  

SciTech Connect

In parallel calculations of combustion processes with realistic chemistry, the serial in situ adaptive tabulation (ISAT) algorithm [S.B. Pope, Computationally efficient implementation of combustion chemistry using in situ adaptive tabulation, Combustion Theory and Modelling, 1 (1997) 41-63; L. Lu, S.B. Pope, An improved algorithm for in situ adaptive tabulation, Journal of Computational Physics 228 (2009) 361-386] substantially speeds up the chemistry calculations on each processor. To improve the parallel efficiency of large ensembles of such calculations in parallel computations, in this work, the ISAT algorithm is extended to the multi-processor environment, with the aim of minimizing the wall clock time required for the whole ensemble. Parallel ISAT strategies are developed by combining the existing serial ISAT algorithm with different distribution strategies, namely purely local processing (PLP), uniformly random distribution (URAN), and preferential distribution (PREF). The distribution strategies enable the queued load redistribution of chemistry calculations among processors using message passing. They are implemented in the software x2f{sub m}pi, which is a Fortran 95 library for facilitating many parallel evaluations of a general vector function. The relative performance of the parallel ISAT strategies is investigated in different computational regimes via the PDF calculations of multiple partially stirred reactors burning methane/air mixtures. The results show that the performance of ISAT with a fixed distribution strategy strongly depends on certain computational regimes, based on how much memory is available and how much overlap exists between tabulated information on different processors. No one fixed strategy consistently achieves good performance in all the regimes. Therefore, an adaptive distribution strategy, which blends PLP, URAN and PREF, is devised and implemented. It yields consistently good performance in all regimes. In the adaptive parallel ISAT strategy, the type and extent of redistribution is determined 'on the fly' based on the prediction of future simulation time. Compared to the PLP/ISAT strategy where chemistry calculations are essentially serial, a speed-up factor of up to 30 is achieved. The study also demonstrates that the adaptive strategy has acceptable parallel scalability.

Lu Liuyan [Sibley School of Mechanical and Aerospace Engineering, Cornell University, Upson Hall 245, Ithaca, NY 14853 (United States)], E-mail: lu.liuyan@gmail.com; Lantz, Steven R. [Center for Advanced Computing, Cornell University, Ithaca, NY 14853 (United States); Ren Zhuyin; Pope, Stephen B. [Sibley School of Mechanical and Aerospace Engineering, Cornell University, Upson Hall 245, Ithaca, NY 14853 (United States)

2009-08-20

38

Geochemical evidence for combustion of hydrocarbons during the K-T impact event  

PubMed Central

It has been proposed that extensive wildfires occurred after the Cretaceous–Tertiary (K-T) impact event. An abundance of soot and pyrosynthetic polycyclic aromatic hydrocarbons (pPAHs) in marine K-T boundary impact rocks (BIRs) have been considered support for this hypothesis. However, nonmarine K-T BIRs, from across North America, contain only rare occurrences of charcoal yet abundant noncharred plant remains. pPAHs and soot can be formed from a variety of sources, including partial combustion of vegetation and hydrocarbons whereby modern pPAH signatures are traceable to their source. We present results from multiple nonmarine K-T boundary sites from North America and reveal that the K-T BIRs have a pPAH signature consistent with the combustion of hydrocarbons and not living plant biomass, providing further evidence against K-T wildfires and compelling evidence that a significant volume of hydrocarbons was combusted during the K-T impact event.

Belcher, Claire M.; Finch, Paul; Collinson, Margaret E.; Scott, Andrew C.; Grassineau, Nathalie V.

2009-01-01

39

Modeling the unsteady combustion of solid propellants with detailed chemistry  

NASA Astrophysics Data System (ADS)

Unsteady combustion phenomena are of great interest to the solid propellant community and have been studied for many years. One area of particular interest is the relation between fluctuating pressure and propellant combustion. Pressure fluctuations, such as acoustics, naturally occur inside solid rocket combustion chambers during motor firing. Coupling between these pressure waves and the burning propellant can lead to changes in burning characteristics, a loss of performance, or even motor failure. During the past several years, various researchers have employed detailed chemical reaction mechanisms for modeling steady-state propellant combustion. The current work extends steady-state modeling into the unsteady domain and is particularly focused on the pressure-coupled phenomena. A numerical model was developed to calculate homogeneous propellant combustion under steady or unsteady conditions. The model was separated into two regions: the condensed and gas phases. Variable properties, distributed decomposition and evaporation were included in the condensed phase. The gas phase included detailed chemistry and the solution of the continuity, species, momentum and energy equations. Application was made to the cyclic nitramines, RDX and HMX. Modeling results were obtained for a wide variety of conditions including (1) steady-state; (2) quasi-steady gas phase, unsteady condensed phase; and (3) fully unsteady gas phase, unsteady condensed phase. The effects of pressure and radiant heat flux oscillations were examined through model simulations. It is believed that this work represents the first successful effort to implement both detailed kinetics and a fully unsteady gas phase for oscillatory propellant combustion. Reasonable agreement with steady-state experimental data was achieved for many combustion parameters including burning rate, surface temperature, melt layer thickness, and species concentration profiles. Pressure and heat flux responses (Rp and Rq) were obtained through numerical simulations. Reasonable agreement with experimental data was attained for many cases. In cases where the model failed to predict experimental results, explanations are given. The quasi-steady gas phase assumption was evaluated by comparing quasi-steady simulations with fully unsteady simulations at the same conditions. At low frequencies, the results coincide, but deviations begin to occur above about 100 Hz at atmospheric pressure and above about 1000 Hz for 1000 psi.

Erikson, William W.

40

Experimental study of the mild combustion of liquid hydrocarbons  

Microsoft Academic Search

A strong exhaust gas recirculation combined with air preheating generates relatively low maximum flame temperatures allowing for a better control of the furnace temperature and a lower pollutant production. While the sustainability of this combustion technology (named mild or flameless combustion) for different gaseous fuels has been extensively studied, much less information are available for liquid fuels. Consequently, this work

Marco Derudi; Renato Rota

2011-01-01

41

Reaction mechanisms in combustion: formation of soot and polycyclic aromatic hydrocarbons. Final technical report, 1 April 1980-31 March 1984  

SciTech Connect

Current and future developments in combustion require a detailed understanding of the reaction mechanism of combustion because of the conflicting demands of high-fuel economy combined with reduced noxious emissions (NO/sub x/, hydrocarbons, CO, soot) and because of the necessity of using new fuels and combustion systems. A problem of particular importance is the increased production of soot and of polycyclic aromatic hydrocarbons (PCAH) that accompanies increased use of intermittent fuel injection combustion systems, and low hydrogen/carbon fuels derived from coal rather than high hydrogen/carbon petroleum-based fuels. Objective of our program is to establish the microscopic mechanisms involved in the formation of soot in combustion processes and to develop a dynamical model that can be used to obtain a realistic simulation of the chemical processes involved in a growing soot particle. Armed with an understanding of the chemistry and dynamics, one can design optimum strategies for modifying combustion processes so as to control and reduce production of soot and PCAH.

Goddard, W.A. III

1984-07-31

42

Size distributions of polycyclic aromatic hydrocarbons in aerosol emissions from biofuel combustion  

Microsoft Academic Search

Size-resolved emission factors of polycyclic aromatic hydrocarbons (PAH), from biofuel combustion in cooking stoves in India, were measured using a dilution sampler providing sufficient dilution and quenching for aerosol stabilisation. Emission factors of PAH (total of ten compounds) from combustion of biofuels like wood, briquette and dung cake, respectively, ranged 2.0–3.2, 2.8–3.0 and 3.1–5.5mgkg?1, per mass fuel burnt and 1.9–3.3,

Chandra Venkataraman; Geeta Negi; Satya Brata Sardar; Ritu Rastogi

2002-01-01

43

Prediction of Carbon Monoxide and Hydrocarbon Emissions in Isooctane HCCI Engine Combustion Using Multi-Zone Simulations  

SciTech Connect

Homogeneous Charge Compression Ignitions (HCCI) engines show promise as an alternative to Diesel engines, yet research remains: development of practical HCCI engines will be aided greatly by accurate modeling tools. A novel detailed chemical kinetic model that incorporates information from a computational fluid mechanics code has been developed to simulate HCCI combustion. This model very accurately predicts many aspects of the HCCI combustion process. High-resolution computational grids can be used for the fluid mechanics portion of the simulation, but the chemical kinetics portion of the simulation can be reduced to a handful of computational zones (for all previous work 10 zones have been used). While overall this model has demonstrated a very good predictive capability for HCCI combustion, previous simulations using this model have tended to underpredict carbon monoxide emissions by an order of magnitude. A factor in the underprediction of carbon monoxide may be that all previous simulations have been conducted with 10 chemical kinetic zones. The chemistry that results in carbon monoxide emissions is very sensitive to small changes in temperature within the engine. The resolution in temperature is determined directly by the number of zones. This paper investigates how the number of zones (i.e. temperature resolution) affects the model's prediction of hydrocarbon and carbon monoxide emissions in an HCCI engine. Simulations with 10, 20, and 40 chemical kinetic zones have been conducted using a detailed chemical kinetic mechanism (859 species, 3606 reactions) to simulate an isooctane fueled HCCI engine. The results show that 10-zones are adequate to resolve the hydrocarbon emissions, but a greater numbers of zones are required to resolve carbon monoxide emissions. Results are also presented that explore spatial sources of the exhaust emissions within the HCCI engine combustion chamber.

Flowers, D; Aceves, S M; Martinez-Frias, J; Dibble, R

2002-05-02

44

Formation of soot from polycyclic aromatic hydrocarbons as well as fullerenes and carbon nanotubes in the combustion of hydrocarbon  

NASA Astrophysics Data System (ADS)

The eightieth anniversary of Academician, Lenin Prize Winner Rem Ivanovich Soloukhin is an important event for the scientific association of investigators of combustion and detonation processes. R. I. Soloukhin has developed original gasdynamic laser systems based on the selective thermal excitation and mixing in a supersonic flow: efficient high-power gas-flow lasers of convective type with electric excitation and chemical lasers initiated by an electron beam. He proposed methods of measuring the rapidly changing pressure, density, temperature, and other parameters of processes occurring in shock waves. Deputy Editor-in-Chief of the Journal "Fizika Goreniya Vzryva," Professor at Novosibirsk University R. I. Soloukhin trained a Pleiad of Doctors and Candidates of Sciences. His fundamental investigations form the basis for the development of new directions in the physics of combustion and explosion. In the present article, recent works on soot formation in the combustion of hydrocarbons are reviewed. The phenomenology, kinetics, and mechanism of soot formation, the influence of different factors on the formation of polycyclic aromatic hydrocarbons, fullerenes, carbon nanotubes, and soot, low-temperature cold-flame soot formation, the combustion in an electric field, and the paramagnetism of soot particles were considered from the environmental standpoint.

Mansurov, Z. A.

2011-01-01

45

Corrosion prevention in hydrocarbon-fueled booster engine combustion chamber liners  

Microsoft Academic Search

Static and dynamic tests with methane fuels containing trace amounts of sulfur compounds were performed in order to identify and develop procedures to protect against the corrosive interaction process that occurs between the fuel and the copper combustion chamber liner materials in the coolant side of a regeneratively cooled hydrocarbon booster engine. Foils of gold, platinum, zirconium, iridium, niobium, and

S. D. Rosenberg; M. L. Gage

1989-01-01

46

Evidence of Summertime Firn and Ambient Halogen Radical Chemistry from Hydrocarbon Measurements at Summit, Greenland  

NASA Astrophysics Data System (ADS)

As part of the Summit Halogen and HOx Photochemistry Experiment (GSHOX), canister samples were collected at Summit (72°N, 38°W), Greenland, from May 13 to June 16, 2007, and from June 6 to July 9, 2008, and analyzed for nonmethane hydrocarbons. These samples were combined with our previous results to create a nonmethane hydrocarbon data set spanning ten field seasons from 1997 to 2008. Nonmethane hydrocarbons are removed at different rates from the atmosphere by photochemical oxidation, typically by OH radicals. Cl and Br radicals are recognized to play an important role as photochemical oxidants in coastal regions, and hydrocarbon data from Summit suggests that halogen radicals may also be significant oxidants in remote non-coastal arctic environments. Certain hydrocarbons are known to react at different rates with OH, Cl, and Br radicals, therefore hydrocarbon concentration changes can be related to radical reaction rate constants as a method of indirectly determining the presence of halogen radical chemistry. Here we present ambient and surface firn measurements of C2-C6 hydrocarbons as indirect evidence of halogen radical chemistry occurring during the summertime at Summit, Greenland. Evidence of Cl atom chemistry was evaluated by investigating the relationship between iso-butane and n-butane, and evidence of Br atom chemistry was examined through the relationship between ethyne and benzene.

Gorham, K. A.; Beyersdorf, A. J.; Blake, N. J.; Swanson, A.; Meinardi, S.; Blake, D. R.

2008-12-01

47

Chemical Kinetic Reaction Mechanisms for Combustion of Hydrocarbon and Other Types of Chemical Fuels  

DOE Data Explorer

Reaction mechanisms have been tested and validated extensively through comparisons between computed results and measured data from laboratory experiments (e.g., shock tubes, laminar flames, rapid compression machines, flow reactors, stirred reactors) and from practical systems (e.g., diesel engines, spark-ignition engines, homogeneous charge, compression ignition (HCCI) engines). These kinetic models are used to examine a wide range of combustion systems.[Taken from https://www-pls.llnl.gov/?url=science_and_technology-chemistry-combustion

48

Nitrogen chemistry during burnout in fuel-staged combustion  

SciTech Connect

A parametric study of the chemistry of the burnout zone in reburning has been performed in laboratory plug flow reactors in the temperature range 800--1,350 K. Inlet mole fractions of NO, NH{sub 3}, HCN, CO, and O{sub 2} were varied, together with different temperatures and residence times to simulate reaction conditions in practical systems. Under lean conditions, a minimum in NO emission exists as a function of temperature. Both HCN and NH{sub 3} can act as either NO reductants or as sources for NO by oxidation. Reactions and selectivities for HCN and NH{sub 3} are controlled by the radical pool produced by fuel (CO) oxidation. As increasing amounts of CO were added, temperatures for both ignition and the minimum in NO became lower. At 2% CO, 4% O{sub 2}, and 100 ms residence time, the minimum in NO was found at approximately 1,000 K. At low temperatures, significant amounts of N{sub 2}O were measured in the reactor outlet. This is attributed to N{sub 2}O formation by HCN/NO reactions and to the slow decomposition of N{sub 2}O at these temperatures. Large reductions in NO were seen under fuel-rich conditions and at high temperatures. The observed NO reduction was very much dependent on the inlet mole fraction of O{sub 2}. Detailed chemical kinetic modeling of the experiments showed reasonable predictions for overall fuel-lean conditions, but the model failed to predict experimental results under fuel-rich conditions. The present results provide guidelines for optimizing the conditions for the burnout process of reburning, as well as other processes for NO{sub x} reduction by staged combustion. The results also provide a test basis for verifying kinetic models for nitrogen chemistry at low temperatures (800--1,350 K).

Kristensen, P.G.; Glarborg, P.; Dam-Johansen, K. [Technical Univ. of Denmark, Lyngby (Denmark). Dept. of Chemical Engineering

1996-11-01

49

Numerical modeling of chemistry and gas dynamics during shock-induced ethylene combustion  

Microsoft Academic Search

We present the results of a numerical study of shock-induced ethylene combustion. As in other reactive flow problems the computational time increases significantly when finite rate chemistry is included. We compare the accuracy and efficiency of a variety of methods when applied to this combustion problem. For a full kinetics scheme we consider the speed of a range of alternative

L. J. Clifford; A. M. Milne; B. A. Murray

1996-01-01

50

Ammonia chemistry in oxy-fuel combustion of methane  

SciTech Connect

The oxidation of NH{sub 3} during oxy-fuel combustion of methane, i.e., at high [CO{sub 2}], has been studied in a flow reactor. The experiments covered stoichiometries ranging from fuel rich to very fuel lean and temperatures from 973 to 1773 K. The results have been interpreted in terms of an updated detailed chemical kinetic model. A high CO{sub 2} level enhanced formation of NO under reducing conditions while it inhibited NO under stoichiometric and lean conditions. The detailed chemical kinetic model captured fairly well all the experimental trends. According to the present study, the enhanced CO concentrations and alteration in the amount and partitioning of O/H radicals, rather than direct reactions between N-radicals and CO{sub 2}, are responsible for the effect of a high CO{sub 2} concentration on ammonia conversion. When CO{sub 2} is present as a bulk gas, formation of NO is facilitated by the increased OH/H ratio. Besides, the high CO levels enhance HNCO formation through NH{sub 2}+CO. However, reactions NH{sub 2}+ O to form HNO and NH{sub 2}+H to form NH are inhibited due to the reduced concentration of O and H radicals. Instead reactions of NH{sub 2} with species from the hydrocarbon/methylamine pool preserve reactive nitrogen as reduced species. These reactions reduce the NH{sub 2} availability to form NO by other pathways like via HNO or NH and increase the probability of forming N{sub 2} instead of NO. (author)

Mendiara, Teresa; Glarborg, Peter [Department of Chemical and Biochemical Engineering, Technical University of Denmark, 2800 Lyngby (Denmark)

2009-10-15

51

Combustion characteristics of hydrogen–hydrocarbon hybrid fuels  

Microsoft Academic Search

A comparative study of the flame structure and characteristics of diffusion flames of the mixture of hydrogen–hydrocarbon (natural gas and propane) hybrid fuel in a slow co-flowing stream of air is presented. The volumetric content of natural gas and propane in the mixture was varied from 0–35%. The burner exit Reynolds number was varied from 150–3000. Measurements include flame length,

Ahsan R Choudhuri; S. R Gollahalli

2000-01-01

52

Quantitative Aspects of Alkylperoxy Radical Isomerization During Hydrocarbon Combustion  

Microsoft Academic Search

Detailed studies of the distribution of the products formed in the different regimes of combustion of n-pentane indicate the importance in the overall oxidation mechanism of the isomerization of amylperoxy radicals. It has been shown that C_5 O-heterocycles and C_5 alkenes are formed as a result of the intramolecular rearrangement of such radicals but that O-heterocycles, carbonyl compounds and alkenes

C. F. Cullis; M. Saeed; D. L. Trimm

1967-01-01

53

Vented explosion overpressures from combustion of hydrogen and hydrocarbon mixtures  

Microsoft Academic Search

Experimental data obtained for hydrogen mixtures in a room-size enclosure are presented and compared with data for propane and methane mixtures. This set of data was also used to develop a three-dimensional gasdynamic model for the simulation of gaseous combustion in vented enclosures. The experiments were performed in a 64m3 chamber with dimensions of 4.6×4.6×3.0m and a vent opening on

C. R. Bauwens; J. Chaffee; S. B. Dorofeev

2011-01-01

54

Method of improving the combustion of fuel containing hydrocarbon compounds in the combustion chamber or chambers of internal combustion engines, and a liquid composition for carrying the method into effect  

Microsoft Academic Search

For the improved combustion of hydrocarbon compounds, for example those contained in gasoline, diesel fuel etc., in internal combustion engines a liquid composition comprising hydrogen peroxide, water, aliphatic alcohol having 1-4 carbon atoms, and preferably thin lubricating oil and anticorrosive is admixed with the fuel air mixture in the internal combustion engines.

T. N. Anderberg; A. Mellovist

1982-01-01

55

Ultra-deep Desulfurization of Liquid Hydrocarbon Fuels: Chemistry and Process  

Microsoft Academic Search

Recently, ultra-deep desulfurization of liquid hydrocarbon fuels is becoming very important worldwide not only because of the heightened interest for cleaner air and thus increasingly stringent environmental regulations for fuel sulfur content, but also because of the great need for making ultra-low-sulfur fuels used in hydrocarbon fuel process for fuel cell applications. This article is a selective review on chemistry

Chunshan Song; Xiaoliang Ma

2004-01-01

56

Investigating an annular nozzle on combustion products of hydrocarbon fuels  

NASA Astrophysics Data System (ADS)

Full-scale and computational experiments were used to investigate the flows in the jet thrust unit with annular nozzle and deflector in the form of a spherical segment. The used working gas was the combustion products of air mixtures with acetylene, gas-phase aviation kerosene, and natural gas. Experimental studies were carried out in a hot-shot wind tunnel in the range of stagnation pressure from 0.48 to 2.05 MPa. The calculations for the cases of combustion products outflow in terrestrial and high altitude conditions were performed with the original computer program that used the Euler and Navier-Stokes systems supplemented by equations of chemical kinetics. It was found that the thrust of the jet module with an annular nozzle at high altitude almost twice exceeds the sound nozzle thrust, but is lesser (about 25 %) than the thrust of the ideal calculated Laval nozzle; the difference therewith decreases markedly with the decrease of flight altitude and stagnation pressure.

Levin, V. A.; Afonina, N. E.; Gromov, V. G.; Smekhov, G. D.; Khmelevsky, A. N.; Markov, V. V.

2013-09-01

57

Effect of laser radiation and electric field on combustion of hydrocarbon-air mixtures  

Microsoft Academic Search

Publications on combustion of hydrocarbon-air mixtures under the action of a weak electric field and laser radiation are analyzed.\\u000a A specific feature of the authors’ experimental study is a pulsed-periodic action of an electric field and focused laser radiation,\\u000a which does not lead to electric discharge or optical breakdown. Numerous experiments reveal a noticeable effect of weak electric\\u000a fields on

P. K. Tretyakov; A. V. Tupikin; V. N. Zudov

2009-01-01

58

An integrated aerodynamic-ramp-injector\\/plasma-torch-igniter for supersonic combustion applications with hydrocarbon fuels  

Microsoft Academic Search

The first integrated, flush-wall, aero-ramp-fuel-injector\\/plasma-torch igniter and flame propagation system for supersonic combustion applications with hydrocarbon fuels was developed and tested. The main goal of this project was to develop a device which could be used to demonstrate that the correct placement of a plasma-torch-igniter\\/flame-holder in the wake of the fuel jets of an aero-ramp injector array could make sustained,

Lance Steven Jacobsen

2001-01-01

59

Burn-out calculations for atomized hydrocarbon fuel in gas turbine combustion chambers  

Microsoft Academic Search

1.A method is proposed for calculating the burn-out of atomized hydrocarbon fuel in gas turbine combustion chambers, in which an evaporation mechanism is realized. (The corresponding value of the Spalding criterion Sl?Lx==f(te\\/tc.t).3.Comparison of the experimental data with the theoretical curve, based on the proposed method of calculation, has shown that the total burn-out times are the same with an accuracy

R. S. Tyul'panov

1966-01-01

60

Inhibition of the Formation of 3,4-Benzpyrene during Hydrocarbon Combustion  

Microsoft Academic Search

IT is well known that polycyclic hydrocarbons including the carcinogen 3,4-benzpyrene occur in association with the carbonaceous deposits or smokes resulting from the incomplete combustion of a wide variety of organic materials. Thus 3,4-benzpyrene has been identified in soots, carbon black, certain smoked foods, cigarette- and tobacco-smoke and in the exhaust smoke of Diesel engines. The mode of formation of

R. Long; S. K. Ray

1961-01-01

61

UV absorption of CO 2 for temperature diagnostics of hydrocarbon combustion applications  

Microsoft Academic Search

At room temperature, CO2 is transparent in the ultraviolet (UV) at wavelengths longer than 205nm; however, at temperatures above 1000K the CO2 absorption cross-section becomes significant in the region between 200 and 320nm. Because CO2 is a major product of hydrocarbon combustion and because both the magnitude of the absorption cross-section and the shape of the UV absorption spectrum vary

J. B. Jeffries; C. Schulz; D. W. Mattison; M. A. Oehlschlaeger; W. G. Bessler; T. Lee; D. F. Davidson; R. K. Hanson

2005-01-01

62

When taking an efficiency test: Understand basic combustion chemistry  

Microsoft Academic Search

Number 2 fueloil is a hydrocarbon consisting of 85% carbon and 15% hydrogen. In its liquid state, it is totally inactive and non volatile, making it very safe to store. But when the proper change of state takes place, it will vaporize, become activated and extremely volatile. There are three phases which must take place before the liquid hydrocarbon will

Petruzzi

1995-01-01

63

A Study on NO Reduction Caused by Thermal Cracking Hydrocarbons during Rich Diesel Combustion  

NASA Astrophysics Data System (ADS)

This study tries to investigate the reduction of nitric oxide by thermally cracked hydrocarbons under rich condition during diesel combustion. Experiments using flow reactor system, which follows the chemical process of fuel at high temperature and atmospheric pressure, show that thermal cracking of fuel starts at about 1000K, and lower hydrocarbons mainly composed of C2H4 and CH4 are formed. NO can be reduced when fuel is thermally cracked and oxidized. A larger amount of NO is reduced when thermal cracking hydrocarbons are increased in quantity under rich and high temperature condition. Among decomposed hydrocarbons, C2H4 is easily decomposed and affects deNO mechanism. Chemical kinetic calculation using CHEMKIN III reveals the mechanism. NO is reduced through the reaction of HCCO or CH2 with NO. In these reaction paths, C2H2 is an essential species. The computation also shows that this deNO mechanism can be actualized in the practical diesel combustion.

Noge, Hirofumi; Kidoguchi, Yoshiyuki; Miwa, Kei

64

Diazido alkanes and diazido alkanols as combustion modifiers for liquid hydrocarbon ramjet fuels  

SciTech Connect

This invention relates to liquid-hydrocarbon jet fuels and more particularly to azido additives to liquid-hydrocarbon ramjet fuels. In most liquid-fueled combustors such as the ramjet, the fuel is directly introduced into the upstream flow section of the combustion chamber in the form of sprays of droplets. These droplets subsequently mix with the external gas, heat up, gasify, combust, and thereby release heat to provide the propulsion energy. It is therefore obvious that the rates of gasification and mixing would closely affect the chemical heat release rate and, consequently, such important performance parameters as combustion efficiency and the tendency to exhibit combustion instability. Accordingly, and object of this invention is to provide a new, improved jet fuel and provide new additives for jet fuels. A further object of this invention is to provide a more-efficient jet fuel and reduce the ignition time for jet fuels. Still, a further object of this invention is to improve the mixing characteristics of the jet-fuel spray.

Miller, R.S.

1986-07-03

65

Stabilization of liquid hydrocarbon fuel combustion by using a programmable microwave discharge in a subsonic airflow  

NASA Astrophysics Data System (ADS)

Under conditions of a programmable discharge (a surface microwave discharge combined with a dc discharge), plasma-enhanced combustion of alcohol injected into a subsonic ( M = 0.3-0.9) airflow in the drop (spray) phase is stabilized. It is shown that the appearance of the discharge, its current-voltage characteristic, the emission spectrum, the total emission intensity, the heat flux, the electron density, the hydroxyl emission intensity, and the time dependences of the discharge current and especially discharge voltage change substantially during the transition from the airflow discharge to stabilized combustion of the liquid hydrocarbon fuel. After combustion stabilization, more than 80% of liquid alcohol can burn out, depending on the input power, and the flame temperature reaches ˜2000 K.

Kopyl, P. V.; Surkont, O. S.; Shibkov, V. M.; Shibkova, L. V.

2012-06-01

66

Stabilization of liquid hydrocarbon fuel combustion by using a programmable microwave discharge in a subsonic airflow  

SciTech Connect

Under conditions of a programmable discharge (a surface microwave discharge combined with a dc discharge), plasma-enhanced combustion of alcohol injected into a subsonic (M = 0.3-0.9) airflow in the drop (spray) phase is stabilized. It is shown that the appearance of the discharge, its current-voltage characteristic, the emission spectrum, the total emission intensity, the heat flux, the electron density, the hydroxyl emission intensity, and the time dependences of the discharge current and especially discharge voltage change substantially during the transition from the airflow discharge to stabilized combustion of the liquid hydrocarbon fuel. After combustion stabilization, more than 80% of liquid alcohol can burn out, depending on the input power, and the flame temperature reaches {approx}2000 K.

Kopyl, P. V.; Surkont, O. S.; Shibkov, V. M.; Shibkova, L. V. [Moscow State University, Faculty of Physics (Russian Federation)

2012-06-15

67

Selectivity in hydrocarbon catalytic reforming: a surface chemistry perspective  

Microsoft Academic Search

A brief overview of the recent advances in the understanding of the reaction mechanisms of hydrocarbon reforming processes is provided. Emphasis is placed on the knowledge developed by studies using model single-crystal metals and modern surface analytical techniques. An argument is presented for the early definition of reaction selectivities in these processes because of subtle relative changes in dehydrogenation rates.

Francisco Zaera

2002-01-01

68

Detailed chemistry flamelet modeling of mixed-mode combustion in spark-assisted HCCI engines  

Microsoft Academic Search

A detailed chemistry mixed-mode flamelet model for the prediction of combustion in spark-assisted homogeneous charge compression ignition (HCCI) engines is presented in this paper.The complex phenomena of spark-channel processes (turbulent corrugation, multiple restrikes) and of early flame kernel propagation (localized flame kernel formation, non-spherical early flame shapes), both induced by spray-guided spark-ignition combustion initiation, are captured by the recently introduced

R. Dahms; C. Felsch; O. Röhl; N. Peters

2011-01-01

69

Chemistry and the Internal Combustion Engine II: Pollution Problems.  

ERIC Educational Resources Information Center

|Discusses pollution problems which arise from the use of internal combustion (IC) engines in the United Kingdom (UK). The IC engine exhaust emissions, controlling IC engine pollution in the UK, and some future developments are also included. (HM)|

Hunt, C. B.

1979-01-01

70

Impact of reactive nitrogen emissions from fossil fuel combustion and biomass burning on atmospheric chemistry  

Microsoft Academic Search

The increasing desire for energy in our society has caused changes in our environment. One of the byproducts of energy consumption is the emission of nitrogen oxides from combustion processes. Nitrogen oxides play an important role in atmospheric chemistry on local, regional, and global scales. They are considered primary pollutants which can chemically react and contribute to photochemical smog. They

J. Dignon; J. E. Penner; C. S. Atherton; J. J. Walton

1991-01-01

71

The inorganic chemistry of the combustion of wheat straw  

Microsoft Academic Search

Equilibrium calculations of the combustion of wheat straw in an excess of air at 1 atm were carried out at temperatures ranging from 500–1200°C. A low melting molten silicate was present at all temperatures which, in addition to a large concentration of silica (76–83 mol%) and potassium (10–12 mol%) contained small concentrations (

Milton Blander; Arthur D. Pelton

1997-01-01

72

ON UPGRADING THE NUMERICS IN COMBUSTION CHEMISTRY CODES. (R824970)  

EPA Science Inventory

A method of updating and reusing legacy FORTRAN codes for combustion simulations is presented using the DAEPACK software package. The procedure is demonstrated on two codes that come with the CHEMKIN-II package, CONP and SENKIN, for the constant-pressure batch reactor simulati...

73

Combustion  

NSDL National Science Digital Library

In this chemistry activity, learners discover that the weight of the product of combustion is greater than that of the starting material. Learners will compare the weight of steel wool before and after it is heated. Learners are asked to consider why the steel wool weighs more (oxidation) as well as write the balanced chemical equation for the burning of steel. This activity uses an open flame; adult supervision is recommended. The resource includes notes for educators and extension ideas.

House, The S.

2013-05-15

74

Impact of biogenic hydrocarbons on tropospheric chemistry: results from a global chemistry-climate model  

NASA Astrophysics Data System (ADS)

We present a description and evaluation of LMDz-INCA, a global three-dimensional chemistry-climate model, pertaining to its recently developed NMHC version. In this substantially extended version of the model a comprehensive representation of the photochemistry of non-methane hydrocarbons (NMHC) and volatile organic compounds (VOC) from biogenic, anthropogenic, and biomass-burning sources has been included. The tropospheric annual mean methane (9.2 years) and methylchloroform (5.5 years) chemical lifetimes are well within the range of previous modelling studies and are in excellent agreement with estimates established by means of global observations. The model provides a reasonable simulation of the horizontal and vertical distribution and seasonal cycle of CO and key non-methane VOC, such as acetone, methanol, and formaldehyde as compared to observational data from several ground stations and aircraft campaigns. LMDz-INCA in the NMHC version reproduces tropospheric ozone concentrations fairly well throughout most of the troposphere. The model is applied in several sensitivity studies of the biosphere-atmosphere photochemical feedback. The impact of surface emissions of isoprene, acetone, and methanol is studied. These experiments show a substantial impact of isoprene on tropospheric ozone and carbon monoxide concentrations revealing an increase in surface O3 and CO levels of up to 30 ppbv and 60 ppbv, respectively. Isoprene also appears to significantly impact the global OH distribution resulting in a decrease of the global mean tropospheric OH concentration by approximately 0.9×105 molecules cm-3 or roughly 10% and an increase in the global mean tropospheric methane lifetime by approximately four months. A global mean ozone net radiative forcing due to the isoprene induced increase in the tropospheric ozone burden of 0.09W m-2 is found. The key role of isoprene photooxidation in the global tropospheric redistribution of NOx is demonstrated. LMDz-INCA calculates an increase of PAN surface mixing ratios ranging from 75 to 750 pptv and 10 to 250 pptv during northern hemispheric summer and winter, respectively. Acetone and methanol are found to play a significant role in the upper troposphere/lower stratosphere (UT/LS) budget of peroxy radicals. Calculations with LMDz-INCA show an increase in HOx concentrations region of 8 to 15% and 10 to 15% due to methanol and acetone biogenic surface emissions, respectively. The model has been used to estimate the global tropospheric CO budget. A global CO source of 3019 TgCO yr-1 is estimated. This source divides into a primary source of 1533 TgCO yr-1 and secondary source of 1489 TgCO yr-1 deriving from VOC photooxidation. Global VOC-to-CO conversion efficiencies of 90% for methane and between 20 and 45% for individual VOC are calculated by LMDz-INCA.

Folberth, G. A.; Hauglustaine, D. A.; Lathière, J.; Brocheton, F.

2005-10-01

75

Using distonic radical ions to probe the chemistry of key combustion intermediates: the case of the benzoxyl radical anion.  

PubMed

The benzoxyl radical is a key intermediate in the combustion of toluene and other aromatic hydrocarbons, yet relatively little experimental work has been performed on this species. Here, a combination of electrospray ionization (ESI), multistage mass spectrometry experiments, and density functional theory (DFT) calculations are used to examine the formation and fragmentation of a benzoxyl (benzyloxyl) distonic radical anion. Excited 4-carboxylatobenzoxyl radical anions were produced via two methods: (1) collision induced dissociation (CID) of the nitrate ester 4-(nitrooxymethyl)benzoate, (-)O2CC6H4CH2ONO2, and (2) reaction of ozone with the 4-carboxylatobenzyl radical anion, (-)O2CC6H4CH2(•). In neither case was the stabilized (-)O2CC6H4CH2O(•) radical anion intermediate detected. Instead, dissociation products at m/z 121 and 149 were observed. These products are attributed to benzaldehyde (O2(-)CC6H4CHO) and benzene ((-)O2CC6H5) products from respective loss of H and HCO radicals in the vibrationally excited benzoxyl intermediate. In no experiments was a product at m/z 120 (i.e., (-)O2CC6H4(•)) detected, corresponding to absence of the commonly assumed phenyl radical + CH2=O channel. The results reported suggest that distonic ions are useful surrogates for reactive intermediates formed in combustion chemistry. PMID:23512425

Li, Cong; Lam, Adrian K Y; Khairallah, George N; White, Jonathan M; O'Hair, Richard A J; da Silva, Gabriel

2013-03-20

76

Using Distonic Radical Ions to Probe the Chemistry of Key Combustion Intermediates: The Case of the Benzoxyl Radical Anion  

NASA Astrophysics Data System (ADS)

The benzoxyl radical is a key intermediate in the combustion of toluene and other aromatic hydrocarbons, yet relatively little experimental work has been performed on this species. Here, a combination of electrospray ionization (ESI), multistage mass spectrometry experiments, and density functional theory (DFT) calculations are used to examine the formation and fragmentation of a benzoxyl (benzyloxyl) distonic radical anion. Excited 4-carboxylatobenzoxyl radical anions were produced via two methods: (1) collision induced dissociation (CID) of the nitrate ester 4-(nitrooxymethyl)benzoate, -O2CC6H4CH2ONO2, and (2) reaction of ozone with the 4-carboxylatobenzyl radical anion, -O2CC6H4CH2 •. In neither case was the stabilized -O2CC6H4CH2O• radical anion intermediate detected. Instead, dissociation products at m/ z 121 and 149 were observed. These products are attributed to benzaldehyde (O2 -CC6H4CHO) and benzene (-O2CC6H5) products from respective loss of H and HCO radicals in the vibrationally excited benzoxyl intermediate. In no experiments was a product at m/ z 120 (i.e., -O2CC6H4 •) detected, corresponding to absence of the commonly assumed phenyl radical + CH2=O channel. The results reported suggest that distonic ions are useful surrogates for reactive intermediates formed in combustion chemistry.

Li, Cong; Lam, Adrian K. Y.; Khairallah, George N.; White, Jonathan M.; O'Hair, Richard A. J.; da Silva, Gabriel

2013-04-01

77

Hydrocarbon measurements during tropospheric ozone depletion events: Evidence for halogen atom chemistry  

Microsoft Academic Search

During the Arctic Tropospheric Ozone Chemistry 1996 (ARCTOC 96) field campaign (March 29 to May 15, 1996), in situ measurements of C2-C8 hydrocarbons, selected C1-C2 halocarbons, and carbon monoxide were carried out at Ny Ålesund, Svalbard (78°55'N,11°56'E). Two major tropospheric ozone depletions were observed during this period. In each case, concurrent depletion of alkanes and ethyne but no significant changes

B. Ramacher; J. Rudolph; R. Koppmann

1999-01-01

78

Emissions of polycyclic aromatic hydrocarbons from combustion of agricultural and sylvicultural debris  

NASA Astrophysics Data System (ADS)

In this work, 28 parent and substituted-polycyclic aromatic hydrocarbons (PAHs) have been quantified in 76 smoke samples produced by burning pine wood, pine needles, prickly pear and almond skin using two different kinds of combustion devices. The results show a great variability in the total concentrations of the PAHs, while their proportions in the different samples are practically independent of the type of biomass that is burned. Just a few PAHs with low molecular weight—naphthalene, 1- and 2-methylnaphthalene, acenaphthylene and phenanthrene—are the most common in the different smoke samples, representing between 61% and 72% of the total. The high correlation coefficients between naphthalene and the total concentrations of PAHs, or between naphthalene and the concentrations of PAHs grouped by number of rings, demonstrate that all combustion processes studied are equally affected by the variables that regulate those processes. The results underscore the important role that naphthalene plays in the formation of higher molecular weight PAHs by pyrosynthesis and show that the naphthalene concentration can be used as an indicator of the total hydrocarbons content in the smoke.

Conde, Francisco J.; Ayala, Juan H.; Afonso, Ana M.; González, Venerando

79

A role of hydrocarbon reaction for NO{sub x} formation and reduction in fuel-rich pulverized coal combustion  

SciTech Connect

We have investigated an index for modeling a NO{sub x} reaction mechanism of pulverized coal combustion. The reaction mechanism of coal nitrogen was examined by drop-tube furnace experiments under various burning conditions. We proposed the gas phase stoichiometric ratio (SRgas) as a key index to evaluate NO{sub x} concentration in fuel-rich flames. The SRgas was defined as: SRgas {identical_to} amount of fuel required for stoichiometry combustion/amount of gasified fuel where, the amount of gasified fuel was defined as the amount of fuel which had been released to the gas phase by pyrolysis, oxidation and gasification reactions. When SRgas < 1.0, NO{sub x} concentration was strongly influenced by the value of SRgas. In this condition, the NO{sub x} concentration was hardly influenced by coal type, particle diameter, or reaction time. We developed a model to analyze NO{sub x} and XN(HCN, NH{sub 3}) concentrations for pulverized coal/air combustion and coal/CO{sub 2}/O{sub 2} combustion, based on the index. NO{sub x} and XN concentrations did not reproduce the experimental results without considering reactions between hydrocarbons and NO{sub x}. The hydrocarbon reaction was important for both NO{sub x} and XN, especially for air combustion. In the present model, an empirical formula was used to estimate the total concentration of hydrocarbons in coal flame. The reaction of heavy hydrocarbons which had plural aromatic rings was very important to analyze the reaction mechanism of hydrocarbons for coal combustion in detail. When burning temperature and SRgas were the same, total hydrocarbon concentration in a coal flame was larger than that of a light gaseous hydrocarbon flame. Total hydrocarbon concentration in oxy-fuel combustion was lower than that in air combustion. We verified the proposed model by experimental results obtained for a drop-tube furnace and a laboratory-scale furnace that had an installed low-NO{sub x} burner. (author)

Taniguchi, Masayuki; Kamikawa, Yuki; Okazaki, Teruyuki; Yamamoto, Kenji; Orita, Hisayuki [Energy and Environmental Systems Laboratory, Hitachi, Ltd. Power Systems Company, 7-2-1 Omika-cho, Hitachi-shi, Ibaraki-ken 319-1292 (Japan)

2010-08-15

80

Decomposition, combustion, and detonation chemistry of energetic materials  

SciTech Connect

Progress in the understanding of energetic materials from the initial synthesis, in the nonreacting state, and finally during decomposition on timescales from hours to picoseconds has markedly advanced in recent years. A major factor has been the incorporation of advanced diagnostics, such as AFM, broadband time-resolved spectroscopy, laser methods, high-level theory, and high-speed computing. New and unusual compounds, which have been sought on the basis of theoretically optimized properties, are progressing from imagination to reality. Control over physical properties, such as defect number and crystal growth characteristics, is occurring. Promising new levels of understanding about reaction pathways, kinetics, sensitivity mechanisms, combustion mechanisms, and shock fronts are being gained. The focus on component materials has continued to expand beyond studies of the neat oxidizers and monopropellants to the behavior of binders, metals and metalloids, and whole new classes of compounds. Many novel materials were mentioned throughout this symposium. The volume is divided into the following topical sections: Synthesis and characterization (13 papers); Thermal decomposition (6); Combustion mechanics (14); and Initiation and detonation (26). Papers have been processed separately for inclusion on the data base.

Brill, T.B. [ed.] [Univ. of Delaware, Newark, DE (United States); Russell, T.P. [ed.] [Naval Research Lab., Washington, DC (United States); Tao, W.C. [ed.] [Lawrence Livermore National Lab., CA (United States); Wardle, R.B. [ed.] [Thiokol Corp., Brigham City, UT (United States)

1996-07-01

81

Emission of Oxygenated Polycyclic Aromatic Hydrocarbons from Indoor Solid Fuel Combustion  

PubMed Central

Indoor solid fuel combustion is a dominant source of polycyclic aromatic hydrocarbons (PAHs) and oxygenated PAHs (OPAHs) and the latter are believed to be more toxic than the former. However, there is limited quantitative information on the emissions of OPAHs from solid fuel combustion. In this study, emission factors of OPAHs (EFOPAH) for nine commonly used crop residues and five coals burnt in typical residential stoves widely used in rural China were measured under simulated kitchen conditions. The total EFOPAH ranged from 2.8±0.2 to 8.1±2.2 mg/kg for tested crop residues and from 0.043 to 71 mg/kg for various coals and 9-fluorenone was the most abundant specie. The EFOPAH for indoor crop residue burning were 1~2 orders of magnitude higher than those from open burning, and they were affected by fuel properties and combustion conditions, like moisture and combustion efficiency. For both crop residues and coals, significantly positive correlations were found between EFs for the individual OPAHs and the parent PAHs. An oxygenation rate, Ro, was defined as the ratio of the EFs between the oxygenated and parent PAH species to describe the formation potential of OPAHs. For the studied OPAH/PAH pairs, mean Ro values were 0.16 ~ 0.89 for crop residues and 0.03 ~ 0.25 for coals. Ro for crop residues burned in the cooking stove were much higher than those for open burning and much lower than those in ambient air, indicating the influence of secondary formation of OPAH and loss of PAHs. In comparison with parent PAHs, OPAHs showed a higher tendency to be associated with particulate matter (PM), especially fine PM, and the dominate size ranges were 0.7 ~ 2.1 µm for crop residues and high caking coals and < 0.7 µm for the tested low caking briquettes.

Shen, Guofeng; Tao, Shu; Wang, Wei; Yang, Yifeng; Ding, Junnan; Xue, Miao; Min, Yujia; Zhu, Chen; Shen, Huizhong; Li, Wei; Wang, Bin; Wang, Rong; Wang, Wentao; Wang, Xilong; Russell, Armistead G.

2011-01-01

82

Standard test method for heat of combustion of hydrocarbon fuels by bomb calorimeter (high-precision method)  

SciTech Connect

This method covers the determination of the heat of combustion of hydrocarbon fuels. It is designed specifically for use with aviation turbine fuels when the permissible difference between duplicate determinations is of the order of 0.1%. It can be used for a wide range of volatile and nonvolatile materials where slightly greater differences in precision can be tolerated. The heat of combustion is determined by burning a weighed sample in an oxygen-bomb calorimeter under controlled conditions. The temperature is measured by means of a platinum resistance thermometer. The heat of combustion is calculated from temperature observations before, during, and after combustion, with proper allowance for thermochemical and heat-transfer corrections. Either isothermal or adiabatic calorimeters may be used. The heat of combustion is a measure of the energy available from a fuel. A knowledge of this value is essential when considering the thermal efficiency of equipment for producing either power or heat.

Not Available

1980-01-01

83

Experimental study of the ignition of liquid hydrocarbon fuels and stabilization of their combustion by an arc discharge  

NASA Astrophysics Data System (ADS)

The ignition of liquid hydrocarbon fuels and stabilization of their combustion by an arc discharge in a supersonic air flow are investigated experimentally. The discharge parameters and flame characteristics (ignition time lag) are determined. It is shown that the average energy deposited in the flow by the igniter is five orders of magnitude less than the kinetic energy of the main gas flow.

Bityurin, V. A.; Velikodnyi, V. Yu.; Tolkunov, B. N.; Bykov, A. A.; Dyrenkov, A. V.; Popov, V. V.

2012-12-01

84

Low and High Temperature Combustion Chemistry of Butanol Isomers in Premixed Flames and Autoignition Systems  

Microsoft Academic Search

Butanol is a fuel that has been proposed as a bio-derived alternative to conventional petroleum derived fuels. The structural isomer in traditional 'bio-butanol' fuel is n-butanol, but newer conversion technologies produce iso-butanol as a fuel. In order to better understand the combustion chemistry of bio-butanol, this study presents a comprehensive chemical kinetic model for all the four isomers of butanol

S M Sarathy; W J Pitz; C K Westbrook; M Mehl; K Yasunaga; H J Curran; T Tsujimura; P Osswald; K Kohse-Hoinghaus

2010-01-01

85

Combustion of butanol isomers - A detailed molecular beam mass spectrometry investigation of their flame chemistry  

Microsoft Academic Search

The combustion chemistry of the four butanol isomers, 1-, 2-, iso- and tert-butanol was studied in flat, premixed, laminar low-pressure (40 mbar) flames of the respective alcohols. Fuel-rich ( = 1.7) butanol-oxygen-(25%)argon flames were investigated using different molecular beam mass spectrometry (MBMS) techniques. Quantitative mole fraction profiles are reported as a function of burner distance. In total, 57 chemical compounds,

Patrick Osswald; Hanna Gueldenberg; Katharina Kohse-Hoeinghaus; Bin Yang; Tao Yuan; Fei Qi

2011-01-01

86

Combustion of butanol isomers – A detailed molecular beam mass spectrometry investigation of their flame chemistry  

Microsoft Academic Search

The combustion chemistry of the four butanol isomers, 1-, 2-, iso- and tert-butanol was studied in flat, premixed, laminar low-pressure (40mbar) flames of the respective alcohols. Fuel-rich (?=1.7) butanol–oxygen–(25%)argon flames were investigated using different molecular beam mass spectrometry (MBMS) techniques. Quantitative mole fraction profiles are reported as a function of burner distance. In total, 57 chemical compounds, including radical and

Patrick Oßwald; Hanna Güldenberg; Katharina Kohse-Höinghaus; Bin Yang; Tao Yuan; Fei Qi

2011-01-01

87

Investigation and Optimization of Biodiesel Chemistry for HCCI Combustion  

SciTech Connect

Over the past 5 years, ORNL has run 95 diesel range fuels in homogene-ous charge compression ignition (HCCI), including 40 bio-diesels and associated diesel fuels in their blending. The bio-diesel blends varied in oxygen content, iodine number, cetane, boiling point distribution, chemical composition, and some contained nitrogen. All fuels were run in an HCCI engine at 1800 rpm, in the power range of 2.5 to 4.5 bar IMEP, using intake air heating for combustion phasing control, and at a compression ratio of 10.6. The engine response to fuel variables has been analyzed statistically. Generally, the engine responded well to fuels with lower nitrogen and oxygen, lower cetane, and lower aromatics. Because of the wide range of fuels combined in the model, it provides only a broad overview of the engine response. It is recommended that data be truncated and re-modeled to obtain finer resolution of engine response to particular fuel variables.

Bunting, Bruce G [ORNL; Bunce, Michael [ORNL; Joyce, Blake [ORNL; Crawford, Robert W [Rincon Ranch Consulting

2011-01-01

88

Rapid laser-wavelength modulation spectroscopy used as a fast temperature measurement technique in hydrocarbon combustion  

SciTech Connect

A fast temperature measurement technique is described which is suitable for use in dynamic reacting gases, particularly in situations which involve hydrocarbon--air combustion. Temperature is determined from the relative intensity of a pair of fully resolved absorption lines probed with a rapid-tuning single-frequency laser. Demonstration of the technique using 300-..mu..s scans across the R/sub 1/(7) and R/sub 1/(11) lines in the (0,0) band of the A/sup 2/summation/sup +/ left-arrow X/sup 2/product system of OH present in the postflame gases above a CH/sub 4/--air flat-flame burner is reported. Fluorescence monitoring of the absorption spectra was used to provide improved spatial resolution. Temperatures inferred from simultaneous absorption and fluorescence measurements showed good agreement with radiation-corrected thermocouple scans.

Rea E.C. Jr.; Hanson, R.K.

1988-11-01

89

The Physics and Chemistry of Small Translucent Molecular Clouds. XIII. The Basic Hydrocarbon Chemistry  

Microsoft Academic Search

We have observed 10 hydrocarbon species at 3 mm wavelength in three translucent clouds and in TMC-1 and L183. The 10 species are C2H, c-C3H, l-C3H, c-C3H2, l-C3H2, CH3CCH, C4H, C4H2, C5H, and C6H, where c- and l- designate the cyclical and linear isomers. Abundances for these, as well as the previously observed species CH3C4H and C6H2, have been derived

B. E. Turner; Eric Herbst; R. Terzieva

2000-01-01

90

Role of temperature and hydrochloric acid on the formation of chlorinated hydrocarbons and polycyclic aromatic hydrocarbons during combustion of paraffin powder, polymers, and newspaper.  

PubMed

Formation of chlorinated hydrocarbons and polycyclic aromatic hydrocarbons (PAHs) were determined using a laboratory-scale incinerator when combusting materials at different temperatures, different concentrations of hydrochloric acid (HCl), and when combusting various types of polymers/newspaper. Polychlorobenzenes (PCBz), polychlorophenols (PCPhs), polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) and their toxic equivalency (TEQ) and PAHs were highlighted and reported. Our results imply maximum formation of chlorinated hydrocarbons at 400 degrees C in the following order; PCBz>or=PCPhs>PCDFs>PCDDs>TEQ on a parts-per-billion level. Similarly, a maximum concentration of chlorinated hydrocarbons was noticed with an HCl concentration at 1000 ppm with the presence of paraffin powder in the following order; PAHs>PCBz>or=PCPhs>PCDFs>PCDDs>TEQ an a parts-per-billion level. PAHs were not measured at different temperatures. Elevated PAHs were noticed with different HCl concentrations and paraffin powder combustion (range: 27-32 microg/g). While, different polymers and newspaper combusted, nylon and acrylonitrile butadiene styrene (ABS) produced the maximum hydrogen cyanide (HCN) concentration, concentrations of PCDD/FS, dioxin-like polychlorinated biphenyls (DL-PCBs), and TEQ were in a decreasing order: polyvinylchloride (PVC)

Takasuga, Takumi; Umetsu, Norihito; Makino, Tetsuya; Tsubota, Katsuya; Sajwan, Kenneth S; Kumar, Kurunthachalam Senthil

2007-05-11

91

Non intrusive spectroscopic investigations of soot and unburnt hydrocarbons in combustion gases  

NASA Astrophysics Data System (ADS)

Fourier Transform Infrared (FTIR) spectroscopy was used to investigate the IR spectral absorption of soot particles from a Palas smoke generator. A TSI Condensation Particle Counter was used to quantify the number of soot particles produced and this was related to the intensity of the IR absorption. The broad band IR absorption increases with soot particle count but quantitative measurements of total soot mass were not obtained because accurate size distributions of the particles were not available. A sample of gas turbine engine exhaust gas was analyzed by Gas Chromatography-Mass Spectroscopy to determine the primary constituent unburnt hydrocarbon (UHC) species. Their relative proportions were measured with a Flame Ionization Detector (FID). These species are predominantly unsaturated C2 to C6 hydrocarbons. The infrared absorption spectrum of the exhaust gas sample was compared with that of combustion products from a laboratory kerosene burner using a multipass White cell. These were also compared with reference spectra and IR spectra of UHCs obtained non-intrusively from gas turbine engine tests. There are IR spectral band shape differences indicating that the relative proportions of the constituent UHCs in gas turbine exhaust are different from those in a kerosene burner plume.

Hilton, Moira; Arrigone, Giovanni M.; Miller, Michael N.

1999-09-01

92

Emissions of parent, nitro, and oxygenated polycyclic aromatic hydrocarbons from residential wood combustion in rural China.  

PubMed

Residential wood combustion is one of the important sources of air pollution in developing countries. Among the pollutants emitted, parent polycyclic aromatic hydrocarbons (pPAHs) and their derivatives, including nitrated and oxygenated PAHs (nPAHs and oPAHs), are of concern because of their mutagenic and carcinogenic effects. In order to evaluate their impacts on regional air quality and human health, emission inventories, based on realistic emission factors (EFs), are needed. In this study, the EFs of 28 pPAHs (EF(PAH28)), 9 nPAHs (EF(PAHn9)), and 4 oPAHs (EF(PAHo4)) were measured for residential combustion of 27 wood fuels in rural China. The measured EF(PAH28), EF(PAHn9), and EF(PAHo4) for brushwood were 86.7 ± 67.6, 3.22 ± 1.95 × 10(-2), and 5.56 ± 4.32 mg/kg, which were significantly higher than 12.7 ± 7.0, 8.27 ± 5.51 × 10(-3), and 1.19 ± 1.87 mg/kg for fuel wood combustion (p < 0.05). Sixteen U.S. EPA priority pPAHs contributed approximately 95% of the total of the 28 pPAHs measured. EFs of pPAHs, nPAHs, and oPAHs were positively correlated with one another. Measured EFs varied obviously depending on fuel properties and combustion conditions. The EFs of pPAHs, nPAHs, and oPAHs were significantly correlated with modified combustion efficiency and fuel moisture. Nitro-naphthalene and 9-fluorenone were the most abundant nPAHs and oPAHs identified. Both nPAHs and oPAHs showed relatively high tendencies to be present in the particulate phase than pPAHs due to their lower vapor pressures. The gas-particle partitioning of freshly emitted pPAHs, nPAHs, and oPAHs was primarily controlled by organic carbon absorption. PMID:22765266

Shen, Guofeng; Tao, Shu; Wei, Siye; Zhang, Yanyan; Wang, Rong; Wang, Bin; Li, Wei; Shen, Huizhong; Huang, Ye; Chen, Yuanchen; Chen, Han; Yang, Yifeng; Wang, Wei; Wang, Xilong; Liu, Wenxin; Simonich, Staci L M

2012-07-17

93

Polycyclic aromatic hydrocarbon emission from straw burning and the influence of combustion parameters  

NASA Astrophysics Data System (ADS)

A simulated burning experiment was conducted in a tubular furnace system to examine the emission of polycyclic aromatic hydrocarbons (PAHs) from the burning of rice and bean straw, and the influence of combustion parameters was investigated. Total emission amounts of 16 PAHs (?PAHs) from the burning of rice and bean straw ranged from 9.29 to 23.6 ?g g -1 and from 3.13 to 49.9 ?g g -1, respectively, which increased with the increase of temperatures from 200 to 700 °C. The contribution of combustion to individual PAH yields was about 80.6-100%, which was generally increased with the increase of burning temperature. Moisture content in straw had a negative effect on PAH formation, especially on PAHs with low molecular weight. ?PAHs emission amounts decreased by 78.2% for bean straw with a moisture content of 30% in comparison with that for dried straw. In addition, PAH emission amounts increased with the increase of O 2 content in supplied air and then decreased, which showed a maximum emission at O 2 content of 40%. The source fingerprint of PAHs in emission from straw burning was established, which showed that naphthalene accounted for 35.0 ± 7.4% of ?PAHs. Based on the experimental data, emission amounts of ?PAHs from the burning of rice and bean straw were estimated to be 320-357 and 32.5-76.0 tons to ambient air per year in China, respectively.

Lu, Hao; Zhu, Lizhong; Zhu, Nali

94

Polycyclic aromatic hydrocarbons (PAHs) from coal combustion: emissions, analysis, and toxicology.  

PubMed

Coal may become more important as an energy source in the 21st century, and coal contains large quantities of organic and inorganic matter. When coal burns chemical and physical changes take place, and many toxic compounds are formed and emitted. Polycyclic aromatic hydrocarbons (PAHs) are among those compounds formed and are considered to pose potential health hazards because some PAHs are known carcinogens. Based on their toxicology, 16 PAHs are considered as priority pollutants by the USEPA. More attention must be given to the various methods of extraction and analysis of PAH from coal or coal products to accurately explain and determine the species of PAHs. The influences of the extraction time, solvents, and methods for PAH identification are important. In the future, more methods and influences will be studied more carefully and widely. PAHs are environmental pollutants, are highly lipid soluble, and can be absorbed by the lungs, gut, and skin of mammals because they are associated with fine particles from coal combustion. More attention is being given to PAHs because of their carcinogenic and mutagenic action. We suggest that when using a coal stove indoors, a chimney should be used; the particles and gas containing PAHs should be released outdoors to reduce the health hazard, especially in Southwest China. During coal utilization processes, such as coal combustion and pyrolysis, PAHs released may be divided into two categories according to their formation pathways: one pathway is derived from complex chemical reactions and the other is from free PAHs transferred from the original coal. The formation and emission of PAHs is a complex physical and chemical process that has received considerable attention in recent years. It is suggested that the formation mechanisms of PAHs will be an increasingly important topic for researchers to find methods for controlling emissions during coal combustion. PMID:18020302

Liu, Guijian; Niu, Zhiyuan; Van Niekerk, Daniel; Xue, Jian; Zheng, Liugen

2008-01-01

95

Distribution of polycyclic aromatic hydrocarbons in fly ash during coal and residual char combustion in a pressurized fluidized bed  

SciTech Connect

To investigate the distribution of polycyclic aromatic hydrocarbons (PAHs) in fly ash, the combustion of coal and residual char was performed in a pressurized spouted fluidized bed. After Soxhlet extraction and Kuderna-Danish (K-D) concentration, the contents of 16 PAHs recommended by the United States Environmental Protection Agency (U.S. EPA) in coal, residual char, and fly ash were analyzed by a high-performance liquid chromatography (HPLC) coupled with fluorescence and diode array detection. The experimental results show that the combustion efficiency is lower and the carbon content in fly ash is higher during coal pressurized combustion, compared to the residual char pressurized combustion at the pressure of 0.3 MPa. Under the same pressure, the PAH amounts in fly ash produced from residual char combustion are lower than that in fly ash produced from coal combustion. The total PAHs in fly ash produced from coal and residual char combustion are dominated by three- and four-ring PAHs. The amounts of PAHs in fly ash produced from residual char combustion increase and then decrease with the increase of pressure in a fluidized bed. 21 refs., 1 fig., 4 tabs.

Hongcang Zhou; Baosheng Jin; Rui Xiao; Zhaoping Zhong; Yaji Huang [Nanjing University of Information Science and Technology, Nanjing (China)

2009-04-15

96

Influence of surface chemistry on the adsorption of oxygenated hydrocarbons on activated carbons.  

PubMed

The objective of this work was to study the adsorption of different oxygenated hydrocarbons (methanol, ethanol, 1 and 2-butanol, methyl acetate) on activated carbons from organic mixtures with cyclohexane. Three activated carbons prepared by thermal and chemical treatments of a commercial carbon were employed for this purpose. Their textural properties were found to be similar, whereas their surface chemistries were modified, as shown by temperature-programmed desorption coupled to mass spectrometry (TPD-MS) and X-ray photoelectron spectroscopy (XPS). The adsorption isotherms were obtained by depletion method, and the analysis of adsorbed species was evaluated by TPD-MS to obtain new insight into the interactions between the different hydrocarbons and the carbon surface. Ethanol leads to a high-energy interaction between its hydroxyl function and the oxygenated surface groups and also to a lower energy interaction between the aliphatic part of the molecule and the carbon material. The desorption activation energy for this hydrophilic interaction is high (50 to 105 kJ/mol), and it is related to the nature of the carbon surface groups. The relative importance of these two interactions depend on the size of the alcohol/methanol is similar to ethanol, whereas butanols lead to more dispersive interactions. Methyl-acetate cannot undergo this kind of strong interaction and behaves like cyclohexane, having desorption activation energies ranging between 25 and 45 kJ/mol no matter the molecule and the carbon surface chemistry. PMID:21117633

Ghimbeu, Camelia Matei; Gadiou, Roger; Dentzer, Joseph; Schwartz, Dominique; Vix-Guterl, Cathie

2010-11-30

97

XPS analysis of combustion aerosols for chemical composition, surface chemistry, and carbon chemical state.  

PubMed

Carbonaceous aerosols can vary in elemental content, surface chemistry, and carbon nano-structure. Each of these properties is related to the details of soot formation. Fuel source, combustion process (affecting formation and growth conditions), and postcombustion exhaust where oxidation occurs all contribute to the physical structure and surface chemistry of soot. Traditionally such physical and chemical parameters have been measured separately by various techniques. Presented here is the unified measurement of these characteristics using X-ray photoelectron spectroscopy (XPS). In the present study, XPS is applied to combustion soot collected from a diesel engine (running biodiesel and pump-grade fuels); jet engine; and institutional, plant, and residential oil-fired boilers. Elemental composition is mapped by a survey scan over a broad energy range. Surface chemistry and carbon nanostructure are quantified by deconvolution of high-resolution scans over the C1s region. This combination of parameters forms a distinct matrix of identifiers for the soots from these sources. PMID:21322576

Vander Wal, Randy L; Bryg, Vicky M; Hays, Michael D

2011-02-15

98

Hydrocarbon-fuel\\/combustion-chamber-liner materials compatibility. Interim final report, 7 November 1986-31 October 1989  

Microsoft Academic Search

Results of material compatibility experiments using hydrocarbon fuels in contact with copper-based combustion chamber liner materials are presented. Mil-Spec RP-1, n- dodecane, propane, and methane fuels were tested in contact with OFHC, NASA-Z, and ZrCu coppers. Two distinct test methods were employed. Static tests, in which copper coupons were exposed to fuel for long durations at constant temperature and pressure,

Gage

1990-01-01

99

Thermodynamic and transport combustion properties of hydrocarbons with air. Part 2: Compositions corresponding to Kelvin temperature schedules in part 1  

SciTech Connect

The equilibrium compositions that correspond to the thermodynamic and transport combustion properties for a wide range of conditions for the reaction of hydrocarbons with air are presented. Initially 55 gaseous species and 3 coin condensed species were considered in the calculations. Only 17 of these 55 gaseous species had equilibrium mole fractions greater than 0.000005 for any of the conditions studied and therefore these were the only ones retained in the final tables.

Gordon, S.

1982-07-01

100

Effects of air\\/fuel combustion ratio on the polycyclic aromatic hydrocarbon content of carbonaceous soots from selected fuels  

Microsoft Academic Search

Patterns of polycyclic aromatic hydrocarbon (PAH) content were observed from GC\\/MS analysis of the extracts of soots at various air\\/fuel combustion ratios of three commonly used fuels: n-hexane, JP-8 (Jet fuel), and diesel. With increasing air\\/fuel ratio, from a simple diffusion flame up to an air\\/fuel ratio of 3.94, there is a significant loss of high molecular weight PAHs and

C. C. Jones; A. R. Chughtai; B. Murugaverl; D. M. Smith

2004-01-01

101

DNA ADDUCTS AS BIOMARKERS FOR ASSESSING EXPOSURE TO POLYCYCLIC AROMATIC HYDROCARBONS IN TISSUES FROM XUAN WEI WOMEN WITH HIGH EXPOSURE TO COAL COMBUSTION  

EPA Science Inventory

The high lung cancer raze in Xuan Wei, China, is associated with smoky coal use in unvented homes. moky coal combustion emits higher levels of polycyclic aromatic hydrocarbons (PAH) than wood combustion. his study used DNA adducts as a biomarker for human exposure to PAH from com...

102

Analysis and modeling of nitrous oxide chemistry in lean, premixed combustion  

SciTech Connect

A modeling study of N{sub 2}O chemistry in lean, premixed, atmospheric-pressure combustion is presented. Laminar flame and homogeneous combustion modeling calculations were performed using the PREMIX and CHEMKIN codes, respectively. Four systems containing H{sub 2}, O{sub 2}, Ar, and an N-containing dopant (NH{sub 3}, NO, or N{sub 2}O) were modeled and compared to recent flat-flame burner experiments. Agreement between measured and computed N{sub 2}O, NO, and N{sub 2} concentration profiles indicated that the model is a reasonable representation of the chemistry and transport in the flame system. The effects of assumed burner temperature, temperature profile shape, mass diffusion, and probing are investigated. A sensitivity analysis of the flame calculations is presented. For cases where burner temperatures were identical but temperatures were either determined by solving the energy equation numerically or were specified to be equivalent to measured temperatures, calculated N{sub 2}O, NO, and N{sub 2} profiles differed by 2%-15%. Calculations that differed only in specified flameholder surface temperature (400-1000 K) produced concentration profiles that varied by approximately 20% in NO and N{sub 2} and by as much as a factor of 7 in N{sub 2}O.

Martin, R.J.; Brown, N.J. (Applied Science Div., Lawrence Berkeley Lab., Berkeley, CA (US))

1990-12-01

103

Thermal chemistry of C4 hydrocarbons on Pt(111): Mechanism for double-bond isomerization.  

PubMed

The thermal chemistry of a number of C4 hydrocarbons (1,3-butadiene, 1-bromo-3-butene, 1-bromo-2-butene, trans-2-butene, cis-2-butene, 1-butene, 2-iodobutane, 1-iodobutane, and butane) was investigated on clean and hydrogen- and deuterium-predosed Pt(111) single-crystal surfaces by temperature-programmed desorption and reflection-absorption infrared spectroscopy. A combination of rapid beta-hydride eliminations from alkyls to olefins and the reverse insertions of those olefins into metal-hydrogen bonds explains the hydrogenation, dehydrogenation, and H-D exchange products that desorb from the surface. A preference for hydrogenation at the end carbons and dehydrogenation from the inner carbons also explains the extent of the isotope exchange and the preferential isomerization of 1-butene to 2-butene observed on this Pt(111) surface. The reactions of more dehydrogenated C4 species is also discussed. PMID:16851283

Lee, Ilkeun; Zaera, Francisco

2005-02-24

104

Effect of Two-Stage Injection on Unburned Hydrocarbon and Carbon Monoxide Emissions in Smokeless Low-Temperature Diesel Combustion with UltraHigh Exhaust Gas Recirculation  

Microsoft Academic Search

The unburned hydrocarbon (UHC) and carbon monoxide (CO) emissions from smokeless low-temperature diesel combustion (LTC) with ultra-high exhaust gas recirculation (EGR) can be attributed to lowered combustion temperatures as well as to under-mixing of fuel-rich mixture along the combustion chamber walls, overly mixed fuel-lean mixture at the spray tails, and fuel missing the piston bowl and entering the squish zones.

T Li; M Suzuki; H Ogawa

2010-01-01

105

An integrated aerodynamic-ramp-injector/plasma-torch-igniter for supersonic combustion applications with hydrocarbon fuels  

NASA Astrophysics Data System (ADS)

The first integrated, flush-wall, aero-ramp-fuel-injector/plasma-torch igniter and flame propagation system for supersonic combustion applications with hydrocarbon fuels was developed and tested. The main goal of this project was to develop a device which could be used to demonstrate that the correct placement of a plasma-torch-igniter/flame-holder in the wake of the fuel jets of an aero-ramp injector array could make sustained, efficient supersonic combustion with low losses and thermal loading possible in a high enthalpy environment. The first phase of the research effort was conducted at Mach 3.0 at a static pressure and temperature of 0.19 atm and 101 K. This phase involved component analyses to improve on the designs of the aero-ramp and plasma-torch as well as address integration and incorporation difficulties. The information learned from these experiments lead to the creation of the first prototype integrated aero-ramp/plasma torch design featuring a new simplified four-hole aero-ramp design. The second phase of the project consisted of experiments at Mach 2.4 involving a cold-flow mixing evaluation of the new aero-ramp design and a resizing of the device for incorporation into a scramjet flow path test rig at the Air Force Research Laboratories (AFRL). Experiments were performed at a static pressure and temperature of 0.25 atm and 131 K, and at injector-jet to freestream momentum flux ratios ranging from 1.0 to 3.3. Results showed the aero-ramp to mix at a considerably faster rate than the injector used in the AFRL baseline combustor configuration due to high levels of vorticity created by the injector array. The last phase of the research involved testing the final device design in a cold-flow environment at Mach 2.4 with ethylene fuel injection and an operational plasma torch with methane, nitrogen, a 90-percent nitrogen 10-percent hydrogen (by volume) mixture, and air feedstock gases. Experiments were performed with injector jet to freestream momentum flux ratios ranging from 1.4 to 3.3, and 1.2 with the plasma torch at a nominal power level 2000 watts. Overall, the final integrated design showed a high mixing efficiency and a higher potential for repeatable main fuel ignition and flame propagation with the plasma torch placed at the middle of the three downstream torch stations tested ( x/dinjector = 8 downstream from the center of the injector area), with nitrogen as the torch feedstock. (Abstract shortened by UMI.)

Jacobsen, Lance Steven

106

Non-volatile Hydrocarbon Chemistry Studies Around a Production Platform on Australia's Northwest Shelf  

NASA Astrophysics Data System (ADS)

In September 1994 and 1995, scientists from the Australian Institute of Marine Science (AIMS) and the Australian Geological Survey Organization (AGSO) conducted surveys aboard the RV Lady Basten to determine the dispersion, fates and effects of produced formation water (PFW) discharged from the ' Harriet A ' oil production platform near the Montebello Islands. This report is one of four related papers and describes the non-volatile hydrocarbon chemistry studies. The dispersion of the PFW into dissolved and particulate fractions of seawater were measured using moored high volume water samplers, surface screen samplers and moored and drifting sediment traps. Bio-accumulation was studied using transplanted oysters, and dispersion measured into sediment with benthic grabs. Results showed enrichment in non-volatile hydrocarbons in surface microlayer samples to a distance of 1·8 km in the direction of tidal flow. Concentrations in surface microlayers near the platform varied by an order of magnitude and corresponded to when a surface slick was visible or not visible. Concentrations of oil in seawater ranged from 2·0 to 8·5 ?g l -1at near stations to 1·3 ?g l -1at 1·8 km. Water column samples showed the processes of desorption from particles for soluble components occur within the range of 1·8 km. Most particulate hydrocarbons drop out of suspension within c. 1 to 2 km from the platform. Fluxes of particulate hydrocarbons through the water column at c. 1 km, as estimated by moored sediment traps in 1995, were 138 to 148 ng cm -2day -1. A decrease in sediment concentrations within c. 1 km of the platform was measured as 2·45±1·29 ?g g -1dry wt (n=15) in 1994 to 0·86±0·54 ?g g -1dry wt (n=21) in 1995, after the platform installed a centrifugal separator in the discharge treatment process. Thus the residence time of this relatively low molecular weight oil was estimated in the coarse aerobic sands surrounding the platform to be less than one year. Oysters suspended near the platform bio-accumulated hydrocarbons and other lipophilic organics in their tissues. Uptake rates and bio-concentration factors of hydrocarbons indicated potential toxicity at the near-field stations within c. 1 km radius. A mass balance was constructed to show the partitioning of the input of hydrocarbons from the PFW into the surrounding marine ecosystem. The rates of dissipation processes were estimated as follows: dilution from tidal currents>degradation in the water column>sedimentation>evaporation. The calculations based on maximum concentrations measured in the environmental samples accounted for 85% of the daily input suspended within a 1 km radius. It is estimated that the potential zone of toxic influence in the water column extends to a distance of approximately 1 km. Concentrations of oil in sediments were too low to indicate potential toxicity. By the collaborative application of oceanographic and geochemical techniques to marine environmental problems, we endeavour to provide effective feedback to the oil industry to gauge the effectiveness of their operational strategies in minimizing impact in these pristine regions.

Burns, K. A.; Codi, S.

1999-12-01

107

Modeling of Spherically Symmetric Droplet Flames Including Complex Chemistry: Effect of Water Addition on n-Heptane Droplet Combustion  

Microsoft Academic Search

A spherically symmetric quasi-steady model has been formulated for droplet combustion which includes complex chemistry and variable properties. The model is applied to mixtures of heptane and water.Calculations from the model show that the acetylene concentration inside a heptane flame increases with increasing droplet diameter. This trend suggests an increased propensity for soot formation with increasing droplet diameter which is

G. S. JACKSON; C. T. AVEDISIAN

1996-01-01

108

Development of Atmospheric Chemistry-Aerosol Transport Model for Bioavailable Iron From Dust and Combustion Source  

NASA Astrophysics Data System (ADS)

An accurate prediction of bioavailable iron fraction for ocean biota is hampered by uncertainties in modeling soluble iron fractions in atmospheric aerosols. It has been proposed that atmospheric processing of mineral aerosols by anthropogenic pollutants may be a key pathway to transform insoluble iron into soluble forms. The dissolution of dust minerals strongly depends on solution pH, which is sensitive to the heterogeneous uptake of soluble gases by the dust particle. Due to the complexity, previous model assessments generally use a common assumption in thermodynamical equilibrium between gas and aerosol phases. Here, we compiled an emission inventory of iron from combustion and dust source, and incorporated a dust iron dissolution scheme in a global chemistry-aerosol transport model (IMPACT). We will examine and discuss the uncertainties in estimation of dissolved iron as well as comparisons of the model results with available observations.

Ito, A.; Feng, Y.

2009-12-01

109

Emission factors and particulate matter size distribution of polycyclic aromatic hydrocarbons from residential coal combustions in rural Northern China  

NASA Astrophysics Data System (ADS)

Coal consumption is one important contributor to energy production, and is regarded as one of the most important sources of air pollutants that have considerable impacts on human health and climate change. Emissions of polycyclic aromatic hydrocarbons (PAHs) from coal combustion were studied in a typical stove. Emission factors (EFs) of 16 EPA priority PAHs from tested coals ranged from 6.25 ± 1.16 mg kg -1 (anthracite) to 253 ± 170 mg kg -1 (bituminous), with NAP and PHE dominated in gaseous and particulate phases, respectively. Size distributions of particulate phase PAHs from tested coals showed that they were mostly associated with particulate matter (PM) with size either between 0.7 and 2.1 ?m or less than 0.4 ?m (PM 0.4). In the latter category, not only were more PAHs present in PM 0.4, but also contained higher fractions of high molecular weight PAHs. Generally, there were more than 89% of total particulate phase PAHs associated with PM 2.5. Gas-particle partitioning of freshly emitted PAHs from residential coal combustions were thought to be mainly controlled by absorption rather than adsorption, which is similar to those from other sources. Besides, the influence of fuel properties and combustion conditions was further investigated by using stepwise regression analysis, which indicated that almost 57 ± 10% of total variations in PAH EFs can be accounted for by moisture and volatile matter content of coal in residential combustion.

Shen, Guofeng; Wang, Wei; Yang, Yifeng; Zhu, Chen; Min, Yujia; Xue, Miao; Ding, Junnan; Li, Wei; Wang, Bin; Shen, Huizhong; Wang, Rong; Wang, Xilong; Tao, Shu

2010-12-01

111

Impact of reactive nitrogen emissions from fossil fuel combustion and biomass burning on atmospheric chemistry  

SciTech Connect

The increasing desire for energy in our society has caused changes in our environment. One of the byproducts of energy consumption is the emission of nitrogen oxides from combustion processes. Nitrogen oxides play an important role in atmospheric chemistry on local, regional, and global scales. They are considered primary pollutants which can chemically react and contribute to photochemical smog. They are also precursors to the chemical formation of nitric acid (HNO{sub 3}). Nitric acid is a major contributor to acidic deposition, more commonly referred to as acid rain.'' Reactive nitrogen is also a major limiting nutrient in some soil and ocean ecosystems. NO{sub x} is also important because it interacts with other trace gases in the atmosphere. In this study, using a Lagrangian chemical-transport-deposition model adapted to the nitrogen cycle, we will look at all of the known sources, both natural and man-made. We will attempt to quantify the relative affect that man-made sources including fossil fuel and biomass burning have had on the nitrogen cycle and the chemistry of the atmosphere throughout the globe. 50 refs., 9 figs., 1 tab.

Dignon, J.; Penner, J.E.; Atherton, C.S.; Walton, J.J.

1991-07-01

112

UV induced Chemistry of Polycyclic Aromatic Hydrocarbons in NH_3-containing Interstellar Ice Analogues  

NASA Astrophysics Data System (ADS)

Polycyclic Aromatic Hydrocarbons are expected to be widely present in the interstellar medium. For the typical temperatures in space, they will freeze out on icy dust grains, like other species, such as water and ammonia. Optical spectra of PAHs in water ice have become available recently using a new setup at Leiden (OASIS - Optical Absorption Setup for Ice Spectroscopy). This setup allows to study the time resolved PAH and PAH photoproduct behavior upon hard UV photolysis, evidencing an active PAH chemistry in the ice for temperatures in the 15-150 K regime. The matrix surrounding turns out to be very important. As an extension of the previous PAH:H2O ices, here the first results are presented for UV irradiated PAH:NH3 and PAH:NH3/H2O ices. In this way PAH destruction and molecule formation can be monitored in situ and on line. It is found that whereas H2O ices particularly result in the formation of PAH-cations, ammonia seems to favor the formation of anions in the ice. After photolysis is stopped, the PAH anion signal vanishes. At this stage these results are interpreted by assuming that charged species form in interstellar ice by electron transfer from ammonia photoproducts, rather than acid-base proton transfer.

Cuylle, S. H.; Tenenbaum, E. D.; Bouwman, J.; Linnartz, H.

2011-05-01

113

Polycyclic aromatic hydrocarbon size distributions in aerosols from appliances of residential wood combustion as determined by direct thermal desorption—GC\\/MS  

Microsoft Academic Search

In this work, a direct thermal desorption\\/gas chromatography\\/mass spectrometry (TD\\/GC\\/MS) method is implemented to determine the polycyclic aromatic hydrocarbon (PAH) composition (MW=202–302amu) in size-segregated aerosols from residential wood combustion. Six combustion tests are performed with two commonly burned wood fuel species, Douglas-fir (Pseudotsuga sp.) and white oak (Quercus sp.). Atmospheric dilution and cooling of the aerosol plume are simulated in

Michael D. Hays; N. Dean Smith; John Kinsey; Yuanji Dong; Peter Kariher

2003-01-01

114

Assembling gas-phase reaction mechanisms for high temperature inorganic systems based on quantum chemistry calculations and reaction rate theories  

Microsoft Academic Search

Detailed chemical kinetic modeling based on computational quantum chemistry has been quite successful in making quantitative predictions about some systems, particularly the combustion of small hydrocarbons and certain areas of atmospheric chemistry. The gas phase chemistry of many processes in high-temperature inorganic systems, from materials synthesis to propulsion to waste incineration, could in principle be modeled with equal or greater

Mark T. Swihart

2005-01-01

115

Some aspects of hydrocarbon activation on platinum group metal combustion catalysts  

Microsoft Academic Search

The activation of different hydrocarbons on Pt and Pd catalysts has been investigated. The role of different forms of surface oxygen, and an explanation for the unusual order of activity (methane > ethane) is presented.

R. Burch; P. K. Loader; F. J. Urbano

1996-01-01

116

Nonmethane hydrocarbons at Pico Mountain, Azores: 1. Oxidation chemistry in the North Atlantic region  

NASA Astrophysics Data System (ADS)

Measurements of nonmethane hydrocarbons (NMHC) at the Pico Mountain observatory at 2225 m asl on Pico Island, Azores, Portugal, from August 2004 to August 2005 (in part overlapping with the field campaign of the International Consortium on Atmospheric Research on Transport and Transformation study) were used to investigate NMHC sources and seasonal oxidation chemistry in the central North Atlantic region. Levels of anthropogenic NMHC were characteristic of the marine free troposphere. Their concentrations were low compared to continental sites at higher northern latitudes, but higher than data reported from a similarly located Pacific mountain site at Mauna Loa Observatory, Hawaii. These higher NMHC levels are indicative of a greater influence of the adjacent continents on air composition at Pico. Substantially enhanced NMHC concentrations during the summers of 2004 and 2005 were attributed to long-range transport of biomass burning plumes originating from fires in northern Canada, Alaska, and Siberia. This finding exemplifies the continuing impact of biomass burning plumes on atmospheric composition and chemistry many days downwind of these emission sources. Seasonal cycles with lower NMHC concentrations and lower ratios of more reactive to less reactive NMHC during summer reflect the higher degree of photochemical processing occurring during transport. The NMHC concentrations indicate no significant role of chlorine atom oxidation on NMHC. Ozone above 35 ppbv was measured at Pico Mountain throughout all seasons. Enhanced ozone levels were observed in air that had relatively "fresh" photochemical signatures (e.g., ln [propane]/[ethane] > -2.5). During spring-summer air that was more processed ("older" air with ln [propane]/[ethane] < -2.5) on average had lower ozone levels (down to <20 ppbv). This relationship indicates that conditions in the lower free troposphere over the mid-North Atlantic during the spring and summer lead to net photochemical ozone destruction while air is photochemically aging during transport to Pico. This behavior contrasts to that in the mid-North Pacific where other recent studies have found that the photochemistry is more nearly ozone neutral.

Helmig, D.; Tanner, D. M.; Honrath, R. E.; Owen, R. C.; Parrish, D. D.

2008-10-01

117

PIC formation during the combustion of simple hydrocarbons in inhomogeneous incineration systems  

Microsoft Academic Search

The formation of products of incomplete combustion (PICs) during incineration processes strongly depends on the influence of mixing on the instantaneous values of the reactant concentrations and the temperature in the combustion chamber. Experiments were performed to illustrate the influence of tur- bulence intensity on PIC formation in a turbulent plug flow reactor, where C2H4 was injected into an oxygen-rich,

Carlo Procaccini; Markus Kraft; Harald Fey; Henning Bockhorn; John P. Longwell; Adel F. Sarofim; Kenneth A. Smith

1998-01-01

118

Hydrocarbon  

NASA Astrophysics Data System (ADS)

Gas hydrates in permafrost regions are believed to be a significant high-latitude reservoir for hydrocarbon gases, including methane which is a ``greenhouse" gas that may play a significant role in global climate warming. Melting permafrost and associated gas hydrates may contribute hydrocarbon ``greenhouse" gases to the atmosphere, however, little is known about the composition or distribution of the natural gases within permafrost. The primary objective of this presentation is to document and compare the composition and source of the hydrocarbon gases associated with gas hydrates both within and immediately below the zone of permafrost in the Prudhoe Bay-Kuparuk River area of northern Alaska. This study included two major geochemical sampling programs in northern Alaska. In the first program the in-situ composition of the gas within and below the zone of permafrost in the Prudhoe Bay-Kuparuk River area was determined, and in the second, a series of surficial geochemical surveys were made over the area of known surficial gas seepage. Geochemical analyses of drill cuttings collected from 11 petroleum industry wells indicate that methane is the principal hydrocarbon gas in the near-surface (0-1,500 m) strata of the North Slope. Stable methane-carbon isotopic analyses of gaseous drill cuttings from several wells suggest that the methane within the permafrost zone is from both microbial and thermogenic sources. To further examine shallow subsurface gas migration and potential atmospheric methane fluxes from permafrost regions, we analyzed the molecular and methane-carbon isotopic composition of the gas from 105 shallow (<2 m) permafrost cores collected across the Eileen fault zone, an area of known surficial gas seepage and more deeply buried gas hydrate occurrence in the Prudhoe Bay-Kuparuk River area. Analyses of these samples yielded high concentrations of methane and other hydrocarbon gases over the surface trace of the Eileen fault zone. Isotopic analysis of methane in the samples collected near the main fault yielded evidence of thermogenic gas. The data from shallow cores, together with the subsurface geochemical data obtained from northern Alaska, confirm that permafrost does control the distribution, volume, and composition of hydrocarbon gases in Arctic regions. In some areas the hydrocarbon gases in ice-bonded permafrost are exclusively microbial in origin, whereas thermogenic gases only occur beneath the ice-bonded interval. In such cases the base of ice-bonded permafrost may act as a trap for free gas accumulations. In other areas, where unique geologic conditions such as faulting occur, thermogenic gases originating from deep hydrocarbon reservoirs may occur within permafrost even at shallow depths. The abundance of both microbial- and thermogenic-sourced gases and their apparent mobility suggests that the melting of permafrost and associated gas hydrate accumulations could release significant volumes of hydrocarbon ``greenhouse" gases to the atmosphere.

Collett, T. S.; Lorenson, T. D.

2005-12-01

119

Initiation mechanisms and kinetics of pyrolysis and combustion of JP-10 hydrocarbon jet fuel.  

PubMed

In order to investigate the initiation mechanisms and kinetics associated with the pyrolysis of JP-10 (exo-tricyclo[5.2.1.0(2,6)]decane), a single-component hydrocarbon jet fuel, we carried out molecular dynamics (MD) simulations employing the ReaxFF reactive force field. We found that the primary decomposition reactions involve either (1) dissociation of ethylene from JP-10, resulting in the formation of a C(8) hydrocarbon intermediate, or (2) the production of two C(5) hydrocarbons. ReaxFF MD leads to good agreement with experiment for the product distribution as a function of temperature. On the basis of the rate of consumption of JP-10, we calculate an activation energy of 58.4 kcal/mol for the thermal decomposition of this material, which is consistent with a strain-facilitated C-C bond cleavage mechanism in JP-10. This compares well with the experimental value of 62.4 kcal/mol. In addition, we carried out ReaxFF MD studies of the reactive events responsible for oxidation of JP-10. Here we found overall agreement between the thermodynamic energies obtained from ReaxFF and quantum-mechanical calculations, illustrating the usefulness of ReaxFF for studying oxidation of hydrocarbons. The agreement of these results with available experimental observations demonstrates that ReaxFF can provide useful insights into the complicated thermal decomposition and oxidation processes of important hydrocarbon fuels. PMID:19209880

Chenoweth, Kimberly; van Duin, Adri C T; Dasgupta, Siddharth; Goddard, William A

2009-03-01

120

The activation of hydrocarbon C-H bonds over transition metal oxide catalysts: A FTIR study of hydrocarbon catalytic combustion over MgCr{sub 2}O{sub 4}  

SciTech Connect

The interaction of light hydrocarbons (methane, ethane, propane, propene, n-butane, isobutane, 1-butene, benzene, and toluene) with the oxidized surface of the spinel MgCr{sub 2}O{sub 4} (an active hydrocarbon combustion catalyst) has been investigated by FTIR spectroscopy in the temperature range 300-773 K. This interaction results in the reduction of the catalyst and the production of oxygen-containing adsorbed species. These species have been identified by comparison with the spectra of oxygen-containing species (alcohols, aldehydes, ketones, carboxylic acids, carbon oxides) directly adsorbed on the surface. It has been concluded that every hydrocarbon reacts at its weakest C-H bond on Cr{sup n+}=O (n = 5 or 6) surface sites giving rise by hydrogen abstraction and C-O bond formation to alkoxy groups. These species are further oxidized to carbonyl compounds and/or carboxylate anions and, finally, carbon oxides. The earlier intermediates (alkoxides, carbonyl compounds) are detectable only with the most reactive hydrocarbons (propane, n-butane, isobutane, propene, 1-butene, toluene), while with the least reactive hydrocarbons (methane and benzene), because of their two high activation temperature, only the final intermediates are detectable (carbonates, carboxylates). Molecular-level mechanism for C-H cleavage and hydrocarbon catalytic combustion are proposed. 47 refs., 11 figs., 1 tab.

Finnocchio, E.; Busca, G.; Lorenzelli, V. [Universita P.le Kennedy, Geneva (Italy); Willey, R.J. [Northeastern Univ., Boston, MA (United States)

1995-01-01

121

Chemical Kinetic Models for Combustion of Hydrocarbons and Formation of Nitric Oxide.  

National Technical Information Service (NTIS)

The formation of nitrogen oxides NOx during combustion of methane, propane, and a jet fuel, JP-4, was investigated in a jet stirred combustor. The results of the experiments were interpreted using reaction models in which the nitric oxide (NO) forming rea...

C. J. Jachimowski C. H. Wilson

1980-01-01

122

Effect of fuel nitrogen and hydrogen content on emissions in hydrocarbon combustion  

Microsoft Academic Search

This paper presents the results of an investigation of the effect of operating conditions and fuel properties on emissions for the two-stage combustion of fuels with significant organic nitrogen content. This is a basic research effort in support of DOE's Advanced Power Systems Program, a development program to adapt ground-power gas turbines to use coal derived fuels. The present paper

D. A. Bittker; G. Wolfbrandt

1980-01-01

123

Chemical characterization and stable carbon isotopic composition of particulate polycyclic aromatic hydrocarbons issued from combustion of 10 Mediterranean woods  

NASA Astrophysics Data System (ADS)

The objectives of this study were to characterize polycyclic aromatic hydrocarbons from particulate matter emitted during wood combustion and to determine, for the first time, the isotopic signature of PAHs from nine wood species and Moroccan coal from the Mediterranean Basin. In order to differentiate sources of particulate-PAHs, molecular and isotopic measurements of PAHs were performed on the set of wood samples for a large panel of compounds. Molecular profiles and diagnostic ratios were measured by gas chromatography coupled with a mass spectrometer (GC/MS) and molecular isotopic compositions (?13C) of particulate-PAHs were determined by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). Wood species present similar molecular profiles with benz(a)anthracene and chrysene as dominant PAHs, whereas levels of concentrations range from 1.8 to 11.4 mg g-1 OC (sum of PAHs). Diagnostic ratios are consistent with reference ratios from literature but are not sufficient to differentiate the different species of woods. Concerning isotopic methodology, PAH molecular isotopic compositions are specific for each species and contrary to molecular fingerprints, significant variations of ?13C are observed for the panel of PAHs. This work allows differentiating wood combustion from others origins of particulate matter (vehicular exhaust) using isotopic measurements (with ?13CPAH = -28.7 to -26.6‰) but also confirms the necessity to investigate source characterisation at the emission in order to help and complete source assessment models. These first results on woodburnings will be useful for the isotopic approach of source tracking.

Guillon, A.; Le Ménach, K.; Flaud, P.-M.; Marchand, N.; Budzinski, H.; Villenave, E.

2012-08-01

124

Polycyclic aromatic hydrocarbons in coal combustion flue gas under electron beam irradiation  

Microsoft Academic Search

The electron beam (EB) technology has been investigated as a one-stage multi-component purification technology. The initial concentrations of SO2, NOx, and 16 polycyclic aromatic hydrocarbons (PAH) in flue gas have been reduced simultaneously by over 60%, 50%, and 20%, respectively, in flue gas at the dose of 8kGy. Determined PAH distribution in the by-product has shown negligible role of adsorption

Anna Ostapczuk; Janusz Licki; Andrzej G. Chmielewski

2008-01-01

125

Hydrocarbon-fuel\\/combustion-chamber-liner materials compatibility. Final Report, 31 Oct. 1989 - 31 Mar. 1991  

Microsoft Academic Search

The results of dynamic tests using methane and NASA-Z copper test specimen under conditions that simulate those expected in the cooling channels of a regeneratively cooled LOX\\/hydrocarbon booster engine operating at chamber pressures up to 3000 psi are presented. Methane with less than 0.5 ppm sulfur contamination has little or no effect on cooling channel performance. At higher sulfur concentrations,

Homer

1991-01-01

126

Photostability of nitro-polycyclic aromatic hydrocarbons on combustion soot particles in sunlight  

Microsoft Academic Search

Little is known about the stability of nitro-polycyclic aromatic hydrocarbons (NPAH) on atmospheric aerosols. In this study, the photostability of particle-associated NPAH was investigated under natural sunlight. Deuterated and native NPAH along with diesel exhaust or wood smoke particles were added to a 190-m³ outdoor smog chamber and permitted to age under sunlight in cold and warm temperatures. Ozone (Oâ),

Zhihua Fan; Richard M. Kamens; Jianxin Hu; Jianbo Zhang; Stephen McDow

1996-01-01

127

Structural characteristics of polycyclic aromatic hydrocarbon isomers in coal tars and combustion products  

Microsoft Academic Search

Isomeric polycyclic aromatic hydrocarbons (PAH) with two to six rings in coal-derived products and in a carbon black were separated, identified, and quantified by using capillary column gas chromatography and gas chromatography-mass spectrometry. A newly synthesized smectic liquid-crystalline polysiloxane and a conventional polymethylsiloxane were utilized as stationary phases. Many previously difficult to separate isomeric PAH (i.e., methylphenanthrenes\\/methylanthracenes, triphenylene\\/chrysene, methylchrysenes, benzofluoranthenes,

Masaharu Nishioka; Huey Ching Chang; Milton L. Lee

1986-01-01

128

Hydrocarbon-ammonia moulding-a new technology for production of combustion catalysts  

Microsoft Academic Search

Fluidized bed catalytic combustion has proved to be very promising for industrial application. The milestone problem is development\\u000a of support and catalyst with high mechanical and thermal stability. We have developed a new technology for production of alumina\\u000a supports with desired spherical shape, texture and structure. Properties of spherical granules depend on the method of granulation\\u000a and most attention has

Zinfer R. Ismagilov; R. A. Shkrabina; Natalia A. Koryabkina

1997-01-01

129

Investigation of chlorine radical chemistry in the Eyjafjallajökull volcanic plume using observed depletions in non-methane hydrocarbons  

NASA Astrophysics Data System (ADS)

As part of the effort to understand volcanic plume composition and chemistry during the eruption of the Icelandic volcano Eyjafjallajökull, the CARIBIC atmospheric observatory was deployed for three special science flights aboard a Lufthansa passenger aircraft. Measurements made during these flights included the collection of whole air samples, which were analyzed for non-methane hydrocarbons (NMHCs). Hydrocarbon concentrations in plume samples were found to be reduced to levels below background, with relative depletions characteristic of reaction with chlorine radicals (Cl). Recent observations of halogen oxides in volcanic plumes provide evidence for halogen radical chemistry, but quantitative data for free halogen radical concentrations in volcanic plumes were absent. Here we present the first observation-based calculations of Cl radical concentrations in volcanic plumes, estimated from observed NMHC depletions. Inferred Cl concentrations were between 1.3 × 104 and 6.6 × 104 Cl cm-3. The relationship between NMHC variability and local lifetimes was used to investigate the ratio between OH and Cl within the plume, with [OH]/[Cl] estimated to be ˜37.

Baker, Angela K.; Rauthe-Schöch, Armin; Schuck, Tanja J.; Brenninkmeijer, Carl A. M.; van Velthoven, Peter F. J.; Wisher, Adam; Oram, David E.

2011-07-01

130

Positive-Ion Chemistry: High Yields of Heavy Hydrocarbons from Solid Methane by Ionizing Radiation  

Microsoft Academic Search

At 77circK solid methane is polymerized rapidly and efficiently to heavy hydrocarbons by cobalt-60 gamma rays. The product is a viscous oil consisting mainly of saturated and highly branched hydrocarbons containing an average of about 20 carbon atoms per molecule. This would seem to be evidence for positive-ion chemical reactions in the solid state analogous to those previously reported to

Donald R. Davis; W. F. Libby

1964-01-01

131

Solid-state {sup 13}C MAS NMR study of methanol-to-hydrocarbon chemistry over H-SAPO-34  

SciTech Connect

{sup 13}C solid-state MAS NMR was used to probe the chemistry of a number of species involved in the methanol-to-hydrocarbon process over H-SAPO-34 molecular sieve at both high (573 K) and low (473-563 K) temperature ranges and at very low conversion (<0.1%). Isobutane was the only hydrocarbon product observed at 473 and 573 K. Evidence for the operation of a stepwise methylation reaction via surface-bound species derives from, first, the treatment of several samples with different loadings of methanol at 523-563 K and, second, when either [{sup 13}C]methanol is coadsorbed with [{sup 12}C]ethene over the catalyst or [{sup 12}C]ethene is reacted with pre-[{sup 13}C]methylated SAPO-34. The hydrocarbon products in these experiments were mainly isobutane and isopentane as well as methane, ethene, and propane. Based on these experimental findings, a number of mechanistic approaches concerning the very first stages of the reaction are discussed. 56 refs., 13 figs., 3 tabs.

Salehirad, F.; Anderson, M.A. [UMIST, Manchester (United Kingdom)

1996-12-01

132

Polycyclic aromatic hydrocarbons in coal combustion flue gas under electron beam irradiation  

NASA Astrophysics Data System (ADS)

The electron beam (EB) technology has been investigated as a one-stage multi-component purification technology. The initial concentrations of SO2, NOx, and 16 polycyclic aromatic hydrocarbons (PAH) in flue gas have been reduced simultaneously by over 60%, 50%, and 20%, respectively, in flue gas at the dose of 8 kGy. Determined PAH distribution in the by-product has shown negligible role of adsorption in PAH removal. PAH-based overall toxicity of flue gas decreased remarkably in the range of 30-80% under EB irradiation.

Ostapczuk, Anna; Licki, Janusz; Chmielewski, Andrzej G.

2008-04-01

133

Combustion-Derived Hydrocarbons Localize to Lipid Droplets in Respiratory Cells  

Microsoft Academic Search

adipocytes, support the accumulation of PAHs within lipid droplets. Microarray data revealed up-regulation of aryl hydrocarbon recep- tor-induced Phase I biotransformation enzymes and nuclear ery- throid-2 related factor 2-mediated oxidative stress responses in BEAS-2B cells. Quantitative RT-PCR results confirmed a time-de- pendent up-regulation of Phase I biotransformation enzymes (CYP1A1, CYP1B1, and ALDH3A1) in BDS-exposed BEAS-2B and MH-S cells. Thus, respiratory

Gleeson Murphy; Rodney L. Rouse; William W. Polk; William G. Henk; Steven A. Barker; Marc J. Boudreaux; Z. Elizabeth Floyd; Arthur L. Penn

134

Diazido alkanes and diazido alkanols as combustion modifiers for liquid hydrocarbon ramjet fuels  

SciTech Connect

A liquid hydrocarbon ramjet fuel is described comprising from more than zero to 100 weight percent of a diazido alkanol of the general formula N/sub 3/CH/sub 2/(CH/sub 2/)/sub chi/CHOH(CH/sub 2/)/sub y/CH/sub 2/N/sub 3/ wherein chi is an integer of from 0 to 9, y is an integer of from 0 to 19, chi+y is an integer of from 0 to 19, and chiless than or equal toy, and the balance being a conventional jet fuel.

Miller, R.S.; Moriarty, R.M.; Law, C.K.

1988-05-03

135

Determination of the Heat of Combustion of Biodiesel Using Bomb Calorimetry: A Multidisciplinary Undergraduate Chemistry Experiment  

ERIC Educational Resources Information Center

|Biodiesel was synthesized by transesterification of waste vegetable oil using common glassware and reagents, and characterized by measuring heat of combustion, cloud point, density and measuring the heat of combustion and density together allows the student the energy density of the fuel. Analyzing the biodiesel can serve as a challenging and…

Akers, Stephen M.; Conkle, Jeremy L.; Thomas, Stephanie N.; Rider, Keith B.

2006-01-01

136

Thermal decomposition of selected chlorinated hydrocarbons during gas combustion in fluidized bed  

PubMed Central

Background The process of thermal decomposition of dichloromethane (DCM) and chlorobenzene (MCB) during the combustion in an inert, bubbling fluidized bed, supported by LPG as auxiliary fuel, have been studied. The concentration profiles of C6H5CI, CH2Cl2, CO2, CO, NOx, COCl2, CHCl3, CH3Cl, C2H2, C6H6, CH4 in the flue gases were specified versus mean bed temperature. Results The role of preheating of gaseous mixture in fluidized bed prior to its ignition inside bubbles was identified as important factor for increase the degree of conversion of DCM and MCB in low bed temperature, in comparison to similar process in the tubular reactor. Conclusions Taking into account possible combustion mechanisms, it was identified that autoignition in bubbles rather than flame propagation between bubbles is needed to achieve complete destruction of DCM and MCB. These condition occurs above 900°C causing the degree of conversion of chlorine compounds of 92-100%.

2013-01-01

137

Structural characteristics of polycyclic aromatic hydrocarbon isomers in coal tars and combustion products  

SciTech Connect

Isomeric polycyclic aromatic hydrocarbons (PAH) with two to six rings in coal-derived products and in a carbon black were separated, identified, and quantified by using capillary column gas chromatography and gas chromatography-mass spectrometry. A newly synthesized smectic liquid-crystalline polysiloxane and a conventional polymethylsiloxane were utilized as stationary phases. Many previously difficult to separate isomeric PAH (i.e., methylphenanthrenes/methylanthracenes, triphenylene/chrysene, methylchrysenes, benzofluoranthenes, and pentaphene/benzo(b)chrysene) were identified). The relative abundances of the PAH in these samples were compared and correlated to the reaction conditions during their production. The relationship between abundance and structure for the identified PAH was also discussed. 26 references, 5 figures, 1 table.

Nishioka, M.; Chang, H.C.; Lee, M.L.

1986-10-01

138

Fundamental combustion research applied to pollution formation. Volume 2b. Physics and chemistry of two-phase systems: devolatilization and volatile reactions  

Microsoft Academic Search

The reports included in the three-part volume describe eight studies by various investigators, to better understand the physics and chemistry of two-phase combustion with respect to pollution formation. Volume IIb gives information on the influence of various combustion parameters (i.e., fuel type, stoichiometry, residence time, temperature, and mixing) on the fate of volatile fuel nitrogen, in four parts: (1) method

W. R. Seeker; M. P. Heap

1988-01-01

139

Experimental investigation of the atmospheric chemistry of aromatic hydrocarbons and long-chain alkanes. Final report  

Microsoft Academic Search

The interaction of volatile organic compounds (VOCs) and oxides of nitrogen in the presence of sunlight leads to the formation of ozone and other manifestations of photochemical air pollution. There are, however, significant uncertainties in our knowledge of the products and mechanisms of the atmospheric reactions of alkanes and aromatic hydrocarbons, important constituents of ambient air in urban areas, with

R. Atkinson; J. Arey; E. C. Tuazon; S. M. Aschmann; I. Bridier

1994-01-01

140

Reactions of o-benzyne with propargyl and benzyl radicals: potential sources of polycyclic aromatic hydrocarbons in combustion.  

PubMed

The kinetics and mechanisms of the reactions of o-benzyne with propargyl and benzyl radicals have been investigated computationally. The possible reaction pathways have been explored by quantum chemical calculations at the M06-2X/6-311+G(3df,2p)//B3LYP/6-311G(d,p) level and the mechanisms have been investigated by the Rice-Ramsperger-Kassel-Marcus theory/master-equation calculations. It was found that the o-benzyne associates with the propargyl and benzyl radicals without pronounced barriers and the activated adducts easily isomerize to five-membered ring species. Indenyl radical and fluorene + H were predicted to be dominantly produced by the reactions of o-benzyne with propargyl and benzyl radicals, respectively, with the rate constants close to the high-pressure limits at temperatures below 2000 K. The related reactions on the two potential energy surfaces, namely, the reaction between fulvenallenyl radical and acetylene and the decomposition reactions of indenyl and ?-phenylbenzyl radicals were also investigated. The high reactivity of o-benzyne toward the resonance stabilized radicals suggested a potential role of o-benzyne as a precursor of polycyclic aromatic hydrocarbons in combustion. PMID:22678346

Matsugi, Akira; Miyoshi, Akira

2012-06-08

141

Hydrocarbon-fuel/combustion-chamber-liner materials compatibility. Final Report, 31 Oct. 1989 - 31 Mar. 1991  

SciTech Connect

The results of dynamic tests using methane and NASA-Z copper test specimen under conditions that simulate those expected in the cooling channels of a regeneratively cooled LOX/hydrocarbon booster engine operating at chamber pressures up to 3000 psi are presented. Methane with less than 0.5 ppm sulfur contamination has little or no effect on cooling channel performance. At higher sulfur concentrations, severe corrosion of the NASA-Z copper alloy occurs and the cuprous sulfide Cu{sub 2}S, thus formed impedes mass flow rate and heat transfer efficiency. Therefore, it is recommended that the methane specification for this end use set the allowable sulfur content at 0.5 ppm (max). Bulk high purity liquid methane that meets this low sulfur requirement is currently available from only one producer. Pricing, availability, and quality assurance are discussed in detail. Additionally, it was found that dilute sodium cyanide solutions effectively refurbish sulfur corroded cooling channels in only 2 to 5 minutes by completely dissolving all the Cu{sub 2}S. Sulfur corroded/sodium cyanide refurbished channels are highly roughened and the increased surface roughness leads to significant improvements in heat transfer efficiency with an attendant loss in mass flow rate. Both the sulfur corrosion and refurbishment effects are discussed in detail.

Homer, G.D.

1991-04-01

142

Linking molecular level chemistry to macroscopic combustion behavior for nano-energetic materials with halogen containing oxides  

NASA Astrophysics Data System (ADS)

Coupling molecular scale reaction kinetics with macroscopic combustion behavior is critical to understanding the influences of intermediate chemistry on energy propagation, yet bridging this multi-scale gap is challenging. This study integrates ab initio quantum chemical calculations and condensed phase density functional theory to elucidate factors contributing to experimentally measured high flame speeds (i.e., >900 m/s) associated with halogen based energetic composites, such as aluminum (Al) and iodine pentoxide (I2O5). Experiments show a direct correlation between apparent activation energy and flame speed suggesting that flame speed is directly influenced by chemical kinetics. Toward this end, the first principle simulations resolve key exothermic surface and intermediate chemistries contributing toward the kinetics that promote high flame speeds. Linking molecular level exothermicity to macroscopic experimental investigations provides insight into the unique role of the alumina oxide shell passivating aluminum particles. In the case of Al reacting with I2O5, the alumina shell promotes exothermic surface chemistries that reduce activation energy and increase flame speed. This finding is in contrast to Al reaction with metal oxides that show the alumina shell does not participate exothermically in the reaction.

Farley, Cory W.; Pantoya, Michelle L.; Losada, Martin; Chaudhuri, Santanu

2013-08-01

143

Linking molecular level chemistry to macroscopic combustion behavior for nano-energetic materials with halogen containing oxides.  

PubMed

Coupling molecular scale reaction kinetics with macroscopic combustion behavior is critical to understanding the influences of intermediate chemistry on energy propagation, yet bridging this multi-scale gap is challenging. This study integrates ab initio quantum chemical calculations and condensed phase density functional theory to elucidate factors contributing to experimentally measured high flame speeds (i.e., >900 m?s) associated with halogen based energetic composites, such as aluminum (Al) and iodine pentoxide (I2O5). Experiments show a direct correlation between apparent activation energy and flame speed suggesting that flame speed is directly influenced by chemical kinetics. Toward this end, the first principle simulations resolve key exothermic surface and intermediate chemistries contributing toward the kinetics that promote high flame speeds. Linking molecular level exothermicity to macroscopic experimental investigations provides insight into the unique role of the alumina oxide shell passivating aluminum particles. In the case of Al reacting with I2O5, the alumina shell promotes exothermic surface chemistries that reduce activation energy and increase flame speed. This finding is in contrast to Al reaction with metal oxides that show the alumina shell does not participate exothermically in the reaction. PMID:23968101

Farley, Cory W; Pantoya, Michelle L; Losada, Martin; Chaudhuri, Santanu

2013-08-21

144

An investigation on polycyclic aromatic hydrocarbon emissions from pulverized coal combustion systems  

PubMed

Results from a series of tests conducted to study the emission of polynuclear or polycyclic aromatic hydrocarbons (PAHs) from bench-scale and small industrial, water-tube boiler are discussed. A Middle Kittanning, and Upper Freeport seam coals were used in the study. Samples were extracted from the reactor outlet and from the inlet and outlet sides of the research boiler's (RB) baghouse using EPA promulgated methods.Only acenaphthene and fluoranthene were detected in down-fired combustor (DFC) samples. In addition to these two, naphthalene was detected in the RB samples. Emission factors ranged from 80 to 320 &mgr;g/kg of fuel fired. Although there were minor trends in the emissions' data, given the reproducibility limits for PAH compounds, no significant differences were found in the emissions with respect to the fuel type or form (pulverized coal (PC) vs. coal-water slurry fuel (CWSF), and raw vs. cleaned coal) and firing conditions (high and low excess air). The PAH emissions showed a decrease with increase in the firing rate.A bench-scale drop-tube reactor (DTR) was used to study the effects of temperature and residence time on PAH formation. The results revealed near constant PAH concentrations in the solid-phase samples, while the PAH concentrations in the vapor-phase samples increased as a function of temperature. At a temperature of around 1300 degrees C, the rate of PAH formation was exceeded by the rate of PAH oxidation, and PAH concentrations in the vapor phase began to decrease. PMID:10781720

Pisupati; Wasco; Scaroni

2000-05-29

145

Chemistry  

NSDL National Science Digital Library

Finds ChemEd DL resources related to the sections of the General Chemistry textbook, Chemistry, by Kenneth W. Whitten, Raymond E. Davis, M. Larry Peck, George G. Stanley published by Brooks/Cole, 2010.

146

Low-temperature combustion chemistry of biofuels: pathways in the initial low-temperature (550 K-750 K) oxidation chemistry of isopentanol.  

PubMed

The branched C(5) alcohol isopentanol (3-methylbutan-1-ol) has shown promise as a potential biofuel both because of new advanced biochemical routes for its production and because of its combustion characteristics, in particular as a fuel for homogeneous-charge compression ignition (HCCI) or related strategies. In the present work, the fundamental autoignition chemistry of isopentanol is investigated by using the technique of pulsed-photolytic Cl-initiated oxidation and by analyzing the reacting mixture by time-resolved tunable synchrotron photoionization mass spectrometry in low-pressure (8 Torr) experiments in the 550-750 K temperature range. The mass-spectrometric experiments reveal a rich chemistry for the initial steps of isopentanol oxidation and give new insight into the low-temperature oxidation mechanism of medium-chain alcohols. Formation of isopentanal (3-methylbutanal) and unsaturated alcohols (including enols) associated with HO(2) production was observed. Cyclic ether channels are not observed, although such channels dominate OH formation in alkane oxidation. Rather, products are observed that correspond to formation of OH via?-C-C bond fission pathways of QOOH species derived from ?- and ?-hydroxyisopentylperoxy (RO(2)) radicals. In these pathways, internal hydrogen abstraction in the RO(2)? QOOH isomerization reaction takes place from either the -OH group or the C-H bond in ?-position to the -OH group. These pathways should be broadly characteristic for longer-chain alcohol oxidation. Isomer-resolved branching ratios are deduced, showing evolution of the main products from 550 to 750 K, which can be qualitatively explained by the dominance of RO(2) chemistry at lower temperature and hydroxyisopentyl decomposition at higher temperature. PMID:22286869

Welz, Oliver; Zádor, Judit; Savee, John D; Ng, Martin Y; Meloni, Giovanni; Fernandes, Ravi X; Sheps, Leonid; Simmons, Blake A; Lee, Taek Soon; Osborn, David L; Taatjes, Craig A

2012-01-30

147

Chemistry in plumes of high-flying aircraft with H 2 combustion engines: a modelling study  

NASA Astrophysics Data System (ADS)

. Recent discussions on high-speed civil transport (HSCT) systems have renewed the interest in the chemistry of supersonic-aircraft plumes. The engines of these aircraft emit large concentrations of radicals like O, H, OH, and NO. In order to study the effect of these species on the composition of the atmosphere, the detailed chemistry of an expanding and cooling plume is examined for different expansion models.

Weibring, G.; Zellner, R.

1994-05-01

148

Polycyclic aromatic hydrocarbons in smoke used to smoke cheese produced by the combustion of rock rose (Cistus monspeliensis) and tree heather (Erica arborea) wood.  

PubMed

In this work, the polycyclic aromatic hydrocarbons (PAHs) and their methyl derivatives concentrations have been determined in smoke from the rock rose and tree heather wood combustion. The combustion is done in two types of smokers, kiln and drum, commonly used in the Canary Islands (Spain) to smoke cheese. The low control of the operational conditions justify the great variability of the PAHs concentration in the emissions, with values between 251.8 and 2547 microg/m3N. In general, the lowest concentrations correspond to the tree heather wood combustion in the drum, while the highest concentrations are usually reached in the rock rose wood combustion in the kiln. However, the relative contributions of each PAH to the total concentration are independently similar to the type of smoker and wood used. In the combustion conditions, the equilibrium is not reached during the PAHs distribution process between the gas and aerosol phases. Therefore, while naphthalene and their 1- and 2-methyl derivatives remain in the gas phase, phenanthrene and PAHs with higher molecular weight remain mainly in the aerosol phase. In this phase, the PAHs concentration represents 39.9% of the total PAHs produced by burning rock rose wood and 29.1% of the total PAHs when tree heather wood is used. To establish the carcinogenic potential in both phases, the percentages of some PAHs were calculated. These values are significantly higher in the aerosol phase and, at the same time, higher when rock rose wood is used. PMID:15631526

Conde, Francisco J; Ayala, Juan H; Afonso, Ana M; González, Venerando

2005-01-12

149

Terascale High-Fidelity Simulations of Turbulent Combustion with Detailed Chemistry  

SciTech Connect

The TSTC project is a multi-university collaborative effort to develop a high-fidelity turbulent reacting flow simulation capability utilizing terascale, massively parallel computer technology. The main paradigm of our approach is direct numerical simulation (DNS) featuring highest temporal and spatial accuracy, allowing quantitative observations of the fine-scale physics found in turbulent reacting flows as well as providing a useful tool for development of sub-models needed in device-level simulations. The code named S3D, developed and shared with Chen and coworkers at Sandia National Laboratories, has been enhanced with new numerical algorithms and physical models to provide predictive capabilities for spray dynamics, combustion, and pollutant formation processes in turbulent combustion. Major accomplishments include improved characteristic boundary conditions, fundamental studies of auto-ignition in turbulent stratified reactant mixtures, flame-wall interaction, and turbulent flame extinction by water spray. The overarching scientific issue in our recent investigations is to characterize criticality phenomena (ignition/extinction) in turbulent combustion, thereby developing unified criteria to identify ignition and extinction conditions. The computational development under TSTC has enabled the recent large-scale 3D turbulent combustion simulations conducted at Sandia National Laboratories.

Hong G. Im; Arnaud Trouve; Christopher J. Rutland; Jacqueline H. Chen

2009-02-02

150

Exploratory Study to Determine the Ignition Properties and Combustion Chemistry of Explosives Using Shock Tube Methods.  

National Technical Information Service (NTIS)

We investigated the potential of a new experimental method for combustion studies of solid nano-particle energetic materials. This new method is based on the recent development in our laboratory of an aerosol shock tube and its combined use with laser ext...

D. F. Davidson R. K. Hanson

2008-01-01

151

Extended Lagrangian quantum molecular dynamics simulations of shock-induced chemistry in hydrocarbons  

SciTech Connect

A set of interatomic potentials for hydrocarbons that are based upon the self-consistent charge transfer tight-binding approximation to density functional theory have been developed and implemented into the quantum molecular dynamics code ''LATTE''. The interatomic potentials exhibit an outstanding level of transferability and have been applied in molecular dynamics simulations of tert-butylacetylene under thermodynamic conditions that correspond to its single-shock Hugoniot. We have achieved precise conservation of the total energy during microcanonical molecular dynamics trajectories under incomplete convergence via the extended Lagrangian Born-Oppenheimer molecular dynamics formalism. In good agreement with the results of a series of flyer-plate impact experiments, our SCC-TB molecular dynamics simulations show that tert-butylactylene molecules polymerize at shock pressures around 6.1 GPa.

Sanville, Edward J [Los Alamos National Laboratory; Bock, Nicolas [Los Alamos National Laboratory; Challacombe, William M [Los Alamos National Laboratory; Cawkwell, Marc J [Los Alamos National Laboratory; Niklasson, Anders M N [Los Alamos National Laboratory; Dattelbaum, Dana M [Los Alamos National Laboratory; Sheffield, Stephen [Los Alamos National Laboratory; Sewell, Thomas D [UNIV OF MISSOURI

2010-01-01

152

Experimental investigation of the atmospheric chemistry of aromatic hydrocarbons and long-chain alkanes. Final report  

SciTech Connect

The interaction of volatile organic compounds (VOCs) and oxides of nitrogen in the presence of sunlight leads to the formation of ozone and other manifestations of photochemical air pollution. There are, however, significant uncertainties in our knowledge of the products and mechanisms of the atmospheric reactions of alkanes and aromatic hydrocarbons, important constituents of ambient air in urban areas, with the hydroxyl (OH) radical. A series of product studies of the OH radical-initiated reactions of selected alkanes, ketones and alcohols have been carried out to obtain further insights into alkoxy radical isomerization. Product studies of the OH radical reaction with 4-methyl-2-pentanone, 2,6-dimethyl-4-heptanone, 2,4-dimethyl-2-pentanol and 3,5-dimethyl-3-hexanol in the presence of NOx have provided unambiguous evidence for alkoxy radical isomerization and these studies have provided rate constant ratios for the isomerization reaction versus alkoxy radical decomposition and reaction with O2.

Atkinson, R.; Arey, J.; Tuazon, E.C.; Aschmann, S.M.; Bridier, I.

1994-08-01

153

In silico bioremediation of polycyclic aromatic hydrocarbon: a frontier in environmental chemistry.  

PubMed

In recent years, the number of studies in the field of bioremediation has been growing steadily. Although a large number of studies provide information that is highly detailed and offer great amounts of knowledge on a given subject, the downside is that the hunt for more information requires the combined efforts of researchers from many areas, which are becoming increasingly difficult to attain. In this review, we present an overview of recent work investigating enzyme degradation of polycyclic aromatic hydrocarbons. In the first part, this review examines several of the new enzymes able to degrade pollutants, with special attention being given to those with a well-resolved structure. The second part explores some of the most recent work in which computational approaches, such as molecular dynamics, docking, density functional theory and database retrieval, have been employed to study enzymes with specific bioremediation activities. PMID:23732301

Librando, Vito; Pappalardo, Matteo

2013-05-14

154

A flame tabulated chemistry approach for premixed combustion using industrial CFD codes  

Microsoft Academic Search

A flame tabulated model to account for detailed chemistry is used along with a presumed PDF approach to simulate a lean turbulent premixed flame stabilized behind a conical bluff body. Here, the FPI model is retained to build the chemical database. The resulting look-up tables are then coupled with CEDRE, the ONERA code for aerothermochemistry problems. The coupling between CEDRE

J. Savre; N. Bertier; D. Gaffié

155

The role of analytical chemistry in assessing atmospheric effects of combustion  

Microsoft Academic Search

This paper discusses sampling and analysis strategies designed to distinguish local and regional sulfate and to identify heterogeneous SOâ oxidation in an urban heavily polluted atmosphere. The role of analytical chemistry will be illustrated by reviewing the results of a multi-year international cooperative study conducted principally in Ljubljana, Yugoslavia. The analytical results, when combined with physical measurements and meteorological data,

Novakov

1987-01-01

156

Terascale High-Fidelity Simulations of Turbulent Combustion with Detailed Chemistry  

SciTech Connect

This SciDAC project enabled a multidisciplinary research consortium to develop a high fidelity direct numerical simulation (DNS) software package for the simulation of turbulent reactive flows. Within this collaboration, the authors, based at CMU's Pittsburgh Supercomputing Center (PSC), focused on extensive new developments in Sandia National Laboratories' "S3D" software to address more realistic combustion features and geometries while exploiting Terascale computational possibilities. This work significantly advances the state-of-the-art of DNS of turbulent reacting flows.

Raghurama Reddy; Roberto Gomez; Junwoo Lim; Yang Wang; Sergiu Sanielevici

2004-10-15

157

Effects of hydrocarbon addition on cellular instabilities in expanding syngas–air spherical premixed flames  

Microsoft Academic Search

Experiments were conducted in a constant pressure combustion chamber using high-speed schlieren imaging to investigate the effects of hydrocarbon addition on cellular instabilities of syngas–air flames at room temperature and elevated pressures. The measured laminar burning velocities were compared with the predicted results computed using some reliable kinetic mechanisms with detailed transport and chemistry. The cellular instabilities for the hydrocarbon-added

Tran Manh Vu; Jeong Park; Oh Boong Kwon; Jeong Soo Kim

2009-01-01

158

Climatology and Atmospheric Chemistry of Non-Methane Hydrocarbon Emissions over the North Atlantic  

NASA Astrophysics Data System (ADS)

Non-methane hydrocarbons (NMHC) spanning the C2-C7 volatility range have been monitored at the Pico Mountain Observatory, located at 2,225 m a.s.l., on Pico Island, in the Azores, Portugal, since 2004. Observations at this site, due to the topography, location, and height of the station, during most times reflect long-range transport of air from the continents bordering the North Atlantic. The multi-year data records show that NMHC mole fractions exhibit regular annual cycles with winter maxima and summer minima. Short-term variability of the data is driven by transport events typically lasting 2-5 days. During these events NMHC absolute levels show significant increases over their seasonal background. NMHC ratios were applied to estimate the degree of photochemical processing and transport time to the station. Transport events identified from the NMHC data were then analyzed for emission source region and transport pathway using HYSPLIT model outputs. The multi-year observations were applied to develop a seasonality of the pollution transport to Pico and contributing source regions. These analyses show that emissions from the North American continent are the primary cause for elevated NMHC levels observed at the station. Most identified transport events originate from urban areas; biomass burning transport from boreal North America was identified in a few selected cases during late summer. Emissions in air transported from Europe and Africa were encountered only on a few occasions.

Helmig, Detlev; Hueber, Jacques; Munoz, Mauricio; Mazzoleni, Claudio; Mazzoleni, Lynn; Owen, Robert; Val-Martin, Maria; Fialho, Paulo

2013-04-01

159

Constraints on emissions of hydrocarbons and combustion tracers in the Colorado Front Range using observations of 14CO2 at the Boulder Atmospheric Observatory (BAO)  

NASA Astrophysics Data System (ADS)

Bottom-up inventories of trace gases formed as a byproduct of fossil fuel combustion have significant uncertainty associated with them because of the difficulty in quantifying the relationship between the mass of fuel consumed and the mass emitted; this is in contrast to the near stoichiometric production of CO2 from the combustion of hydrocarbons. Emissions of species such as CO, CH4, acetylene, and benzene depend greatly on a number of variables including fuel type, combustion temperature, oxidant-to-fuel ratio, and post-combustion tail-pipe or flue-stack "scrubbing". Given the impact of many of these combustion by-products on air quality, human health, and climate, atmospheric observations are necessary in order to critically evaluate bottom-up emissions estimates. Atmospheric radiocarbon (14C) represents an important observational constraint on emissions of fossil-fuel derived carbon into the atmosphere due to the near absence of 14C in fossil fuel reservoirs. The high sensitivity and precision that accelerator mass spectrometry (AMS) affords in atmospheric 14C analysis has greatly increased the potential for using such measurements to verify bottom-up emissions inventories of fossil fuel CO2 (CO2ff), as well as other co-emitted species. Here we use observations of 14CO2 and a series of hydrocarbons and combustion tracers from the Boulder Atmospheric Observatory (BAO; Lat: 40.050o, Lon: -105.004o) to derive emission ratios of each species to CO2. From these emission ratios, we estimate absolute emission fluxes of these species by using an existing CO2ff inventory. Among the species considered are CO, CH4, acetylene (C2H2), benzene (C6H6), and C3-C5 alkanes. Comparisons of top-down emissions estimates are made to existing inventories of these species for the region, where available, as well as to previous efforts to estimate emissions from atmospheric observations in the Colorado Front Range.We find that CO is overestimated in the NEI 2008 by a factor of ~2; a close evaluation of the inventory suggests that the CO emissions per unit fuel burned from on-road gasoline vehicles is likely significantly over-estimated. Emissions estimates of CH4 and the C3-C5 alkanes from gas and oil drilling and processing operations to the north and east of the BAO tower are in good agreement with previous top-down estimates for the region.

LaFranchi, B. W.; Petron, G.; Miller, J. B.; Lehman, S. J.; Andrews, A. E.; Dlugokencky, E. J.; Miller, B. R.; Montzka, S. A.; Turnbull, J. C.; Tans, P. P.; Guilderson, T. P.

2011-12-01

160

Oxidation chemistry of cyclic hydrocarbons in a motored engine: Methylcyclopentane, tetralin, and decalin  

SciTech Connect

This work, which parallels a recent study of cyclohexane and methylcyclohexane by the authors, concerns the oxidation chemistry of methylcyclopentane (MCP), 1,2,3,4-tetrahydronaphthalene (tetralin), and decahydronaphthalene (decalin) in a motored engine at low to intermediate temperatures. The experiment is conducted with variable compression ratio from 4 to 15 at equivalence ratio of 0.25 and fixed intake temperature. Results show dramatically different reactivity in low temperature oxidation for the three compounds. MCP and tetralin show little low temperature reaction prior to autoignition, while decalin shows significant low temperature reactivity. Detailed product analysis showed that conjugate olefins, the olefin having the identical structure with the reactant except the only C=C bond, account for over 70% of the products from MCP and an even higher percentage of the products from tetralin. Tetralin oxidation under the present conditions is essentially oxidative dehydrogenation with little oxygenated cyclic compound being formed. Hydronaphthalenes with various degrees of unsaturation are detected in the products from decalin, but are not as prevalent as in the case of MCP and tetralin, because of the high selectivity toward low temperature chain branching. The ring-opening paths in decalin oxidation are discussed, suggesting that breaking the common C-C bond of the two rings is more likely than opening the two rings one after the other. Methyl substitution on the ring was found to significantly promote the formation of propene relative to ethene. Reaction mechanisms are proposed to explain the major products formed from each compound. (author)

Yang, Yi; Boehman, Andre L. [EMS Energy Institute, The Pennsylvania State University, University Park, PA 16802 (United States)

2010-03-15

161

Numerical studies of the heterogeneous combustion of char using detailed chemistry.  

PubMed

The oxidation of graphite is used as a model system for the combustion of char. In order to understand this oxidation process a stagnation-point flow of an oxygen stream on a graphite surface is investigated numerically. The chemical reactions in the gas phase as well as on the surface are modelled by a series of elementary steps. The surface reactions take into consideration the different surface complexes formed, the influence of the geometry of the graphite surface and the interaction of gas-phase molecules with surface complexes. The rate coefficients used are estimated by applying methods of the microkinetic analysis of heterogeneous catalytic reactions. The mechanism is used to simulate the combustion rate of a graphite surface and the ratio of CO to CO2 formed on the surface. The simulation results are compared with experimental data and a good agreement is achieved. Furthermore, the fraction of char-bound nitrogen converted to N2 and N2O is calculated. PMID:11219686

Miessen, G; Behrendt, F; Deutschmann, O; Warnatz, J

162

Chemistry Notes.  

ERIC Educational Resources Information Center

|Presents background information, laboratory procedures, classroom materials/activities, and experiments for chemistry. Topics include superheavy elements, polarizing power and chemistry of alkali metals, particulate carbon from combustion, tips for the chemistry laboratory, interesting/colorful experiments, behavior of bismuth (III) iodine, and…

School Science Review, 1982

1982-01-01

163

Chemistry  

NSDL National Science Digital Library

Chemistry is the scientific study of matter and its interaction with other matter and with energy. It is the branch of natural science that deals with the composition of substances and their properties and reactions.

K-12 Outreach,

164

Distribution of hydrocarbons between oils and associated fine-grained sedimentary rocks: physical chemistry applied to petroleum geochemistry. II  

Microsoft Academic Search

Amounts and ratios of hydrocarbons in nonreservoir rocks (potential source rocks) can be compared with associated oils if, in relatively old and stable geologic situations, the hydrocarbons reach or closely approach a distribution equilibrium between source rock and reservoir. A distribution-equilibrium equation makes possible the calculation of the composition of a hypothetical oil expected from the composition of the hydrocarbons

A. Young; R. D. McIver

1977-01-01

165

Terascale High-Fidelity Simulations of Turbulent Combustion with Detailed Chemistry: Spray Simulations  

SciTech Connect

The Terascale High-Fidelity Simulations of Turbulent Combustion (TSTC) project is a multi-university collaborative effort to develop a high-fidelity turbulent reacting flow simulation capability utilizing terascale, massively parallel computer technology. The main paradigm of the approach is direct numerical simulation (DNS) featuring the highest temporal and spatial accuracy, allowing quantitative observations of the fine-scale physics found in turbulent reacting flows as well as providing a useful tool for development of sub-models needed in device-level simulations. Under this component of the TSTC program the simulation code named S3D, developed and shared with coworkers at Sandia National Laboratories, has been enhanced with new numerical algorithms and physical models to provide predictive capabilities for turbulent liquid fuel spray dynamics. Major accomplishments include improved fundamental understanding of mixing and auto-ignition in multi-phase turbulent reactant mixtures and turbulent fuel injection spray jets.

Rutland, Christopher J.

2009-04-26

166

Finite rate chemistry and presumed PDF models for premixed turbulent combustion  

SciTech Connect

The sensitivity of the prediction of mean reaction rates in turbulent premixed flames to presumed PDF shape is studied. Three different presumed PDF shapes are considered: (i) a beta function PDF, (ii) a twin delta function PDF, and (iii) a PDF based on unstrained laminar flame properties. The unstrained laminar flame has the same thermochemistry as the turbulent flame. Emphasis is placed on capturing the finite rate chemistry effects and obtaining a simple expression for the mean reaction rate. It is shown that, as the PDFs approach their bimodal limit, the mean reaction rate expressions obtained using the above three PDFs reduce to a common form. These expressions differ only in the numerical value of a multiplying factor. Predictions are compared with DNS data. Under the conditions of this comparison, the beta function and twin delta function PDFs lead to significant errors, while the PDF based on properties of an unstrained laminar flame gives good agreement with the DNS. (author)

Bray, K.N.C.; Swaminathan, N. [Cambridge University, Cambridge (United Kingdom); Champion, M. [Laboratoire de Combustion et de Detonique, UPR9028 CNRS, ENSMA, 86961 Futuroscope (France); Libby, P.A. [University of California, San Diego, La Jolla, CA (United States)

2006-09-15

167

THERMOCHEMISTRY OF HYDROCARBON RADICALS  

SciTech Connect

Gas phase negative ion chemistry methods are employed to determine enthalpies of formation of hydrocarbon radicals that are important in combustion processes and to investigate the dynamics of ion-molecule reactions. Using guided ion beam tandem mass spectrometry, we measure collisional threshold energies of endoergic proton transfer and hydrogen atom transfer reactions of hydrocarbon molecules with negative reagent ions. The measured reaction threshold energies for proton transfer yield the relative gas phase acidities. In an alternative methodology, competitive collision-induced dissociation of proton-bound ion-molecule complexes provides accurate gas phase acidities relative to a reference acid. Combined with the electron affinity of the R {center_dot} radical, the gas phase acidity yields the RH bond dissociation energy of the corresponding neutral molecule, or equivalently the enthalpy of formation of the R{center_dot} organic radical, using equation: D(R-H) = {Delta}{sub acid}H(RH) + EA(R) - IE(H). The threshold energy for hydrogen abstraction from a hydrocarbon molecule yields its hydrogen atom affinity relative to the reagent anion, providing the RH bond dissociation energy directly. Electronic structure calculations are used to evaluate the possibility of potential energy barriers or dynamical constrictions along the reaction path, and as input for RRKM and phase space theory calculations. In newer experiments, we have measured the product velocity distributions to obtain additional information on the energetics and dynamics of the reactions.

Kent M. Ervin, Principal Investigator

2004-08-17

168

The importance of thermodynamics to the modeling of nitrogen combustion chemistry  

SciTech Connect

Modeling calculations have been performed to illustrate the effect of using five commonly accepted data bases of thermochemical properties on predictions of temporal species profiles. The thermochemical properties are those used for the determination of equilibrium constants employed in the calculation of reverse rate coefficients for a chemical mechanism where forward rate coefficients are specified. The modeling study was performed for hydrogen/oxygen/argon/nitrogen-compound mixtures where the nitrogen compound was either NO or NH/sub 3/. The mixtures reacted isothermally at 1600 K and isobarically at 1 atmosphere, and a single kinetic mechanism for which forward rate coefficients were specified was used throughout. Mixtures of equivalence ratios of 0. 625, 1.0 and 1.6 were considered. Modifications in sources of thermodynamic data have been substantial since 1971 for some species. Among the data bases, thermochemical properties varied greatly for the species NH, NH/sub 2/, NNH, and HO/sub 2/, and those for other species important in the mechanism had variations of less than 10 percent. The thermochemical property variations among the data bases in NH, NH/sub 2/ and NNH have substantial effects upon the temporal species profiles for nitrogenous species. While this result is not surprising, unfortunately, it is often overlooked when modeling results are compared. This effect is most pronounced for rich combustion, and varies directly with equivalence ratio. Use of different data bases had little effect on the H/O species profiles. Radical species profiles (with the exception of HO/sub 2/) tend to be influenced strongly by their own thermochemical properties. Computed profiles also were shown to be independent of algorithm (HCT or CHEMKIN) and thermodynamic property fitting procedure between 1000 and 2000/degree/K. 24 refs., 3 tabs.

Martin, R.J.; Brown, N.J.

1988-07-01

169

On the effects of hydrocarbon and sulphur-containing compounds on the CCN activation of combustion particles  

NASA Astrophysics Data System (ADS)

The European PartEmis project (''Measurement and prediction of emissions of aerosols and gaseous precursors from gas turbine engines'') was focussed on the characterisation and quantification of exhaust emissions from a gas turbine engine. A comprehensive suite of aerosol, gas and chemi-ion measurements were conducted under different combustor operating conditions and fuel sulphur concentrations. Combustion aerosol characterisation included on-line measurements of mass and number concentration, size distribution, mixing state, thermal stability of internally mixed particles, hygroscopicity, cloud condensation nuclei (CCN) activation potential, and off-line analysis of chemical composition. Modelling of CCN activation of combustion particles was conducted using microphysical and chemical properties obtained from the measurements as input data. Based on this unique data set, the role of sulphuric acid coatings on the combustion particles, formed in the cooling exhaust plume through either direct condensation of gaseous sulphuric acid or coagulation with volatile condensation particles nucleating from gaseous sulphuric acid, and the role of the organic fraction for the CCN activation of combustion particles was investigated. It was found that particles containing a large fraction of non-volatile organic compounds grow significantly less at high relative humidity than particles with a lower content of non-volatile OC. Also the effect of the non-volatile OC fraction on the potential CCN activation is significant. While a coating of water-soluble sulphuric acid increases the potential CCN activation, or lowers the activation diameter, respectively, the non-volatile organic compounds, mainly found at lower combustion temperatures, can partially compensate this sulphuric acid-related enhancement of CCN activation of carbonaceous combustion aerosol particles.

Petzold, A.; Gysel, M.; Vancassel, X.; Hitzenberger, R.; Puxbaum, H.; Vrochticky, S.; Weingartner, E.; Baltensperger, U.; Mirabel, P.

2005-05-01

170

Interactive chemistry in the Laboratoire de Météorologie Dynamique general circulation model: model description and impact analysis of biogenic hydrocarbons on tropospheric chemistry  

NASA Astrophysics Data System (ADS)

We present a description and evaluation of LMDz-INCA, a global three-dimensional chemistry-climate model, pertaining to its recently developed NMHC version. In this substantially extended version of the model a comprehensive representation of the photochemistry of non-methane hydrocarbons (NMHC) and volatile organic compounds (VOC) from biogenic, anthropogenic, and biomass-burning sources has been included. The tropospheric annual mean methane (9.2 years) and methylchloroform (5.5 years) chemical lifetimes are well within the range of previous modelling studies and are in excellent agreement with estimates established by means of global observations. The model provides a reasonable simulation of the horizontal and vertical distribution and seasonal cycle of CO and key non-methane VOC, such as acetone, methanol, and formaldehyde as compared to observational data from several ground stations and aircraft campaigns. LMDz-INCA in the NMHC version reproduces tropospheric ozone concentrations fairly well throughout most of the troposphere. The model is applied in several sensitivity studies of the biosphere-atmosphere photochemical feedback. The impact of surface emissions of isoprene, acetone, and methanol is studied. These experiments show a substantial impact of isoprene on tropospheric ozone and carbon monoxide concentrations revealing an increase in surface O3 and CO levels of up to 30 ppbv and 60 ppbv, respectively. Isoprene also appears to significantly impact the global OH distribution resulting in a decrease of the global mean tropospheric OH concentration by approximately 0.7×105 molecules cm-3 or roughly 8% and an increase in the global mean tropospheric methane lifetime by approximately seven months. A global mean ozone net radiative forcing due to the isoprene induced increase in the tropospheric ozone burden of 0.09 W m-2 is found. The key role of isoprene photooxidation in the global tropospheric redistribution of NOx is demonstrated. LMDz-INCA calculates an increase of PAN surface mixing ratios ranging from 75 to 750 pptv and 10 to 250 pptv during northern hemispheric summer and winter, respectively. Acetone and methanol are found to play a significant role in the upper troposphere/lower stratosphere (UT/LS) budget of peroxy radicals. Calculations with LMDz-INCA show an increase in HOx concentrations region of 8 to 15% and 10 to 15% due to methanol and acetone biogenic surface emissions, respectively. The model has been used to estimate the global tropospheric CO budget. A global CO source of 3019 Tg CO yr-1 is estimated. This source divides into a primary source of 1533 Tg CO yr-1 and secondary source of 1489 Tg CO yr-1 deriving from VOC photooxidation. Global VOC-to-CO conversion efficiencies of 90% for methane and between 20 and 45% for individual VOC are calculated by LMDz-INCA.

Folberth, G. A.; Hauglustaine, D. A.; Lathière, J.; Brocheton, F.

2006-06-01

171

Characterizing priority polycyclic aromatic hydrocarbons (PAH) in particulate matter from diesel and palm oil-based biodiesel B15 combustion  

Microsoft Academic Search

A set of 16 priority polycyclic aromatic hydrocarbons (PAH) associated with particulate matter (PM), emitted by a diesel engine fueled with petroleum diesel and a 15%-vol. palm oil methyl ester blend with diesel (B15), were determined. PM was filtered from a sample of the exhaust gas with the engine running at a steady speed and under no load. PAH were

Nestor Y. Rojas; Harvey Andrés Milquez; Hugo Sarmiento

2011-01-01

172

Effect of Hydrocarbon Emissions from PCCI-Type Combustion on the Performance of Selective Catalytic Reduction Catalysts.  

National Technical Information Service (NTIS)

Core samples cut from full size commercial Fe-and Cu-zeolite SCR catalysts were exposed to a slipstream of raw engine exhaust from a 1.9-liter 4-cylinder diesel engine operating in conventional and PCCI combustion modes. Subsequently, the NOx reduction pe...

J. A. Pihl J. E. Parks S. A. Lewis V. Y. Prikhodko

2011-01-01

173

Spatial distribution of polycyclic aromatic hydrocarbons in soil, sediment, and combusted residue at an e-waste processing site in southeast China.  

PubMed

The environmental pollution and health impacts caused by the primitive and crude recycling of e-waste have become urgent global issues. Guiyu, China is a major hotspot of e-waste recycling. In this study, the levels and distribution of polycyclic aromatic hydrocarbons in soil in Guiyu were determined to investigate the effect of e-waste activities on the environment and to identify possible sources of these pollutants. Sediment samples from a local duck pond, water gullies, a river tributary, and combusted residue from e-waste burning sites were also investigated. The general trend found in soil (?16 PAHs) was acid leaching site?>?duck pond?>?rice field?>?printer roller dump site?>?reservoir (control site) and ranged from 95.2?±?54.2 to 5,210?±?89.6 ng/g (dry wt). The highest average total PAH concentrations were found in combusted residues of wires, cables, and other computer electrical components located at two e-waste open burning sites (18,600 and 10,800?±?3,940 ng/g). These were 195- and 113-fold higher than the PAH concentrations of soil at the control site. Sediment PAH concentrations ranged from 37.2?±?6 to 534?±?271 ng/g. Results of this study provide further evidence of significant input of PAHs to the environment attributed to crude e-waste recycling. PMID:23338991

Leung, Anna O W; Cheung, Kwai Chung; Wong, Ming Hung

2013-01-22

174

Polynuclear aromatic hydrocarbon and particulate emissions from two-stage combustion of polystyrene: the effects of the secondary furnace (afterburner) temperature and soot filtration.  

PubMed

Laboratory experiments were conducted in a two-stage horizontal muffle furnace in order to monitor emissions from batch combustion of polystyrene (PS) and identify conditions that minimize them. PS is a dominant component of municipal and hospital waste streams. Bench-scale combustion of small samples (0.5 g) of shredded styrofoam cups was conducted in air, using an electrically heated horizontal muffle furnace, kept at Tgas = 1000 degrees C. Upon devolatilization, combustion of the polymer took place in a diffusion flame over the sample. The gaseous combustion products were mixed with additional air in a venturi and were channeled to a secondary muffle furnace (afterburner) kept at Tgas = 900-1100 degrees C; residence time therein varied between 0.6 and 0.8 s. At the exits of the primary and the secondary furnace the emissions of CO, CO2, O2, NOx, particulates as well as volatile and semivolatile hydrocarbons, such as polycyclic aromatic hydrocarbons (PAH), were monitored. Online analyzers, gravimetric techniques, and gas chromatography coupled to mass spectrometry (GC-MS) were used. Experiments were also conducted with a high-temperature barrier filter, placed just before the exit of the primary furnace to prevent the particulates from entering into the secondary furnace. Results demonstrated the beneficial effect of the afterburner in reducing PAH concentrations, including those of mutagenic species such as benzo[a]pyrene. Concentrations of individual PAH exhibited a pronounced after burner temperature dependence, typically ranging from a small decrease at 900 degrees C to a larger degree of consumption at 1100 degrees C. Consumption of PAH was observed to be the dominant feature at 900 degrees C, while significant quantities of benzene and some of its derivatives, captured by means of carbosieve/Carbotrap adsorbents, were formed in the afterburner at a temperature of 1000 degrees C. In the primary furnace, about 30% of the mass of the initial polystyrene was converted into soot, while the total mass of PAH represented about 3% of the initial mass of combustible. The afterburner reduced the particulate (soot) emissions by only 20-30%, which indicates that once soot is formed its destruction is rather difficult because its oxidation kinetics are slow undertypical furnace conditions. Moreover, increasing the afterburnertemperature resulted in an increasing trend of soot emissions therefrom, which might indicate competition between soot oxidation and formation, with some additional formation occurring at the higher temperatures. Contrary to the limited effect of the afterburner, high-temperature filtration of the combustion effluent prior to the exit of the primary furnace allowed for effective soot oxidation inside of the ceramic filter. Filtration drastically reduced soot emissions, by more than 90%. Limited soot formation in the afterburner was again observed with increasing temperatures. The yields of both CO and CO2 were largely unaffected by the temperature of the afterburner but increased at the presence of the filter indicating oxidation therein. A previously developed kinetic model was used to identify major chemical reaction pathways involving PAH in the afterburner. The experimental data at the exit of the primary furnace was used as input to these model computations. A first evaluation of the predictive capability of the model was conducted for the case with ceramic filter and a temperature of 900 degrees C. The afterburner was approximated as a plug-flow reactor, and model predictions at a residence time of 0.8 s were compared to experimental data collected at its exit. In agreement with the experimental PAH concentration, only a minor impact of the afterburner treatment was observed for most species at 900 degrees C. OH was deduced to be the major reactant with a mole fraction about 4 orders of magnitudes higher than that of hydrogen radicals. Evidence for the need of further work on the quantitative assessment of oxidation of PAH and their radicals is given. PMID:11878400

Wang, Jun; Richter, Henning; Howard, Jack B; Levendis, Yiannis A; Carlson, Joel

2002-02-15

175

Tropospheric chemistry of natural hydrocarbons, aldehydes, and peroxy radicals: Their connections to sulfuric acid production and climate effects.  

National Technical Information Service (NTIS)

Recent work has shown that natural hydrocarbon emissions can significantly affect the levels of urban and regional tropospheric ozone. We report on the reactivities of these biogenic trace gases, particularly isoprene, focusing on their importance in the ...

J. S. Gaffney N. A. Marley

1993-01-01

176

Facile preparation of hydrocarbon fuel-soluble nano-catalyst and its novel application in catalytic combustion of JP-10  

Microsoft Academic Search

Hexanethiol monolayer protected palladium clusters (Pd MPCs), which can be well dispersed in hydrocarbon fuels at nanometer scale (<1.5nm) were synthesized and characterized by TGA, DTA, NMR, FTIR, TEM and microcoulomb sulfur analysis. The particle size and thermal stability of Pd MPCs were sensitive to the thiol\\/Pd mole ratio in the initial reaction mixture. Moreover, Pd MPC was introduced to

Jianwei Wang; Yang Liu; Xiangwen Zhang; Zhentao Mi; Li Wang

2009-01-01

177

Emission characterization of particulate\\/gaseous phases and size association for polycyclic aromatic hydrocarbons from residential coal combustion  

Microsoft Academic Search

The emission characterization of polycyclic aromatic hydrocarbons (PAHs) emitted from the commonly used residential coal-stove in China was studied, including the partition between the particulate and gaseous phases and the distribution as a function of particle size. Smoke samples were taken by a PUF sampler and a size-segregated sampler through a dilution equipment and analyzed for PAHs using GC\\/MS. The

Yingjun Chen; Xinhui Bi; Bixian Mai; Guoying Sheng; Jiamo Fu

2004-01-01

178

Speciated Hydrocarbon and Carbon Monoxide Emissions from an Internal Combustion Engine Operating on Methyl Tertiary Butyl Ether-Containing Fuels  

Microsoft Academic Search

In the present work, engine and tailpipe (after a three-way catalytic converter) emissions from an internal combustion engine operating on two oxygenated blend fuels [containing 2 and 11% weight\\/weight (w\\/w) methyl tertiary butyl ether (MTBE)] and on a nonoxygenated base fuel were characterized. The engine (OPEL 1.6 L) was operated under various conditions, in the range of 0-20 HP. Total

S. G. Poulopoulos; C. J. Philippopoulos

2001-01-01

179

Forensic Chemistry  

NASA Astrophysics Data System (ADS)

Forensic chemistry is unique among chemical sciences in that its research, practice, and presentation must meet the needs of both the scientific and the legal communities. As such, forensic chemistry research is applied and derivative by nature and design, and it emphasizes metrology (the science of measurement) and validation. Forensic chemistry has moved away from its analytical roots and is incorporating a broader spectrum of chemical sciences. Existing forensic practices are being revisited as the purview of forensic chemistry extends outward from drug analysis and toxicology into such diverse areas as combustion chemistry, materials science, and pattern evidence.

Bell, Suzanne

2009-07-01

180

Reductions in emissions of carbonaceous particulate matter and polycyclic aromatic hydrocarbons from combustion of biomass pellets in comparison with raw fuel burning.  

PubMed

Biomass pellets are emerging as a cleaner alternative to traditional biomass fuels. The potential benefits of using biomass pellets include improving energy utilization efficiency and reducing emissions of air pollutants. To assess the environmental, climate, and health significance of replacing traditional fuels with biomass pellets, it is critical to measure the emission factors (EFs) of various pollutants from pellet burning. However, only a few field measurements have been conducted on the emissions of carbon monoxide (CO), particulate matter (PM), and polycyclic aromatic hydrocarbons (PAHs) from the combustion of pellets. In this study, pine wood and corn straw pellets were burned in a pellet burner (2.6 kW), and the EFs of CO, organic carbon, elemental carbon, PM, and PAHs (EF(CO), EF(OC), EF(EC), EF(PM), and EF(PAH)) were determined. The average EF(CO), EF(OC), EF(EC), and EF(PM) were 1520 ± 1170, 8.68 ± 11.4, 11.2 ± 8.7, and 188 ± 87 mg/MJ for corn straw pellets and 266 ± 137, 5.74 ± 7.17, 2.02 ± 1.57, and 71.0 ± 54.0 mg/MJ for pine wood pellets, respectively. Total carbonaceous carbon constituted 8 to 14% of the PM mass emitted. The measured values of EF(PAH) for the two pellets were 1.02 ± 0.64 and 0.506 ± 0.360 mg/MJ, respectively. The secondary side air supply in the pellet burner did not change the EFs of most pollutants significantly (p > 0.05). The only exceptions were EF(OC) and EF(PM) for pine wood pellets because of reduced combustion temperatures with the increased air supply. In comparison with EFs for the raw pine wood and corn straw, EF(CO), EF(OC), EF(EC), and EF(PM) for pellets were significantly lower than those for raw fuels (p < 0.05). However, the differences in EF(PAH) were not significant (p > 0.05). Based on the measured EFs and thermal efficiencies, it was estimated that 95, 98, 98, 88, and 71% reductions in the total emissions of CO, OC, EC, PM, and PAHs could be achieved by replacing the raw biomass fuels combusted in traditional cooking stoves with pellets burned in modern pellet burners. PMID:22568759

Shen, Guofeng; Tao, Shu; Wei, Siye; Zhang, Yanyan; Wang, Rong; Wang, Bin; Li, Wei; Shen, Huizhong; Huang, Ye; Chen, Yuanchen; Chen, Han; Yang, Yifeng; Wang, Wei; Wei, Wen; Wang, Xilong; Liu, Wenxing; Wang, Xuejun; Masse Simonich, Staci L y

2012-05-17

181

Reductions in Emissions of Carbonaceous Particulate Matter and Polycyclic Aromatic Hydrocarbons from Combustion of Biomass Pellets in Comparisonwith Raw Fuel Burning  

PubMed Central

Biomass pellets are emerging as a cleaner alternative to traditional biomass fuels. The potential benefits of using biomass pellets include improving energy utilization efficiency and reducing emissions of air pollutants. To assess the environmental, climate, and health significance of replacing traditional fuels with biomass pellets, it is critical to measure the emission factors (EFs) of various pollutants from pellet burning. However, only a few field measurements have been conducted on the emissions of carbon monoxide (CO), particulate matter (PM), and polycyclic aromatic hydrocarbons (PAHs) from the combustion of pellets. In this study, pine wood and corn straw pellets were burned in a pellet burner (2.6 kW) and the EFs of CO, organic carbon, elemental carbon, PM, and PAHs (EFCO, EFOC, EFEC, EFPM, and EFPAH) were determined. The average EFCO, EFOC, EFEC, and EFPM were 1520±1170, 8.68±11.4, 11.2±8.7, and 188±87 mg/MJ for corn straw pellets, and 266±137, 5.74±7.17, 2.02±1.57, and 71.0±54.0 mg/MJ for pine wood pellets, respectively. Total carbonaceous carbon constituted 8 to 14% of the PM mass emitted. The measured values of EFPAH for the two pellets were 1.02±0.64 and 0.506±0.360 mg/MJ, respectively. The secondary side air supply in the pellet burner did not change the EFs of most pollutants significantly (p > 0.05). The only exceptions were EFOC and EFPM for pine wood pellets because of reduced combustion temperatures with the increased air supply. In comparison with EFs for the raw pine wood and corn straw, EFCO, EFOC, EFEC, and EFPM for pellets were significantly lower than those for raw fuels (p < 0.05). However, the differences in EFPAH were not significant (p > 0.05). Based on the measured EFs and thermal efficiencies, it was estimated that 95, 98, 98, 88, and 71% reductions in the total emissions of CO, OC, EC, PM, and PAHs could be achieved by replacing the raw biomass fuels combusted in traditional cooking stoves with pellets burned in modern pellet burners.

SHEN, Guofeng; TAO, Shu; WEI, Siye; ZHANG, Yanyan; WANG, Rong; WANG, Bin; LI, Wei; SHEN, Huizhong; HUANG, Ye; CHEN, Yuanchen; CHEN, Han; YANG, Yifeng; WANG, Wei; WEI, Wen; WANG, Xilong; LIU, Wenxing; WANG, Xuejun; SIMONICH, Staci L. Massey

2012-01-01

182

Quantum-chemiModeling of Interstellar Grain Prebiotic Chemistry: Catalytic Synthesis of Glycine and Alanine on the Surface of a Polycyclic Aromatic Hydrocarbon Flake  

NASA Astrophysics Data System (ADS)

The formation pathways of amino acids, namely, glycine and alanine, on the surface of a polycyclic aromatic hydrocarbon flake (corone) are studied with a semiempirical, quantum-chemistry package referred to as CATIVIC. It is found that the stability of the carboxyl group (COOH) is enhanced by chemisorption that occurs in three adsorbate modes. In particular, the two-site mode enables us to make successive surface recombinations that result in chemisorbed amino-acid configurations that closely trace the surface geometry. This property imposes a strict handedness on amino acids assembled from side groups along the surface edge that, in the case of chiral surfaces, may lead to enantioselection as previously found by experiment. By comparing prospective reactions on a larger surface model (circumcoronene), evidence is found that favors amino-acid formation on the smaller flakes. Due to a lack of measurements, the main findings of the present work have been confirmed with an ab initio method.

Mendoza, C.; Ruette, F.; Martorell, G.; Rodríguez, L. S.

2004-01-01

183

Sandia Combustion Research: Technical review  

SciTech Connect

This report contains reports from research programs conducted at the Sandia Combustion Research Facility. Research is presented under the following topics: laser based diagnostics; combustion chemistry; reacting flow; combustion in engines and commercial burners; coal combustion; and industrial processing. Individual projects were processed separately for entry onto the DOE databases.

NONE

1995-07-01

184

Use of standards and reference materials in the measurement of chlorinated hydrocarbon residues: Chemistry workbook. Technical memo  

SciTech Connect

The document is a workbook on the use of standards and reference materials for a quality assurance/quality control (QA/QC) program for marine pollution studies of chlorinated hydrocarbons. The first sections of this workbook give details of sample collection, archival, extraction, instrumental analyses, and data reduction under proper QA/QC procedures. The last sections give examples of how the calculations and procedures are actually applied in a laboratory.

Wade, T.L.; Cantillo, A.Y.

1994-03-01

185

Sulphur stable isotope systematics in diagenetic pyrite from the North Sea hydrocarbon reservoirs revealed by laser combustion analysis.  

PubMed

Our study focuses on pyrite nodules developed in the Brent Group sandstones, which host the Brent Oilfield, one of the North Sea's greatest oil and gas producers. Timing of nodule formation is equivocal, but due to the forceful, penetrative textures that abound, it is considered late. This pyrite offers a research opportunity because it records the development of the supply of H(2)S in a hydrocarbon reservoir and its sulphur isotopic composition. Laser-based analysis of ?(34)S reveals an extraordinary diversity in values and patterns. The values range from-27 to+72‰, covering half the terrestrial range, with large variations at the submillimetre scale. Isotopically heavy (?(34)S ?+30‰ or higher) sulphide is endemic, but low ?(34)S pyrite is also present and appears to represent a temporally though not spatially (on the ?cm scale) distinct pyritisation event. The distribution of ?(34)S values within individual concretions can be normal (Gaussian), but in some cases may reflect progressive isotope fractionation process(es), conceivably of Rayleigh type. The source of the sulphur and the identity of the isotope fractionation process(es) remain enigmatic. PMID:22321244

Fallick, Anthony E; Boyce, Adrian J; McConville, Paul

2012-02-09

186

Introduction of Differential Scanning Calorimetry in a General Chemistry Laboratory Course: Determination of Thermal Properties of Organic Hydrocarbons  

ERIC Educational Resources Information Center

|In first-year general chemistry undergraduate courses, thermodynamics and thermal properties such as melting points and changes in enthalpy ([Delta]H) and entropy ([Delta]S) of phase changes are frequently discussed. Typically, classical calorimetric methods of analysis are used to determine [Delta]H of reactions. Differential scanning…

D'Amelia, Ronald; Franks, Thomas; Nirode, William F.

2007-01-01

187

Fundamental and semi-global kinetic mechanisms of hydrocarbon combustion. Final report, 1 July 1981-30 June 1983. [99 references  

SciTech Connect

This program developed and significantly expanded the available data base at intermediate temperatures (approx. Ca 1000 K) on the oxidation characteristics of higher carbon number paraffins including, n-butane, iso-butane, n-octane and 2,2,4 tri-methyl pentane (iso-octane). These data provide insight into the intermediates and products formed at atmospheric pressure during oxidation of these species over a range of equivalence ratios from fuel-lean to fuel-rich conditions. This reversible semi-empirical model and similar mechanisms with overall rate parameters developed from the experimental work described were evaluated by comparing predictions with the experimental data from this program as well as literature data available from shock tubes. By modifying only the fuel conversion rate to intermediate species, acceptable reproducibility of intermediate and final product evaluation at intermediate temperatures, and ignition delay phenomena at shock tube temperatures could be achieved, for n-butane, iso-butane, and n-octane. Intermediate product characteristics for iso-octane are different than that of the other fuels studied, and the model considered was not extendable to this fuel. The program also continued expansion of understanding for the oxidation of simple aromatic structures through additional flow reactor studies on benzene, toluene, and ethylbenzene. These data were used to formulate a general mechanism for the oxidation of simple ring compounds, and to point to the important phenomena which should be considered in developing an empirical description of the chemistry for combustion modelling.

Brezinsky, K.; Dryer, F.L.

1983-10-01

188

Chemistry Impacts in Gasoline HCCI  

SciTech Connect

The use of homogeneous charge compression ignition (HCCI) combustion in internal combustion engines is of interest because it has the potential to produce low oxides of nitrogen (NOx) and particulate matter (PM) emissions while providing diesel-like efficiency. In HCCI combustion, a premixed charge of fuel and air auto-ignites at multiple points in the cylinder near top dead center (TDC), resulting in rapid combustion with very little flame propagation. In order to prevent excessive knocking during HCCI combustion, it must take place in a dilute environment, resulting from either operating fuel lean or providing high levels of either internal or external exhaust gas recirculation (EGR). Operating the engine in a dilute environment can substantially reduce the pumping losses, thus providing the main efficiency advantage compared to spark-ignition (SI) engines. Low NOx and PM emissions have been reported by virtually all researchers for operation under HCCI conditions. The precise emissions can vary depending on how well mixed the intake charge is, the fuel used, and the phasing of the HCCI combustion event; but it is common for there to be no measurable PM emissions and NOx emissions <10 ppm. Much of the early HCCI work was done on 2-stroke engines, and in these studies the CO and hydrocarbon emissions were reported to decrease [1]. However, in modern 4-stroke engines, the CO and hydrocarbon emissions from HCCI usually represent a marked increase compared with conventional SI combustion. This literature review does not report on HCCI emissions because the trends mentioned above are well established in the literature. The main focus of this literature review is the auto-ignition performance of gasoline-type fuels. It follows that this discussion relies heavily on the extensive information available about gasoline auto-ignition from studying knock in SI engines. Section 2 discusses hydrocarbon auto-ignition, the octane number scale, the chemistry behind it, its shortcomings, and its relevance to HCCI. Section 3 discusses the effects of fuel volatility on fuel and air mixing and the consequences it has on HCCI. The effects of alcohol fuels on HCCI performance, and specifically the effects that they have on the operable speed/load range, are reviewed in Section 4. Finally, conclusions are drawn in Section 5.

Szybist, James P [ORNL; Bunting, Bruce G [ORNL

2006-09-01

189

The stable carbon isotope fractionation for reactions of selected hydrocarbons with OH-radicals and its relevance for atmospheric chemistry  

NASA Astrophysics Data System (ADS)

Measurements of the kinetic isotope effect (KIE) for the reactions of light n-alkanes as well as for several unsaturated hydrocarbons, including alkenes, dienes, benzene, and ethyne with OH-radicals are presented. All measured KIEs are positive; that is, molecules containing only C-12 react faster than the C-13 labeled molecules. However, the KIEs for n-alkanes are quite small; between one and four permil. They can be explained mainly by the mass dependence of the collision frequency between the n-alkanes and OH-radicals. KIEs for the reaction of alkenes with OH-radicals are considerably higher. They can be explained by a fractionation of 24.5+/-1.1% for the addition of an OH-radical to a double bond. Inverse dependence on number of carbon atoms and mass dependence of the collision frequencies explain our observations. For benzene the KIE is slightly higher; for ethyne it is somewhat lower than expected from this simple model. For the reaction of many light nonmethane hydrocarbons (NMHC), especially of unsaturated hydrocarbons, with OH-radicals the KIEs are sufficiently large to have significant impact on the isotopic composition of atmospheric NMHC. A small series of stable carbon isotope ratio measurements of atmospheric NMHC were made in the greater Toronto area. Traffic related NMHC emissions were also studied for their stable carbon isotope ratios. From these data it is possible to quantitatively determine the extent of photochemical processing due to OH-radical reactions that the individual NMHC has experienced. Thus such measurements allow quantitative evaluation of the extent of chemical processing the different NMHC have gone through. This also includes the possibility to differentiate between the impact of local sources and regional or large scale transport. It is shown that in combination with concentration measurements isotope ratio measurements are extremely valuable to study the complex interaction between chemical removal mechanisms, mixing, and dilution processes.

Rudolph, J.; Czuba, E.; Huang, L.

2000-12-01

190

Hydrocarbon fuel composition containing carbonate additive  

SciTech Connect

Hydrocarbon fuel heavier than gasoline, especially diesel fuel compositions is described. It contains carbonate additives, preferably non-aromatic, metals-free carbonates, to reduce particulate emissions therefrom when combusted in an internal combustion engine.

Kanne, D.D.; Iwamoto, R.Y.

1990-02-27

191

Hydrocarbon fuel composition containing carbonate additive  

SciTech Connect

This patent describes hydrocarbon fuels heavier than gasoline, especially diesel fuel compositions. It contains carbonate additives, preferably non-aromatic, metals-free carbonates, to reduce particulate emissions therefrom when combusted in an internal combustion engine.

Dillon, D.M.; Iwamoto, R.Y.

1990-01-02

192

Catalytically enhanced combustion process  

SciTech Connect

This patent describes a fuel having improved combustion efficiency. It comprises a petroleum based liquid hydrocarbon; and a combustion catalyst comprising from about 18 to about 21 weight percent naphthalene, from about 75 to about 80 weight percent toluene, and from about 2.8 to about 3.2 weight percent benzyl alcohol.

Rodriguez, C.

1992-05-26

193

The lipid chemistry of an interfacial sediment from the Peru Continental Shelf: Fatty acids, alcohols, aliphatic ketones and hydrocarbons  

NASA Astrophysics Data System (ADS)

A sample of the sediment-water column interface which lies on the continental shelf under the Peru upwelling regime, has been examined for fatty acids, fatty alcohols, ketones and hydrocarbons. Fatty acids were the most abundant compound class, ranging from C 12 -C 24 , with 16:0 as the major component (765.5 g/g dry sediment). The alcohols were dominated by 3,7,11,15-tetramethylhexadeca-2-en-ol (phytol), with even-chain n -alcohols in the range C 14 -C 20 . The ketones consisted of C 37 -C 39 di- and tri-unsaturated alken-2-ones and alken-3-ones. Both alkanes and alkenes were present in the hydrocarbon fraction; the alkanes ranging from C 13 -- C 20 and comprising both straight chain and isoprenoid compounds; the alkenes consisting of isomeric pairs of C 25 branched trienes and tetraenes. The data indicate that the organic content has been contributed very largely from marine sources (probably mainly from phytoplankton and bacteria), showing little terrigenous influence. The presence of labile compounds such as polyunsaturated fatty acids (with two to six double bonds), implies that the sediment has undergone very little diagenetic alteration, and the lipids are probably largely unchanged from the state in which they actually reached the sediment. They may therefore serve as a useful baseline in assessing diagenesis in older sediments, where diagenetic transformations are more advanced.

Smith, D. J.; Eglinton, G.; Morris, R. J.

1983-12-01

194

Combustor nozzle for a fuel-flexible combustion system  

SciTech Connect

A combustor nozzle is provided. The combustor nozzle includes a first fuel system configured to introduce a syngas fuel into a combustion chamber to enable lean premixed combustion within the combustion chamber and a second fuel system configured to introduce the syngas fuel, or a hydrocarbon fuel, or diluents, or combinations thereof into the combustion chamber to enable diffusion combustion within the combustion chamber.

Haynes, Joel Meier (Niskayuna, NY); Mosbacher, David Matthew (Cohoes, NY); Janssen, Jonathan Sebastian (Troy, NY); Iyer, Venkatraman Ananthakrishnan (Mason, OH)

2011-03-22

195

REDUCED KINETICS AND COUPLING FUNCTIONS FOR CALCULATING CO AND NO EMISSIONS IN GAS-TURBINE COMBUSTION  

Microsoft Academic Search

A reduced chemical-kinetic mechanism consisting of two global steps for fuel oxidation and an additional step for NO production is proposed as the minimal chemistry description for calculating CO and NO emissions in gas-turbine combustion. Carbon monoxide is seen to emerge as the main intermediate during the fuel-oxidation process, which takes place in two steps: fast partial hydrocarbon oxidation to

ALAIN LÉPINETTE; AMABLE LIÑÁN; BENIGNO LÁZARO; ANTONIO L. SÁNCHEZ

2005-01-01

196

Gas phase chemistry in catalytic combustion of methane\\/air mixtures over platinum at pressures of 1 to 16 bar  

Microsoft Academic Search

The gas-phase combustion of fuel-lean methane\\/air premixtures over platinum was investigated experimentally and numerically in a laminar channel-flow catalytic reactor at pressures 1 bar?p?16 bar. In situ, spatially resolved one-dimensional Raman and planar laser induced fluorescence (LIF) measurements over the catalyst boundary layer were used to assess the concentrations of major species and of the OH radical, respectively. Comparisons between measured and

Michael Reinke; John Mantzaras; Rolf Bombach; Sabine Schenker; Andreas Inauen

2005-01-01

197

Tropospheric chemistry of natural hydrocarbons, aldehydes, and peroxy radicals: Their connections to sulfuric acid production and climate effects  

NASA Astrophysics Data System (ADS)

Recent work has shown that natural hydrocarbon emissions can significantly affect the levels of urban and regional tropospheric ozone. We report on the reactivities of these biogenic trace gases, particularly, isoprene, focusing on their importance in the production of aldehydes and peroxy radicals, leading to increased levels of hydrogen over regional forests. Hydrogen peroxide can lead to the wet oxidation of sulfur dioxide to acidic sulfate in aerosols, fogs, and clouds. In turn, acidic sulfate can act as a light scattering aerosol and a source of cloud condensation nuclei (CCN), potentially leading to global cooling. Aerosol sulfate and other dissolved organic and inorganic compounds can also play important roles as a greenhouse species in the lower troposphere.

Gaffney, J. S.; Marley, N. A.

1993-05-01

198

Non methane hydrocarbons chemistry in the atmosphere of an equatorial forest: A case of indirect photochemical production of OH radicals  

NASA Astrophysics Data System (ADS)

An experiment was conducted in the Guyana forest in March 1985, during which C2 - C6 non methane hydrocarbons (NMHC) were measured in the air, together with CO2 and its associated 13C isotopic composition. Owing to the very high atmospheric stability, strong vertical concentration gradients were observed close to the soil surface. Simple assumptions allow showing that NMHC are mainly destroyed by OH radicals whose concentration seems to be surprisingly high, around 1×107 radicals cm-3. An indirect photochemical production of these radicals is proposed. On the other hand, the fluxes of the different NMHC emitted from the litter were found to be small, in the range of 10-7 to 10-6 g of carbon per hour and per m².

Bonsang, B.; Kanakidou, M.; Lambert, G.

1987-12-01

199

Kinetic double-layer model of aerosol surface chemistry and gas-particle interactions (K2SURF): degradation of polycyclic aromatic hydrocarbons exposed to O3, NO2, H2O, OH and NO3  

Microsoft Academic Search

We present a kinetic double-layer surface model (K2-SURF) that describes the degradation of polycyclic aromatic hydrocarbons (PAHs) on aerosol particles exposed to ozone, nitrogen dioxide, water vapor, hydroxyl and nitrate radicals. The model is based on multiple experimental studies of PAH degradation and on the PRA framework (Pöschl et al., 2007) for aerosol and cloud surface chemistry and gas-particle interactions.

M. Shiraiwa; R. M. Garland; U. Pöschl

2009-01-01

200

Kinetic double-layer model of aerosol surface chemistry and gas-particle interactions (K2SURF): Degradation of polycyclic aromatic hydrocarbons exposed to O3, NO2, H2O, OH and NO3  

Microsoft Academic Search

We present a kinetic double-layer surface model (K2-SURF) that describes the degradation of polycyclic aromatic hydrocarbons (PAHs) on aerosol particles exposed to ozone, nitrogen dioxide, water vapor, hydroxyl and nitrate radicals [1]. The model is based on multiple experimental studies of PAH degradation and on the Pöschl-Rudich-Ammann (PRA) framework [2] for aerosol and cloud surface chemistry and gas-particle interactions. For

Manabu Shiraiwa; Rebecca M. Garland; Ulrich Pöschl

2010-01-01

201

Homogeneous chemistry of NO/sub x/ production and removal from fossil fuel combustion gases. Final technical report  

SciTech Connect

The reduction of NO/sub x/ emissions from stationary combustion sources by non-catalytic homogeneous chemical addition is a promising technique. Demonstrations in laboratory experiments and on a number of field scale combustors have shown that the addition of ammonia to the exhaust flow significantly reduces the NO concentrations in a narrow temperature range. This report summarizes the work performed to understand the detailed chemical mechanism which makes this reduction occur. A model describing the NH/sub i//NO/sub x/ chemical system is developed, and rates of the key reactions identified are measured in a high temperature fast flow reactor. Product channels for certain important reactions are also identified. The experimental results are incorporated into the computer code, and the model predictions are compared with laboratory and field test results. Possible additives other than ammonia are evaluated and discussed.

Silver, J.A.; Gozewski, C.M.; Kolb, C.E.

1980-11-01

202

Fundamental studies of fuel chemistry as related to internal combustion engine phenomena. Final technical report, October 1987--December 1989  

SciTech Connect

Intent of this research effort was to provide insight (through homogeneous gas phase kinetic studies at different constant pressures) to the fuel chemistry issues important to autoignition in engines. Conditions of the proposed experiments were chosen to be similar to engine parameters under knocking conditions: 700--1100 K temperatures, 1--20 atm pressures, and stoichiometries around 1. A variable pressure flow reactor was designed in which a range of reaction pressures and lower reaction temperatures could be accessed. Crossed beam optical access, continuous on-line gas sampling (nondispersive infrared, oxygen paramagnetic, H thermo-conductive, Fourier transform infrared, off-line GC, GC/mass spectrometric, wet chemical), and temperature measurements at the sampling location are available; reacting systems with reaction times ranging from 50--100 ms to 15--20 s can be studied. Testing has begun. Experiments on isobutene/oxygen mixtures have been conducted in the old atmospheric pressure flow reactor at 1150 K and in an equivalence ratio range of pyrolysis with 100 ppM oxygen background to 0.42. The kinetic model indicates that the inhibitory effect of isobutene at high temps is due to depletion of the active radical pool and formation of unreactive stable species and methyl radicals; isobutene oxidation/pyrolysis is heavily influenced by the chemistry of methyl radicals. The reaction of hydroperoxy radical (HO{sub 2}) with methyl radical and its effect on isobutene oxidation will be studied in the new reactor.

Dryer, F.L.; Brezinsky, K.

1990-09-01

203

Combustion chemistry of the propanol isomers - investigated by electron ionization and VUV-photoionization molecular-beam mass spectrometry  

SciTech Connect

The combustion of 1-propanol and 2-propanol was studied in low-pressure, premixed flat flames using two independent molecular-beam mass spectrometry (MBMS) techniques. For each alcohol, a set of three flames with different stoichiometries was measured, providing an extensive data base with in total twelve conditions. Profiles of stable and intermediate species, including several radicals, were measured as a function of height above the burner. The major-species mole fraction profiles in the 1-propanol flames and the 2-propanol flames of corresponding stoichiometry are nearly identical, and only small quantitative variations in the intermediate species pool could be detected. Differences between flames of the isomeric fuels are most pronounced for oxygenated intermediates that can be formed directly from the fuel during the oxidation process. The analysis of the species pool in the set of flames was greatly facilitated by using two complementary MBMS techniques. One apparatus employs electron ionization (EI) and the other uses VUV light for single-photon ionization (VUV-PI). The photoionization technique offers a much higher energy resolution than electron ionization and as a consequence, near-threshold photoionization-efficiency measurements provide selective detection of individual isomers. The EI data are recorded with a higher mass resolution than the PI spectra, thus enabling separation of mass overlaps of species with similar ionization energies that may be difficult to distinguish in the photoionization data. The quantitative agreement between the EI- and PI-datasets is good. In addition, the information in the EI- and PI-datasets is complementary, aiding in the assessment of the quality of individual burner profiles. The species profiles are supplemented by flame temperature profiles. The considerable experimental efforts to unambiguously assign intermediate species and to provide reliable quantitative concentrations are thought to be valuable for improving the mechanisms for higher alcohol combustion. (author)

Kasper, T. [Bielefeld University, Universitaetsstr. 25, 33615 Bielefeld (Germany); Combustion Research Facility, Sandia National Laboratories, Livermore, CA 94551 (United States); Osswald, P.; Struckmeier, U.; Kohse-Hoeinghaus, K. [Bielefeld University, Universitaetsstr. 25, 33615 Bielefeld (Germany); Taatjes, C.A. [Combustion Research Facility, Sandia National Laboratories, Livermore, CA 94551 (United States); Wang, J.; Cool, T.A. [School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853 (United States); Law, M.E.; Morel, A.; Westmoreland, P.R. [Department of Chemical Engineering, University of Massachusetts, Amherst, MA 01003 (United States)

2009-06-15

204

Combustion Demonstration Using Updated Flame Tornado  

Microsoft Academic Search

The combustion reaction is a significant topic of discussion in general chemistry, organic chemistry, and laboratory safety components of most high school and undergraduate chemistry curricula. This demonstration uses the combustion of different forms of cellulose and an updated version of the \\

Edward G. Senkbeil

2000-01-01

205

Thermal efficiency analysis in a hydrogen premixed combustion engine  

Microsoft Academic Search

Hydrogen has higher flame velocity and shorter quenching distance than hydrocarbon fuels, and is supposed to have special characteristics in the combustion process of internal combustion engines. In this research, contributors to thermal efficiency in a hydrogen premixed spark ignition engine were analyzed and compared with methane combustion. Results showed hydrogen combustion had higher cooling loss to combustion chamber wall,

Toshio Shudo; Yasuo Nakajima; Takayuki Futakuchi

2000-01-01

206

A comparison of the autoignition chemistry of n-butane and isobutane in an internal combustion engine  

SciTech Connect

Butane is the simplest alkane fuel for which more than a single structural isomer is possible. In the present study, n-butane and isobutane are used in a test engine to examine the importance of molecular structure in determining knock tendency, and the experimental results are interpreted using a detailed chemical kinetic model. A sampling valve was used to extract reacting gases from the combustion chamber of the engine. Samples were withdrawn at different times during the engine cycle, providing concentration histories of a wide variety of reactant, olefin, carbonyl, and other intermediate and product species. The chemical kinetic model predicted the formation of all the intermediate species measured in the experiments. The agreement between the measured and predicted values is mixed and is discussed. Calculations show that RO{sub 2} isomerization reactions are more important contributors to chain branching in the oxidation of n-butane than in isobutane. Chain branching in isobutane oxidation is dependent on H-atom abstraction reactions involving HO{sub 2} and CH{sub 3}O{sub 2} radicals that occur at higher temperatures than RO{sub 2} isomerization reactions. Therefore, an isobutane mixture must be raised to a higher temperature than a n-butane mixture to achieve the same overall rate of reaction. 33 refs., 6 figs., 2 tabs.

Wilk, R.D.; Green, R.M.; Pitz, W.J.; Westbrook, C.K.; Addagarla, S.; Miller, D.L.; Cernansky, N.P.

1990-01-01

207

Surrogate Model Development for Fuels for Advanced Combustion Engines  

Microsoft Academic Search

The fuels used in internal-combustion engines are complex mixtures of a multitude of different types of hydrocarbon species. Attempting numerical simulations of combustion of real fuels with all of the hydrocarbon species included is highly unrealistic. Thus, a surrogate model approach is generally adopted, which involves choosing a few representative hydrocarbon species whose overall behavior mimics the characteristics of the

Krishnasamy Anand; youngchul Ra; Rolf Reitz; Bruce G Bunting

2011-01-01

208

QUANTITATIVE ANALYSIS OF POLYNUCLEAR AROMATIC HYDROCARBONS IN LIQUID FUELS  

EPA Science Inventory

Polynuclear aromatic hydrocarbons (PNAs), formed in combustion processes with liquid hydrocarbon fuels, contribute to mobile source exhaust emissions. Because correlation between PNA levels in automobile exhaust and pre-existent PNAs in fuel has been demonstrated in previous work...

209

Measurement of spray combustion processes  

SciTech Connect

A free jet configuration was chosen for measuring noncombusting spray fields and hydrocarbon-air spray flames in an effort to develop computational models of the dynamic interaction between droplets and the gas phase and to verify and refine numerical models of the entire spray combustion process. The development of a spray combustion facility is described including techniques for laser measurements in spray combustion environments and methods for data acquisition, processing, displaying, and interpretation.

Peters, C.E.; Arman, E.F.; Hornkohl, J.O.; Farmer, W.M.

1984-04-01

210

Gas-Phase Mercury Conversion in H2, O2, Chloro C1Hydrocarbon, and NOx Combustion Effluent from Use of an Elementary Kinetic Mechanism  

Microsoft Academic Search

Emissions of gaseous mercury from combustion sources and their control are a major environmental concern facing power generators. The removal of mercury by conversion to mercury halides is evaluated by use of an elementary reaction mechanism that is developed from fundamental principles of thermodynamics and statistical mechanics. Thermochemical properties have been calculated for needed reaction intermediates using CBS-QB3 and density

Itsaso Auzmendi Murua; Joseph W. Bozzelli

2010-01-01

211

Chemistry of the natural atmosphere  

Microsoft Academic Search

The fundamental principles of atmospheric chemistry are examined in a textbook for graduate science students. Topics addressed include the bulk composition, structure, and dynamics of the atmosphere; photochemical processes and elementary reactions; the chemistry of the stratosphere; tropospheric chemistry and the methane oxidation cycle; and ozone in the troposphere. Consideration is given to volatile hydrocarbons and halocarbons, the atmospheric aerosol,

Peter Warneck

1988-01-01

212

Numerical study of premixed HCCI engine combustion and its sensitivity to computational mesh and model uncertainties  

NASA Astrophysics Data System (ADS)

This study used a numerical model to investigate the combustion process in a premixed iso-octane homogeneous charge compression ignition (HCCI) engine. The engine was a supercharged Cummins C engine operated under HCCI conditions. The CHEMKIN code was implemented into an updated KIVA-3V code so that the combustion could be modelled using detailed chemistry in the context of engine CFD simulations. The model was able to accurately simulate the ignition timing and combustion phasing for various engine conditions. The unburned hydrocarbon emissions were also well predicted while the carbon monoxide emissions were under predicted. Model results showed that the majority of unburned hydrocarbon is located in the piston-ring crevice region and the carbon monoxide resides in the vicinity of the cylinder walls. A sensitivity study of the computational grid resolution indicated that the combustion predictions were relatively insensitive to the grid density. However, the piston-ring crevice region needed to be simulated with high resolution to obtain accurate emissions predictions. The model results also indicated that HCCI combustion and emissions are very sensitive to the initial mixture temperature. The computations also show that the carbon monoxide emissions prediction can be significantly improved by modifying a key oxidation reaction rate constant.

Kong, Song-Charng; Reitz, Rolf D.

2003-06-01

213

Fuel property effects on engine combustion processes. Final report  

SciTech Connect

A major obstacle to improving spark ignition engine efficiency is the limitations on compression ratio imposed by tendency of hydrocarbon fuels to knock (autoignite). A research program investigated the knock problem in spark ignition engines. Objective was to understand low and intermediate temperature chemistry of combustion processes relevant to autoignition and knock and to determine fuel property effects. Experiments were conducted in an optically and physically accessible research engine, static reactor, and an atmospheric pressure flow reactor (APFR). Chemical kinetic models were developed for prediction of species evolution and autoignition behavior. The work provided insight into low and intermediate temperature chemistry prior to autoignition of n-butane, iso-butane, n-pentane, 1-pentene, n-heptane, iso-octane and some binary blends. Study of effects of ethers (MTBE, ETBE, TAME and DIPE ) and alcohols (methanol and ethanol) on the oxidation and autoignition of primary reference fuel (PRF) blends.

Cernansky, N.P.; Miller, D.L.

1995-04-27

214

Combustion of JP8 in Laminar Premixed Flames.  

National Technical Information Service (NTIS)

Experimental and numerical studies are carried out to develop a surrogate that can reproduce selected aspects of combustion of JP-8. Surrogate fuels are defined as mixtures of few hydrocarbon compounds with combustion characteristics similar to those of c...

K. Seshadri

2008-01-01

215

Planar laser-induced-fluorescence imaging measurements of OH and hydrocarbon fuel fragments in high-pressure spray-flame combustion.  

PubMed

Planar laser-induced fluorescence images of OH have been obtained in liquid-fueled spray flames burning heptane, ethanol, and methanol over a range of pressures from 0.1 to 1.0 MPa. In addition to the OH fluorescence, a nonresonant fluorescence interference that increased rapidly with pressure was detected. Examination of the spectrum of this interference indicates that it arises from hydrocarbon fuel-fragment species in the fuel-rich zones of the flame. The pressure dependence of the fluorescence signal is examined in both steady-state and time-dependent analyses, and a model for evaluation of pressure effects and quenching variations in quantitative imaging measurements in nonpremixed flame environments is presented. The results indicate that increased combustor pressure results in a rapid rise of the volume fraction of hydrocarbon fragments and a decrease in the OH volume fraction. PMID:21060473

Allen, M G; McManus, K R; Sonnenfroh, D M; Paul, P H

1995-09-20

216

Characteristics of coal/light hydrocarbon slurries in spray combustion. Semi-annual progress report, 1 September 1980-28 February 1981  

SciTech Connect

This report summarizes the progress made during the first six months of the grant period. The status of each of the three major task areas is discussed: the atomization study, the analytical droplet model, and the combustion study. The time-period has been used primarily to design and begin fabrication of the experimental atomization and combustion facilities. No data is presented in either of these areas. Significant progress has been made in the development of the numerical droplet model. The results of a preliminary parametric study are presented for a single coal particle in a one-millimeter methanol droplet. The importance of gas phase velocity and coal particle diameter bringing the solid material to the droplet surface is discussed.

Grosshandler, W.L.; Crowe, C.T.; Chung, J.N.

1981-03-06

217

The correlation between in-situ, real-time aerosol photoemission intensity and particulate polycyclic aromatic hydrocarbon concentration in combustion aerosols  

Microsoft Academic Search

Aerosol photoemission (APE) has been found to be an excellent surrogate measure of particulate PAH concentration in combustion aerosols under a variety of laboratory and field conditions. Samples of oil stove, automobile exhaust, and urban air particulate matter were concurrently analyzed for aerosol photoemission intensity and particulate PAH concentration. In-situ, real-time analysis of the particulate matter was performed by UV-induced

K. M. Hart; R. McDow; W. Giger; D. Steiner; H. Burtscher

1993-01-01

218

Theoretical studies of combustion chemistry  

SciTech Connect

This paper discusses the mechanism of radical-radical reactions in flames. The reactions of atomic hydrogen with the formyl radical and atomic oxygen with acetylene are discussed as well as energy relaxation in carbonyl sulfide. 1 fig.

Harding, L.B.; Wagner, A.F.; Davis, M.J.; Eades, R.A.; Bair, R.A.; Dunning, T.H. Jr.

1985-01-01

219

Model Reduction for Combustion Chemistry  

Microsoft Academic Search

\\u000a The description of chemically reacting systems leads very often to reaction mechanisms with far above hundred chemical species\\u000a (and, therefore, to more than a hundred partial differential equations), which possibly react within more than a thousand\\u000a of elementary reactions. These kinetic processes cover time scales from nanoseconds to seconds. Due to these scaling problems\\u000a the detailed simulation of three-dimensional turbulent

Dimitris A. Goussis; Ulrich Maas

220

REVIEW OF CRITERIA FOR VAPOR-PHASE HYDROCARBONS  

EPA Science Inventory

Information on vapor-phase hydrocarbons presented in this document covers basic atmospheric chemistry relative to secondary products, especially ozone; sources and emissions; ambient air concentrations; relationship of precursor hydrocarbons to resultant ozone levels in ambient a...

221

Laser Ionization Studies of Hydrocarbon Flames.  

NASA Astrophysics Data System (ADS)

Resonance-enhanced multiphoton ionization (REMPI) and laser induced fluorescence (LIF) are applied as laser based flame diagnostics for studies of hydrocarbon combustion chemistry. rm CH_4/O_2, C _2H_4/O_2, and rm C_2H_6/O_2 low pressure ( ~20 Torr), stoichiometric burner stabilized flat flames are studied. Density profiles of intermediate flame species, existing at ppm concentrations, are mapped out as a function of distance from the burner head. Profiles resulting from REMPI and LIF detection are obtained for HCO, CH_3, H, O, OH, CH, and CO flame radicals. The above flame systems are computer modeled against currently accepted combustion mechanisms using the Chemkin and Premix flame codes developed at Sandia National Laboratories. The modeled profile densities show good agreement with the experimental results of the CH_4/O_2 flame system, thus confirming the current C1 kinetic flame mechanism. Discrepancies between experimental and modeled results are found with the C2 flames. These discrepancies are partially amended by modifying the rate constant of the rm C_2H_3+rm O_2 to H_2CO + HCO reaction. The modeled results computed with the modified rate constant strongly suggest that the kinetics of several or possibly many reactions in the C2 mechanism need refinement.

Bernstein, Jeffrey Scott

222

The effect of strain rate on polycyclic aromatic hydrocarbon (PAH) formation in acetylene diffusion flames  

SciTech Connect

Acetylene is a ubiquitous combustion intermediate that is also believed to be the major precursor for aromatic, polycyclic aromatic hydrocarbon (PAH), and soot formation in both hydrocarbon and halogenated hydrocarbon flames. However, in spite of its important role as a flame intermediate, the detailed chemical structures of acetylene diffusion flames have not been studied in the past. Here the detailed chemical structures of counterflow diffusion flames of acetylene at strain rates of 37.7 and 50.3 s{sup -1} are presented. Both flames possessed the same carbon density of 0.37 g/L corresponding to an acetylene mole fraction of 0.375 in argon on the fuel side, and an oxygen mole fraction of 0.22 in argon on the oxidizer side. Concentration profiles of a large number of major, minor, and trace species, including a wide spectrum of aromatics and PAH, have been determined by direct sampling from flames using a heated quartz microprobe coupled to an online gas chromatograph/mass selective detector (GC/MSD). Temperature profiles were made using a thermocouple and the rapid insertion technique. Although the major species concentrations were nearly the same in the two flames, the mole fraction profiles of trace combustion by-products were significantly lower in the higher-strain-rate flame, by nearly two orders of magnitude for PAH. These comparative results provide new information on the trace chemistries of acetylene flames and should be useful for the development and validation of detailed chemical kinetic mechanisms describing the formation of toxic by-products in the combustion of hydrocarbons and halogenated hydrocarbons. (author)

Yamamoto, Manabu; Duan, Shici; Senkan, Selim [Department of Chemical Engineering, University of California, Los Angeles, CA 90095 (United States)

2007-11-15

223

Combustion aerosols: factors governing their size and composition and implications to human health.  

PubMed

Particulate matter (PM) emissions from stationary combustion sources burning coal, fuel oil, biomass, and waste, and PM from internal combustion (IC) engines burning gasoline and diesel, are a significant source of primary particles smaller than 2.5 microns (PM2.5) in urban areas. Combustion-generated particles are generally smaller than geologically produced dust and have unique chemical composition and morphology. The fundamental processes affecting formation of combustion PM and the emission characteristics of important applications are reviewed. Particles containing transition metals, ultrafine particles, and soot are emphasized because these types of particles have been studied extensively, and their emissions are controlled by the fuel composition and the oxidant-temperature-mixing history from the flame to the stack. There is a need for better integration of the combustion, air pollution control, atmospheric chemistry, and inhalation health research communities. Epidemiology has demonstrated that susceptible individuals are being harmed by ambient PM. Particle surface area, number of ultrafine particles, bioavailable transition metals, polycyclic aromatic hydrocarbons (PAH), and other particle-bound organic compounds are suspected to be more important than particle mass in determining the effects of air pollution. Time- and size-resolved PM measurements are needed for testing mechanistic toxicological hypotheses, for characterizing the relationship between combustion operating conditions and transient emissions, and for source apportionment studies to develop air quality plans. Citations are provided to more specialized reviews, and the concluding comments make suggestions for further research. PMID:11055157

Lighty, J S; Veranth, J M; Sarofim, A F

2000-09-01

224

Real-time quantitative analysis of combustion-generated polycyclic aromatic hydrocarbons by resonance-enhanced multiphoton ionization time-of-flight mass spectrometry  

SciTech Connect

We have combined resonance-enhanced multiphoton ionization (REMPI) time-of-flight mass spectrometry with on-line flame sampling to determine the centerline concentrations of naphthalene, fluorene, and anthracene in a pure methane + oxygen/argon (1:5) diffusion flame. Naphthalene concentrations between 100 parts per billion by volume (ppbV) and 6 parts per million by volume (ppmV) and fluorene concentrations below 50 ppbV are determined using one-color REMPI on jet-cooled samples extracted from the flame; anthracene concentrations in the 5-40 ppbV range are determined using two-color REMPI. The REMPI ion signals are converted to absolute concentrations in real time by performing gas-phase standard additions to the flame sample. Isomer-selective detection of larger polycyclic aromatic hydrocarbons, such as perylene and benzo[a]pyrene, is possible using the two-color REMPI approach. 38 refs., 8 figs.

Gittins, C.M.; Rohlfing, E.A. [Sandia National Lab., Livermore, CA (United States); Castaldi, M.J.; Senkan, S.M. [Univ. of California, Los Angeles, CA (United States)

1997-02-01

225

HC quench layer formation in combustion processes. Technical progress report, September-December 1979  

SciTech Connect

The project is aimed at understanding wall quenching and other processes responsible for surface generated hydrocarbons in combustion under engine-like conditions. The study concerns the effects of turbulence on the evolution of hydrocarbons. At the conclusion of the program, significant new experimental information will have been generated and an analytical model of the fluid mechanics and some aspects of the chemistry of quenching will be formulated. The work is divided into three tasks: (1) combustion bomb experiments to measure the effect of turbulence on the chemical species near the cold surface; combustion bomb experiments, using a similar turbulence generating device, to fully characterize the flow and turbulence in the vicinity of the quenching surface, and an analytical study to characterize fluid mechanical scales of interest in the boundary layer and to find an analytical solution to describe the evolution of the layer. The major accomplishments to date are (i) demonstration of the feasibility of single shot sampling valve operation and gas analysis in the Ford bomb under laminar combustion conditions, (ii) formulation of design rationale for turbulence generation scheme and bomb geometry, and (iii) formulation of an approach to modeling turbulent boundary layer conditions.

Lavoie, G A

1980-02-01

226

Model correlations for ozone, reactive nitrogen, and peroxides for Nashville in comparison with measurements: Implications for O3-NOx-hydrocarbon chemistry  

Microsoft Academic Search

We present an analysis of correlations between O3, NOx reaction products (NOz), and peroxides in photochemical models for polluted environments in comparison with measurements in the vicinity of Nashville, Tennessee. This analysis is associated with the use of O3\\/NOz, H2O2\\/NOz, and similar ratios as indicators for the relative impact of NOx and hydrocarbons (volatile organic compounds, VOC) on ozone formation.

Sanford Sillman; Dongyang He; Margaret R. Pippin; Peter H. Daum; Daniel G. Imre; Lawrence I. Kleinman; Jai Hoon Lee; Judith Weinstein-Lloyd

1998-01-01

227

ReaxFF reactive force field for molecular dynamics simulations of hydrocarbon oxidation.  

PubMed

To investigate the initial chemical events associated with high-temperature gas-phase oxidation of hydrocarbons, we have expanded the ReaxFF reactive force field training set to include additional transition states and chemical reactivity of systems relevant to these reactions and optimized the force field parameters against a quantum mechanics (QM)-based training set. To validate the ReaxFF potential obtained after parameter optimization, we performed a range of NVT-MD simulations on various hydrocarbon/O2 systems. From simulations on methane/O2, o-xylene/O2, propene/O2, and benzene/O2 mixtures, we found that ReaxFF obtains the correct reactivity trend (propene > o-xylene > methane > benzene), following the trend in the C-H bond strength in these hydrocarbons. We also tracked in detail the reactions during a complete oxidation of isolated methane, propene, and o-xylene to a CO/CO2/H2O mixture and found that the pathways predicted by ReaxFF are in agreement with chemical intuition and our QM results. We observed that the predominant initiation reaction for oxidation of methane, propene, and o-xylene under fuel lean conditions involved hydrogen abstraction of the methyl hydrogen by molecular oxygen forming hydroperoxyl and hydrocarbon radical species. While under fuel rich conditions with a mixture of these hydrocarbons, we observed different chemistry compared with the oxidation of isolated hydrocarbons including a change in the type of initiation reactions, which involved both decomposition of the hydrocarbon or attack by other radicals in the system. Since ReaxFF is capable of simulating complicated reaction pathways without any preconditioning, we believe that atomistic modeling with ReaxFF provides a useful method for determining the initial events of oxidation of hydrocarbons under extreme conditions and can enhance existing combustion models. PMID:18197648

Chenoweth, Kimberly; van Duin, Adri C T; Goddard, William A

2008-01-16

228

Reactions of Iron Atoms with Unsaturated Hydrocarbons.  

National Technical Information Service (NTIS)

Reactions of iron atoms with unsaturated hydrocarbons are described to further illustrate the chemistry of metal atoms, and the synthesis of several novel organometallic compounds by the codeposition techniques are reported. (Author)

D. L. Williams-Smith I. R. Wolf P. S. Skell

1972-01-01

229

Combustion leftovers  

Microsoft Academic Search

Combustion processes almost never completely exhaust all of the available fuel. In this paper, we will consider three combustion scenarios (back-to-back premixed flames in stagnation point flow, travelling combustion waves, and microgravity spherical flame balls) and show how to calculate the amount of fuel which will be left over no matter how long we allow the combustion processes to continue.

R. O Weber; G. N Mercer; H. S Sidhu

2002-01-01

230

Stability of supported metal and supported metal oxide combustion catalysts  

Microsoft Academic Search

Catalysts used for high-temperature combustion of light hydrocarbons must maintain high activity over long time intervals by avoiding excessive sintering and deactivation in the hot and corrosive combustion environment. The sintering resistance and chemical stability of catalytically active phases is a key technical problem that must be solved for the development of commercially viable combustion catalysts. All noble metals and

Jon G. McCarty; M. Gusman; D. M. Lowe; D. L. Hildenbrand; K. N. Lau

1999-01-01

231

Fundamental Investigations of Surface Discharges Over Dielectric Liquids for Ignition and Combustion of Fuels.  

National Technical Information Service (NTIS)

Nowadays a problem of effective ignition and combustion of fuels is facing a development of new aircraft generation. Our team has undertaken investigation of ignition of different hydrocarbon materials (including heavy hydrocarbons and alcohol) in conditi...

A. F. Aleksandrov

2007-01-01

232

Accelerating the Computation of Detailed Chemical Reaction Kinetics for Simulating Combustion of Complex Fuels  

SciTech Connect

Combustion of hydrocarbon fuels has been a very challenging scientific and engineering problem due to the complexity of turbulent flows and hydrocarbon reaction kinetics. There is an urgent need to develop an efficient modeling capability to accurately predict the combustion of complex fuels. Detailed chemical kinetic models for the surrogates of fuels such as gasoline, diesel and JP-8 consist of thousands of chemical species and Arrhenius reaction steps. Oxygenated fuels such as bio-fuels and heavier hydrocarbons, such as from newer fossil fuel sources, are expected to have a much more complex chemistry requiring increasingly larger chemical kinetic models. Such models are beyond current computational capability, except for homogeneous or partially stirred reactor type calculations. The advent of highly parallel multi-core processors and graphical processing units (GPUs) promises a steep increase in computational performance in the coming years. This paper will present a software framework that translates the detailed chemical kinetic models to high-performance code targeted for GPU accelerators.

Sankaran, R.; Grout, R.

2012-01-01

233

Accelerating the Computation of Detailed Chemical Reaction Kinetics for Simulating Combustion of Complex Fuels  

SciTech Connect

Combustion of hydrocarbon fuels has been a very challenging scientific and engineering problem due to the complexity of turbulent flows and hydrocarbon reaction kinetics. There is an urgent need to develop an efficient modeling capability to accurately predict the combustion of complex fuels. Detailed chemical kinetic models for the surrogates of fuels such as gasoline, diesel and JP-8 consist of thousands of chemical species and Arrhenius reaction steps. Oxygenated fuels such as bio-fuels and heavier hydrocarbons, such as from newer fossil fuel sources, are expected to have a much more complex chemistry requiring increasingly larger chemical kinetic models. Such models are beyond current computational capability, except for homogeneous or partially stirred reactor type calculations. The advent of highly parallel multi-core processors and graphical processing units (GPUs) promises a steep increase in computational performance in the coming years. This paper will present a software framework that translates the detailed chemical kinetic models to high- performance code targeted for GPU accelerators.

Grout, Ray W [ORNL

2012-01-01

234

Availability analysis of hydrogen\\/natural gas blends combustion in internal combustion engines  

Microsoft Academic Search

Possibly one of the most significant advantages that hydrogen may have as a fuel is its potential for increased second-law efficiency, due to fundamental differences in the mechanism of entropy generation during combustion with respect to the usual hydrocarbon-based fuels. A computational investigation of this effect is pursued for the case of mixtures of hydrogen and natural gas combusting in

C. D. Rakopoulos; M. A. Scott; D. C. Kyritsis; E. G. Giakoumis

2008-01-01

235

Laboratory weathering of combusted oil shale  

Microsoft Academic Search

The objective of this study was to examine the mineralogy and leachate chemistry of three combusted oil shales (two Green River Formation and one New Albany) in a laboratory weathering environment using the humidity cell technique. The mineralogy of the combusted western oil shales (Green River Formation) is process dependent. In general, processing resulted in the formation of anhydrite, lime,

Essington

2009-01-01

236

Combustion engineering  

SciTech Connect

This book is an introduction to combustion science. It discusses general aspects of combustion processes and deals with combustion of premixed mixtures and covers basic concepts of flame propagation, including the flame structure, burning velocity, flame stability, and the Rankine-Hugoniot equations. The book also deals with diffusive combustion, covering laminar and turbulent diffusion flames. Explosions and detonations, including ideal and nonideal explosions, and detonation wave structure are addressed. The determination of the burned gas states is discussed.

Ohtake, K.; Fujiwara, T.

1985-01-01

237

Mild Combustion  

Microsoft Academic Search

The Mild Combustion is characterized by both an elevated temperature of reactants and low temperature increase in the combustion process. These features are the results of several technological demands coming from different application fields. This review paper aims to collect information which could be useful in understanding the fundamentals and applications of Mild Combustion. The information in this field are

Antonio Cavaliere; Mara de Joannon

2004-01-01

238

Soot Formation in Hydrocarbon/Air Laminar Jet Diffusion Flames.  

National Technical Information Service (NTIS)

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 potent...

P. B. Sunderland G. M. Faeth

1994-01-01

239

Manifold methods for methane combustion  

SciTech Connect

Objective is to develop a new method for studying realistic chemistry in turbulent methane combustion with NO{sub x} mechanism. The realistic chemistry is a simplification to a more detailed chemistry based on the manifold method; accuracy is determined by interaction between the transport process and the chemical reaction. In this new (tree) method, probability density function or partially stirred reactor calculations are performed. Compared with the reduced mechanism, manifold, and tabulation methods, the new method overcomes drawbacks of the reduced mechanism method and preserves the advantages of the manifold method. Accuracy is achieved by specifying the size of the cell.

Yang, B.; Pope, S.B. [Cornell Univ., Ithaca, NY (United States)

1995-12-31

240

Hydrocarbon Chemistry in the Atmospheres of Titan and the Outer Planets: a Product Study of the CH3 + C2H3 and the C2H3 + C2H3 Reactions  

NASA Astrophysics Data System (ADS)

Reactions of the C2H3 radical play a prominent role in the hydrocarbon chemistry of the atmospheres of Titan and all the outer planets. An important reaction of C2H3 in these atmospheric systems is CH3 + C2H3 (1). The self reaction C2H3 + C2H3 (2), while of minor importance in atmospheric models, is a complicating secondary reaction in the study of CH3 + C2H3. We have determined the product branching ratios at low pressure (1.3 mbar He) and at T = 298 and 200 K for the C2H3 + C2H3 and the CH3 + C2H3 reactions. The only data available for both of these reactions is at T = 298 K and at rather high pressure (130 mbar). The measurements were performed in a discharge flow system coupled with collision-free sampling to a mass spectrometer operated at low electron energies. For the vinyl self reaction we measured the following product channel yields: C2H3 + C2H3 = C2H2 + C2H4, Gamma_ {2a} = 1.00; C2H3 + C2H3 = C4H6 (1,3-butadiene), Gamma_ {2b} < 0.01 at both T = 298 K and 200 K. For the methyl + vinyl reaction we measure : CH3 + C2H3 = C2H2 + CH4, Gamma_ {1a} = 0.90 at T= 298 K and 0.68 at T = 200 K; CH3 + C2H3 = C3H6 (propylene), Gamma_ {2b} = 0.10 at T = 298 K and 0.32 at T = 200 K. Future photochemical models of the outer planets and satellites should use the more appropriate low temperature/low pressure data. The disproportionation channel (Gamma_ {a}) for all three reactions reforms C2H2 while the combination reaction (Gamma_ {b}) leads to the larger hydrocarbon species C2H4, C3H6 and C4H6. The competition between the disproportionation and combination channels as a function of temperature and pressure has a pronounced effect on the chemical composition of planetary atmospheres as a function of altitude.

Stief, L. J.; Thorn, R. P., Jr.; Payne, W. A.; Chillier, X. F.; Nesbitt, F. L.

1997-07-01

241

Brookhaven National Laboratory: Chemistry Department  

NSDL National Science Digital Library

At this website, the Brookhaven National Laboratory presents its chemistry research dealing primarily with imaging and neuroscience, charge transfer for energy conversion, chemistry with ionizing radiation, catalysis and surface science, nanoscience, combustion, and nuclear chemistry. Within each category, users can find instructive text and supportive images about the specific projects and the leading researchers. Visitors can learn about the Beamline U7A at the National Synchrotron Light Source, the Laser-Electron Accelerator Facility (LEAF), the Positron Emission Tomography (PET) Facility, and other exceptional research facilities. The website features histories of the chemistry department and of the Brookhaven National Laboratory.

242

Fundamental combustion and diagnostics research at Sandia. Progress report, April-June 1980  

SciTech Connect

The combustion research emphasizes basic research into fundamental problems associated with combustion. The overall program addresses detailed chemistry of combustion, fundamental processes associated with laminar and turbulent flames, development of research techniques specifically applicable to combustion environments, and operation of the user-oriented Combustion Research Facility. The first section of this report contains activities in Combustion Research, the second section contains activities in Molecular Physics and Spectroscopy, and the third section contains activities in Diagnostics Research.

Gusinow, M.A. (ed.)

1980-09-01

243

Combustion chamber and thermal vapor stream producing apparatus and method  

DOEpatents

A new and improved method and apparatus for burning a hydrocarbon fuel for producing a high pressure thermal vapor stream comprising steam and combustion gases for injecting into a subterranean formation for the recovery of liquefiable minerals therefrom, wherein a high pressure combustion chamber having multiple refractory lined combustion zones of varying diameters is provided for burning a hydrocarbon fuel and pressurized air in predetermined ratios injected into the chamber for producing hot combustion gases essentially free of oxidizing components and solid carbonaceous particles. The combustion zones are formed by zones of increasing diameters up a final zone of decreasing diameter to provide expansion zones which cause turbulence through controlled thorough mixing of the air and fuel to facilitate complete combustion. The high pressure air and fuel is injected into the first of the multiple zones where ignition occurs with a portion of the air injected at or near the point of ignition to further provide turbulence and more complete combustion.

Sperry, John S. (Houston, TX); Krajicek, Richard W. (Sugar Land, TX); Cradeur, Robert R. (Spring, TX)

1978-01-01

244

Fundamental studies of fuel chemistry as related to internal combustion engine phenomena. Technical progress report, July 1, 1988--June 30, 1989  

SciTech Connect

The present research effort was initiated with the intent of providing substantially improved insights (through homogeneous gas phase kinetic studies at different constant pressures) to the fuel chemistry issues important to autoignition in engines. The conditions of the proposed experiments were chosen to represent those similar to the engine parameters under knocking conditions: temperatures in the range of 700--1,100K, pressures from one to approximately 20 atmospheres and stoichiometries around one. A major part of the proposed research has been to design and construct a variable pressure flow reactor facility in which a range of reaction pressures, and in fact, lower reaction temperatures could be accessed. The reactor facility design and construction are nearly complete, and initial testing has begun to compare the overall experimental operating characteristics of the reactor with the design parameters. Experiments on Isobutene/oxygen mixtures have also been conducted in the existing atmospheric pressure flow reactor at about 1,150 K and in an equivalence ratio range of pyrolysis with about 100 ppm oxygen background to 0.42. A detailed kinetic model has been developed to interpret the pyrolysis and oxidation characteristics. 89 refs.

Dryer, F.L.; Brezinsky, K.

1989-07-01

245

Computational Combustion  

SciTech Connect

Progress in the field of computational combustion over the past 50 years is reviewed. Particular attention is given to those classes of models that are common to most system modeling efforts, including fluid dynamics, chemical kinetics, liquid sprays, and turbulent flame models. The developments in combustion modeling are placed into the time-dependent context of the accompanying exponential growth in computer capabilities and Moore's Law. Superimposed on this steady growth, the occasional sudden advances in modeling capabilities are identified and their impacts are discussed. Integration of submodels into system models for spark ignition, diesel and homogeneous charge, compression ignition engines, surface and catalytic combustion, pulse combustion, and detonations are described. Finally, the current state of combustion modeling is illustrated by descriptions of a very large jet lifted 3D turbulent hydrogen flame with direct numerical simulation and 3D large eddy simulations of practical gas burner combustion devices.

Westbrook, C K; Mizobuchi, Y; Poinsot, T J; Smith, P J; Warnatz, J

2004-08-26

246

Identification of isomeric hydrocarbons by Rydberg photoelectron spectroscopy  

Microsoft Academic Search

Many saturated and unsaturated organic hydrocarbons can assume multiple isomeric forms. At high temperatures, the identification of such isomers is difficult with conventional spectroscopic techniques, posing a challenge to the exploration of important processes such as the combustion of hydrocarbons. A recently developed technology using resonance enhanced multi-photon ionization via Rydberg states shows promise as an analytical technique, because the

Job D. Cardoza; Fedor M. Rudakov; Nils Hansen; Peter M. Weber

2008-01-01

247

Combustion heater  

Microsoft Academic Search

A wood burning combustion heater comprises a combustion chamber for long logs arranged to burn down from one end to the other in cigar-like fashion, an after-burner tube arrayed above and essentially parallel to the elongated logs with the air and burned gasses following an S-shaped path through the combustion chamber and out through the exhaust tube, an after-burner within

Kalenian

1980-01-01

248

Atmospheric polycyclic aromatic hydrocarbons: Source attribution, emission factors and regulation  

Microsoft Academic Search

There is an increasing concern about the occurrence of polycyclic aromatic hydrocarbons (PAHs) in the environment as they are ubiquitous in ambient air and some of them are among the strongest known carcinogens. PAHs and their derivatives are produced by the incomplete combustion of organic material arising, partly, from natural combustion such as forest and volcanic eruption, but with the

Khaiwal Ravindra; Ranjeet Sokhi; René Van Grieken

2008-01-01

249

Organic chemistry of the atmosphere  

SciTech Connect

This book reviews the information currently available regarding the chemistry of organic compounds in the atmosphere. Topics discussed include methods for collecting organic compounds from the atmosphere, the influence of organic compounds on indoor and outdoor air quality, the chemistry of polycyclic aromatic hydrocarbons, environmental tobacco smoke, organic compounds in rainwater, organic oxysulfur compounds, and the effect of organic compounds on visibility. Many of these topics presented have never been reviewed or have never appeared together in a single volume.

Hansen, L.D. (Brigham Young Univ., Provo, UT (United States). Dept. of Chemistry)

1991-01-01

250

Advanced Chemistry Basins Model  

SciTech Connect

The DOE-funded Advanced Chemistry Basin model project is intended to develop a public domain, user-friendly basin modeling software under PC or low end workstation environment that predicts hydrocarbon generation, expulsion, migration and chemistry. The main features of the software are that it will: (1) afford users the most flexible way to choose or enter kinetic parameters for different maturity indicators; (2) afford users the most flexible way to choose or enter compositional kinetic parameters to predict hydrocarbon composition (e.g., gas/oil ratio (GOR), wax content, API gravity, etc.) at different kerogen maturities; (3) calculate the chemistry, fluxes and physical properties of all hydrocarbon phases (gas, liquid and solid) along the primary and secondary migration pathways of the basin and predict the location and intensity of phase fractionation, mixing, gas washing, etc.; and (4) predict the location and intensity of de-asphaltene processes. The project has be operative for 36 months, and is on schedule for a successful completion at the end of FY 2003.

William Goddard; Mario Blanco; Lawrence Cathles; Paul Manhardt; Peter Meulbroek; Yongchun Tang

2002-11-10

251

Polycyclic aromatic hydrocarbons: environmental pollution and bioremediation  

Microsoft Academic Search

Polycyclic aromatic hydrocarbons (PAHs) are widely distributed and relocated in the environment as a result of the incomplete combustion of organic matter. Many PAHs and their epoxides are highly toxic, mutagenic and\\/or carcinogenic to microorganisms as well as to higher systems including humans. Although various physicochemical methods have been used to remove these compounds from our environment, they have many

Sudip K Samanta; Om V Singh; Rakesh K Jain

2002-01-01

252

Combustion process  

SciTech Connect

A combustion catalyst containing both manganese and antimony in a temperature range of above about 1260/sup 0/ F. has been found to result in unexpactedly high CO/sub 2//CO ratios in the regenerator off-gas when CO is combusted.

McKay, D.L.

1984-07-03

253

Mid-IR laser absorption diagnostics for hydrocarbon vapor sensing in harsh environments  

NASA Astrophysics Data System (ADS)

Fuel/air stoichiometry is an important parameter in modern combustion devices because it has a profound influence on efficiency, power, and pollutant formation. As engine technologies continue to advance, diagnostics and sensors are becoming essential for studying fundamental combustion processes and characterizing performance of combustion-based engines. Optical-absorption diagnostics have been used previously to probe various species in these environments and to infer quantities such as concentration, temperature, pressure, and velocity. However, there have been only a limited number of demonstrations of optical diagnostics for hydrocarbon fuels. This thesis describes the development of mid-IR optical-absorption sensors for time-resolved measurements of hydrocarbon species to infer critical parameters such as concentration and temperature. These sensors provide the necessary sensitivity and time resolution for measurements in shock tubes, pulse detonation engines, and internal combustion engines. Different aspects of the research conducted are summarized below. An FTIR spectrometer is used to measure the temperature-dependent absorption spectra of a selection of hydrocarbon species and blended fuels in the ˜3.3 mum region of the fundamental C-H stretching vibration. This spectroscopic library provides the first high-temperature spectral information for many of the species studied and facilitates development of sensitive diagnostics for various applications. This unique database also enables modelling of the absorption spectra of blended fuels such as gasoline. An ethylene and propane diagnostic is designed for measuring fuel concentration in a pulse detonation engine using a fixed-wavelength helium-neon laser. Time-resolved measurements during fired tests of a repetitively pulsed engine reveal non-ideal cycle-to-cycle interactions that cause a substantial amount of fuel to leave the engine unburned. By quantifying the fuel loading and identifying the amount of unburned fuel, engine performance can be characterized and future engine designs can be improved to utilize all of the fuel supplied to the engine. Simultaneous measurement of absorption at two wavelengths is used as a basis for hydrocarbon detection in severe environments. A novel wavelength-tunable mid-IR laser is modified to rapidly switch between two wavelengths, improving the versatility of this laser system. The two-wavelength technique is then exploited to measure vapor concentration while rejecting interferences such as scattering from liquid droplets and absorption from other species. This two-wavelength laser is also used to simultaneously determine temperature and vapor concentration. These techniques, in combination with the library of temperature-dependent hydrocarbon spectra, lay the groundwork necessary to develop fuel diagnostics for laboratory experiments and tests in pulse detonation engines and internal combustion engines. The temperature-dependent spectroscopy of gasoline is examined to develop a sensor for fuel/air ratio in an internal combustion engine. A wavelength was selected for good sensitivity to gasoline concentration. A spectroscopic model is developed that uses the relative concentrations of five structural classes to predict the absorption spectrum of gasoline samples with varying composition. The model is tested on 21 samples of gasoline for temperatures ranging from 300 to 1200 K, showing good agreement between model and measurements over the entire temperature range. Finally, a two-wavelength diagnostic was developed to measure the post-evaporation temperature and n-dodecane concentration in an aerosol-laden shock tube. The experimental data validate a model which calculates the effects of shock-wave compression on a two-phase mixture. The measured post-shock temperature and vapor concentration compare favorably for gas-phase and aerosol experiments. The agreement between the two fuel-loading techniques verifies that this aerosol shock tube can be used to study hydrocarbon chemistry for low-vapor-pressure compounds. The diagnos

Klingbeil, Adam Edgar

254

Hydrocarbon Exploration  

NSDL National Science Digital Library

To detect the hydrocarbon reservoir, structure traps should be detected. Seismic reflection profiles can be used to illustrate the structure image for the subsurface layers and hence, find out structure traps for oil. key words: Seismic reflection profiles, structural traps, oil potentialities,...

Tarabees, Elhamy

255

Numerical analysis of supersonic combustion ramjet with upstream fuel injection  

Microsoft Academic Search

This paper describes possible fuel injection scheme for airbreathing engines that use hydrocarbon fuels. The basic idea is to inject fuel at the spike tip of the supersonic inlet to achieve mixing and combustion efficiency with a limited length combustion chamber. A numerical code, able to solve the full Navier-Stokes equations in turbulent and reacting flows, is employed to obtain

Raffaele Savino; Giuseppe Pezzella

2003-01-01

256

Sandia Combustion Research Program: Annual report, 1986  

SciTech Connect

This report presents research results of the past year, divided thematically into some ten categories. Publications and presentations arising from this work are included in the appendix. Our highlighted accomplishment of the year is the announcement of the discovery and demonstration of the RAPRENOx process. This new mechanism for the elimination of nitrogen oxides from essentially all kinds of combustion exhausts shows promise for commercialization, and may eventually make a significant contribution to our nation's ability to control smog and acid rain. The sections of this volume describe the facility's laser and computer system, laser diagnostics of flames, combustion chemistry, reacting flows, liquid and solid propellant combustion, mathematical models of combustion, high-temperature material interfaces, studies of engine/furnace combustion, coal combustion, and the means of encouraging technology transfer. 182 refs., 170 figs., 12 tabs.

Not Available

1986-01-01

257

Sampling and analysis protocol for assessing organic emissions from stationary combustion sources in exposure evaluation division combustion studies. Methods manual  

Microsoft Academic Search

The sampling and analysis methods described in the report were specifically designed for use in an ongoing nationwide survey of emissions of organic pollutants from stationary combustion sources. The primary focus of the survey is on polynuclear aromatic hydrocarbons (PAHs) and polychlorinated aromatic hydrocarbons including polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs). To date, these procedures have

J. S. Stanley; C. L. Haile; A. M. Small; E. P. Olson

1982-01-01

258

Kinetic double-layer model of aerosol surface chemistry and gas-particle interactions (K2-SURF): degradation of polycyclic aromatic hydrocarbons exposed to O3, NO2, H2O, OH and NO3  

NASA Astrophysics Data System (ADS)

We present a kinetic double-layer surface model (K2-SURF) that describes the degradation of polycyclic aromatic hydrocarbons (PAHs) on aerosol particles exposed to ozone, nitrogen dioxide, water vapor, hydroxyl and nitrate radicals. The model is based on multiple experimental studies of PAH degradation and on the PRA framework (Pöschl et al., 2007) for aerosol and cloud surface chemistry and gas-particle interactions. For a wide range of substrates, including solid and liquid organic and inorganic substances (soot, silica, sodium chloride, octanol/decanol, organic acids, etc.), the concentration- and time-dependence of the heterogeneous reaction between PAHs and O3 can be efficiently described with a Langmuir-Hinshelwood-type mechanism. Depending on the substrate material, the Langmuir adsorption constants for O3 vary over three orders of magnitude (Kads,O3?10-15-10-13 cm3), and the second-order rate coefficients for the surface layer reaction of O3 with different PAH vary over two orders of magnitude (kSLR,PAH,O3?10-18-10-17 cm2 s-1). The available data indicate that the Langmuir adsorption constants for NO2 are similar to those of O3, while those of H2O are several orders of magnitude smaller (Kads,H2O?10-18-10-17 cm3). The desorption lifetimes and adsorption enthalpies inferred from the Langmuir adsorption constants suggest chemisorption of NO2 and O3 - possibly in the form of O atoms - and physisorption of H2O. The K2-SURF model enables the calculation of ozone uptake coefficients, ?O3, and of PAH concentrations in the quasi-static particle surface layer. Competitive adsorption and chemical transformation of the surface (aging) lead to a strong non-linear dependence of ?O3 on time and gas phase composition, with different characteristics under dilute atmospheric and concentrated laboratory conditions. Under typical ambient conditions, ?O3 of PAH-coated aerosol particles are expected to be in the range of 10-6-10-5. At ambient temperatures, NO2 alone does not efficiently degrade PAHs, but it was found to accelerate the degradation of PAHs exposed to O3. The accelerating effect can be attributed to highly reactive NO3 radicals formed in the gas phase or on the surface. Estimated second-order rate coefficients for O3-NO2 and PAH-NO3 surface layer reactions are in the range of 10-17-10-16 cm2 s-1 and 10-15-10-12 cm2 s-1, respectively. The chemical half-life of PAH is expected to range from a few minutes on the surface of soot to multiple hours on organic and inorganic solid particles and days on liquid particles. On soot, the degradation of particle-bound PAHs in the atmosphere appears to be dominated by a surface layer reaction with adsorbed ozone. On other substrates, it is likely dominated by gas-surface reactions with OH or NO3 radicals (Eley-Rideal-type mechanism). To our knowledge, K2-SURF is the first atmospheric process model describing multiple types of parallel and sequential surface reactions between multiple gaseous and particle-bound chemical species. It illustrates how the general equations of the PRA framework can be simplified and adapted for specific reaction systems, and we suggest that it may serve as a basis for the development of a general master mechanism of aerosol and cloud surface chemistry.

Shiraiwa, M.; Garland, R. M.; Pöschl, U.

2009-09-01

259

Kinetic double-layer model of aerosol surface chemistry and gas-particle interactions (K2-SURF): Degradation of polycyclic aromatic hydrocarbons exposed to O3, NO2, H2O, OH and NO3  

NASA Astrophysics Data System (ADS)

We present a kinetic double-layer surface model (K2-SURF) that describes the degradation of polycyclic aromatic hydrocarbons (PAHs) on aerosol particles exposed to ozone, nitrogen dioxide, water vapor, hydroxyl and nitrate radicals. The model is based on multiple experimental studies of PAH degradation and on the PRA framework (Pöschl-Rudich-Ammann, 2007) for aerosol and cloud surface chemistry and gas-particle interactions. For a wide range of substrates, including solid and liquid organic and inorganic substances (soot, silica, sodium chloride, octanol/decanol, organic acids, etc.), the concentration- and time-dependence of the heterogeneous reaction between PAHs and O3 can be efficiently described with a Langmuir-Hinshelwood-type mechanism. Depending on the substrate material, the Langmuir adsorption constants for O3 vary over three orders of magnitude (Kads,O3 ? 10-15-10-13 cm3), and the second-order rate coefficients for the surface layer reaction of O3 with different PAH vary over two orders of magnitude (kSLR,PAH,O3 ? 10-18-10-17 cm2 s-1). The available data indicate that the Langmuir adsorption constants for NO2 are similar to those of O3, while those of H2O are several orders of magnitude smaller (Kads,H2O ? 10-18-10-17 cm3). The desorption lifetimes and adsorption enthalpies inferred from the Langmuir adsorption constants suggest chemisorption of NO2 and O3 and physisorption of H2O. Note, however, that the exact reaction mechanisms, rate limiting steps and possible intermediates still remain to be resolved (e.g., surface diffusion and formation of O atoms or O3- ions at the surface). The K2-SURF model enables the calculation of ozone uptake coefficients, ?O3, and of PAH concentrations in the quasi-static particle surface layer. Competitive adsorption and chemical transformation of the surface (aging) lead to a strong non-linear dependence of ?O3 on time and gas phase composition, with different characteristics under dilute atmospheric and concentrated laboratory conditions. Under typical ambient conditions, ?O3 of PAH-coated aerosol particles are expected to be in the range of 10-6-10-5. At ambient temperatures, NO2 alone does not efficiently degrade PAHs, but it was found to accelerate the degradation of PAHs exposed to O3. The accelerating effect can be attributed to highly reactive NO3 radicals formed in the gas phase or on the surface. Estimated second-order rate coefficients for O3-NO2 and PAH-NO3 surface layer reactions are in the range of 10-17-10-16 cm2 s-1 and 10-15-10-12 cm2 s-1, respectively. The chemical half-life of PAHs is expected to range from a few minutes on the surface of soot to multiple hours on organic and inorganic solid particles and days on liquid particles. On soot, the degradation of particle-bound PAHs in the atmosphere appears to be dominated by a surface layer reaction with adsorbed ozone. On other substrates, it is likely dominated by gas-surface reactions with OH or NO3 radicals (Eley-Rideal-type mechanism). To our knowledge, K2-SURF is the first atmospheric process model describing multiple types of parallel and sequential surface reactions between multiple gaseous and particle-bound chemical species. It illustrates how the general equations of the PRA framework can be simplified and adapted for specific reaction systems, and we suggest that it may serve as a basis for the development of a general master mechanism of aerosol and cloud surface chemistry.

Shiraiwa, M.; Garland, R. M.; Pöschl, U.

2009-12-01

260

Gas turbine alternative fuels combustion characteristics  

NASA Astrophysics Data System (ADS)

An experimental investigation was conducted to obtain combustion performance and exhaust pollutant concentrations for specific synthetic hydrocarbon fuels. Baseline comparison fuels used were gasoline and diesel fuel number two. Testing was done over a range of fuel to air mass ratios, total mass flow rates, and input combustion air temperatures in a flame-tube-type gas turbine combustor. Test results were obtained in terms of released heat and combustion gas emission values. The results were comparable to those obtained with the base fuels with variations being obtained with changing operating conditions. The release of carbon particles during the tests was minimal.

Rollbuhler, R. James

1989-02-01

261

Alternative energy sources II; Proceedings of the Second Miami International Conference, Miami Beach, Fla., December 10-13, 1979. Volume 7 - Hydrocarbon conversion  

NASA Astrophysics Data System (ADS)

Consideration is given to such topics as coal gasification and liquefaction, the combustion of alcohol fuels, hydrocarbon upgrading and combustion technology, novel engines using hydrocarbon fuel, and hydrocarbons economics and planning. Particular papers are presented on the role of high-Btu coal gasification technology, ethanol from municipal cellulosic wastes, the fluidized bed combustion of coal, the behavior of gas distribution equipment in hydrogen service, and the economics of advanced technologies for electricity generation from coal.

Veziroglu, T. N.

262

Combustion systems  

SciTech Connect

This patent describes an external combustion engine such as a Stirling engine and the like, having an external heat system housing in which is defined a heater space, a hollow liner formed of a ceramic material disposed in the heater space and defining a combustion chamber. Biasing means are coupled to a first end of the liner and coupled with the housing so as to maintain the liner in the heater space while dampening transmission of vibration in the housing to the liner.

Kralick, J.

1986-03-04

263

Combustion Mechanisms of Heterogeneous Solid Propellants.  

National Technical Information Service (NTIS)

The bulk of the research on this contract was concerned with the mechanisms that cause plateau burning of ammonium perchlorate/hydrocarbon (AP/ HC) propellants. The long range goal is to identify the steps in the combustion process that dominate overall b...

E. W. Price J. M. Freeman R. Jeenu R. K. Sigman S. R. Chakravarthy

2000-01-01

264

Gas turbine combustion and emission control  

Microsoft Academic Search

The fundamentals of combustion are discussed in the context of gaseous and liquid fuels and gas turbine fuels. Methods for reducing the emission of pollutants in gas turbines are considered. These emissions are carbon monoxide, unburnt hydrocarbons, smoke\\/soot, nitrogen oxides, sulphur oxides, and carbon dioxide. The focus is on nitrogen oxides. The general principles of combustor and burner design are

B. Schetter

1993-01-01

265

Direct catalytic oxidation of halogenated hydrocarbons  

SciTech Connect

Halogenated hydrocarbon emission are facing increasingly stringent controls due to both regulatory constraints and public concerns. A new catalytic conversion process is described which can catalytically oxidize halogenated hydrocarbons selectively to hydrochloric acid and carbon dioxide. The hydrochloric acid can then be removed in a simple brine scrubber. No other products of incomplete oxidation are observed at 5 ppb levels of sensitivity. Mixtures of VOCs and halogenated hydrocarbons are converted by the catalyst equally easily, without the aldehyde formation found with nobel metal catalysis. The low temperature catalytic combustion of halogenated hydrocarbons is shown to have inherent advantages relative to a thermal incinerator, the principal destruction alternative In addition, the catalytic oxidation process is cost effective and robust at small scale, allowing application for remote locations or for multiple installations in a plant near each emission source.

Kittrell, J.R.; Quinlan, C.W.; Eldridge, J.W. (KSE, Inc., Amherst, MA (United States))

1991-08-01

266

The impact of nonmethane hydrocarbon compounds on tropospheric photochemistry  

Microsoft Academic Search

Nonmethane hydrocarbons (NMHC) play an important role in global scale tropospheric photochemistry. The representation of NMHC chemistry in three-dimensional tropospheric chemistry transport models requires a highly parameterized description of only the most important processes, as the number of reactions and compounds involved is very large. In this paper a chemical scheme is presented, based on the Carbon Bond Mechanism 4

Sander Houweling; Frank Dentener; Jos Lelieveld

1998-01-01

267

Partial combustion of electrical insulation fluids: Final report  

SciTech Connect

Recurring fire incidents involving transformers have led to a desire to acquire information about the combustion products that may be generated not only in situations of complete combustion, but also in incidents when limited oxygen is present and combustion is incomplete or partial. This report details some results from investigations designed to identify the products of incomplete combustion of five types of dielectric fluids commonly used in transformers, as alternatives to askarels. These fluids are tetrachloroethylene, trichlorotrifluoroethane, polydimethylsiloxane (silicone fluid), mineral oil, and a high temperature hydrocarbon. The investigation of these fluids was begun with a theoretical study of the thermodynamic equilibrium over a range of temperatures and pressures. The experimental program was carried out in two separate studies, one which involved heating the fluid from room temperature to 1000/sup 0/C and another which used injection into a furnace that was preheated to 1000/sup 0/C. The air level in each chamber was chosen to provide 70% and 30% of the oxygen for stoichiometric total combustion. None of the combustions produced detectable chlorinated or polycyclic aromatic hydrocarbon particulates. Detectable quantities of chlorine and hydrogen chloride were produced from tetrachloroethylene as well as a small amount of dichloroacetylene. Trichlorotrifluoroethane produced a number of fluorocarbon compounds as well as hydrogen fluoride. Silicone fluid produced substantial quantities of a solid material, believed to be silicon dioxide and like the two hydrocarbon fluids, produced several combustible hydrocarbon gases as well as carbon dioxide and carbon monoxide. 9 refs., 19 figs., 12 tabs.

Claiborne, C.C.

1987-07-01

268

Nitration of polynuclear aromatic hydrocarbons in coal combustors and exhaust streams. Quarterly report, September 1, 1991--December 31, 1991  

SciTech Connect

Nitro-polynuclear aromatic hydrocarbons (nitro-PAH) are the predominant mutagens on respirable particles from coal-fired boilers. Since nitro-PAH are not primary products of coal devolatilization, their formation must involve secondary chemistry at elevated temperatures. However, it is not known where in the combustion or exhaust processes they form, which reaction species are involved, or how concentrations are influenced by operating conditions. Results from this study will help to relate the environmental impact of mutagenic emissions to boiler firing strategies. The objectives of this three-year project are to (1) identify the conditions which promote the nitration of PAH during primary combustion, reburning, hot gas cleanup, and particulate removal; and (2) investigate the potential relationship between NO{sub x} abatement and PAH nitration. A novel coal flow reactor burning actual coal products operates over the domains of heating rates, temperatures, fuel-equivalence ratios, and residence times in utility boilers. A fluidized bed will be built for studies of simulated hot gas cleanup at lower temperatures. Gas chromatography with chemiluminescence detection will measure the aggregate amount of nitro groups present, to determine when nitro-PAH first appear, and how nitration is affected by the operating conditions. Tars from primary and secondary pyrolysis and oxidative pyrolysis will be fractionated into chain hydrocarbons, polynuclear aromatics, oxygenated species, and a basic fraction, so that their ring number distribution can be monitored with high performance liquid chromatography.

Yu, Liya; Dadamio, J.; Hildemann, L.; Niksa, S.

1992-08-01

269

Nitration of polynuclear aromatic hydrocarbons in coal combustors and exhaust streams. [Determination of conditions of nitration, reactions,etc  

SciTech Connect

Nitro-polynuclear aromatic hydrocarbons (nitro-PAH) are the predominant mutagens on respirable particles from coal-fired boilers. Since nitro-PAH are not primary products of coal devolatilization, their formation must involve secondary chemistry at elevated temperatures. However, it is not known where in the combustion or exhaust processes they form, which reaction species are involved, or how concentrations are influenced by operating conditions. Results from this study will help to relate the environmental impact of mutagenic emissions to boiler firing strategies. The objectives of this three-year project are to (1) identify the conditions which promote the nitration of PAH during primary combustion, reburning, hot gas cleanup, and particulate removal; and (2) investigate the potential relationship between NO{sub x} abatement and PAH nitration. A novel coal flow reactor burning actual coal products operates over the domains of heating rates, temperatures, fuel-equivalence ratios, and residence times in utility boilers. A fluidized bed will be built for studies of simulated hot gas cleanup at lower temperatures. Gas chromatography with chemiluminescence detection will measure the aggregate amount of nitro groups present, to determine when nitro-PAH first appear, and how nitration is affected by the operating conditions. Tars from primary and secondary pyrolysis and oxidative pyrolysis will be fractionated into chain hydrocarbons, polynuclear aromatics, oxygenated species, and a basic fraction, so that their ring number distribution can be monitored with high performance liquid chromatography.

Yu, Liya; Dadamio, J.; Hildemann, L.; Niksa, S.

1992-08-01

270

Green Chemistry  

NSDL National Science Digital Library

This special feature page from the American Chemical Society (ACS) showcases the up-and-coming field of "green chemistry," that is, the development of chemical products and processes that eliminate or reduce the use and generation of hazardous substances. A list of principles behind green chemistry, a searchable bibliography of green chemistry references, green chemistry links (including conferences), and an online preview of the ACS-published book Real-World Cases in Green Chemistry are all found at the site. Five video clips on green chemistry from the standpoint of academia, industry, and small business are also featured (Windows Media Player). This page comes from ACS's Green Chemistry Project, a three-year educational project to develop and disseminate green chemistry educational materials for graduate and undergraduate chemistry students. Check back often for updates.

2002-01-01

271

Kinetic double-layer model of aerosol surface chemistry and gas-particle interactions (K2-SURF): Degradation of polycyclic aromatic hydrocarbons exposed to O3, NO2, H2O, OH and NO3  

NASA Astrophysics Data System (ADS)

We present a kinetic double-layer surface model (K2-SURF) that describes the degradation of polycyclic aromatic hydrocarbons (PAHs) on aerosol particles exposed to ozone, nitrogen dioxide, water vapor, hydroxyl and nitrate radicals [1]. The model is based on multiple experimental studies of PAH degradation and on the Pöschl-Rudich-Ammann (PRA) framework [2] for aerosol and cloud surface chemistry and gas-particle interactions. For a wide range of substrates, including solid and liquid organic and inorganic substances (soot, silica, sodium chloride, octanol/decanol, organic acids, etc.), the concentration- and time-dependence of the heterogeneous reaction between PAHs and O3 can be efficiently described with a Langmuir-Hinshelwood-type mechanism. Depending on the substrate material, the Langmuir adsorption constants for O3 vary over three orders of magnitude, and the second-order rate coefficients for the surface layer reaction of O3 with different PAH vary over two orders of magnitude. The available data indicate that the Langmuir adsorption constants for NO2 are similar to those of O3, while those of H2O are several orders of magnitude smaller. The desorption lifetimes and adsorption enthalpies suggest chemisorption of NO2 and O3 and physisorption of H2O. Note, however, that the exact reaction mechanisms, rate limiting steps and possible intermediates still remain to be resolved (e.g., surface diffusion and formation of O atoms or O3- ions at the surface). The K2-SURF model enables the calculation of ozone uptake coefficients, ?O3, and of PAH concentrations in the quasi-static particle surface layer. Competitive adsorption and chemical transformation of the surface (aging) lead to a strong non-linear dependence of ?O3 on time and gas phase composition, with different characteristics under dilute atmospheric and concentrated laboratory conditions. Under typical ambient conditions, ?O3 of PAH-coated aerosol particles are expected to be in the range of 10-6 - 10-5. At ambient temperatures, NO2 alone does not efficiently degrade PAHs, but it was found to accelerate the degradation of PAHs exposed to O3. The accelerating effect can be attributed to highly reactive NO3 radicals formed in the gas phase or on the surface. Estimated second-order rate coefficients for O3-NO2 and PAH-NO3 surface layer reactions are in the range of 10-17 - 10-16 cm2 s-1 and 10-15 - 10-12 cm2 s-1, respectively. The chemical half-life of PAHs is expected to range from a few minutes on the surface of soot to multiple hours on organic and inorganic solid particles and days on liquid particles. On soot, the degradation of particle-bound PAHs in the atmosphere appears to be dominated by a surface layer reaction with adsorbed ozone. On other substrates, it is likely dominated by gas-surface reactions with OH or NO3 radicals (Eley-Rideal-type mechanism). To our knowledge, K2-SURF is the first atmospheric process model describing multiple types of parallel and sequential surface reactions between multiple gaseous and particle-bound chemical species. It illustrates how the general equations of the PRA framework can be simplified and adapted for specific reaction systems. References: [1] Shiraiwa et al., Atmos. Chem. and Phys., 9, 9571-9586 (2009). [2] Pöschl et al., Atmos. Chem. and Phys., 7, 5989-6023 (2007).

Shiraiwa, Manabu; Garland, Rebecca M.; Pöschl, Ulrich

2010-05-01

272

Spherical Combustion Layer in a TNT Explosion  

SciTech Connect

A theoretical model of combustion in spherical TNT explosions at large Reynolds, Peclet and Damk hler numbers is described. A key feature of the model is that combustion is treated as material transformations in the Le Chatelier plane, rather than ''heat release''. In the limit considered here, combustion is concentrated on thin exothermic sheets (boundaries between fuel and oxidizer). The products expand along the sheet, thereby inducing vorticity on either side of the sheet that continues to feed the process. The results illustrate the linking between turbulence (vorticity) and exothermicity (dilatation) in the limit of fast chemistry thereby demonstrating the controlling role that fluid dynamics plays in such problems.

Kuhl, A L; Ferguson, R E

2001-12-09

273

Composition, distribution, and characterization of polycyclic aromatic hydrocarbons in soil in Linfen, China  

SciTech Connect

A total of 10 surface soil samples representing the entire area of Linfen City were collected and analyzed for the presence of 16 polycyclic aromatic hydrocarbons. The total polycyclic aromatic hydrocarbon concentration ranged from 1.1 to 63.7 {mu} g g{sup -1}. Analysis of the sources of contamination revealed that polycyclic aromatic hydrocarbons in the soil were derived from combustion sources. Specifically, the primary source of polycyclic aromatic hydrocarbons was coal combustion, but the samples were also effected to varying degrees by traffic emissions. Furthermore, increased levels of contamination were observed in northeast Linfen due to the distribution of industrial plants.

Fu, S.; Cheng, H.X.; Liu, Y.H.; Xia, X.J.; Xu, X.B. [Chinese Academy of Sciences, Beijing (China)

2009-02-15

274

Biofuels combustion.  

PubMed

This review describes major features of current research in renewable fuels derived from plants and from fatty acids. Recent and ongoing fundamental studies of biofuel molecular structure, oxidation reactions, and biofuel chemical properties are reviewed, in addition to combustion applications of biofuels in the major types of engines in which biofuels are used. Biofuels and their combustion are compared with combustion features of conventional petroleum-based fuels. Two main classes of biofuels are described, those consisting of small, primarily alcohol, fuels (particularly ethanol, n-butanol, and iso-pentanol) that are used primarily to replace or supplement gasoline and those derived from fatty acids and used primarily to replace or supplement conventional diesel fuels. Research efforts on so-called second- and third-generation biofuels are discussed briefly. PMID:23298249

Westbrook, Charles K

2013-01-04

275

High-temperature corrosion in advanced combustion systems  

Microsoft Academic Search

Conceptual designs of advanced combustion systems that utilize coal as a feedstock require high temperature furnaces and heat transfer surfaces capable of operation at much elevated temperatures than those prevalent in current coal-fired power plants. The combination of elevated temperatures and hostile combustion environments necessitate development\\/application of advanced ceramic materials in these designs. The present paper characterizes the chemistry of

K. Natesan; M. Yanez-Herrero; C. Fornasieri

1993-01-01

276

NOX EMISSIONS MODELING IN BIOMASS COMBUSTION GRATE FURNACES  

Microsoft Academic Search

A new flamelet combustion model is developed for the modeling of NOx emissions in biomass grate furnaces. The model describes the combustion chemistry using premixed flamelets. The chemical system is mapped on two controlling variables: the mixture fraction and a reaction progress variable. The species mass fractions and temperature are tabulated as functions of the controlling variables in a pre-processing

B. A. Albrecht; R. J. M. Bastiaans; J. A. van Oijen; L. P. H. de Goey

277

A detailed kinetic mechanism including methanol and nitrogen pollutants relevant to the gas-phase combustion and pyrolysis of biomass-derived fuels  

SciTech Connect

A detailed chemical kinetic mechanism for the simulation of the gas-phase combustion and pyrolysis of biomass-derived fuels was compiled by assembling selected reaction subsets from existing mechanisms (parents). The mechanism, here referred to as ''AaA,'' includes reaction subsets for the oxidation of hydrogen (H{sub 2}), carbon monoxide (CO), light hydrocarbons (C{sub 1} and C{sub 2}), and methanol (CH{sub 3}OH). The mechanism also takes into account reaction subsets of nitrogen pollutants, including the reactions relevant to staged combustion, reburning, and selective noncatalytic reduction (SNCR). The AaA mechanism was validated against suitable experimental data from the literature. Overall, the AaA mechanism gave more accurate predictions than three other mechanisms of reference, although the reference mechanisms performed better occasionally. The predictions from AaA were also found to be consistent with the predictions of its parent mechanisms within most of their range of validity, thus transferring the validity of the parents to the inheriting mechanism (AaA). In parametric studies the AaA mechanism predicted that the effect of methanol on combustion and pollutants is often similar to that of light hydrocarbons, but it also showed that there are important exceptions, thus suggesting that methanol should be taken into account when simulating biomass combustion. To our knowledge, the AaA mechanism is currently the only mechanism that accounts for the chemistry of methanol and nitrogen relevant to the gas-phase combustion and pyrolysis of biomass-derived fuels. (author)

Coda Zabetta, Edgardo; Hupa, Mikko [Aabo Akademi Process Chemistry Centre, Piispankatu 8, FI-20500 Turku (Finland)

2008-01-15

278

Stratified combustion type engine  

Microsoft Academic Search

The present invention relates to a stratified combustion type engine comprising an engine cylinder, a main combustion chamber located above the cylinder, an injection nozzle for injecting auxiliary fuel towards the combustion chamber, and an open pre-combustion chamber provided within the combustion chamber for locally holding and vaporizing the flow of auxiliary fuel from the injection nozzle. The pre-combustion chamber

Kamiya

1977-01-01

279

Stratified combustion type engine  

Microsoft Academic Search

A stratified combustion type engine is described that is comprised of an engine cylinder, a main combustion chamber located above the cylinder, an injection nozzle for injecting auxiliary fuel towards the combustion chamber, and an open pre-combustion chamber provided within the combustion chamber for locally holding and vaporizing the flow of auxiliary fuel from the injection nozzle. The pre-combustion chamber

Kamiya

1978-01-01

280

Chemistry Notes.  

ERIC Educational Resources Information Center

Presents background information, laboratory procedures, classroom materials/activities, and chemistry experiments. Topics include sublimation, electronegativity, electrolysis, experimental aspects of strontianite, halide test, evaluation of present and future computer programs in chemistry, formula building, care of glass/saturated calomel…

School Science Review, 1983

1983-01-01

281

Chemistry Notes.  

ERIC Educational Resources Information Center

|Presents background information, laboratory procedures, classroom materials/activities, and chemistry experiments. Topics include sublimation, electronegativity, electrolysis, experimental aspects of strontianite, halide test, evaluation of present and future computer programs in chemistry, formula building, care of glass/saturated calomel…

School Science Review, 1983

1983-01-01

282

Role of black carbon in the organic chemistry of atmospheric aerosols  

SciTech Connect

Black carbon plays a significant role in the physics and chemistry of atmospheric aerosols because of its optical absorptivity, adsorption capacity, and surface characteristics. These properties affect the composition and chemical behavior of the associated organic material. Gas chromatographic and mass spectral studies indicate that particulate organic material contains unburned and partially oxidized fuel hydrocarbons, polynuclear aromatic hydrocarbons, and polyfunctional oxygenated compounds which may be formed in the atmosphere by reactions of hydrocarbons with atmospheric or pollutant gases. Carbonaceous aerosols were characterized using combustion evolved gas analysis (thermal analysis) with simultaneous optical attenuation measurements and selective solvent extraction. Thermograms of urban aerosols typically exhibit three broad peaks when evolved CO/sub 2/ concentration is plotted versus heating temperature. Sample thermograms are shown. Field and characterization studies indicate that the ratios of secondary to primary carbon in urban particulate matter are similar for samples collected in Berkeley, Los Angeles, and New York City, irrespective of the level of photochemical activity at the sampling sites. The fraction of black carbon to total carbon in urban carbonaceous particles is approximately constant, independent of sampling location or time of year.

Gundel, L.A.; Dod, R.L.; Hansen, A.D.A.; Rosen, H.; Chang, S.G.; Novakov, T.

1981-04-01

283

Exhaust after-treatment system with in-cylinder addition of unburnt hydrocarbons  

DOEpatents

Certain exhaust after-treatment devices, at least periodically, require the addition of unburnt hydrocarbons in order to create reductant-rich exhaust conditions. The present disclosure adds unburnt hydrocarbons to exhaust from at least one combustion chamber by positioning, at least partially within a combustion chamber, a mixed-mode fuel injector operable to inject fuel into the combustion chamber in a first spray pattern with a small average angle relative to a centerline of the combustion chamber and a second spray pattern with a large average angle relative to the centerline of the combustion chamber. An amount of fuel is injected in the first spray pattern into a non-combustible environment within the at least one combustion chamber during at least one of an expansion stroke and exhaust stroke. The exhaust with the unburnt amount of fuel is moved into an exhaust passage via an exhaust valve.

Coleman, Gerald N. (Corby, GB); Kesse, Mary L. (Peoria, IL)

2007-10-30

284

Aviation combustion toxicology: an overview.  

PubMed

Aviation combustion toxicology is a subspecialty of the field of aerospace toxicology, which is composed of aerospace and toxicology. The term aerospace, that is, the environment extending above and beyond the surface of the Earth, is also used to represent the combined fields of aeronautics and astronautics. Aviation is another term interchangeably used with aerospace and aeronautics and is explained as the science and art of operating powered aircraft. Toxicology deals with the adverse effects of substances on living organisms. Although toxicology borrows knowledge from biology, chemistry, immunology, pathology, physiology, and public health, the most closely related field to toxicology is pharmacology. Economic toxicology, environmental toxicology, and forensic toxicology, including combustion toxicology, are the three main branches of toxicology. In this overview, a literature search for the period of 1960-2007 was performed and information related to aviation combustion toxicology collected. The overview included introduction; combustion, fire, and smoke; smoke gas toxicity; aircraft material testing; fire gases and their interactive effects; result interpretation; carboxyhemoglobin and blood cyanide ion levels; pyrolytic products of aircraft engine oils, fluids, and lubricants; and references. This review is anticipated to be an informative resource for aviation combustion toxicology and fire-related casualties. PMID:20109297

Chaturvedi, Arvind K

285

Organic Chemistry  

NSDL National Science Digital Library

R. H. Logan, an chemistry instructor at North Lake College, created this introduction to organic chemistry. The introduction covers a eight types of organic compounds, including Alkanes, Alkyl Halides, and Acyl Compounds (forthcoming); Conformational Analysis and Stereoisomerism; and Instrumental Analysis of Organic Compounds, as well an extensive lesson in general chemistry.

286

Forensic Chemistry  

Microsoft Academic Search

“Forensic chemistry” is a broad term that, if taken literally, would encompass most of the functions within a crime laboratory.\\u000a Techniques used in forensic chemistry are also used by the toxicology and trace analysis sections. However, forensic chemistry\\u000a generally refers to controlled substance or drug analysis.

Donnell Christian

287

Forensic Chemistry  

Microsoft Academic Search

Forensic chemistry is unique among chemical sciences in that its research, practice, and presentation must meet the needs of both the scientific and the legal communities. As such, forensic chemistry research is applied and derivative by nature and design, and it emphasizes metrology (the science of measurement) and validation. Forensic chemistry has moved away from its analytical roots and is

Suzanne Bell

2009-01-01

288

Improvement of Coal Combustion Efficiency and Decrease of Harmful Emission Under the Influence of Plasma - Modelling  

Microsoft Academic Search

A numerical study has been undertaken which simulates the process of pulverised coal preparation for combustion using plasmas. Two combustion model s ('fast chemistry' based on one-step fuel transformation into final products, and 'stretched laminar flamelets' with the detailed chemical mechanism for the combust ion of volatiles) are tested and validated with the experimental results. In a preliminary calc ulation,

Z. Jankoski

289

Early events in radiation chemistry and in photoionization  

SciTech Connect

Real-time studies of aliphatic and aromatic hydrocarbons by pulse radiolysis and laser photoionization reveal the chemistry of the ionic species in the condensed phase. The occurrence of radical cation reactions with solvent molecules provides the core mechanism capable of explaining a wide range of observations in photoionization and radiation chemistry. The study of products and transients in photoionization of aromatic solutes in hydrocarbon and alcohol solvent illustrates several details of this ``high-energy`` chemistry. A reaction pathway involving ion-molecule reaction of excited ions is indicated for a series of polycyclic aromatic hydrocarbons photoionized using intense excimer laser (248 and 308 nm) pulses in hydrocarbon and alcohol solutions. We have found that condensed-phase ion-molecule reactions in radiolysis are ubiquitous and we speculate on their overall role in hydrocarbon radiolysis.

Trifunac, A.D.; Loffredo, D.M.; Liu, A.-D.

1992-12-31

290

Early events in radiation chemistry and in photoionization  

SciTech Connect

Real-time studies of aliphatic and aromatic hydrocarbons by pulse radiolysis and laser photoionization reveal the chemistry of the ionic species in the condensed phase. The occurrence of radical cation reactions with solvent molecules provides the core mechanism capable of explaining a wide range of observations in photoionization and radiation chemistry. The study of products and transients in photoionization of aromatic solutes in hydrocarbon and alcohol solvent illustrates several details of this high-energy'' chemistry. A reaction pathway involving ion-molecule reaction of excited ions is indicated for a series of polycyclic aromatic hydrocarbons photoionized using intense excimer laser (248 and 308 nm) pulses in hydrocarbon and alcohol solutions. We have found that condensed-phase ion-molecule reactions in radiolysis are ubiquitous and we speculate on their overall role in hydrocarbon radiolysis.

Trifunac, A.D.; Loffredo, D.M.; Liu, A.-D.

1992-01-01

291

Progress on the Combustion Integrated Rack component of the fluids and Combustion Facility  

NASA Astrophysics Data System (ADS)

The Fluids and Combustion Facility (FCF) is a facility-class payload planned for the International Space Station. It is designed to accommodate a wide variety of investigations encompassing most of the range of microgravity fluid physics and combustion science. The Combustion Integrated Rack component of the FCF is currently scheduled to be launched in 2003 and will operate independently until additional racks of the FCF are launched. The FCF is intended to complete between five and fifteen combustion experiments per year over its planned ten-year lifetime. Combustion areas that may be studied include laminar flames, reaction kinetics, droplet and spray combustion, flame spread, fire and fire suppressants, condensed phase organic fuel combustion, turbulent combustion, soot and polycyclic aromatic hydrocarbons, and flame-synthesized materials. Three different chamber inserts, one each for investigations of droplet, solid fuel, and gaseous fuel combustion, that can accommodate multiple experiments will be used initially so as to maximize the reuse of hardware. The current flight and flight-definition investigations are briefly described. .

Weiland, Karen J.

2000-01-01

292

FIELD SCREENING OF POLYCYCLIC HYDROCARBON CONTAMINATION IN SOIL USING A PORTABLE SYNCHRONOUS SCANNING SPECTROFLUOROMETER  

EPA Science Inventory

Polycyclic aromatic hydrocarbon (PAH) contamination is a considerable problem at various hazardous waste sites. sources of PAH contamination include: incomplete combustion processes, wood preservatives, and the fuel industry. he development of rapid, cost-effective field screenin...

293

CLUSTER CHEMISTRY  

SciTech Connect

Metal cluster chemistry is one of the most rapidly developing areas of inorganic and organometallic chemistry. Prior to 1960 only a few metal clusters were well characterized. However, shortly after the early development of boron cluster chemistry, the field of metal cluster chemistry began to grow at a very rapid rate and a structural and a qualitative theoretical understanding of clusters came quickly. Analyzed here is the chemistry and the general significance of clusters with particular emphasis on the cluster research within my group. The importance of coordinately unsaturated, very reactive metal clusters is the major subject of discussion.

Muetterties, Earl L.

1980-05-01

294

The formation of dioxins in combustion systems  

Microsoft Academic Search

Flame chemistry in incineration systems involves the formation of many organic products of incomplete combustion, including chlorinated species such as polychlorinated biphenyls (PCB), polychlorinated dibenzo-p-dioxins (PCDD), and polychlorinated dibenzofurans (PCDF). Because the latter are of environmental concern, a great deal of research has been expended on understanding their formation. There are two temperature windows in which they can form: the

B. R Stanmore

2004-01-01

295

The phase analysis of coal combustion ashes  

Microsoft Academic Search

The phase composition of coal combustion ashes is important in regard to their potential uses. Here it is shown that a combination of phase separation techniques with X-ray diffraction, thermogravimetric analysis, and conventional chemical analysis, including elemental analysis and wet chemistry, can be used to obtain a fairly complete phase composition. The application of these techniques is illustrated with an

A. P. Iribarne; J. V. Iribarne; E. J. Anthony; J. Blondin

1994-01-01

296

Combustion instability modeling and analysis  

SciTech Connect

It is well known that the two key elements for achieving low emissions and high performance in a gas turbine combustor are to simultaneously establish (1) a lean combustion zone for maintaining low NO{sub x} emissions and (2) rapid mixing for good ignition and flame stability. However, these requirements, when coupled with the short combustor lengths used to limit the residence time for NO formation typical of advanced gas turbine combustors, can lead to problems regarding unburned hydrocarbons (UHC) and carbon monoxide (CO) emissions, as well as the occurrence of combustion instabilities. The concurrent development of suitable analytical and numerical models that are validated with experimental studies is important for achieving this objective. A major benefit of the present research will be to provide for the first time an experimentally verified model of emissions and performance of gas turbine combustors. The present study represents a coordinated effort between industry, government and academia to investigate gas turbine combustion dynamics. Specific study areas include development of advanced diagnostics, definition of controlling phenomena, advancement of analytical and numerical modeling capabilities, and assessment of the current status of our ability to apply these tools to practical gas turbine combustors. The present work involves four tasks which address, respectively, (1) the development of a fiber-optic probe for fuel-air ratio measurements, (2) the study of combustion instability using laser-based diagnostics in a high pressure, high temperature flow reactor, (3) the development of analytical and numerical modeling capabilities for describing combustion instability which will be validated against experimental data, and (4) the preparation of a literature survey and establishment of a data base on practical experience with combustion instability.

Santoro, R.J.; Yang, V.; Santavicca, D.A. [Pennsylvania State Univ., University Park, PA (United States); Sheppard, E.J. [Tuskeggee Univ., Tuskegee, AL (United States). Dept. of Aerospace Engineering

1995-12-31

297

Experimental and kinetic modeling study of combustion of JP-8, its surrogates and reference components in laminar nonpremixed flows  

Microsoft Academic Search

Experimental and numerical studies are carried out to construct reliable surrogates that can reproduce aspects of combustion of JP-8 and Jet-A. Surrogate fuels are defined as mixtures of few hydrocarbon compounds with combustion characteristics similar to those of commercial fuels. The combustion characteristics considered here are extinction and autoignition in laminar non premixed flows. The “reference” fuels used as components

S. Humer; A. Frassoldati; S. Granata; T. Faravelli; E. Ranzi; R. Seiser; K. Seshadri

2007-01-01

298

Polycyclic aromatic hydrocarbons in the diet  

Microsoft Academic Search

Polycyclic aromatic hydrocarbons (PAHs), of which benzo[a]pyrene is the most commonly studied and measured, are formed by the incomplete combustion of organic matter. They are widely distributed in the environment and human exposure to them is unavoidable. A number of them, such as benzo[a]pyrene, are carcinogenic and mutagenic, and they are widely believed to make a substantial contribution to the

David H Phillips

1999-01-01

299

Catalytic cracking of hydrocarbons  

Microsoft Academic Search

This patent describes a fluid catalytic cracking process for nonhydrogenative cracking of hydrocarbons, which cracking process comprises: cofeeding active hot solid zeolite cracking catalyst and crackable hydrocarbon feed to a cracking zone; cracking the feed to hydrocarbon products while depositing coke, nickel and vanadium on the catalyst; disengaging the coked catalyst from the hydrocarbon products; passing the coked catalyst to

G. J. Green; B. K. Huh; T. Y. Yan

1989-01-01

300

Mechanism analysis with ILDMs for H2 combustion on Pd catalysts  

Microsoft Academic Search

This paper explores the usefulness of intrinsic low-dimensional manifolds (ILDMs) for interpreting complex behavior of catalytic combustion chemistry. Thermodynamically consistent surface chemistry with repulsive interaction potentials for some surface species is incorporated with a mean field approach and validated against earlier experimental studies for low temperature combustion of H2 over supported Pd-based catalysts. Two similar surface chemistry mechanisms, modified from

S.-A. S. Reihani; G. S. Jackson

2006-01-01

301

Contrail: A Module from Physical Chemistry On-Line Project  

ERIC Educational Resources Information Center

|The impact of contrails on Earth's climate is researched to understand the active area. It is suggested that the process of contrail formation involves combustion, cooling and ice formation, which are good comprehensive learning exercise for physical chemistry students.|

Chen, Franklin; Zielinski, Theresa Julia; Long, George

2007-01-01

302

Sandia combustion research program: Annual report, 1987  

SciTech Connect

More than a decade ago, in response to a national energy crisis, Sandia proposed to the US Department of Energy a new, ambitious program in combustion research. Our strategy was to apply the rapidly increasing capabilities in lasers and computers to combustion science and technology. Shortly thereafter, the Combustion Research Facility (CRF) was established at Sandia's Livermore location. Designated a ''User Facility,'' the charter of the CRF was to develop and maintain special-purpose resources to support a nationwide initiative--involving US universities, industry, and national laboratories--to improve our understanding and control of combustion. This report includes descriptions of several research projects which have been stimulated by Working Groups and involve the on-site participation of industry scientists. DOE's Industry Technology Fellowship Program has been instrumental in the success of some of the joint efforts. The remainder of this report presents research results of calendar year 1987, separated thematically into nine categories. Refereed journal articles appearing in print during 1987, along with selected other publications, are included at the end of Section 10. In addition to our ''traditional'' research--chemistry, reacting flow, diagnostics, engine combustion, and coal combustion--you will note continued progress in somewhat recent themes: pulse combustion, high temperature materials, and energetic materials, for example. Moreover, we have just started a small, new effort to understand combustion-related issues in the management of toxic and hazardous materials.

Palmer, R.E.; Sanders, B.R.; Ivanetich, C.A. (eds.)

1988-01-01

303

High efficiency detonation internal combustion engine (DICE)  

NASA Astrophysics Data System (ADS)

Controlled detonation combustion could be used in future internal combustion engines to achieve high cycle efficiency and minimize NO(x) formation, if conventional design limitations are removed. An engine is proposed that uses a separate detonation combustion chamber which discharges tangentially into an expansion chamber formed by the piston and cylinder at top dead center. The expansion chamber is designed to efficiently store a portion of the detonation wave's kinetic energy in the form of a vortex, which is subsequently converted into static pressure. The rapid burning, followed by 'leaning' through mixing with air in the vortex chamber, may reduce the formation of NO(x) and unburned hydrocarbons as compared to conventional combustion. The thermodynamic aspects of detonation combustion compared to either constant volume or constant pressure combustion yield a significant increase in combustion compression ratio for fuels such as natural gas. The shock wave propagation through the vortex chamber is described with a shock-capturing finite element Euler flow code supporting the premise of vortex storage and rapid-mixing characteristics.

Loth, Eric; Loth, John; Loth, Frank

1992-07-01

304

Corona chemistry in Titan.  

PubMed

The atmosphere of Titan is constantly bombarded by galactic cosmic rays and Saturnian magnetospheric electrons causing the formation of free electrons and primary ions, which are then stabilized by ion cluster formation and charging of aerosols. These charged particles accumulate in drops in cloud regions of the troposphere. Their abundance can substantially increase by friction, fragmentation or collisions during convective activity. Charge separation occurs with help of convection and gravitational settling leading to development of electric fields within the cloud and between the cloud and the ground. Neutralization of these charged particles leads to corona discharges which are characterized by low current densities. We have therefore, experimentally studied the corona discharge of a simulated Titan's atmosphere (10% methane and 2% argon in nitrogen) at 500 Torr and 298 K by GC-FTIR-MS techniques. The main products have been identified as hydrocarbons (ethane, ethyne, ethene, propane, propene+propyne, cyclopropane, butane, 2-methylpropane, 2-methylpropene, n-butane, 2-butene, 2,2-dimethylpropane, 2-methylbutane, 2-methylbutene, n-pentane, 2,2-dimethylbutane, 2-methylpentane, 3-methylpentane, n-hexane, 2,2-dimethylhexane, 2,2-dimethylpentane, 2,2,3-trimethylbutane, 2,3-dimethylpentane and n-heptane), nitriles (hydrogen cyanide, cyanogen, ethanenitrile, propanenitrile, 2-methylpropanenitrile and butanenitrile) and a highly branched hydrocarbon deposit. We present the trends of hydrocarbons and nitriles formation as a function of discharge time in an ample interval and have derived their initial yields of formation. The results clearly demonstrate that a complex organic chemistry can be initiated by corona processes in the lower atmosphere. Although photochemistry and charged particle chemistry occurring in the stratosphere can account for many of the observed hydrocarbon species in Titan, the predicted abundance of ethene is too low by a factor of 10 to 40. While some ethene will be produced by charged-particle chemistry, the production of ethene by corona processes and its subsequent diffusion into the stratosphere appears to be an adequate source. Because little UV penetrates to the lower atmosphere to destroy the molecules formed there, the corona-produced species may be long-lived and contribute significantly to the composition of the lower atmosphere and surface. PMID:11541887

Navarro-Gonzalez, R; Ramirez, S I; Matrajt, G; Basiuk, V; Basiuk, E

1998-06-01

305

A new technique for measuring gas conversion factors for hydrocarbon mass flowmeters  

NASA Astrophysics Data System (ADS)

A technique for measuring calibration conversion factors for hydrocarbon mass flowmeters was developed. It was applied to a widely used type of commercial thermal mass flowmeter for hydrocarbon gases. The values of conversion factors for two common hydrocarbons measured using this technique are in good agreement with the empirical values cited by the manufacturer. Similar agreements can be expected for all other hydrocarbons. The technique is based on Nernst theorem for matching the partial pressure of oxygen in the combustion product gases with that in normal air. It is simple, quick and relatively safe--particularly for toxic/poisonous hydrocarbons.

Singh, J. J.; Sprinkle, D. R.

1983-08-01

306

Liquid fuel combustion apparatus  

Microsoft Academic Search

This patent describes a vaporized liquid fuel combustion apparatus of the type including: a cylinder defining a combustion chamber, the cylinder having an inlet end for receipt of combustion air and an outlet end for exhausting gaseous combustion products; an end plate covering the inlet end of the cylinder; a blower, including a rotor and a casing, for supplying combustion

K. Sawada; Y. Kimijima; H. Umehara

1986-01-01

307

Gas turbine combustion  

Microsoft Academic Search

This text focuses on the fundamentals of gas turbine combustion, emphasizing combustor design and performance. The material presented is based on the latest research results. Aerodynamic and heat transfer processes in gas turbine combustors as well as the combustion performance parameters of ignition, combustion efficiency, and stability are described. Some of the topics covered are combustion fundamentals; diffusers; aerodynamics; combustion

1983-01-01

308

Autoignition and Combustion of JP-8 and its Surrogates at Moderate Pressures.  

National Technical Information Service (NTIS)

The principal objective of the research is to develop surrogates that will reproduce selected aspects of combustion of JP-8 in laminar non- premixed and premixed flows. Surrogates are mixtures of hydrocarbon compounds. The research was conducted over a pe...

K. Seshadri

2012-01-01

309

Chemical Kinetic Models for HCCI and Diesel Combustion  

SciTech Connect

Hydrocarbon fuels for advanced combustion engines consist of complex mixtures of hundreds or even thousands of different components. These components can be grouped into a number of chemically distinct classes, consisting of n-paraffins, branched paraffins, cyclic paraffins, olefins, oxygenates, and aromatics. Biodiesel contains its own unique chemical class called methyl esters. The fractional amounts of these chemical classes are quite different in gasoline, diesel fuel, oil-sand derived fuels and bio-derived fuels, which contributes to the very different combustion characteristics of each of these types of combustion systems. The objectives of this project are: (1) Develop detailed chemical kinetic models for fuel components used in surrogate fuels for diesel and HCCI engines; (2) Develop surrogate fuel models to represent real fuels and model low temperature combustion strategies in HCCI and diesel engines that lead to low emissions and high efficiency; and (3) Characterize the role of fuel composition on low temperature combustion modes of advanced combustion engines.

Pitz, W J; Westbook, C K; Mehl, M

2008-10-30

310

Problems of providing completeness of the methane-containing block-jet combustion in a rocket-ramjet engine's combustion chamber  

NASA Astrophysics Data System (ADS)

Some problems of methane-containing hydrocarbon fuel combustion are discussed. It seems that reduction of methane burnout zone length is one from main problems of designing new type engine. It is very important at the creation of combustion chambers of a rocket-ramjet engine for prospective space shuttle launch vehicles.

Timoshenko, Valeriy I.; Belotserkovets, Igor S.; Gusinin, Vjacheslav P.

2009-11-01

311

Doing Chemistry  

NSDL National Science Digital Library

This website includes over 150 chemistry experiments in the following areas: Atomic Structure, Bonding, Chemical Reactions, Colligative Properties, Condensed States, Electrochemistry, Equilibrium Gases, Instrumentation, Limiting Reactant and more.

Brooks, David W.

2010-05-25

312

Some Aspects of the Measurement of Polycyclic Aromatic Hydrocarbons in Aqueous Solution  

Microsoft Academic Search

Polycyclic aromatic hydrocarbons (PAH) are formed during pyrolysis or incomplete combustion of organic materials. As a result of an increasing public concern about the contamination of the environment, polycyclic aromatic hydrocarbons are extensively studied compounds. Because PAH are present in effluents from coal firing and advanced coal conversion processes, methods are studied in our laboratory to quantify PAH-emissions.It is known

F. Janssen; J. Kanij

1982-01-01

313

Volatile Hydrocarbon Exposure During In Situ Burning of Crude Oil at Sea  

Microsoft Academic Search

Personal exposure of response workers (and other personnel) to volatile hydrocarbons and benzene was monitored as part of the Newfoundland Offshore Burn Experiment (NOBE), a major oil spill combustion trial organized by Environment Canada and sponsored by over 25 governmental and private organizations from Canada and the United States. Benzene and total petroleum hydrocarbons were monitored using organic vapor monitors

Stephen M. Bowes III

1996-01-01

314

Combustion studies aboard the international space station: Planned experiments and facilities  

NASA Astrophysics Data System (ADS)

The Fluids and Combustion Facility (FCF) is a payload planned for the International Space Station. The facility is designed to accommodate a wide variety of investigations encompassing the range of microgravity fluid physics and combustion science. The combustion areas that may be studied include laminar flames, reaction kinetics, droplet and spray combustion, flame spread, fire and fire suppressants, condensed phase organic fuel combustion, turbulent combustion, soot and polycyclic aromatic hydrocarbons, materials synthesis, and detonations and explosions. The initial experiments will study droplet combustion and solid fuel flammability, ignition, and transition to flame spread. The Combustion Integrated Rack component of the FCF is currently scheduled to be launched in 2002 and will operate independently until the FCF is complete in 2003. The FCF is intended to complete between five and fifteen combustion experiments per year over its planned ten-year lifetime.

Weiland, Karen J.

1999-01-01

315

Factors affecting pore water hydrocarbon concentrations in Puget Sound sediments  

SciTech Connect

Polycyclic aromatic hydrocarbon (PAH) and aliphatic hydrocarbon concentrations have been determined for sediments and associated pore waters collected at 2 sites (11 stations) in Puget Sound, Washington (northwest U.S.A.). These sediments have been contaminated to varying degrees by hydrocarbons from a creosote plant and from various combustion sources. PAH were not detected in pore waters of sediments whose PAH were primarily derived from combustion and natural sources, even though pore water concentrations predicted from sediment concentrations and two-phase equilibrium partitioning models were above detection limits from most PAH. Equilibrium partition coefficients calculated from field aqueous and solid phase data from an area contaminated with creosote agreed with laboratory-derived coefficients to within a factor of +/- 4. Pore water concentrations of creosote-derived aliphatic hydrocarbons increase with increasing concentration in bulk sediments. However, pore water concentrations of natural and contaminant aliphatic hydrocarbons are much higher than predicted by solubility data, possible due to association with nonfilterable dissolved organic matter and colloids. Other major factors controlling hydrocarbon pore water concentrations include differential hydrocarbon sources, specific particle associations and solubility.

Socha, S.B.; Carpenter, R.

1987-05-01

316

Hydrocarbon Analogues of Boron Clusters: Planarity, Aromaticity, and Antiaromaticity  

SciTech Connect

An interesting feature of elemental boron and boron compounds is the occurrence of highly symmetric icosahedral clusters. The rich chemistry of boron is also dominated by three-dimensional cage structures. Despite its proximity to carbon, elemental boron clusters have been scarcely studied experimentally and their structures and chemical bonding have not been fully elucidated. Here we report experimental and theoretical evidence that small boron clusters prefer planar structures and exhibit aromaticity and antiaromaticity according to the Hckel rules, akin to planar hydrocarbons. Aromatic boron clusters possess more circular shapes whereas antiaromatic boron clusters are elongated, analogous to structural distortions of antiaromatic hydrocarbons. The planar boron clusters are thus the only series of molecules other than the hydrocarbons to exhibit size-dependent aromatic and antiaromatic behavior and represent a new dimension of boron chemistry. The stable aromatic boron clusters may exhibit similar chemistries as that of benzene, such as forming sandwich-type metal compounds.

Zhai, Hua-Jin; Boggavarapu, Kiran; Li, Jun; Wang, Lai-Sheng

2003-12-01

317

Chemical Kinetic Modeling of Biofuel Combustion  

NASA Astrophysics Data System (ADS)

Bioalcohols, such as bioethanol and biobutanol, are suitable replacements for gasoline, while biodiesel can replace petroleum diesel. Improving biofuel engine performance requires understanding its fundamental combustion properties and the pathways of combustion. This study's contribution is experimentally validated chemical kinetic combustion mechanisms for biobutanol and biodiesel. Fundamental combustion data and chemical kinetic mechanisms are presented and discussed to improve our understanding of biofuel combustion. The net environmental impact of biobutanol (i.e., n-butanol) has not been studied extensively, so this study first assesses the sustainability of n-butanol derived from corn. The results indicate that technical advances in fuel production are required before commercializing biobutanol. The primary contribution of this research is new experimental data and a novel chemical kinetic mechanism for n-butanol combustion. The results indicate that under the given experimental conditions, n-butanol is consumed primarily via abstraction of hydrogen atoms to produce fuel radical molecules, which subsequently decompose to smaller hydrocarbon and oxygenated species. The hydroxyl moiety in n-butanol results in the direct production of the oxygenated species such as butanal, acetaldehyde, and formaldehyde. The formation of these compounds sequesters carbon from forming soot precursors, but they may introduce other adverse environmental and health effects. Biodiesel is a mixture of long chain fatty acid methyl esters derived from fats and oils. This research study presents high quality experimental data for one large fatty acid methyl ester, methyl decanoate, and models its combustion using an improved skeletal mechanism. The results indicate that methyl decanoate is consumed via abstraction of hydrogen atoms to produce fuel radicals, which ultimately lead to the production of alkenes. The ester moiety in methyl decanoate leads to the formation of low molecular weight oxygenated compounds such as carbon monoxide, formaldehyde, and ketene. The study concludes that the oxygenated molecules in biofuels follow similar combustion pathways to the hydrocarbons in petroleum fuels. The oxygenated moiety's ability to sequester carbon from forming soot precursors is highlighted. However, the direct formation of oxygenated hydrocarbons warrants further investigation into the environmental and health impacts of practical biofuel combustion systems.

Sarathy, Subram Maniam

318

Pulsating Combustion Device Miniaturization.  

National Technical Information Service (NTIS)

The phenomenon of pulsating combustion remains one of the least understood forms of combustion. In this thesis, combustion oscillations are classified into the categories of chamber oscillations, system oscillations, and intrinsic oscillations. Two pulsat...

R. K. Crowe

1976-01-01

319

A Novel Solar Thermal Cycle with Chemical Looping Combustion  

Microsoft Academic Search

In this paper, we have proposed a thermal cycle with the integration of chemical-looping combustion and solar thermal energy with the temperature of about 500-600°C. Chemical-looping combustion may be carried out in two successive reactions between a reduction of hydrocarbon fuel with metal oxides and a reduced metal with oxygen in the air. This loop of chemical reactions is substituted

Hui Hong; Hongguang Jin

2005-01-01

320

Chemistry Notes.  

ERIC Educational Resources Information Center

|Outlines laboratory procedures, demonstrations, teaching suggestions, and content information related to chemistry. Topics include polarizing power; calorimetry and momentum; microcomputers in school chemistry; a constant-volume dispenser for liquids, floating magnets, and crystal lattices; preparation of chromium; and solvent polarity and…

School Science Review, 1981

1981-01-01

321

Polycyclic Aromatic Hydrocarbons (by Ronald G. Harvey)  

Microsoft Academic Search

Ronald G. Harvey. Wiley, VCH: New York, 1997. 667 pp. ISBN 0-471-18608-2. $125. This text is a timely and welcome addition to the ever-growing literature on polycyclic aromatic hydrocarbon (PAH) chemistry and an essential addition to the chemist's library. It is the most comprehensive and complete account of the synthesis and chemical properties of polyarenes to date. The author has

C. F. Murray

1998-01-01

322

Mechanisms for the formation of exhaust hydrocarbons in a single cylinder spark-ignition engine, fueled with deuterium-labeled ortho-, meta-, and para-xylene  

SciTech Connect

Combustion studies in engines have investigated the chemistry leading to the formation in the exhaust of aromatic hydrocarbons from deuterium-labeled isomeric xylenes. These fuels were: ortho-xylene-d{sub 0} and ortho-xylene=d{sub 10} (1:1); para-xylene-d{sub 0} and para-xylene-d{sub 10} (1:1); and meta-xylene-2,4,5,6-d{sub 4}. Isotopic distributions within the exhausted hydrocarbons establish the postflame chemistry involved. There is an isotope effect in the consumption of residual fuel in the postflame region. The residual fuel from each experiment exhibits minimal H-D exchange. Toluene is an intermediate in the formation of ethylbenzene, and is produced through X{sup {sm_bullet}} atom (X{sup {sm_bullet}} = H or D) displacement of methyl radicals from the xylene fuel. Benzene is formed by direct demethylation, but there are other routes. Styrene from o- and p-xylene fuels is formed intramolecularly, probably involving xylylene and methylcycloheptatetraene intermediates. Ethyltoluene is formed by combination of methyl and methylbenzyl radicals.

Gregory, D.; Jackson, R.A. [Univ. of Sussex, Brighton (United Kingdom). School of Chemistry, Physics and Environmental Science; Bennett, P.J. [BP Oil, Sunbury-on-Thames (United Kingdom)

1999-08-01

323

Characteristics of hydrogen–hydrocarbon composite fuel turbulent jet flames  

Microsoft Academic Search

The characteristics (flame length, pollutant emission, radiative heat loss fraction, and volumetric soot concentration) of hydrogen–hydrocarbon composite fuel turbulent jet diffusion flames are presented. A correlation of flame length with hydrogen concentration in the fuel mixture is shown. The reactivity of fuel mixture increases with the increase of hydrogen concentration, which ultimately shortens the combustion time, and thereby reduces the

Ahsan R. Choudhuri; S. R. Gollahalli

2003-01-01

324

Woodburning as a source of atmospheric polycyclic aromatic hydrocarbons  

Microsoft Academic Search

Airborne particulate matter containing polycyclic aromatic hydrocarbons derived from burning natural vegetation and paper products in a variety of ways was collected and analyzed by HPLC. Similar profiles of compounds resulted from most of the combustion sources that do not involve fossil fuels and that are likely to contribute to Sydney's atmospheric particulates. In addition, the profiles did not change

Diana J. Freeman; Frank C. R. Cattell

1990-01-01

325

Thermal conversion of hydrocarbons with low energy air preheater  

SciTech Connect

Combustion air, prior to being introduced into the cracking furnace in a hydrocarbon pyrolytic conversion and separation system, is preheated by employing bottom pumparound, top pumparound and/or quench water streams diverting from the primary fractionator externally connected to the pyrolysis reactor in order to optimize the thermal efficiency of the overall process.

Bacsik, G.J.

1982-03-23

326

Thermal conversion of hydrocarbons with low energy air preheater  

Microsoft Academic Search

Combustion air, prior to being introduced into the cracking furnace in a hydrocarbon pyrolytic conversion and separation system, is preheated by employing bottom pumparound, top pumparound and\\/or quench water streams diverting from the primary fractionator externally connected to the pyrolysis reactor in order to optimize the thermal efficiency of the overall process.

Bacsik

1982-01-01

327

Structure-biodegradability relationships of polycyclic aromatic hydrocarbons in soil  

Microsoft Academic Search

The potential of some polycyclic aromatic hydrocarbons (PAH) to be metabolized to mutagenic and\\/or carcinogenic compounds (Cerniglia 1984, Gibson & Subramanian 1984) has caused concern for environmental pollution by this class of residues. In industrialized countries, pollution by PAH is primarily associated with the processing, combustion and disposal of fossil fuels (Bartha & Bossert 1984, Hites& LaFlamme 1977), but low

Ingeborg D. Bossert; Richard Bartha

1986-01-01

328

Estimating heats of formation of hydrocarbon radicals by a combination of semiempirical calculation and family correlation with experimental values  

SciTech Connect

A semiempirical method, the PM3-family-correlation (PM3-FC) method, has been developed to estimate the heats of formation ({Delta}H{sup {degree}}{sub f}) of hydrocarbon free radicals. The PM3-FC method combines semiempirical PM3 calculations and family correlation with experimental data. The {Delta}H{degree}{sub f} values for a test set of 67 hydrocarbon free radicals, including alkyl, cycloalkyl, alken-{alpha}-ly, cycloalken-{alpha}-yl, arylalk-{alpha}-ly, alkyn-{alpha}-yl, and vinyl radicals, were calculated by using the Pm3 method and then correlated systematically with the experimental values from the literature. According to the structural analogy of the radicals and the observed correlation, the 67 radicals in the test set can be separated into five groups. The MP3-calculated and experimental values of the radicals in each group exhibit a very good linear correlation. Using the obtained regression parameters to scale the PM3-calculated {Delta}H{degree}{sub f} values leads to a very significant increase in estimation accuracy. For the test set of radicals, excluding the three cyclic hydrocarbon radicals with three carbon atoms in the ring and the three methyl radicals coordinated with three unsaturated groups, the average absolute deviation and the standard deviation between the PM3-FC estimated and experimental enthalpy values are 0.8 and 1.1 kcal/mol, respectively. The 95% confidence limit of the deviation between the PM3-FC-estimated and experimental values is in the interval of {+-}2.1 kcal/mol. The error analysis of the PM3-FC method was performed on the basis of statistical analysis by comparison with other estimation methods. Hydrocarbon free radicals play an important role in many thermal chemistry processes, including combustion, petroleum and coal coking, coal liquefaction and pyrolysis, oil shale retorting, thermal stability of fuels, and free radical polymerization.

Ma, X.; Schobert, H.H.

2000-02-10

329

Atmospheric Chemistry of Acenaphthalene and Acenaphthylene  

NASA Astrophysics Data System (ADS)

Polycyclic aromatic hydrocarbons (PAHs) are released into the atmosphere as a by-product of combustion processes and have been detected in ambient air at urban locations around the world. In the atmosphere, PAHs containing two and three rings are found predominantly in the gas-phase, whilst those containing six or more rings principally adsorb to particles. PAHs with four or five rings are found in both phases. The gas-phase PAHs can be chemically transformed in the lower troposphere via reaction with hydroxyl (OH) and nitrate (NO3) radicals and ozone. These reactions lead to the formation of a range of oxidation products including phenols, nitro-PAHs and carbonyls, in addition to other pollutants such as ozone and secondary organic aerosol (SOA). Despite their importance, relatively little is known about the atmospheric chemistry of the PAHs, mainly because of the difficulty of working with these compounds and also the variety and complexity of the reaction products formed. Up to now only one kinetic study on the reaction of acenaphthalene and acenaphthylene with OH, NO3 and ozone has been reported in the peer-reviewed literature. In this study, we have determined rate coefficients for the gas-phase reactions of acenaphthalene and acenaphthylene with OH, NO3 and ozone using the relative rate method. The results are compared with previous measurements and used to provide estimates of the tropospheric lifetimes of these compounds. A recently developed denuder-filter sampling technique was used to investigate the gas and particle phase products arising from the photooxidation of the PAHs. Chemical analysis was performed using gas chromatography - mass spectrometry using O-(2,3,4,5,6- pentafluorobenzyl)-hydroxylamine (PFBHA) and pentafluorobenzyl bromide (PFBBr) as derivatizing agents for carbonyls and phenols respectively. The results provide new data on the gas-particle partitioning behavior of the oxidation products and useful information on the products likely to be involved in secondary organic aerosol formation from the PAHs.

Zhou, S.; Wenger, J. C.

2009-04-01

330

Fluidized bed combustion method  

SciTech Connect

A process is described for fluidized bed combustion of particulate combustible material in a furnace comprising feeding the particulate combustible material to the furnace and imparting a turbulent fluidized bed motion to the particulate combustible material within the furnace through the use of a vibrating screen. The screen is connected to means for vibrating the screen as the principal source of energy for imparting the turbulent fluidizing motion to the combustible material. This feeds combustion air to the fluidized bed of combustible material, discharging products of combustion from the furnace, and causing the fluidized bed to move in substantially horizontal direction so that combustible material is conveyed from the location of feed to the furnace through a combustion stage in the furnace to the location of discharge as combustible products.

Love, R.E.

1986-12-16

331

HOMOGENEOUS CATALYSTS FOR THE PARTIAL-OXYGENATION OF SATURATED HYDROCARBONS WITH HYDROGEN PEROXIDE  

EPA Science Inventory

The development of catalysts with the capacity to activate green oxidants, such as hydrogen peroxide and molecular oxygen, can offer an environmentally sound pathway for hydrocarbon oxidation. Furthermore, by including the concepts of green chemistry and pollution prevention one ...

332

Simulation of natural-gas combustion in a blast-furnace tuyere  

Microsoft Academic Search

An effective method of reducing blast-furnace coke consumption is to inject gaseous, liquid, or solid fuel in the blast-furnace tuyeres. It is important ensure the maximum possible fuel combustion in the tuyere, since incomplete combustion of hydrocarbons from the fuel results in their pyrolysis, with the formation of soot, which is entrained wastefully from the furnace with the gas or

T. B. Ibadullaev; V. A. Arutyunov; I. A. Levitskii; V. N. Loginov; I. F. Kurunov; S. A. Feshchenko

2007-01-01

333

Split vapor\\/liquid fuel supply system for internal combustion engines  

Microsoft Academic Search

A split vapor\\/liquid fuel supply system is described for an internal combustion engine having: an intake manifold leading to at least one combustion chamber, a fuel tank holding a liquid hydrocarbon fuel supply, a carburetor connected to the fuel supply for feeding fuel to the engine, air supply means for supplying engine intake air to the carburetor for mixing with

La Pan

1987-01-01

334

Combustion and emissions performance of a hybrid hydrogen–gasoline engine at idle and lean conditions  

Microsoft Academic Search

Due to the narrow flammability of gasoline, pure gasoline-fueled spark-ignited (SI) engines always encounter partial burning or even misfire at lean conditions. Gasoline engines tend to suffer poor combustion and expel large emissions at idle conditions because of the high variation in the intake charge and low combustion temperature. Comparatively, hybrid hydrogen engines (HHE) fueled with the mixtures of hydrocarbon

Changwei Ji; Shuofeng Wang

2010-01-01

335

Polycyclic hydrocarbons and carcinogenesis  

Microsoft Academic Search

Polycyclic aromatic hydrocarbons are widespread environmental contaminants and many are exceptionally potent carcinogens in experimental animals. Exposure to various substances containing mixtures of hydrocarbons is associated with excess cancer incidence in humans. Although initial research on hydrocarbon carcinogenesis dates back to the early 1920's, the last two decades have seen a remarkable increase in our understanding of the molecular mechanisms

1985-01-01

336

Combustion apparatus  

US Patent & Trademark Office Database

A combustion apparatus 2 has a fuel spraying nozzle 12, a feed canal 16 and a return canal 17, both the canals connected to the nozzle, with the former canal 16 feeding a fuel to the nozzle and with the latter canal 17 allowing an unsprayed portion of the fuel to flow back. An electromagnetic pump 18 disposed in the feed canal 16 serves to compress the fuel towards the nozzle 12, and an injector valve 25 is disposed in the return canal 17. A controller 40 regulates the operation of the injector valve 25 in the manner of duty-ratio control so as to adjust the flow rate of the fuel being sprayed out of the nozzle 12.

2005-06-21

337

A laboratory scale supersonic combustive flow system  

SciTech Connect

A laboratory scale supersonic flow system [Combustive Flow System (CFS)] which utilizes the gaseous products of methane-air and/or liquid fuel-air combustion has been assembled to provide a propulsion type exhaust flow field for various applications. Such applications include providing a testbed for the study of planar two-dimensional nozzle flow fields with chemistry, three-dimensional flow field mixing near the exit of rectangular nozzles, benchmarking the predictive capability of various computational fluid dynamic codes, and the development and testing of advanced diagnostic techniques. This paper will provide a detailed description of the flow system and data related to its operation.

Sams, E.C.; Zerkle, D.K.; Fry, H.A.; Wantuck, P.J.

1995-02-01

338

Numerical Simulation of Single Aluminum Particle Combustion (Review)  

Microsoft Academic Search

A two-dimensional, unsteady-state, kinetic-diffusion-vaporization-controlled numerical model for aluminum particle combustion\\u000a is presented. The model solves the conservation equations, while accounting for species generation and destruction with a\\u000a 15-reaction kinetic mechanism. Two of the major phenomena that differentiate aluminum combustion from hydrocarbon-droplet\\u000a combustion, namely, condensation of the aluminum-oxide product and subsequent deposition of part of the condensed oxide onto\\u000a the particle,

M. W. Beckstead; Y. Liang; K. V. Pudduppakkam

2005-01-01

339

Review of criteria for vapor-phase hydrocarbons. Final report  

SciTech Connect

Information on vapor-phase hydrocarbons presented in this document covers basic atmospheric chemistry relative to secondary products, especially ozone; sources and emissions; ambient air concentrations; relationship of precursor hydrocarbons to resultant ozone levels in ambient air; health effects; and welfare effects. The principal conclusions from this document are as follows. Hydrocarbons are a principal contributor to the formation of ozone and other photochemical oxidants; however, no fixed single quantitative relationship between precursor hydrocarbons and resulting ozone concentrations can be defined. This relationship varies from site to site depending on local precursor mixes, transport considerations, and meteorological factors. Consequently no single quantitative relationship can be defined nationwide. While specific hydrocarbon compounds can be of concern to public health and welfare, as a class this group of materials cannot be considered a hazard to human health or welfare at or even well above those concentrations observed in the ambient air.

Tilton, B.E.; Bruce, R.M.

1981-10-01

340

Liquid fuel combustion apparatus  

Microsoft Academic Search

A liquid fuel combustion apparatus is described comprising: wall means defining a cylindrical combustion chamber; a cylindrical portion of the wall means having a first port therein for receiving an ignition device and a first nipple integral with the wall means and surrounding the first port; means for introducing fuel and combustion air into the combustion chamber and for removing

K. Sawada; K. Kikuchi

1987-01-01

341

Thermal Pulse Combustion  

Microsoft Academic Search

This paper describes theoretical and experimental observations of combustion oscillations produced in a continuously mixed, jet-stirred combustion system. This work is distinct from other investigations of pulse combustion, because it is shown both theoretically and experimentally that combustion oscillations can be produced with a steady supply of fuel and air, requiring no mechanical or aerodynamic valves. The theory is a

G. A. RICHARDS; G. J. MORRIS; D. W. SHAW; S. A. KEELEY; M. J. WELTER

1993-01-01

342

Rotary internal combustion engine  

SciTech Connect

This patent describes an internal combustion engine comprising; a rotary compressor mechanism; a rotary expander mechanism; and combustion chamber means disposed between the compressor mechanism and the expander mechanism, whereby compressed air is delivered to the combustion chamber through the compressor discharge port, and pressurized gas is delivered from the combustion chamber into the expander mechanism through the pressurized gas intake port.

Le, L.K.

1990-11-20

343

Pulse combustion apparatus  

Microsoft Academic Search

A pulse combustion apparatus is described which includes: a combustion chamber; an exhaust system including an exhaust pipe forming a resonant system with the combustion chamber and a generally cylindrical exhaust cushion chamber downstream of the exhaust pipe for receiving combustion gases from the pipe and communicating with an exhaust outlet form the apparatus; means for delivering successive fuel charges

Kitchen

1986-01-01

344

Laboratory Studies of Hydrocarbon Oxidation Mechanisms  

NASA Astrophysics Data System (ADS)

The oxidation of hydrocarbon species (alkanes, alkenes, halogenated species, and oxygenates of both natural and anthropogenic origin) in the troposphere leads to the generation of numerous potentially harmful secondary pollutants, such as ozone, organic nitrates and acids, and aerosols. These oxidations proceed via the formation of alkoxy radicals, whose complex chemistry controls the ultimate product distributions obtained. Studies of hydrocarbon oxidation mechanisms are ongoing at NCAR and Ford, using environmental chamber / FTIR absorption systems. The focus of these studies is often on the product distributions obtained at low temperature; these studies not only provide data of direct relevance to the free/upper troposphere, but also allow for a more fundamental understanding of the alkoxy radical chemistry (eg., from the determination of the Arrhenius parameters for unimolecular processes, and the quantification of the extent of the involvement of chemical activation in the alkoxy radical chemistry). In this paper, data will be presented on some or all of the following topics: kinetics/mechanisms for the reactions of OH with the unsaturated species MPAN, acrolein, and crotonaldehyde; the mechanism for the oxidation of ethyl chloride and ethyl bromide; and the mechanism for the reaction of OH with acetone and acetaldehyde at low temperature. The relevance of the data to various aspects of tropospheric chemistry will be discussed.

Orlando, J. J.; Tyndall, G. S.; Wallington, T. J.; Burkholder, J. B.; Bertman, S. B.; Chen, W.

2001-12-01

345

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...

346

A Sequential Fluid-mechanic Chemical-kinetic Model of Propane HCCI Combustion  

SciTech Connect

We have developed a methodology for predicting combustion and emissions in a Homogeneous Charge Compression Ignition (HCCI) Engine. This methodology combines a detailed fluid mechanics code with a detailed chemical kinetics code. Instead of directly linking the two codes, which would require an extremely long computational time, the methodology consists of first running the fluid mechanics code to obtain temperature profiles as a function of time. These temperature profiles are then used as input to a multi-zone chemical kinetics code. The advantage of this procedure is that a small number of zones (10) is enough to obtain accurate results. This procedure achieves the benefits of linking the fluid mechanics and the chemical kinetics codes with a great reduction in the computational effort, to a level that can be handled with current computers. The success of this procedure is in large part a consequence of the fact that for much of the compression stroke the chemistry is inactive and thus has little influence on fluid mechanics and heat transfer. Then, when chemistry is active, combustion is rather sudden, leaving little time for interaction between chemistry and fluid mixing and heat transfer. This sequential methodology has been capable of explaining the main characteristics of HCCI combustion that have been observed in experiments. In this paper, we use our model to explore an HCCI engine running on propane. The paper compares experimental and numerical pressure traces, heat release rates, and hydrocarbon and carbon monoxide emissions. The results show an excellent agreement, even in parameters that are difficult to predict, such as chemical heat release rates. Carbon monoxide emissions are reasonably well predicted, even though it is intrinsically difficult to make good predictions of CO emissions in HCCI engines. The paper includes a sensitivity study on the effect of the heat transfer correlation on the results of the analysis. Importantly, the paper also shows a numerical study on how parameters such as swirl rate, crevices and ceramic walls could help in reducing HC and CO emissions from HCCI engines.

Aceves, S M; Flowers, D L; Martinez-Frias, J; Smith, J R; Westbrook, C; Pitz, W; Dibble, R; Wright, J F; Akinyemi, W C; Hessel, R P

2000-11-29

347

Catalytic Chemistry.  

ERIC Educational Resources Information Center

Describes an approach for making chemistry relevant to everyday life. Involves the study of kinetics using the decomposition of hydrogen peroxide by vegetable juices. Allows students to design and carry out experiments and then draw conclusions from their results. (JRH)

Borer, Londa; And Others

1996-01-01

348

Chemistry Notes.  

ERIC Educational Resources Information Center

Describes equipment, activities, and experiments useful in chemistry instruction, including among others, a rapid method to determine available chlorine in bleach, simple flame testing apparatus, and a simple apparatus demonstrating the technique of flash photolysis. (SK)

School Science Review, 1980

1980-01-01

349

Catalytic Chemistry.  

ERIC Educational Resources Information Center

|Describes an approach for making chemistry relevant to everyday life. Involves the study of kinetics using the decomposition of hydrogen peroxide by vegetable juices. Allows students to design and carry out experiments and then draw conclusions from their results. (JRH)|

Borer, Londa; And Others

1996-01-01

350

Nuclear Chemistry.  

ERIC Educational Resources Information Center

Provides a brief review of the latest developments in nuclear chemistry. Nuclear research today is directed toward increased activity in radiopharmaceuticals and formation of new isotopes by high-energy, heavy-ion collisions. (Author/BB)

Chemical and Engineering News, 1979

1979-01-01

351

Green Chemistry  

NSDL National Science Digital Library

Learn about a study in which participants discovered contaminants in their homes, and how green chemistry may provide alternatives to such everyday toxins, in this video adapted from Contaminated Without Consent.

Foundation, Wgbh E.

2011-03-21

352

Chemistry Notes.  

ERIC Educational Resources Information Center

|Describes 13 activities, experiments and demonstrations, including the preparation of iron (III) chloride, simple alpha-helix model, investigating camping gas, redox reactions of some organic compounds, a liquid crystal thermometer, and the oxidation number concept in organic chemistry. (JN)|

School Science Review, 1981

1981-01-01

353

Nuclear Chemistry.  

ERIC Educational Resources Information Center

|Provides a brief review of the latest developments in nuclear chemistry. Nuclear research today is directed toward increased activity in radiopharmaceuticals and formation of new isotopes by high-energy, heavy-ion collisions. (Author/BB)|

Chemical and Engineering News, 1979

1979-01-01

354

Chemistry Notes  

ERIC Educational Resources Information Center

|Several ideas are proposed for chemistry teachers to try in their classrooms. Subjects included are polymerization of acrylate, polymerization of styrene, conductivity, pollution, preparation of chlorine, redox equations, chemiluminescence, and molecular sieves. (PS)|

School Science Review, 1973

1973-01-01

355

Chemistry Notes.  

ERIC Educational Resources Information Center

|Describes equipment, activities, and experiments useful in chemistry instruction, including among others, a rapid method to determine available chlorine in bleach, simple flame testing apparatus, and a simple apparatus demonstrating the technique of flash photolysis. (SK)|

School Science Review, 1980

1980-01-01

356

Organosilicon Chemistry.  

National Technical Information Service (NTIS)

Several new aspects of the chemistry of silylenes, divalent reactive silicon intermediates, have been explored. Insertion reactions of dimethylsilylene into O-H bonds of primary, secondary, and tertiary alcohols were studied. This provides an efficient ro...

W. P. Weber

1982-01-01

357

Clean up hydrocarbon contamination effectively  

SciTech Connect

Hydrocarbon contamination of soil and groundwater is a serious health and environmental issue. Typical contamination sites include manufacturing plants, petroleum refineries, fuel and chemical storage facilities, gasoline service stations, and vehicle depots. Effective remediation of a site contaminated with hydrocarbons requires a sound understanding of regulatory issues, technology options, and the site's hydrogeology. Many treatment options exist, but none is a panacea. The optimal solution for a site is based on a thorough site-specific characterization, followed by a feasibility study that evaluates treatment alternatives. The outcome will be a cost-effective solution that combines treatment alternatives best suited to the site. This article outlines the technologies available for soil and groundwater remediation and how to select an appropriate technology from among them. The paper begins with a discussion on regulatory considerations, dealing with light non-aqueous phase liquids, remediating groundwater, and remediating soils before discussing the following technologies: soil washing, air stripping, carbon adsorption, soil vapor extraction, saturated zone bioremediation, unsaturated zone bioremediation, catalytic combustion, incineration, thermal desorption, in situ chemical oxidation, and UV-enhanced oxidation.

Long, G.M.

1993-05-01

358

Stratospheric chemistry  

SciTech Connect

Advances in stratospheric chemistry made by investigators in the United States from 1987 to 1990 are reviewed. Subject areas under consideration include photochemistry of the polar stratosphere, photochemistry of the global stratosphere, and assessments of inadvertent modification of the stratosphere by anthropogenic activity. Particular attention is given to early observations and theories, gas phase chemistry, Antarctic observations, Arctic observations, odd-oxygen, odd-hydrogen, odd-nitrogen, halogens, aerosols, modeling of stratospheric ozone, and reactive nitrogen effects.

Brune, W.H. (USAF, Geophysics Laboratory, Hanscom AFB, MA (United States))

1991-01-01

359

Chemistry Tutorials  

NSDL National Science Digital Library

The California State University Stanislaus developed these interactive chemistry Web tutorials to assist college students in mass spectrometry, proton NMR chemical shifts, and more. With the many animations and figures, visitors will find assistance with the subtraction and absorption of light and with infrared absorption frequencies for numerous compounds. The titration tutorials simulate laboratory experiments without the hazards of dealing with chemicals. Students will also find a very informative lesson describing how to use Excel to record and analyze their chemistry data.

360

Ethylene oxidation chemistry in a well-stirred reactor  

SciTech Connect

Ethylene is an important intermediate in the combustion of methane, larger aliphatic hydrocarbons, and aromatics. Detailed fuel-lean C{sub 2}H{sub 4}H{sub 2}O/air well-stirred reactor data by Thornton were used to analyze reported combustion chemistry mechanisms and the development of this study`s ethylene oxidation mechanism. The data set had been obtained for the temperature range 1,003 to 1,253 K and ethylene-oxygen equivalence ratio range 0.086 to 0.103, at atmospheric pressure. Mechanisms were derived from reaction sets of Westbrook and Pitz, and Dagaut, Cathonnet and Boettner. Examination of each reported mechanism indicated unusually large kinetic rates for the vinyl decomposition reaction were used in order to obtain agreement with the Thornton data set. An ethylene oxidation model was developed in order to address the mechanistic problems of the previous models. This study`s mechanism well simulated the overall rate of ethylene oxidation and concentration profiles of CO, CO{sub 2}, H{sub 2}, CH{sub 2}O, C{sub 2}H{sub 2}, CH{sub 3}OH, CH{sub 4}, and C{sub 2}H{sub 6}. Successful predictions by the model were dependent on a new high temperature vinyl oxidation reaction route, C{sub 2}H{sub 3} + O{sub 2} = CH{sub 2}CHO + O with a branching ratio of 1.19--1.21 at 1,053 K to 1.63--2.47 at 1,253 K. The branching ratio values were dependent upon the extent of fall-off for the C{sub 2}H{sub 3} + O{sub 2} = CH{sub 2}O + HCO reaction. 132 refs.

Marinov, N. [Lawrence Livermore National Lab., CA (United States); Malte, P. [Univ. of Washington, Seattle, WA (United States). Dept. of Mechanical Engineering

1994-09-01

361

Coal combustion science  

SciTech Connect

The objective of this activity is to support the Office of Fossil Energy in executing research on coal combustion science. This activity consists of basic research on coal combustion that supports both the Pittsburgh Energy Technology Center (PETC) Direct Utilization Advanced Research and Technology Development Program, and the International Energy Agency (IEA) Coal Combustion Science Project. Specific tasks include: coal devolatilization, coal char combustion, and fate of mineral matter during coal combustion. 91 refs., 40 figs., 9 tabs.

Hardesty, D.R. (ed.); Baxter, L.L.; Fletcher, T.H.; Mitchell, R.E.

1990-11-01

362

Fuel Flexibility in Combustion  

SciTech Connect

This poster presents research findings from cofiring studies of various biomass feedstocks such as pentachlorophenol (PCP) and creosote-treated wood, lumber mill and furniture waste sawdusts, pallets, feedlot biomass (cattle manure), hybrid willow, and switchgrass with several bituminous and subbituminous coals. This research includes evaluation of advanced instrumentation and the study of interrelated combustion/emissions issues, such as char burnout, impacts on SO2, NOx, fine particulate (PM2.5), mercury (Hg) and other trace emissions, as well as issues impacting heat transfer, such as ash deposition slagging/fouling behavior. Biomass cofiring in large industrial and utility coal-fired boilers is a practical approach for increasing renewable energy given the wide availability, capital investment, and established performance of coal-fired boilers for providing efficient, low cost power. Although some utility biomass cofiring is successfully practiced in the U.S. and abroad, establishing long-term reliability and improving economics are still significant needs, along with research to support advanced combustion in future Vision 21 systems. Biomass cofiring in Vision 21 systems may reduce fossil CO2 emissions per MWe at capital and operations/maintenance cost savings relative to other technology options. Because an increasing number (currently 14) states have recently passed legislation establishing renewable portfolio standards (RPS), goals, or set-asides that will impact new power generation by 2009 and beyond, cofiring may broaden the appeal of Vision 21 systems to solve other environmental issues, including reducing landfill requirements. Legislation has been proposed to establish a federal RPS as well as extend IRS Section 29/45 tax credits (e.g., $0.005-0.010/kW-hr) for cofiring residues to supplement existing incentives, such as a $0.015/kW-hr tax credit for closed loop biomass (e.g., energy crops, such as switchgrass, hybrid willow) gasification. In addition, the coproduction/cogeneration concepts embodied in Vision 21 may also lend itself well to the type of utility/industry partnering involved in cofiring approaches. In light of the cost limitations in shipping distance (e.g., 50-100 miles or less) from collection to end-use based on the low energy density of biomass, resource availability is a site-specific consideration. Biomass fuels also exhibit significant differences in fuel characteristics, including volatility and ash chemistry that can also influence cofiring performance. Pilot-scale biomass cofiring tests have been conducted in the 150 kWt Combustion and Environmental Research Facility (CERF). A key aspect of the present work is to examine biomass char conversion for a range of initial particle sizes at various residence times for combustion relative to fuel processing/handling issues. In addition, a number of biomass cofiring R&D as well as full-scale utility demonstrations are providing technical insights to assist in cofiring technology commercialization. The paper will also discuss research plans, including lignin cofiring for ethanol/power co-production, novel concepts involving animal waste utilization, advanced combustion studies, and tri-firing concepts with other fuels.

Freeman, M.C.; O'Dowd, W.J.; Mathur, M.P. (U.S. DOE National Energy Technology Laboratory); Walbert, G.F. (Parsons Infrastructure and Technology, Inc.)

2001-11-06

363

Numerical simulations of shock-induced mixing and combustion  

SciTech Connect

In this paper we use numerical simulation to investigate shock-induced ignition and combustion of a hydrocarbon gas. The focus of this paper is on quantifying the effect of fidelity in the chemical kinetics on the overall solution. We model the system using the compressible Navier Stokes equations for a reacting mixture. These equations express conservation of species mass, momentum, total energy.

Bell, John B.; Day, Marc S.; Kuhl, A.

2003-07-27

364

Numerical problems in the solution of oxidation and combustion models  

Microsoft Academic Search

Faced with large and detailed kinetic schemes of pyrolysis, partial oxidation and combustion of hydrocarbon mixtures, the complex process models usually constitute stiff systems of both differential and coupled differential-algebraic equations. This paper discusses different typical applications of a new robust and efficient numerical integration method to solve these problems. The examples refer to gas solid catalytic reactors, partial oxidation

D. Manca; G. Buzzi-Ferraris; T. Faravelli; E. Ranzi

2001-01-01

365

Kinetic models of combustion of kerosene and its components  

Microsoft Academic Search

Modern investigations on creation of kinetic models of combustion of hydrocarbons entering into the composition of kerosene\\u000a and kerosene as a whole have been analyzed. Certain recommendations on application of these models to calculation of actual\\u000a gasdynamic flows have been given.

G. Ya. Gerasimov; S. A. Losev

2005-01-01

366

Combustion Organic Aerosol as Cloud Condensation Nuclei in Ship Tracks  

Microsoft Academic Search

Polycyclic aromatic hydrocarbons (PAHs) have been sampled in marine stratiform clouds to identify the contribution of anthropogenic combustion emissions in activation of aerosol to cloud droplets. The Monterey Area Ship Track experiment provided an opportunity to acquire data on the role of organic compounds in ambient clouds and in ship tracks identified in satellite images. Identification of PAHs in cloud

Lynn M. Russell; Kevin J. Noone; Ronald J. Ferek; Robert A. Pockalny; Richard C. Flagan; John H. Seinfeld

2000-01-01

367

Gasdynamic Model of Turbulent Combustion in TNT Explosions  

Microsoft Academic Search

A model is proposed to simulate turbulent combustion in confined TNT explosions. It is based on: (i) the multi-component gasdynamic conservation laws, (ii) a fast-chemistry model for TNT-air combustion, (iii) a thermodynamic model for frozen reactants and equilibrium products, (iv) a high-order Godunov scheme providing a non-diffusive solution of the governing equations, and (v) an ILES approach whereby adaptive mesh

A L Kuhl; J B Bell; V E Beckner

2010-01-01

368

Gasdynamic model of turbulent combustion in TNT explosions  

Microsoft Academic Search

A model is proposed to simulate turbulent combustion in confined TNT explosions. It is based on: (i) the multi-component gasdynamic conservation laws, (ii) a fast-chemistry model for TNT–air combustion, (iii) a thermodynamic model for frozen reactants and equilibrium products, (iv) a high-order Godunov scheme providing a non-diffusive solution of the governing equations, and (v) an ILES approach whereby adaptive mesh

A. L. Kuhl; J. B. Bell; V. E. Beckner; H. Reichenbach

2011-01-01

369

Nonequilibrium combustion. Final report, 1972--1975  

SciTech Connect

Research conducted under Air Force Office of Scientific Research Grant AFOSR-72-2299 during the period 1972-1975 is summarized and reviewed. The research included (1) flow reactor studies of ammonia oxidation, methylamine pyrolysis, and methylamine oxidation, (2) experimental methods for the study of combustion chemistry, and (3) applications of the research results to problems of aircraft engine pollutant formation and fuels. (Author) (GRA)

Sawyer, R.F.

1976-01-01

370

On mathematical modelling of flameless combustion  

SciTech Connect

A further analysis of the IFRF semi-industrial-scale experiments on flameless (mild) combustion of natural gas is carried out. The experimental burner features a strong oxidizer jet and two weak natural gas jets. Numerous publications have shown the inability of various RANS-based mathematical models to predict the structure of the weak jet. We have proven that the failure is in error predictions of the entrainment and therefore is not related to any chemistry submodels, as has been postulated. (author)

Mancini, Marco; Schwoeppe, Patrick; Weber, Roman [IEVB Institute, Clausthal University of Technology (Germany); Orsino, Stefano [Fluent Inc., Lebanon (United States)

2007-07-15

371

HYDROCARBON OXIDATION OVER VANADIUM PHOSPHORUS OXIDE CATALYST USING HYDROGEN PEROXIDE  

EPA Science Inventory

Selective oxidation of hydrocarbons is one of the very important and challenging areas in industrial chemistry due to the wide ranging utility of the resulting oxygenates in fine chemical synthesis. Most of the existing processes for their oxidations employ toxic and often stoich...

372

Methane conversion to higher hydrocarbons in microwave plasma  

Microsoft Academic Search

Methane conversion to higher hydrocarbons C2 and above was investigated in a microwave plasma reactor The chemistry that needs to be studied in order to understand the conversion process is very similar to the chemical processes that are thought to take place in the stratospheres of reducing planetary atmospheres That is plasma is formed by lightning the plasma is rapidly

T. Kovács; T. Turányi; R. Deam

2006-01-01

373

Combustion 2000  

SciTech Connect

This report presents work carried out under contract DE-AC22-95PC95144 ''Combustion 2000 - Phase II.'' The goals of the program are to develop a coal-fired high performance power generation system (HIPPS) that is capable of: {lg_bullet} thermal efficiency (HHV) {ge} 47% {lg_bullet} NOx, SOx, and particulates {le} 10% NSPS (New Source Performance Standard) {lg_bullet} coal providing {ge} 65% of heat input {lg_bullet} all solid wastes benign {lg_bullet} cost of electricity {le} 90% of present plants Phase I, which began in 1992, focused on the analysis of various configurations of indirectly fired cycles and on technical assessments of alternative plant subsystems and components, including performance requirements, developmental status, design options, complexity and reliability, and capital and operating costs. Phase I also included preliminary R&D and the preparation of designs for HIPPS commercial plants approximately 300 MWe in size. Phase II, had as its initial objective the development of a complete design base for the construction and operation of a HIPPS prototype plant to be constructed in Phase III. As part of a descoping initiative, the Phase III program has been eliminated and work related to the commercial plant design has been ended. The rescoped program retained a program of engineering research and development focusing on high temperature heat exchangers, e.g. HITAF development (Task 2); a rescoped Task 6 that is pertinent to Vision 21 objectives and focuses on advanced cycle analysis and optimization, integration of gas turbines into complex cycles, and repowering designs; and preparation of the Phase II Technical Report (Task 8). This rescoped program deleted all subsystem testing (Tasks 3, 4, and 5) and the development of a site specific engineering design and test plan for the HIPPS prototype plant (Task 7). Work reported herein is from: {lg_bullet} Task 2.2.4 Pilot Scale Testing {lg_bullet} Task 2.2.5.2 Laboratory and Bench Scale Activities

None

2000-06-30

374

Chemical kinetic modelling of hydrocarbon ignition  

SciTech Connect

Chemical kinetic modeling of hydrocarbon ignition is discussed with reference to a range of experimental configurations, including shock tubes, detonations, pulse combustors, static reactors, stirred reactors and internal combustion engines. Important conditions of temperature, pressure or other factors are examined to determine the main chemical reaction sequences responsible for chain branching and ignition, and kinetic factors which can alter the rate of ignition are identified. Hydrocarbon ignition usually involves complex interactions between physical and chemical factors, and it therefore is a suitable and often productive subject for computer simulations. In most of the studies to be discussed below, the focus of the attention is placed on the chemical features of the system. The other physical parts of each application are generally included in the form of initial or boundary conditions to the chemical kinetic parts of the problem, as appropriate for each type of application being addressed.

Westbrook, C.K.; Pitz, W.J.; Curran, H.J.; Gaffuri, P.; Marinov, N.M.

1995-08-25

375

Some chemically improved limestones on the basis of results from thermogravimetry for coal combustion  

SciTech Connect

Work in combustion chemistry by the Division of Energy Demonstrations and Technology, Tennessee Valley Authority (TVA), was implemented in order to achieve some chemically improved limestones having technical and cost-saving advantages for potential utilization by the TVA project for fluidized-bed combustion (FBC). This compilation report describes the results via the following four sections: summary, conclusions, and recommendations; thermogravimetry (TG) for coal combustion and some chemically improved limestones; preparation of chemically improved limestone granules for fluid-bed combustion tests; and evaluation of the sulfur sorption properties of chemically improved limestones during fluidized-bed combustion.

Frazier, G.C.; Hoffmeister, G.; Harrison, C.P.; Grimm, U.; Blouin, G.M.; Lancaster, F.E.

1981-06-01

376

Chemistry Now  

NSDL National Science Digital Library

The National Science Foundation (NSF) recently teamed up with NBC and the National Science Teachers Association to celebrate the International Year of Chemistry. Their big joint project was to create Chemistry Now, a weekly online video series that uncovers and explains the science of common, physical objects. There are over two dozen short films here that cover topics like the chemistry of salt, grapheme, safety glass, and the common cheeseburger. All of the videos are lively and interesting, and they can be used in a wide range of classroom settings to provide visual and audio reinforcement of topics that might be addressed in course lectures and other activities. The videos are completely free and the site includes links to other organizations that have created similar videos.

2012-08-17

377

Aromatic hydrocarbons in New York Bight polychaetes: ultraviolet fluorescence analyses and gas chromatography\\/gas chromatography-mass spectrometry analyses  

Microsoft Academic Search

Polychaetes collected from New York Bight sediments near sewage sludge and harbor dredge spoil drump sites contained a series of diaromatic-tetracyclic hydrocarbons of apparent triterpenoid origin. Microbial processes in sewage sludge are a likely source of these compounds. These octahydrochrysenes were much more abundant in the polychaetes than were the fossil fuel and combustion-derived polycyclic aromatic hydrocarbons which were found

John W. Farrington; Stuart G. Wakeham; Joaquim B. Livramento; Bruce W. Tripp; John M. Teal

1986-01-01

378

Decay of the Singlet Excited States of Nitro-Polycyclic Aromatic Hydrocarbons and its Relevance in the Photochemical Degradation  

Microsoft Academic Search

Nitro-polycyclic aromatic hydrocarbons (NPAHs) are important toxic pollutants formed directly during fuel combustion and indirectly by atmospheric nitration of polyaromatic hydrocarbons. Since photochemical reactions determine the atmospheric ambient stability of these compounds, understanding the dynamics of their singlet excited states is of great importance. Electronically excited NPAHs evolve through two parallel pathways: Intersystem crossing leading to the formation of the

J. Peon

2007-01-01

379

Corrosion performance of materials for advanced combustion systems  

SciTech Connect

Conceptual designs of advanced combustion systems that utilize coal as a feedstock require high-temperature furnaces and heat transfer surfaces capable of operating at much higher temperatures than those in current coal-fired power plants. The combination of elevated temperatures and hostile combustion environments requires development and application of advanced ceramic materials for heat exchangers in these designs. This paper characterizes the chemistry of coal-fired combustion environments over the wide temperature range of interest in these systems and discusses some of the experimental results for several materials obtained from laboratory tests and from exposures in a pilot-scale facility.

Natesan, K. [Argonne National Lab., IL (United States); Freeman, M.; Mathur, M. [Pittsburgh Energy Technology Center, PA (United States)

1995-05-01

380

Combustion 2000  

SciTech Connect

This report presents work carried out under contract DE-AC22-95PC95144 ''Combustion 2000 - Phase II.'' The goals of the program are to develop a coal-fired high performance power generation system (HIPPS) that is capable of: {lg_bullet} thermal efficiency (HHV) {ge} 47% {lg_bullet} NOx, SOx, and particulates {le} 10% NSPS (New Source Performance Standard) {lg_bullet} coal providing {ge} 65% of heat input {lg_bullet} all solid wastes benign {lg_bullet} cost of electricity {le} 90% of present plants Phase I, which began in 1992, focused on the analysis of various configurations of indirectly fired cycles and on technical assessments of alternative plant subsystems and components, including performance requirements, developmental status, design options, complexity and reliability, and capital and operating costs. Phase I also included preliminary R&D and the preparation of designs for HIPPS commercial plants approximately 300 MWe in size. Phase II, had as its initial objective the development of a complete design base for the construction and operation of a HIPPS prototype plant to be constructed in Phase III. As part of a descoping initiative, the Phase III program has been eliminated and work related to the commercial plant design has been ended. The rescoped program retained a program of engineering research and development focusing on high temperature heat exchangers, e.g. HITAF development (Task 2); a rescoped Task 6 that is pertinent to Vision 21 objectives and focuses on advanced cycle analysis and optimization, integration of gas turbines into complex cycles, and repowering designs; and preparation of the Phase II Technical Report (Task 8). This rescoped program deleted all subsystem testing (Tasks 3, 4, and 5) and the development of a site-specific engineering design and test plan for the HIPPS prototype plant (Task 7). Work reported herein is from: {lg_bullet} Task 2.2.4 Pilot Scale Testing {lg_bullet} Task 2.2.5.2 Laboratory and Bench Scale Activities

None

1999-12-31

381

Applications of ultrafast lasers for optical measurements in combusting flows.  

PubMed

Optical measurement techniques are powerful tools for the detailed study of combustion chemistry and physics. Although traditional combustion diagnostics based on continuous-wave and nanosecond-pulsed lasers continue to dominate fundamental combustion studies and applications in reacting flows, revolutionary advances in the science and engineering of ultrafast (picosecond- and femtosecond-pulsed) lasers are driving the enhancement of existing diagnostic techniques and enabling the development of new measurement approaches. The ultrashort pulses afforded by these new laser systems provide unprecedented temporal resolution for studies of chemical kinetics and dynamics, freedom from collisional-quenching effects, and tremendous peak powers for broad spectral coverage and nonlinear signal generation. The high pulse-repetition rates of ultrafast oscillators and amplifiers allow previously unachievable data-acquisition bandwidths for the study of turbulence and combustion instabilities. We review applications of ultrafast lasers for optical measurements in combusting flows and sprays, emphasizing recent achievements and future opportunities. PMID:20636093

Gord, James R; Meyer, Terrence R; Roy, Sukesh

2008-01-01

382

Combustive Sound Source.  

National Technical Information Service (NTIS)

This thesis describes a unique type of low frequency underwater sound source, the Combustive Sound Source (CSS). The fundamental operating principle of CSS is the following: Electrolysis of water produces hydrogen and oxygen gas, which is a combustible mi...

P. S. Wilson

1994-01-01

383

Radiative Augmented Combustion.  

National Technical Information Service (NTIS)

Radiative Augmented Combustion has been identified as a potential technique for extending aircraft operating limits associated with combustion processes. This technique is based on the fact that radiation of selected wavelengths is capable of photodissoci...

M. Lavid

1984-01-01

384

Transient Spray Combustion Computations.  

National Technical Information Service (NTIS)

Many practical combustion devices involves direct injection of liquid fuel into the combustion chamber, e.g., gas turbine engines, diesel engines, rockets and ramjet engines, and furnaces. Typically, the fuel is of sufficiently low volatility that vaporiz...

W. A. Sirignano

1986-01-01

385

Opportunities in Pulse Combustion.  

National Technical Information Service (NTIS)

In pulse combustion, burning occurs in a tube in an oscillatory manner, in contrast to the steady-state combustion used in most boilers and furnaces. With the right combination of the combustor's dimensions, valve characteristics, fuel/oxidizer combinatio...

H. J. Bomelburg D. L. Brenchley

1985-01-01

386

Hydrocarbon emissions speciation in diesel and biodiesel exhausts  

NASA Astrophysics Data System (ADS)

Diesel engine emissions are composed of a long list of organic compounds, ranging from C 2 to C 12+, and coming from the hydrocarbons partially oxidized in combustion or produced by pyrolisis. Many of these are considered as ozone precursors in the atmosphere, since they can interact with nitrogen oxides to produce ozone under atmospheric conditions in the presence of sunlight. In addition to problematic ozone production, Brookes, P., and Duncan, M. [1971. Carcinogenic hydrocarbons and human cells in culture. Nature.] and Heywood, J. [1988. Internal Combustion Engine Fundamentals.Mc Graw-Hill, ISBN 0-07-1000499-8.] determined that the polycyclic aromatic hydrocarbons present in exhaust gases are dangerous to human health, being highly carcinogenic. The aim of this study was to identify by means of gas chromatography the amount of each hydrocarbon species present in the exhaust gases of diesel engines operating with different biodiesel blends. The levels of reactive and non-reactive hydrocarbons present in diesel engine exhaust gases powered by different biodiesel fuel blends were also analyzed. Detailed speciation revealed a drastic change in the nature and quantity of semi-volatile compounds when biodiesel fuels are employed, the most affected being the aromatic compounds. Both aromatic and oxygenated aromatic compounds were found in biodiesel exhaust. Finally, the conservation of species for off-side analysis and the possible influence of engine operating conditions on the chemical characterization of the semi-volatile compound phase are discussed. The use of oxygenated fuel blends shows a reduction in the Engine-Out emissions of total hydrocarbons. But the potential of the hydrocarbon emissions is more dependent on the compositions of these hydrocarbons in the Engine-Out, to the quantity; a large percent of hydrocarbons existing in the exhaust, when biodiesel blends are used, are partially burned hydrocarbons, and are interesting as they have the maximum reactivity, but with the use of pure biodiesel and diesel, the most hydrocarbons are from unburned fuel and they have a less reactivity. The best composition in the fuel, for the control of the hydrocarbon emissions reactivity, needs to be a fuel with high-saturated fatty acid content.

Payri, Francisco; Bermúdez, Vicente R.; Tormos, Bernardo; Linares, Waldemar G.

387

Common Chemistry  

NSDL National Science Digital Library

A web resource that contains Chemical Abstracts Service (CAS) Registry Numbers for approximately 7,800 chemicals of widespread general public interest. Common Chemistry is helpful to non-chemists who know either a name or CAS Registry Number® of a common chemical and want to pair both pieces of information.

Chemical Abstracts Service (CAS)

388

Chemistry Notes  

ERIC Educational Resources Information Center

Short articles on the kinetics of the hydrogen peroxide-iodide ion reaction, simulation of fluidization catalysis, the use of Newman projection diagrams to represent steric relationships in organic chemistry, the use of synthetic substrates for proteolytic enzyme reactions, and two simple clock reactions"--hydrolysis of halogenoalkanes and…

School Science Review, 1972

1972-01-01

389

Chemistry Notes  

ERIC Educational Resources Information Center

|Short articles on the kinetics of the hydrogen peroxide-iodide ion reaction, simulation of fluidization catalysis, the use of Newman projection diagrams to represent steric relationships in organic chemistry, the use of synthetic substrates for proteolytic enzyme reactions, and two simple clock reactions"--hydrolysis of halogenoalkanes and…

School Science Review, 1972

1972-01-01

390

Chemistry Notes.  

ERIC Educational Resources Information Center

|Presents chemistry experiments, laboratory procedures, demonstrations, teaching suggestions, and classroom materials/activities. These include: game for teaching ionic formulas; method for balancing equations; description of useful redox series; computer programs (with listings) for water electrolysis simulation and for determining chemical…

School Science Review, 1983

1983-01-01

391

Chemistry Notes.  

ERIC Educational Resources Information Center

|Presents chemistry experiments, laboratory procedures, demonstrations, and classroom materials/activities. These include: experiments on colloids, processing of uranium ore, action of heat on carbonates; color test for phenols and aromatic amines; solvent properties of non-electrolytes; stereoscopic applications/methods; a valency balance;…

School Science Review, 1983

1983-01-01

392

Green Chemistry  

NSDL National Science Digital Library

This audio segment from PRI's The World Science Podcast explores the science of Green Chemistry. Hear about companies that are developing greener chemicals, and learn why they are fast becoming an attractive alternative for the multi-billion dollar chemical industry.

Foundation, Wgbh E.

2010-02-12

393

Chemistry Notes.  

ERIC Educational Resources Information Center

Presents procedures, experiments, demonstrations, teaching suggestions, and information on a variety of chemistry topics including, for example, inert gases, light-induced reactions, calculators, identification of substituted acetophenones, the elements, analysis of copper minerals, extraction of metallic strontium, equilibrium, halogens, and…

School Science Review, 1982

1982-01-01

394

Confectionary Chemistry.  

ERIC Educational Resources Information Center

|Presents activities and demonstrations that enable teachers to use various types of confections as tactile experiences to spark chemistry students' interest and generate enthusiasm for learning. Presents uses of candy in teaching about atomic structure, spontaneous nuclear decay, chemical formulas, fractoluminescence, the effect of a molecular…

Levine, Elise Hilf

1996-01-01

395

Chemistry Notes.  

ERIC Educational Resources Information Center

|Presents procedures, experiments, demonstrations, teaching suggestions, and information on a variety of chemistry topics including, for example, inert gases, light-induced reactions, calculators, identification of substituted acetophenones, the elements, analysis of copper minerals, extraction of metallic strontium, equilibrium, halogens, and…

School Science Review, 1982

1982-01-01

396

Chemistry's year  

NASA Astrophysics Data System (ADS)

The United Nations has proclaimed 2011 to be the International Year of Chemistry. Under this banner, chemists should seize the opportunity to highlight the rich history and successes of our subject to a much broader audience - and explain how it can help to solve the global challenges we face today and in the future.

2011-01-01

397

Chemistry Notes  

ERIC Educational Resources Information Center

|Describes several chemistry projects, including solubility, formula for magnesium oxide, dissociation of dinitrogen tetroxide, use of 1-chloro-2, 4-dinitrobenzene, migration of ions, heats of neutralizations, use of pocket calculators, sonic cleaning, oxidation states of manganese, and cell potentials. Includes an extract from Chemical Age on…

School Science Review, 1976

1976-01-01

398

Chlorine Chemistry  

NSDL National Science Digital Library

From poolcenter.com comes the Chlorine Chemistry Web site. Ten questions related to chlorine are answered such as What's the History of Chlorine, How Does Chlorine Work to Sanitize, and What Effect Does pH Have on Chlorine. Each is briefly explained in simple and non-technical language.

2008-01-25

399

Chemistry Activities  

NSDL National Science Digital Library

This collection of resource features demonstrations, laboratory investigations, teaching tips, worksheets and other chemistry-related activities. Materials include investigations of mols, nuclear energy, the periodic table, weight and mass, elements, calculations, equations, pH, atomic weight, half-lives, and reactions.

400

Kinetic measurements on elementary fossil fuel combustion reactions over wide temperatures ranges  

Microsoft Academic Search

The goals of this work are to provide accurate data on the temperature dependence of the kinetics of elementary combustion reactions (i) for use by combustion modelers, and (ii) to gain a better fundamental understanding of, and hence predictive ability for, the chemistry involved. Experimental measurements are made using the pseudo-static HTP (high-temperature photochemistry) technique. This approach allows observations on

Fontijin

1992-01-01

401

Modeling the Combustion Behavior of Hazardous Waste in a Rotary Kiln Incinerator  

Microsoft Academic Search

Hazardous wastes have complex physical forms and chemical compositions and are normally incinerated in rotary kilns for safe disposal and energy recovery. In the rotary kiln, the multifeed stream and wide variation of thermal, physical, and chemical properties of the wastes cause the incineration system to be highly heterogeneous, with severe temperature fluctuations and unsteady combustion chemistry. Incomplete combustion is

YONGXIANG YANG; MARC J. A. PIJNENBORG; MARKUS A. REUTER; JOEP VERWOERD

2005-01-01

402

Enhancement of methane combustion in microchannels: Effects of catalyst segmentation and cavities  

Microsoft Academic Search

This paper proposes a novel design concept for the enhancement of methane combustion in a microchannel that uses the combined effects of catalyst segmentation and cavities. The effects and combustion characteristics are evaluated using numerical simulation with detailed heterogeneous and homogeneous chemistries. The effects of a multi-segment catalyst and cavities on channel walls are examined and discussed in terms of

Yueh-Heng Li; Guan-Bang Chen; Hung-Wei Hsu; Yei-Chin Chao

2010-01-01

403

EXPERIMENTAL AND MODELING STUDIES OF STAGED COMBUSTION USING A REACTOR ENGINEERING APPROACH  

Microsoft Academic Search

Combustion research, long dominated by mechanical engineers, is becoming increasingly a chemical engineering application. It is therefore desirable to have a well defined reactor in which to conduct combustion chemistry studies. A two zone laboratory reactor emulating a perfectly stirred reactor + plug flow reactor (PSR + PFR) sequence has been constructed and validated for use in high temperature normal

FUHE MAO; ROBERT B. BARAT

1996-01-01

404

Source fingerprints for volatile non-methane hydrocarbons  

SciTech Connect

Non-methane hydrocarbon (NMHC) source profiles consisting of 35 hydrocarbon species were measured for vehicle and petroleum refinery emissions. Refueling emissions were found to be sensitive to the grade and volatility class of fuel and to be composed mainly of saturated hydrocarbons such as n-butane and 2-methylbutane. Unsaturated and aromatic hydrocarbons, which are released from the tailpipe of vehicles as products of combustion and unburned fuel, were more prevalent in roadway emissions comprising approximately 34 percent of the total NMHCs. Cold-start emissions were nearly indistinguishable from the roadway emission profile. The only significant differences were in toluene, ethylene and acetylene, which may be related to the efficiency of combustion when the vehicle is initially started. Saturated hydrocarbon distributions of the hot-soak profiles were found to be similar to refueling emissions. The only significant difference in the profiles was in the aromatic content, which may be related to the grade of the gasoline and the effectiveness of evaporative emission control devices. The temporal variation in refinery emissions was significant and may be related to variations in refinery activities such as the production and blending of feed stocks to produce different fuels. 21 refs., 1 fig., 6 tabs.

Doskey, P.V. (Argonne National Lab., IL (United States)); Porter, J.A. (Dames and Moore, Park Ridge, IL (United States)); Scheff, P.A. (Univ. of Illinois, Chicago, IL (United States))

1992-11-01

405

Modeling the combustion of JA2 and solid propellants of similar composition  

Microsoft Academic Search

A theoretical study on combustion of JA2, RPD-380, and RPD-351, which are modified double-base propellants composed primarily of three identical nitrate ester ingredients, is presented. A one-dimensional, two-phase model was used [M.S. Miller, W.R. Anderson, in: V. Yang, T.B. Brill, W.Z. Ren (Eds.), Solid Propellant Combustion Chemistry, Combustion and Motor Interior Ballistics, Progress in Astronautics and Aeronautics, vol. 185, AIAA,

Clint B. Conner; William R. Anderson

2009-01-01

406

Vaporized liquid fuel combustion apparatus  

Microsoft Academic Search

This patent describes a vaporized liquid fuel combustion apparatus comprising: a cylinder defining a combustion chamber, the cylinder having an inlet end for receipt of combustion air, a first flange surrounding the inlet end and an outlet end for exhausting gaseous combustion products; means for introducing the fuel into the combustion chamber and ignition means exposed to the combustion chamber

Y. Kimijima; K. Kikuchi

1986-01-01

407

Different fuels combustion burner  

Microsoft Academic Search

This patent describes a burner for simultaneous combustion of liquid and solid fuels comprising: a liquid-fuel combustion nozzle having a liquid fuel injection port for injecting liquid fuel into the burner circumferentially of the liquid fuel nozzle along an arc subtending a predetermined angle; and a solid-fuel combustion nozzle having a solid fuel injection port for injecting a solid fuel

S. Miyamae; T. Abe

1987-01-01

408

Combustion chamber noise suppressor  

Microsoft Academic Search

A combustion chamber is described for a hot fog generating machine comprising a hollow cylindrical combustion chamber shell having a closure plate at one end and outlet means at the opposite end for directing hot combustion gasses to a fogging nozzle, air inlet means disposed adjacent the outlet means, fuel inlet means and ignition means mounted in the closure plate

1986-01-01

409

Combustion synthesis and nanomaterials  

Microsoft Academic Search

The recent developments and trends in combustion science towards the synthesis of nanomaterials are discussed. Different modifications made to conventional combustion approaches for preparation of nanomaterials are critically analyzed. Special attention is paid to various applications of combustion synthesized nanosized products.

Singanahally T. Aruna; Alexander S. Mukasyan

2008-01-01

410

Chemistry Gateways and Resources  

NSDL National Science Digital Library

The Chemistry Gateways and Resources collection is comprised of chemistry-related web portals, web sites, and individual digital resources pertaining to many areas of the discipline - general chemistry, organic and inorganic chemistry, physical chemistry, and others - and intended for a wide range of audiences: educators and learners, the general public, and chemistry research communities.

2008-03-14

411

LABORATORY AND COMPUTATIONAL INVESTIGATIONS OF THE ATMOSPHERIC CHEMISTRY OF KEY OXIDATION PRODUCTS CONTROLLING TROPOSPHERIC OZONE FORMATION  

EPA Science Inventory

Major uncertainties remain in our ability to identify the key reactions and primary oxidation products of volatile hydrocarbons that contribute to ozone formation in the troposphere. To reduce these uncertainties, computational chemistry, mechanistic and process analysis techniqu...

412

Polycyclic antiaromatic hydrocarbons.  

PubMed

Magnetically induced current densities have been calculated for a series of hydrocarbons consisting of hexadehydro[12]annulene rings alternatingly fused with benzenes. The calculations show that all molecular rings of the studied molecules sustain paramagnetic ring currents. The new class of molecules is therefore coined polycyclic antiaromatic hydrocarbons (PAAH). PMID:18989474

Jusélius, Jonas; Sundholm, Dage

2008-09-25

413

Conversion of hydrocarbon oil  

Microsoft Academic Search

A process for producing high antiknock motor fuel, gas and devolatilized coke from hydrocarbon liquids and carbonaceous solids is described. The process comprises charging an enlarged reaction zone with carbonaceous solids, heating a hydrocarbon oil to a relatively high cracking temperature and introducing the oil to the reaction zone passing through the bed of carbonaceous material. Vapors from the reaction

G. Egloff; A. Fisher

1934-01-01

414

Treatment of hydrocarbons  

SciTech Connect

This patent describes a method of treating a caustic-treated hydrocarbon feed mixture having a contaminating concentration of water and sulfur compounds. It includes separating the caustic-treated hydrocarbon feed mixture into a first stream, comprising normal pentane and heavier hydrocarbon compounds and a second stream comprising isopentane and lighter hydrocarbon compounds; contacting the first stream with a molecular sieve material to absorb water and sulfur compounds from the first stream and thereby produce a reactor feed stream having a significant reduction in the concentration of the water and sulfur compounds; isomerizing the reactor feed stream by contacting the reactor feed stream in the presence of hydrogen under suitable isomerization conditions with an isomerization catalyst to produce an isomerate stream comprising isopentane, normal pentane, butane and lighter hydrocarbons, and cyclopentane and heavier hydrocarbons; separating the isomerate stream into at least a third stream comprising cyclopentane and heavier hydrocarbons, a fourth stream comprising butanes and lighter hydrocarbons, a fifth stream comprising normal pentane, and a sixth stream comprising isopentane.

Olbrich, M.E.; Jones, R.L.; Fenstermaker, R.W.

1992-01-21

415

Geology of Hydrocarbons Visualizations  

NSDL National Science Digital Library

This site has over two dozen animations about hydrocarbons as energy sources, including where resources are found, the amount of each energy source/type used in the US and in the world, how hydrocarbons are formed, and how they are found by exploration geologists.

US Geological Survey Western Earth Surface Processes Team; National Park Service.

416

Condensational Growth of Particulate Matter from Partially Premixed Low Temperature Combustion of Biodiesel in a Compression Ignition Engine  

Microsoft Academic Search

Condensational growth is not typically assumed to be significant compared with adsorption for conversion of unburned hydrocarbons in the exhaust of diesel engines to the particulate phase. However, when partially premixed low temperature combustion (LTC) modes designed to simultaneously reduce soot and NOX emissions are implemented, unburned hydrocarbon (UHC) concentrations in the exhaust are an order of magnitude higher than

William F. Northrop; Praveen V. Madathil; Stanislav V. Bohac; Dennis N. Assanis

2011-01-01

417

Nighttime radical observations and chemistry.  

PubMed

The nitrate radical, NO(3), is photochemically unstable but is one of the most chemically important species in the nocturnal atmosphere. It is accompanied by the presence of dinitrogen pentoxide, N(2)O(5), with which it is in rapid thermal equilibrium at lower tropospheric temperatures. These two nitrogen oxides participate in numerous atmospheric chemical systems. NO(3) reactions with VOCs and organic sulphur species are important, or in some cases even dominant, oxidation pathways, impacting the budgets of these species and their degradation products. These oxidative reactions, together with the ozonolysis of alkenes, are also responsible for the nighttime production and cycling of OH and peroxy (HO(2) + RO(2)) radicals. In addition, reactions of NO(3) with biogenic hydrocarbons are particularly efficient and are responsible for the production of organic nitrates and secondary organic aerosol. Heterogeneous chemistry of N(2)O(5) is one of the major processes responsible for the atmospheric removal of nitrogen oxides as well as the cycling of halogen species though the production of nitryl chloride, ClNO(2). The chemistry of NO(3) and N(2)O(5) is also important to the regulation of both tropospheric and stratospheric ozone. Here we review the essential features of this atmospheric chemistry, along with field observations of NO(3), N(2)O(5), nighttime peroxy and OH radicals, and related compounds. This review builds on existing reviews of this chemistry, and encompasses field, laboratory and modelling work spanning more than three decades. PMID:22907130

Brown, Steven S; Stutz, Jochen

2012-08-21

418

Plant hydrocarbon recovery process  

SciTech Connect

A process for production and recovery of hydrocarbons from hydrocarbon-containing whole plants in a form suitable for use as chemical feedstocks or as hydrocarbon energy sources which process comprises: (A) pulverizing by grinding or chopping hydrocarbon-containing whole plants selected from the group consisting of euphorbiaceae, apocynaceae, asclepiadaceae, compositae, cactaceae and pinaceae families to a suitable particle size, (B) drying and preheating said particles in a reducing atmosphere under positive pressure (C) passing said particles through a thermal conversion zone containing a reducing atmosphere and with a residence time of 1 second to about 30 minutes at a temperature within the range of from about 200* C. To about 1000* C., (D) separately recovering the condensable vapors as liquids and the noncondensable gases in a condition suitable for use as chemical feedstocks or as hydrocarbon fuels.

Dzadzic, P.M.; Price, M.C.; Shih, C.J.; Weil, T.A.

1982-01-26

419

In vitro immunotoxic and genotoxic activities of particles emitted from two different small-scale wood combustion appliances  

Microsoft Academic Search

Residential wood combustion appliances emit large quantities of fine particles which are suspected to cause a substantial health burden worldwide. Wood combustion particles contain several potential health-damaging metals and carbon compounds such as polycyclic aromatic hydrocarbons (PAH), which may determine the toxic properties of the emitted particles. The aim of the present study was to characterize in vitro immunotoxicological and

Maija Tapanainen; Pasi I. Jalava; Jorma Mäki-Paakkanen; Pasi Hakulinen; Mikko S. Happo; Heikki Lamberg; Jarno Ruusunen; Jarkko Tissari; Kati Nuutinen; Pasi Yli-Pirilä; Risto Hillamo; Raimo O. Salonen; Jorma Jokiniemi; Maija-Riitta Hirvonen

420

Method of regulating combustion in the combustion chambers of an internal combustion engine  

SciTech Connect

A method is proposed for regulating the combustion of operating mixtures in the combustion chambers of internal combustion engines. The course of the light intensity of the light resulting from combustion in the combustion chamber is detected and evaluated over the course of combustion; reference control variables derived therefrom are formed for use by subsequently disposed closed-loop control devices of the engine.

Burkel, R.; Eckert, K.; Franke, H.; Linder, E.; Maurer, H.; Moser, W.; Muller, K.; Peter, C.; Rieger, F.

1983-05-03

421

A combustion model for IC engine combustion simulations with multi-component fuels  

SciTech Connect

Reduced chemical kinetic mechanisms for the oxidation of representative surrogate components of a typical multi-component automotive fuel have been developed and applied to model internal combustion engines. Starting from an existing reduced mechanism for primary reference fuel (PRF) oxidation, further improvement was made by including additional reactions and by optimizing reaction rate constants of selected reactions. Using a similar approach to that used to develop the reduced PRF mechanism, reduced mechanisms for the oxidation of n-tetradecane, toluene, cyclohexane, dimethyl ether (DME), ethanol, and methyl butanoate (MB) were built and combined with the PRF mechanism to form a multi-surrogate fuel chemistry (MultiChem) mechanism. The final version of the MultiChem mechanism consists of 113 species and 487 reactions. Validation of the present MultiChem mechanism was performed with ignition delay time measurements from shock tube tests and predictions by comprehensive mechanisms available in the literature. A combustion model was developed to simulate engine combustion with multi-component fuels using the present MultiChem mechanism, and the model was applied to simulate HCCI and DI engine combustion. The results show that the present multi-component combustion model gives reliable performance for combustion predictions, as well as computational efficiency improvements through the use of reduced mechanism for multi-dimensional CFD simulations. (author)

Ra, Youngchul; Reitz, Rolf D. [Engine Research Center, University of Wisconsin-Madison (United States)

2011-01-15

422

Surrogate Model Development for Fuels for Advanced Combustion Engines  

SciTech Connect

The fuels used in internal-combustion engines are complex mixtures of a multitude of different types of hydrocarbon species. Attempting numerical simulations of combustion of real fuels with all of the hydrocarbon species included is highly unrealistic. Thus, a surrogate model approach is generally adopted, which involves choosing a few representative hydrocarbon species whose overall behavior mimics the characteristics of the target fuel. The present study proposes surrogate models for the nine fuels for advanced combustion engines (FACE) that have been developed for studying low-emission, high-efficiency advanced diesel engine concepts. The surrogate compositions for the fuels are arrived at by simulating their distillation profiles to within a maximum absolute error of 4% using a discrete multi-component (DMC) fuel model that has been incorporated in the multi-dimensional computational fluid dynamics (CFD) code, KIVA-ERC-CHEMKIN. The simulated surrogate compositions cover the range and measured concentrations of the various hydrocarbon classes present in the fuels. The fidelity of the surrogate fuel models is judged on the basis of matching their specific gravity, lower heating value, hydrogen/carbon (H/C) ratio, cetane number, and cetane index with the measured data for all nine FACE fuels.

Anand, Krishnasamy [University of Wisconsin, Madison; Ra, youngchul [University of Wisconsin, Madison; Reitz, Rolf [University of Wisconsin; Bunting, Bruce G [ORNL

2011-01-01

423

Resin Chemistry  

Microsoft Academic Search

\\u000a During the ensuing years since the last phenolic resins book was published, many new and remarkable developments have occurred\\u000a in the realm of phenolic chemistry and are given in this chapter.\\u000a \\u000a \\u000a A critical examination of the first step or addition step (methylolation) in the preparation of resoles is described and how\\u000a it can be controlled and compared with the typical

Louis Pilato

2010-01-01

424

Theoretical studies on hydrogen ignition and droplet combustion  

Microsoft Academic Search

The objective of this work is to investigate theoretically two different problems of interest in Combustion. First, autoignition in hydrogen-oxygen systems above crossover temperatures and under various conditions of pressure and composition is addressed computationally and by asymptotic methods. Different descriptions of the detailed chemistry are evaluated through comparison of computed and measured ignition times, and a balance between accuracy

Gonzalo Del Alamo

2006-01-01

425

Opportunities in pulse combustion  

SciTech Connect

In most pulse combustors, the combustion occurs near the closed end of a tube where inlet valves operate in phase with the pressure amplitude variations. Thus, within the combustion zone, both the temperature and the pressure oscillate around a mean value. However, the development of practical applications of pulse combustion has been hampered because effective design requires the right combination of the combustor's dimensions, valve characteristics, fuel/oxidizer combination, and flow pattern. Pulse combustion has several additional advantages for energy conversion efficiency, including high combustion and thermal efficiency, high combustion intensity, and high convective heat transfer rates. Also, pulse combustion can be self-aspirating, generating a pressure boost without using a blower. This allows the use of a compact heat exchanger that may include a condensing section and may obviate the need for a chimney. In the last decade, these features have revived interest in pulse combustion research and development, which has resulted in the development of a pulse combustion air heater by Lennox, and a pulse combustion hydronic unit by Hydrotherm, Inc. To appraise this potential for energy savings, a systematic study was conducted of the many past and present attempts to use pulse combustion for practical purposes. The authors recommended areas where pulse combustion technology could possibly be applied in the future and identified areas in which additional R and D would be necessary. Many of the results of the study project derived from a special workshop on pulse combustion. This document highlights the main points of the study report, with particular emphasis on pulse combustion application in chemical engineering.

Brenchley, D.L.; Bomelburg, H.J.

1985-10-01

426

Femtosecond laser induced breakdown for combustion diagnostics  

NASA Astrophysics Data System (ADS)

The focused beam of a 100 fs, 800 nm laser is used to induce a spark in some laminar premixed air-methane flames operating with variable fuel content (equivalence ratio). The analysis of the light escaping from the plasma revealed that the Balmer hydrogen lines, H? and H?, and some molecular origin emissions were the most prominent spectral features, while the CN (?2?+-?2?+) band intensity was found to depend linearly with methane content, suggesting that femtosecond laser induced breakdown spectroscopy can be a useful tool for the in-situ determination and local mapping of fuel content in hydrocarbon-air combustible mixtures.

Kotzagianni, M.; Couris, S.

2012-06-01

427

STRUCTURE-BASED PREDICTIVE MODEL FOR COAL CHAR COMBUSTION  

SciTech Connect

During the past quarter of this project, significant progress continued was made on both major technical tasks. Progress was made at OSU on advancing the application of computational chemistry to oxidative attack on model polyaromatic hydrocarbons (PAHs) and graphitic structures. This work is directed at the application of quantitative ab initio molecular orbital theory to address the decomposition products and mechanisms of coal char reactivity. Previously, it was shown that the ?hybrid? B3LYP method can be used to provide quantitative information concerning the stability of the corresponding radicals that arise by hydrogen atom abstraction from monocyclic aromatic rings. In the most recent quarter, these approaches have been extended to larger carbocyclic ring systems, such as coronene, in order to compare the properties of a large carbonaceous PAH to that of the smaller, monocyclic aromatic systems. It was concluded that, at least for bond dissociation energy considerations, the properties of the large PAHs can be modeled reasonably well by smaller systems. In addition to the preceding work, investigations were initiated on the interaction of selected radicals in the ?radical pool? with the different types of aromatic structures. In particular, the different pathways for addition vs. abstraction to benzene and furan by H and OH radicals were examined. Thus far, the addition channel appears to be significantly favored over abstraction on both kinetic and thermochemical grounds. Experimental work at Brown University in support of the development of predictive structural models of coal char combustion was focused on elucidating the role of coal mineral matter impurities on reactivity. An ?inverse? approach was used where a carbon material was doped with coal mineral matter. The carbon material was derived from a high carbon content fly ash (Fly Ash 23 from the Salem Basin Power Plant. The ash was obtained from Pittsburgh #8 coal (PSOC 1451). Doped samples were then burned in a high temperature flame reactor fitted with rapid quench extractive sampling. It was found that the specific reaction rate decreased with increasing ash content by about an order of magnitude over the ash content range investigated. In this case, it was concluded that at least one of the primary reasons for the resultant observation was that an increasing amount of carbon becomes inaccessible to oxygen by being covered with a fused, ?protective,? ash layer. Progress continued on equipment modification and testing for the combustion experiments with widely varying flame types at OSU.

CHRISTOPHER M. HADAD; JOSEPH M. CALO; ROBERT H. ESSENHIGH; ROBERT H. HURT

1998-06-04

428

Influence of combustion conditions on the PCDD\\/F-, PCB, PCBz- and PAH-concentrations in the post-combustion chamber of a waste incineration pilot plant  

Microsoft Academic Search

Experiments at a pilot scale waste incinerator (0.5 MW thermal power) showed that the conditions in the post-combustion chamber (650–900°C) are strongly influencing the formation of chlorinated and non-chlorinated aromatics. Non-optimal combustion conditions resulted in increased concentrations of mono- to trichlorinated dibenzo-p-dioxins (PCDD), dibenzofurans (PCDF) and polycyclic aromatic hydrocarbons (PAH), while chlorinated benzenes (PCBz), polychlorinated biphenyls (PCB) and the higher

M Blumenstock; R Zimmermann; K.-W Schramm; A Kettrup

2000-01-01

429

A review of the neurotoxicity risk of selected hydrocarbon fuels.  

PubMed

Over 1.3 million civilian and military personnel are occupationally exposed to hydrocarbon fuels, emphasizing gasoline, jet fuel, diesel fuel, or kerosene. These exposures may occur acutely or chronically to raw fuel, vapor, aerosol, or fuel combustion exhaust by dermal, respiratory inhalation, or oral ingestion routes, and commonly occur concurrently with exposure to other chemicals and stressors. Hydrocarbon fuels are complex mixtures of 150-260+ aliphatic and aromatic hydrocarbon compounds containing varying concentrations of potential neurotoxicants including benzene, n-hexane, toluene, xylenes, naphthalene, and certain n-C9-C12 fractions (n-propylbenzene, trimethylbenzene isomers). Due to their natural petroleum base, the chemical composition of different hydrocarbon fuels is not defined, and the fuels are classified according to broad performance criteria such as flash and boiling points, complicating toxicological comparisons. While hydrocarbon fuel exposures occur typically at concentrations below permissible exposure limits for their constituent chemicals, it is unknown whether additive or synergistic interactions may result in unpredicted neurotoxicity. The inclusion of up to six performance additives in existing fuel formulations presents additional neurotoxicity challenge. Additionally, exposures to hydrocarbon fuels, typically with minimal respiratory or dermal protection, range from weekly fueling of personal automobiles to waist-deep immersion of personnel in raw fuel during maintenance of aircraft fuel tanks. Occupational exposures may occur on a near daily basis for from several months to over 20 yr. A number of published studies have reported acute or persisting neurotoxic effects from acute, subchronic, or chronic exposure of humans or animals to hydrocarbon fuels, or to certain constituent chemicals of these fuels. This review summarizes human and animal studies of hydrocarbon fuel-induced neurotoxicity and neurobehavioral consequences. It is hoped that this review will support ongoing attempts to review and possibly revise exposure standards for hydrocarbon fuels. PMID:11503417

Ritchie, G D; Still, K R; Alexander, W K; Nordholm, A F; Wilson, C L; Rossi, J; Mattie, D R

430

Investigation of flow structures in hydrogen-enriched premixed combustion  

NASA Astrophysics Data System (ADS)

Large Eddy Simulation (LES) coupled with Thickened Flame (TF) model has been used to investigate the flow structures in hydrogen-enriched premixed combustion. An unconfined strongly swirled flow, operated at atmospheric condition, is investigated for varying hydrogen percentage as well as swirl strength. Turbulence-chemistry interaction is coupled through LES-TF approach where the flame front is resolved on the computational grid through artificial thickening and the individual species transport equations are directly solved with the reaction rates specified using Arrhenius chemistry. The results show that higher combustibility of hydrogen increases the reaction along the flame front, raises temperature in the reaction zone and thus leads to combustion induced vortex breakdown. In particular, primary interest lies on understanding the flow physics due to hydrogen addition.

De, A.; Acharya, S.

2013-10-01

431

Higher carotinoid petroleum hydrocarbons  

SciTech Connect

Gas chromatography and chromato-mass spectrometry have been used to investigate the saturated hydrocarbon fraction of crude oil from the Sary-Bulak field (Zaisansk basin, Kazakhstan). The high concentration of higher carotinoid cyclanes in the mixture investigated is shown: lexane (C{sub 33}), {gamma}- and {beta}-carotanes (C{sub 40}). The content of the latter hydrocarbon in the saturated fraction reaches 2{center_dot}5%. Ways in which these cyclanes are formed from natural carotinoids are discussed. Mass spectra of the hydrocarbons identified are presented. 8 refs., 4 figs.

Vorob`yeva, N.S.; Zemskova, Z.K.; Punanov, V.G.; Petrov, A.A. [Institute of Geology and Development of Fossil Fuels, Moscow (Russian Federation)

1993-12-31

432

Plasma Processing Of Hydrocarbon  

SciTech Connect

The Idaho National Laboratory (INL) developed several patented plasma technologies for hydrocarbon processing. The INL patents include nonthermal and thermal plasma technologies for direct natural gas to liquid conversion, upgrading low value heavy oil to synthetic light crude, and to convert refinery bottom heavy streams directly to transportation fuel products. Proof of concepts has been demonstrated with bench scale plasma processes and systems to convert heavy and light hydrocarbons to higher market value products. This paper provides an overview of three selected INL patented plasma technologies for hydrocarbon conversion or upgrade.

Grandy, Jon D; Peter C. Kong; Brent A. Detering; Larry D. Zuck

2007-05-01

433

Modeling heterogeneous and homogeneous reactions in the high-temperature catalytic combustion of methane  

Microsoft Academic Search

A high-temperature, short-contact-time catalytic methane combustor is modeled as a plug-flow tubular reactor including both homogeneous and heterogeneous chemistry. The gas-phase chemistry is modeled with GRI-mech 2.11 and the heterogeneous chemistry is modeled using an elementary 19-step mechanism for combustion of methane on platinum. Calculations are made at a variety of pressures, temperatures, compositions, and catalyst pore sizes to determine

C. T Goralski; L. D Schmidt

1999-01-01

434

Biosurfactant production by a soil Pseudomonas strain growing on polycyclic aromatic hydrocarbons  

SciTech Connect

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants occurring mostly as a result of fossil fuel combustion and as by-products of industrial activities. The bioremediation of soils contaminated with PAHs is limited by the poor availability of dyrophobic contaminants to microorganisms. Surfactants can help. Recent studies indicate that addition of surfactants can enhance hydrocarbon biodegradation. This study examines whether production of surfactants by PAH-metabolizing microorganisms is part of their strategy for growing on such poorly available substrates.

Deziel, E.; Paquette, G.; Villemur, R.; Lepine, F. [Univ. du Quebec, Laval (Canada)] [and others

1996-06-01

435

Experimental study of hydrocarbon emissions from closed vessel explosions  

Microsoft Academic Search

Two combustion bombs are used to determine the exhaust hydrocarbon emission after laminar flame propagation through the reactors. Propane and air are used as fuel and oxidizer, and gas chromatography is used to analyze the emission gases. Data are taken over an initial pressure range from 50 kPa to 400 kPa and from an equivalence ratio of 0.7 to the

A. A. Adamczyk; E. W. Kaiser; J. A. Cavolowsky; G. A. Lavoie

1981-01-01

436

Improving Dryer and Press Efficiencies Through Combustion of Hydrocarbon Emissions  

SciTech Connect

Emission control devices on dryers and presses have been legislated into the industry, and are now an integral part of the drying system. These devices consume large quantities of natural gas and electricity and down-sizing or eliminating them will provide major energy savings. The principal strategy taken here focuses on developing process changes that should minimize (and in some cases eliminate) the need for controls. A second approach is to develop lower-cost control options. It has been shown in laboratory and full-scale work that Hazardous Air Pollutants (HAPs) emerge mainly at the end of the press cycle for particleboard, and, by extension, to other prod-ucts. Hence, only the air associated with this point of the cycle need be captured and treated. A model for estimating terpene emissions in the various zones of veneer dryers has been developed. This should allow the emissions to be concentrated in some zones and minimized in others, so that some of the air could be directly released without controls. Low-cost catalysts have been developed for controlling HAPs from dryers and presses. Catalysts conventionally used for regenerative catalytic oxidizers can be used at much lower temperatures for treating press emissions. Fluidized wood ash is an especially inexpensive mate-rial for efficiently reducing formaldehyde in dryer emissions. A heat transfer model for estimating pinene emissions from hot-pressing strand for the manufacture of flakeboard has been constructed from first principles and validated. The model shows that most of the emissions originate from the 1-mm layer of wood adjoining the platen surface. Hence, a simple control option is to surface a softwood mat with a layer of hardwood prior to pressing. Fines release a disproportionate large quantity of HAPs, and it has been shown both theo-retically and in full-scale work that particles smaller than 400 ���µm are principally responsible. Georgia-Pacific is considering green-screening their furnish at several of their mills in order to remove these particles and reduce their treatment costs.

Sujit Banerjee

2005-10-31

437

Ignition and Combustion Properties of Activated Carbon Containing Adsorbed Hydrocarbons.  

National Technical Information Service (NTIS)

Activated carbon contained in large filter beds is used in nuclear submarines for removal of odors and trace contaminants. Because organic vapors are concentrated in this way in the carbon, a study was made to get information for assessing the fire hazard...

F. J. Woods J. E. Johnson

1964-01-01

438

Boiler using combustible fluid  

DOEpatents

A fluid fuel boiler is described comprising a combustion chamber, a cover on the combustion chamber having an opening for introducing a combustion-supporting gaseous fluid through said openings, means to impart rotation to the gaseous fluid about an axis of the combustion chamber, a burner for introducing a fluid fuel into the chamber mixed with the gaseous fluid for combustion thereof, the cover having a generally frustro-conical configuration diverging from the opening toward the interior of the chamber at an angle of between 15/sup 0/ and 55/sup 0/; means defining said combustion chamber having means defining a plurality of axial hot gas flow paths from a downstream portion of the combustion chamber to flow hot gases into an upstream portion of the combustion chamber, and means for diverting some of the hot gas flow along paths in a direction circumferentially of the combustion chamber, with the latter paths being immersed in the water flow path thereby to improve heat transfer and terminating in a gas outlet, the combustion chamber comprising at least one modular element, joined axially to the frustro-conical cover and coaxial therewith. The modular element comprises an inner ring and means of defining the circumferential, radial, and spiral flow paths of the hot gases.

Baumgartner, H.; Meier, J.G.

1974-07-03

439

Chemistry-climate interactions in the Goddard Institute for Space Studies general circulation model, 1, Tropospheric chemistry model description and evaluation  

Microsoft Academic Search

A tropospheric chemistry model has been developed within the Goddard Institute for Space Studies general circulation model (GCM) to study interactions between chemistry and climate change. The model uses simplified chemistry based on CO-NOx-HOx-Ox-CH4 and also includes a parameterization for isoprene emissions, the most important non-methane hydrocarbon. The model reproduces observed annual cycles and mean distributions of key trace gases

Drew T. Shindell; J. Lee Grenfell; David Rind; Volker Grewe; Colin Price

2001-01-01

440

THE ADVANCED CHEMISTRY BASINS PROJECT  

SciTech Connect

In the next decades, oil exploration by majors and independents will increasingly be in remote, inaccessible areas, or in areas where there has been extensive shallow exploration but deeper exploration potential may remain; areas where the collection of data is expensive, difficult, or even impossible, and where the most efficient use of existing data can drive the economics of the target. The ability to read hydrocarbon chemistry in terms of subsurface migration processes by relating it to the evolution of the basin and fluid migration is perhaps the single technological capability that could most improve our ability to explore effectively because it would allow us to use a vast store of existing or easily collected chemical data to determine the major migration pathways in a basin and to determine if there is deep exploration potential. To this end a the DOE funded a joint effort between California Institute of Technology, Cornell University, and GeoGroup Inc. to assemble a representative set of maturity and maturation kinetic models and develop an advanced basin model able to predict the chemistry of hydrocarbons in a basin from this input data. The four year project is now completed and has produced set of public domain maturity indicator and maturation kinetic data set, an oil chemistry and flash calculation tool operable under Excel, and a user friendly, graphically intuitive basin model that uses this data and flash tool, operates on a PC, and simulates hydrocarbon generation and migration and the chemical changes that can occur during migration (such as phase separation and gas washing). The DOE Advanced Chemistry Basin Model includes a number of new methods that represent advances over current technology. The model is built around the concept of handling arbitrarily detailed chemical composition of fluids in a robust finite-element 2-D grid. There are three themes on which the model focuses: chemical kinetic and equilibrium reaction parameters, chemical phase equilibrium, and physical flow through porous media. The chemical kinetic scheme includes thermal indicators including vitrinite, sterane ratios, hopane ratios, and diamonoids; and a user-modifiable reaction network for primary and secondary maturation. Also provided is a database of type-specific kerogen maturation schemes. The phase equilibrium scheme includes modules for primary and secondary migration, multi-phase equilibrium (flash) calculations, and viscosity predictions.

William Goddard; Peter Meulbroek; Yongchun Tang; Lawrence Cathles III

2004-04-05

441

Hydrocarbon emissions from a single-cylinder, divided-chamber diesel engine  

Microsoft Academic Search

The potential sources of hydrocarbon (HC) emissions from a single-cylinder, divided-chamber diesel engine were investigated in this study. To evaluate the relative importance of these sources, the variations of HC emissions with engine speed, air-fuel ratio, combustion timing, intake-air temperature, coolant temperature and oil temperature were examined. Included in the diagnostics of this investigation were: ignition-delay measurements, combustion-chamber surface temperature

Alkidas

1984-01-01

442

Hot gas ignition temperatures of hydrocarbon fuel vapor-air mixtures  

Microsoft Academic Search

Laminar hot air jets of ¹\\/â to ³\\/â-inch diameter were employed to determine the hot gas ignition temperatures of various combustible vapor-air mixtures. The combustibles were n-hexane, n-octane, n-decane, a hydrocarbon jet fuel (JP-6) and an adipate ester aircraft engine oil (MIL-L-7808). Minimum ignition temperatures occurred at a fuel-air weight ratio of about 0.5 and were not greatly sensitive to

R. J. Cato; J. M. Kuchta

1965-01-01

443

Liquid hydrocarbon-fueled thermo-electric generator with counter-flow type regenerative heat exchanger  

Microsoft Academic Search

An air-to-air heat exchanger, comprising an array of stainless steel tubings arranged in a three-fold pass, is connected to the outlet of the combustion chamber of a liquid hydrocarbon-fueled, thermoelectric generator. Air enters the heat exchanger at the ambient temperature and is pre-heated up to 500°C at the same time, the temperature of the gases leaving the combustion chamber is

G. Guazzoni; A. Herchakowski

1980-01-01

444

Mutagenicity of particulates from the laboratory combustion of plastics.  

PubMed

Carcinogenic polycyclic aromatic hydrocarbons (PAHs) and nitropolycyclic aromatic hydrocarbons (nitro-PAHs) have been identified in airborne particulate organic matter extracts. The pollutant sources were generally contributed by motor vehicles and industrial activity. Massive quantities of urban solid wastes, containing plastic materials such as PVC, PET, PS, and PE, burnt in the open air in local garbage dumps are frequently found in developing countries. In this study, the smog particulates from the combustion of these synthetic polymers were produced in a laboratory combustion chamber. The mutagenicity of acetone extracts from the smog particulates was evaluated with Salmonella typhimurium TA98 and TA100 in the presence and absence of S9 mix. Four samples in TA98 exhibited higher mutagenicity than those in TA100. The greatest mutagenicity was observed from the extracts of particulates from combustion of PVC followed by that of PS, PET, and PE. To determine the major mutagenic compounds in these samples, mutagens were partially purified through TLC and their mutagenicity was monitored with TA98. 1-NP and DNPs in the above samples were also determined by HPLC. The amounts of 1-NP and DNPs generally corresponded with their mutagenicity. Higher levels of 1-NP and DNPs were generated from the combustion of PVC, PET, and PS. The combustion of synthetic polymer wastes might be responsible for the presence of high levels of 1-NP and DNPs in Taiwan urban air. PMID:7700277

Lee, H; Wang, L; Shih, J F

1995-03-01

445

Electronic spectroscopy of transient species in solid neon: the indene-motif polycyclic hydrocarbon cation family C9Hy(+) (y = 7-9) and their neutrals.  

PubMed

In this Perspective the development and application of a mass-selective matrix isolation approach, employed with success over the last two decades in the spectroscopic characterization of numerous ions and neutral reactive species, is illustrated with original data for hydrocarbon cations and neutrals with a six- and a five-membered carbon ring fused. The setup allows for the electronic and vibrational assessment of these isolated molecules and ions in the inert neon environment. The transient species of interest are chosen due to their astrophysical relevance, and the role they play in flames, plasmas, combustion, organic reactions and atmospheric chemistry. Electronic absorption and fluorescence spectra of indene-related polycyclic aromatic hydrocarbon derivatives, C9Hy(+) (y = 7-9) cations, are presented. The ions were produced in a discharge source and investigated by means of absorption and emission spectroscopies after selectively trapping them in 6 K neon matrices. Photoconversion between the two C9H8(+) indenylium isomers and, upon irradiation, H2 loss from C9H9(+) were observed. Corresponding neutral species C9Hy are identified by photobleaching the matrices containing the cations. PMID:24108101

Nagy, Adam; Garkusha, Iryna; Fulara, Jan; Maier, John P

2013-10-23

446

Hydrocarbons Via Photosynthesis.  

National Technical Information Service (NTIS)

Photosynthesis, both natural and as a model process, is examined as a possible annually renewable resource for both material and energy. The conversion of carbohydrate from cane and other sources through fermentation alcohol to hydrocarbon may again becom...

M. Calvin

1976-01-01

447

Hydrocarbon - Air Fuel Cells.  

National Technical Information Service (NTIS)

Detailed information is presented on a continuing research and development program to develop a direct hydrocarbon oxidation-air fuel cell technology. Current work included research on electrochemical oxidation processes, electrocatalysts, electrolytes, e...

J. W. Harrison

1965-01-01

448

Geochemistry of cage hydrocarbons  

Microsoft Academic Search

Publications concerning the current status of understanding of the origin of cage hydrocarbons (adamantanes and diamantanes)\\u000a occurring in crude oils are surveyed. The aspects of their use in petroleum geochemistry are discussed.

G. N. Gordadze

2008-01-01

449

(Pesticide chemistry)  

SciTech Connect

This report summarizes a trip by L. W. Barnthouse of the Environmental Sciences Division (ESD), Oak Ridge National Laboratory (ORNL), to Hamburg, Federal Republic of Germany (FRG), where he participated in the 7th International Congress of Pesticide Chemistry. He chaired a workshop on experimental systems for determining effects of pesticides on nontarget organisms and gave an oral presentation at a symposium on pesticide risk assessment. Before returning to the United States, Dr. Barnthouse visited the Netherlands Institute for Sea Research in Texel, the Netherlands.

Barnthouse, L.W.

1990-09-04

450

The relationship between hydrocarbon and stratabound metal sulfide deposits: The Upper Smackover as an analog  

SciTech Connect

A genetic link between hydrocarbon and stratabound metal sulfide deposits has often been suggested. Both are thought to result from similar processes operating during the evolution of sedimentary basins, yet exploitable hydrocarbon and metal sulfide deposits are not found together. Consequently, the nature of their genetic relationship remains unclear. The Upper Jurassic Smackover Formation of the North Louisiana Salt Basin - a prolific hydrocarbon producer - contains disseminated authigenic sulfide minerals reminiscent of stratabound metal sulfide deposits. The close association of these sulfide minerals with hydrocarbon deposits provides an opportunity to examine the relation between the two. The mineralogy and chemistry of late-stage authigenic phases in the Upper Smackover are similar to ore and 'gangue' minerals of Mississippi Valley-type sulfide deposits. The sulfide minerals consist of replacement or pore-filling sphalerite, galena, pyrite, marcasite, and chalcopyrite. The mineralogy and chemistry of the sulfides and their related minerals vary spatially throughout the basin. These variations reflect local processes and the sources of the sulfide minerals' constituents. The same source rocks from which hydrocarbons are derived are likely sources of base metal ions. Likewise, reduced sulfur is related to hydrocarbons by either a common source or by thermochemical sulfate reduction. Thus, spatial variations in chemistry and mineralogy of the late-stage authigenic sulfides of the Upper Smackover may be the key to understanding the relationship between hydrocarbons and stratabound metal sulfide deposits.

Denham, M.E. (Texas A and M Univ., College Station (United States))

1991-03-01

451

Development of an aeroderivative gas turbine DLE combustion system  

SciTech Connect

GE embarked on the detailed design of a new gas-fired, premixed combustion system for its family of aeroderivative gas turbines. This new lean premixed system, sometimes referred to as a dry low-NO[sub x], or a dry low-emissions combustion system, will reduce the emissions of NO[sub x] to less than 25 ppm. The emissions of other pollutants, such as CO, unburned hydrocarbons (UHC), and particulates are also expected to be extremely low. The effects of engine operating conditions and combustor film cooling on emissions and lean flame stability were also studied in some detail. 4 figs.

Leonard, G.; Stegmaier, J. (GE Aircraft Engine Business, Cincinnati, OH (United States))

1993-05-01