Science.gov

Sample records for hydrocarbon combustion chemistry

  1. Combustion chemistry

    SciTech Connect

    Brown, N.J.

    1993-12-01

    This research is concerned with the development and use of sensitivity analysis tools to probe the response of dependent variables to model input variables. Sensitivity analysis is important at all levels of combustion modeling. This group`s research continues to be focused on elucidating the interrelationship between features in the underlying potential energy surface (obtained from ab initio quantum chemistry calculations) and their responses in the quantum dynamics, e.g., reactive transition probabilities, cross sections, and thermal rate coefficients. The goals of this research are: (i) to provide feedback information to quantum chemists in their potential surface refinement efforts, and (ii) to gain a better understanding of how various regions in the potential influence the dynamics. These investigations are carried out with the methodology of quantum functional sensitivity analysis (QFSA).

  2. Combustion of viscous hydrocarbons

    SciTech Connect

    Hayes, M.E.; Hrebenar, K.R.; Murphy, P.L.; Futch, L.E. Jr.; Deal, J.F. III; Bolden, P.L. Jr.

    1987-08-04

    A method is described for utilizing viscous hydrocarbons as combustible pre-atomized fuels, comprising: (A) forming a hydrocarbon-in-water emulsion using an effective amount of a surfactant package comprising at least one water-soluble surfactant, the hydrocarbon-in-water emulsion (1) comprising a hydrocarbon characterized by API gravity of about 20/sup 0/ API or less, viscosity of about 1000 centipoise or greater at 212/sup 0/F., a paraffin content of about 50% by weight or less and, an aromatic content of about 15% by weight or greater, and (2) having a hydrocarbon water ratio from about 60:40 to about 90:10 by volume; and (B) burning the resultant hydrocarbon-in-water emulsion.

  3. Hydrocarbon Fouling of SCR during PCCI combustion

    SciTech Connect

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

    2012-01-01

    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.

  4. Hydrocarbon radical thermochemistry: Gas-phase ion chemistry techniques

    SciTech Connect

    Ervin, Kent M.

    2014-03-21

    Final Scientific/Technical Report for the project "Hydrocarbon Radical Thermochemistry: Gas-Phase Ion Chemistry Techniques." The objective of this project is to exploit gas-phase ion chemistry techniques for determination of thermochemical values for neutral hydrocarbon radicals of importance in combustion kinetics.

  5. LOX/Hydrocarbon Combustion Instability Investigation

    NASA Technical Reports Server (NTRS)

    Jensen, R. J.; Dodson, H. C.; Claflin, S. E.

    1989-01-01

    The LOX/Hydrocarbon Combustion Instability Investigation Program was structured to determine if the use of light hydrocarbon combustion fuels with liquid oxygen (LOX) produces combustion performance and stability behavior similar to the LOX/hydrogen propellant combination. In particular methane was investigated to determine if that fuel can be rated for combustion instability using the same techniques as previously used for LOX/hydrogen. These techniques included fuel temperature ramping and stability bomb tests. The hot fire program probed the combustion behavior of methane from ambient to subambient temperatures. Very interesting results were obtained from this program that have potential importance to future LOX/methane development programs. A very thorough and carefully reasoned documentation of the experimental data obtained is contained. The hot fire test logic and the associated tests are discussed. Subscale performance and stability rating testing was accomplished using 40,000 lb. thrust class hardware. Stability rating tests used both bombs and fuel temperature ramping techniques. The test program was successful in generating data for the evaluation of the methane stability characteristics relative to hydrogen and to anchor stability models. Data correlations, performance analysis, stability analyses, and key stability margin enhancement parameters are discussed.

  6. Combustion chemistry of solid propellants

    NASA Technical Reports Server (NTRS)

    Baer, A. D.; Ryan, N. W.

    1974-01-01

    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 composite propellants yielded data which suggested early ammonium perchlorate decomposition and reaction. The results of a study of the spatial distribution of molecular species in flames from uncatalyzed and copper or lead catalyzed double-based propellants support previously published conclusions concerning the site of action of these metal catalysts. A study of the ammonium-perchlorate-polymeric-fuel-binder reaction in thin films, made by use of infrared absorption spectrometry, yielded a characterization of a rapid condensed-phase reaction which is likely important during the ignition transient and the burning process.

  7. Basic Considerations in the Combustion of Hydrocarbon Fuels with Air

    NASA Technical Reports Server (NTRS)

    Barnett, Henry C; Hibbard, Robert R

    1957-01-01

    Basic combustion research is collected, collated, and interpreted as it applies to flight propulsion. The following fundamental processes are treated in separate chapters: atomization and evaporation of liquid fuels, flow and mixing processes in combustion chambers, ignition and flammability of hydrocarbon fuels, laminar flame propagation, turbulent flames, flame stabilization, diffusion flames, oscillations in combustors, and smoke and coke formation in the combustion of hydrocarbon-air mixtures. Theoretical background, basic experimental data, and practical significance to flight propulsion are presented.

  8. Combustion process for synthesis of carbon nanomaterials from liquid hydrocarbon

    SciTech Connect

    Diener, Michael D.; Alford, J. Michael; Nabity, James; Hitch, Bradley D.

    2007-01-02

    The present invention provides a combustion apparatus for the production of carbon nanomaterials including fullerenes and fullerenic soot. Most generally the combustion apparatus comprises one or more inlets for introducing an oxygen-containing gas and a hydrocarbon fuel gas in the combustion system such that a flame can be established from the mixed gases, a droplet delivery apparatus for introducing droplets of a liquid hydrocarbon feedstock into the flame, and a collector apparatus for collecting condensable products containing carbon nanomaterials that are generated in the combustion system. The combustion system optionally has a reaction zone downstream of the flame. If this reaction zone is present the hydrocarbon feedstock can be introduced into the flame, the reaction zone or both.

  9. Polycyclic aromatic hydrocarbons in interstellar chemistry

    SciTech Connect

    Lepp, S.; Dalgarno, A.

    1988-01-01

    Interstellar chemistry modifications resulting form the presence of large molecules such as polycyclic aromatic hydrocarbons (PAHs) are investigated. For abundances of PAH relative to hydrogen of greater than 10 to the -8th, free electrons attach to PAH molecules to yield PAH(-) ions, and qualitative interstellar chemistry changes are shown to result as atomic and molecular ions undergo nondestructive mutual neutralization reactions with these negative ions. An increase in the steady state abundances of carbon-bearing molecules is also noted. For a PAH abundance ratio relative to hydrogen of 10 to the -7th, the equilibrium densities of C3H2 and neutral atomic C are found to be enhanced by two orders of magnitude. 18 references.

  10. Biofuel combustion chemistry: from ethanol to biodiesel.

    PubMed

    Kohse-Höinghaus, Katharina; Osswald, Patrick; Cool, Terrill A; Kasper, Tina; Hansen, Nils; Qi, Fei; Westbrook, Charles K; Westmoreland, Phillip R

    2010-05-10

    Biofuels, such as bio-ethanol, bio-butanol, and biodiesel, are of increasing interest as alternatives to petroleum-based transportation fuels because they offer the long-term promise of fuel-source regenerability and reduced climatic impact. Current discussions emphasize the processes to make such alternative fuels and fuel additives, the compatibility of these substances with current fuel-delivery infrastructure and engine performance, and the competition between biofuel and food production. However, the combustion chemistry of the compounds that constitute typical biofuels, including alcohols, ethers, and esters, has not received similar public attention. Herein we highlight some characteristic aspects of the chemical pathways in the combustion of prototypical representatives of potential biofuels. The discussion focuses on the decomposition and oxidation mechanisms and the formation of undesired, harmful, or toxic emissions, with an emphasis on transportation fuels. New insights into the vastly diverse and complex chemical reaction networks of biofuel combustion are enabled by recent experimental investigations and complementary combustion modeling. Understanding key elements of this chemistry is an important step towards the intelligent selection of next-generation alternative fuels. PMID:20446278

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

    DOE Data Explorer

    The central feature of the Combustion Chemistry project at LLNL is the development, validation, and application of detailed chemical kinetic reaction mechanisms for the combustion of hydrocarbon and other types of chemical fuels. For the past 30 years, LLNL's Chemical Sciences Division has built hydrocarbon mechanisms for fuels from hydrogen and methane through much larger fuels including heptanes and octanes. Other classes of fuels for which models have been developed include flame suppressants such as halons and organophosphates, and air pollutants such as soot and oxides of nitrogen and sulfur. 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.

  12. Critical reaction rates in hypersonic combustion chemistry

    SciTech Connect

    Oldenborg, R.C.; Harradine, D.M.; Loge, G.W.; Lyman, J.L.; Schott, G.L.; Winn, K.R.

    1989-01-01

    High Mach number flight requires that the scramjet propulsion system operate at a relatively low static inlet pressure and a high inlet temperature. These two constraints can lead to extremely high temperatures in the combustor, yielding high densities of radical species and correspondingly poor chemical combustion efficiency. As the temperature drops in the nozzle expansion, recombination of these excess radicals can produce more product species, higher heat yield, and potentially more thrust. The extent to which the chemical efficiency can be enhanced in the nozzle expansion depends directly on the rate of the radical recombination reactions. A comprehensive assessment of the important chemical processes and an experimental validation of the critical rate parameters is therefore required if accurate predictions of scramjet performance are to be obtained. This report covers the identification of critical reactions, and the critical reaction rates in hypersonic combustion chemistry. 4 refs., 2 figs.

  13. Chemical Kinetics of Hydrocarbon Ignition in Practical Combustion Systems

    SciTech Connect

    Westbrook, C.K.

    2000-07-07

    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.

  14. Multidimensional chemistry coordinate mapping approach for combustion modelling with finite-rate chemistry

    NASA Astrophysics Data System (ADS)

    Jangi, Mehdi; Bai, Xue-Song

    2012-12-01

    A multidimensional chemistry coordinate mapping (CCM) approach is presented for efficient integration of chemical kinetics in numerical simulations of turbulent reactive flows. In CCM the flow transport is integrated in the computational cells in physical space, whereas the integration chemical reactions are carried out in a phase space made up of a few principal variables. Each cell in the phase space corresponds to several computational cells in the physical space, resulting in a speedup of the numerical integration. In reactive flows with small hydrocarbon fuels two principal variables have been shown to be satisfactory to construct the phase space. The two principal variables are the temperature (T) and the specific element mass ratio of the H atom (J H). A third principal variable, σ=∇J H.∇J H, which is related to the dissipation rate of J H, is required to construct the phase space for combustion processes with an initially non-premixed mixture. For complex higher hydrocarbon fuels, e.g. n-heptane, care has to be taken in selecting the phase space in order to model the low-temperature chemistry and ignition process. In this article, a multidimensional CCM algorithm is described for a systematic selection of the principal variables. The method is evaluated by simulating a laminar partially remixed pre-vaporised n-heptane jet ignition process. The CCM approach is then extended to simulate n-heptane spray combustion by coupling the CCM and Reynolds averaged Navier-Stokes (RANS) code. It is shown that the computational time for the integration of chemical reactions can be reduced to only 3-7%, while the result from the CCM method is identical to that of direct integration of the chemistry in the computational cells.

  15. New method for determining heats of combustion of gaseous hydrocarbons

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

    As a spin off of a system developed for monitoring and controlling the oxygen concentration in the Langley 8-foot High Temperature Tunnel, a highly accurate on-line technique was developed for determining heats of combustion of natural gas samples. It is based on measuring the ratio m/n, where m is the (volumetric) flowrate of oxygen required to enrich the carrier air in which the test gas flowing at the rate n is burned, such that the mole fraction of oxygen in the combustion product gases equals that in the carrier air. The m/n ratio is directly related to the heats of combustion of the saturated hydrocarbons present in the natural gas. A measurement of the m/n ratio for the test gas can provide a direct means of determination of its heat of combustion by using the calibration graph relating the m/n values for pure saturated hydrocarbons with their heats of combustion. The accuracy of the technique is determine solely by the accuracy with which the flowrates m and n can be measured and is of the order of 2 percent in the present study. The theoretical principles and experimental results are discussed.

  16. Fundamental and semi-global kinetic mechanisms for hydrocarbon combustion. Final report, March 1977-October 1980

    SciTech Connect

    Dryer, F L; Glassman, I; Brezinsky, K

    1981-03-01

    Over the past three and one half years, substantial research efforts of the Princeton Fuels Research Group have been directed towards the development of simplified mechanisms which would accurately describe the oxidation of hydrocarbons fuels. The objectives of this combustion research included the study of semi-empirical modeling (that is an overall description) of the chemical kinetic mechanisms of simple hydrocarbon fuels. Such fuels include the alkanes: ethane, propane, butane, hexane and octane as well as the critically important alkenes: ethene, propene and butene. As an extension to this work, the study of the detailed radical species characteristics of combustion systems was initiated as another major aspect of the program, with emphasis on the role of the OH and HO/sub 2/ radicals. Finally, the studies of important alternative fuel problems linked the program to longer range approaches to the energy supply question. Studies of alternative fuels composed the major elements of this area of the program. The efforts on methanol research were completed, and while the aromatics aspects of the DOE work have been a direct extension of efforts supported by the Air Force Office of Scientific Research, they represented a significant part of the overall research effort. The emphasis in the proposed program is to provide further fundamental understanding of the oxidation of hydrocarbon fuels which will be useful in guiding engineering approaches. Although the scope of program ranges from the fundamentals of chemical kinetics to that of alternative fuel combustion, the objective in mind is to provide insight and guidance to the understanding of practical combustion environments. The key to our approach has been our understanding of the fundamental combustion chemistry and its relation to the important practical combustion problems which exist in implementing energy efficient, alternate fuels technologies.

  17. Hydrocarbon-fuel/combustion-chamber-liner materials compatibility

    NASA Technical Reports Server (NTRS)

    Gage, Mark L.

    1990-01-01

    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, provided compatibility data in a precisely controlled environment. Dynamic tests, using the Aerojet Carbothermal Test Facility, provided fuel and copper compatibility data under realistic booster engine service conditions. Tests were conducted using very pure grades of each fuel and fuels to which a contaminant, e.g., ethylene or methyl mercaptan, was added to define the role played by fuel impurities. Conclusions are reached as to degradation mechanisms and effects, methods for the elimination of these mechanisms, selection of copper alloy combustion chamber liners, and hydrocarbon fuel purchase specifications.

  18. Relevance and Significance of Extraterrestrial Abiological Hydrocarbon Chemistry.

    PubMed

    Olah, George A; Mathew, Thomas; Prakash, G K Surya

    2016-06-01

    Astrophysical observations show similarity of observed abiological "organics"-i.e., hydrocarbons, their derivatives, and ions (carbocations and carbanions)-with studied terrestrial chemistry. Their formation pathways, their related extraterrestrial hydrocarbon chemistry originating from carbon and other elements after the Big Bang, their parent hydrocarbon and derivative (methane and methanol, respectively), and transportation of derived building blocks of life by meteorites or comets to planet Earth are discussed in this Perspective. Their subsequent evolution on Earth under favorable "Goldilocks" conditions led to more complex molecules and biological systems, and eventually to humans. The relevance and significance of extraterrestrial hydrocarbon chemistry to the limits of science in relation to the physical aspects of evolution on our planet Earth are also discussed. PMID:27045758

  19. The chemistry of hydrocarbon ions in the Jovian ionosphere

    NASA Technical Reports Server (NTRS)

    Kim, Y. H.; Fox, J. L.

    1994-01-01

    We have modeled the chemistry of hydrocarbon ions in the jovian ionosphere. We find that a layer of hydrocarbon ions is formed in the altitude range 300-400 km above the ammonia cloud tops, due largely to direct ionization of hydrocarbons by photons in the wings of the H2 absorption lines in the 912- to 1100-A region that penetrate to below the methane homopause. We have explicitly included in the model 156 ion-neutral reactions involving hydrocaron ions with up to two carbon atoms. Larger hydrocarbon ions are included as two pseudoions, C3Hn(+) and C4Hn(+). The model shows that 15 reactions of H(+), CH3(+), CH5(+), C2H3(+), C2H5(+), and C2H6(+) with hydrocarbon neutrals are the major processes that are responsible for the production and growth of C1-, C2- and C3- or C4-ions in the hydrocarbon ion layer. The model also shows that ions initially produced in the hydrocarbon ion layer are converted into hydrocarbon ions with more than two carbon atoms with very little loss by recombination. It is likely that successive hydrocarbon ion-neutral reactions continue to produce even larger hydrocarbon ions, so the terminal ions probably have more than three or four carbon atoms. In the auroral regions, the chemistry of hydrocarbon ions may modify the densities of neutral hydrocarbons, especially C2H2 in the upper mesosphere, and may play a major role in the production of polar haze particles.

  20. Combustion Chemistry Diagnostics for Cleaner Processes.

    PubMed

    Kohse-Höinghaus, Katharina

    2016-09-12

    Climate change, environmental problems, urban pollution, and the dependence on fossil fuels demand cleaner, renewable energy strategies. However, they also ask for urgent advances in combustion science to reduce emissions. For alternative fuels and new combustion regimes, crucial information about the chemical reactions from fuel to exhaust remains lacking. Understanding such relations between combustion process, fuel, and emissions needs reliable experimental data from a wide range of conditions to provide a firm basis for predictive modeling of practical combustion processes. PMID:27440049

  1. A chemical kinetic modeling study of chlorinated hydrocarbon combustion

    SciTech Connect

    Pitz, W.J.; Westbrook, C.K.

    1990-09-05

    The combustion of chloroethane is modeled as a stirred reactor so that we can study critical emission characteristics of the reactor as a function of residence time. We examine important operating conditions such as pressure, temperature, and equivalence ratio and their influence on destructive efficiency of chloroethane. The model uses a detailed chemical kinetic mechanism that we have developed previously for C{sub 3} hydrocarbons. We have added to this mechanism the chemical kinetic mechanism for C{sub 2} chlorinated hydrocarbons developed by Senkan and coworkers. In the modeling calculations, sensitivity coefficients are determined to find which reaction-rate constants have the largest effect on destructive efficiency. 24 refs., 6 figs., 1 tab.

  2. Explosion-induced combustion of hydrocarbon clouds in a chamber

    SciTech Connect

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

    2001-02-06

    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.

  3. Mach 2 combustion characteristics of hydrogen/hydrocarbon fuel mixtures

    SciTech Connect

    Diskin, G.S.; Jachimowski, C.J.; Northam, G.B.; Bell, R.A.

    1987-01-01

    The combustion of H/sub 2//CH/sub 4/ and H/sub 2//C/sub 2/H/sub 4/ mixtures containing 10 to 70 vol pct hydrocarbon at combustor inlet Mach number 2 and temperatures 2000 to 4000 R is investigated experimentally, applying direct-connect test hardware and techniques similar to those described by Diskin and Northam (1987) in the facilities of the NASA Langley Hypersonic Propulsion Branch. The experimental setup, procedures, and data-reduction methods are described; and the results are presented in extensive tables and graphs and characterized in detail. Fuel type and mixture are found to have little effect on the wall heating rate measured near the combustor exit, but H/sub 2//C/sub 2/H/sub 4/ is shown to burn much more efficiently than H/sub 2//CH/sub 4/, with no pilot-off blowout equivalence ratios greater than 0.5. It is suggested that H/sub 2//hydrocarbon mixtures are feasible fuels (at least in terms of combustion efficiency) for scramjet SSTO vehicles operating at freestream Mach numbers above 4.

  4. A small detailed chemical-kinetic mechanism for hydrocarbon combustion

    SciTech Connect

    Petrova, M.V.; Williams, F.A.

    2006-02-01

    A chemical-kinetic mechanism is presented that is designed to be used for autoignition, deflagrations, detonations, and diffusion flames of a number of different fuels. To keep the mechanism small, attention is restricted to pressures below about 100 atm, temperatures above about 1000 K, and equivalence ratios less than about 3 for the premixed systems, thereby excluding soot formation and low-temperature fuel-peroxide chemistry. Under these restrictions, hydrogen combustion is included with 21 steps among 8 chemical species, combustion of carbon monoxide with 30 steps among 11 species, methane, methanol, ethane, ethylene, and acetylene combustion with 134 steps among 30 species, and propane, propene, allene, and propyne combustion with 177 steps among 37 species. The mechanism has been extensively tested previously for all of these fuels except propane, propene, allene, and propyne. Tests are reported here for these last four fuels through comparisons with experiments and with predictions of other mechanisms for deflagration velocities and shock-tube ignition. (author)

  5. Nanocluster initiation of combustion of off-grade hydrocarbon fuels

    NASA Astrophysics Data System (ADS)

    Alekseenko, S. V.; Pashchenko, S. É.; Salomatov, V. V.

    2010-09-01

    We have performed large-scale experiments on burning, in the regime of nanocluster pulsating combustion, such off-grade fuels as straw oil, hydrocarbon fuel, exhaust crankcase waste, crude oil, and others on the laboratory prototype of the self-contained burner of the Institute of Thermal Physics, Siberian Branch of the Russian Academy of Sciences. The application of modern diagnostics has made it possible to obtain a large body of information on the features of the physicochemical processes of such combustion in the presence of superheated steam. The experimental and theoretical studies have shown that as a result of the heterogeneouscatalytic decomposition of water molecules on soot nanoclusters in the mixing zone, high concentrations of the OH radical are formed and that this decomposition can be effective on carbon particles of size 1-5 nm at temperatures characteristic of traditional flares. The generation of an active OH radical leads to a significant increase in the rates of chemical reactions and a stable high-temperature combustion of "heavy" fuels with the observance of ecological norms.

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

    PubMed Central

    Atkinson, R; Arey, J

    1994-01-01

    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. PMID:7821285

  7. Laser-induced fluorescence measurement of combustion chemistry intermediates

    NASA Technical Reports Server (NTRS)

    Crosley, David R.

    1986-01-01

    Laser-induced fluorescence (LIF) can measure the trace (often free radical) species encountered as intermediates in combustion chemistry; OH, CS, NH, NS, and NCO are typical of the species detected in flames by LIF. Attention is given to illustrative experiments designed to accumulate a quantitative data base for LIF detection in low pressure flow systems and flames, as well as to flame measurements conducted with a view to the detection of new chemical intermediaries that may deepen insight into the chemistry of combustion.

  8. Parallel Performance of a Combustion Chemistry Simulation

    DOE PAGESBeta

    Skinner, Gregg; Eigenmann, Rudolf

    1995-01-01

    We used a description of a combustion simulation's mathematical and computational methods to develop a version for parallel execution. The result was a reasonable performance improvement on small numbers of processors. We applied several important programming techniques, which we describe, in optimizing the application. This work has implications for programming languages, compiler design, and software engineering.

  9. Calorific values and combustion chemistry of animal manure

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Combustion chemistry and calorific value analyses are the fundamental information for evaluating different biomass waste-to-energy conversion operations. Specific chemical exergy of manure and other biomass feedstock will provide a measure for the theoretically maximum attainable energy. The specifi...

  10. Optimization of hydrocarbon fuels combustion variable composition in thermal power plants

    NASA Astrophysics Data System (ADS)

    Saifullin, E. R.; Larionov, V. M.; Busarov, A. V.; Busarov, V. V.

    2016-01-01

    It is known that associated petroleum gas and refinery waste can be used as fuel in thermal power plants. However, random changes in the composition of such fuels cause instability of the combustion process. This article explores the burning of hydrocarbon fuel in the case of long continuous change of its specific heat of combustion. The results of analysis were used to develop a technique of optimizing the combustion process, ensuring complete combustion of the fuel and its minimum flow.

  11. Novel applications of light hydrocarbons chemistry in petroleum exploration

    SciTech Connect

    Mango, F.D. )

    1991-03-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Benezech, Laurent Jean-Michel

    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

  13. RELATIONSHIPS BETWEEN LABORATORY AND PILOT-SCALE COMBUSTION OF SOME CHLORINATED HYDROCARBONS

    EPA Science Inventory

    Factors governing the occurence of trace amounts of residual organic substance emmissions (ROSEs) in full-scale incierators are not fully understood. Pilot-scale spray combustion expereiments involving some liquid chlorinated hydrocarbons (CHCs) and their dilute mixtures with hy...

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

    SciTech Connect

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

    2011-01-01

    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.

  15. Carbon deposition model for oxygen-hydrocarbon combustion, volume 1

    NASA Technical Reports Server (NTRS)

    Hernandez, R.; Ito, J. I.; Niiya, K. Y.

    1987-01-01

    Presented are details of the design, fabrication, and testing of subscale hardware used in the evaluation of carbon deposition characteristics of liquid oxygen and three hydrocarbon fuels for both main chamber and preburner/gas generator operating conditions. In main chamber conditions, the deposition of carbon on the combustion chamber wall was investigated at mixture ratios of 2.0 to 4.0 and at pressures of 1000 to 1500 psia. No carbon deposition on the chamber walls was detected at these main chamber mixture ratios. In preburner/gas generator operating conditions, the deposition of carbon on the turbine simulator tubes was evaluated at mixture ratios of 0.20 to 0.60 and at chamber pressures of 720 to 1650 psia. The results of the tests showed carbon deposition rate to be a strong function of mixture ratio and a weak function of chamber pressure. Further analyses evaluated the operational consequences of carbon deposition on preburner/gas generator performance. The report is in two volumes, of which this is Volume 1 covering the main body of the report plus Appendixes A through D.

  16. Carbon Deposition Model for Oxygen-Hydrocarbon Combustion, Volume 2

    NASA Technical Reports Server (NTRS)

    Hernandez, R.; Ito, J. I.; Niiya, K. Y.

    1987-01-01

    Presented are details of the design, fabrication, and testing of subscale hardware used in the evaluation of carbon deposition characteristics of liquid oxygen and three hydrocarbon fuels for both main chamber and preburner/gas generator operating conditions. In main chamber conditions, the deposition of carbon on the combustion chamber wall was investigated at mixture ratios of 2.0 to 4.0 and at chamber pressures of 1000 to 1500 psia. No carbon deposition on chamber walls was detected at these main chamber mixture ratios. In preburner/gas generator operating conditions, the deposition of carbon on the turbine simulator tubes was evaluated at mixture ratios of 0.20 to 0.60 and at chamber pressures of 720 to 1650 psia. The results of the tests showed carbon deposition rate to be a strong function of mixture ratio and a weak function of chamber pressure. Further analyses evaluated the operational concequences of carbon deposition on preburner/gas generator performance. This is Volume 2 of the report, which contains data plots of all the test programs.

  17. A new comprehensive reaction mechanism for combustion of hydrocarbon fuels

    SciTech Connect

    Ranzi, E.; Sogaro, A.; Gaffuri, P.; Pennati, G.; Westbrook, C.K.; Pitz, W.J.

    1993-12-03

    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.

  18. A filtered tabulated chemistry model for LES of premixed combustion

    SciTech Connect

    Fiorina, B.; Auzillon, P.; Darabiha, N.; Gicquel, O.; Veynante, D.; Vicquelin, R.

    2010-03-15

    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)

  19. Combustion chemistry and an evolving transportation fuel environment.

    SciTech Connect

    Taatjes, Craig A.

    2010-05-01

    The world currently faces tremendous energy challenges stemming from the need to curb potentially catastrophic anthropogenic climate change. In addition, many nations, including the United States, recognize increasing political and economic risks associated with dependence on uncertain and limited energy sources. For these and other reasons the chemical composition of transportation fuels is changing, both through introduction of nontraditional fossil sources, such as oil sands-derived fuels in the US stream, and through broader exploration of biofuels. At the same time the need for clean and efficient combustion is leading engine research towards advanced low-temperature combustion strategies that are increasingly sensitive to this changing fuel chemistry, particularly in the areas of pollutant formation and autoignition. I will highlight the new demands that advanced engine technologies and evolving fuel composition place on investigations of fundamental reaction chemistry. I will focus on recent progress in measuring product formation in elementary reactions by tunable synchrotron photoionization, on the elucidation of pressure-dependent effects in the reactions of alkyl and substituted alkyl radicals with O{sub 2}, and on new combined efforts in fundamental combustion chemistry and engine performance studies of novel potential biofuels.

  20. A simplified reaction mechanism for prediction of NO(x) emissions in the combustion of hydrocarbons

    NASA Technical Reports Server (NTRS)

    Kundu, K. P.; Deur, J. M.

    1992-01-01

    A simplified reaction mechanism is developed for the prediction of NO(x) in hydrocarbon combustion. The mechanism uses fewer reacting species and reaction steps than the detailed mechanisms available in the literature and therefore takes less computer time when used in CFD calculations. The mechanism has been used to calculate NO(x) emissions in the combustion of propane. With slight modifications, the same mechanism can be used to calculate NO(x) in the combustion of other hydrocarbons. Results obtained with the simplified reaction are compared with experimental results and results obtained with a detailed kinetic mechanism.

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

    PubMed

    Comandini, A; Malewicki, T; Brezinsky, K

    2012-03-15

    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

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

    NASA Astrophysics Data System (ADS)

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

    2010-03-01

    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) engine combustion with detailed chemistry (over 500 species) previously using an R-value-based breadth-first search (RBFS) algorithm, which significantly reduced computational times (by as much as 30-fold). The present paper extends the use of this on-the-fly kinetic mechanism reduction scheme to model combustion in direct-injection (DI) engines. It was found that the DAC scheme becomes less efficient when applied to DI engine simulations using a kinetic mechanism of relatively small size and the accuracy of the original DAC scheme decreases for conventional non-premixed combustion engine. The present study also focuses on determination of search-initiating species, involvement of the NOx chemistry, selection of a proper error tolerance, as well as treatment of the interaction of chemical heat release and the fuel spray. Both the DAC schemes were integrated into the ERC KIVA-3v2 code, and simulations were conducted to compare the two schemes. In general, the present DAC scheme has better efficiency and similar accuracy compared to the previous DAC scheme. The efficiency depends on the size of the chemical kinetics mechanism used and the engine operating conditions. For cases using a small n-heptane kinetic mechanism of 34 species, 30% of the computational time is saved, and 50% for a larger n-heptane kinetic mechanism of 61 species. The paper also demonstrates that by combining the present DAC scheme with an adaptive multi-grid chemistry (AMC) solver, it is feasible to simulate a direct-injection engine using a detailed n-heptane mechanism with 543 species

  3. High fidelity chemistry and radiation modeling for oxy -- combustion scenarios

    NASA Astrophysics Data System (ADS)

    Abdul Sater, Hassan A.

    To account for the thermal and chemical effects associated with the high CO2 concentrations in an oxy-combustion atmosphere, several refined gas-phase chemistry and radiative property models have been formulated for laminar to highly turbulent systems. This thesis examines the accuracies of several chemistry and radiative property models employed in computational fluid dynamic (CFD) simulations of laminar to transitional oxy-methane diffusion flames by comparing their predictions against experimental data. Literature review about chemistry and radiation modeling in oxy-combustion atmospheres considered turbulent systems where the predictions are impacted by the interplay and accuracies of the turbulence, radiation and chemistry models. Thus, by considering a laminar system we minimize the impact of turbulence and the uncertainties associated with turbulence models. In the first section of this thesis, an assessment and validation of gray and non-gray formulations of a recently proposed weighted-sum-of-gray gas model in oxy-combustion scenarios was undertaken. Predictions of gas, wall temperatures and flame lengths were in good agreement with experimental measurements. The temperature and flame length predictions were not sensitive to the radiative property model employed. However, there were significant variations between the gray and non-gray model radiant fraction predictions with the variations in general increasing with decrease in Reynolds numbers possibly attributed to shorter flames and steeper temperature gradients. The results of this section confirm that non-gray model predictions of radiative heat fluxes are more accurate than gray model predictions especially at steeper temperature gradients. In the second section, the accuracies of three gas-phase chemistry models were assessed by comparing their predictions against experimental measurements of temperature, species concentrations and flame lengths. The chemistry was modeled employing the Eddy

  4. Computationally efficient implementation of combustion chemistry in parallel PDF calculations

    NASA Astrophysics Data System (ADS)

    Lu, Liuyan; Lantz, Steven R.; Ren, Zhuyin; Pope, Stephen B.

    2009-08-01

    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_mpi, 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

  5. Thermal effect of hydrocarbon fuels combustion after a sudden change in the specific calorific value

    NASA Astrophysics Data System (ADS)

    Saifullin, E. R.; Larionov, V. M.; Busarov, A. V.; Busarov, V. V.

    2016-01-01

    Using associated gas and waste oil refineries in thermal power plants, a complex problem due to the variability in fuel composition. This article explores the burning of hydrocarbon fuel in the case of an abrupt change in its specific combustion heat. Results of the analysis allowed developing a technique of stabilizing the rate of heat release, ensuring complete combustion of the fuel and its minimum flow.

  6. Flame luminosity and unburned hydrocarbon measurements in swirling combustion

    SciTech Connect

    Giovanetti, A.J.; Hoult, D.P.; Keck, J.C.; Sarofim, A.F.

    1980-07-01

    The relationship between flame luminosity and unburned hydrocarbon concentration was studied using an atmospheric, tubular burner. Spectroscopic studies were conducted for different fuels, including kerosene, nitrogen-doped kerosene, and shale oil. Independent exhaust gas analyses were performed on shale oil and nitrogen-doped kerosene. At a particular fuel equivalence ratio, measurements showed flame luminosity to be a function of unburned hydrocarbons. Unburned hydrocarbons were found to become significant prior to an equivalence ratio corresponding to the flame's change from blue to yellow. This critical condition is a function of fuel-air mixing and inlet air preheat temperature. Spectroscopic work revealed presence of strong carbon, hydrocarbon, amine, and cyanide band spectra for the nitrogen-containing fuels. Exhaust gas analyses for shale oil and a comparable nitrogen-doped kerosene were similar.

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

    NASA Astrophysics Data System (ADS)

    Mansurov, Z. A.

    2011-01-01

    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.

  8. A Comparative Study of Eight Finite-Rate Chemistry Kinetics for CO/H-2 Combustion

    SciTech Connect

    Marzouk, OA; ED, Huckaby

    2010-09-01

    We compare the performance and computational cost of 8 kinetic models (3 global and 5 elementary) that describe the finite-rate chemistry of syngas combustion. We apply them in simulating a turbulent jet flame with syngas diluted by 30% nitrogen. We model the turbulence by a modified k-epsilon model and the turbulence-chemistry interaction by the partially stirred reactor approach. To integrate the chemistry equations, we nominally use explicit fifth-order embedded Runge-Kutta ODE solver. But semi-implicit Bulirsch-Stoer and implicit Euler were also used. The computational time depends on the number of reaction steps and the ODE solver. Five models overpredict the maximum flame temperature (by 200 K-320 K). Two models underpredict it by 240 K and 580 K. The global model that is based on the Westbrook-Dryer (1981) model for hydrocarbon fuels gives the best agreement with measurements, and also has low computational demand. Therefore, it is recommended for modeling turbulent syngas flames.

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

    SciTech Connect

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

    2002-05-02

    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.

  10. Rapid computation of chemical equilibrium composition - An application to hydrocarbon combustion

    NASA Technical Reports Server (NTRS)

    Erickson, W. D.; Prabhu, R. K.

    1986-01-01

    A scheme for rapidly computing the chemical equilibrium composition of hydrocarbon combustion products is derived. A set of ten governing equations is reduced to a single equation that is solved by the Newton iteration method. Computation speeds are approximately 80 times faster than the often used free-energy minimization method. The general approach also has application to many other chemical systems.

  11. Isomer-specific combustion chemistry in allene and propyne flames

    SciTech Connect

    Hansen, Nils; Miller, James A.; Westmoreland, Phillip R.; Kasper, Tina; Kohse-Hoeinghaus, Katharina; Wang, Juan; Cool, Terrill A.

    2009-11-15

    A combined experimental and modeling study is performed to clarify the isomer-specific combustion chemistry in flames fueled by the C{sub 3}H{sub 4} isomers allene and propyne. To this end, mole fraction profiles of several flame species in stoichiometric allene (propyne)/O{sub 2}/Ar flames are analyzed by means of a chemical kinetic model. The premixed flames are stabilized on a flat-flame burner under a reduced pressure of 25 Torr (=33.3 mbar). Quantitative species profiles are determined by flame-sampling molecular-beam mass spectrometry, and the isomer-specific flame compositions are unraveled by employing photoionization with tunable vacuum-ultraviolet synchrotron radiation. The temperature profiles are measured by OH laser-induced fluorescence. Experimental and modeled mole fraction profiles of selected flame species are discussed with respect to the isomer-specific combustion chemistry in both flames. The emphasis is put on main reaction pathways of fuel consumption, of allene and propyne isomerization, and of isomer-specific formation of C{sub 6} aromatic species. The present model includes the latest theoretical rate coefficients for reactions on a C{sub 3}H{sub 5} potential [J.A. Miller, J.P. Senosiain, S.J. Klippenstein, Y. Georgievskii, J. Phys. Chem. A 112 (2008) 9429-9438] and for the propargyl recombination reactions [Y. Georgievskii, S.J. Klippenstein, J.A. Miller, Phys. Chem. Chem. Phys. 9 (2007) 4259-4268]. Larger peak mole fractions of propargyl, allyl, and benzene are observed in the allene flame than in the propyne flame. In these flames virtually all of the benzene is formed by the propargyl recombination reaction. (author)

  12. Comprehensive mechanisms for combustion chemistry: Experiment, modeling, and sensitivity analysis

    SciTech Connect

    Dryer, F.L.; Yetter, R.A.

    1993-12-01

    This research program is an integrated experimental/numerical effort to study pyrolysis and oxidation reactions and mechanisms for small-molecule hydrocarbon structures under conditions representative of combustion environments. The experimental aspects of the work are conducted in large diameter flow reactors, at pressures from one to twenty atmospheres, temperatures from 550 K to 1200 K, and with observed reaction times from 10{sup {minus}2} to 5 seconds. Gas sampling of stable reactant, intermediate, and product species concentrations provides not only substantial definition of the phenomenology of reaction mechanisms, but a significantly constrained set of kinetic information with negligible diffusive coupling. Analytical techniques used for detecting hydrocarbons and carbon oxides include gas chromatography (GC), and gas infrared (NDIR) and FTIR methods are utilized for continuous on-line sample detection of light absorption measurements of OH have also been performed in an atmospheric pressure flow reactor (APFR), and a variable pressure flow (VPFR) reactor is presently being instrumented to perform optical measurements of radicals and highly reactive molecular intermediates. The numerical aspects of the work utilize zero and one-dimensional pre-mixed, detailed kinetic studies, including path, elemental gradient sensitivity, and feature sensitivity analyses. The program emphasizes the use of hierarchical mechanistic construction to understand and develop detailed kinetic mechanisms. Numerical studies are utilized for guiding experimental parameter selections, for interpreting observations, for extending the predictive range of mechanism constructs, and to study the effects of diffusive transport coupling on reaction behavior in flames. Modeling using well defined and validated mechanisms for the CO/H{sub 2}/oxidant systems.

  13. Photographic combustion characterization of LOX/Hydrocarbon type propellants

    NASA Technical Reports Server (NTRS)

    Judd, D. C.

    1980-01-01

    One hundred twenty-seven tests were conducted over a chamber pressure range of 125-1500 psia, a fuel temperature range of -245 F to 158 F, and a fuel velocity range of 48-707 ft/sec to demonstrate the advantages and limitations of using high speed photography to identify potential combustion anomalies such as pops, fuel freezing, reactive stream separation and carbon formations. Combustion evaluation criteria were developed to guide selection of the fuels, injector elements, and operating conditions for testing. Separate criteria were developed for fuel and injector element selection and evaluation. The photographic test results indicated conclusively that injector element type and design directly influence carbon formation. Unlike spray fan, impingement elements reduce carbon formation because they induce a relatively rapid near zone fuel vaporization rate. Coherent jet impingement elements, on the other hand, exhibit increased carbon formation.

  14. Photographic Combustion Characterization of LOX/Hydrocarbon Type Propellants

    NASA Technical Reports Server (NTRS)

    Judd, D. C.

    1980-01-01

    The advantages and limitations of using high speed photography to identify potential combustion anomalies (pops, fuel freezing, reactive stream separation (RSS), carbon formation) were demonstrated. Combustion evaluation criteria were developed for evaluating, characterizing, and screening promising low cost propellant combination(s) and injector element(s) for long life, reusable engine systems. Carbon formation and RSS mechanisms and trends were identified by using high speed color photography at speeds up to 6000 frames/sec. Single element injectors were tested with LOX/RP-1, LOX/Propane, LOX/Methane and LOX/Ammonia propellants. Tests were conducted using seven separate injector elements. Five different conventionally machined elements were tested: OFO Triplet; Rectangular Unlike Doublet (RUD); Unlike Doublet (UD); Like on Lke Doublet (LOL-EDM); and Slit Triplet.

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

    PubMed Central

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

    2009-01-01

    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. PMID:19251660

  16. Spray Combustion Modeling with VOF and Finite-Rate Chemistry

    NASA Technical Reports Server (NTRS)

    Chen, Yen-Sen; Shang, Huan-Min; Liaw, Paul; Wang, Ten-See

    1996-01-01

    A spray atomization and combustion model is developed based on the volume-of-fluid (VOF) transport equation with finite-rate chemistry model. The gas-liquid interface mass, momentum and energy conservation laws are modeled by continuum surface force mechanisms. A new solution method is developed such that the present VOF model can be applied for all-speed range flows. The objectives of the present study are: (1) to develop and verify the fractional volume-of-fluid (VOF) cell partitioning approach into a predictor-corrector algorithm to deal with multiphase (gas-liquid) free surface flow problems; (2) to implement the developed unified algorithm in a general purpose computational fluid dynamics (CFD) code, Finite Difference Navier-Stokes (FDNS), with droplet dynamics and finite-rate chemistry models; and (3) to demonstrate the effectiveness of the present approach by simulating benchmark problems of jet breakup/spray atomization and combustion. Modeling multiphase fluid flows poses a significant challenge because a required boundary must be applied to a transient, irregular surface that is discontinuous, and the flow regimes considered can range from incompressible to highspeed compressible flows. The flow-process modeling is further complicated by surface tension, interfacial heat and mass transfer, spray formation and turbulence, and their interactions. The major contribution of the present method is to combine the novel feature of the Volume of Fluid (VOF) method and the Eulerian/Lagrangian method into a unified algorithm for efficient noniterative, time-accurate calculations of multiphase free surface flows valid at all speeds. The proposed method reformulated the VOF equation to strongly couple two distinct phases (liquid and gas), and tracks droplets on a Lagrangian frame when spray model is required, using a unified predictor-corrector technique to account for the non-linear linkages through the convective contributions of VOF. The discontinuities within the

  17. Plasma Assisted Combustion Mechanism for Hydrogen and Small Hydrocarbons

    NASA Astrophysics Data System (ADS)

    Starikovskiy, Andrey; Aleksandrov, Nikolay

    2015-09-01

    The main mechanisms of nonequilibrium gas excitation and their influence on the ignition and combustion were briefly discussed. Rotational excitation, vibrational excitation, electronic excitation, dissociation by electron impact and ionization were all analyzed, as well as the ways in which the selectivity of the gas excitation in the discharge can be controlled. The model consists of two parts. The first part describes gas excitation by electron impact - rotational, vibrational and electronic states population by pulsed discharges. The second part considers energy relaxation in the plasma (formation of Maxwell-Boltzmann equilibrium across translational, vibrational and electronic degrees of freedom of molecules), quenching and decomposition of excited states, their reactions and recombination - with formation of thermally-equilibrium pool of radicals, which could be considered as initial conditions for any detailed combustion kinetic mechanism. The mechanism was verified against available kinetic data in a wide temperature range. Despite of some lack of knowledge of mechanism details, nonequilibrium plasma demonstrates great potential for controlling ultra-lean, ultra-fast, low-temperature flames and is an extremely promising technology for a very wide range of applications.

  18. Photographic combustion characterization of LOX/hydrocarbon type propellants

    NASA Technical Reports Server (NTRS)

    Judd, D. C.

    1979-01-01

    Single element injectors and two fuels were tested with the aim of photographically characterizing observed combustion phenomena. The three injectors tested were the O-F-O triplet, the transverse like on like (TLOL), and the rectangular unlike doublet (RUD). The fuels tested were RP-1 and propane. The hot firings were conducted in a specifically constructed chamber fitted with quartz windows for photographically viewing the impingement spray field. All LOX/HC testing demonstrated coking with the RP-1 fuel leaving far more soot than the propane fuel. No fuel freezing or popping was experienced under the test conditions evaluated. Carbon particle emission and combustion light brilliance increased with Pc for both fuels although RP-1 was far more energetic in this respect. The RSS phenomena appear to be present in the high Pc tests as evidenced by striations in the spray pattern and by separate fuel rich and oxidizer rich areas. The RUD element was also tested as a fuel rich gas generator element by switching the propellant circuits. Excessive sooting occurred at this low mixture ratio (0.55), precluding photographic data.

  19. Investigating an annular nozzle on combustion products of hydrocarbon fuels

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

    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.

  20. Chemistry in the Center for Catalytic Hydrocarbon Functionalization. An Energy Frontier Research Center

    SciTech Connect

    Golisz, Suzanne R.; Gunnoe, T. Brent; Goddard, William A.; Groves, John T.; Periana, Roy A.

    2010-12-02

    Selective catalysts that activate small molecules such as hydrocarbons, dioxygen, water, carbon dioxide and dihydrogen are central to new technologies for the use of alternative energy sources. For example, controlled hydrocarbon functionalization can lead to high impact technologies, but such catalysts require a level of molecular control beyond current means. The Center for Catalytic Hydrocarbon Functionalization facilitates collaborations among research groups in catalysis, materials, electrochemistry, bioinorganic chemistry and quantum mechanics to develop, validate and optimize new methods to rearrange the bonds of hydrocarbons, activate and transform water and carbon dioxide, implement enzymatic strategies into synthetic systems and design optimal environments for catalysis.

  1. Hydrocarbon-fuel/copper combustion chamber liner compatibility, corrosion prevention, and refurbishment

    NASA Technical Reports Server (NTRS)

    Rosenberg, S. D.; Gage, M. L.; Homer, G. D.; Franklin, J. E.

    1991-01-01

    An evaluation is made of combustion product/combustion chamber compatibility in the case of a LOX/liquid hydrocarbon booster engine based on copper-alloy thrust chamber which is regeneratively cooled by the fuel. It is found that sulfur impurities in the fuel are the primary causes of copper corrosion, through formation of Cu2S; sulfur levels as low as 1 ppm can result in sufficiently severe copper corrosion to degrade cooling channel performance. This corrosion can be completely eliminated, however, through the incorporation of an electrodeposited gold coating on the copper cooling-channel walls.

  2. Thermodynamic and transport combustion properties of hydrocarbons with air. Part 4: Compositions corresponding to Rankine temperature schedules in part 3

    NASA Technical Reports Server (NTRS)

    Gordon, S.

    1982-01-01

    The equilibrium compositions corresponding to the thermodynamic and transport combustion properties for a wide range of conditions for the reaction of hydrocarbons with air are presented. The compositions presented correspond to Rankine temperature schedules.

  3. Combustion performance and heat transfer characterization of LOX/hydrocarbon type propellants. Task 3: Data dump

    NASA Technical Reports Server (NTRS)

    Hart, S. W.

    1982-01-01

    A preliminary characterization of Orbital Maneuvering System (OMS) and Reaction Control System (RCS) engine point designs over a range of thrust and chamber pressure for several hydrocarbon fuels is reported. OMS and RCS engine point designs were established in two phases comprising baseline and parametric designs. Interface pressures, performance and operating parameters, combustion chamber cooling and turboprop requirements, component weights and envelopes, and propellant conditioning requirements for liquid to vapor phase engine operation are defined.

  4. Ammonia chemistry in oxy-fuel combustion of methane

    SciTech Connect

    Mendiara, Teresa; Glarborg, Peter

    2009-10-15

    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)

  5. Speciated hydrocarbon emissions from the combustion of single component fuels. 1. Effect of fuel structure

    SciTech Connect

    Siegel, W.O.; McCabe, R.W.; Chun, W.; Kaiser, E.W.; Perry, J.; Henig, Y.I.; Trinker, F.H.; Anderson, R.W. )

    1992-07-01

    Speciated hydrocarbon emissions data have been collected for six single-component fuels run in a laboratory pulse flame combustor (PFC). The six fuels include n-heptane, isoctane (2,2,4-trimethylpentane), cyclohexane, 1-hexene, toluene, and methyl-t-butyl ether. Combustion of non-aromatic fuels in the PFC produced low levels of unburned fuel and high yields of methane and olefins irrespective of the molecular structure of the fuel. In contrast, hydrocarbon emissions from toluene combustion in the PFC were comprised predominantly of unburned fuel. With the PFC, low levels of 1,3-butadiene were observed from all the fuels except MTBE, for which no measurable level was detected; low levels of benzene were observed from isooctane, heptane, and 1-hexene, but significant levels from cyclohexane and toluene. No measurable amount of benzene was observed in the MTBE exhaust. For isooctane and toluene the speciated hydrocarbon emissions from a spark-ignited (SI) single-cylinder engine were also determined. HC emissions from the Si engine contained the same species as observed from the PFC, although the relative composition was different. For the non-aromatic fuel isooctane, unburned fuel represented a larger fraction of the HC emissions when run in the engine. HC emissions from toluene combustion in the engine were smaller to those from the PFC.

  6. Hydrocarbon-fuel/combustion-chamber-liner materials compatibility

    NASA Technical Reports Server (NTRS)

    Homer, G. David

    1991-01-01

    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 Cu2S, 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 Cu2S. 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.

  7. Surface combustion microengines based on photocatalytic oxidations of hydrocarbons at room temperature.

    PubMed

    Su, Ming; Dravid, Vinayak P

    2005-10-01

    The concept of a surface combustion microengine that is fuelled by volatile hydrocarbons at room temperature is demonstrated on a microcantilever covered with a thin layer of titanium oxide (TiO(2)). Exposing this microengine to ultraviolet (UV) radiation and hydrocarbon vapor produces controlled bending of the microcantilever as a result of differential stress produced by photocatalytic oxidation of organic molecules on the TiO(2) coating. Compared to the motion generated solely by UV radiation or hydrocarbon adsorption, the unique photocatalytic-mechanical effects in the presence of UV and hydrocarbon produce more work and exhibit fast response. The surface combustion based microengines would require less maintenance in minimally controlled field environment and could be potentially used in construction of miniature movable machines, conversion of solar and chemical energy to mechanical work, when extended to a large array of microcantilevers. We believe such microengines can be fuelled by a variety of molecules or mixtures due to the generally favorable photocatalytic reactivity of TiO(2), thus potentially offering a broad approach for mechanical work generation from multiple energy sources. PMID:16218731

  8. Characteristics and combustion of future hydrocarbon fuels. [aircraft fuels

    NASA Technical Reports Server (NTRS)

    Rudey, R. A.; Grobman, J. S.

    1978-01-01

    As the world supply of petroleum crude oil is being depleted, the supply of high-quality crude oil is also dwindling. This dwindling supply is beginning to manifest itself in the form of crude oils containing higher percentages of aromatic compounds, sulphur, nitrogen, and trace constituents. The result of this trend is described and the change in important crude oil characteristics, as related to aircraft fuels, is discussed. As available petroleum is further depleted, the use of synthetic crude oils (those derived from coal and oil shale) may be required. The principal properties of these syncrudes and the fuels that can be derived from them are described. In addition to the changes in the supply of crude oil, increasing competition for middle-distillate fuels may require that specifications be broadened in future fuels. The impact that the resultant potential changes in fuel properties may have on combustion and thermal stability characteristics is illustrated and discussed in terms of ignition, soot formation, carbon deposition flame radiation, and emissions.

  9. Assessment of Turbulence-Chemistry Interaction Models in the National Combustion Code (NCC) - Part I

    NASA Technical Reports Server (NTRS)

    Wey, Thomas Changju; Liu, Nan-suey

    2011-01-01

    This paper describes the implementations of the linear-eddy model (LEM) and an Eulerian FDF/PDF model in the National Combustion Code (NCC) for the simulation of turbulent combustion. The impacts of these two models, along with the so called laminar chemistry model, are then illustrated via the preliminary results from two combustion systems: a nine-element gas fueled combustor and a single-element liquid fueled combustor.

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

    SciTech Connect

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

    2012-06-15

    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.

  11. Laser Spectrometric Measurement System for Local Express Diagnostics of Flame at Combustion of Liquid Hydrocarbon Fuels

    NASA Astrophysics Data System (ADS)

    Kobtsev, V. D.; Kozlov, D. N.; Kostritsa, S. A.; Smirnov, V. V.; Stel'makh, O. M.; Tumanov, A. A.

    2016-03-01

    A laboratory laser spectrometric measurement system for investigation of spatial distributions of local temperatures in a flame at combustion of vapors of various liquid hydrocarbon fuels in oxygen or air at atmospheric pressure is presented. The system incorporates a coherent anti-Stokes Raman spectrometer with high spatial resolution for local thermometry of nitrogen-containing gas mixtures in a single laser shot and a continuous operation burner with a laminar diffusion flame. The system test results are presented for measurements of spatial distributions of local temperatures in various flame zones at combustion of vapor—gas n-decane/nitrogen mixtures in air. Its applicability for accomplishing practical tasks in comparative laboratory investigation of characteristics of various fuels and for research on combustion in turbulent flames is discussed.

  12. Problems in Catalytic Oxidation of Hydrocarbons and Detailed Simulation of Combustion Processes

    NASA Astrophysics Data System (ADS)

    Xin, Yuxuan

    This dissertation research consists of two parts, with Part I on the kinetics of catalytic oxidation of hydrocarbons and Part II on aspects on the detailed simulation of combustion processes. In Part I, the catalytic oxidation of C1--C3 hydrocarbons, namely methane, ethane, propane and ethylene, was investigated for lean hydrocarbon-air mixtures over an unsupported Pd-based catalyst, from 600 to 800 K and under atmospheric pressure. In Chapter 2, the experimental facility of wire microcalorimetry and simulation configuration were described in details. In Chapter 3 and 4, the oxidation rate of C1--C 3 hydrocarbons is demonstrated to be determined by the dissociative adsorption of hydrocarbons. A detailed surface kinetics model is proposed with deriving the rate coefficient of hydrocarbon dissociative adsorption from the wire microcalorimetry data. In Part II, four fundamental studies were conducted through detailed combustion simulations. In Chapter 5, self-accelerating hydrogen-air flames are studied via two-dimensional detailed numerical simulation (DNS). The increase in the global flame velocity is shown to be caused by the increase of flame surface area, and the fractal structure of the flame front is demonstrated by the box-counting method. In Chapter 6, skeletal reaction models for butane combustion are derived by using directed relation graph (DRG) and DRG-aided sensitivity analysis (DRGASA), and uncertainty minimization by polynomial chaos expansion (MUM-PCE) mothodes. The dependence of model uncertainty is subjected to the completeness of the model. In Chapter 7, a systematic strategy is proposed to reduce the cost of the multicomponent diffusion model by accurately accounting for the species whose diffusivity is important to the global responses of the combustion systems, and approximating those of less importance by the mixture-averaged model. The reduced model is validated in an n-heptane mechanism with 88 species. In Chapter 8, the influence of Soret

  13. Intermediates in the Formation of Aromatics in Hydrocarbon Combustion

    NASA Technical Reports Server (NTRS)

    Walch, Stephen P.; Langhoff, S. R. (Technical Monitor)

    1994-01-01

    The formation of the first benzene ring is believed to be the rate limiting step in soot formation. Two different mechanisms have been proposed for formation of cyclic C6 species. The first involves the reaction of two acetylenes to give CH2CHCCH (vinyl acetylene), the loss of a H to give CHCHCCH (n-C41-13) or CH2CCCH (iso-C4H3), and addition of another acetylene to n-C4H3, followed by ring closure to give phenyl radical. Miller and Melius argue that only n-C4H3 leads to phenyl radical and since iso-C4H3 is more stable than n-C4H3 this mechanism is unlikely. An alternative mechanism proposed by them is formation of benzene from the dimerization of two CH2CCH (propargyl) radicals (formed by the reaction of singlet methylene with C2H2). We report reaction pathways and accurate energetics (from CASSCF/internally contracted CI calculations) for the reactions of CH(pi-2) and CH2-1 with acetylene, the reaction of vinylidene with acetylene, and the reaction of n-C4H3 and iso-C4H3 with acetylene. These calculations identify two new reactive intermediates CHCHCH ( a A"-2 ground state in Cs symmetry; spin coupling is a doublet from three singly occupied orbitals) and CHCCH (B-3 ground state in C2 symmetry) from the reaction of CH with acetylene. These species dimerize with no barrier to form benzene and para-benzyne, respectively. CHCCH is proposed as a reactive intermediate which can add to benzene to give higher polynuclear aromatic hydrocarbons or fullerenes. The addition of a C3H2 unit releases two C-C bond energies and thus the resulting addition product contains sufficient energy to break several CH bonds leading to a reduction in the H to C ratio as the cluster size increases. It is found that iso-C4H3 adds to acetylene to initially give a fulvene radical but that this species rearranges to phenyl radical. Thus, the reaction of acetylene with iso-C4H3 does lead to phenyl radical and the cyclization pathway may also contribute to formation of the initial benzene ring.

  14. Combustion

    NASA Technical Reports Server (NTRS)

    Bulzan, Dan

    2007-01-01

    An overview of the emissions related research being conducted as part of the Fundamental Aeronautics Subsonics Fixed Wing Project is presented. The overview includes project metrics, milestones, and descriptions of major research areas. The overview also includes information on some of the emissions research being conducted under NASA Research Announcements. Objective: Development of comprehensive detailed and reduced kinetic mechanisms of jet fuels for chemically-reacting flow modeling. Scientific Challenges: 1) Developing experimental facilities capable of handling higher hydrocarbons and providing benchmark combustion data. 2) Determining and understanding ignition and combustion characteristics, such as laminar flame speeds, extinction stretch rates, and autoignition delays, of jet fuels and hydrocarbons relevant to jet surrogates. 3) Developing comprehensive kinetic models for jet fuels.

  15. Determination of Combustion Product Radicals in a Hydrocarbon Fueled Rocket Exhaust Plume

    NASA Technical Reports Server (NTRS)

    Langford, Lester A.; Allgood, Daniel C.; Junell, Justin C.

    2007-01-01

    The identification of metallic effluent materials in a rocket engine exhaust plume indicates the health of the engine. Since 1989, emission spectroscopy of the plume of the Space Shuttle Main Engine (SSME) has been used for ground testing at NASA's Stennis Space Center (SSC). This technique allows the identification and quantification of alloys from the metallic elements observed in the plume. With the prospect of hydrocarbon-fueled rocket engines, such as Rocket Propellant 1 (RP-1) or methane (CH4) fueled engines being considered for use in future space flight systems, the contributions of intermediate or final combustion products resulting from the hydrocarbon fuels are of great interest. The effect of several diatomic molecular radicals, such as Carbon Dioxide , Carbon Monoxide, Molecular Carbon, Methylene Radical, Cyanide or Cyano Radical, and Nitric Oxide, needs to be identified and the effects of their band systems on the spectral region from 300 nm to 850 nm determined. Hydrocarbon-fueled rocket engines will play a prominent role in future space exploration programs. Although hydrogen fuel provides for higher engine performance, hydrocarbon fuels are denser, safer to handle, and less costly. For hydrocarbon-fueled engines using RP-1 or CH4 , the plume is different from a hydrogen fueled engine due to the presence of several other species, such as CO2, C2, CO, CH, CN, and NO, in the exhaust plume, in addition to the standard H2O and OH. These species occur as intermediate or final combustion products or as a result of mixing of the hot plume with the atmosphere. Exhaust plume emission spectroscopy has emerged as a comprehensive non-intrusive sensing technology which can be applied to a wide variety of engine performance conditions with a high degree of sensitivity and specificity. Stennis Space Center researchers have been in the forefront of advancing experimental techniques and developing theoretical approaches in order to bring this technology to a more

  16. Real-time prediction of hydrocarbon emissions from liquid combustion systems

    SciTech Connect

    Barton, R.G.; Riale, M.; McCampbell, D.; VanDyne, M.

    1997-12-31

    A laboratory study was conducted to investigate the ability of heuristic computational techniques to predict hydrocarbon emissions using data from simple process and optical monitors. A mini-pilot scale combustion research facility located at Midwest Research Institute was used was used in the study. The facility`s operational and emissions characteristics have been well defined in previous studies. The facility was fired with fuel oil and operated at wide range of combustion conditions. All operating parameters including fuel feed rate, air feed rates and chamber temperature were monitored. In addition, a CCD-array video camera was used to monitor the flame. An array of conventional continuous emissions monitors for CO, CO{sub 2}, O{sub 2}, and THC sampled the exhaust gases. The operational data and the optical field data were combined with the emissions data to form a training data set for a neural network. The trained network was then used to predict the THC emissions.

  17. Hydrocarbons. Independent Learning Project for Advanced Chemistry (ILPAC). Unit O1.

    ERIC Educational Resources Information Center

    Inner London Education Authority (England).

    This unit on hydrocarbons is one of 10 first year units produced by the Independent Learning Project for Advanced Chemistry (ILPAC). The unit is divided into sections dealing with alkanes, alkenes, alkynes, arenes, and several aspects of the petroleum industry. Two experiments, exercises (with answers), and pre- and post-tests are included.…

  18. Chemistry and the Internal Combustion Engine II: Pollution Problems.

    ERIC Educational Resources Information Center

    Hunt, C. B.

    1979-01-01

    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)

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

    NASA Astrophysics Data System (ADS)

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

    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.

  20. In situ oxidation of carbon-encapsulated cobalt nanocapsules creates highly active cobalt oxide catalysts for hydrocarbon combustion.

    PubMed

    Wang, Han; Chen, Chunlin; Zhang, Yexin; Peng, Lixia; Ma, Song; Yang, Teng; Guo, Huaihong; Zhang, Zhidong; Su, Dang Sheng; Zhang, Jian

    2015-01-01

    Combustion catalysts have been extensively explored to reduce the emission of hydrocarbons that are capable of triggering photochemical smog and greenhouse effect. Palladium as the most active material is widely applied in exhaust catalytic converter and combustion units, but its high capital cost stimulates the tremendous research on non-noble metal candidates. Here we fabricate highly defective cobalt oxide nanocrystals via a controllable oxidation of carbon-encapsulated cobalt nanoparticles. Strain gradients induced in the nanoconfined carbon shell result in the formation of a large number of active sites featuring a considerable catalytic activity for the combustion of a variety of hydrocarbons (methane, propane and substituted benzenes). For methane combustion, the catalyst displays a unique activity being comparable or even superior to the palladium ones. PMID:26074206

  1. In situ oxidation of carbon-encapsulated cobalt nanocapsules creates highly active cobalt oxide catalysts for hydrocarbon combustion

    NASA Astrophysics Data System (ADS)

    Wang, Han; Chen, Chunlin; Zhang, Yexin; Peng, Lixia; Ma, Song; Yang, Teng; Guo, Huaihong; Zhang, Zhidong; Su, Dang Sheng; Zhang, Jian

    2015-06-01

    Combustion catalysts have been extensively explored to reduce the emission of hydrocarbons that are capable of triggering photochemical smog and greenhouse effect. Palladium as the most active material is widely applied in exhaust catalytic converter and combustion units, but its high capital cost stimulates the tremendous research on non-noble metal candidates. Here we fabricate highly defective cobalt oxide nanocrystals via a controllable oxidation of carbon-encapsulated cobalt nanoparticles. Strain gradients induced in the nanoconfined carbon shell result in the formation of a large number of active sites featuring a considerable catalytic activity for the combustion of a variety of hydrocarbons (methane, propane and substituted benzenes). For methane combustion, the catalyst displays a unique activity being comparable or even superior to the palladium ones.

  2. In situ oxidation of carbon-encapsulated cobalt nanocapsules creates highly active cobalt oxide catalysts for hydrocarbon combustion

    PubMed Central

    Wang, Han; Chen, Chunlin; Zhang, Yexin; Peng, Lixia; Ma, Song; Yang, Teng; Guo, Huaihong; Zhang, Zhidong; Su, Dang Sheng; Zhang, Jian

    2015-01-01

    Combustion catalysts have been extensively explored to reduce the emission of hydrocarbons that are capable of triggering photochemical smog and greenhouse effect. Palladium as the most active material is widely applied in exhaust catalytic converter and combustion units, but its high capital cost stimulates the tremendous research on non-noble metal candidates. Here we fabricate highly defective cobalt oxide nanocrystals via a controllable oxidation of carbon-encapsulated cobalt nanoparticles. Strain gradients induced in the nanoconfined carbon shell result in the formation of a large number of active sites featuring a considerable catalytic activity for the combustion of a variety of hydrocarbons (methane, propane and substituted benzenes). For methane combustion, the catalyst displays a unique activity being comparable or even superior to the palladium ones. PMID:26074206

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

    SciTech Connect

    Taniguchi, Masayuki; Kamikawa, Yuki; Okazaki, Teruyuki; Yamamoto, Kenji; Orita, Hisayuki

    2010-08-15

    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)

  4. 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...

  5. Resonance Energy of an Arene Hydrocarbon from Heat of Combustion Measurements

    PubMed Central

    Kolesnichenko, Vladimir L.

    2015-01-01

    A simple experimental method for determination of the resonance energy by measuring the energies of combustion for two isomeric compounds, aromatic 1-tert-butyl-3,5-dimethylbenzene and nonaromatic trans,trans,cis-1,5,9-cyclododecatriene is proposed. Both compounds not only have the same molecular formula, but also contain the same number of sp2 and sp3 carbon atoms. After converting the obtained values into the gas phase heats of combustion and subtracting one value from another, the resulting mean resonance energy of 184 kJ/mol was obtained. The proposed method can be offered as an experiment for an undergraduate physical chemistry lab curriculum. PMID:26997668

  6. Emission and Size Distribution of Particle-bound Polycyclic Aromatic Hydrocarbons from Residential Wood Combustion

    PubMed Central

    Shen, Guofeng; Wei, Siye; Zhang, Yanyan; Wang, Bin; Wang, Rong; Shen, Huizhong; Li, Wei; Huang, Ye; Chen, Yuanchen; Chen, Han; Tao, Shu

    2015-01-01

    Emissions and size distributions of 28 particle-bound polycyclic aromatic hydrocarbons (PAHs) from residential combustion of 19 fuels in a domestic cooking stove in rural China were studied. Measured emission factors of total PAHs were 1.79±1.55, 12.1±9.1, and 5.36±4.46 mg/kg for fuel wood, brushwood, and bamboo, respectively. Approximate 86.7, 65.0, and 79.7% of the PAHs were associated with fine particulate matter with size less than 2.1 µm for these three types of fuels. Statistically significant difference in emission factors and size distributions of particle-bound PAHs between fuel wood and brushwood was observed, with the former had lower emission factors but more PAHs in finer PM. Mass fraction of the fine particles associated PAHs was found to be positively correlated with fuel density and moisture, and negatively correlated with combustion efficiency. Low and high molecular weight PAHs segregated into the coarse and fine PM, respectively. The high accumulation tendency of the PAHs from residential wood combustion in fine particles implies strong adverse health impact. PMID:25678760

  7. Complex reaction networks in high temperature hydrocarbon chemistry.

    PubMed

    Mutlay, İbrahim; Restrepo, Albeiro

    2015-03-28

    Complex chemical reaction mechanisms of high temperature hydrocarbon decomposition are represented as networks and their underlying graph topologies are analyzed as a dynamic system. As model reactants, 1,3-butadiene, acetylene, benzene, ethane, ethylene, methane, methyl isobutyl ketone (MIBK) and toluene are chosen in view of their importance for the global environment, energy technologies as well as their quantum chemical properties. Accurate kinetic mechanisms are computationally simulated and converted to bipartite graphs for the incremental conversion steps of the main reactant. Topological analysis of the resulting temporal networks reveals novel features unknown to classical chemical kinetics theory. The time-dependent percolation behavior of the chemical reaction networks shows infinite order phase transition and a unique correlation between the percolation thresholds and electron distribution of the reactants. These observations are expected to yield important applications in the development of a new theoretical perspective to chemical reactions and technological processes e.g. inhibition of greenhouse gases, efficient utilization of fossil fuels, and large scale carbon nanomaterial production. PMID:25720589

  8. Chemistry and combustion of fit-for-purpose biofuels.

    PubMed

    Rothamer, David A; Donohue, Timothy J

    2013-06-01

    From the inception of internal combustion engines, biologically derived fuels (biofuels) have played a role. Nicolaus Otto ran a predecessor to today's spark-ignition engine with an ethanol fuel blend in 1860. At the 1900 Paris world's fair, Rudolf Diesel ran his engine on peanut oil. Over 100 years of petroleum production has led to consistency and reliability of engines that demand standardized fuels. New biofuels can displace petroleum-based fuels and produce positive impacts on the environment, the economy, and the use of local energy sources. This review discusses the combustion, performance and other requirements of biofuels that will impact their near-term and long-term ability to replace petroleum fuels in transportation applications. PMID:23664492

  9. Emission of Oxygenated Polycyclic Aromatic Hydrocarbons from Indoor Solid Fuel Combustion

    PubMed Central

    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

    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. PMID:21375317

  10. Bioavailability and potential carcinogenicity of polycyclic aromatic hydrocarbons from wood combustion particulate matter in vitro.

    PubMed

    Gauggel-Lewandowski, Susanne; Heussner, Alexandra H; Steinberg, Pablo; Pieterse, Bart; van der Burg, Bart; Dietrich, Daniel R

    2013-11-25

    Due to increasing energy demand and limited fossil fuels, renewable energy sources have gained in importance. Particulate matter (PM) in general, but also PM from the combustion of wood is known to exert adverse health effects in human. These are often related to specific toxic compounds adsorbed to the PM surface, such as polycyclic aromatic hydrocarbons (PAH), of which some are known human carcinogens. This study focused on the bioavailability of PAHs and on the tumor initiation potential of wood combustion PM, using the PAH CALUX® reporter gene assay and the BALB/c 3T3 cell transformation assay, respectively. For this, both cell assays were exposed to PM and their respective organic extracts from varying degrees of combustion. The PAH CALUX® experiments demonstrated a concentration-response relationship matching the PAHs detected in the samples. Contrary to expectations, PM samples from complete (CC) and incomplete combustion (IC) provided for a stronger and weaker response, respectively, suggesting that PAH were more readily bioavailable in PM from CC. These findings were corroborated via PAH spiking experiments indicating that IC PM contains organic components that strongly adsorb PAH thereby reducing their bioavailability. The results obtained with organic extracts in the cell transformation assay presented the highest potential for carcinogenicity in samples with high PAH contents, albeit PM from CC also demonstrated a carcinogenic potential. In conclusion, the in vitro assays employed emphasize that CC produces PM with low PAH content however with a general higher bioavailability and thus with a nearly similar carcinogenic potential than IC PM. PMID:23796820

  11. Physics and chemistry of plasma-assisted combustion.

    PubMed

    Starikovskiy, Andrey

    2015-08-13

    There are several mechanisms that affect a gas when using discharge plasma to initiate combustion or to stabilize a flame. There are two thermal mechanisms-the homogeneous and inhomogeneous heating of the gas due to 'hot' atom thermalization and vibrational and electronic energy relaxation. The homogeneous heating causes the acceleration of the chemical reactions. The inhomogeneous heating generates flow perturbations, which promote increased turbulence and mixing. Non-thermal mechanisms include the ionic wind effect (the momentum transfer from an electric field to the gas due to the space charge), ion and electron drift (which can lead to additional fluxes of active radicals in the gradient flows in the electric field) and the excitation, dissociation and ionization of the gas by e-impact, which leads to non-equilibrium radical production and changes the kinetic mechanisms of ignition and combustion. These mechanisms, either together or separately, can provide additional combustion control which is necessary for ultra-lean flames, high-speed flows, cold low-pressure conditions of high-altitude gas turbine engine relight, detonation initiation in pulsed detonation engines and distributed ignition control in homogeneous charge-compression ignition engines, among others. Despite the lack of knowledge in mechanism details, non-equilibrium plasma demonstrates great potential for controlling ultra-lean, ultra-fast, low-temperature flames and is extremely promising technology for a very wide range of applications. PMID:26170435

  12. Physics and chemistry of plasma-assisted combustion

    PubMed Central

    Starikovskiy, Andrey

    2015-01-01

    There are several mechanisms that affect a gas when using discharge plasma to initiate combustion or to stabilize a flame. There are two thermal mechanisms—the homogeneous and inhomogeneous heating of the gas due to ‘hot’ atom thermalization and vibrational and electronic energy relaxation. The homogeneous heating causes the acceleration of the chemical reactions. The inhomogeneous heating generates flow perturbations, which promote increased turbulence and mixing. Non-thermal mechanisms include the ionic wind effect (the momentum transfer from an electric field to the gas due to the space charge), ion and electron drift (which can lead to additional fluxes of active radicals in the gradient flows in the electric field) and the excitation, dissociation and ionization of the gas by e-impact, which leads to non-equilibrium radical production and changes the kinetic mechanisms of ignition and combustion. These mechanisms, either together or separately, can provide additional combustion control which is necessary for ultra-lean flames, high-speed flows, cold low-pressure conditions of high-altitude gas turbine engine relight, detonation initiation in pulsed detonation engines and distributed ignition control in homogeneous charge-compression ignition engines, among others. Despite the lack of knowledge in mechanism details, non-equilibrium plasma demonstrates great potential for controlling ultra-lean, ultra-fast, low-temperature flames and is extremely promising technology for a very wide range of applications. PMID:26170435

  13. Regulated and speciated hydrocarbon emissions from a catalyst equipped internal combustion engine

    NASA Astrophysics Data System (ADS)

    Poulopoulos, S. G.; Samaras, D. P.; Philippopoulos, C. J.

    In the present work, the effect of engine operating conditions on its exhaust emissions and on catalytic converter operation is studied. A 4-cylinder OPEL 1.6 l internal combustion engine equipped with a hydraulic brake dynamometer was used in all the experiments. For exhaust emissions treatment a typical three-way catalyst was used. The highest hydrocarbon and carbon monoxide engine-out emissions were observed at engine power 2-4 HP. These emissions were decreased as the engine power was increased up to 20 HP. Among the various compounds detected in exhaust emissions, the following ones were monitored at engine and catalyst outlet: methane, hexane, ethylene, acetaldehyde, acetone, benzene, toluene and acetic acid. The concentration of each compound in the catalytic converter effluent was in the range 45-132, 5-12, 10-125, 15-22, 3-7, 3-12, 2-9, 0-6 ppm, respectively. After the required temperature for catalyst operation had been achieved, carbon monoxide tailpipe emissions were dramatically decreased and the observed hydrocarbon conversions were also high. Methane was the most resistant compound to oxidation while ethylene was the most degradable compound over the catalyst. The order from the easiest to the most resistant to oxidation compound was: Alkene>Aromatic>Aldehyde>Ketone>Alkane.

  14. Emissions of Parent, Nitro, and Oxygenated Polycyclic Aromatic Hydrocarbons from Residential Wood Combustion in Rural China

    PubMed Central

    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.

    2012-01-01

    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 (EFPAH28), 9 nPAHs (EFPAHn9) and 4 oPAHs (EFPAHo4) were measured for residential combustion of 27 wood fuels in rural China. The measured EFPAH28, EFPAHn9, and EFPAHo4 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

  15. Characterization of polycyclic aromatic hydrocarbon particulate and gaseous emissions from polystyrene combustion

    SciTech Connect

    Durlak, S.K.; Biswas, P.; Shi, J.; Bernhard, M.J.

    1998-08-01

    The partitioning of polycyclic aromatic hydrocarbons (PAHs) between the particulate and gaseous phases resulting from the combustion of polystyrene was studied. A vertical tubular flow furnace was used to incinerate polystyrene spheres at different combustion temperatures to determine the effect of temperature and polystyrene feed size on the particulate and gaseous emissions and their chemical composition. The furnace reactor exhaust was sampled using real-time instruments (differential mobility particle sizer and/or optical particle counter) to determine the particle size distribution. For chemical composition analyses, the particles were either collected on Teflon filters or split into eight size fractions using a cascade impactor with filter media substrates, while the gaseous products were collected on XAD-2 adsorbent. Gas chromatography/mass spectroscopy was used to identify and quantify the specific PAH species, their partitioning between the gas and particulate phases, and their distribution as a function of emission particle size. The total mass and number of PAH species in both the particulate and gas phases were found to decrease with increasing incineration temperature and decreasing polystyrene feed size, while the mean diameter of the particles increases with increasing incineration temperature and decreasing feed size. In addition, the PAH species in the particulate phase were found to be concentrated in the smaller aerosol sizes.

  16. Thermodynamic and transport combustion properties of hydrocarbons with air. Part 1: Properties in SI units

    NASA Technical Reports Server (NTRS)

    Gordon, S.

    1982-01-01

    Thermodynamic and transport combustion properties were calculated for a wide range of conditions for the reaction of hydrocarbons with air. Three hydrogen-carbon atom ratios (H/C = 1.7, 2.0, 2.1) were selected to represent the range of aircraft fuels. For each of these H/C ratios, combustion properties were calculated for the following conditions: Equivalence ratio: 0, 0.25, 0.5, 0.75, 1.0, 1.25 Water - dry air mass ratio: 0, 0.03 Pressure, kPa: 1.01325, 10.1325, 101.325, 1013.25, 5066.25 (or in atm: 0.01, 0.1, 1, 10, 50) Temperature, K: every 10 degrees from 200 to 900 K; every 50 degrees from 900 to 3000 K Temperature, R: every 20 degrees from 360 to 1600 R; very 100 degrees from 1600 to 5400 R. The properties presented are composition, density, molecular weight, enthalphy, entropy, specific heat at constant pressure, volume derivatives, isentropic exponent, velocity of sound, viscosity, thermal conductivity, and Prandtl number. Property tables are based on composites that were calculated by assuming both: (1) chemical equilibrium (for both homogeneous and heterogeneous phases) and (2) constant compositions for all temperatures. Properties in SI units are presented in this report for the Kelvin temperature schedules.

  17. Thermodynamic and transport combustion properties of hydrocarbons with air. Part 1: Properties in SI units

    NASA Astrophysics Data System (ADS)

    Gordon, S.

    1982-07-01

    Thermodynamic and transport combustion properties were calculated for a wide range of conditions for the reaction of hydrocarbons with air. Three hydrogen-carbon atom ratios (H/C = 1.7, 2.0, 2.1) were selected to represent the range of aircraft fuels. For each of these H/C ratios, combustion properties were calculated for the following conditions: Equivalence ratio: 0, 0.25, 0.5, 0.75, 1.0, 1.25 Water - dry air mass ratio: 0, 0.03 Pressure, kPa: 1.01325, 10.1325, 101.325, 1013.25, 5066.25 (or in atm: 0.01, 0.1, 1, 10, 50) Temperature, K: every 10 degrees from 200 to 900 K; every 50 degrees from 900 to 3000 K Temperature, R: every 20 degrees from 360 to 1600 R; very 100 degrees from 1600 to 5400 R. The properties presented are composition, density, molecular weight, enthalphy, entropy, specific heat at constant pressure, volume derivatives, isentropic exponent, velocity of sound, viscosity, thermal conductivity, and Prandtl number. Property tables are based on composites that were calculated by assuming both: (1) chemical equilibrium (for both homogeneous and heterogeneous phases) and (2) constant compositions for all temperatures. Properties in SI units are presented in this report for the Kelvin temperature schedules.

  18. Polycyclic aromatic hydrocarbon emissions from the combustion of alternative fuels in a gas turbine engine.

    PubMed

    Christie, Simon; Raper, David; Lee, David S; Williams, Paul I; Rye, Lucas; Blakey, Simon; Wilson, Chris W; Lobo, Prem; Hagen, Donald; Whitefield, Philip D

    2012-06-01

    We report on the particulate-bound polycyclic aromatic hydrocarbons (PAH) in the exhaust of a test-bed gas turbine engine when powered by Jet A-1 aviation fuel and a number of alternative fuels: Sasol fully synthetic jet fuel (FSJF), Shell gas-to-liquid (GTL) kerosene, and Jet A-1/GTL 50:50 blended kerosene. The concentration of PAH compounds in the exhaust emissions vary greatly between fuels. Combustion of FSJF produces the greatest total concentration of PAH compounds while combustion of GTL produces the least. However, when PAHs in the exhaust sample are measured in terms of the regulatory marker compound benzo[a]pyrene, then all of the alternative fuels emit a lower concentration of PAH in comparison to Jet A-1. Emissions from the combustion of Jet A-1/GTL blended kerosene were found to have a disproportionately low concentration of PAHs and appear to inherit a greater proportion of the GTL emission characteristics than would be expected from volume fraction alone. The data imply the presence of a nonlinear relation between fuel blend composition and the emission of PAH compounds. For each of the fuels, the speciation of PAH compounds present in the exhaust emissions were found to be remarkably similar (R(2) = 0.94-0.62), and the results do provide evidence to support the premise that PAH speciation is to some extent indicative of the emission source. In contrast, no correlation was found between the PAH species present in the fuel with those subsequently emitted in the exhaust. The results strongly suggests that local air quality measured in terms of the particulate-bound PAH burden could be significantly improved by the use of GTL kerosene either blended with or in place of Jet A-1 kerosene. PMID:22534092

  19. Emission, distribution and toxicity of polycyclic aromatic hydrocarbons (PAHs) during municipal solid waste (MSW) and coal co-combustion.

    PubMed

    Peng, Nana; Li, Yi; Liu, Zhengang; Liu, Tingting; Gai, Chao

    2016-09-15

    Emission and distribution characteristics of polycyclic aromatic hydrocarbons (PAHs) were investigated during municipal solid waste (MSW) and coal combustion alone and MSW/coal blend (MSW weight fraction of 25%) co-combustion within a temperature range of 500°C-900°C. The results showed that for all combustion experiments, flue gas occupied the highest proportion of total PAHs and fly ash contained more high-ring PAHs. Moreover, the 3- and 4-ring PAHs accounted for the majority of total PAHs and Ant or Phe had the highest concentrations. Compared to coal, MSW combustion generated high levels of total PAHs with the range of 111.28μg/g-10,047.22μg/g and had high toxicity equivalent value (TEQ). MSW/coal co-combustion generated the smallest amounts of total PAHs and had the lowest TEQ than MSW and coal combustion alone. Significant synergistic interactions occurred between MSW and coal during co-combustion and the interactions suppressed the formation of PAHs, especially hazardous high-ring PAHs and decreased the TEQ. The present study indicated that the reduction of the yield and toxicity of PAHs can be achieved by co-combustion of MSW and coal. PMID:27265733

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

    SciTech Connect

    Hongcang Zhou; Baosheng Jin; Rui Xiao; Zhaoping Zhong; Yaji Huang

    2009-04-15

    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.

  1. 3-D CFD Simulation and Validation of Oxygen-Rich Hydrocarbon Combustion in a Gas-Centered Swirl Coaxial Injector using a Flamelet-Based Approach

    NASA Technical Reports Server (NTRS)

    Richardson, Brian; Kenny, Jeremy

    2015-01-01

    Injector design is a critical part of the development of a rocket Thrust Chamber Assembly (TCA). Proper detailed injector design can maximize propulsion efficiency while minimizing the potential for failures in the combustion chamber. Traditional design and analysis methods for hydrocarbon-fuel injector elements are based heavily on empirical data and models developed from heritage hardware tests. Using this limited set of data produces challenges when trying to design a new propulsion system where the operating conditions may greatly differ from heritage applications. Time-accurate, Three-Dimensional (3-D) Computational Fluid Dynamics (CFD) modeling of combusting flows inside of injectors has long been a goal of the fluid analysis group at Marshall Space Flight Center (MSFC) and the larger CFD modeling community. CFD simulation can provide insight into the design and function of an injector that cannot be obtained easily through testing or empirical comparisons to existing hardware. However, the traditional finite-rate chemistry modeling approach utilized to simulate combusting flows for complex fuels, such as Rocket Propellant-2 (RP-2), is prohibitively expensive and time consuming even with a large amount of computational resources. MSFC has been working, in partnership with Streamline Numerics, Inc., to develop a computationally efficient, flamelet-based approach for modeling complex combusting flow applications. In this work, a flamelet modeling approach is used to simulate time-accurate, 3-D, combusting flow inside a single Gas Centered Swirl Coaxial (GCSC) injector using the flow solver, Loci-STREAM. CFD simulations were performed for several different injector geometries. Results of the CFD analysis helped guide the design of the injector from an initial concept to a tested prototype. The results of the CFD analysis are compared to data gathered from several hot-fire, single element injector tests performed in the Air Force Research Lab EC-1 test facility

  2. The effects of detailed chemistry and transport on microgravity droplet combustion

    NASA Technical Reports Server (NTRS)

    Marchese, A. J.; Lee, J. C.; Held, T. J.; Dryer, F. L.

    1995-01-01

    A brief overview of recent advances in the theoretical study of microgravity droplet combustion is presented. Much of this work has centered on the development and utilization of sphero-symmetric transient numerical models which consider detailed gas phase chemistry and transport as well as energy and/or species transport within a regressing condensed phase. Numerical results for microgravity combustion and vaporization of methanol, methanol/water, heptane, and heptane/hexadecane droplets are summarized along with refinements in chemical kinetics and the development of a new two-dimensional axi-symmetric model.

  3. Polycyclic aromatic hydrocarbons and organic matter associated to particulate matter emitted from atmospheric fluidized bed coal combustion

    SciTech Connect

    Mastral, A.M.; Callen, M.S.; Garcia, T.

    1999-09-15

    The polycyclic aromatic hydrocarbons (PAH) and the organic matter (OM) content associated with particulate matter (PM) emissions from atmospheric fluidized bed coal combustion have been studied. The two main aims of the work have been (a) to study OM and PAH emissions as a function of the coal fluidized bed combustion (FBC) variables in solid phase and (b) to check if there is any correlation between OM and PAH contained in the PM. The combustion was carried out in a laboratory scale plant at different combustion conditions: temperature, percentage of oxygen excess, and total air flow. PAH associated on the particulate matter have been analyzed by fluorescence spectroscopy in the synchronous mode (FS) after PM extraction by sonication with dimethylformamide (DMF). It can be concluded that there is not a direct relationship between the OM content and the PAH supported in the PM emitted. In addition, neither PM or OM show dependence between themselves.

  4. A Two-Zone Multigrid Model for SI Engine Combustion Simulation Using Detailed Chemistry

    DOE PAGESBeta

    Ge, Hai-Wen; Juneja, Harmit; Shi, Yu; Yang, Shiyou; Reitz, Rolf D.

    2010-01-01

    An efficient multigrid (MG) model was implemented for spark-ignited (SI) engine combustion modeling using detailed chemistry. The model is designed to be coupled with a level-set-G-equation model for flame propagation (GAMUT combustion model) for highly efficient engine simulation. The model was explored for a gasoline direct-injection SI engine with knocking combustion. The numerical results using the MG model were compared with the results of the original GAMUT combustion model. A simpler one-zone MG model was found to be unable to reproduce the results of the original GAMUT model. However, a two-zone MG model, which treats the burned and unburned regionsmore » separately, was found to provide much better accuracy and efficiency than the one-zone MG model. Without loss in accuracy, an order of magnitude speedup was achieved in terms of CPU and wall times. To reproduce the results of the original GAMUT combustion model, either a low searching level or a procedure to exclude high-temperature computational cells from the grouping should be applied to the unburned region, which was found to be more sensitive to the combustion model details.« less

  5. Investigation and Optimization of Biodiesel Chemistry for HCCI Combustion

    SciTech Connect

    Bunting, Bruce G; Bunce, Michael; Joyce, Blake; Crawford, Robert W

    2011-01-01

    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.

  6. Investigation and Optimization of Biodiesel Chemistry for HCCI Combustion

    SciTech Connect

    Bunting, Bruce G.; Bunce, Michael; Joyce, Blake; Crawford, Robert W.

    2014-06-23

    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.

  7. Nitro Polycyclic Aromatic Hydrocarbons in Particulate Matter Emitted by the Combustion of Diesel and Biodiesel

    NASA Astrophysics Data System (ADS)

    Valle-Hernández, B. L.; Amador-Muñoz, O.; Jazcilevich, A. D.; Santos-Medina, G. L.; Hernández-Lopéz, E.; Villalobos-Pietrini, R.

    2013-05-01

    The rapid population growth in large urban areas, has resulted in a precipitous increase in the consumption of fossil fuels, mainly by the transport sector, diesel vehicles are a significant source of air pollution by particulate matter emissions, damaging the population health, because of the size and composition of these particles, as they may contain carcinogenic organic compounds such as polycyclic aromatic hydrocarbons and their derivatives, nitro-PAH. This study focused on analysis of nitro-PAH contained in particles emitted from diesel engines fuelled with biodiesel blends (B5, B10 and B16.67) to different driving cycles (rpm and torque), and to compare their concentrations with emissions from current diesel. A diesel truck engine was used in the laboratory for collect particulate mass emitted directly from the exhaust. Mass of particles and nitro-PAH were determined by gas chromatography-mass spectrometry using negative chemical ionization. No reduction was observed in the particles mass per second by using biodiesel relative to diesel (p > 0.1). Seven nitro-PAH were observed in samples: 1-nitronaphthalene, 2-nitronaphthalene, 9-nitroanthracene, 3-nitrophenanthrene, 1,8-dinitronaphthalene, 1-nitropyrene and 1,6-dinitropyrene. 1-nitropyrene showed the highest mass concentration in diesel and in all blends of biodiesel, followed by 3-nitrophenanthrene. Emissions reduction in biodiesel combustion with respect to diesel combustion were observed for 1-nitropyrene: 50 %, in all blends (B5, B10 and B16.67) and for 3-nitrophenanthrene: 55 % in B5, 72 % in B10 and 64 % in B16.67.

  8. A Combustion Chemistry Analysis of Carbonate Solvents in Li-Ion Batteries

    SciTech Connect

    Harris, S J; Timmons, A; Pitz, W J

    2008-11-13

    Under abusive conditions Li-ion batteries can rupture, ejecting electrolyte and other flammable gases. In this paper we consider some of the thermochemical properties of these gases that will determine whether they ignite and how energetically they burn. We show that flames of carbonate solvents are fundamentally less energetic than those of conventional hydrocarbons. An example of this difference is given using a recently developed mechanism for dimethyl carbonate (DMC) combustion, where we show that a diffusion flame burning DMC has only half the peak energy release rate of an analogous propane flame. We find a significant variation among the carbonate solvents in the factors that are important to determining flammability, such as combustion enthalpy and vaporization enthalpy. This result suggests that thermochemical and kinetic factors might well be considered when choosing solvent mixtures.

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

    NASA Technical Reports Server (NTRS)

    Gordon, S.

    1982-01-01

    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.

  10. A combustion chemistry analysis of carbonate solvents used in Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Harris, Stephen J.; Timmons, Adam; Pitz, William J.

    Under abusive conditions Li-ion cells can rupture, ejecting electrolyte and other flammable gases. In this paper we consider some of the thermochemical and combustion properties of these gases that determine whether they ignite and how energetically they burn. We find a significant variation among the carbonate solvents in the factors that are important to determining flammability, such as combustion enthalpy and vaporization enthalpy. We also show that flames of carbonate solvents are fundamentally less energetic than those of conventional hydrocarbons. An example of this contrast is given using a recently developed mechanism for dimethyl carbonate (DMC) combustion, where we show that a diffusion flame burning DMC has only half the peak heat release rate of an analogous propane flame. Interestingly, peak temperatures differ by only 25%. We argue that heat release rate is a more useful parameter than temperature when evaluating the likelihood that a flame in one cell will ignite a neighboring cell. Our results suggest that thermochemical and combustion property factors might well be considered when choosing solvent mixtures when flammability is a concern.

  11. Formation of oxides of nitrogen in monodisperse spray combustion of hydrocarbon fuels

    NASA Technical Reports Server (NTRS)

    Nizami, A. A.; Singh, S.; Cernansky, N. P.

    1982-01-01

    Experimental results of exit plane NO/NO(x) emissions from atmospheric monodisperse fuel spray combustion are presented. Six different hydrocarbon fuels were studied: isopropanol, n-propanol, n-octane, iso-octane, n-heptane and methanol. The results indicate an optimum droplet size for minimizing NO/NO(x) production for all of the test fuels. At the optimum droplet diameter, reductions in NO/NO(x) relative to the NO(x) occurred at droplet diameters of 55 and 48 microns respectively, as compared to a 50-micron droplet size for isopropanol. The occurrence of the minimum NO(x) point at different droplet diameters for the different fuels appears to be governed by the extent of prevaporization of the fuel in the spray, and is consistent with theoretical calculations based on each fuel's physical properties. Estimates are also given for the behavior of heavy fuels and of polydisperse fuel sprays in shifting the minimum NO(x) point compared to a monodisperse situation.

  12. Combustion performance and heat transfer characterization of LOX/hydrocarbon type propellants

    NASA Technical Reports Server (NTRS)

    Michel, R. W.

    1983-01-01

    An evaluation liquid oxygen (LOX) and various hydrocarbon fuels as low cost alternative propellants suitable for future space transportation system applications was done. The emphasis was directed toward low earth orbit maneuvering engine and reaction control engine systems. The feasibility of regeneratively cooling an orbit maneuvering thruster was analytically determined over a range of operating conditions from 100 to 1000 psia chamber pressure and 1000 to 10,000-1bF thrust, and specific design points were analyzed in detail for propane, methane, RP-1, ammonia, and ethanol; similar design point studies were performed for a film-cooled reaction control thruster. Heat transfer characteristics of propane were experimentally evaluated in heated tube tests. Forced convection heat transfer coefficients were determined. Seventy-seven hot firing tests were conducted with LOX/propane and LOX/ethanol, for a total duration of nearly 1400 seconds, using both heat sink and water-cooled calorimetric chambers. Combustion performance and stability and gas-side heat transfer characteristics were evaluated.

  13. Development of a Raman spectroscopy technique to detect alternate transportation fuel hydrocarbon intermediates in complex combustion environments.

    SciTech Connect

    Ekoto, Isaac W.; Barlow, Robert S.

    2012-12-01

    Spontaneous Raman spectra for important hydrocarbon fuels and combustion intermediates were recorded over a range of low-to-moderate flame temperatures using the multiscalar measurement facility located at Sandia/CA. Recorded spectra were extrapolated to higher flame temperatures and then converted into empirical spectral libraries that can readily be incorporated into existing post-processing analysis models that account for crosstalk from overlapping hydrocarbon channel signal. Performance testing of the developed libraries and reduction methods was conducted through an examination of results from well-characterized laminar reference flames, and was found to provide good agreement. The diagnostic development allows for temporally and spatially resolved flame measurements of speciated hydrocarbon concentrations whose parent is more chemically complex than methane. Such data are needed to validate increasingly complex flame simulations.

  14. Carbon deposition model for oxygen-hydrocarbon combustion. Task 6: Data analysis and formulation of an empirical model

    NASA Technical Reports Server (NTRS)

    Makel, Darby B.; Rosenberg, Sanders D.

    1990-01-01

    The formation and deposition of carbon (soot) was studied in the Carbon Deposition Model for Oxygen-Hydrocarbon Combustion Program. An empirical, 1-D model for predicting soot formation and deposition in LO2/hydrocarbon gas generators/preburners was derived. The experimental data required to anchor the model were identified and a test program to obtain the data was defined. In support of the model development, cold flow mixing experiments using a high injection density injector were performed. The purpose of this investigation was to advance the state-of-the-art in LO2/hydrocarbon gas generator design by developing a reliable engineering model of gas generator operation. The model was formulated to account for the influences of fluid dynamics, chemical kinetics, and gas generator hardware design on soot formation and deposition.

  15. The Role of Nitrogen in Titan’s Upper Atmospheric Hydrocarbon Chemistry Over the Solar Cycle

    NASA Astrophysics Data System (ADS)

    Luspay-Kuti, A.; Mandt, K. E.; Westlake, J. H.; Plessis, S.; Greathouse, T. K.

    2016-06-01

    Titan’s thermospheric photochemistry is primarily driven by solar radiation. Similarly to other planetary atmospheres, such as Mars’, Titan’s atmospheric structure is also directly affected by variations in the solar extreme-UV/UV output in response to the 11-year-long solar cycle. Here, we investigate the influence of nitrogen on the vertical production, loss, and abundance profiles of hydrocarbons as a function of the solar cycle. Our results show that changes in the atmospheric nitrogen atomic density (primarily in its ground state N(4S)) as a result of photon flux variations have important implications for the production of several minor hydrocarbons. The solar minimum enhancement of CH3, C2H6, and C3H8, despite the lower CH4 photodissociation rates compared with solar maximum conditions, is explained by the role of N(4S). N(4S) indirectly controls the altitude of termolecular versus bimolecular chemical regimes through its relationship with CH3. When in higher abundance during solar maximum at lower altitudes, N(4S) increases the importance of bimolecular CH3 + N(4S) reactions producing HCN and H2CN. The subsequent remarkable CH3 loss and decrease in the CH3 abundance at lower altitudes during solar maximum affects the overall hydrocarbon chemistry.

  16. Fundamental combustion research applied to pollution formation. Volume 2a. Physics and chemistry of two-phase systems: flame-combustion processes

    SciTech Connect

    Seeker, W.R.; Heap, M.P.

    1988-01-01

    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 IIa describes mechanisms of fuel nitrogen processing in large-scale utility flames burning pulverized coal and heavy fuel oils, in three parts: (1) high-temperature decomposition and combustion of pulverized-coal (EERC); (2) detailed measurement of long pulverized coal flames for the characterization of pollutant formation (International Flame Research Foundation); and (3) heavy-oil combustion in shear layers (United Technologies Research Center).

  17. On the radiolysis of ethylene ices by energetic electrons and implications to the extraterrestrial hydrocarbon chemistry

    SciTech Connect

    Zhou, Li; Maity, Surajit; Abplanalp, Matt; Turner, Andrew; Kaiser, Ralf I.

    2014-07-20

    The chemical processing of ethylene ices (C{sub 2}H{sub 4}) by energetic electrons was investigated at 11 K to simulate the energy transfer processes and synthesis of new molecules induced by secondary electrons generated in the track of galactic cosmic ray particles. A combination of Fourier transform infrared spectrometry (solid state) and quadrupole mass spectrometry (gas phase) resulted in the identification of six hydrocarbon molecules: methane (CH{sub 4}), the C2 species acetylene (C{sub 2}H{sub 2}), ethane (C{sub 2}H{sub 6}), the ethyl radical (C{sub 2}H{sub 5}), and—for the very first time in ethylene irradiation experiments—the C4 hydrocarbons 1-butene (C{sub 4}H{sub 8}) and n-butane (C{sub 4}H{sub 10}). By tracing the temporal evolution of the newly formed molecules spectroscopically online and in situ, we were also able to fit the kinetic profiles with a system of coupled differential equations, eventually providing mechanistic information, reaction pathways, and rate constants on the radiolysis of ethylene ices and the inherent formation of smaller (C1) and more complex (C2, C4) hydrocarbons involving carbon-hydrogen bond ruptures, atomic hydrogen addition processes, and radical-radical recombination pathways. We also discuss the implications of these results on the hydrocarbon chemistry on Titan's surface and on ice-coated, methane-bearing interstellar grains as present in cold molecular clouds such as TMC-1.

  18. The chemistry of biogenic hydrocarbons at a rural site in eastern Canada

    NASA Astrophysics Data System (ADS)

    Biesenthal, T. A.; Bottenheim, J. W.; Shepson, P. B.; Li, S.-M.; Brickell, P. C.

    1998-10-01

    An intensive field study was undertaken in southern Nova Scotia, on the east coast of Canada, for several weeks during the summer of 1996 as part of the North American Research Strategy for Tropospheric Ozone - Canada East (NARSTO-CE) 1996 field measurement campaign. Clean air conditions prevailed during most of the study period, which allowed an examination of biogenic hydrocarbon chemistry with minimal influence from anthropogenic pollutants. Low NOx mixing ratios during the study had an impact on the ratio of isoprene's oxidation products methyl vinyl ketone (MVK) and methacrolein (MACR) to isoprene. The effects include changes to the fate of isoprene peroxy radicals and to the concentration of OH compared to conditions of higher [NOx]. Comparison to other studies indicate that there is a relationship between the ratio (MVK+MACR)/isoprene and the mixing ratio of NOx. Biogenic hydrocarbons were the dominant reactive volatile organic compound (VOC) precursors to ozone production in this region, although the net ozone production rate predicted by a box-model simulation of the measurement data was only <1 ppbv h-1. The evidence confirms that ozone production at this site is very NOx-sensitive. Model simulations indicated that the ozonolysis of biogenic hydrocarbons is an important source of the hydroxyl radical at this site and that OH was, in fact, the dominant oxidant during the nighttime under the observed low NOx conditions. Although the OH source did affect the nighttime mixing ratios of biogenic hydrocarbons, it could not fully explain the rapid nocturnal decay of isoprene observed on most evenings.

  19. Adaptation of Combustion Principles to Aircraft Propulsion. Volume I; Basic Considerations in the Combustion of Hydrocarbon Fuels with Air

    NASA Technical Reports Server (NTRS)

    Barnett, Henry C (Editor); Hibbard, Robert R (Editor)

    1955-01-01

    The report summarizes source material on combustion for flight-propulsion engineers. First, several chapters review fundamental processes such as fuel-air mixture preparation, gas flow and mixing, flammability and ignition, flame propagation in both homogenous and heterogenous media, flame stabilization, combustion oscillations, and smoke and carbon formation. The practical significance and the relation of these processes to theory are presented. A second series of chapters describes the observed performance and design problems of engine combustors of the principal types. An attempt is made to interpret performance in terms of the fundamental processes and theories previously reviewed. Third, the design of high-speed combustion systems is discussed. Combustor design principles that can be established from basic considerations and from experience with actual combustors are described. Finally, future requirements for aircraft engine combustion systems are examined.

  20. Interactive computer modeling of combustion chemistry and coalescence-dispersion modeling of turbulent combustion

    NASA Technical Reports Server (NTRS)

    Pratt, D. T.

    1984-01-01

    An interactive computer code for simulation of a high-intensity turbulent combustor as a single point inhomogeneous stirred reactor was developed from an existing batch processing computer code CDPSR. The interactive CDPSR code was used as a guide for interpretation and direction of DOE-sponsored companion experiments utilizing Xenon tracer with optical laser diagnostic techniques to experimentally determine the appropriate mixing frequency, and for validation of CDPSR as a mixing-chemistry model for a laboratory jet-stirred reactor. The coalescence-dispersion model for finite rate mixing was incorporated into an existing interactive code AVCO-MARK I, to enable simulation of a combustor as a modular array of stirred flow and plug flow elements, each having a prescribed finite mixing frequency, or axial distribution of mixing frequency, as appropriate. Further increase the speed and reliability of the batch kinetics integrator code CREKID was increased by rewriting in vectorized form for execution on a vector or parallel processor, and by incorporating numerical techniques which enhance execution speed by permitting specification of a very low accuracy tolerance.

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

    PubMed

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

    2011-03-15

    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

  2. Investigation of the effect of chemistry models on the numerical predictions of the supersonic combustion of hydrogen

    SciTech Connect

    Kumaran, K.; Babu, V.

    2009-04-15

    In this numerical study, the influence of chemistry models on the predictions of supersonic combustion in a model combustor is investigated. To this end, 3D, compressible, turbulent, reacting flow calculations with a detailed chemistry model (with 37 reactions and 9 species) and the Spalart-Allmaras turbulence model have been carried out. These results are compared with earlier results obtained using single step chemistry. Hydrogen is used as the fuel and three fuel injection schemes, namely, strut, staged (i.e., strut and wall) and wall injection, are considered to evaluate the impact of the chemistry models on the flow field predictions. Predictions of the mass fractions of major species, minor species, dimensionless stagnation temperature, dimensionless static pressure rise and thrust percentage along the combustor length are presented and discussed. Overall performance metrics such as mixing efficiency and combustion efficiency are used to draw inferences on the nature (whether mixing- or kinetic-controlled) and the completeness of the combustion process. The predicted values of the dimensionless wall static pressure are compared with experimental data reported in the literature. The calculations show that multi step chemistry predicts higher and more wide spread heat release than what is predicted by single step chemistry. In addition, it is also shown that multi step chemistry predicts intricate details of the combustion process such as the ignition distance and induction distance. (author)

  3. Emission factors for carbonaceous particles and polycyclic aromatic hydrocarbons from residential coal combustion in China.

    PubMed

    Chen, Yingjun; Sheng, Guoying; Bi, Xinhui; Feng, Yanli; Mai, Bixian; Fu, Jiamo

    2005-03-15

    Emission factors of carbonaceous particles, including black carbon (BC) and organic carbon (OC), and polycyclic aromatic hydrocarbons (PAHs) were determined for five coals, which ranged in maturity from sub-bituminous to anthracite. They were burned in the form of honeycomb briquettes in a residential coalstove, one of the most common fuel/stove combinations in China. Smoke samples were taken through dilution sampling equipment, with a high volume sampler that could simultaneously collect emissions in both particulate and gaseous phases, and a cascade impactor that could segregate particles into six fractions. Particulate BC and OC were analyzed by a thermal-optical method, and PAHs in emissions of both phases were analyzed by GC-MS. Burning of bituminous coals produced the highest emission factors of particulate matter (12.91 g/kg), BC (0.28 g/kg), OC (7.82 g/kg), and 20 PAHs (210.6 mg/kg) on the basis of burned dry ash-free (daf) coal, while the anthracite honeycomb-briquette was the cleanest household coal fuel. The size-segregated results show that more than 94% of the particles were submicron, and calculated mass median aerodynamic diameters (MMAD) of all particles were under 0.3 microm. Based on the coal consumption in the residential sector of China, 290.24 Gg (gigagrams) of particulate matter, 5.36 Gg of BC, 170.33 Gg of OC, and 4.72 Gg of 20 PAHs mass were emitted annually from household honeycomb-briquette burning during 2000. Anthracite coal should be selected preferentially and more advanced burning conditions should be applied in domestic combustion, from the viewpoint of both climate change and adverse health effects. PMID:15819248

  4. Advanced modeling of nitrogen oxide emissions in circulating fluidized bed combustors: Parametric study of coal combustion and nitrogen compound chemistries

    SciTech Connect

    Kilpinen, P.; Kallio, S.; Hupa, M.

    1999-07-01

    This paper describes work-in-progress aimed at developing an emission model for circulating fluidized bed combustors using detailed homogeneous and heterogeneous chemical kinetics. The main emphasis is on nitrogen oxides (NO{sub x}, N{sub 2}O) but also unburned gases (CO, C{sub x}H{sub y}) and sulfur dioxide (SO{sub 2}) will be investigated in the long run. The hydrodynamics is described by a 1.5-dimensional model where the riser is divided into three regions: a dense bubbling bed at the bottom, a vigorously mixed splash zone, and a transport zone. The two latter zones are horizontally split into a core region and an annular region. The solids circulation rate is calculated from the known solids inventory and the pressure and mass balances over the entire circulation loop. The solids are divided into classes according to size and type or particle. The model assumes instantaneous fuel devolatilization at the bottom and an even distribution of volatiles in the suspension phase of the dense bed. For addition of secondary air, a complete penetration and an instantaneous mixing with the combustor gases in the core region is assumed. The temperature distribution is assumed to be known, and no energy balance is solved. A comprehensive kinetic scheme of about 300 elementary gas-phase reactions is used to describe the homogeneous oxidation of the volatiles including both hydrocarbon and volatile-nitrogen components (NH{sub 3}, HCN). Heterogeneous char combustion to CO and CO{sub 2}, and char-nitrogen conversion to NO, N{sub 2}O, and N{sub 2} are described by a single particle model that includes 15 reaction steps given in the form of 6 net reaction paths. In the paper, the model is briefly described. A special emphasis is put on the evaluation of chemistry submodels. Modeling results on nitrogen oxides' formation are compared with measured concentration profiles in a 12 MW CFBC riser from literature. The importance of accurate chemistry description on predictions is

  5. FUNDAMENTAL COMBUSTION RESEARCH APPLIED TO POLLUTION FORMATION. VOLUME 2A. PHYSICS AND CHEMISTRY OF TWO-PHASE SYSTEMS: FLAME COMBUSTION PROCESSES

    EPA Science Inventory

    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 IIa describes mechanisms of fuel nitrogen processing in large-scale ut...

  6. Compilation of chemical kinetic data for combustion chemistry. Part 2. Non-aromatic C, H, O, N, and S containing compounds (1983)

    SciTech Connect

    Westley, F.; Herron, J.T.; Cvetanovic, R.J.

    1987-12-01

    Chemical-kinetic data for reactions of importance in combustion chemistry are compiled. Experimental, theoretical, evaluated, or estimated rate constants are given for reactions of O, O/sub 3/, H, H/sub 2/, OH, HO/sub 2/, H/sub 2/O, N, N/sub 3/, NO, NO/sub 2/, N/sub 2/O, NH, NH/sub 2/, SH, H/sub 2/S, SO, SO/sub 2/, and the aliphatic, alicyclic, and heterocyclic saturated and unsaturated C1 to C15 hydrocarbons, alcohols, aldehydes, ketones, thiols, ethers, peroxides, amines, amides, and their free radicals. The data were taken from the literature published in 1983. Data omitted from Part 1 of the series, covering the period 1971 to 1982, are also included.

  7. Combustion performance and heat transfer characterization of LOX/hydrocarbon type propellants, volume 2

    NASA Technical Reports Server (NTRS)

    Schoenman, L.

    1983-01-01

    A data base which relates candidate design variables, such as injector type, acoustic cavity configuration, chamber length, fuel film-cooling, etc., to operational characteristics such as combustion efficiency, combustion stability, carbon deposition, and chamber gas-side heat flux was generated.

  8. Numerical study of supersonic combustion using a finite rate chemistry model

    NASA Technical Reports Server (NTRS)

    Chitsomboon, T.; Tiwari, S. N.; Kumar, A.; Drummond, J. P.

    1986-01-01

    The governing equations of two-dimensional chemically reacting flows are presented together with a global two-step chemistry model for H2-air combustion. The explicit unsplit MacCormack finite difference algorithm is used to advance the discrete system of the governing equations in time until convergence is attained. The source terms in the species equations are evaluated implicitly to alleviate stiffness associated with fast reactions. With implicit source terms, the species equations give rise to a block-diagonal system which can be solved very efficiently on vector-processing computers. A supersonic reacting flow in an inlet-combustor configuration is calculated for the case where H2 is injected into the flow from the side walls and the strut. Results of the calculation are compared against the results obtained by using a complete reaction model.

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

    SciTech Connect

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

    2012-01-01

    Core samples cut from full size commercial Fe- and Cu-zeolite selective catalytic reduction catalysts were exposed to a slipstream of raw engine exhaust from a 1.9-liter 4-cylinder diesel engine operating in conventional and premixed charge compression ignition (PCCI) combustion modes. Subsequently, the NO{sub x} reduction performance of the exposed catalysts was evaluated on a laboratory bench-reactor fed with simulated exhaust. The Fe-zeolite NO{sub x} conversion efficiency was significantly degraded, especially at low temperatures (<250 C), after the catalyst was exposed to the engine exhaust. The degradation of the Fe-zeolite performance was similar for both combustion modes. The Cu-zeolite was much more resistant to hydrocarbon (HC) fouling than the Fe-zeolite catalyst. In the case of the Cu-zeolite, PCCI exhaust had a more significant impact than the exhaust from conventional combustion on the NO{sub x} conversion efficiency. For all cases, the clean catalyst performance was recovered after heating to 600 C. Gas chromatography mass spectrometry analysis of the HCs adsorbed to the catalyst surface provided insights into the observed NO{sub x} reduction performance trends.

  10. Further investigation of the impact of the co-combustion of tire-derived fuel and petroleum coke on the petrology and chemistry of coal combustion products

    SciTech Connect

    Hower, J.C.; Robertson, J.D.; Elswick, E.R.; Roberts, J.M.; Brandsteder, K.; Trimble, A.S.; Mardon, S.M.

    2007-07-01

    A Kentucky cyclone-fired unit burns coal and tire-derived fuel, sometimes in combination with petroleum coke. A parallel pulverized combustion (pc) unit at the same plant burns the same coal, without the added fuels. The petrology, chemistry, and sulfur isotope distribution in the fuel and resulting combustion products was investigated for several configurations of the fuel blend. Zinc and Cd in the combustion products are primarily contributed from the tire-derived fuel, the V and Ni are primarily from the petroleum coke, and the As and Hg are probably largely from the coal. The sulfur isotope distribution in the cyclone unit is complicated due to the varying fuel sources. The electrostatic precipitator (ESP) array in the pc unit shows a subtle trend towards heavier S isotopic ratios in the cooler end of the ESP.

  11. Analysis of pollutant chemistry in combustion by in situ pulsed photoacoustic laser diagnostics

    NASA Astrophysics Data System (ADS)

    Stenberg, Jari; Hernberg, Rolf; Vattulainen, Juha

    1995-12-01

    A technique for gas analysis based on pulsed-laser-induced photoacoustic spectroscopy in the UV and the visible is presented. The laser-based technique and the associated analysis probe have been developed for the analysis of pollutant chemistry in fluidized beds and other combustion environments with limited or no optical access. The photoacoustic-absorption spectrum of the analyzed gas is measured in a test cell located at the end of a tubular probe. This test cell is subject to the prevailing temperature and pressure in the combustion process. The instrument response has been calibrated for N2O, NO, NO2, NH3, SO2, and H2 S at atmospheric pressure between 20 and 910 deg C. The response of the probe was found to increase with pressure for N2O, NO, NH 3, and NO2 up to 1.2 MPa pressure. The method and the probe have been used for detection and ranging of gas concentrations in a premixed methane flame. Some preliminary tests in a large 12-MW circulating bed boiler have also been done.

  12. Analysis of pollutant chemistry in combustion by in situ pulsed photoacoustic laser diagnostics.

    PubMed

    Stenberg, J; Hernberg, R; Vattulainen, J

    1995-12-20

    A technique for gas analysis based on pulsed-laser-induced photoacoustic spectroscopy in the UV and the visible is presented. The laser-based technique and the associated analysis probe have been developed for the analysis of pollutant chemistry in fluidized beds and other combustion environments with limited or no optical access. The photoacoustic-absorption spectrum of the analyzed gas is measured in a test cell located at the end of a tubular probe. This test cell is subject to the prevailing temperature and pressure in the combustion process. The instrument response has been calibrated for N(2)O, NO, NO(2), NH(3), SO(2), and H(2)S at atmospheric pressure between 20 and 910 °C. The response of the probe was found to increase with pressure for N(2)O, NO, NH(3), and NO(2) up to 1.2 MPa pressure. The method and the probe have been used for detection and ranging of gas concentrations in a premixed methane flame. Some preliminary tests in a large 12-MW circulating bed boiler have also been done. PMID:21068961

  13. Direct numerical simulation of turbulent H2-O2 combustion using reduced chemistry

    NASA Technical Reports Server (NTRS)

    Montgomery, Christopher J.; Kosaly, George; Riley, James J.

    1993-01-01

    Results of direct numerical simulations of hydrogen-oxygen combustion using a partial-equilibrium chemistry scheme in constant density, decaying, isotropic turbulence are reported. The simulations qualitatively reproduce many features of experimental results, such as superequilibrium radical species mole fractions, with temperature and major species mole fractions closer to chemical equilibrium. It was also observed that the peak reaction rates occur in narrow zones where the stoichiometric surface intersects regions of high scalar dissipation, as might be expected for combustion conditions close to chemical equilibrium. Another finding was that high OH mole fraction correspond more closely to the stoichiometric surface than to areas of high reaction rate for conditions of the simulations. Simulation results were compared to predictions of the Conditional Moment Closure model. This model was found to give good results for all quantities of interest when the conditionally averaged scalar dissipation was used in the prediction. When the nonconditioned average dissipation was used, the predictions compared well to the simulations for most of the species and temperature, but not for the reaction rate. The comparison would be expected to improve for higher Reynolds number flows, however.

  14. Combustion efficiency and hydrocarbon emissions from charcoal production kilns in the tropics

    SciTech Connect

    Ward, D.E.; Hao, W.M.; Babbitt, R.E.

    1995-12-01

    Charcoal is one of the major energy resources in tropical countries. We investigate the combustion processes in charcoal production kilns in Zambia and Brazil. The Zambian kilns were made of earth and there was sufficient air for combustion inside the kilns. The Brazilian kilns were made of bricks which limited the available oxygen. The combustion efficiency and the concentrations of CO{sub 2}, CO, CH{sub 4}, C{sub 2}-C{sub 6} alkanes and alkenes, and aromatic compounds produced were monitored throughout the combustion processes. The contributions of charcoal production processes to the atmospheric sources of these gases were estimated. The strategies for improving charcoal yield and reducing emissions of carbon-containing compounds are discussed.

  15. KINETIC MODELING OF NOX FORMATION AND DESTRUCTION AND COMBUSTIBLES BURNOUT

    EPA Science Inventory

    The report describes a model of the gas-phase chemistry involved in the combustion of simple hydrocarbon fuels and the interconversion of fixed nitrogen species. One focus of the work was on modeling the chemistry involved in reburning and other advanced NOx control strategies. A...

  16. Physics and chemistry of the influence of excited molecules on combustion enhancement

    PubMed Central

    Starik, A. M.; Loukhovitski, B. I.; Sharipov, A. S.; Titova, N. S

    2015-01-01

    The paper addresses detailed analysis of kinetic processes in the H2−O2, CO−O2 and CH4−O2-reactive systems upon the presence of singlet oxygen molecules O2(a1Δg) and and the influence of the activation of oxygen molecules in electric discharge on the acceleration of ignition in the H2−O2 and CH4−O2 mixtures. The possibility of the intensification of CO oxidation due to excitation of O2 and N2 molecule vibrations and generation of singlet oxygen molecules is also considered. It is shown that the effect of accelerating the ignition strongly depends on the reduced electric field and, as a consequence, on the composition of discharge plasma as well as on the features of chain mechanism development in oxy-fuel systems. It is revealed that the most effective approach for the intensification of CO oxidation both in the moist air and in the products of hydrocarbon combustion in air is the generation of O2(a1Δg) molecules by electric discharge. Computations showed that the presence of 1% O2(a1Δg) in the total oxygen allowed one to convert CO to CO2 even at the temperature T=850–900 K in the time of 10−2 s. The excitation of O2 and N2 molecule vibrations is less effective for such a conversion. PMID:26170425

  17. Physics and chemistry of the influence of excited molecules on combustion enhancement.

    PubMed

    Starik, A M; Loukhovitski, B I; Sharipov, A S; Titova, N S

    2015-08-13

    The paper addresses detailed analysis of kinetic processes in the H(2)-O(2), CO-O(2) and CH(4)-O(2)-reactive systems upon the presence of singlet oxygen molecules O(2)(a(1)Δg) and [Formula: see text] and the influence of the activation of oxygen molecules in electric discharge on the acceleration of ignition in the H(2)-O(2) and CH(4)-O(2) mixtures. The possibility of the intensification of CO oxidation due to excitation of O(2) and N(2) molecule vibrations and generation of singlet oxygen molecules is also considered. It is shown that the effect of accelerating the ignition strongly depends on the reduced electric field and, as a consequence, on the composition of discharge plasma as well as on the features of chain mechanism development in oxy-fuel systems. It is revealed that the most effective approach for the intensification of CO oxidation both in the moist air and in the products of hydrocarbon combustion in air is the generation of O(2)(a(1)Δg) molecules by electric discharge. Computations showed that the presence of 1% O(2)(a(1)Δg) in the total oxygen allowed one to convert CO to CO(2) even at the temperature T=850-900 K in the time of 10(-2) s. The excitation of O(2) and N(2) molecule vibrations is less effective for such a conversion. PMID:26170425

  18. Plasma-Enhanced Combustion of Hydrocarbon Fuels and Fuel Blends Using Nanosecond Pulsed Discharges

    SciTech Connect

    Cappelli, Mark; Mungal, M Godfrey

    2014-10-28

    This project had as its goals the study of fundamental physical and chemical processes relevant to the sustained premixed and non-premixed jet ignition/combustion of low grade fuels or fuels under adverse flow conditions using non-equilibrium pulsed nanosecond discharges.

  19. Photochemistry of Saturn's Atmosphere. 1; Hydrocarbon Chemistry and Comparisons with ISO Observations

    NASA Technical Reports Server (NTRS)

    Moses, Julianne I.; Bezard, Bruno; Lellouch, Emmanuel; Gladstone, G. Randall; Feuchtgruber, Helmut; Allen, Mark

    2000-01-01

    To investigate the details of hydrocarbon photochemistry on Saturn, we have developed a one-dimensional diurnally averaged model that couples hydrocarbon and oxygen photochemistry, molecular and eddy diffusion, radiative transfer, and condensation. The model results are compared with observations from the Infrared Space Observatory (ISO) to place tighter constraints on molecular abundances, to better define Saturn's eddy diffusion coefficient profile, and to identify important chemical schemes that control the abundances of the observable hydrocarbons in Saturn's upper atmosphere. From the ISO observations, we determine that the column 12 densities of CH3, CH3C2H, and C4H2 above 10 mbar are 4 (sup +2) (sub -1.5) x 10 (exp 13) cm (sup -2), (1.1 plus or minus 0.3) x 10 (exp 15) cm (exp -2), and (1.2 plus or minus 0.3) x 10 (exp 14) cm (sup -2), respectively. The observed ISO emission features also indicate C2H2 mixing ratios of 1.2 (sup +0.9) (sub -0.6) x 10 (exp -6) at 0.3 mbar and (2.7 plus or minus 0.8) x 10 (exp -7) at 1.4 mbar, and a C2H6 mixing ratio of (9 plus or minus 2.5) x 10 (exp -6) at 0.5 mbar. Upper limits are provided for C2H4, CH2CCH2, C3H8, and C6H2 sensitivity of the model results to variations in the eddy diffusion coefficient profile, the solar flux, the CH4 photolysis branching ratios, the atomic hydrogen influx, and key reaction rates are discussed in detail. We find that C4H2 and CH3C2H are particularly good tracers of important chemical processes and physical conditions in Saturn's upper atmosphere, and C2H6 is a good tracer of the eddy diffusion coefficient in Saturn's lower stratosphere. The eddy diffusion coefficient must be smaller than approximately 3 x 10 (exp 4) sq cm s (sup -1) at pressures greater than 1 mbar in order to reproduce the C2H6 abundance inferred from ISO observations. The eddy diffusion coefficients in the upper stratosphere could be constrained by observations of CH3 radicals if the low-temperature chemistry of CH3 were

  20. Combustion chemistry and flame structure of furan group biofuels using molecular-beam mass spectrometry and gas chromatography – Part I: Furan

    PubMed Central

    Liu, Dong; Togbé, Casimir; Tran, Luc-Sy; Felsmann, Daniel; Oßwald, Patrick; Nau, Patrick; Koppmann, Julia; Lackner, Alexander; Glaude, Pierre-Alexandre; Sirjean, Baptiste; Fournet, René; Battin-Leclerc, Frédérique; Kohse-Höinghaus, Katharina

    2013-01-01

    Fuels of the furan family, i.e. furan itself, 2-methylfuran (MF), and 2,5-dimethylfuran (DMF) are being proposed as alternatives to hydrocarbon fuels and are potentially accessible from cellulosic biomass. While some experiments and modeling results are becoming available for each of these fuels, a comprehensive experimental and modeling analysis of the three fuels under the same conditions, simulated using the same chemical reaction model, has – to the best of our knowledge – not been attempted before. The present series of three papers, detailing the results obtained in flat flames for each of the three fuels separately, reports experimental data and explores their combustion chemistry using kinetic modeling. The first part of this series focuses on the chemistry of low-pressure furan flames. Two laminar premixed low-pressure (20 and 40 mbar) flat argon-diluted (50%) flames of furan were studied at two equivalence ratios (φ=1.0 and 1.7) using an analytical combination of high-resolution electron-ionization molecular-beam mass spectrometry (EI-MBMS) in Bielefeld and gas chromatography (GC) in Nancy. The time-of-flight MBMS with its high mass resolution enables the detection of both stable and reactive species, while the gas chromatograph permits the separation of isomers. Mole fractions of reactants, products, and stable and radical intermediates were measured as a function of the distance to the burner. A single kinetic model was used to predict the flame structure of the three fuels: furan (in this paper), 2-methylfuran (in Part II), and 2,5-dimethylfuran (in Part III). A refined sub-mechanism for furan combustion, based on the work of Tian et al. [Combustion and Flame 158 (2011) 756-773] was developed which was then compared to the present experimental results. Overall, the agreement is encouraging. The main reaction pathways involved in furan combustion were delineated computing the rates of formation and consumption of all species. It is seen that the

  1. Combustion chemistry and flame structure of furan group biofuels using molecular-beam mass spectrometry and gas chromatography - Part I: Furan.

    PubMed

    Liu, Dong; Togbé, Casimir; Tran, Luc-Sy; Felsmann, Daniel; Oßwald, Patrick; Nau, Patrick; Koppmann, Julia; Lackner, Alexander; Glaude, Pierre-Alexandre; Sirjean, Baptiste; Fournet, René; Battin-Leclerc, Frédérique; Kohse-Höinghaus, Katharina

    2014-03-01

    Fuels of the furan family, i.e. furan itself, 2-methylfuran (MF), and 2,5-dimethylfuran (DMF) are being proposed as alternatives to hydrocarbon fuels and are potentially accessible from cellulosic biomass. While some experiments and modeling results are becoming available for each of these fuels, a comprehensive experimental and modeling analysis of the three fuels under the same conditions, simulated using the same chemical reaction model, has - to the best of our knowledge - not been attempted before. The present series of three papers, detailing the results obtained in flat flames for each of the three fuels separately, reports experimental data and explores their combustion chemistry using kinetic modeling. The first part of this series focuses on the chemistry of low-pressure furan flames. Two laminar premixed low-pressure (20 and 40 mbar) flat argon-diluted (50%) flames of furan were studied at two equivalence ratios (φ=1.0 and 1.7) using an analytical combination of high-resolution electron-ionization molecular-beam mass spectrometry (EI-MBMS) in Bielefeld and gas chromatography (GC) in Nancy. The time-of-flight MBMS with its high mass resolution enables the detection of both stable and reactive species, while the gas chromatograph permits the separation of isomers. Mole fractions of reactants, products, and stable and radical intermediates were measured as a function of the distance to the burner. A single kinetic model was used to predict the flame structure of the three fuels: furan (in this paper), 2-methylfuran (in Part II), and 2,5-dimethylfuran (in Part III). A refined sub-mechanism for furan combustion, based on the work of Tian et al. [Combustion and Flame 158 (2011) 756-773] was developed which was then compared to the present experimental results. Overall, the agreement is encouraging. The main reaction pathways involved in furan combustion were delineated computing the rates of formation and consumption of all species. It is seen that the

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

    SciTech Connect

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

    2010-12-12

    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 (e.g., 1-, 2-, iso- and tert-butanol). The proposed model includes detailed high temperature and low temperature reaction pathways. In this study, the primary experimental validation target for the model is premixed flat low-pressure flame species profiles obtained using molecular beam mass spectrometry (MBMS). The model is also validated against previously published data for premixed flame velocity and n-butanol rapid compression machine and shock tube ignition delay. The agreement with these data sets is reasonably good. The dominant reaction pathways at the various pressures and temperatures studied are elucidated. At low temperature conditions, we found that the reaction of alphahydroxybutyl with O{sub 2} was important in controlling the reactivity of the system, and for correctly predicting C{sub 4} aldehyde profiles in low pressure premixed flames. Enol-keto isomerization reactions assisted by HO{sub 2} were also found to be important in converting enols to aldehydes and ketones in the low pressure premixed flames. In the paper, we describe how the structural features of the four different butanol isomers lead to differences in the combustion properties of each isomer.

  3. Dispersion modeling of polycyclic aromatic hydrocarbons from combustion of biomass and fossil fuels and production of coke in Tianjin, China

    SciTech Connect

    Shu Tao; Xinrong Li; Yu Yang; Raymond M. Coveney, Jr.; Xiaoxia Lu; Haitao Chen; Weiran Shen

    2006-08-01

    A USEPA procedure, ISCLT3 (Industrial Source Complex Long-Term), was applied to model the spatial distribution of polycyclic aromatic hydrocarbons (PAHs) emitted from various sources including coal, petroleum, natural gas, and biomass into the atmosphere of Tianjin, China. Benzo(a)pyrene equivalent concentrations (BaPeq) were calculated for risk assessment. Model results were provisionally validated for concentrations and profiles based on the observed data at two monitoring stations. The dominant emission sources in the area were domestic coal combustion, coke production, and biomass burning. Mainly because of the difference in the emission heights, the contributions of various sources to the average concentrations at receptors differ from proportions emitted. The shares of domestic coal increased from {approximately} 43% at the sources to 56% at the receptors, while the contributions of coking industry decreased from {approximately} 23% at the sources to 7% at the receptors. The spatial distributions of gaseous and particulate PAHs were similar, with higher concentrations occurring within urban districts because of domestic coal combustion. With relatively smaller contributions, the other minor sources had limited influences on the overall spatial distribution. The calculated average BaPeq value in air was 2.54 {+-} 2.87 ng/m{sup 3} on an annual basis. Although only 2.3% of the area in Tianjin exceeded the national standard of 10 ng/m{sup 3}, 41% of the entire population lives within this area. 37 refs., 9 figs.

  4. The chemistry and spatial distribution of small hydrocarbons in UV-irradiated molecular clouds: the Orion Bar PDR

    NASA Astrophysics Data System (ADS)

    Cuadrado, S.; Goicoechea, J. R.; Pilleri, P.; Cernicharo, J.; Fuente, A.; Joblin, C.

    2015-03-01

    Context. Carbon chemistry plays a pivotal role in the interstellar medium (ISM) but even the synthesis of the simplest hydrocarbons and how they relate to polycyclic aromatic hydrocarbons (PAHs) and grains is not well understood. Aims: We study the spatial distribution and chemistry of small hydrocarbons in the Orion Bar photodissociation region (PDR), a prototypical environment in which to investigate molecular gas irradiated by strong UV fields. Methods: We used the IRAM 30 m telescope to carry out a millimetre line survey towards the Orion Bar edge, complemented with ~2' × 2' maps of the C2H and c-C3H2 emission. We analyse the excitation of the detected hydrocarbons and constrain the physical conditions of the emitting regions with non-LTE radiative transfer models. We compare the inferred column densities with updated gas-phase photochemical models including 13CCH and C13CH isotopomer fractionation. Results: Approximately 40% of the lines in the survey arise from hydrocarbons (C2H, C4H, c-C3H2, c-C3H, C13CH, 13CCH, l-C3H, and l-H2C3 in decreasing order of abundance). We detect new lines from l-C3H+ and improve its rotational spectroscopic constants. Anions or deuterated hydrocarbons are not detected, but we provide accurate upper limit abundances: [C2D]/[C2H] < 0.2%, [C2H-]/[C2H] < 0.007%, and [C4H-]/[C4H] < 0.05%. Conclusions: Our models can reasonably match the observed column densities of most hydrocarbons (within factors of <3). Since the observed spatial distribution of the C2H and c-C3H2 emission is similar but does not follow the PAH emission, we conclude that, in high UV-flux PDRs, photodestruction of PAHs is not a necessary requirement to explain the observed abundances of the smallest hydrocarbons. Instead, gas-phase endothermic reactions (or with barriers) between C+, radicals, and H2 enhance the formation of simple hydrocarbons. Observations and models suggest that the [C2H]/[c-C3H2] ratio (~32 at the PDR edge) decreases with the UV field

  5. Probing combustion chemistry in a miniature shock tube with synchrotron VUV photo ionization mass spectrometry.

    PubMed

    Lynch, Patrick T; Troy, Tyler P; Ahmed, Musahid; Tranter, Robert S

    2015-02-17

    Tunable synchrotron-sourced photoionization time-of-flight mass spectrometry (PI-TOF-MS) is an important technique in combustion chemistry, complementing lab-scale electron impact and laser photoionization studies for a wide variety of reactors, typically at low pressure. For high-temperature and high-pressure chemical kinetics studies, the shock tube is the reactor of choice. Extending the benefits of shock tube/TOF-MS research to include synchrotron sourced PI-TOF-MS required a radical reconception of the shock tube. An automated, miniature, high-repetition-rate shock tube was developed and can be used to study high-pressure reactive systems (T > 600 K, P < 100 bar) behind reflected shock waves. In this paper, we present results of a PI-TOF-MS study at the Advanced Light Source at Lawrence Berkeley National Laboratory. Dimethyl ether pyrolysis (2% CH3OCH3/Ar) was observed behind the reflected shock (1400 < T5 < 1700 K, 3 < P5 < 16 bar) with ionization energies between 10 and 13 eV. Individual experiments have extremely low signal levels. However, product species and radical intermediates are well-resolved when averaging over hundreds of shots, which is ordinarily impractical in conventional shock tube studies. The signal levels attained and data throughput rates with this technique are comparable to those with other synchrotron-based PI-TOF-MS reactors, and it is anticipated that this high pressure technique will greatly complement those lower pressure techniques. PMID:25594229

  6. Polycyclic aromatic hydrocarbon and particulate emissions from two-stage combustion of polystyrene: the effect of the primary furnace temperature.

    PubMed

    Wang, J; Levendis, Y A; Richter, H; Howard, J B; Carlson, J

    2001-09-01

    A study is presented on laboratory-scale combustion of polystyrene (PS) to identify staged-combustion conditions that minimize emissions. Batch combustion of shredded PS was conducted in fixed beds placed in a bench-scale electrically heated horizontal muffle furnace. In most cases, combustion of the samples occurred by forming gaseous diffusion flames in atmospheric pressure air. The combustion effluent was mixed with additional air, and it was channeled to a second muffle furnace (afterburner) placed in series. Further reactions took place in the secondary furnace at a residence time of 0.7 s. The gas temperature of the primary furnace was varied in the range of 500-1,000 degrees C, while that of the secondary furnace was kept fixed at 1,000 degrees C. Sampling for CO, CO2, O2, soot, and unburned hydrocarbon emissions (volatile and semivolatile, by GC-MS) was performed at the exits of the two furnaces. Results showed that the temperature of the primary furnace, where PS gasifies, is of paramount importance to the formation and subsequent emissions of organic species and soot. Atthe lowesttemperatures explored, mostly styrene oligomers were identified at the outlet of the primary furnace, but they did not survive the treatment in the secondary furnace. The formation and emission of polycyclic aromatic hydrocarbons (PAH) and soot were suppressed. As the temperature in the first furnace was raised, increasing amounts of a wide range of both unsubstituted and substituted PAH containing up to at least seven condensed aromatic rings were detected. A similar trend was observed for total particulate yields. The secondary furnace treatment reduced the yields of total PAH, but it had an ambiguous effect on individual species. While most low molecular mass PAH were reduced in the secondary furnace, concentrations of some larger PAH increased under certain conditions. Thus, care in the selection of operating conditions of both the primary furnace (gasifier/ burner) and the

  7. Comprehensive Mechanisms for Combustion Chemistry: An Experimental and Numerical Study with Emphasis on Applied Sensitivity Analysis

    SciTech Connect

    Dryer, Frederick L.

    2009-04-10

    This project was an integrated experimental/numerical effort to study pyrolysis and oxidation reactions and mechanisms for small-molecule hydrocarbon structures under conditions representative of combustion environments. The experimental aspects of the work were conducted in large-diameter flow reactors, at 0.3 to 18 atm pressure, 500 to 1100 K temperature, and 10-2 to 2 seconds reaction time. Experiments were also conducted to determine reference laminar flame speeds using a premixed laminar stagnation flame experiment and particle image velocimetry, as well as pressurized bomb experiments. Flow reactor data for oxidation experiments include: (1)adiabatic/isothermal species time-histories of a reaction under fixed initial pressure, temperature, and composition; to determine the species present after a fixed reaction time, initial pressure; (2)species distributions with varying initial reaction temperature; (3)perturbations of a well-defined reaction systems (e.g. CO/H2/O2 or H2/O2)by the addition of small amounts of an additive species. Radical scavenging techniques are applied to determine unimolecular decomposition rates from pyrolysis experiments. Laminar flame speed measurements are determined as a function of equivalence ratio, dilution, and unburned gas temperature at 1 atm pressure. Hierarchical, comprehensive mechanistic construction methods were applied to develop detailed kinetic mechanisms which describe the measurements and literature kinetic data. Modeling using well-defined and validated mechanisms for the CO/H2/Oxidant systems and perturbations of oxidation experiments by small amounts of additives were also used to derive absolute reaction rates and to investigate the compatibility of published elementary kinetic and thermochemical information. Numerical tools were developed and applied to assess the importance of individual elementary reactions to the predictive performance of the

  8. Symposium (International) on Combustion, 20th, University of Michigan, Ann Arbor, MI, August 12-17, 1984, Proceedings

    NASA Technical Reports Server (NTRS)

    1985-01-01

    The present conference on combustion phenomena considers topics in automotive engine combustion, turbulent reacting flows, the modeling of practical combustion systems, reaction kinetics, combustion-generated particulates, combustion diagnostics, coal combustion process characteristics, fire-related phenomena, explosion/detonation phenomena, spray combustion, ignition/extinction, laminar flames, pollutant formation processes, practical combustor devices, and rocket propellant combustion. Attention is given to the contributions of combustion science to piston engine design, modeling and measurement techniques for turbulent combustion, the specific effects of energy, collisions, and transport processes in combustion chemistry kinetics, the formation of large molecules, particulates and ions in premixed hydrocarbon flames, the application of laser diagnostics to combustion systems, spark ignition energies for dust-air mixtures, the controlling mechanisms of flow-assisted flame spread, the ignition and combustion of coal-water slurries, spontaneous ignition of methane, turbulent and accelerating dust flames, and the temperature sensitivity of double base propellants.

  9. Calculated equilibrium yields of C sub 60 from hydrocarbon pyrolysis and combustion

    SciTech Connect

    McKinnon, J.T. )

    1991-10-31

    The equilibrium yield of Buckminsterfullerene, C{sub 60}, has been computed for the pyrolysis and oxidation of a hydrocarbon source using a free-energy-minimization computer code as a function of temperature, pressure, and element ratios. High C{sub 60} yields are favored by low pressure and high C/H ratios and low oxygen concentrations. A temperature window exists in which fullerene yields are favored between 2,200 and 2,600 K. The computed yields are extremely sensitive to the value used for the C{sub 60} heat of formation and are fairly sensitive to the vibrational frequencies of the molecule.

  10. Sampling and analysis of hydrocarbons in combustion gases. Annual report, October 1979-September 1980

    SciTech Connect

    Johnson, I.; Myles, K.M.; Siczek, A.A.

    1981-04-01

    The purpose of these studies is to develop a method for the chemical analysis of ultratrace levels of polycyclic organic compounds in the flue gases from fluidized-bed combustors. Methods which have the potential for real time analysis have been studied. Two methods, double mass spectrometry and laser ionization mass spectrometry, appear to be promising. A brief review of current analytical methods has been made. A brief examination of fly ash from fluidized-bed combustion revealed no carcinogenic species although samples collected during fluidized-bed combustor startup were found to be mutagenic.

  11. FUNDAMENTAL COMBUSTION RESEARCH APPLIED TO POLLUTION FORMATION. VOLUME 2B. PHYSICS AND CHEMISTRY OF TWO-PHASE SYSTEMS: DEVOLATILIZATION AND VOLATILE REACTIONS

    EPA Science Inventory

    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 parameter...

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

    PubMed Central

    2013-01-01

    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%. PMID:23289764

  13. Combustion efficiency and altitude operational limits of three liquid hydrocarbon fuels having high volumetric energy content in a J33 single combustor

    NASA Technical Reports Server (NTRS)

    Stricker, Edward G

    1950-01-01

    Combustion efficiency and altitude operational limits were determined in a J33 single combustor for AN-F-58 fuel and three liquid hydrocarbon fuels having high volumetric energy content (decalin, tetralin, and monomethylnaphthalene) at simulated altitude and combustor inlet-air conditions. At the conditions investigated, the combustion efficiency for the four fuels generally decreased with an increase in volumetric energy content. The altitude operational limits for decalin and tetralin fuels were higher than for AN-F-58 fuel; monomethylnaphthalene fuel gave the lowest altitude operational limit.

  14. Combustion rate limits of hydrogen plus hydrocarbon fuel: Air diffusion flames from an opposed jet burner technique

    NASA Technical Reports Server (NTRS)

    Pellett, Gerald L.; Guerra, Rosemary; Wilson, Lloyd G.; Reeves, Ronald N.; Northam, G. Burton

    1987-01-01

    Combustion of H2/hydrocarbon (HC) fuel mixtures may be considered in certain volume-limited supersonic airbreathing propulsion applications. Effects of HC addition to H2 were evaluated, using a recent argon-bathed, coaxial, tubular opposed jet burner (OJB) technique to measure the extinction limits of counterflow diffusion flames. The OJB flames were formed by a laminar jet of (N2 and/or HC)-diluted H2 mixture opposed by a similar jet of air at ambient conditions. The OJB data, derived from respective binary mixtures of H2 and methane, ethylene, or propane HCs, were used to characterize BLOWOFF and RESTORE. BLOWOFF is a sudden breaking of the dish-shaped OJB flame to a stable torus or ring shape, and RESTORE marks sudden restoration of the central flame by radial inward flame propagation. BLOWOFF is a measure of kinetically-limited flame reactivity/speed under highly stretched, but relatively ideal impingement flow conditions. RESTORE measures inward radial flame propagation rate, which is sensitive to ignition processes in the cool central core. It is concluded that relatively small molar amounts of added HC greatly reduce the reactivity characteristics of counterflow hydrogen-air diffusion flames, for ambient initial conditions.

  15. Speciated hydrocarbon and carbon monoxide emissions from an internal combustion engine operating on methyl tertiary butyl ether-containing fuels.

    PubMed

    Poulopoulos, S G; Philippopoulos, C J

    2001-07-01

    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 unburned hydrocarbons, carbon monoxide, methane, hexane, ethylene, acetaldehyde, acetone, 2-propanol, benzene, toluene, 1,3-butadiene, acetic acid, and MTBE were measured at each engine operating condition. As concerns the total HC emissions, the use of MTBE was beneficial from 1.90 to 3.81 HP, which were by far the most polluting conditions. Moreover, CO emissions in tailpipe exhaust were decreased in the whole operation range with increasing MTBE in the fuel. The greatest advantage of MTBE addition to gasoline was the decrease in ethylene, acetaldehyde, benzene, toluene, and acetic acid emissions in engine exhaust, especially when MTBE content in the fuel was increased to 11% w/w. In tailpipe exhaust, the catalyst operation diminished the observed differences. Ethylene, methane, and acetaldehyde were the main compounds present in exhaust gases. Ethylene was easily oxidized over the catalyst, while acetaldehyde and methane were quite resistant to oxidation. PMID:15658218

  16. Symposium (International) on Combustion, 19th, Technion Israel Institute of Technology, Haifa, Israel, August 8-13, 1982, Proceedings

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Topics discussed are related to elementary reactions, reaction mechanisms and modeling, laminar flames, flame chemistry, turbulent reacting shear flows, turbulent premixed flames, turbulent combustion measurements, continuous combustors, detonation, detonation and explosion, heterogeneous detonation, propellant combustion, fire-ignition and thermal degradation, fire-flame spread and burning, fire-modeling, spray combustion, and droplet combustion. Coal combustion kinetics and mechanisms are considered along with coal combustion mechanisms and pyrolysis, coal combustion techniques, NOx in coal combustion, gaseous pollutants, soot and PAH, soot and inorganic pollutants, I.C. engine combustion, and ignition and extinction. Attention is given to intricate paths and simple steps in chemical kinetics and combustion, the formation of polycyclic aromatic hydrocarbons by combustion, turbulent flame structure and speed in spark ignition engines, and unresolved problems in SOx, NOx, and soot control in combustion.

  17. Combustion performance and heat transfer characterization of LOX/hydrocarbon type propellants, volume 1

    NASA Technical Reports Server (NTRS)

    Michel, R. W.

    1983-01-01

    A program to evaluate liquid oxygen and various hydrocarbon fuel as low cost alternative propellants suitable for future space transportation system applications is discussed. The emphasis of the program is directed toward low earth orbit maneuvering engine and reaction control engine systems. The feasibility of regeneratively cooling an orbit maneuvering thruster was analytically determined over a range of operating conditions from 100 to 1000 psia chamber pressure and 1000 to 10,000-1bF thrust, and specific design points were analyzed in detail for propane, methane, RP-1, ammonia, and ethanol; similar design point studies were performed for a filmcooled reaction control thruster. Heat transfer characteristics of propate were experimentally evaluated in heated tube tests. Forced convection heat transfer coefficients were determined over the range of fluid conditions encompassed by 450 to 1800 psia, -250 to +250 F, and 50 to 150 ft/sec, with wall temperatures from ambient to 1200 F. Seventy-seven hot firing tests were conducted with LOX/propane and LOC/ethanol, for a total duration of nearly 1400 seconds, using both heat sink and water-cooled calorimetric chambers.

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

    NASA Technical Reports Server (NTRS)

    Bittker, D. A.; Wolfbrandt, G.

    1981-01-01

    How the emissions of nitrogen oxides and carbon monoxide are affected by: (1) the decreased hydrogen content and (2) the increased organic nitrogen content of coal derived fuels is investigated. Previous CRT experimental work in a two stage flame tube has shown the effectiveness of rich lean two stage combustion in reducing fuel nitrogen conversion to nitrogen oxides. Previous theoretical work gave preliminary indications that emissions trends from the flame tube experiment could be predicted by a two stage, well stirred reactor combustor model using a detailed chemical mechanism for propane oxidation and nitrogen oxide formation. Additional computations are reported and comparisons with experimental results for two additional fuels and a wide range of operating conditions are given. Fuels used in the modeling are pure propane, a propane toluene mixture and pure toluene. These give hydrogen contents 18, 11 and 9 percent by weight, respectively. Fuel bound nitrogen contents of 0.5 and 1.0 percent were used. Results are presented for oxides of nitrogen and also carbon monoxide concentrations as a function of primary equivalence ratio, hydrogen content and fuel bound nitrogen content.

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

    ERIC Educational Resources Information Center

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

    2006-01-01

    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…

  20. An experimental and numerical investigation on hydrogen-hydrocarbon composite fuel combustion

    NASA Astrophysics Data System (ADS)

    Choudhuri, Ahsan Reza

    An experimental and numerical study on the combustion characteristics of turbulent diffusion flames of natural gas-hydrogen composite fuel is presented. Three mixtures (90--10%, 80--20% and 65--35% by volume) of natural gas and hydrogen were used. The results are compared with the combustion characteristics of a pure natural gas flame. The following parameters were measured: (i) flame stability (blowout velocity, and lift-off height at blowout condition), (ii) temperature field (radial profiles at three axial locations), (iii) composition profiles of stable species (CO 2, CO, NO, O2), (iv) composition profiles of intermediate species (OH, CH, H and O), and (v) visible flame length, flame radiation, emission indices and volumetric soot concentration. To study the flame stability five burners of 1mm, 2.3mm, 3.8mm and 4.5mm ID were used. Direct video photography, Schlieren imaging and acetone Planar Laser Induced Fluorescence (PLIF) imaging were used for flame stability and mixing study. For stable species concentration measurements, an uncooled quartz glass probe with chemilumenesce and infrared analyzers were used. Laser Induced Fluorescence (LIF) and Planar Laser Induced Fluorescence (PLIF) technique were used to measure radical concentrations. A combined LIF-Raman Spectroscopic procedure was carried out to quantify the LIF signals. The following parameters were analyzed numerically: (i) cold jet mixing (axial and radial velocity, turbulent intensity, turbulent kinetic energy and local equivalence ratio), (ii) flame temperature, (iii) stable species (CO2, CO, NO, O2) and (iv) intermediate species concentrations (OH, CH, CN, H, and O). For the numerical computation, Favre-averaged Navier-Stokes equations with two-step reaction kinetics and the standard k-epsilon turbulence model were used. The fuel jet exit Reynolds number was kept constant at 8700 for flame structure measurements, computation, and measurements of global characteristics. The corresponding flame

  1. Improved Recovery Boiler Performance Through Control of Combustion, Sulfur, and Alkali Chemistry

    SciTech Connect

    Baxter, Larry L.

    2008-06-09

    This project involved the following objectives: 1. Determine black liquor drying and devolatilization elemental and total mass release rates and yields. 2. Develop a public domain physical/chemical kinetic model of black liquor drop combustion, including new information on drying and devolatilization. 3. Determine mechanisms and rates of sulfur scavenging in recover boilers. 4. Develop non-ideal, public-domain thermochemistry models for alkali salts appropriate for recovery boilers 5. Develop data and a one-dimensional model of a char bed in a recovery boiler. 6. Implement all of the above in comprehensive combustion code and validate effects on boiler performance. 7. Perform gasification modeling in support of INEL and commercial customers. The major accomplishments of this project corresponding to these objectives are as follows: 1. Original data for black liquor and biomass data demonstrate dependencies of particle reactions on particle size, liquor type, gas temperature, and gas composition. A comprehensive particle submodel and corresponding data developed during this project predicts particle drying (including both free and chemisorbed moisture), devolatilization, heterogeneous char oxidation, char-smelt reactions, and smelt oxidation. Data and model predictions agree, without adjustment of parameters, within their respective errors. The work performed under these tasks substantially exceeded the original objectives. 2. A separate model for sulfur scavenging and fume formation in a recovery boiler demonstrated strong dependence on both in-boiler mixing and chemistry. In particular, accurate fume particle size predictions, as determined from both laboratory and field measurements, depend on gas mixing effects in the boilers that lead to substantial particle agglomeration. Sulfur scavenging was quantitatively predicted while particle size required one empirical mixing factor to match data. 3. Condensed-phase thermochemistry algorithms were developed for salt

  2. CHEMISTRY OF SECONDARY ORGANIC AEROSOL FORMATION FROM THE OXIDATION OF AROMATIC HYDROCARBONS

    EPA Science Inventory

    The experimental data obtained in this project will include reaction rate constants, product branching ratios, and yields of gas-phase and particle-phase products and SOA from OH radical-initiated reactions of aromatic hydrocarbons. These data will be used by atmospheric model...

  3. Computational Interstellar Chemistry

    NASA Astrophysics Data System (ADS)

    Hirata, So; Fan, Peng-Dong; Head-Gordon, Martin; Kamiya, Muneaki; Keçeli, Murat; Lee, Timothy J.; Shiozaki, Toru; Szczepanski, Jan; Vala, Martin; Valeev, Edward F.; Yagi, Kiyoshi

    Computational applications of electronic and vibrational many-body theories are increasingly indispensable in interpreting and, in some instances, predicting the spectra of gas-phase molecular species of importance in interstellar chemistry as well as in atmospheric and combustion chemistry. This chapter briefly reviews our methodological developments of electronic and vibrational many-body theories that are particularly useful for these gas-phase molecular problems. Their applications to anharmonic vibrational frequencies of triatomic and tetratomic interstellar molecules and to electronic absorption spectra of the radical ions of polycyclic aromatic hydrocarbons, which are ubiquitous in the interstellar medium, are also discussed.

  4. Formation of Polycyclic Aromatic Hydrocarbons and Nitrogen Containing Polycyclic Aromatic Compounds in Titan's Atmosphere, the Interstellar Medium and Combustion

    NASA Astrophysics Data System (ADS)

    Landera, Alexander

    2013-12-01

    Several different mechanisms leading to the formation of (substituted) naphthalene and azanaphthalenes were examined using theoretical quantum chemical calculations. As a result, a series of novel synthetic routes to Polycyclic Aromatic Hydrocarbons (PAHs) and Nitrogen Containing Polycyclic Aromatic Compounds (N-PACs) have been proposed. On Earth, these aromatic compounds originate from incomplete combustion and are released into our environment, where they are known to be major pollutants, often with carcinogenic properties. In the atmosphere of a Saturn's moon Titan, these PAH and N-PACs are believed to play a critical role in organic haze formation, as well as acting as chemical precursors to biologically relevant molecules. The theoretical calculations were performed by employing the ab initio G3(MP2,CC)/B3LYP/6-311G** method to effectively probe the Potential Energy Surfaces (PES) relevant to the PAH and N-PAC formation. Following the construction of the PES, Rice-Ramsperger-Kassel-Markus (RRKM) theory was used to evaluate all unimolecular rate constants as a function of collision energy under single-collision conditions. Branching ratios were then evaluated by solving phenomenological rate expressions for the various product concentrations. The most viable pathways to PAH and N-PAC formation were found to be those where the initial attack by the ethynyl (C2H) or cyano (CN) radical toward a unsaturated hydrocarbon molecule led to the formation of an intermediate which could not effectively lose a hydrogen atom. It is not until ring cyclization has occurred, that hydrogen elimination leads to a closed shell product. By quenching the possibility of the initial hydrogen atom elimination, one of the most competitive processes preventing the PAH or N-PAC formation was avoided, and the PAH or N-PAC formation was allowed to proceed. It is concluded that these considerations should be taken into account when attempting to explore any other potential routes towards

  5. Abiotic Organic Chemistry of the Terrestrial Deep Subsurface: Isotopic Constraints on Hydrocarbon Formation

    NASA Astrophysics Data System (ADS)

    Sherwood Lollar, B.; McCollom, T. M.; Seewald, J. S.; Lacrampe-Couloume, G.

    2008-12-01

    In serpentinized terrains in both marine and terrestrial subsurface, recent attention has focused on H2 and hydrocarbon gases - on their potential production by abiogenic processes of water-rock interaction; the possibility of their use by deep microbial communities as substrates for life; and on the relevance of such subsurface analogs for the origin of life on earth or elsewhere in the solar system. In deep subsurface Precambrian Shield rocks in South Africa, Canada and Finland, H2, methane and higher hydrocarbon gases have been identified at depths of 1-4 km. While some sites are dominated by gases produced by microbial methanogenesis, the deepest, most ancient fracture waters with residence times on the order of tens of millions of years contain hydrocarbon gases with a pattern of carbon isotope depletion in 13C and hydrogen isotope enrichment in 2H between methane and ethane consistent with abiogenic polymerization1. More recently, the carbon and hydrogen isotope variation between the higher hydrocarbon homologues have also been demonstrated to fit a simple mass balance model consistent with abiogenic polymerization reactions2. In this study, a series of experiments were performed by heating aqueous solutions at 250°C and 170Mpa under reducing conditions using powdered native Fe as a source of H2 and catalyst, and CO as a carbon source in a flexible cell hydrothermal apparatus. Experiments resulted in rapid generation of methane and higher hydrocarbon products typical of Fischer- Tropsch abiotic organic synthesis. These gases were analyzed for carbon and hydrogen isotopes to verify the polymerization model. Unlike the field samples, the experiments showed a carbon isotope enrichment between methane and ethane - suggesting that the extent of fractionation in the first, most highly fractionating step may vary as a function of different reaction mechanisms or parameters such as catalysts or conversion ratios. For the higher hydrocarbons however, carbon isotope

  6. Photolytic formation of free radicals and their effect on hydrocarbon pyrolysis chemistry in a concentrated solar environment

    SciTech Connect

    Hunjan, M.S.; Mok, W.S.L.; Antal, M.J. Jr. . Dept. of Mechanical Engineering)

    1989-08-01

    High-energy photons present in concentrated sunlight can be used to photolytically dissociate certain vapor-phase compounds known to be sources of free radicals. These free radicals can subsequently initiate or influence pyrolysis reactions involving hydrocarbons. Experiments were conducted in a vapor-phase, tubular flow reactor placed at the focus of a 1-kW arc image furnace, which acted as a source of simulated concentrated sunlight. Experimentally observed rates of acetone photolysis were in close agreement with the values predicted by employing the Beer-Lambert law. By the use of acetone as a photosensitizing agent, the photosensitized pyrolysis chemistry of n-butane, at 350{sup 0}C, was studied. Without photosensitization, no pyrolysis was observed. With photosensitization, a modest (2-4%) conversion of n-butane to butane, hexene, propene, and other hydrocarbons was achieved. Numerical simulations of the photosensitized pyrolysis behavior provided results similar to the experimental observations. The results of numerical simulations at higher temperatures lead the authors to conclude that major photosensitization effects may be observed at temperatures between 400 and 500{sup 0}C.

  7. Fundamentals of Gas Turbine combustion

    NASA Technical Reports Server (NTRS)

    Gerstein, M.

    1979-01-01

    Combustion problems and research recommendations are discussed in the areas of atomization and vaporization, combustion chemistry, combustion dynamics, and combustion modelling. The recommendations considered of highest priority in these areas are presented.

  8. Photolytic formation of free radicals and their effect on hydrocarbon pyrolysis chemistry in a concentrated solar environment: Final report

    SciTech Connect

    Hunjan, M.; Mok, W.S.; Antal, M.J. Jr.

    1987-01-01

    The objective of this research was two-fold: (1) to determine whether uv photons available in a concentrated solar environment can be used as a photolytic source to dissociate vapor phase acetone; and (2) to explore the effects of photolysis on rate and selectivity of free radical reactions. The experiments were conducted in a 1 kW arc image furnace/tubular flow reactor system. The results obtained conclusively showed that acetone readily photodissociates in a 1000 sun environment, leading to the formation of free radicals. It was further observed that Beer-Lambert law can be used to predict the rate of photolysis of acetone. Furthermore, acetone, when used as source of methyl radicals, sensitized the reaction chemistry of alkanes and alkenes at a temperature of 350/sup 0/C. The methyl radicals from photolysis of acetone enhanced the cracking reactions of the alkanes yielding smaller alkanes and alkenes. When the initial hydrocarbon reactant was an alkene, a sensitization of the addition reaction was observed leading to formation of next higher alkene. To gain a theoretical insight into the reaction chemistry of alkanes, a numerical simulation model was developed to study the photosensitized decomposition of n-butane and the simulation results thus obtained were found to be in close agreement with experimental results. 64 refs., 10 figs., 22 tabs.

  9. Program on the combustion chemistry of low- and intermediate-Btu gas mixtures

    SciTech Connect

    Not Available

    1981-11-30

    Low and intermediate Btu (LBTU and IBTU) gas mixtures are essentially mixtures of CO, H/sub 2/ and CH/sub 4/ diluted with nitrogen and CO/sub 2/. Although the combustion properties of these three fuels have been extensively investigated and their individual combustion kinetics are reasonably well established, prediction techniques for applying these gas mixtures remain for the most part empirical. This program has aimed to bring together and apply some of the fundamental combustion parameters to the CO-H/sub 2/-CH/sub 4/ flame system with the hope of reducing some of this empiricism. Four topical reports have resulted from this program. This final report summarizes these reports and other activities undertaken in this program. This program was initiated June 22, 1976 under ERDA Contract No. E(49-18)-2406 and was later continued under DOE/PETC and DOE Contract No. DE-AC22-76ET10653.

  10. Analysis of Absorption Spectra of Polycyclic Aromatic Hydrocarbons in Gaseous- and Particle- Phase Emissions from Peat Fuel Combustion Under Controlled Conditions

    NASA Astrophysics Data System (ADS)

    Connolly, J. I.; Samburova, V.; Moosmüller, H.; Khlystov, A.

    2015-12-01

    Biomass and fossil fuel burning processes emit important organic pollutants called polycyclic aromatic hydrocarbons (PAHs) into the atmosphere. Smoldering combustion of peat is one of the largest contributors (up to 70%) of carbonaceous species and, therefore, it may be one of the main sources of these PAHs. PAHs can be detrimental to health, they are known to be potent mutagens and suspected carcinogens. They may also contribute to solar light absorption as the particles absorb in the blue and near ultraviolet (UV) region of the solar spectrum ("brown carbon" species). There is very little knowledge and large ambiguity regarding the contribution of PAHs to optical properties of organic carbon (OC) emitted from smoldering biomass combustion. This study focuses on quantifying and analyzing PAHs emitted from peat smoldering combustion to gain more knowledge on their optical properties. Five peat fuels collected in different regions of the world (Russia, USA) were burned under controlled conditions (e.g., relative humidity, combustion efficiency, fuel-moisture content) at the Desert Research Institute Biomass Burning facility (Reno, NV, USA). Combustion aerosols collected on TIGF filters followed by XAD resin cartridges were extracted and analyzed for gas-phase (semi-volatile) and particle-phase PAHs. Filter and XAD samples were extracted separately with dichloromethane followed by acetone using Accelerated Solvent Extractor (ACE 300, Dionex). To determine absorption properties, absorption spectra of extracts and standard PAHs were recorded between 190 and 900 nm with a UV/VIS spectrophotometer (PerkinElmer, Lambda 650). This poster will discuss the potential contribution of PAHs to brown carbon emitted from peat combustion and give a brief comparison with absorption spectra from biomass burning aerosols.

  11. Terascale High-Fidelity Simulations of Turbulent Combustion with Detailed Chemistry

    SciTech Connect

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

    2012-08-13

    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.

  12. Terascale High-Fidelity Simulations of Turbulent Combustion with Detailed Chemistry

    SciTech Connect

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

    2009-02-02

    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.

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

    NASA Astrophysics Data System (ADS)

    Weibring, G.; Zellner, R.

    1994-05-01

    . 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.

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

    SciTech Connect

    Sanville, Edward J; Bock, Nicolas; Challacombe, William M; Cawkwell, Marc J; Niklasson, Anders M N; Dattelbaum, Dana M; Sheffield, Stephen; Sewell, Thomas D

    2010-01-01

    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.

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

    PubMed

    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

    2012-03-01

    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 viaβ-C-C bond fission pathways of QOOH species derived from β- and γ-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 α-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

  16. 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)

    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

    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

  17. Synthesis chemistry of ceramics by solid-state combustion processes in micro-gravity

    SciTech Connect

    Valone, S.M.; Behrens, R.G.

    1985-01-01

    The method of solid-state combustion offers a way of producing refractory ceramics from the constituent elements. Since temperatures within the reaction zone are so high (2500 to 4000/sup 0/K), there is probably melting, and surface tension and gravity-induced convection may affect the mixing process. A strongly exothermic reaction can be used to drive a weakly exothermic or endothermic reaction. (DLC)

  18. Terascale High-Fidelity Simulations of Turbulent Combustion with Detailed Chemistry

    SciTech Connect

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

    2004-10-15

    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.

  19. FUNDAMENTAL COMBUSTION RESEARCH APPLIED TO POLLUTION FORMATION. VOLUME 2C. PHYSICS AND CHEMISTRY OF TWO-PHASE SYSTEMS: HETEROGENEOUS NO REDUCTION

    EPA Science Inventory

    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 IIc gives information on the kinetic rates and mechanisms of nitrogen ...

  20. The solubility of 40Ar in liquid hydrocarbons: implications for Titan's chemistry and evolution

    NASA Astrophysics Data System (ADS)

    Hodyss, R. P.; Beauchamp, P. M.; Choukroun, M.; Sotin, C.

    2011-12-01

    The solubility of argon in liquid methane and ethane has been experimentally determined at 94 K. The solubilities are very large: 47% in methane and 15% in ethane, making the lakes of Titan an important potential reservoir of 40Ar. The amount of argon in the Titan lakes can be several times the atmospheric amount. After describing the experimental results, we will compare them with available models for vapor-liquid equilibria in the CH4-N2-Ar system. Using the data obtained on the solubility of argon in ethane, we will also derive implications for calculating the vapor-liquid equilibria in the C2H6-N2-Ar system. We eventually discuss the reasons for such high solubilities in terms of Hildebrand solubility parameters and the implications for Titan's surface chemistry and evolution.

  1. Influence of combustion parameters on the formation of polychlorinated dibenzo-p-dioxins, dibenzofurans, benzenes, and biphenyls and polyaromatic hydrocarbons in a pilot incinerator

    SciTech Connect

    Faengmark, I.; Bavel, B. van; Marklund, S.; Rappe, C. ); Stroemberg, B.; Berge, N. )

    1993-08-01

    A laboratory-scale fluidized-bed incinerator was used to study the influence of several combustion parameters with respect to the emission of important aromatic contaminants including polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), polychlorinated benzenes (PCBz), polyaromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs). The parameters studied include bed temperature, O[sub 2]-concentration, variations in HCl and H[sub 2]O, and temperature and residence time in the postcombustion zone. A two-level fractional factorial design was used for planning the experiments. Flue gas samples were collected and analyzed on HRGC-HRMS. The most important parameter for the formation of the above chlorinated aromatics was found to be the residence time in the postcombustion zone. A substantial formation of the chlorinated compounds occurred during residence times as short as 1.6 s. PAH formation was found to be influenced by the oxygen concentration in the combustion air, and good combustion conditions favor low PAH emissions. 42 refs., 5 figs., 10 tabs.

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

    PubMed

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

    2001-01-01

    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

  3. Comparison of numerical techniques for integration of stiff ordinary differential equations arising in combustion chemistry

    NASA Technical Reports Server (NTRS)

    Radhakrishnan, K.

    1984-01-01

    The efficiency and accuracy of several algorithms recently developed for the efficient numerical integration of stiff ordinary differential equations are compared. The methods examined include two general-purpose codes, EPISODE and LSODE, and three codes (CHEMEQ, CREK1D, and GCKP84) developed specifically to integrate chemical kinetic rate equations. The codes are applied to two test problems drawn from combustion kinetics. The comparisons show that LSODE is the fastest code currently available for the integration of combustion kinetic rate equations. An important finding is that an interactive solution of the algebraic energy conservation equation to compute the temperature does not result in significant errors. In addition, this method is more efficient than evaluating the temperature by integrating its time derivative. Significant reductions in computational work are realized by updating the rate constants (k = at(supra N) N exp(-E/RT) only when the temperature change exceeds an amount delta T that is problem dependent. An approximate expression for the automatic evaluation of delta T is derived and is shown to result in increased efficiency.

  4. Spatially Resolved L-C3H+ Emission in the Horsehead Photodissociation Region: Further Evidence for a Top-Down Hydrocarbon Chemistry

    NASA Astrophysics Data System (ADS)

    Guzmán, V. V.; Pety, J.; Goicoechea, J. R.; Gerin, M.; Roueff, E.; Gratier, P.; Öberg, K. I.

    2015-02-01

    Small hydrocarbons, such as C2H, C3H, and C3H2 are more abundant in photo-dissociation regions (PDRs) than expected based on gas-phase chemical models. To explore the hydrocarbon chemistry further, we observed a key intermediate species, the hydrocarbon ion l-C3H+, in the Horsehead PDR with the Plateau de Bure Interferometer at high-angular resolution (6″). We compare with previous observations of C2H and c-C3H2 at similar angular resolution and new gas-phase chemical model predictions to constrain the dominant formation mechanisms of small hydrocarbons in low-UV flux PDRs. We find that at the peak of the HCO emission (PDR position), the measured l-C3H+, C2H, and c-C3H2 abundances are consistent with current gas-phase model predictions. However, in the first PDR layers, at the 7.7 μm polycyclic aromatic hydrocarbon band emission peak, which are more exposed to the radiation field and where the density is lower, the C2H and c-C3H2 abundances are underestimated by an order of magnitude. At this position, the l-C3H+ abundance is also underpredicted by the model but only by a factor of a few. In addition, contrary to the model predictions, l-C3H+ peaks further out in the PDR than the other hydrocarbons, C2H and c-C3H2. This cannot be explained by an excitation effect. Current gas-phase photochemical models thus cannot explain the observed abundances of hydrocarbons, in particular, in the first PDR layers. Our observations are consistent with a top-down hydrocarbon chemistry, in which large polyatomic molecules or small carbonaceous grains are photo-destroyed into smaller hydrocarbon molecules/precursors. Based on observations obtained with the IRAM Plateau de Bure interferometer and 30 m telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain).

  5. Bacterial and human cell mutagenicity study of some C18H10 cyclopenta-fused polycyclic aromatic hydrocarbons associated with fossil fuels combustion.

    PubMed Central

    Lafleur, A L; Longwell, J P; Marr, J A; Monchamp, P A; Plummer, E F; Thilly, W G; Mulder, P P; Boere, B B; Cornelisse, J; Lugtenburg, J

    1993-01-01

    A number of isomeric C18H10 polycyclic aromatic hydrocarbons (PAHs), thought to be primarily cyclopenta-fused PAHs, are produced during the combustion and pyrolysis of fossil fuels. To determine the importance of their contributions to the total mutagenic activity of combustion and pyrolysis samples in which they are found, we characterized reference quantities of four C18H10 CP-PAHs: benzo[ghi]fluoranthene (BF), cyclopenta[cd]pyrene (CPP), cyclopent[hi]acephenanthrylene (CPAP), and cyclopent[hi]aceanthrylene (CPAA). Synthesis of CPAA and CPAP is described. The availability of reference samples of these isomers also proved to be an essential aid in the identification of the C18H10 species often found in combustion and pyrolysis samples. Chemical analysis of selected combustion and pyrolysis samples showed that CPP was generally the most abundant C18H10 isomer, followed by CPAP and BF. CPAA was detected only in pyrolysis products from pure PAHs. We tested the four C18H10 PAHs for mutagenicity in a forward mutation assay using S. typhimurium. CPP, BF, and CPAA were roughly twice as mutagenic as benzo[a]pyrene (BaP), whereas CPAP was only slightly active. These PAHs were also tested for mutagenic activity in human cells. In this assay, CPP and CPAA were strongly mutagenic but less active than BaP, whereas CPAP and BF were inactive at the dose levels tested. Also, the bacterial and human cell mutagenicity of CPAA and CPAP were compared with the mutagenicity of their monocyclopenta-fused analogs, aceanthrylene and acephenanthyrlene. Although the mutagenicities of CPAP and acephenanthrylene are similar, the mutagenic activity of CPAA is an order of magnitude greater than that of aceanthyrlene. PMID:8354201

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

    SciTech Connect

    Rutland, Christopher J.

    2009-04-26

    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.

  7. Effects of the furnace temperature on the CO, CO{sub 2}, NO{sub x} and unburned hydrocarbon emissions from the combustion of coal and alternative fuels

    SciTech Connect

    Levendis, Y.A.; Atal, A.; Courtemanche, B.

    1999-07-01

    Results are presented on the emissions of carbon monoxide (CO), carbon dioxide (CO{sub 2}), unburned aromatic hydrocarbons, as well as oxides of nitrogen (NO{sub x}) from the combustion of pulverized bituminous coal, tire-derived fuel and, for a limited number of runs, waste plastics-derived fuel. The particle size cuts of pulverized coal, tire and plastics were 63--75 {micro}m and 180--300 {micro}m, respectively. Combustion experiments were conducted in a laboratory-scale drop-tube furnace at gas temperatures, in the range of 1,300--1,600 K, and several fuel mass loadings in the furnace, expressed in terms of global equivalence ratios in the range of 0.4--2.4. The CO, CO{sub 2} and NO{sub x} emissions were monitored continuously with infrared absorption and chemiluminescent instruments. Up to sixty 2-7 ring polynuclear aromatic hydrocarbons (PAH) were detected by capillary gas chromatography - mass spectrometry (GC-MS) techniques. Results showed that the PAH emission yields (mg/g fuel introduced) increased drastically with increasing bulk equivalence ratio (in the aforementioned range), at fixed furnace temperatures. This was also true for the CO yields, while the CO{sub 2} yields increased with increasing {o}, reached a maximum around stoichiometry and then decreased mildly. NO{sub x} yields decreased precipitously with increasing equivalence ratio. The CO and, especially, the PAH yields from tire-derived and plastics-derived fuels were much higher than those from coal, but the relative amounts of individual PAH components were remarkably similar in the combustion effluent of all fuels. The CO{sub 2} emissions and, especially, the NO{sub x} emissions from tire crumb were lower than those from coal. The CO{sub 2} emissions from plastics were comparable to those from coal, but their NO {sub x} emissions were much lower than those from tire. At fixed bulk equivalence ratios, however, as the furnace gas temperature increased the PAH yields from coal, tire crumb, and

  8. THERMOCHEMISTRY OF HYDROCARBON RADICALS

    SciTech Connect

    Kent M. Ervin, Principal Investigator

    2004-08-17

    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.

  9. Multigrid Method for Modeling Multi-Dimensional Combustion with Detailed Chemistry

    NASA Technical Reports Server (NTRS)

    Zheng, Xiaoqing; Liu, Chaoqun; Liao, Changming; Liu, Zhining; McCormick, Steve

    1996-01-01

    A highly accurate and efficient numerical method is developed for modeling 3-D reacting flows with detailed chemistry. A contravariant velocity-based governing system is developed for general curvilinear coordinates to maintain simplicity of the continuity equation and compactness of the discretization stencil. A fully-implicit backward Euler technique and a third-order monotone upwind-biased scheme on a staggered grid are used for the respective temporal and spatial terms. An efficient semi-coarsening multigrid method based on line-distributive relaxation is used as the flow solver. The species equations are solved in a fully coupled way and the chemical reaction source terms are treated implicitly. Example results are shown for a 3-D gas turbine combustor with strong swirling inflows.

  10. Finite rate chemistry and presumed PDF models for premixed turbulent combustion

    SciTech Connect

    Bray, K.N.C.; Swaminathan, N.; Champion, M.; Libby, P.A.

    2006-09-15

    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)

  11. Evaluation of joint probability density function models for turbulent nonpremixed combustion with complex chemistry

    NASA Technical Reports Server (NTRS)

    Smith, N. S. A.; Frolov, S. M.; Bowman, C. T.

    1996-01-01

    Two types of mixing sub-models are evaluated in connection with a joint-scalar probability density function method for turbulent nonpremixed combustion. Model calculations are made and compared to simulation results for homogeneously distributed methane-air reaction zones mixing and reacting in decaying turbulence within a two-dimensional enclosed domain. The comparison is arranged to ensure that both the simulation and model calculations a) make use of exactly the same chemical mechanism, b) do not involve non-unity Lewis number transport of species, and c) are free from radiation loss. The modified Curl mixing sub-model was found to provide superior predictive accuracy over the simple relaxation-to-mean submodel in the case studied. Accuracy to within 10-20% was found for global means of major species and temperature; however, nitric oxide prediction accuracy was lower and highly dependent on the choice of mixing sub-model. Both mixing submodels were found to produce non-physical mixing behavior for mixture fractions removed from the immediate reaction zone. A suggestion for a further modified Curl mixing sub-model is made in connection with earlier work done in the field.

  12. Chemical structures of low-pressure premixed methylcyclohexane flames as benchmarks for the development of a predictive combustion chemistry model

    SciTech Connect

    Skeen, Scott A.; Yang, Bin; Jasper, Ahren W.; Pitz, William J.; Hansen, Nils

    2011-11-14

    The chemical compositions of three low-pressure premixed flames of methylcyclohexane (MCH) are investigated with the emphasis on the chemistry of MCH decomposition and the formation of aromatic species, including benzene and toluene. The flames are stabilized on a flat-flame (McKenna type) burner at equivalence ratios of φ = 1.0, 1.75, and 1.9 and at low pressures between 15 Torr (= 20 mbar) and 30 Torr (= 40 mbar). The complex chemistry of MCH consumption is illustrated in the experimental identification of several C7H12, C7H10, C6H12, and C6H10 isomers sampled from the flames as a function of distance from the burner. Three initiation steps for MCH consumption are discussed: ring-opening to heptenes and methyl-hexenes (isomerization), methyl radical loss yielding the cyclohexyl radical (dissociation), and H abstraction from MCH. Mole fraction profiles as a function of distance from the burner for the C7 species supplemented by theoretical calculations are presented, indicating that flame structures resulting in steeper temperature gradients and/or greater peak temperatures can lead to a relative increase in MCH consumption through the dissociation and isomerization channels. Trends observed among the stable C6 species as well as 1,3-pentadiene and isoprene also support this conclusion. Relatively large amounts of toluene and benzene are observed in the experiments, illustrating the importance of sequential H-abstraction steps from MCH to toluene and from cyclohexyl to benzene. Furthermore, modeled results using the detailed chemical model of Pitz et al. (Proc. Combust. Inst.2007, 31, 267–275) are also provided to illustrate the use of these data as a benchmark for the improvement or future development of a MCH mechanism.

  13. Chemical structures of low-pressure premixed methylcyclohexane flames as benchmarks for the development of a predictive combustion chemistry model

    DOE PAGESBeta

    Skeen, Scott A.; Yang, Bin; Jasper, Ahren W.; Pitz, William J.; Hansen, Nils

    2011-11-14

    The chemical compositions of three low-pressure premixed flames of methylcyclohexane (MCH) are investigated with the emphasis on the chemistry of MCH decomposition and the formation of aromatic species, including benzene and toluene. The flames are stabilized on a flat-flame (McKenna type) burner at equivalence ratios of φ = 1.0, 1.75, and 1.9 and at low pressures between 15 Torr (= 20 mbar) and 30 Torr (= 40 mbar). The complex chemistry of MCH consumption is illustrated in the experimental identification of several C7H12, C7H10, C6H12, and C6H10 isomers sampled from the flames as a function of distance from the burner.more » Three initiation steps for MCH consumption are discussed: ring-opening to heptenes and methyl-hexenes (isomerization), methyl radical loss yielding the cyclohexyl radical (dissociation), and H abstraction from MCH. Mole fraction profiles as a function of distance from the burner for the C7 species supplemented by theoretical calculations are presented, indicating that flame structures resulting in steeper temperature gradients and/or greater peak temperatures can lead to a relative increase in MCH consumption through the dissociation and isomerization channels. Trends observed among the stable C6 species as well as 1,3-pentadiene and isoprene also support this conclusion. Relatively large amounts of toluene and benzene are observed in the experiments, illustrating the importance of sequential H-abstraction steps from MCH to toluene and from cyclohexyl to benzene. Furthermore, modeled results using the detailed chemical model of Pitz et al. (Proc. Combust. Inst.2007, 31, 267–275) are also provided to illustrate the use of these data as a benchmark for the improvement or future development of a MCH mechanism.« less

  14. Chemistry of the system: Al2O3(c)minus HCL aqueous. [chemical reactions resulting from propellant combustion of rocket propellants

    NASA Technical Reports Server (NTRS)

    Tyree, S. Y., Jr.

    1975-01-01

    In order to study exhaust gas chemistry for the space shuttle, the vapor pressure of 2 to 1 weight mixtures of 3-M hydrochloric acid and Al2O3 was studied over a l80 minute reaction period at 31 C. The Al2O3 sample was one of high surface area furnished by NASA Langley Research Center. A brief review is given for aqueous aluminum chemistry, and the chemical reactions of combustion products (exhaust gases) of aluminum propellant binders for the space shuttle are listed.

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

    PubMed

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

    2002-02-15

    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

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

    SciTech Connect

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

    2011-01-01

    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 performance of the exposed catalysts was evaluated on a laboratory bench-reactor fed with simulated exhaust. The Fe-zeolite NOx conversion efficiency was significantly degraded, especially at low temperatures (<250 C), after the catalyst was exposed to the engine exhaust. The degradation of the Fe-zeolite performance was similar for both combustion modes. The Cu-zeolite was much more resistant to HC fouling than the Fe-zeolite catalyst. In the case of the Cu-zeolite, PCCI exhaust had a more significant impact than the exhaust from conventional combustion on the NOx conversion efficiency. For all cases, the clean catalyst performance was recovered after heating to 600 C. GC-MS analysis of the HCs adsorbed to the catalyst surface provided insights into the observed NOx reduction performance trends.

  17. Effect of Hydrocarbon Emissions From PCCI-Type Combustion On The Performance of Selective Catalytic Reduction Catalysts

    SciTech Connect

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

    2011-01-01

    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 performance of the exposed catalysts was evaluated on a laboratory bench- reactor fed with simulated exhaust. The Fe-zeolite NOx conversion efficiency was significantly degraded, especially at low temperatures (<250 C), after the catalyst was exposed to the engine exhaust. The degradation of the Fe-zeolite performance was similar for both combustion modes. The Cu-zeolite was much more resistant to HC fouling than the Fe-zeolite catalyst. In the case of the Cu-zeolite, PCCI exhaust had a more significant impact than the exhaust from conventional combustion on the NOx conversion efficiency. For all cases, the clean catalyst performance was recovered after heating to 600 C. GC-MS analysis of the HCs adsorbed to the catalyst surface provided insights into the observed NOx reduction performance trends.

  18. Reconstruction of Biomass Combustion History Using Soot, Char, and Polycyclic Aromatic Hydrocarbons at Linsley Pond, Conn, USA

    NASA Astrophysics Data System (ADS)

    Yan, B.; Han, Y.; Peteet, D. M.

    2013-12-01

    Biomass burning has become recognized as one of key elements of climate change. The occurrence of fires is a complex function of climate, moisture, vegetation and landscape type. Fires impact environments in multiple ways, e.g., increase in soil erosion, change of vegetation type, and increase in nutrient levels in soils and lakes that receive runoff from burned areas. Sediment cores that contain an archive of deposition of combustion products can help reconstruct the history of past fires. In this study, alkylated PAHs and black carbon (char and soot) were used to explore the paleofire history reflected in a sediment core collected from Linsley Pond, Connecticut (41°18'N, 72 °45'W). Biomass type and combustion levels of these fires and whether they occurred locally or regionally can be derived from these indicators. Such details, together with other paleoenvironmental indicators recorded in sediment cores (e.g., pollen, macrofossils, and LOI) helped unravel the environmental conditions before and after fires. Alkanes, PAHs, alkylated PAHs, and the ratio of soot to char indicate that in the Younger Dryas, fire occurred at a relatively low temperature (i.e. smoldering), followed by an abrupt increase of flaming combustion of softwood (white pine) at the Holocene boundary. Our paleofire data supports the previous interpretations of a shift towards a warm and dry climate in the southern New England region at this time.

  19. Chemistry Notes.

    ERIC Educational Resources Information Center

    School Science Review, 1982

    1982-01-01

    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…

  20. δ13C and δD Measurement using Cavity Ring-down and Isotope Ratio Mass Spectrometry by Gas Chromatography/Combustion/Pyrolysis and Off-line Processing of Hydrocarbons

    NASA Astrophysics Data System (ADS)

    Culp, R.; Pan, H.; Saad, N.

    2015-12-01

    A comparison was made between various stable isotope measurement techniques for the purpose of quantifying each methods capability for use in hydrocarbon analyses applicable to fields such as geochemistry, agriculture, forensics and authenticity testing. Measurement techniques include: (1) Cavity Ring-down spectrometry (CRDS) using a Picarro 2120-A interfaced with a combustion module (CM) to facilitate conversion of hydrocarbons to carbon dioxide and water (2) Isotope Ratio Mass Spectrometry (IRMS) using a Thermo 253 IRMS with gas chromatographic separation prior to combustion to carbon dioxide or high temperature pyrolysis to hydrogen for isotope ratio measurement. Also, off line combustion to carbon dioxide and water with further reduction to hydrogen and dual-inlet measurement by IRMS. IRMS techniques have proven track records for measurement accuracy and precision but require independent analyses of carbon and hydrogen since one needs to oxidize carbon but reduce water to hydrogen prior to measurement or pyrolyze hydrocarbons directly into hydrogen after gas chromatographic separation. Cavity ring-down spectrometry can measure carbon dioxide and water simultaneously eliminating the need for two separate measurements of carbon and hydrogen isotopes. Although the CRDS suffers from memory effects following combustion and transfer of gases early on, new technology has reduced this to acceptable levels for accurate determinations of carbon and hydrogen isotope ratios. In this study, various hydrocarbon materials were used over an extended period of time to determine the best combination of sample size, replicate analyses and combustion column composition and life. The data presented here indicates isotopic measurements by CM-CRDS, for both solid and volatile liquid samples, compare well with GC/IRMS and off-line dual inlet methods of analysis.

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

    PubMed

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

    2015-06-01

    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 (Σ16 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

  2. An analytical study of nitrogen oxides and carbon monoxide emissions in hydrocarbon combustion with added nitrogen, preliminary results

    NASA Technical Reports Server (NTRS)

    Bittker, D. A.

    1979-01-01

    The effect of combustor operating conditions on the conversion of fuel-bound nitrogen (FBN) to nitrogen oxides NO sub x was analytically determined. The effect of FBN and of operating conditions on carbon monoxide (CO) formation was also studied. For these computations, the combustor was assumed to be a two stage, adiabatic, perfectly-stirred reactor. Propane-air was used as the combustible mixture and fuel-bound nitrogen was simulated by adding nitrogen atoms to the mixture. The oxidation of propane and formation of NO sub x and CO were modeled by a fifty-seven reaction chemical mechanism. The results for NO sub x and CO formation are given as functions of primary and secondary stage equivalence ratios and residence times.

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

    PubMed

    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

    2012-06-01

    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

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

    PubMed Central

    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

    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

  5. Polycyclic aromatic hydrocarbon exposure in household air pollution from solid fuel combustion among the female population of Xuanwei and Fuyuan counties, China.

    PubMed

    Downward, George S; Hu, Wei; Rothman, Nat; Reiss, Boris; Wu, Guoping; Wei, Fusheng; Chapman, Robert S; Portengen, Lutzen; Qing, Lan; Vermeulen, Roel

    2014-12-16

    Exposure to polycyclic aromatic hydrocarbons (PAHs) from burning "smoky" (bituminous) coal has been implicated as a cause of the high lung cancer incidence in the counties of Xuanwei and Fuyuan, China. Little is known about variations in PAH exposure from throughout the region nor how fuel source and stove design affects exposure. Indoor and personal PAH exposure resulting from solid fuel combustion in Xuanwei and Fuyuan was investigated using repeated 24 h particle bound and gas-phase PAH measurements, which were collected from 163 female residents of Xuanwei and Fuyuan. 549 particle bound (283 indoor and 266 personal) and 193 gas phase (all personal) PAH measurements were collected. Mixed effect models indicated that PAH exposure was up to 6 times higher when burning smoky coal than smokeless coal and varied by up to a factor of 3 between different smoky coal geographic sources. PAH measurements from unventilated firepits were up to 5 times that of ventilated stoves. Exposure also varied between different room sizes and season of measurement. These findings indicate that PAH exposure is modulated by a variety of factors, including fuel type, coal source, and stove design. These findings may provide valuable insight into potential causes of lung cancer in the area. PMID:25393345

  6. Polycyclic Aromatic Hydrocarbon Exposure in Household Air Pollution from Solid Fuel Combustion among the Female Population of Xuanwei and Fuyuan Counties, China

    PubMed Central

    2015-01-01

    Exposure to polycyclic aromatic hydrocarbons (PAHs) from burning “smoky” (bituminous) coal has been implicated as a cause of the high lung cancer incidence in the counties of Xuanwei and Fuyuan, China. Little is known about variations in PAH exposure from throughout the region nor how fuel source and stove design affects exposure. Indoor and personal PAH exposure resulting from solid fuel combustion in Xuanwei and Fuyuan was investigated using repeated 24 h particle bound and gas-phase PAH measurements, which were collected from 163 female residents of Xuanwei and Fuyuan. 549 particle bound (283 indoor and 266 personal) and 193 gas phase (all personal) PAH measurements were collected. Mixed effect models indicated that PAH exposure was up to 6 times higher when burning smoky coal than smokeless coal and varied by up to a factor of 3 between different smoky coal geographic sources. PAH measurements from unventilated firepits were up to 5 times that of ventilated stoves. Exposure also varied between different room sizes and season of measurement. These findings indicate that PAH exposure is modulated by a variety of factors, including fuel type, coal source, and stove design. These findings may provide valuable insight into potential causes of lung cancer in the area. PMID:25393345

  7. Emissions of parent, nitrated, and oxygenated polycyclic aromatic hydrocarbons from indoor corn straw burning in normal and controlled combustion conditions

    PubMed Central

    Shen, Guofeng; Xue, Miao; Wei, Siye; Chen, Yuanchen; Wang, Bin; Wang, Rong; Lv, Yan; Shen, Huizhong; Li, Wei; Zhang, Yanyan; Huang, Ye; Chen, Han; Wei, Wen; Zhao, Qiuyue; Li, Bin; Wu, Haisuo; Tao, Shu

    2014-01-01

    Emission factors (EFs) of parent polycyclic aromatic (pPAHs), nitrated PAHs (nPAHs), and oxygenated PAHs (oPAHs) were measured for indoor corn straw burned in a cooking brick stove in both normal and controlled burning conditions. EFs of total 28 pPAHs, 6 nPAHs and 4 oPAHs were 7.9±3.4, 6.5±1.6×10-3, and 6.1±1.4×10-1 mg/kg, respectively. By controlling the burning conditions, it was found that the influence of fuel charge size on EFs of the pPAHs and derivatives was insignificant. Measured EFs increased significantly in a fast burning mainly because of the oxygen deficient atmosphere formed in the stove chamber with a small volume. In both restricted and enhance air supply conditions, EFs of pPAHs, nPAHs and oPAHs were significantly higher than those measured in normal burning conditions. Though EFs varied in different burning conditions, the composition profiles and calculated isomer ratios were similar without significant differences. The results from the stepwise regression model showed that fuel burning rate, air supply amount, and modified combustion efficiency were three most significant influencing factors, explaining 72-85% of the total variations. PMID:24494494

  8. Light hydrocarbons from plasma discharge in H2-He-CH4 - First results and Uranian auroral chemistry

    NASA Technical Reports Server (NTRS)

    Thompson, W. Reid; Henry, Todd; Khare, B. N.; Flynn, Luke; Schwartz, Joel

    1987-01-01

    The production of light hydrocarbons by precipitating magnetospheric electrons in the Uranian stratosphere is simulated in laboratory experiments. The products of continuous-flow glow discharges of H2-He-CH4 mixtures containing 0.0012 or 0.022 mol pct CH4 at pressures 0.63-57 mbar are trapped at 77 K, measured manometrically, and identified by gas chromatography and mass spectroscopy; the results are presented in tables and characterized in detail. The globally averaged rate for the production of higher hydrocarbons by this mechanism on Uranus is estimated as 3 x 10 to the 6th C/sq cm sec and shown to be similar to that for photochemical production, while the local rate for the auroral zones is significantly higher than the corresponding photochemical rate. A decrease in yield with increasing molecular complexity is also noted.

  9. Structure and chemistry of a new chemical race of Botryococcus braunii (chlorophyceae) that produces lycopadiene, a tetraterpenoid hydrocarbon

    SciTech Connect

    Metzger, P.; Allard, B.; Casadevall, E. ); Berkaloff, C.; Coute, A. )

    1990-06-01

    New strains of the hydrocarbon rich alga Botryococcus braunii Kuetzing were isolated from water samples collected in three tropical freshwater lakes. These strains synthesize lycopadiene, a tetraterpenoid metabolite, as their sole hydrocarbon. The morphological and ultrastructural characteristics of these algae are similar to those reported for previously described strains which produce either alkadienes or botryococcenes. The pyriform shaped cells are embedded in a colonial matrix formed by layers of closely appressed external walls; this dense matrix is impregnated by the hydrocarbon and some other lipids. We believe the new strains synthesizing lycopadiene form a third chemical race in B. braunii, besides the alkadiene and botryococcene races, rather than a different species. Like the other two types of hydrocarbons, lycopadiene was produced primarily during the exponential and linear growth phases. The major fatty acid in the three races was oleic acid. This fatty acid was predominant in the alkadiene race; palmitic and octacosenoic acid also were present in appreciable amounts in the three races. Cholest-5-en-3{beta}-ol, 24-methylcholest-5-en-3{beta}-ol and 24-ethylcholest-5-en-3{beta}-ol occurred in the three races; three unidentified sterols also were detected in the lycopadiene race. Moreover, the presence of very long chain alkenyl-phenols in the lipids of algae of the alkadiene race was not observed in the botryococcene and lycopadiene races. Of the polysaccharides released in the medium, galactose appeared as a primary component: it predominated in the botryococcene race. The other major constituents were fucose for the alkadiene race and glucose and fucose for the lycopadiene race.

  10. Versatile transformations of hydrocarbons in anaerobic bacteria: substrate ranges and regio- and stereo-chemistry of activation reactions†

    PubMed Central

    Jarling, René; Kühner, Simon; Basílio Janke, Eline; Gruner, Andrea; Drozdowska, Marta; Golding, Bernard T.; Rabus, Ralf; Wilkes, Heinz

    2015-01-01

    Anaerobic metabolism of hydrocarbons proceeds either via addition to fumarate or by hydroxylation in various microorganisms, e.g., sulfate-reducing or denitrifying bacteria, which are specialized in utilizing n-alkanes or alkylbenzenes as growth substrates. General pathways for carbon assimilation and energy gain have been elucidated for a limited number of possible substrates. In this work the metabolic activity of 11 bacterial strains during anaerobic growth with crude oil was investigated and compared with the metabolite patterns appearing during anaerobic growth with more than 40 different hydrocarbons supplied as binary mixtures. We show that the range of co-metabolically formed alkyl- and arylalkyl-succinates is much broader in n-alkane than in alkylbenzene utilizers. The structures and stereochemistry of these products are resolved. Furthermore, we demonstrate that anaerobic hydroxylation of alkylbenzenes does not only occur in denitrifiers but also in sulfate reducers. We propose that these processes play a role in detoxification under conditions of solvent stress. The thermophilic sulfate-reducing strain TD3 is shown to produce n-alkylsuccinates, which are suggested not to derive from terminal activation of n-alkanes, but rather to represent intermediates of a metabolic pathway short-cutting fumarate regeneration by reverse action of succinate synthase. The outcomes of this study provide a basis for geochemically tracing such processes in natural habitats and contribute to an improved understanding of microbial activity in hydrocarbon-rich anoxic environments. PMID:26441848

  11. Combustion chemistry and flame structure of furan group biofuels using molecular-beam mass spectrometry and gas chromatography – Part II: 2-Methylfuran

    PubMed Central

    Tran, Luc-Sy; Togbé, Casimir; Liu, Dong; Felsmann, Daniel; Oßwald, Patrick; Glaude, Pierre-Alexandre; Fournet, René; Sirjean, Baptiste; Battin-Leclerc, Frédérique; Kohse-Höinghaus, Katharina

    2013-01-01

    This is Part II of a series of three papers which jointly address the combustion chemistry of furan and its alkylated derivatives 2-methylfuran (MF) and 2,5-dimethylfuran (DMF) under premixed low-pressure flame conditions. Some of them are considered to be promising biofuels. With furan as a common basis studied in Part I of this series, the present paper addresses two laminar premixed low-pressure (20 and 40 mbar) flat argon-diluted (50%) flames of MF which were studied with electron-ionization molecular-beam mass spectrometry (EI-MBMS) and gas chromatography (GC) for equivalence ratios φ=1.0 and 1.7, identical conditions to those for the previously reported furan flames. Mole fractions of reactants, products as well as stable and reactive intermediates were measured as a function of the distance above the burner. Kinetic modeling was performed using a comprehensive reaction mechanism for all three fuels given in Part I and described in the three parts of this series. A comparison of the experimental results and the simulation shows reasonable agreement, as also seen for the furan flames in Part I before. This set of experiments is thus considered to be a valuable additional basis for the validation of the model. The main reaction pathways of MF consumption have been derived from reaction flow analyses, and differences to furan combustion chemistry under the same conditions are discussed. PMID:24518895

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

    ERIC Educational Resources Information Center

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

    2007-01-01

    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 calorimetry…

  13. Sandia Combustion Research: Technical review

    SciTech Connect

    1995-07-01

    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.

  14. Forensic Chemistry

    NASA Astrophysics Data System (ADS)

    Bell, Suzanne

    2009-07-01

    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.

  15. Tripropellant combustion process

    NASA Technical Reports Server (NTRS)

    Kmiec, T. D.; Carroll, R. G.

    1988-01-01

    The addition of small amounts of hydrogen to the combustion of LOX/hydrocarbon propellants in large rocket booster engines has the potential to enhance the system stability. Programs being conducted to evaluate the effects of hydrogen on the combustion of LOX/hydrocarbon propellants at supercritical pressures are described. Combustion instability has been a problem during the development of large hydrocarbon fueled rocket engines. At the higher combustion chamber pressures expected for the next generation of booster engines, the effect of unstable combustion could be even more destructive. The tripropellant engine cycle takes advantage of the superior cooling characteristics of hydrogen to cool the combustion chamber and a small amount of the hydrogen coolant can be used in the combustion process to enhance the system stability. Three aspects of work that will be accomplished to evaluate tripropellant combustion are described. The first is laboratory demonstration of the benefits through the evaluation of drop size, ignition delay and burning rate. The second is analytical modeling of the combustion process using the empirical relationship determined in the laboratory. The third is a subscale demonstration in which the system stability will be evaluated. The approach for each aspect is described and the analytical models that will be used are presented.

  16. Combustor nozzle for a fuel-flexible combustion system

    DOEpatents

    Haynes, Joel Meier; Mosbacher, David Matthew; Janssen, Jonathan Sebastian; Iyer, Venkatraman Ananthakrishnan

    2011-03-22

    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.

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

    SciTech Connect

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

    1993-05-01

    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 to 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.

  18. DNA adducts as biomarkers for assessing exposure to polycyclic aromatic hydrocarbons in tissues from Xuan Wei women with high exposure to coal combustion emissions and high lung cancer mortality

    SciTech Connect

    Mumford, J.L.; Lee, X.; Lewtas, J.; Young, T.L.; Santella, R.M.

    1993-03-01

    The high lung cancer rate in Xuan Wei, China, is associated with smoky coal use in unvented homes. Smoky coal combustion emits higher levels of polycyclic aromatic hydrocarbons (PAH) than wood combustion. The study used DNA adducts as a biomarker for human exposure to PAH from combustion emissions. DNA adducts were determined by enzyme-linked immunosorbent assays (ELISA) in placentas and peripheral and cord white blood cells from Xuan Wei women burning smoky coal or wood and from Beijing women using natural gas. Color ELISA gave positive results in 58%, 47%, and 5% of the placentas from Xuan Wei women burning smoky coal without and with chimneys, and from Beijing women, respectively. Fluorescence ELISA indicated that 46%, 65%, 56%, and 25% of placentas were positive from Xuan Wei women without and with chimneys, Xuan Wei women burning wood, and Beijing controls, respectively. PAH-DNA adducts were detected in a higher percentage of placentas from Xuan Wei women exposed to smoky coal or wood emissions than those of the Beijing controls. The results suggest that DNA adducts can be used as a qualitative biomarker to assess human exposure to combustion emissions.

  19. A Dual-Line Detection Rayleigh Scattering Diagnostic Technique for the Combustion of Hydrocarbon Fuels and Filtered UV Rayleigh Scattering for Gas Velocity Measurements

    NASA Technical Reports Server (NTRS)

    Otugen, M. Volkan

    1997-01-01

    Non-intrusive techniques for the dynamic measurement of gas flow properties such as density, temperature and velocity, are needed in the research leading to the development of new generation high-speed aircraft. Accurate velocity, temperature and density data obtained in ground testing and in-flight measurements can help understand the flow physics leading to transition and turbulence in supersonic, high-altitude flight. Such non-intrusive measurement techniques can also be used to study combustion processes of hydrocarbon fuels in aircraft engines. Reliable, time and space resolved temperature measurements in various combustor configurations can lead to a better understanding of high temperature chemical reaction dynamics thus leading to improved modeling and better prediction of such flows. In view of this, a research program was initiated at Polytechnic University's Aerodynamics Laboratory with support from NASA Lewis Research Center through grants NAG3-1301 and NAG3-1690. The overall objective of this program has been to develop laser-based, non-contact, space- and time-resolved temperature and velocity measurement techniques. In the initial phase of the program a ND:YAG laser-based dual-line Rayleigh scattering technique was developed and tested for the accurate measurement of gas temperature in the presence of background laser glare. Effort was next directed towards the development of a filtered, spectrally-resolved Rayleigh/Mie scattering technique with the objective of developing an interferometric method for time-frozen velocity measurements in high-speed flows utilizing the uv line of an ND:YAG laser and an appropriate molecular absorption filter. This effort included both a search for an appropriate filter material for the 266 nm laser line and the development and testing of several image processing techniques for the fast processing of Fabry-Perot images for velocity and temperature information. Finally, work was also carried out for the development of

  20. Combustion modeling in internal combustion engines

    NASA Technical Reports Server (NTRS)

    Zeleznik, F. J.

    1976-01-01

    The fundamental assumptions of the Blizard and Keck combustion model for internal combustion engines are examined and a generalization of that model is derived. The most significant feature of the model is that it permits the occurrence of unburned hydrocarbons in the thermodynamic-kinetic modeling of exhaust gases. The general formulas are evaluated in two specific cases that are likely to be significant in the applications of the model.

  1. Influence of turbulence-chemistry interaction for n-heptane spray combustion under diesel engine conditions with emphasis on soot formation and oxidation

    NASA Astrophysics Data System (ADS)

    Bolla, Michele; Farrace, Daniele; Wright, Yuri M.; Boulouchos, Konstantinos; Mastorakos, Epaminondas

    2014-03-01

    The influence of the turbulence-chemistry interaction (TCI) for n-heptane sprays under diesel engine conditions has been investigated by means of computational fluid dynamics (CFD) simulations. The conditional moment closure approach, which has been previously validated thoroughly for such flows, and the homogeneous reactor (i.e. no turbulent combustion model) approach have been compared, in view of the recent resurgence of the latter approaches for diesel engine CFD. Experimental data available from a constant-volume combustion chamber have been used for model validation purposes for a broad range of conditions including variations in ambient oxygen (8‑21% by vol.), ambient temperature (900 and 1000 K) and ambient density (14.8 and 30 kg/m3). The results from both numerical approaches have been compared to the experimental values of ignition delay (ID), flame lift-off length (LOL), and soot volume fraction distributions. TCI was found to have a weak influence on ignition delay for the conditions simulated, attributed to the low values of the scalar dissipation relative to the critical value above which auto-ignition does not occur. In contrast, the flame LOL was considerably affected, in particular at low oxygen concentrations. Quasi-steady soot formation was similar; however, pronounced differences in soot oxidation behaviour are reported. The differences were further emphasised for a case with short injection duration: in such conditions, TCI was found to play a major role concerning the soot oxidation behaviour because of the importance of soot-oxidiser structure in mixture fraction space. Neglecting TCI leads to a strong over-estimation of soot oxidation after the end of injection. The results suggest that for some engines, and for some phenomena, the neglect of turbulent fluctuations may lead to predictions of acceptable engineering accuracy, but that a proper turbulent combustion model is needed for more reliable results.

  2. Small-scale combustion testing

    SciTech Connect

    Gibbon, G.A.; Ekmann, J.M.; White, C.M.; Navadauskas, R.J.; Retcofsky, H.L.; Joubert, J.I.

    1983-01-01

    In order to assess the possible environmental impact of substituting synfuels for petroleum in utility and industrial boilers, two experimental programs have been undertaken at the Pittsburgh Energy Technology Center. First, a fully instrumented 20-hp firetube boiler capable of burning liquid fuels ranging in combustion characteristics from No. 2 to No. 6 petroleum has been installed in the Combustion Division. Second, a sampling and analytical methodology for the organic compounds present in the exhaust duct of the 20-hp boiler is being developed by the Analytical Chemistry Division. This report outlines the progress on this project to date: twenty-four successful combustion runs have been completed on the 20-hp boiler, using a variety of petroleum-based fuels and synfuels; a sampling protocol for organic vapors in hot exhaust gases has been developed; significant differences in the composition of the trace organics in the exhaust gases have been observed as a function of the fuel being burned, but total polynuclear aromatic hydrocarbon levels are comparable for all fuels. 6 references, 10 tables.

  3. Formation and emission of large furans and oxygenated hydrocarbons from flames

    PubMed Central

    Johansson, K. Olof; Dillstrom, Tyler; Monti, Matteo; El Gabaly, Farid; Campbell, Matthew F.; Schrader, Paul E.; Popolan-Vaida, Denisia M.; Richards-Henderson, Nicole K.; Wilson, Kevin R.; Violi, Angela; Michelsen, Hope A.

    2016-01-01

    Many oxygenated hydrocarbon species formed during combustion, such as furans, are highly toxic and detrimental to human health and the environment. These species may also increase the hygroscopicity of soot and strongly influence the effects of soot on regional and global climate. However, large furans and associated oxygenated species have not previously been observed in flames, and their formation mechanism and interplay with polycyclic aromatic hydrocarbons (PAHs) are poorly understood. We report on a synergistic computational and experimental effort that elucidates the formation of oxygen-embedded compounds, such as furans and other oxygenated hydrocarbons, during the combustion of hydrocarbon fuels. We used ab initio and probabilistic computational techniques to identify low-barrier reaction mechanisms for the formation of large furans and other oxygenated hydrocarbons. We used vacuum-UV photoionization aerosol mass spectrometry and X-ray photoelectron spectroscopy to confirm these predictions. We show that furans are produced in the high-temperature regions of hydrocarbon flames, where they remarkably survive and become the main functional group of oxygenates that incorporate into incipient soot. In controlled flame studies, we discovered ∼100 oxygenated species previously unaccounted for. We found that large alcohols and enols act as precursors to furans, leading to incorporation of oxygen into the carbon skeletons of PAHs. Our results depart dramatically from the crude chemistry of carbon- and oxygen-containing molecules previously considered in hydrocarbon formation and oxidation models and spearhead the emerging understanding of the oxidation chemistry that is critical, for example, to control emissions of toxic and carcinogenic combustion by-products, which also greatly affect global warming. PMID:27410045

  4. Formation and emission of large furans and oxygenated hydrocarbons from flames.

    PubMed

    Johansson, K Olof; Dillstrom, Tyler; Monti, Matteo; El Gabaly, Farid; Campbell, Matthew F; Schrader, Paul E; Popolan-Vaida, Denisia M; Richards-Henderson, Nicole K; Wilson, Kevin R; Violi, Angela; Michelsen, Hope A

    2016-07-26

    Many oxygenated hydrocarbon species formed during combustion, such as furans, are highly toxic and detrimental to human health and the environment. These species may also increase the hygroscopicity of soot and strongly influence the effects of soot on regional and global climate. However, large furans and associated oxygenated species have not previously been observed in flames, and their formation mechanism and interplay with polycyclic aromatic hydrocarbons (PAHs) are poorly understood. We report on a synergistic computational and experimental effort that elucidates the formation of oxygen-embedded compounds, such as furans and other oxygenated hydrocarbons, during the combustion of hydrocarbon fuels. We used ab initio and probabilistic computational techniques to identify low-barrier reaction mechanisms for the formation of large furans and other oxygenated hydrocarbons. We used vacuum-UV photoionization aerosol mass spectrometry and X-ray photoelectron spectroscopy to confirm these predictions. We show that furans are produced in the high-temperature regions of hydrocarbon flames, where they remarkably survive and become the main functional group of oxygenates that incorporate into incipient soot. In controlled flame studies, we discovered ∼100 oxygenated species previously unaccounted for. We found that large alcohols and enols act as precursors to furans, leading to incorporation of oxygen into the carbon skeletons of PAHs. Our results depart dramatically from the crude chemistry of carbon- and oxygen-containing molecules previously considered in hydrocarbon formation and oxidation models and spearhead the emerging understanding of the oxidation chemistry that is critical, for example, to control emissions of toxic and carcinogenic combustion by-products, which also greatly affect global warming. PMID:27410045

  5. Chemistry Impacts in Gasoline HCCI

    SciTech Connect

    Szybist, James P; Bunting, Bruce G

    2006-09-01

    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

  6. A quantum chemistry study on thermochemical properties of high energy-density endothermic hydrocarbon fuel JP-10.

    PubMed

    Qin, Xiao-Mei; Xie, Hu-Jun; Yue, Lei; Lu, Xiao-Xing; Fang, Wen-Jun

    2014-04-01

    The density functional theory (DFT) calculations at the M06-2X/6-31++G(d,p) level have been performed to explore the molecular structure, electronic structure, C-H bond dissociation enthalpy, and reaction enthalpies for five isodesmic reactions of a high energy-density endothermic hydrocarbon fuel JP-10. On the basis of the calculations, it is found that the carbonium ion C-6 isomer formed from the catalytic cracking at the C₆ site of JP-10 has the lowest energy, and the R-5 radical generated from the thermal cracking at the C₅ site of JP-10 is the most stable isomer. Furthermore, a series of hypothetical and isodesmic work reactions containing similar bond environments are used to calculate the reaction enthalpies for target compounds. For the same isodesmic reaction, the reaction enthalpy of each carbon site radical has also been calculated. The present work is of fundamental significance and strategic importance to provide some valuable insights into the component design and energy utilization of advanced endothermic fuels. PMID:24633778

  7. Small scale combustion testing of synthetic fuels

    SciTech Connect

    Gibbon, G.A.; Ekmann, J.M.; Navadauskas, R.J.; White, C.M.

    1982-03-01

    In order to assess any changes in the environmental impact of industrial or utility boiler exhaust gases upon changing from petroleum-based fuels to synthetic fuels, detailed characterizations of the exhaust emissions from both types of fuels burned under identical combustion conditions are required. A 20-hp (approximately 5 gallons of liquid fuel feed per hour) firetube boiler has been installed in the Combustion Technology Division of the Pittsburgh Energy Technology Center (PETC) so such experiments can be performed. The boiler is fully instrumented for heat and material balance measurements, including analysis of the major and minor components of the combustion gases and the total hydrocarbons and particulates present in the gases. In addition, the exhaust duct of the boiler has a sampling port adjacent to the one used for major and minor components; this port is used to sample exhaust gases for the analysis of the trace organic compounds present in the gases. The Analytical Chemistry Division of PETC is developing the sampling and analytical methodologies for the trace organics. The effort to date has been focused on the problems involved in sampling the hot (ca. 350/sup 0/F) exhaust gases and on the analysis of the gases for polynuclear aromatic hydrocarbons.

  8. High Temperature Chemical Kinetic Combustion Modeling of Lightly Methylated Alkanes

    SciTech Connect

    Sarathy, S M; Westbrook, C K; Pitz, W J; Mehl, M

    2011-03-01

    Conventional petroleum jet and diesel fuels, as well as alternative Fischer-Tropsch (FT) fuels and hydrotreated renewable jet (HRJ) fuels, contain high molecular weight lightly branched alkanes (i.e., methylalkanes) and straight chain alkanes (n-alkanes). Improving the combustion of these fuels in practical applications requires a fundamental understanding of large hydrocarbon combustion chemistry. This research project presents a detailed high temperature chemical kinetic mechanism for n-octane and three lightly branched isomers octane (i.e., 2-methylheptane, 3-methylheptane, and 2,5-dimethylhexane). The model is validated against experimental data from a variety of fundamental combustion devices. This new model is used to show how the location and number of methyl branches affects fuel reactivity including laminar flame speed and species formation.

  9. Critical influence of finite rate chemistry and unmixedness on ignition and combustion of supersonic H2-air streams

    NASA Technical Reports Server (NTRS)

    Evans, J. S.; Schexnayder, C. J., Jr.

    1979-01-01

    Good agreement has been obtained between published profiles of composition and pitot pressure and the calculated results from a computer program in which finite rate chemistry was used. Significant differences are noted between results calculated using 7 species and 8 reactions and those calculated using 12 species and 25 reactions. Differences are also found between results in which the effect of unmixedness on reaction in turbulent flow is applied or is not applied.

  10. Hydrocarbon pneumonia

    MedlinePlus

    Pneumonia - hydrocarbon ... Coughing Fever Shortness of breath Smell of a hydrocarbon product on the breath Stupor (decreased level of ... Most children who drink or inhale hydrocarbon products and develop ... hydrocarbons may lead to rapid respiratory failure and death.

  11. Health effects of combustion-generated soot and polycyclic aromatic hydrocarbons. Progress report, May 1, 1979-April 30, 1980. [Lead abstract

    SciTech Connect

    Thilly, W. G.

    1980-05-01

    Mutagen studies on soot and soot components are reported in aspects dealing from quantitative chemical analyses of samples and mutagenesis of cells and microorganisms exposed to mutagens, to bioassay developments and techniques. Several polycyclic aromatic hydrocarbons are characterized and discussed.

  12. Comparison, limitations and uncertainty of wet chemistry techniques, loss on ignition and dry combustion in soil organic carbon analysis

    NASA Astrophysics Data System (ADS)

    Ćirić, Vladimir; Manojlović, Maja; Belić, Milivoj; Nešić, Ljiljana; Švarc-Gajić, Jaroslava; Sitaula, Bishal K.

    2014-05-01

    Soil organic carbon (SOC) has an important role in natural processes (carbon cycle, global climate change and plant growth), agriculture, soil protection and biodiversity. Determination of SOC is usually based on the oxidation of soil organic matter (SOM). Many methods are available, each with advantages and disadvantages in terms of accuracy, costs, convenience and repeatability. Therefore, it is necessary to make a comprehensive overview in order to select appropriate method with the purpose of accurate SOC determination. Most errors in SOC stocks assessment and SOC monitoring occur due to differences in analytical approaches and procedures. This can be a key factor in making incorrect conclusions. The purpose of this research was to compare methods for SOC determination and highlight the strengths and weaknesses of individual methods. The research was conducted on soil samples collected from different soil types and different land uses of temperate region. The concentration of SOC in every sample was determined by the following methods: Tyrin's method, Tyrin's method without addition of AgSO4, Kotzmann's method, loss on ignition (LOI) method, Walkley-Black method, dry combustion by CHN analyzer with pretreatment with HCl and subtraction of volumetrically determined soil inorganic carbon (SIC) from dry combustion by CHN analyzer without pretreatment. Each of the applied methods demonstrated specific limitations. The average SOC concentration determined by different methods ranged from 16.1-28.5 g kg-1. It has been established that different methods for the determination of total SOC recovered 76-157% of SOC compared to the reference dry combustion method by CHN analyzer. The correlation coefficients between applied methods ranged from 0.74-0.98. The Tyrin's method without addition of AgSO4 can be recommended as the most suitable method for the determination of SOC, with mandatory use of the correction factor 1.14. For the purpose of reducing the difference

  13. Numerical simulations in combustion

    NASA Technical Reports Server (NTRS)

    Chung, T. J.

    1989-01-01

    This paper reviews numerical simulations in reacting flows in general and combustion phenomena in particular. It is shown that use of implicit schemes and/or adaptive mesh strategies can improve convergence, stability, and accuracy of the solution. Difficulties increase as turbulence and multidimensions are considered, particularly when finite-rate chemistry governs the given combustion problem. Particular attention is given to the areas of solid-propellant combustion dynamics, turbulent diffusion flames, and spray droplet vaporization.

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

    SciTech Connect

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

    1980-11-01

    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.

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

    SciTech Connect

    Wang, J.; Kohse-Hoinghaus, Katharina; Cool, Terrill A.; Taatjes, Craig A.; Struckmeier, Ulf; OBwald, Patrick; Morel, Aude; Westmoreland, Phillip R.; Kasper, Tina Silvia

    2008-10-01

    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

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

    SciTech Connect

    Kasper, T.; Osswald, P.; Struckmeier, U.; Kohse-Hoeinghaus, K.; Taatjes, C.A.; Wang, J.; Cool, T.A.; Law, M.E.; Morel, A.; Westmoreland, P.R.

    2009-06-15

    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

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

    SciTech Connect

    Dryer, F.L.; Brezinsky, K.

    1990-09-01

    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.

  18. DNA adducts as biomarkers for assessing exposure to polycyclic aromatic hydrocarbons in tissues from Xuan Wei women with high exposure to coal combustion emissions and high lung cancer mortality.

    PubMed Central

    Mumford, J L; Lee, X; Lewtas, J; Young, T L; Santella, R M

    1993-01-01

    The high lung cancer rate in Xuan Wei, China, is associated with smoky coal use in unvented homes, but not with wood or smokeless coal use. Smoky coal combustion emits higher polycyclic aromatic hydrocarbon (PAH) concentrations than wood combustion. This study used DNA adducts as biomarkers for human exposure to PAH from combustion emissions. DNA adducts were determined by enzyme-linked immunosorbent assays (ELISA) in placentas and peripheral and cord white blood cells (WBC) from Xuan Wei women burning smoky coal or wood and from Beijing women using natural gas. Color ELISA gave positive results in 58, 47, and 5% of the placentas from Xuan Wei women burning smoky coal without and with chimneys, and from Beijing women, respectively. Fluorescence ELISA indicated that 46, 65, 56, and 25% of placentas were positive from Xuan Wei women who lived in houses without and with chimneys, Xuan Wei women burning wood, and Beijing controls, respectively. Peripheral WBC samples were positive in 7/9, 8/9, and 3/9 for the Xuan Wei women who lived in houses without and with chimneys and Beijing women, respectively. PAH-DNA adducts were detected in a higher percentage of placentas from Xuan Wei women living in houses exposed to smoky coal or wood emissions than from those of the Beijing controls. No dose-response relationship was observed between the air benzo[alpha]pyrene concentrations and DNA adduct levels or percentage of detectable samples. The results suggest that DNA adducts can be used as a qualitative biomarker to assess human exposure to combustion emissions. PMID:8319664

  19. Polynuclear aromatic hydrocarbons for fullerene synthesis in flames

    DOEpatents

    Alford, J. Michael; Diener, Michael D.

    2006-12-19

    This invention provides improved methods for combustion synthesis of carbon nanomaterials, including fullerenes, employing multiple-ring aromatic hydrocarbon fuels selected for high carbon conversion to extractable fullerenes. The multiple-ring aromatic hydrocarbon fuels include those that contain polynuclear aromatic hydrocarbons. More specifically, multiple-ring aromatic hydrocarbon fuels contain a substantial amount of indene, methylnapthalenes or mixtures thereof. Coal tar and petroleum distillate fractions provide low cost hydrocarbon fuels containing polynuclear aromatic hydrocarbons, including without limitation, indene, methylnapthalenes or mixtures thereof.

  20. DEVELOPMENT OF RELATIVE POTENCY ESTIMATES FOR PAHS AND HYDROCARBON COMBUSTION PRODUCT FRACTIONS COMPARED TO BENZO[A]PYRENE AND THEIR USE IN CARCINOGENIC RISK ASSESSMENTS

    EPA Science Inventory

    As an extension of the work started in a previous contract (EPA 68-02-4403, April 1988), various approaches for estimating the carcinogenic potency of polycyclic aromatic hydrocarbons (PAH) mixtures were investigated. he approach uses the two-stage model described in the previous...

  1. Formation of charged nanoparticles in hydrocarbon flames: principal mechanisms

    NASA Astrophysics Data System (ADS)

    Starik, A. M.; Savel'ev, A. M.; Titova, N. S.

    2008-11-01

    The processes of charged gaseous and particulate species formation in sooting hydrocarbon/air flame are studied. The original kinetic model, comprising the chemistry of neutral and charged gaseous species, generation of primary clusters, which then undergo charging due to attachment of ions and electrons to clusters and via thermoemission, and coagulation of charged-charged, charged-neutral and neutral-neutral particles, is reported. The analysis shows that the principal mechanisms of charged particle origin in hydrocarbon flames are associated with the attachment of ions and electrons produced in the course of chemoionization reactions to primary small clusters and particles and coagulation via charged-charged and charged-neutral particle interaction. Thermal ionization of particles does not play a significant role in the particle charging. This paper was presented at the Third International Symposium on Nonequilibrium Process, combustion, and Atmospheric Phenomena (Dagomys, Sochi, Russia, 25-29 June 2007).

  2. Measurement of spray combustion processes

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

    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.

  3. Application of single-particle laser desorption/ionization time-of-flight mass spectrometry for detection of polycyclic aromatic hydrocarbons from soot particles originating from an industrial combustion process.

    PubMed

    Zimmermann, R; Ferge, T; Gälli, M; Karlsson, R

    2003-01-01

    Combustion-related soot particles were sampled in situ from the stoker system of a 0.5 MW incineration pilot plant (feeding material was wood) at two different heights over the feed bed in the third air supply zone. The collected particles were re-aerosolized by a powder-dispersing unit and analyzed by a single-particle laser desorption/ionization (LDI) time-of-flight mass spectrometer (aerosol-time-of-flight mass spectrometry, ATOFMS). The ATOFMS instrument characterizes particles according to their aerodynamic size (laser velocimetry) and chemical composition (LDI mass spectrometry). Chemical species from the particles are laser desorbed/ionized by 266 nm Nd:YAG laser pulses. ATOFMS results on individual 'real world' particles in general give information on the bulk inorganic composition. Organic compounds, which are of much lower concentrations, commonly are not detectable. However, recent off-line laser microprobe mass spectrometric (LMMS) experiments on bulk soot aerosol samples have emphasized that organic compounds can be desorbed and ionized without fragmentation in LDI experiments from black carbonaceous matrices. This paper reports the successful transfer of the off-line results to on-line analysis of airborne soot particles by ATOFMS. The detection of polycyclic aromatic hydrocarbons from soot particles is addressed in detail. The results are interpreted in the context of the recent LMMS results. Furthermore, their relevance with respect to possible applications in on-line monitoring of combustion processes is discussed. PMID:12672141

  4. The History of Chemistry. The Case of the Supposed Isomerism of the Hydrocarbon Ethane in the Construction of Knowledge: Implications for Chemical Education.

    ERIC Educational Resources Information Center

    Cross, Roger T.; Price, Ronald F.

    2001-01-01

    Contends that chemical education proposals for changing the conception of chemistry literacy should include making explicit the relationship between chemistry as science and chemistry as technology. Illustrates the importance of distinguishing between scientific and technological activities by explaining the events and processes that are…

  5. Stack contamination effects during small-scale combustion testing of synthetic fuels

    SciTech Connect

    Douglas, L.J.; Gibbon, G.A.; White, C.M.

    1984-01-01

    The Analytical Chemistry Branch at the Pittsburgh Energy Technology Center has undertaken the assessment of the possible environmental impact of substituting synfuels for petroleum-based fuels in utility and industrial boilers. The assessment is based on a study of results obtained from the analysis of trace organic compounds present in the exaust gases of a fully instrumented 20-hp firetube boiler. The stack gases from petroleum-based fuels, synfuels, and methanol combustion tests have been sampled and analyzed by combined gas chromatography/mass spectrometry. The stack gas sampled during the combustion of methanol showed the presence of saturated and aromatiic hydrocarbons as well as detectable amounts of organic sulfur compounds, such as dibenzothiophene. The presence of these compounds could not be explained on the basis of methanol showed the presence of saturated and aromatic hydrocarbons as well as detectable amounts of organic sulfur compounds, such as dibenzothiophene. The presence of these compounds could not be explained on the basis of methanol combustion but suggests contamination of the 20-hp combustor-exhaust system from earlier tests using petroleum or coal-derived fuels. The previously established exhaust stack protocol was reviewed by the Combustion Technology Branch and the Analytical Chemistry Branch. It was decided that a more exhaustive protocol was required. When this revised protocol was instituted, cross-contamination and memory effects disappeared, and sampling integrity was reestablished, thus allowing the analytical data to be properly interpreted. 5 references, 7 figures, 5 tables.

  6. Method for producing viscous hydrocarbons

    DOEpatents

    Poston, Robert S.

    1982-01-01

    A method for recovering viscous hydrocarbons and synthetic fuels from a subterranean formation by drilling a well bore through the formation and completing the well by cementing a casing means in the upper part of the pay zone. The well is completed as an open hole completion and a superheated thermal vapor stream comprised of steam and combustion gases is injected into the lower part of the pay zone. The combustion gases migrate to the top of the pay zone and form a gas cap which provides formation pressure to produce the viscous hydrocarbons and synthetic fuels.

  7. Characterisation of polycyclic aromatic hydrocarbons in flue gas and residues of a full scale fluidized bed combustor combusting non-hazardous industrial waste.

    PubMed

    Van Caneghem, J; Vandecasteele, C

    2014-11-01

    This paper studies the fate of PAHs in full scale incinerators by analysing the concentration of the 16 EPA-PAHs in both the input waste and all the outputs of a full scale Fluidized Bed Combustor (FBC). Of the analysed waste inputs i.e. Waste Water Treatment (WWT) sludge, Refuse Derived Fuel (RDF) and Automotive Shredder Residue (ASR), RDF and ASR were the main PAH sources, with phenanthrene, fluoranthene and pyrene being the most important PAHs. In the flue gas sampled at the stack, naphthalene was the only predominant PAH, indicating that the PAHs in FBC's combustion gas were newly formed and did not remain from the input waste. Of the other outputs, the boiler and fly ash contained no detectable levels of PAHs, whereas the flue gas cleaning residue contained only low concentrations of naphthalene, probably adsorbed from the flue gas. The PAH fingerprint of the bottom ash corresponded rather well to the PAH fingerprint of the RDF and ASR, indicating that the PAHs in this output, in contrast to the other outputs, were mainly remainders from the PAHs in the waste inputs. A PAH mass balance showed that the total PAH input/output ratio of the FBC ranged from about 100 to about 2600 depending on the waste input composition and the obtained combustion conditions. In all cases, the FBC was clearly a net PAH sink. PMID:25002370

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

    NASA Astrophysics Data System (ADS)

    Kong, Song-Charng; Reitz, Rolf D.

    2003-06-01

    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.

  9. Studies in combustion dynamics

    SciTech Connect

    Koszykowski, M.L.

    1993-12-01

    The goal of this program is to develop a fundamental understanding and a quantitative predictive capability in combustion modeling. A large part of the understanding of the chemistry of combustion processes comes from {open_quotes}chemical kinetic modeling.{close_quotes} However, successful modeling is not an isolated activity. It necessarily involves the integration of methods and results from several diverse disciplines and activities including theoretical chemistry, elementary reaction kinetics, fluid mechanics and computational science. Recently the authors have developed and utilized new tools for parallel processing to implement the first numerical model of a turbulent diffusion flame including a {open_quotes}full{close_quotes} chemical mechanism.

  10. Environmental sensing and combustion diagnostics; Proceedings of the Meeting, Los Angeles, CA, Jan. 24, 25, 1991

    NASA Astrophysics Data System (ADS)

    Santoleri, Joseph J.

    The present volume on environmental sensing and combustion diagnostics discusses incineration systems applications, IR techniques applied to incineration systems, continuous emission monitors, and analyzers and sensors for process control and environmental monitoring. Attention is given to developing a trial burn plan, IR monitoring of combustion, gaseous incinerator emissions analysis by FTIR spectroscopy, and emissions monitoring by IR photoacoustic spectroscopy. Topics addressed include multicomponent analysis using established techniques, laser diagnostic techniques in a resonant incinerator, and use of Fourier transform spectroscopy in combustion effluent monitoring. Also discussed are extractive sampling systems for continuous emissions monitors, laser-induced fluorescence in contaminated soils, in situ monitoring for hydrocarbons using fiber optic chemical sensors, and advances in analytical chemistry. (For individual items see A93-25448 to A93-25450)

  11. Combustion Science for Cleaner Fuels

    SciTech Connect

    Ahmed, Musahid

    2014-10-17

    Musahid Ahmed discusses how he and his team use the Advanced Light Source (ALS) to study combustion chemistry at our '8 Big Ideas' Science at the Theater event on October 8th, 2014, in Oakland, California.

  12. Chemical kinetic simulation of hydrocarbon oxidation through the exhaust port of a spark ignition engine

    SciTech Connect

    Wu, K.C.; Hochgreb, S.

    1996-12-01

    The oxidation of unburned hydrocarbons, remaining in the cylinder of a spark-ignited engine after the main combustion event, takes place both in-cylinder and in the exhaust port. Hydrocarbons emerging from engine tailpipes consist of unburned fuel as well as products of incomplete combustion. This paper addresses the extent of oxidation and the production of nonfuel species in the exhaust port of a single-cylinder spark-ignition engine. Simulations of the unsteady thermal and composition state of the gases emerging from the cylinder were coupled to detailed chemistry models of the oxidation of hydrocarbons (propane, isooctane, methane, and ethane) to determine the change in the average composition of the gas as it passes through the exhaust port. The results are compared to previously measured speciated compositions of the exhaust gases at the exhaust port inlet and outlet. A stratification parameter to represent the growth of the thermal boundary layer due to heat transfer is added to the simplified unsteady plug flow simulation. Comparisons between model and experiment show that the concentration of products of incomplete combustion can only be adequately reproduced if stratification effects are taken into account.

  13. A Study of Cavitation-Ignition Bubble Combustion

    NASA Technical Reports Server (NTRS)

    Nguyen, Quang-Viet; Jacqmin, David A.

    2005-01-01

    We present the results of an experimental and computational study of the physics and chemistry of cavitation-ignition bubble combustion (CIBC), a process that occurs when combustible gaseous mixtures are ignited by the high temperatures found inside a rapidly collapsing bubble. The CIBC process was modeled using a time-dependent compressible fluid-dynamics code that includes finite-rate chemistry. The model predicts that gas-phase reactions within the bubble produce CO and other gaseous by-products of combustion. In addition, heat and mechanical energy release through a bubble volume-expansion phase are also predicted by the model. We experimentally demonstrate the CIBC process using an ultrasonically excited cavitation flow reactor with various hydrocarbon-air mixtures in liquid water. Low concentrations (< 160 ppm) of carbon monoxide (CO) emissions from the ultrasonic reactor were measured, and found to be proportional to the acoustic excitation power. The results of the model were consistent with the measured experimental results. Based on the experimental findings, the computational model, and previous reports of the "micro-diesel effect" in industrial hydraulic systems, we conclude that CIBC is indeed possible and exists in ultrasonically- and hydrodynamically-induced cavitation. Finally, estimates of the utility of CIBC process as a means of powering an idealized heat engine are also presented.

  14. Synthetic fuel aromaticity and staged combustion

    SciTech Connect

    Longanbach, J. R.; Chan, L. K.; Levy, A.

    1982-11-15

    Samples of middle and heavy SRC-II distillates were distilled into 50 C boiling point range fractions. These were characterized by measurements of their molecular weight, elemental analysis and basic nitrogen content and calculation of average molecular structures. The structures typically consisted of 1 to 3 aromatic rings fused to alicyclic rings with short, 1 to 3 carbon aliphatic side chains. The lower boiling fractions contained significant amounts (1 atom/molecule) of oxygen while the heavier fractions contained so few heteroatoms that they were essentially hydrocarbons. Laboratory scale oxidative-pyrolysis experiments were carried out at pyrolysis temperatures of 500 to 1100 C and oxygen concentrations from 0 to 100 percent of stoichiometry. Analysis of liquid products, collected in condensers cooled with liquid nitrogen showed that aromatization is a major reaction in the absence of oxygen. The oxygen-containing materials (phenolics) seem to be more resistant to thermal pyrolysis than unsubstituted aromatics. Nitrogen converts from basic to nonbasic forms at about 500 C. The nonbasic nitrogen is more stable and survives up to 700 C after which it is slowly removed. A recently constructed 50,000 Btu/hr staged combustor was used to study the chemistry of the nitrogen and aromatics. SRC II combustion was studied under fuel-rich, first-stage conditions at air/fuel ratios from 0.6 to 1.0 times stoichiometric. The chemistry of the fuel during combustion calls for further investigation in order to examine the mechanism by which HCN is evolved as a common intermediate for the formation of the nitrogen-containing gaseous combustion products. 25 references, 45 figures, 25 tables.

  15. Combustion Fundamentals Research

    NASA Technical Reports Server (NTRS)

    1984-01-01

    The various physical processes that occur in the gas turbine combustor and the development of analytical models that accurately describe these processes are discussed. Aspects covered include fuel sprays; fluid mixing; combustion dynamics; radiation and chemistry and numeric techniques which can be applied to highly turbulent, recirculating, reacting flow fields.

  16. A comprehensive detailed chemical kinetic reaction mechanism for combustion of n-alkane hydrocarbons from n-octane to n-hexadecane

    SciTech Connect

    Westbrook, Charles K.; Pitz, William J.; Herbinet, Olivier; Silke, Emma J.; Curran, Henry J.

    2009-01-15

    Detailed chemical kinetic reaction mechanisms have been developed to describe the pyrolysis and oxidation of nine n-alkanes larger than n-heptane, including n-octane (n-C{sub 8}H{sub 18}), n-nonane (n-C{sub 9}H{sub 20}), n-decane (n-C{sub 10}H{sub 22}), n-undecane (n-C{sub 11}H{sub 24}), n-dodecane (n-C{sub 12}H{sub 26}), n-tridecane (n-C{sub 13}H{sub 28}), n-tetradecane (n-C{sub 14}H{sub 30}), n-pentadecane (n-C{sub 15}H{sub 32}), and n-hexadecane (n-C{sub 16}H{sub 34}). These mechanisms include both high temperature and low temperature reaction pathways. The mechanisms are based on previous mechanisms for the primary reference fuels n-heptane and iso-octane, using the reaction classes first developed for n-heptane. Individual reaction class rules are as simple as possible in order to focus on the parallelism between all of the n-alkane fuels included in the mechanisms. These mechanisms are validated through extensive comparisons between computed and experimental data from a wide variety of different sources. In addition, numerical experiments are carried out to examine features of n-alkane combustion in which the detailed mechanisms can be used to compare reactivities of different n-alkane fuels. The mechanisms for these n-alkanes are presented as a single detailed mechanism, which can be edited to produce efficient mechanisms for any of the n-alkanes included, and the entire mechanism, with supporting thermochemical and transport data, together with an explanatory glossary explaining notations and structural details, is available for download from our web page. (author)

  17. Measurements of C2-C7 hydrocarbons during the Polar Sunrise Experiment 1994: Further evidence for halogen chemistry in the troposphere

    NASA Astrophysics Data System (ADS)

    Ariya, P. A.; Jobson, B. T.; Sander, R.; Niki, H.; Harris, G. W.; Hopper, J. F.; Anlauf, K. G.

    1998-06-01

    Air samples for nonmethane hydrocarbon (NMHC) analysis were collected at two ground-based sites: Alert, Northwest Territories (82.5°N, 62.3°W) and Narwhal ice camp, an ice floe 140 km northwest of Alert, from Julian days 90 to 117, 1994, and on a 2-day aerial survey conducted on Julian days 89 and 90, 1994 over the Arctic archipelago. Several ozone depletion events and concurrent decreases in hydrocarbon concentrations relative to their background levels were observed at Alert and Narwhal ice camp. At Narwhal, a long period (≥7 days) of ozone depletion was observed during which a clear decay of alkane concentration occurred. A kinetic analysis led to a calculated Cl atom concentration of 4.5×103 cm-3 during this period. Several low-ozone periods concurrent with NMHC concentration decreases were observed over a widespread region of the Arctic region (82°-85°N, and 51°-65°W). Hydrocarbon measurements during the aerial survey indicated that the low concentrations of these species occurred only in the boundary layer. In all ozone depletion periods, concentration changes of alkanes and toluene were consistent with Cl atom reactions. The changes in ethyne concentration from its background level were in excess of those expected from Cl atom kinetics alone and are attributed to additional Br atom reactions. A box modeling exercise suggested that the Cl and particularly Br atom concentrations required to explain the hydrocarbon behavior are also sufficient to destroy ozone.

  18. Probing flame chemistry with MBMS, theory, and modeling

    SciTech Connect

    Westmoreland, P.R.

    1993-12-01

    The objective is to establish kinetics of combustion and molecular-weight growth in C{sub 3} hydrocarbon flames as part of an ongoing study of flame chemistry. Specific reactions being studied are (1) the growth reactions of C{sub 3}H{sub 5} and C{sub 3}H{sub 3} with themselves and with unsaturated hydrocarbons and (2) the oxidation reactions of O and OH with C{sub 3}`s. This approach combines molecular-beam mass spectrometry (MBMS) experiments on low-pressure flat flames; theoretical predictions of rate constants by thermochemical kinetics, Bimolecular Quantum-RRK, RRKM, and master-equation theory; and whole-flame modeling using full mechanisms of elementary reactions.

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

    PubMed

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

    2000-09-01

    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

  20. Radiation Chemistry

    NASA Astrophysics Data System (ADS)

    Wojnárovits, L.

    Ionizing radiation causes chemical changes in the molecules of the interacting medium. The initial molecules change to new molecules, resulting in changes of the physical, chemical, and eventually biological properties of the material. For instance, water decomposes to its elements H2 and O2. In polymers, degradation and crosslinking take place. In biopolymers, e.g., DNS strand breaks and other alterations occur. Such changes are to be avoided in some cases (radiation protection), however, in other cases they are used for technological purposes (radiation processing). This chapter introduces radiation chemistry by discussing the sources of ionizing radiation (radionuclide sources, machine sources), absorption of radiation energy, techniques used in radiation chemistry research, and methods of absorbed energy (absorbed dose) measurements. Radiation chemistry of different classes of inorganic (water and aqueous solutions, inorganic solids, ionic liquids (ILs)) and organic substances (hydrocarbons, halogenated compounds, polymers, and biomolecules) is discussed in concise form together with theoretical and experimental backgrounds. An essential part of the chapter is the introduction of radiation processing technologies in the fields of polymer chemistry, food processing, and sterilization. The application of radiation chemistry to nuclear technology and to protection of environment (flue gas treatment, wastewater treatment) is also discussed.

  1. Diterpenoid tetracyclic hydrocarbons of petroleum

    SciTech Connect

    Vorob'eva, N.S.; Zemskova, Z.K.; Pekh, T.I.; Petrov, A.A.

    1987-08-01

    Diterpenoid hydrocarbons are fairly widespread in various caustobioliths. However, if petroleums contain mainly acyclic diterpenoids (phytane, pristane and norpristane), cyclic diterpaenes such as fichtelite, pimarane, iosene (kaurane) and hibbane are often found in hydrocarbons isolated from coal and shale. Recent advances in the chemistry of diterpenoids isolated from caustobioliths, are described in a separate paper. Much less is known about petroleum polycyclic diterpenoid hydrocarbons, particularly those with four saturated rings. A series of tetracyclic hydrocarbons C/sub 19/H/sub 32/ (molar mass 260), found in a number of light petroleums and gas condensates from the Jura deposits of Central Kara-Kum (Turkmen S.S.R.), are examined here. These hydrocarbons are present in petroleums and condensates from the Davaly, Erden, Ortakak, Southern Beuideshik deposits, they are always identical and occur in the same ratios. The composition of the tretracyclanes isolated from the Ortakak gas condensates (well 17) will be examined in detail.

  2. Preliminary assessment of combustion modes for internal combustion wave rotors

    NASA Technical Reports Server (NTRS)

    Nalim, M. Razi

    1995-01-01

    Combustion within the channels of a wave rotor is examined as a means of obtaining pressure gain during heat addition in a gas turbine engine. Several modes of combustion are considered and the factors that determine the applicability of three modes are evaluated in detail; premixed autoignition/detonation, premixed deflagration, and non-premixed compression ignition. The last two will require strong turbulence for completion of combustion in a reasonable time in the wave rotor. The compression/autoignition modes will require inlet temperatures in excess of 1500 R for reliable ignition with most hydrocarbon fuels; otherwise, a supplementary ignition method must be provided. Examples of combustion mode selection are presented for two core engine applications that had been previously designed with equivalent 4-port wave rotor topping cycles using external combustion.

  3. Nox reduction system utilizing pulsed hydrocarbon injection

    DOEpatents

    Brusasco, Raymond M.; Penetrante, Bernardino M.; Vogtlin, George E.; Merritt, Bernard T.

    2001-01-01

    Hydrocarbon co-reductants, such as diesel fuel, are added by pulsed injection to internal combustion engine exhaust to reduce exhaust NO.sub.x to N.sub.2 in the presence of a catalyst. Exhaust NO.sub.x reduction of at least 50% in the emissions is achieved with the addition of less than 5% fuel as a source of the hydrocarbon co-reductants. By means of pulsing the hydrocarbon flow, the amount of pulsed hydrocarbon vapor (itself a pollutant) can be minimized relative to the amount of NO.sub.x species removed.

  4. New technique for calibrating hydrocarbon gas flowmeters

    NASA Technical Reports Server (NTRS)

    Singh, J. J.; Puster, R. L.

    1984-01-01

    A technique for measuring calibration correction factors for hydrocarbon mass flowmeters is described. It is based on the Nernst theorem for matching the partial pressure of oxygen in the combustion products of the test hydrocarbon, burned in oxygen-enriched air, with that in normal air. It is applied to a widely used type of commercial thermal mass flowmeter for a number of hydrocarbons. The calibration correction factors measured using this technique are in good agreement with the values obtained by other independent procedures. The technique is successfully applied to the measurement of differences as low as one percent of the effective hydrocarbon content of the natural gas test samples.

  5. Resonance ionization detection of combustion radicals

    SciTech Connect

    Cool, T.A.

    1993-12-01

    Fundamental research on the combustion of halogenated organic compounds with emphasis on reaction pathways leading to the formation of chlorinated aromatic compounds and the development of continuous emission monitoring methods will assist in DOE efforts in the management and disposal of hazardous chemical wastes. Selective laser ionization techniques are used in this laboratory for the measurement of concentration profiles of radical intermediates in the combustion of chlorinated hydrocarbon flames. A new ultrasensitive detection technique, made possible with the advent of tunable VUV laser sources, enables the selective near-threshold photoionization of all radical intermediates in premixed hydrocarbon and chlorinated hydrocarbon flames.

  6. Organic Experiments for Introductory Chemistry.

    ERIC Educational Resources Information Center

    Rayner-Canham, Geoff

    1985-01-01

    Describes test-tube organic chemistry procedures (using comparatively safe reagents) for the beginning student. These procedures are used to: examine differences between saturated and unsaturated hydrocarbons; compare structural isomers; and compare organic and inorganic acids and bases. (DH)

  7. Sandia Combustion Research Program

    SciTech Connect

    Johnston, S.C.; Palmer, R.E.; Montana, C.A.

    1988-01-01

    During the late 1970s, in response to a national energy crisis, Sandia proposed to the US Department of Energy (DOE) a new, ambitious program in combustion research. 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 inventories, industry, and national laboratories--to improve our understanding and control of combustion. This report includes descriptions several research projects which have been simulated by working groups and involve the on-site participation of industry scientists. DOE's Industry Technology Fellowship program, supported through the Office of Energy Research, has been instrumental in the success of some of these joint efforts. The remainder of this report presents results of calendar year 1988, separated thematically into eleven categories. Referred journal articles appearing in print during 1988 and selected other publications are included at the end of Section 11. Our traditional'' research activities--combustion chemistry, reacting flows, diagnostics, engine and coal combustion--have been supplemented by a new effort aimed at understanding combustion-related issues in the management of toxic and hazardous materials.

  8. Combustion noise

    NASA Technical Reports Server (NTRS)

    Strahle, W. C.

    1977-01-01

    A review of the subject of combustion generated noise is presented. Combustion noise is an important noise source in industrial furnaces and process heaters, turbopropulsion and gas turbine systems, flaring operations, Diesel engines, and rocket engines. The state-of-the-art in combustion noise importance, understanding, prediction and scaling is presented for these systems. The fundamentals and available theories of combustion noise are given. Controversies in the field are discussed and recommendations for future research are made.

  9. Small-scale combustion testing of synthetic fuels

    SciTech Connect

    Gibbon, G.A.; Ekmann, J.M.; White, C.M.; Navadauskas, R.J.; Joubert, J.I.; Retcofsky, H.L.

    1981-11-01

    In order to assess the possible environmental impact of substituting synfuels for petroleum in utility and industrial boilers, two experimental programs have been undertaken at the Pittsburgh Energy Technology Center. First, a fully instrumented 20-hp firetube boiler capable of burning liquid fuels ranging in combustion characteristics from No. 2 to No. 6 petroleum has been installed in the Combustion Division. Second, a sampling and analytical methodology for the organic compounds present in the exhaust duct of the 20-hp boiler is being developed by the Analytical Chemistry Division. This report outlines the progress on this project to date: twenty-four successful combustion runs have been completed on the 20-hp boiler, using a variety of petroleum-based fuels and synfuels; a sampling protocol for organic vapors in hot exhaust gases has been developed; significant differences in the composition of the trace organics in the exhaust gases have been observed as a function of the fuel being burned, but total polynuclear aromatic hydrocarbon levels are comparable for all fuels.

  10. A mechanistic model of the pyrolysis chemistry of 4-(1-naphthylmethyl)bibenzyl as a probe of hydrocarbon structure/reactivity relationships

    SciTech Connect

    Walter, T.D.; Klein, M.T.

    1995-12-01

    A mechanistic model of the pyrolysis chemistry of 4-(1-naphthylmethyl)bibenzyl (NBBM) was developed. The elementary steps within NBBM hydropyrolysis reaction families were summarized in the form of reaction matrices, each with a set of associated rules. The pyrolysis model was constructed through the application of the matrices and rules to the components of the reacting system. The kinetics within each reaction family were constrained to follow Polanyi relationships. The Polanyi relation parameters were regressed to fit the model predictions with observed experimental yields for NBBM hydropyrolysis at 420 C. The model was validated by the close agreement between experimental findings and model predictions and then used to probe the controlling mechanisms of NBBM pyrolysis.

  11. Method for in situ combustion

    DOEpatents

    Pasini, III, Joseph; Shuck, Lowell Z.; Overbey, Jr., William K.

    1977-01-01

    This invention relates to an improved in situ combustion method for the recovery of hydrocarbons from subterranean earth formations containing carbonaceous material. The method is practiced by penetrating the subterranean earth formation with a borehole projecting into the coal bed along a horizontal plane and extending along a plane disposed perpendicular to the plane of maximum permeability. The subterranean earth formation is also penetrated with a plurality of spaced-apart vertical boreholes disposed along a plane spaced from and generally parallel to that of the horizontal borehole. Fractures are then induced at each of the vertical boreholes which project from the vertical boreholes along the plane of maximum permeability and intersect the horizontal borehole. The combustion is initiated at the horizontal borehole and the products of combustion and fluids displaced from the earth formation by the combustion are removed from the subterranean earth formation via the vertical boreholes. Each of the vertical boreholes are, in turn, provided with suitable flow controls for regulating the flow of fluid from the combustion zone and the earth formation so as to control the configuration and rate of propagation of the combustion zone. The fractures provide a positive communication with the combustion zone so as to facilitate the removal of the products resulting from the combustion of the carbonaceous material.

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

    SciTech Connect

    Sankaran, R.; Grout, R.

    2012-01-01

    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.

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

    SciTech Connect

    Grout, Ray W

    2012-01-01

    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.

  14. Provisional Guidance for Quantitative Risk Assessment of Polycyclic Aromatic Hydrocarbons

    EPA Science Inventory

    Polycyclic Aromatic Hydrocarbons (PAHs) are products of incomplete combustion of organic materials; sources are, thus, widespread,including cigarette smoke, municipal waste incineration, wood stove emissions, coal conversion, energy production form fossil fuels, and automobile an...

  15. A Novel Philosophy for a First Course in Organic Chemistry.

    ERIC Educational Resources Information Center

    Newman, Melvin S.

    1982-01-01

    Focusing on research is suggested as an approach for teaching organic chemistry for nonmajors. Topics of saturated hydrocarbons and unsaturated hydrocarbons are used as examples to illustrate the approach. (SK)

  16. Forensic source differentiation of petrogenic, pyrogenic, and biogenic hydrocarbons in Canadian oil sands environmental samples.

    PubMed

    Wang, Zhendi; Yang, C; Parrott, J L; Frank, R A; Yang, Z; Brown, C E; Hollebone, B P; Landriault, M; Fieldhouse, B; Liu, Y; Zhang, G; Hewitt, L M

    2014-04-30

    To facilitate monitoring efforts, a forensic chemical fingerprinting methodology has been applied to characterize and differentiate pyrogenic (combustion derived) and biogenic (organism derived) hydrocarbons from petrogenic (petroleum derived) hydrocarbons in environmental samples from the Canadian oil sands region. Between 2009 and 2012, hundreds of oil sands environmental samples including water (snowmelt water, river water, and tailings pond water) and sediments (from river beds and tailings ponds) have been analyzed. These samples were taken from sites where assessments of wild fish health, invertebrate communities, toxicology and detailed chemistry are being conducted as part of the Canada-Alberta Joint Oil Sands Monitoring Plan (JOSMP). This study describes the distribution patterns and potential sources of PAHs from these integrated JOSMP study sites, and findings will be linked to responses in laboratory bioassays and in wild organisms collected from these same sites. It was determined that hydrocarbons in Athabasca River sediments and waters were most likely from four sources: (1) petrogenic heavy oil sands bitumen; (2) biogenic compounds; (3) petrogenic hydrocarbons of other lighter fuel oils; and (4) pyrogenic PAHs. PAHs and biomarkers detected in snowmelt water samples collected near mining operations imply that these materials are derived from oil sands particulates (from open pit mines, stacks and coke piles). PMID:24632369

  17. Hydrocarbon-enhanced particulate filter regeneration via microwave ignition

    DOEpatents

    Gonze, Eugene V.; Brown, David B.

    2010-02-02

    A regeneration method for a particulate filter includes estimating a quantity of particulate matter trapped within the particulate filter, comparing the quantity of particulate matter to a predetermined quantity, heating at least a portion of the particulate filter to a combustion temperature of the particulate matter, and introducing hydrocarbon fuel to the particulate filter. The hydrocarbon fuel facilitates combustion of the particulate matter to regenerate the particulate filter.

  18. Negative Valve Overlap Reforming Chemistry in Low-Oxygen Environments

    SciTech Connect

    Szybist, James P; Steeper, Richard R.; Splitter, Derek A; Kalaskar, Vickey B; Pihl, Josh A; Daw, C Stuart

    2014-01-01

    Fuel injection into the negative valve overlap (NVO) period is a common method for controlling combustion phasing in homogeneous charge compression ignition (HCCI) and other forms of advanced combustion. When fuel is injected into O2-deficient NVO conditions, a portion of the fuel can be converted to products containing significant levels of H2 and CO. Additionally, other short chain hydrocarbons are produced by means of thermal cracking, water-gas shift, and partial oxidation reactions. The present study experimentally investigates the fuel reforming chemistry that occurs during NVO. To this end, two very different experimental facilities are utilized and their results are compared. One facility is located at Oak Ridge National Laboratory, which uses a custom research engine cycle developed to isolate the NVO event from main combustion, allowing a steady stream of NVO reformate to be exhausted from the engine and chemically analyzed. The other experimental facility, located at Sandia National Laboratories, uses a dump valve to capture the exhaust from a single NVO event for analysis. Results from the two experiments are in excellent trend-wise agreement and indicate that the reforming process under low-O2 conditions produces substantial concentrations of H2, CO, methane, and other short-chain hydrocarbon species. The concentration of these species is found to be strongly dependent on fuel injection timing and injected fuel type, with weaker dependencies on NVO duration and initial temperature, indicating that NVO reforming is kinetically slow. Further, NVO reforming does not require a large energy input from the engine, meaning that it is not thermodynamically expensive. The implications of these results on HCCI and other forms of combustion are discussed in detail.

  19. Upper troposphere and stratosphere distribution of hydrocarbon species in ACE-FTS measurements and GEOS-Chem simulations

    NASA Astrophysics Data System (ADS)

    Koo, Ja-Ho; Walker, Kaley A.; Jones, Dylan B. A.; Jones, Ashley; Sheese, Patrick E.; Boone, Chris D.; Bernath, Peter F.; Manney, Gloria L.

    2016-04-01

    Measurements of carbon-containing species, referred to herein as "hydrocarbons", are important components needed for describing and understanding the influence of natural and anthropogenic emissions on atmospheric chemistry. Analysis of the global pattern of hydrocarbons contributes to our understanding of the influence of regional and seasonal variation in air pollution and natural fire events. The Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) has monitored trace gases in the upper troposphere and stratosphere based on solar occultation measurements for more than ten years. In this study, we investigate the global pattern of seven "hydrocarbon" species (CO, C2H6, C2H2, HCN, H2CO, CH3OH, and HCOOH) and OCS using the ACE-FTS version 3.5 dataset from 2004 to 2013. All hydrocarbons show strong seasonal variation and regional differences, but the detailed pattern differs according to the speciation of the hydrocarbons. For example, in the Northern Hemisphere, CO, C2H6, and C2H2 show the highest mixing ratios in winter, but high CH3OH and HCOOH appear in summer. In the Southern hemisphere, H2CO, HCN, and HCOOH show high mixing ratios in springtime. These patterns indicate the impact of different emission sources including fuel combustion, wildfire emission, and chemical production. By calculating correlations with CO, these results can provide useful information to characterize each hydrocarbon emission. The ACE-FTS measurements have also been compared with GEOS-Chem output to examine the model performance and spatiotemporal patterns in the simulations.

  20. Computational Combustion

    SciTech Connect

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

    2004-08-26

    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.

  1. A Role of the Reaction Kernel in Propagation and Stabilization of Edge Diffusion Flames of C1-C3 Hydrocarbons

    NASA Technical Reports Server (NTRS)

    Takahashi, Fumiaki; Katta, Viswanath R.

    2003-01-01

    Diffusion flame stabilization is of essential importance in both Earth-bound combustion systems and spacecraft fire safety. Local extinction, re-ignition, and propagation processes may occur as a result of interactions between the flame zone and vortices or fire-extinguishing agents. By using a computational fluid dynamics code with a detailed chemistry model for methane combustion, the authors have revealed the chemical kinetic structure of the stabilizing region of both jet and flat-plate diffusion flames, predicted the flame stability limit, and proposed diffusion flame attachment and detachment mechanisms in normal and microgravity. Because of the unique geometry of the edge of diffusion flames, radical back-diffusion against the oxygen-rich entrainment dramatically enhanced chain reactions, thus forming a peak reactivity spot, i.e., reaction kernel, responsible for flame holding. The new results have been obtained for the edge diffusion flame propagation and attached flame structure using various C1-C3 hydrocarbons.

  2. Simulating Combustion

    NASA Astrophysics Data System (ADS)

    Merker, G.; Schwarz, C.; Stiesch, G.; Otto, F.

    The content spans from simple thermodynamics of the combustion engine to complex models for the description of the air/fuel mixture, ignition, combustion and pollutant formation considering the engine periphery of petrol and diesel engines. Thus the emphasis of the book is on the simulation models and how they are applicable for the development of modern combustion engines. Computers can be used as the engineers testbench following the rules and recommendations described here.

  3. Combustion chamber and thermal vapor stream producing apparatus and method

    DOEpatents

    Sperry, John S.; Krajicek, Richard W.; Cradeur, Robert R.

    1978-01-01

    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.

  4. Formation of polycyclic aromatic hydrocarbons in circumstellar envelopes

    NASA Astrophysics Data System (ADS)

    Frenklach, Michael; Feigelson, Eric D.

    1989-06-01

    Production of polycyclic aromatic hydrocarbons in carbon-rich circumstellar envelopes was investigated using a kinetic approach. A detailed chemical reaction mechanism of gas-phase PAH formation and growth, containing approximately 100 reactions of 40 species, was numerically solved under the physical conditions expected in cool stellar winds. The chemistry is based on studies of soot production in hydrocarbon pyrolysis and combustion. Several first-ring and second-ring cyclization processes were considered. A linear lumping algorithm was used to describe PAH growth beyond the second aromatic ring. PAH production using this mechanism was examined with respect to a grid of idealized constant velocity stellar winds as well as several published astrophysical models. The basic result is that the onset of PAH production in the interstellar envelopes is predicted to occur within the temperature interval of 1100 to 900 K. The absolute amounts of the PAHs formed, however, are very sensitive to a number of parameters, both chemical and astrophysical, whose values are not accurately known. Astrophysically meaningful quantities of PAHs require particularly dense and slow stellar winds and high initial acetylene abundance. It is suggested that most of the PAHs may be produced in a relatively small fraction of carbon-rich red giants.

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

    NASA Astrophysics Data System (ADS)

    Klingbeil, Adam Edgar

    tube can be used to study hydrocarbon chemistry for low-vapor-pressure compounds. The diagnostics and techniques presented here illustrate the utility and some potential applications of mid-IR laser absorption diagnostics for combustion systems.

  6. Kinetic data base for combustion modeling

    SciTech Connect

    Tsang, W.; Herron, J.T.

    1993-12-01

    The aim of this work is to develop a set of evaluated rate constants for use in the simulation of hydrocarbon combustion. The approach has been to begin with the small molecules and then introduce larger species with the various structural elements that can be found in all hydrocarbon fuels and decomposition products. Currently, the data base contains most of the species present in combustion systems with up to four carbon atoms. Thus, practically all the structural grouping found in aliphatic compounds have now been captured. The direction of future work is the addition of aromatic compounds to the data base.

  7. Apparatus for hydrocarbon extraction

    DOEpatents

    Bohnert, George W.; Verhulst, Galen G.

    2013-03-19

    Systems and methods for hydrocarbon extraction from hydrocarbon-containing material. Such systems and methods relate to extracting hydrocarbon from hydrocarbon-containing material employing a non-aqueous extractant. Additionally, such systems and methods relate to recovering and reusing non-aqueous extractant employed for extracting hydrocarbon from hydrocarbon-containing material.

  8. Combustion engine. [for air pollution control

    NASA Technical Reports Server (NTRS)

    Houseman, J. (Inventor)

    1977-01-01

    An arrangement for an internal combustion engine is provided in which one or more of the cylinders of the engine are used for generating hydrogen rich gases from hydrocarbon fuels, which gases are then mixed with air and injected into the remaining cylinders to be used as fuel. When heavy load conditions are encountered, hydrocarbon fuel may be mixed with the hydrogen rich gases and air and the mixture is then injected into the remaining cylinders as fuel.

  9. In-Cylinder Reaction Chemistry and Kinetics During Negative Valve Overlap Fuel Injection Under Low-Oxygen Conditions

    SciTech Connect

    Kalaskar, Vickey B; Szybist, James P; Splitter, Derek A; Pihl, Josh A; Gao, Zhiming; Daw, C Stuart

    2013-01-01

    Fuel injection into the negative valve overlap (NVO) period is a common method for controlling combustion phasing in homogeneous charge compression ignition (HCCI) as well as other forms of advanced combustion. During this event, at least a portion of the fuel hydrocarbons can be converted to products containing significant levels of H2 and CO, as well as other short chain hydrocarbons by means of thermal cracking, water-gas shift, and partial oxidation reactions, depending on the availability of oxygen and the time-temperature-pressure history. The resulting products alter the autoignition properties of the combined fuel mixture for HCCI. Fuel-rich chemistry in a partial oxidation environment is also relevant to other high efficiency engine concepts (e.g., the dedicated EGR (D-EGR) concept from SWRI). In this study, we used a unique 6-stroke engine cycle to experimentally investigate the chemistry of a range of fuels injected during NVO under low oxygen conditions. Fuels investigated included iso-octane, iso-butanol, ethanol, and methanol. Products from NVO chemistry were highly dependent on fuel type and injection timing, with iso-octane producing less than 1.5% hydrogen and methanol producing more than 8%. We compare the experimental trends with CHEMKIN (single zone, 0-D model) predictions using multiple kinetic mechanisms available in the current literature. Our primary conclusion is that the kinetic mechanisms investigated are unable to accurately predict the magnitude and trends of major species we observed.

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

    SciTech Connect

    Dryer, F.L.; Brezinsky, K.

    1989-07-01

    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.

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

    SciTech Connect

    Gusinow, M.A.

    1980-09-01

    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.

  12. Combustion of droplets and sprays

    NASA Astrophysics Data System (ADS)

    Eigenbrod, Christian; Sattelmayer, Thomas; Bäßler, Stefan; Mauss, Fabian; Meisl, Jürgen; Oomens, Bas; Rackwitz, Leif; Tait, Nigel; Angelberger, Christian; Eilts, Peter; Magnusson, Ingemar; Lauvergne, Romain; Tatschl, Reinhard

    2005-10-01

    The combustion of liquid hydrocarbon fuels in internal combustion engines and gas turbines for energy production and aircraft propulsion is intrinsically tied to the formation of pollutants. Apart from aiming for the highest combustion efficiencies in order to lower the operational costs and the emission of CO2, the reduction of poisonous and environmentally harmful exhaust constituents is a challenging task for scientists and engineers. The most prominent pollutants are soot, identified to trigger respiratory diseases and cancer, and nitric oxides such as NO and NO2, which promote the formation of ozone affecting the cardiovascular system when released in the lower atmosphere. Soot and nitric oxides are greenhouse pollutants in the upper atmosphere. Even though only 2-3% of the anthropogenic emission of nitric oxides are contributed by aircraft, it is the only emission at high altitudes. Unfortunately, it has the greatest impact on climate there and it does not matter whether the fuels are fossil or, in the future, biomass.

  13. Free-radicals aided combustion with scramjet applications

    NASA Technical Reports Server (NTRS)

    Yang, Yongsheng; Kumar, Ramohalli

    1992-01-01

    Theoretical and experimental investigations aimed at altering 'nature-prescribed' combustion rates in hydrogen/hydrocarbon reactions with (enriched) air are presented. The intent is to anchor flame zones in supersonic streams, and to ensure proper and controllable complete combustion in scramjets. The diagnostics are nonintrusive through IR thermograms and acoustic emissions in the control and free-radicals altered flame zones.

  14. Low NOx combustion using cogenerated oxygen and nitrogen streams

    DOEpatents

    Kobayashi, Hisashi; Bool, Lawrence E.; Snyder, William J.

    2009-02-03

    Combustion of hydrocarbon fuel is achieved with less formation of NOx by feeding the fuel into a slightly oxygen-enriched atmosphere, and separating air into oxygen-rich and nitrogen-rich streams which are fed separately into the combustion device.

  15. Combustion detector

    NASA Technical Reports Server (NTRS)

    Trimpi, R. L.; Nealy, J. E.; Grose, W. L. (Inventor)

    1973-01-01

    A device has been developed for generating a rapid response signal upon the radiation-emitting combustion reaction of certain gases in order to provide a means for the detection and identification of such reaction and concurrently discriminate against spurious signals. This combustion might be the first stage of a coal mine explosion process, and thereby this device could provide a warning of the impending explosion in time to initiate quenching action. This device has the capability of distinguishing between the light emitted from a combustion reaction and the light emitted by miners' lamps, electric lamps, welding sparks or other spurious events so that the quenching mechanism is triggered only when an explosion-initiating combustion occurs.

  16. Handbook of infrared radiation from combustion gases

    NASA Technical Reports Server (NTRS)

    Ludwig, C. B.; Malkmus, W.; Reardon, J. E.; Thomson, J. A. L.; Goulard, R. (Editor)

    1973-01-01

    The treatment of radiant emission and absorption by combustion gases are discussed. Typical applications include: (1) rocket combustion chambers and exhausts, (2) turbojet engines and exhausts, and (3) industrial furnaces. Some mention is made of radiant heat transfer problems in planetary atmospheres, in stellar atmospheres, and in reentry plasmas. Particular consideration is given to the temperature range from 500K to 3000K and the pressure range from 0.001 atmosphere to 30 atmospheres. Strong emphasis is given to the combustion products of hydrocarbon fuels with oxygen, specifically to carbon dioxide, water vapor, and carbon monoxide. In addition, species such as HF, HC1, CN, OH, and NO are treated.

  17. Combustion physics

    NASA Astrophysics Data System (ADS)

    Jones, A. R.

    1985-11-01

    Over 90% of our energy comes from combustion. By the year 2000 the figure will still be 80%, even allowing for nuclear and alternative energy sources. There are many familiar examples of combustion use, both domestic and industrial. These range from the Bunsen burner to large flares, from small combustion chambers, such as those in car engines, to industrial furnaces for steel manufacture or the generation of megawatts of electricity. There are also fires and explosions. The bountiful energy release from combustion, however, brings its problems, prominent among which are diminishing fuel resources and pollution. Combustion science is directed towards finding ways of improving efficiency and reducing pollution. One may ask, since combustion is a chemical reaction, why physics is involved: the answer is in three parts. First, chemicals cannot react unless they come together. In most flames the fuel and air are initially separate. The chemical reaction in the gas phase is very fast compared with the rate of mixing. Thus, once the fuel and air are mixed the reaction can be considered to occur instantaneously and fluid mechanics limits the rate of burning. Secondly, thermodynamics and heat transfer determine the thermal properties of the combustion products. Heat transfer also plays a role by preheating the reactants and is essential to extracting useful work. Fluid mechanics is relevant if work is to be performed directly, as in a turbine. Finally, physical methods, including electric probes, acoustics, optics, spectroscopy and pyrometry, are used to examine flames. The article is concerned mainly with how physics is used to improve the efficiency of combustion.

  18. Initiation Chemistries in Hydrocarbon (Aut)Oxidation.

    PubMed

    Sandhiya, Lakshmanan; Zipse, Hendrik

    2015-09-28

    For the (aut)oxidation of toluene to benzyl hydroperoxide, benzyl alcohol, benzaldehyde, and benzoic acid, the thermochemical profiles for various radical-generating reactions have been compared. A key intermediate in all of these reactions is benzyl hydroperoxide, the heat of formation of which has been estimated by using results from CBS-QB3, G4, and G3B3 calculations. Homolytic O-O bond cleavage in this hydroperoxide is strongly endothermic and thus unlikely to contribute significantly to initiation processes. In terms of reaction enthalpies the most favorable initiation process involves bimolecular reaction of benzyl hydroperoxide to yield hydroxy and benzyloxy radicals along with water and benzaldehyde. The reaction enthalpy and free energy of this process is significantly more favorable than those for the unimolecular dissociation of known radical initiators, such as dibenzoylperoxide or dibenzylhyponitrite. PMID:26376332

  19. Toward Solar Fuels: Photocatalytic Conversion of Carbon Dioxide to Hydrocarbons

    SciTech Connect

    Roy, SC; Varghese, OK; Paulose, M; Grimes, CA

    2010-03-01

    The past several decades have seen a significant rise in atmospheric carbon dioxide levels resulting from the combustion of hydrocarbon fuels. A solar energy based technology to recycle carbon dioxide into readily transportable hydrocarbon fuel (i.e., a solar fuel) would help reduce atmospheric CO2 levels and partly fulfill energy demands within the present hydrocarbon based fuel infrastructure. We review the present status of carbon dioxide conversion techniques, with particular attention to a recently developed photocatalytic process to convert carbon dioxide and water vapor into hydrocarbon fuels using sunlight.

  20. Hydrocarbon and nonhydrocarbon derivatives of cyclopropane

    NASA Technical Reports Server (NTRS)

    Slabey, Vernon A; Wise, Paul H; Gibbons, Louis C

    1953-01-01

    The methods used to prepare and purify 19 hydrocarbon derivatives of cyclopropane are discussed. Of these hydrocarbons, 13 were synthesized for the first time. In addition to the hydrocarbons, six cyclopropylcarbinols, five alkyl cyclopropyl ketones, three cyclopropyl chlorides, and one cyclopropanedicarboxylate were prepared as synthesis intermediates. The melting points, boiling points, refractive indices, densities, and, in some instances, heats of combustion of both the hydrocarbon and nonhydrocarbon derivatives of cyclopropane were determined. These data and the infrared spectrum of each of the 34 cyclopropane compounds are presented in this report. The infrared absorption bands characteristic of the cyclopropyl ring are discussed, and some observations are made on the contribution of the cyclopropyl ring to the molecular refractions of cyclopropane compounds.

  1. Size-extensivity-corrected multireference configuration interaction schemes to accurately predict bond dissociation energies of oxygenated hydrocarbons

    SciTech Connect

    Oyeyemi, Victor B.; Krisiloff, David B.; Keith, John A.; Libisch, Florian; Pavone, Michele; Carter, Emily A.

    2014-01-28

    Oxygenated hydrocarbons play important roles in combustion science as renewable fuels and additives, but many details about their combustion chemistry remain poorly understood. Although many methods exist for computing accurate electronic energies of molecules at equilibrium geometries, a consistent description of entire combustion reaction potential energy surfaces (PESs) requires multireference correlated wavefunction theories. Here we use bond dissociation energies (BDEs) as a foundational metric to benchmark methods based on multireference configuration interaction (MRCI) for several classes of oxygenated compounds (alcohols, aldehydes, carboxylic acids, and methyl esters). We compare results from multireference singles and doubles configuration interaction to those utilizing a posteriori and a priori size-extensivity corrections, benchmarked against experiment and coupled cluster theory. We demonstrate that size-extensivity corrections are necessary for chemically accurate BDE predictions even in relatively small molecules and furnish examples of unphysical BDE predictions resulting from using too-small orbital active spaces. We also outline the specific challenges in using MRCI methods for carbonyl-containing compounds. The resulting complete basis set extrapolated, size-extensivity-corrected MRCI scheme produces BDEs generally accurate to within 1 kcal/mol, laying the foundation for this scheme's use on larger molecules and for more complex regions of combustion PESs.

  2. Size-extensivity-corrected multireference configuration interaction schemes to accurately predict bond dissociation energies of oxygenated hydrocarbons.

    PubMed

    Oyeyemi, Victor B; Krisiloff, David B; Keith, John A; Libisch, Florian; Pavone, Michele; Carter, Emily A

    2014-01-28

    Oxygenated hydrocarbons play important roles in combustion science as renewable fuels and additives, but many details about their combustion chemistry remain poorly understood. Although many methods exist for computing accurate electronic energies of molecules at equilibrium geometries, a consistent description of entire combustion reaction potential energy surfaces (PESs) requires multireference correlated wavefunction theories. Here we use bond dissociation energies (BDEs) as a foundational metric to benchmark methods based on multireference configuration interaction (MRCI) for several classes of oxygenated compounds (alcohols, aldehydes, carboxylic acids, and methyl esters). We compare results from multireference singles and doubles configuration interaction to those utilizing a posteriori and a priori size-extensivity corrections, benchmarked against experiment and coupled cluster theory. We demonstrate that size-extensivity corrections are necessary for chemically accurate BDE predictions even in relatively small molecules and furnish examples of unphysical BDE predictions resulting from using too-small orbital active spaces. We also outline the specific challenges in using MRCI methods for carbonyl-containing compounds. The resulting complete basis set extrapolated, size-extensivity-corrected MRCI scheme produces BDEs generally accurate to within 1 kcal/mol, laying the foundation for this scheme's use on larger molecules and for more complex regions of combustion PESs. PMID:25669533

  3. Size-extensivity-corrected multireference configuration interaction schemes to accurately predict bond dissociation energies of oxygenated hydrocarbons

    NASA Astrophysics Data System (ADS)

    Oyeyemi, Victor B.; Krisiloff, David B.; Keith, John A.; Libisch, Florian; Pavone, Michele; Carter, Emily A.

    2014-01-01

    Oxygenated hydrocarbons play important roles in combustion science as renewable fuels and additives, but many details about their combustion chemistry remain poorly understood. Although many methods exist for computing accurate electronic energies of molecules at equilibrium geometries, a consistent description of entire combustion reaction potential energy surfaces (PESs) requires multireference correlated wavefunction theories. Here we use bond dissociation energies (BDEs) as a foundational metric to benchmark methods based on multireference configuration interaction (MRCI) for several classes of oxygenated compounds (alcohols, aldehydes, carboxylic acids, and methyl esters). We compare results from multireference singles and doubles configuration interaction to those utilizing a posteriori and a priori size-extensivity corrections, benchmarked against experiment and coupled cluster theory. We demonstrate that size-extensivity corrections are necessary for chemically accurate BDE predictions even in relatively small molecules and furnish examples of unphysical BDE predictions resulting from using too-small orbital active spaces. We also outline the specific challenges in using MRCI methods for carbonyl-containing compounds. The resulting complete basis set extrapolated, size-extensivity-corrected MRCI scheme produces BDEs generally accurate to within 1 kcal/mol, laying the foundation for this scheme's use on larger molecules and for more complex regions of combustion PESs.

  4. Apparatus for photocatalytic destruction of internal combustion engine emissions during cold start

    DOEpatents

    Janata, Jiri; McVay, Gary L.; Peden, Charles H.; Exarhos, Gregory J.

    1998-01-01

    A method and apparatus for the destruction of emissions from an internal combustion engine wherein a substrate coated with TiO.sub.2 is exposed to a light source in the exhaust system of an internal combustion engine thereby catalyzing oxidation/reduction reactions between gaseous hydrocarbons, carbon monoxide, nitrogen oxides and oxygen in the exhaust of the internal combustion engine.

  5. Plasma Assisted Combustion: Fundamental Studies and Engine Applications

    NASA Astrophysics Data System (ADS)

    Lefkowitz, Joseph K.

    Successful and efficient ignition in short residence time environments or ultra-lean mixtures is a key technological challenge for the evolution of advanced combustion devices in terms of both performance and efficiency. To meet this challenge, interest in plasma assisted combustion (PAC) has expanded over the past 20 years. However, understanding of the underlying physical processes of ignition by plasma discharge remains elementary. In order to shed light on the key processes involved, two main thrusts of research were undertaken in this dissertation. First, demonstration of the applicability of plasma discharges in engines and engine-like environments was carried out using a microwave discharge and a nanosecond repetitively pulsed discharge in an internal combustion engine and a pulsed detonation engine, respectively. Major conclusions include the extension of lean ignition limits for both engines, significant reduction of ignition time for mixtures with large minimum ignition energy, and the discovery of the inter-pulse coupling effect of nanosecond repetitively pulsed (NRP) discharges at high frequency. In order to understand the kinetic processes that led to these improvements, the second thrust of research directly explored the chemical kinetic processes of plasma discharges with hydrocarbon fuels. For this purpose, a low pressure flow reactor with a NRP dielectric barrier discharge cell was assembled. The discharge cell was fitted with a Herriott type multipass mirror arrangement, which allowed quantitative laser absorption spectroscopy to be performed in situ during the plasma discharge. Experiments on methane and ethylene mixtures with oxygen, argon, and helium revealed the importance of low temperature oxidation pathways in PAC. In particular, oxygen addition reactions were shown to be of primary importance in the oxidation of these small hydrocarbons in the temperature range of 300-600 K. Kinetic modeling tools, including both a coupled plasma and

  6. Sandia Combustion Research Program: Annual report, 1986

    SciTech Connect

    Not Available

    1986-01-01

    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.

  7. Chemical kinetics and combustion modeling

    SciTech Connect

    Miller, J.A.

    1993-12-01

    The goal of this program is to gain qualitative insight into how pollutants are formed in combustion systems and to develop quantitative mathematical models to predict their formation rates. The approach is an integrated one, combining low-pressure flame experiments, chemical kinetics modeling, theory, and kinetics experiments to gain as clear a picture as possible of the process in question. These efforts are focused on problems involved with the nitrogen chemistry of combustion systems and on the formation of soot and PAH in flames.

  8. Formation of polycyclic aromatic hydrocarbons from bimolecular reactions of phenyl radicals at high temperatures.

    PubMed

    Constantinidis, P; Schmitt, H-C; Fischer, I; Yan, B; Rijs, A M

    2015-11-21

    The self-reaction of the phenyl radical is one of the key reactions in combustion chemistry. Here we study this reaction in a high-temperature flow reactor by IR/UV ion dip spectroscopy, using free electron laser radiation as mid-infrared source. We identified several major reaction products based on their infrared spectra, among them indene, 1,2-dihydronaphthalene, naphthalene, biphenyl and para-terphenyl. Due to the structural sensitivity of the method, the reaction products were identified isomer-selectively. The work shows that the formation of indene and naphthalene, which was previously considered to be evidence for the HACA (hydrogen abstraction C2H2 addition) mechanism in the formation of polycyclic aromatic hydrocarbons and soot can also be understood in a phenyl addition model. PMID:26457393

  9. Plasma Chemical Aspects Of Dust Formation In Hydrocarbon Plasmas

    SciTech Connect

    Berndt, J.; Kovacevic, E.; Stepanovic, O.; Stefanovic, I.; Winter, J.

    2008-09-07

    This contribution deals with some plasma chemical aspects of dust formation in hydrocarbon plasmas. The interplay between dust formation and plasma chemistry will be discussed by means of different experimental results. One specific example concerns the formation of benzene and the role of atomic hydrogen for plasma chemical processes and dust formation in hydrocarbon discharges.

  10. Advanced Chemistry Basins Model

    SciTech Connect

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

    2002-11-10

    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.

  11. Biofuels combustion*

    DOE PAGESBeta

    Westbrook, Charles K.

    2013-01-04

    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 acidsmore » and used primarily to replace or supplement conventional diesel fuels. As a result, research efforts on so-called second- and third-generation biofuels are discussed briefly.« less

  12. Biofuels Combustion

    NASA Astrophysics Data System (ADS)

    Westbrook, Charles K.

    2013-04-01

    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.

  13. Biofuels combustion*

    SciTech Connect

    Westbrook, Charles K.

    2013-01-04

    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. As a result, research efforts on so-called second- and third-generation biofuels are discussed briefly.

  14. Bubble Combustion

    NASA Technical Reports Server (NTRS)

    Corrigan, Jackie

    2004-01-01

    A method of energy production that is capable of low pollutant emissions is fundamental to one of the four pillars of NASA s Aeronautics Blueprint: Revolutionary Vehicles. Bubble combustion, a new engine technology currently being developed at Glenn Research Center promises to provide low emissions combustion in support of NASA s vision under the Emissions Element because it generates power, while minimizing the production of carbon dioxide (CO2) and nitrous oxides (NOx), both known to be Greenhouse gases. and allows the use of alternative fuels such as corn oil, low-grade fuels, and even used motor oil. Bubble combustion is analogous to the inverse of spray combustion: the difference between bubble and spray combustion is that spray combustion is spraying a liquid in to a gas to form droplets, whereas bubble combustion involves injecting a gas into a liquid to form gaseous bubbles. In bubble combustion, the process for the ignition of the bubbles takes place on a time scale of less than a nanosecond and begins with acoustic waves perturbing each bubble. This perturbation causes the local pressure to drop below the vapor pressure of the liquid thus producing cavitation in which the bubble diameter grows, and upon reversal of the oscillating pressure field, the bubble then collapses rapidly with the aid of the high surface tension forces acting on the wall of the bubble. The rapid and violent collapse causes the temperatures inside the bubbles to soar as a result of adiabatic heating. As the temperatures rise, the gaseous contents of the bubble ignite with the bubble itself serving as its own combustion chamber. After ignition, this is the time in the bubble s life cycle where power is generated, and CO2, and NOx among other species, are produced. However, the pollutants CO2 and NOx are absorbed into the surrounding liquid. The importance of bubble combustion is that it generates power using a simple and compact device. We conducted a parametric study using CAVCHEM

  15. Modeling of Plasma Assisted Combustion

    NASA Astrophysics Data System (ADS)

    Akashi, Haruaki

    2012-10-01

    Recently, many experimental study of plasma-assisted combustion has been done. However, numerous complex reactions in combustion of hydrocarbons are preventing from theoritical study for clarifying inside the plasma-assisted combustion, and the effect of plasma-assist is still not understood. Shinohara and Sasaki [1,2] have reported that the shortening of flame length by irradiating microwave without increase of gas temperature. And they also reported that the same phenomena would occur when applying dielectric barrier discharges to the flame using simple hydrocarbon, methane. It is suggested that these phenomena may result by the electron heating. To clarify this phenomena, electron behavior under microwave and DBD was examined. For the first step of DBD plasma-assisted combustion simulation, electron Monte Carlo simulation in methane, oxygen and argon mixture gas(0.05:0.14:0.81) [2] has been done. Electron swarm parameters are sampled and electron energy distribution function (EEDF)s are also determined. In the combustion, gas temperature is higher(>1700K), so reduced electric field E/N becomes relatively high(>10V/cm/Torr). The electrons are accelerated to around 14 eV. This result agree with the optical emission from argon obtained by the experiment of reference [2]. Dissociation frequency of methane and oxygens are obtained in high. This might be one of the effect of plasma-assist. And it is suggested that the electrons should be high enough to dissociate methane, but plasma is not needed.[4pt] [1] K. Shinohara et al, J. Phys. D:Appl. Phys., 42, 182008 (1-7) (2009).[0pt] [2] K. Sasaki, 64th Annual Gaseous Electronic Conference, 56, 15 CT3.00001(2011).

  16. Prediction of flame velocities of hydrocarbon flames

    NASA Technical Reports Server (NTRS)

    Dugger, Gordon L; Simon, Dorothy M

    1954-01-01

    The laminar-flame-velocity data previously reported by the Lewis Laboratory are surveyed with respect to the correspondence between experimental flame velocities and values predicted by semitheoretical and empirical methods. The combustible mixture variables covered are hydrocarbon structure (56 hydrocarbons), equivalence ratio of fuel-air mixture, mole fraction of oxygen in the primary oxygen-nitrogen mixture (0.17 to 0.50), and initial mixture temperature (200 degrees to 615 degrees k). The semitheoretical method of prediction considered are based on three approximate theoretical equations for flame velocity: the Semenov equation, the Tanford-Pease equation, and the Manson equation.

  17. Advanced Chemistry Basins Model

    SciTech Connect

    Blanco, Mario; Cathles, Lawrence; Manhardt, Paul; Meulbroek, Peter; Tang, Yongchun

    2003-02-13

    The objective of this project is to: (1) Develop a database of additional and better maturity indicators for paleo-heat flow calibration; (2) Develop maturation models capable of predicting the chemical composition of hydrocarbons produced by a specific kerogen as a function of maturity, heating rate, etc.; assemble a compositional kinetic database of representative kerogens; (3) Develop a 4 phase equation of state-flash model that can define the physical properties (viscosity, density, etc.) of the products of kerogen maturation, and phase transitions that occur along secondary migration pathways; (4) Build a conventional basin model and incorporate new maturity indicators and data bases in a user-friendly way; (5) Develop an algorithm which combines the volume change and viscosities of the compositional maturation model to predict the chemistry of the hydrocarbons that will be expelled from the kerogen to the secondary migration pathways; (6) Develop an algorithm that predicts the flow of hydrocarbons along secondary migration pathways, accounts for mixing of miscible hydrocarbon components along the pathway, and calculates the phase fractionation that will occur as the hydrocarbons move upward down the geothermal and fluid pressure gradients in the basin; and (7) Integrate the above components into a functional model implemented on a PC or low cost workstation.

  18. Method of treating emissions of a hybrid vehicle with a hydrocarbon absorber and a catalyst bypass system

    DOEpatents

    Roos, Bryan Nathaniel; Gonze, Eugene V; Santoso, Halim G; Spohn, Brian L

    2014-01-14

    A method of treating emissions from an internal combustion engine of a hybrid vehicle includes directing a flow of air created by the internal combustion engine when the internal combustion engine is spinning but not being fueled through a hydrocarbon absorber to collect hydrocarbons within the flow of air. When the hydrocarbon absorber is full and unable to collect additional hydrocarbons, the flow of air is directed through an electrically heated catalyst to treat the flow of air and remove the hydrocarbons. When the hydrocarbon absorber is not full and able to collect additional hydrocarbons, the flow of air is directed through a bypass path that bypasses the electrically heated catalyst to conserve the thermal energy stored within the electrically heated catalyst.

  19. Addition agents effects on hydrocarbon fuels burning

    NASA Astrophysics Data System (ADS)

    Larionov, V. M.; Mitrofanov, G. A.; Sakhovskii, A. V.

    2016-01-01

    Literature review on addition agents effects on hydrocarbon fuels burning has been conducted. The impact results in flame pattern and burning velocity change, energy efficiency increase, environmentally harmful NOx and CO emission reduction and damping of self-oscillations in flow. An assumption about water molecules dissociation phenomenon existing in a number of practical applications and being neglected in most explanations for physical- chemical processes taking place in case of injection of water/steam into combustion zone has been noted. The hypothesis about necessity of water dissociation account has been proposed. It can be useful for low temperature combustion process control and NOx emission reduction.

  20. Mechanisms of Hydrocarbon Based Polymer Etch

    NASA Astrophysics Data System (ADS)

    Lane, Barton; Ventzek, Peter; Matsukuma, Masaaki; Suzuki, Ayuta; Koshiishi, Akira

    2015-09-01

    Dry etch of hydrocarbon based polymers is important for semiconductor device manufacturing. The etch mechanisms for oxygen rich plasma etch of hydrocarbon based polymers has been studied but the mechanism for lean chemistries has received little attention. We report on an experimental and analytic study of the mechanism for etching of a hydrocarbon based polymer using an Ar/O2 chemistry in a single frequency 13.56 MHz test bed. The experimental study employs an analysis of transients from sequential oxidation and Ar sputtering steps using OES and surface analytics to constrain conceptual models for the etch mechanism. The conceptual model is consistent with observations from MD studies and surface analysis performed by Vegh et al. and Oehrlein et al. and other similar studies. Parameters of the model are fit using published data and the experimentally observed time scales.

  1. Evaluation of combustion by-products of MTBE as a component of reformulated gasoline.

    PubMed

    Franklin, P M; Koshland, C P; Lucas, D; Sawyer, R F

    2001-01-01

    Methyl tertiary-butyl ether (MTBE) is a gasoline oxygenate that is widely used throughout the US and Europe as an octane-booster and as a means of reducing automotive carbon monoxide (CO) emissions. The combustion by-products of pure MTBE have been evaluated in previous laboratory studies, but little attention has been paid to the combustion by-products of MTBE as a component of gasoline. MTBE is often used in reformulated gasoline (RFG), which has chemical and physical characteristics distinct from conventional gasoline. The formation of MTBE by-products in RFG is not well-understood, especially under "worst-case" vehicle emission scenarios such as fuel-rich operations, cold-starts or malfunctioning emission control systems, conditions which have not been studied extensively. Engine-out automotive dynamometer studies have compared RFG with MTBE to non-oxygenated RFG. Their findings suggest that adding MTBE to reformulated gasoline does not impact the high temperature flame chemistry in cylinder combustion processes. Comparison of tailpipe and exhaust emission studies indicate that reactions in the catalytic converter are quite effective in destroying most hydrocarbon MTBE by-product species. Since important reaction by-products are formed in the post-flame region, understanding changes in this region will contribute to the understanding of fuel-related changes in emissions. PMID:11219713

  2. Turbulent combustion

    SciTech Connect

    Talbot, L.; Cheng, R.K.

    1993-12-01

    Turbulent combustion is the dominant process in heat and power generating systems. Its most significant aspect is to enhance the burning rate and volumetric power density. Turbulent mixing, however, also influences the chemical rates and has a direct effect on the formation of pollutants, flame ignition and extinction. Therefore, research and development of modern combustion systems for power generation, waste incineration and material synthesis must rely on a fundamental understanding of the physical effect of turbulence on combustion to develop theoretical models that can be used as design tools. The overall objective of this program is to investigate, primarily experimentally, the interaction and coupling between turbulence and combustion. These processes are complex and are characterized by scalar and velocity fluctuations with time and length scales spanning several orders of magnitude. They are also influenced by the so-called {open_quotes}field{close_quotes} effects associated with the characteristics of the flow and burner geometries. The authors` approach is to gain a fundamental understanding by investigating idealized laboratory flames. Laboratory flames are amenable to detailed interrogation by laser diagnostics and their flow geometries are chosen to simplify numerical modeling and simulations and to facilitate comparison between experiments and theory.

  3. Numerical simulation of turbulent combustion: Scientific challenges

    NASA Astrophysics Data System (ADS)

    Ren, ZhuYin; Lu, Zhen; Hou, LingYun; Lu, LiuYan

    2014-08-01

    Predictive simulation of engine combustion is key to understanding the underlying complicated physicochemical processes, improving engine performance, and reducing pollutant emissions. Critical issues as turbulence modeling, turbulence-chemistry interaction, and accommodation of detailed chemical kinetics in complex flows remain challenging and essential for high-fidelity combustion simulation. This paper reviews the current status of the state-of-the-art large eddy simulation (LES)/prob-ability density function (PDF)/detailed chemistry approach that can address the three challenging modelling issues. PDF as a subgrid model for LES is formulated and the hybrid mesh-particle method for LES/PDF simulations is described. Then the development need in micro-mixing models for the PDF simulations of turbulent premixed combustion is identified. Finally the different acceleration methods for detailed chemistry are reviewed and a combined strategy is proposed for further development.

  4. Advanced Control Methodology for Biomass Combustion

    NASA Astrophysics Data System (ADS)

    Bjornsson, Stefan

    This thesis presents a feasibility study for a low cost sensor-based combustion control system using a predictive chemical kinetic model that captures efficiencies and pollution emissions during biomass combustion. Low cost sensor module was developed, the sensors were calibrated to measure carbon monoxide and particulate matter (PM) in combustion exhaust. Major combustion species in the exhaust of a commercial biomass furnace, operating with white oak, were measured. The species concentrations were measured using the low cost sensors and commercially available diagnostics. The low cost sensor outputs compare well with the reference instruments and the sensors can be employed to measure varying concentration of CO and particulate matter in combustion exhaust. A predictive chemical kinetic model was generated to simulate biomass processes. The model uses a four element chemical reactor network (CRN) and successfully simulates smoldering, ignition and flaming combustion events. The model agrees with concentration of CO and particulate matter from experiments. The sensors and CRN model can be integrated in a control system for biomass combustion that can potentially improve combustion efficiency and reduce emissions of particulate matter, CO and unburned hydrocarbons that have been linked to urban and rural air pollution resulting in adverse health effects.

  5. Analytical combustion/emissions research related to the NASA High-Speed Research Program

    NASA Technical Reports Server (NTRS)

    Nguyen, H. L.

    1991-01-01

    A combustion analysis program aimed at upgrading and applying advanced computer programs for gas turbine applications is discussed. 2D and 3D codes, KIVA-II and LeRC-3D, have been used to provide insight into the combustion process and combustor design. The computations performed through these codes show their capability to produce reasonable results, despite such deficiencies in the current models as accurate chemical kinetics modeling of hydrocarbon combustion and turbulence and turbulence combustion interaction modeling.

  6. Plasma chemistry and organic synthesis

    NASA Technical Reports Server (NTRS)

    Tezuka, M.

    1980-01-01

    The characteristic features of chemical reactions using low temperature plasmas are described and differentiated from those seen in other reaction systems. A number of examples of applications of plasma chemistry to synthetic reactions are mentioned. The production of amino acids by discharge reactions in hydrocarbon-ammonia-water systems is discussed, and its implications for the origins of life are mentioned.

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

    DOEpatents

    Coleman, Gerald N.; Kesse, Mary L.

    2007-10-30

    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.

  8. Estimates of Cl atom concentrations and hydrocarbon kinetic reactivity in surface air at Appledore Island, Maine (USA), during International Consortium for Atmospheric Research on Transport and Transformation/Chemistry of Halogens at the Isles of Shoals

    NASA Astrophysics Data System (ADS)

    Pszenny, Alexander A. P.; Fischer, Emily V.; Russo, Rachel S.; Sive, Barkley C.; Varner, Ruth K.

    2007-05-01

    Average hydroxyl radical (OH) to chlorine atom (Cl·) ratios ranging from 45 to 119 were determined from variability-lifetime relationships for selected nonmethane hydrocarbons (NMHC) in surface air from six different transport sectors arriving at Appledore Island, Maine, during July 2004. Multiplying these ratios by an assumed average OH concentration of 2.5 × 106 cm-3 yielded estimates of Cl· concentrations of 2.2 to 5.6 × 104 cm-3. Summed reaction rates of methane and more than 30 abundant NMHCs with OH and Cl· suggest that Cl· reactions increased the kinetic reactivity of hydrocarbons by 16% to 30% over that due to OH alone in air associated with the various transport sectors. Isoprene and other abundant biogenic alkenes were the most important hydrocarbon contributors after methane to overall kinetic reactivity.

  9. Complex Hydrocarbon Chemistry in Interstellar and Solar System Ices Revealed: A Combined Infrared Spectroscopy and Reflectron Time-of-flight Mass Spectrometry Analysis of Ethane (C2H6) and D6-Ethane (C2D6) Ices Exposed to Ionizing Radiation

    NASA Astrophysics Data System (ADS)

    Abplanalp, Matthew J.; Kaiser, Ralf I.

    2016-08-01

    The irradiation of pure ethane (C2H6/C2D6) ices at 5.5 K, under ultrahigh vacuum conditions was conducted to investigate the formation of complex hydrocarbons via interaction with energetic electrons simulating the secondary electrons produced in the track of galactic cosmic rays. The chemical modifications of the ices were monitored in situ using Fourier transform infrared spectroscopy (FTIR) and during temperature-programmed desorption via mass spectrometry exploiting a quadrupole mass spectrometer with electron impact ionization (EI-QMS) as well as a reflectron time-of-flight mass spectrometer coupled to a photoionization source (PI-ReTOF-MS). FTIR confirmed previous ethane studies by detecting six molecules: methane (CH4), acetylene (C2H2), ethylene (C2H4), the ethyl radical (C2H5), 1-butene (C4H8), and n-butane (C4H10). However, the TPD phase, along with EI-QMS, and most importantly, PI-ReTOF-MS, revealed the formation of at least 23 hydrocarbons, many for the first time in ethane ice, which can be arranged in four groups with an increasing carbon-to-hydrogen ratio: C n H2n+2 (n = 3, 4, 6, 8, 10), C n H2n (n = 3–10), {{{C}}}n{{{H}}}2n-2 (n = 3–10), and {{{C}}}n{{{H}}}2n-4 (n = 4–6). The processing of simple ethane ices is relevant to the hydrocarbon chemistry in the interstellar medium, as ethane has been shown to be a major product of methane, as well as in the outer solar system. These data reveal that the processing of ethane ices can synthesize several key hydrocarbons such as C3H4 and C4H6 isomers, which ha­ve been found to synthesize polycyclic aromatic hydrocarbons like indene (C9H8) and naphtha­lene (C10H8) in the ISM and in hydrocarbon-rich atmospheres of planets and their moons such as Titan.

  10. 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...

  11. Spherical Combustion Layer in a TNT Explosion

    SciTech Connect

    Kuhl, A L; Ferguson, R E

    2001-12-09

    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.

  12. Electrically heated particulate filter regeneration using hydrocarbon adsorbents

    DOEpatents

    Gonze, Eugene V [Pinckney, MI

    2011-02-01

    An exhaust system that processes exhaust generated by an engine is provided. The system generally includes a particulate filter (PF) that filters particulates from the exhaust wherein an upstream end of the PF receives exhaust from the engine. A grid of electrically resistive material selectively heats exhaust passing through the upstream end to initiate combustion of particulates within the PF. A hydrocarbon adsorbent coating applied to the PF releases hydrocarbons into the exhaust to increase a temperature of the combustion of the particulates within the PF.

  13. Regenerative combustion device

    DOEpatents

    West, Phillip B.

    2004-03-16

    A regenerative combustion device having a combustion zone, and chemicals contained within the combustion zone, such as water, having a first equilibrium state, and a second combustible state. Means for transforming the chemicals from the first equilibrium state to the second combustible state, such as electrodes, are disposed within the chemicals. An igniter, such as a spark plug or similar device, is disposed within the combustion zone for igniting combustion of the chemicals in the second combustible state. The combustion products are contained within the combustion zone, and the chemicals are selected such that the combustion products naturally chemically revert into the chemicals in the first equilibrium state following combustion. The combustion device may thus be repeatedly reused, requiring only a brief wait after each ignition to allow the regeneration of combustible gasses within the head space.

  14. Progress on the Combustion Integrated Rack Component of the Fluids and Combustion Facility

    NASA Technical Reports Server (NTRS)

    Weiland, Karen J.; Urban, Dave (Technical Monitor)

    1999-01-01

    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 arm 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.

  15. Advanced Combustion

    SciTech Connect

    Holcomb, Gordon R.

    2013-03-11

    The activity reported in this presentation is to provide the mechanical and physical property information needed to allow rational design, development and/or choice of alloys, manufacturing approaches, and environmental exposure and component life models to enable oxy-fuel combustion boilers to operate at Ultra-Supercritical (up to 650{degrees}C & between 22-30 MPa) and/or Advanced Ultra-Supercritical conditions (760{degrees}C & 35 MPa).

  16. Combustion instability modeling and analysis

    SciTech Connect

    Santoro, R.J.; Yang, V.; Santavicca, D.A.; Sheppard, E.J.

    1995-12-31

    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.

  17. Turbulent Combustion in SDF Explosions

    SciTech Connect

    Kuhl, A L; Bell, J B; Beckner, V E

    2009-11-12

    A heterogeneous continuum model is proposed to describe the dispersion and combustion of an aluminum particle cloud in an explosion. It combines the gas-dynamic conservation laws for the gas phase with a continuum model for the dispersed phase, as formulated by Nigmatulin. Inter-phase mass, momentum and energy exchange are prescribed by phenomenological models. It incorporates a combustion model based on the mass conservation laws for fuel, air and products; source/sink terms are treated in the fast-chemistry limit appropriate for such gasdynamic fields, along with a model for mass transfer from the particle phase to the gas. The model takes into account both the afterburning of the detonation products of the C-4 booster with air, and the combustion of the Al particles with air. The model equations were integrated by high-order Godunov schemes for both the gas and particle phases. Numerical simulations of the explosion fields from 1.5-g Shock-Dispersed-Fuel (SDF) charge in a 6.6 liter calorimeter were used to validate the combustion model. Then the model was applied to 10-kg Al-SDF explosions in a an unconfined height-of-burst explosion. Computed pressure histories are compared with measured waveforms. Differences are caused by physical-chemical kinetic effects of particle combustion which induce ignition delays in the initial reactive blast wave and quenching of reactions at late times. Current simulations give initial insights into such modeling issues.

  18. Aviation combustion toxicology: an overview.

    PubMed

    Chaturvedi, Arvind K

    2010-01-01

    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

  19. Constant-Pressure Combustion Charts Including Effects of Diluent Addition

    NASA Technical Reports Server (NTRS)

    Turner, L Richard; Bogart, Donald

    1949-01-01

    Charts are presented for the calculation of (a) the final temperatures and the temperature changes involved in constant-pressure combustion processes of air and in products of combustion of air and hydrocarbon fuels, and (b) the quantity of hydrocarbon fuels required in order to attain a specified combustion temperature when water, alcohol, water-alcohol mixtures, liquid ammonia, liquid carbon dioxide, liquid nitrogen, liquid oxygen, or their mixtures are added to air as diluents or refrigerants. The ideal combustion process and combustion with incomplete heat release from the primary fuel and from combustible diluents are considered. The effect of preheating the mixture of air and diluents and the effect of an initial water-vapor content in the combustion air on the required fuel quantity are also included. The charts are applicable only to processes in which the final mixture is leaner than stoichiometric and at temperatures where dissociation is unimportant. A chart is also included to permit the calculation of the stoichiometric ratio of hydrocarbon fuel to air with diluent addition. The use of the charts is illustrated by numerical examples.

  20. Garbage to hydrocarbon fuel conversion system

    SciTech Connect

    Gould, W.A.

    1986-07-15

    A garbage to hydrocarbon fuel conversion system is described which consists of: (a) a source of combustible garbage; (b) means for pulverizing the garbage; (c) a furnace to burn the garbage; (d) means for transporting the pulverized garbage to the furnace which comprises a motor operated worm feed automatic stoker; (e) a steam generating coil inside the furnace which supplies live steam to power a turbine which in turn powers an alternating current generator; and a condenser which returns remaining the steam to a liquid state for re-circulation through the steam generating coils; (f) means for collecting incompletely combusted waste gases from the furnace; precipitating out dust and light oil for re-combustion in the furnace; and, extracting hydrocarbon gas; where in the means for precipitating out dust and light oil for re-combustion in the furnace comprise a cottrell precipitator wherein oil from an external source is mixed with fine dust received from the exhaust port, wherein an electrostatic charge helps to precipitate the dust; a dust and light oil mixer which provides a homogeneous mixture; and, an oil burner mounted to the furnace whose heat output is supplied to the furnace to add energy thereto; and (g) means for burning trapped heavy gases and removing waste ash from the furnace for disposal.

  1. Spherical combustion clouds in explosions

    NASA Astrophysics Data System (ADS)

    Kuhl, A. L.; Bell, J. B.; Beckner, V. E.; Balakrishnan, K.; Aspden, A. J.

    2013-05-01

    This study explores the properties of spherical combustion clouds in explosions. Two cases are investigated: (1) detonation of a TNT charge and combustion of its detonation products with air, and (2) shock dispersion of aluminum powder and its combustion with air. The evolution of the blast wave and ensuing combustion cloud dynamics are studied via numerical simulations with our adaptive mesh refinement combustion code. The code solves the multi-phase conservation laws for a dilute heterogeneous continuum as formulated by Nigmatulin. Single-phase combustion (e.g., TNT with air) is modeled in the fast-chemistry limit. Two-phase combustion (e.g., Al powder with air) uses an induction time model based on Arrhenius fits to Boiko's shock tube data, along with an ignition temperature criterion based on fits to Gurevich's data, and an ignition probability model that accounts for multi-particle effects on cloud ignition. Equations of state are based on polynomial fits to thermodynamic calculations with the Cheetah code, assuming frozen reactants and equilibrium products. Adaptive mesh refinement is used to resolve thin reaction zones and capture the energy-bearing scales of turbulence on the computational mesh (ILES approach). Taking advantage of the symmetry of the problem, azimuthal averaging was used to extract the mean and rms fluctuations from the numerical solution, including: thermodynamic profiles, kinematic profiles, and reaction-zone profiles across the combustion cloud. Fuel consumption was limited to ˜ 60-70 %, due to the limited amount of air a spherical combustion cloud can entrain before the turbulent velocity field decays away. Turbulent kinetic energy spectra of the solution were found to have both rotational and dilatational components, due to compressibility effects. The dilatational component was typically about 1 % of the rotational component; both seemed to preserve their spectra as they decayed. Kinetic energy of the blast wave decayed due to the

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

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

    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.

  3. Organic chemistry on Titan

    NASA Technical Reports Server (NTRS)

    Chang, S.; Scattergood, T.; Aronowitz, S.; Flores, J.

    1979-01-01

    Features taken from various models of Titan's atmosphere are combined in a working composite model that provides environmental constraints within which different pathways for organic chemical synthesis are determined. Experimental results and theoretical modeling suggest that the organic chemistry of the satellite is dominated by two processes: photochemistry and energetic particle bombardment. Photochemical reactions of CH4 in the upper atmosphere can account for the presence of C2 hydrocarbons. Reactions initiated at various levels of the atmosphere by cosmic rays, Saturn 'wind', and solar wind particle bombardment of a CH4-N2 atmospheric mixture can account for the UV-visible absorbing stratospheric haze, the reddish appearance of the satellite, and some of the C2 hydrocarbons. In the lower atmosphere photochemical processes will be important if surface temperatures are sufficiently high for gaseous NH3 to exist. It is concluded that the surface of Titan may contain ancient or recent organic matter (or both) produced in the atmosphere.

  4. NASA Microgravity Combustion Science Program

    NASA Technical Reports Server (NTRS)

    King, Merrill K.

    1999-01-01

    Combustion has been a subject of increasingly vigorous scientific research for over a century, not surprising considering that combustion accounts for approximately 85% of the world's energy production and is a key element of many critical technologies used by contemporary society. Although combustion technology is vital to our standard of living, it also poses great challenges to maintaining a habitable environment. A major goal of combustion research is production of fundamental (foundational) knowledge that can be used in developing accurate simulations of complex combustion processes, replacing current "cut-and-try" approaches and allowing developers to improve the efficiency of combustion devices, to reduce the production of harmful emissions, and to reduce the incidence of accidental uncontrolled combustion. With full understanding of the physics and chemistry involved in a given combustion process, including details of the unit processes and their interactions, physically accurate models which can then be used for parametric exploration of new combustion domains via computer simulation can be developed, with possible resultant definition of radically different approaches to accomplishment of various combustion goals. Effects of gravitational forces on earth impede combustion studies more than they impede most other areas of science. The effects of buoyancy are so ubiquitous that we often do not appreciate the enormous negative impact that they have had on the rational development of combustion science. Microgravity offers potential for major gains in combustion science understanding in that it offers unique capability to establish the flow environment rather than having it dominated by uncontrollable (under normal gravity) buoyancy effects and, through this control, to extend the range of test conditions that can be studied. It cannot be emphasized too strongly that our program is dedicated to taking advantage of microgravity to untangle complications caused

  5. Safety in the Chemical Laboratory: Fire Safety and Fire Control in the Chemistry Laboratory.

    ERIC Educational Resources Information Center

    Wilbraham, A. C.

    1979-01-01

    Discusses fire safety and fire control in the chemistry laboratory. The combustion process, extinguishing equipment, extinguisher maintenance and location, and fire safety and practices are included. (HM)

  6. Ultra-lean combustion at high inlet temperatures

    NASA Technical Reports Server (NTRS)

    Anderson, D. N.

    1981-01-01

    Combustion at inlet-air temperatures of 1100 to 1250 K was studied for application to advanced automotive gas turbine engines. Combustion was initiated by the hot environment, and therefore no external ignition source was used. Combustion was stabilized without a flameholder. The tests were performed in a 12-cm-diameter test section at a pressure of 250,000 Pa, with reference velocities of 32 to 60 m/s and at maximum combustion temperatures of 1350 to 1850 K. Number 2 diesel fuel was injected by means of a multiple-source fuel injector. Unburned hydrocarbon emissions were negligible for all test conditions. Nitrogen oxide emissions were less than 1.9 g NO2/kg fuel for combustion temperatures below 1680 K. Carbon monoxide emissions were less than 16 g CO/kg fuel for combustion temperatures greater than 1600 K, inlet-air temperatures higher than 1150 K, and residence times greater than 4.3 ms.

  7. Chemical Kinetic Models for HCCI and Diesel Combustion

    SciTech Connect

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

    2008-10-30

    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.

  8. Sandia combustion research program: Annual report, 1987

    SciTech Connect

    Palmer, R.E.; Sanders, B.R.; Ivanetich, C.A.

    1988-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2009-11-01

    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.

  10. Polycyclic aromatic hydrocarbon exhaust emissions from different reformulated diesel fuels and engine operating conditions

    NASA Astrophysics Data System (ADS)

    Borrás, Esther; Tortajada-Genaro, Luis A.; Vázquez, Monica; Zielinska, Barbara

    2009-12-01

    The study of light-duty diesel engine exhaust emissions is important due to their impact on atmospheric chemistry and air pollution. In this study, both the gas and the particulate phase of fuel exhaust were analyzed to investigate the effects of diesel reformulation and engine operating parameters. The research was focused on polycyclic aromatic hydrocarbon (PAH) compounds on particulate phase due to their high toxicity. These were analyzed using a gas chromatography-mass spectrometry (GC-MS) methodology. Although PAH profiles changed for diesel fuels with low-sulfur content and different percentages of aromatic hydrocarbons (5-25%), no significant differences for total PAH concentrations were detected. However, rape oil methyl ester biodiesel showed a greater number of PAH compounds, but in lower concentrations (close to 50%) than the reformulated diesel fuels. In addition, four engine operating conditions were evaluated, and the results showed that, during cold start, higher concentrations were observed for high molecular weight PAHs than during idling cycle and that the acceleration cycles provided higher concentrations than the steady-state conditions. Correlations between particulate PAHs and gas phase products were also observed. The emission of PAH compounds from the incomplete combustion of diesel fuel depended greatly on the source of the fuel and the driving patterns.

  11. Chemical Kinetic Modeling of Biofuel Combustion

    NASA Astrophysics Data System (ADS)

    Sarathy, Subram Maniam

    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

  12. Multi-Dimensional Measurements of Combustion Species in Flame Tube and Sector Gas Turbine Combustors

    NASA Technical Reports Server (NTRS)

    Hicks, Yolanda Royce

    1996-01-01

    The higher temperature and pressure cycles of future aviation gas turbine combustors challenge designers to produce combustors that minimize their environmental impact while maintaining high operation efficiency. The development of low emissions combustors includes the reduction of unburned hydrocarbons, smoke, and particulates, as well as the reduction of oxides of nitrogen (NO(x)). In order to better understand and control the mechanisms that produce emissions, tools are needed to aid the development of combustor hardware. Current methods of measuring species within gas turbine combustors use extractive sampling of combustion gases to determine major species concentrations and to infer the bulk flame temperature. These methods cannot be used to measure unstable combustion products and have poor spatial and temporal resolution. The intrusive nature of gas sampling may also disturb the flow structure within a combustor. Planar laser-induced fluorescence (PLIF) is an optical technique for the measurement of combustion species. In addition to its non-intrusive nature, PLIF offers these advantages over gas sampling: high spatial resolution, high temporal resolution, the ability to measure unstable species, and the potential to measure combustion temperature. This thesis considers PLIF for in-situ visualization of combustion species as a tool for the design and evaluation of gas turbine combustor subcomponents. This work constitutes the first application of PLIF to the severe environment found in liquid-fueled, aviation gas turbine combustors. Technical and applied challenges are discussed. PLIF of OH was used to observe the flame structure within the post flame zone of a flame tube combustor, and within the flame zone of a sector combustor, for a variety of fuel injector configurations. OH was selected for measurement because it is a major combustion intermediate, playing a key role in the chemistry of combustion, and because its presence within the flame zone can

  13. Propellant Chemistry for CFD Applications

    NASA Technical Reports Server (NTRS)

    Farmer, R. C.; Anderson, P. G.; Cheng, Gary C.

    1996-01-01

    Current concepts for reusable launch vehicle design have created renewed interest in the use of RP-1 fuels for high pressure and tri-propellant propulsion systems. Such designs require the use of an analytical technology that accurately accounts for the effects of real fluid properties, combustion of large hydrocarbon fuel modules, and the possibility of soot formation. These effects are inadequately treated in current computational fluid dynamic (CFD) codes used for propulsion system analyses. The objective of this investigation is to provide an accurate analytical description of hydrocarbon combustion thermodynamics and kinetics that is sufficiently computationally efficient to be a practical design tool when used with CFD codes such as the FDNS code. A rigorous description of real fluid properties for RP-1 and its combustion products will be derived from the literature and from experiments conducted in this investigation. Upon the establishment of such a description, the fluid description will be simplified by using the minimum of empiricism necessary to maintain accurate combustion analyses and including such empirical models into an appropriate CFD code. An additional benefit of this approach is that the real fluid properties analysis simplifies the introduction of the effects of droplet sprays into the combustion model. Typical species compositions of RP-1 have been identified, surrogate fuels have been established for analyses, and combustion and sooting reaction kinetics models have been developed. Methods for predicting the necessary real fluid properties have been developed and essential experiments have been designed. Verification studies are in progress, and preliminary results from these studies will be presented. The approach has been determined to be feasible, and upon its completion the required methodology for accurate performance and heat transfer CFD analyses for high pressure, tri-propellant propulsion systems will be available.

  14. Gas turbine combustion and emission control

    NASA Astrophysics Data System (ADS)

    Schetter, B.

    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 considered: aero/can type combustors, silo combustors, and annular combustors. Premix and diffusion flames are discussed.

  15. Hybrid lean premixing catalytic combustion system for gas turbines

    DOEpatents

    Critchley, Ian L.

    2003-12-09

    A system and method of combusting a hydrocarbon fuel is disclosed. The system combines the accuracy and controllability of an air staging system with the ultra-low emissions achieved by catalytic combustion systems without the need for a pre-heater. The result is a system and method that is mechanically simple and offers ultra-low emissions over a wide range of power levels, fuel properties and ambient operating conditions.

  16. Fundamental spectroscopic studies of carbenes and hydrocarbon radicals

    SciTech Connect

    Gottlieb, C.A.; Thaddeus, P.

    1993-12-01

    Highly reactive carbenes and carbon-chain radicals are studied at millimeter wavelengths by observing their rotational spectra. The purpose is to provide definitive spectroscopic identification, accurate spectroscopic constants in the lowest vibrational states, and reliable structures of the key intermediates in reactions leading to aromatic hydrocarbons and soot particles in combustion.

  17. Towards a detailed soot model for internal combustion engines

    SciTech Connect

    Mosbach, Sebastian; Celnik, Matthew S.; Raj, Abhijeet; Kraft, Markus; Zhang, Hongzhi R.; Kubo, Shuichi; Kim, Kyoung-Oh

    2009-06-15

    In this work, we present a detailed model for the formation of soot in internal combustion engines describing not only bulk quantities such as soot mass, number density, volume fraction, and surface area but also the morphology and chemical composition of soot aggregates. The new model is based on the Stochastic Reactor Model (SRM) engine code, which uses detailed chemistry and takes into account convective heat transfer and turbulent mixing, and the soot formation is accounted for by SWEEP, a population balance solver based on a Monte Carlo method. In order to couple the gas-phase to the particulate phase, a detailed chemical kinetic mechanism describing the combustion of Primary Reference Fuels (PRFs) is extended to include small Polycyclic Aromatic Hydrocarbons (PAHs) such as pyrene, which function as soot precursor species for particle inception in the soot model. Apart from providing averaged quantities as functions of crank angle like soot mass, volume fraction, aggregate diameter, and the number of primary particles per aggregate for example, the integrated model also gives detailed information such as aggregate and primary particle size distribution functions. In addition, specifics about aggregate structure and composition, including C/H ratio and PAH ring count distributions, and images similar to those produced with Transmission Electron Microscopes (TEMs), can be obtained. The new model is applied to simulate an n-heptane fuelled Homogeneous Charge Compression Ignition (HCCI) engine which is operated at an equivalence ratio of 1.93. In-cylinder pressure and heat release predictions show satisfactory agreement with measurements. Furthermore, simulated aggregate size distributions as well as their time evolution are found to qualitatively agree with those obtained experimentally through snatch sampling. It is also observed both in the experiment as well as in the simulation that aggregates in the trapped residual gases play a vital role in the soot

  18. Combustion science for incineration technology

    SciTech Connect

    Wendt, J.O.L.

    1994-12-31

    The major impediments to public acceptance, of incineration as a waste disposal technology are emissions of organic compounds, dioxins, and toxic metals. Combustion science provides insight into mechanisms governing each of these three issues. It accomplishes two things: It identifies potential problems before they occur in the field, and it proposes solutions to known problems after they have occurred. In this paper, the practical relevance of combustion science to incineration technology issues is reviewed, and important gaps and needs are identified. Turbulent mixing plays a most important role in the destruction of organic wastes in practical units. Emissions of products of incomplete combustion are also more often governed by the effects of physical combustion processes on kinetics, rather than by chemical kinetics alone. For example, incinerator failure modes can arise through wayward trajectories of rogue droplets after atomization, or, in rotary kilns, through the formation of puffs, caused by the transient release of waste from containerized sorbents and subsequent incomplete mixing. Prediction of these phenomena requires a detailed knowledge of the fundamentals of turbulent reactive flows. Toxic metals are transformed in the incinerator environment, and the high temperatures can be exploited to allow these metals to be managed. Metal/sorbent chemistry at high temperature is not known, but it is important, since it can control the ultimate impact of these metals upon the environment. 48 refs., 10 figs., 1 tab.

  19. Chemistry Notes

    ERIC Educational Resources Information Center

    School Science Review, 1972

    1972-01-01

    Thirteen ideas are presented that may be of use to chemistry teachers. Topics covered include vitamin C, industrial chemistry, electrical conductivity, electrolysis, alkali metals, vibration modes infra-red, dynamic equilibrium, and some new demonstrations in gaseous combinations. (PS)

  20. Chemistry Notes

    ERIC Educational Resources Information Center

    School Science Review, 1976

    1976-01-01

    Described are eight chemistry experiments and demonstrations applicable to introductory chemistry courses. Activities include: measure of lattice enthalpy, Le Chatelier's principle, decarboxylation of soap, use of pocket calculators in pH measurement, and making nylon. (SL)

  1. Chemistry Notes.

    ERIC Educational Resources Information Center

    School Science Review, 1983

    1983-01-01

    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…

  2. ENVIRONMENTAL CHEMISTRY

    EPA Science Inventory

    Environmental chemistry is applied to estimating the exposure of ecosystems and humans to various chemical environmental stressors. Among the stressors of concern are mercury, pesticides, and arsenic. Advanced analytical chemistry techniques are used to measure these stressors ...

  3. The Fluids and Combustion Facility Combustion Integrated Rack and The Multi-User Droplet Combustion Apparatus: Microgravity Combustion Science Using A Modular Multi-User Hardware

    NASA Astrophysics Data System (ADS)

    O'Malley, T. F.; Myhre, C. A.

    2002-01-01

    The Fluids and Combustion Facility (FCF) is a multi-rack payload planned for the International Space Station that will enable the study of fluid physics and combustion science in a microgravity environment. The Combustion Integrated Rack (CIR) is one of two International Standard Payload Racks of the FCF and is being designed primarily to support combustion science experiments. It is currently in the Flight Unit Build phase. The Multi-user Droplet Combustion Apparatus (MDCA) is a multi-user facility designed to accommodate four different droplet combustion science experiments and is the first payload for CIR. MDCA is currently in the Engineering Model build phase. Launch of the CIR and MDCA is planned for 2004. The CIR will function independently until the later launch of the Fluids Integrated Rack component of the FCF. This paper provides an overview of the capabilities and the development status of the CIR and MDCA. The CIR will contain the hardware and software required to support combustion experiments in space. It will contain an optics bench, combustion chamber, fuel oxidizer and management assembly, exhaust vent system, diagnostic cameras, power, environment control system, command and data management system, and a passive rack isolation system. Additional hardware will be installed in the chamber and on the optics bench that is customized for each science investigation. The chamber insert may provide the sample holder, small ignition source, and small diagnostics such as thermocouples and radiometers. The combustion experiments that may be conducted in the FCF include, but are not limited to, the study of 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 materials synthesis. It is expected that the facility will provide most of the hardware, with a small amount of unique hardware developed for

  4. COMBUSTION RESEARCH Chapter from the Energy and Environment Division Annual Report 1980

    SciTech Connect

    Authors, Various

    1981-05-01

    Combustion research at the Lawrence Berkeley Laboratory focuses on the study of the chemical and physical processes which are important in combustion. Two areas of application dominate; the control of combustion processes to allow the utilization of new fuels while limiting pollutant formation and the reduction of fire hazards accompanying energy generation and utilization technologies. Principal program areas are the interaction of fluid-mechanical turbulence and combustion, the development and application of new physical and chemical diagnostic techniques for combustion research, pollutant formation and destruction processes, theoretical and computational modeling of combustion processes, combustion processes in engines, fire science, and fire safety. Work is reported in these areas: ENGINE COMBUSTION AND IGNITION STUDIES; COMBUSTION CHEMISTRY AND POLLUTANT FORMATION; COMBUSTION FLUID MECHANICS; and FIRE RESEARCH.

  5. Combustion instability modeling and analysis

    SciTech Connect

    Santoro, R.J.; Yang, V.; Santavicca, D.A.

    1995-10-01

    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. Clearly, the key to successful gas turbine development is based on understanding the effects of geometry and operating conditions on combustion instability, emissions (including UHC, CO and NO{sub x}) and performance. 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.

  6. Spectroscopy, Kinetics, and Dynamics of Combustion Radicals

    SciTech Connect

    Nesbitt, David J.

    2013-08-06

    Spectroscopy, kinetics and dynamics of jet cooled hydrocarbon transients relevant to the DOE combustion mission have been explored, exploiting i) high resolution IR lasers, ii) slit discharge sources for formation of jet cooled radicals, and iii) high sensitivity detection with direct laser absorption methods and near the quantum shot noise limit. What makes this combination powerful is that such transients can be made under high concentrations and pressures characteristic of actual combustion conditions, and yet with the resulting species rapidly cooled (T ≈10-15K) in the slit supersonic expansion. Combined with the power of IR laser absorption methods, this provides novel access to spectral detection and study of many critical combustion species.

  7. Integrated self-cleaning window assembly for optical transmission in combustion environments

    DOEpatents

    Kass, Michael D [Oak Ridge, TN

    2007-07-24

    An integrated window design for optical transmission in combustion environments is described. The invention consists of an integrated optical window design that prevents and removes the accumulation of carbon-based particulate matter and gaseous hydrocarbons through a combination of heat and catalysis. These windows will enable established optical technologies to be applied to combustion environments and their exhaust systems.

  8. CLUSTER CHEMISTRY

    SciTech Connect

    Muetterties, Earl L.

    1980-05-01

    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.

  9. A coupled multi-block solution procedure for spray combustion in complex geometries

    NASA Technical Reports Server (NTRS)

    Chen, Kuo-Huey; Shuen, Jian-Shun

    1993-01-01

    Turbulent spray-combusting flow in complex geometries is presently treated by a coupled implicit procedure that employs finite-rate chemistry and real gas properties for combustion, as well as the stochastic separated model for spray and a multiblock treatment for complex geometries. Illustrative numerical tests conducted encompass a steady-state nonreacting backward-facing step flow, a premixed single-phase combustion flow, and spray combustion flow in a gas turbine combustor.

  10. 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...

  11. SYNTHESIS AND BIOLOGICAL ACTIVITY OF CYCLOPENTA EPOXIDES OF PAH (POLYCYCLIC AROMATIC HYDROCARBONS) CONTAINING PERIPHERALLY FUSED CYCLOPENTA RINGS

    EPA Science Inventory

    Polycyclic aromatic hydrocarbons (PAH) containing peripherally fused cyclopenta rings have been identified in soots from many different combustion sources. Metabolism and mutagenicity studies have been reported on the series of four cyclopenta-fused isomers derived from benzanthr...

  12. Combustion Fundamentals Research

    NASA Technical Reports Server (NTRS)

    1983-01-01

    Increased emphasis is placed on fundamental and generic research at Lewis Research Center with less systems development efforts. This is especially true in combustion research, where the study of combustion fundamentals has grown significantly in order to better address the perceived long term technical needs of the aerospace industry. The main thrusts for this combustion fundamentals program area are as follows: analytical models of combustion processes, model verification experiments, fundamental combustion experiments, and advanced numeric techniques.

  13. Coal combustion science

    SciTech Connect

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

    1990-11-01

    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.

  14. Combustion technologies

    SciTech Connect

    Barsin, J.A.

    1994-12-31

    The presentation will cover the highlights of sludge, providing information as to where it comes from, projection of how much more is expected, what is sludge, what can be done with them, and finally focus in one combustion technology that can be utilized and applied to recycle sludge. The author is with Gotaverken Energy Systems Inc. where for the past 100 years they have been involved in the recovery of chemicals in chemical pulp mills. One week ago, our name was changed to Kvaerner Pulping Inc. to better reflect our present make-up which is a combination of Kamyr AB (suppliers of proprietary highly engineered totally chlorine free chemical pulp manufacturing systems, including digesters, O{sub 2} delignification systems, and bleach plant systems) and Goetaverken. Sludges that we are concerned with derive from several sources within chemical pulp mills such as: such as primary clarifier sludges, secondary clarifier sludges, and most recently those sludges derived from post consumer paper and board recycle efforts including de-inking and those from the thermal mechanical pulping processes. These sludges have been classified as non-hazardous therefore, residue can be landfilled, but the volumes involved are growing at an alarming rate.

  15. Trace Chemistry

    NASA Technical Reports Server (NTRS)

    Radhakrishnan, Krishnan; Whitefield, Philip

    1999-01-01

    , in addition, of the pressure, temperature, and velocity. A near term goal of the experimental program should be to confirm the nonlinear effects of sulfur speciation, and if present, to provide an explanation for them. It is also desirable to examine if the particulate matter retains any sulfur. The recommendation is to examine the effects on SOx production of variations in fuel-bound sulfur and aromatic content (which may affect the amount of particulates formed). These experiments should help us to understand if there is a coupling between particulate formation and SO, concentration. Similarly, any coupling with NOx can be examined either by introducing NOx into the combustion air or by using fuel-bound nitrogen. Also of immediate urgency is the need to establish and validate a detailed mechanism for sulfur oxidation/aerosol formation, whose chemistry is concluded to be homogeneous, because there is not enough surface area for heterogeneous effects. It is envisaged that this work will involve both experimental and theoretical programs. The experimental work will require, in addition to the measurements described above, fundamental studies in devices such as flow reactors and shock tubes. Complementing this effort should be modeling and theoretical activities. One impediment to the successful modeling of sulfur oxidation is the lack of reliable data for thermodynamic and transport properties for several species, such as aqueous nitric acid, sulfur oxides, and sulfuric acid. Quantum mechanical calculations are recommended as a convenient means of deriving values for these properties. Such calculations would also help establish rate constants for several important reactions for which experimental measurements are inherently fraught with uncertainty. Efforts to implement sufficiently detailed chemistry into computational fluid dynamic codes should be continued. Zero- and one-dimensional flow models are also useful vehicles for elucidating the minimal set of species and

  16. Development of efficient and accurate skeletal mechanisms for hydrocarbon fuels and kerosene surrogate

    NASA Astrophysics Data System (ADS)

    Zhong, Fengquan; Ma, Sugang; Zhang, Xinyu; Sung, Chih-Jen; Niemeyer, Kyle E.

    2015-10-01

    In this paper, the methodology of the directed relation graph with error propagation and sensitivity analysis (DRGEPSA), proposed by Niemeyer et al. (Combust Flame 157:1760-1770, 2010), and its differences to the original directed relation graph method are described. Using DRGEPSA, the detailed mechanism of ethylene containing 71 species and 395 reaction steps is reduced to several skeletal mechanisms with different error thresholds. The 25-species and 131-step mechanism and the 24-species and 115-step mechanism are found to be accurate for the predictions of ignition delay time and laminar flame speed. Although further reduction leads to a smaller skeletal mechanism with 19 species and 68 steps, it is no longer able to represent the correct reaction processes. With the DRGEPSA method, a detailed mechanism for n-dodecane considering low-temperature chemistry and containing 2115 species and 8157 steps is reduced to a much smaller mechanism with 249 species and 910 steps while retaining good accuracy. If considering only high-temperature (higher than 1000 K) applications, the detailed mechanism can be simplified to even smaller mechanisms with 65 species and 340 steps or 48 species and 220 steps. Furthermore, a detailed mechanism for a kerosene surrogate having 207 species and 1592 steps is reduced with various error thresholds and the results show that the 72-species and 429-step mechanism and the 66-species and 392-step mechanism are capable of predicting correct combustion properties compared to those of the detailed mechanism. It is well recognized that kinetic mechanisms can be effectively used in computations only after they are reduced to an acceptable size level for computation capacity and at the same time retaining accuracy. Thus, the skeletal mechanisms generated from the present work are expected to be useful for the application of kinetic mechanisms of hydrocarbons to numerical simulations of turbulent or supersonic combustion.

  17. Apparatus for photocatalytic destruction of internal combustion engine emissions during cold start

    DOEpatents

    Janata, J.; McVay, G.L.; Peden, C.H.; Exarhos, G.J.

    1998-07-14

    A method and apparatus are disclosed for the destruction of emissions from an internal combustion engine wherein a substrate coated with TiO{sub 2} is exposed to a light source in the exhaust system of an internal combustion engine thereby catalyzing oxidation/reduction reactions between gaseous hydrocarbons, carbon monoxide, nitrogen oxides and oxygen in the exhaust of the internal combustion engine. 4 figs.

  18. Contrail: A Module from Physical Chemistry On-Line Project

    ERIC Educational Resources Information Center

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

    2007-01-01

    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.

  19. Chemical kinetic modeling of exhaust hydrocarbon oxidation

    SciTech Connect

    Wu, K.C.; Hochgreb, S.; Norris, M.B. . Dept. of Mechanical Engineering)

    1995-01-01

    Numerical simulations of the oxidation of unburned hydrocarbons from spark ignition engines were made based on full-chemistry, zero-dimensional models and compared with experiments for engine-out hydrocarbons and exhaust port oxidation. Simple correlations can be drawn between calculated results for hydrocarbon oxidation half-lives in plug or stirred reactors and measured hydrocarbon emissions. the extent of reaction through the exhaust port was simulated using calculated temperature histories for each burned gas mass element leaving the cylinder, coupled to detailed chemical kinetic rate equations. The results show that, for the fuels considered, the extent of oxidation of the remaining unburned fuel measured through the exhaust can be bracketed by the calculated results for the well-mixed (average) and core (adiabatically expanded) temperatures in the exhaust. Most of the oxidation is shown to occur at the very early exhaust times. For the paraffins considered, comparisons of simulations and experiments suggest that fuel oxidation is partially controlled by the mixing of cold gases at the initial stages of exhaust, where temperatures are high and the cold unburned mixture emerges from the wall layers into the exhaust jet. These conclusions are supported by the relatively small measured dependence on fuel type of the extent of oxidation in the exhaust, and by the resulting ratio of fuel to nonfuel hydrocarbons in the exhaust port exit.

  20. Application of a non-thermal plasma to combustion enhancement.

    SciTech Connect

    Rosocha, L. A.; Kim, Y.; Stange, Sabine

    2004-01-01

    As a primary objective, researchers in Los Alamos National Laboratory's P-24 Plasma Physics group are aiming to minimize U.S. energy dependency on foreign resources through experiments incorporating a plasma assisted combustion unit. Under this broad category, researchers seek to increase efficiency and reduce NO{sub x}/SO{sub x} and unburned hydrocarbon emissions in IC-engines, gas-turbine engines, and burner units. To date, the existing lean burn operations, consisting of higher air to fuel ratio, have successfully operated in a regime where reduced NO{sub x}/SO{sub x} emissions are expected and have also shown increased combustion efficiency (less unburned hydrocarbon) for propane. By incorporating a lean burn operation assisted by a non-thermal plasma (NTP) reactor, the fracturing of hydrocarbons can occur with increased power (combustion, efficiency, and stability). Non-thermal plasma units produce energetic electrons, but avoid the high gas and ion temperatures involved in thermal plasmas. One non-thermal plasma method, known as silent discharge, allows free radicals to act in propagating combustion reactions, as well as intermediaries in hydrocarbon fracturing. Using non-thermal plasma units, researchers have developed a fuel activation/conversion system capable of decreasing pollutants while increasing fuel efficiency, providing a path toward future U.S. energy independence.

  1. Combustion 2000

    SciTech Connect

    2000-06-30

    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

  2. Combustion 2000

    SciTech Connect

    A. Levasseur; S. Goodstine; J. Ruby; M. Nawaz; C. Senior; F. Robson; S. Lehman; W. Blecher; W. Fugard; A. Rao; A. Sarofim; P. Smith; D. Pershing; E. Eddings; M. Cremer; J. Hurley; G. Weber; M. Jones; M. Collings; D. Hajicek; A. Henderson; P. Klevan; D. Seery; B. Knight; R. Lessard; J. Sangiovanni; A. Dennis; C. Bird; W. Sutton; N. Bornstein; F. Cogswell; C. Randino; S. Gale; Mike Heap

    2001-06-30

    . To achieve these objectives requires a change from complete reliance of coal-fired systems on steam turbines (Rankine cycles) and moving forward to a combined cycle utilizing gas turbines (Brayton cycles) which offer the possibility of significantly greater efficiency. This is because gas turbine cycles operate at temperatures well beyond current steam cycles, allowing the working fluid (air) temperature to more closely approach that of the major energy source, the combustion of coal. In fact, a good figure of merit for a HIPPS design is just how much of the enthalpy from coal combustion is used by the gas turbine. The efficiency of a power cycle varies directly with the temperature of the working fluid and for contemporary gas turbines the optimal turbine inlet temperature is in the range of 2300-2500 F (1260-1371 C). These temperatures are beyond the working range of currently available alloys and are also in the range of the ash fusion temperature of most coals. These two sets of physical properties combine to produce the major engineering challenges for a HIPPS design. The UTRC team developed a design hierarchy to impose more rigor in our approach. Once the size of the plant had been determined by the choice of gas turbine and the matching steam turbine, the design process of the High Temperature Advanced Furnace (HITAF) moved ineluctably to a down-fired, slagging configuration. This design was based on two air heaters: one a high temperature slagging Radiative Air Heater (RAH) and a lower temperature, dry ash Convective Air Heater (CAH). The specific details of the air heaters are arrived at by an iterative sequence in the following order:-Starting from the overall Cycle requirements which set the limits for the combustion and heat transfer analysis-The available enthalpy determined the range of materials, ceramics or alloys, which could tolerate the temperatures-Structural Analysis of the designs proved to be the major limitation-Finally the commercialization

  3. Modeling complex chemical effects in turbulent nonpremixed combustion

    NASA Technical Reports Server (NTRS)

    Smith, Nigel S. A.

    1995-01-01

    Virtually all of the energy derived from the consumption of combustibles occurs in systems which utilize turbulent fluid motion. Since combustion is largely related to the mixing of fluids and mixing processes are orders of magnitude more rapid when enhanced by turbulent motion, efficiency criteria dictate that chemically powered devices necessarily involve fluid turbulence. Where combustion occurs concurrently with mixing at an interface between two reactive fluid bodies, this mode of combustion is called nonpremixed combustion. This is distinct from premixed combustion where flame-fronts propagate into a homogeneous mixture of reactants. These two modes are limiting cases in the range of temporal lag between mixing of reactants and the onset of reaction. Nonpremixed combustion occurs where this lag tends to zero, while premixed combustion occurs where this lag tends to infinity. Many combustion processes are hybrids of these two extremes with finite non-zero lag times. Turbulent nonpremixed combustion is important from a practical standpoint because it occurs in gas fired boilers, furnaces, waste incinerators, diesel engines, gas turbine combustors, and afterburners etc. To a large extent, past development of these practical systems involved an empirical methodology. Presently, efficiency standards and emission regulations are being further tightened (Correa 1993), and empiricism has had to give way to more fundamental research in order to understand and effectively model practical combustion processes (Pope 1991). A key element in effective modeling of turbulent combustion is making use of a sufficiently detailed chemical kinetic mechanism. The prediction of pollutant emission such as oxides of nitrogen (NO(x)) and sulphur (SO(x)) unburned hydrocarbons, and particulates demands the use of detailed chemical mechanisms. It is essential that practical models for turbulent nonpremixed combustion are capable of handling large numbers of 'stiff' chemical species

  4. Monitoring of vapor phase polycyclic aromatic hydrocarbons

    DOEpatents

    Vo-Dinh, Tuan; Hajaligol, Mohammad R.

    2004-06-01

    An apparatus for monitoring vapor phase polycyclic aromatic hydrocarbons in a high-temperature environment has an excitation source producing electromagnetic radiation, an optical path having an optical probe optically communicating the electromagnetic radiation received at a proximal end to a distal end, a spectrometer or polychromator, a detector, and a positioner coupled to the first optical path. The positioner can slidably move the distal end of the optical probe to maintain the distal end position with respect to an area of a material undergoing combustion. The emitted wavelength can be directed to a detector in a single optical probe 180.degree. backscattered configuration, in a dual optical probe 180.degree. backscattered configuration or in a dual optical probe 90.degree. side scattered configuration. The apparatus can be used to monitor an emitted wavelength of energy from a polycyclic aromatic hydrocarbon as it fluoresces in a high temperature environment.

  5. A laboratory scale supersonic combustive flow system

    SciTech Connect

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

    1995-02-01

    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.

  6. 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 ...

  7. Atmospheric chemistry - Response to human influence

    NASA Technical Reports Server (NTRS)

    Logan, J. A.; Prather, M. J.; Wofsy, S. G.; Mcelroy, M. B.

    1978-01-01

    Global atmospheric chemistry is surveyed, and the agreement of models with observed distribution of gases is considered. The influence of human perturbations due to combustion, agriculture, and chloro-carbon releases is examined with emphasis on ozone. Effects of combustion-related releases of CO on the abundances of other gases as well as possible effects of CO on tropospheric ozone are discussed. Other topics include the contribution of the chlorocarbon industry to stratospheric chloride and the recombination of nitrogen fixed by agriculture and combustion.

  8. Chemistry Notes

    ERIC Educational Resources Information Center

    School Science Review, 1972

    1972-01-01

    Twelve new chemistry expermiments are described. Broad areas covered include atomic structure, solubility, gaseous diffusion, endothermic reactions, alcohols, equilibrium, atomic volumes, and some improvised apparatus. (PS)

  9. Technetium chemistry

    SciTech Connect

    Burns, C.; Bryan, J.; Cotton, F.; Ott, K.; Kubas, G.; Haefner, S.; Barrera, J.; Hall, K.; Burrell, A.

    1996-04-01

    Technetium chemistry is a young and developing field. Despite the limited knowledge of its chemistry, technetium is the workhorse for nuclear medicine. Technetium is also a significant environmental concern because it is formed as a byproduct of nuclear weapons production and fission-power generators. Development of new technetium radio-pharmaceuticals and effective environmental control depends strongly upon knowledge of basic technetium chemistry. The authors performed research into the basic coordination and organometallic chemistry of technetium and used this knowledge to address nuclear medicine and environmental applications. This is the final report of a three-year Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL).

  10. Aliphatic hydrocarbon and polycyclic aromatic hydrocarbon geochemistry of twelve major rivers in the Northwest Territories

    SciTech Connect

    Backus, S.; Swyripa, M.; Peddle, J.; Jeffries, D.S.

    1995-12-31

    Suspended sediment and water samples collected from twelve major rivers in the Northwest Territories were analyzed for aliphatic hydrocarbons and polycyclic aromatic hydrocarbons (PAHs) to assess the sources and transport of hydrocarbons entering the Arctic Ocean. Three stations on the Mackenzie River and one station near the mouth of eleven other northern rivers were selected for sampling. Samples were collected on the Mackenzie River on four occasions to characterize spring, summer and fall flow conditions and once on the remaining eleven rivers during high flow conditions. The Mackenzie River is distinctively different then the other eleven rivers. Naturally occurring hydrocarbons predominate in the river. These hydrocarbons include biogenic alkanes, diagenic PAHs, petrogenic alkanes, and PAHs from oil seeps and/or bitumens. Anthropogenic inputs of PAHs are low as indicated by low concentrations of combustion PAHs. Alkyl PAH distributions indicate that a significant component of the lower molecular weight PAH fraction is petrogenic. The majority of the high molecular weight PAHs, together with the petrogenic PAHs have a principal source in the Mackenzie River.

  11. Evolution and current understanding of physicochemical characterization of particulate matter from reactivity controlled compression ignition combustion on a multicylinder light-duty engine

    DOE PAGESBeta

    Storey, John Morse; Curran, Scott J.; Lewis, Samuel A.; Barone, Teresa L.; Dempsey, Adam B.; Moses-DeBusk, Melanie; Hanson, Reed M.; Prikhodko, Vitaly Y.; Northrop, William F.

    2016-08-04

    Low-temperature compression ignition combustion can result in nearly smokeless combustion, as indicated by a smoke meter or other forms of soot measurement that rely on absorbance due to elemental carbon content. Highly premixed low-temperature combustion modes do not form particulate matter in the traditional pathways seen with conventional diesel combustion. Previous research into reactivity controlled compression ignition particulate matter has shown, despite a near zero smoke number, significant mass can be collected on filter media used for particulate matter certification measurement. In addition, particulate matter size distributions reveal that a fraction of the particles survive heated double-dilution conditions. This papermore » summarizes research completed at Oak Ridge National Laboratory to date on characterizing the nature, chemistry and aftertreatment considerations of reactivity controlled compression ignition particulate matter and presents new research highlighting the importance of injection strategy and fuel composition on reactivity controlled compression ignition particulate matter formation. Particle size measurements and the transmission electron microscopy results do show the presence of soot particles; however, the elemental carbon fraction was, in many cases, within the uncertainty of the thermal–optical measurement. Particulate matter emitted during reactivity controlled compression ignition operation was also collected with a novel sampling technique and analyzed by thermal desorption or pyrolysis gas chromatography mass spectroscopy. Particulate matter speciation results indicated that the high boiling range of diesel hydrocarbons was likely responsible for the particulate matter mass captured on the filter media. Finally, to investigate potential fuel chemistry effects, either ethanol or biodiesel were incorporated to assess whether oxygenated fuels may enhance particle emission reduction.« less

  12. Hydrocarbon emissions and health risks from cookstoves in developing countries.

    PubMed

    Zhang, J; Smith, K R

    1996-01-01

    The nonmethane hydrocarbon emissions from several types of cookstoves commonly used in developing countries were measured in a pilot study conducted in Manila, the Philippines. Four types of fuel, i.e., wood, charcoal, kerosene, and liquefied petroleum gas (LPG), were tested. Because kerosene was burned in three different types of stoves, there were six fuel/stove combinations tested. Fifty-nine nonmethane hydrocarbons were identified frequently in emissions of these cookstoves, with emission ratios to CO2 up to 5.3 x 10(-3). The emissions were quantitated with emission factors on both a mass basis (emissions/kg fuel) and a task basis (emissions/cooking task). On a task basis, combustion of biomass fuels (wood and charcoal) generally produced higher emission factors than combustion of fossil fuels (kerosene and LPG). One type of kerosene stove (wick stove), however, still generated the greatest emissions of some individual and classes of hydrocarbons, indicating that emissions were dependent on not only fuel types but also combustion devices. Some hydrocarbons, e.g., benzene, 1,3-butadiene, styrene, and xylenes, were of concern because of their carcinogenic properties. The lifetime risk from exposures to these compounds emitted from cookstoves was tentatively estimated by using a simple exposure model and published cancer potencies. PMID:8792294

  13. Combustion 2000

    SciTech Connect

    1999-12-31

    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

  14. Dioxins and polyvinylchloride in combustion and fires.

    PubMed

    Zhang, Mengmei; Buekens, Alfons; Jiang, Xuguang; Li, Xiaodong

    2015-07-01

    This review on polyvinylchloride (PVC) and dioxins collects, collates, and compares data from selected sources on the formation of polychlorinated dibenzofurans (PCDFs) and dibenzo-p-dioxins (PCDDs), or in brief dioxins, in combustion and fires. In professional spheres, the incineration of PVC as part of municipal solid waste is seldom seen as a problem, since deep flue gas cleaning is required anyhow. Conversely, with its high content of chlorine, PVC is frequently branded as a major chlorine donor and spitefully leads to substantial formation of dioxins during poorly controlled or uncontrolled combustion and open fires. Numerous still ill-documented and diverse factors of influence may affect the formation of dioxins during combustion: on the one hand PVC-compounds represent an array of materials with widely different formulations; on the other hand these may all be exposed to fires of different nature and consequences. Hence, attention should be paid to PVC with respect to the ignition and development of fires, as well as attenuating the emission of objectionable compounds, such as carbon monoxide, hydrogen chloride, polycyclic aromatic hydrocarbons, and dioxins. This review summarises available dioxin emissions data, gathers experimental and simulation studies of fires and combustion tests involving PVC, and identifies and analyses the effects of several local factors of influence, affecting the formation of dioxins during PVC combustion. PMID:26185164

  15. Correlation of physical properties with molecular structure for some dicyclic hydrocarbons having high thermal-energy release per unit volume

    NASA Technical Reports Server (NTRS)

    Wise, P H; Serijan, K T; Goodman, I A

    1951-01-01

    As part of a program to study the correlation between molecular structure and physical properties of high-density hydrocarbons, the net heats of combustion, melting points, boiling points, densities, and kinematic viscosities of some hydrocarbons in the 2-n-alkylbiphenyl, 1,1-diphenylalkane, diphenylalkane, 1,1-dicyclohexylalkane, and dicyclohexylalkane series are presented.

  16. The combustion program at CTR

    NASA Technical Reports Server (NTRS)

    Poinsot, Thierry J.

    1993-01-01

    Understanding and modeling of turbulent combustion are key problems in the computation of numerous practical systems. Because of the lack of analytical theories in this field and of the difficulty of performing precise experiments, direct numerical simulation (DNS) appears to be one of the most attractive tools to use in addressing this problem. The general objective of DNS of reacting flows is to improve our knowledge of turbulent combustion but also to use this information for turbulent combustion models. For the foreseeable future, numerical simulation of the full three-dimensional governing partial differential equations with variable density and transport properties as well as complex chemistry will remain intractable; thus, various levels of simplification will remain necessary. On one hand, the requirement to simplify is not necessarily a handicap: numerical simulations allow the researcher a degree of control in isolating specific physical phenomena that is inaccessible in experiments. CTR has pursued an intensive research program in the field of DNS for turbulent reacting flows since 1987. DNS of reacting flows is quite different from DNS of non-reacting flows: without reaction, the equations to solve are clearly the five conservation equations of the Navier Stokes system for compressible situations (four for incompressible cases), and the limitation of the approach is the Reynolds number (or in other words the number of points in the computation). For reacting flows, the choice of the equations, the species (each species will require one additional conservation equation), the chemical scheme, and the configuration itself is more complex.

  17. Recovering hydrocarbons from hydrocarbon-containing vapors

    DOEpatents

    Mirza, Zia I.; Knell, Everett W.; Winter, Bruce L.

    1980-09-30

    Values are recovered from a hydrocarbon-containing vapor by contacting the vapor with quench liquid consisting essentially of hydrocarbons to form a condensate and a vapor residue, the condensate and quench fluid forming a combined liquid stream. The combined liquid stream is mixed with a viscosity-lowering liquid to form a mixed liquid having a viscosity lower than the viscosity of the combined liquid stream to permit easy handling of the combined liquid stream. The quench liquid is a cooled portion of the mixed liquid. Viscosity-lowering liquid is separated from a portion of the mixed liquid and cycled to form additional mixed liquid.

  18. Atmospheric Chemistry of Acenaphthalene and Acenaphthylene

    NASA Astrophysics Data System (ADS)

    Zhou, S.; Wenger, J. C.

    2009-04-01

    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

  19. Oxygenated Derivatives of Hydrocarbons

    Technology Transfer Automated Retrieval System (TEKTRAN)

    For the book entitled “Insect Hydrocarbons: Biology, Biochemistry and Chemical Ecology”, this chapter presents a comprehensive review of the occurrence, structure and function of oxygenated derivatives of hydrocarbons. The book chapter focuses on the occurrence, structural identification and functi...

  20. Hydrocarbon Spectral Database

    National Institute of Standards and Technology Data Gateway

    SRD 115 Hydrocarbon Spectral Database (Web, free access)   All of the rotational spectral lines observed and reported in the open literature for 91 hydrocarbon molecules have been tabulated. The isotopic molecular species, assigned quantum numbers, observed frequency, estimated measurement uncertainty and reference are given for each transition reported.

  1. Chemistry Notes.

    ERIC Educational Resources Information Center

    School Science Review, 1981

    1981-01-01

    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…

  2. Hydrocarbon emissions speciation in diesel and biodiesel exhausts

    NASA Astrophysics Data System (ADS)

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

    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

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

    SciTech Connect

    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

    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

  4. Properties of Combustion Gases

    NASA Technical Reports Server (NTRS)

    Wear, J. D.; Jones, R. E.; Trout, A. M.; Mcbride, B. J.

    1986-01-01

    New series of reports: First report lists data from combustion of ASTM Jet A fuel and dry air; second report presents tables and figures for combustion-gas properties of natural-gas fuel and dry air, and equivalent ratios.

  5. Source fingerprints for volatile non-methane hydrocarbons

    SciTech Connect

    Doskey, P.V. ); Porter, J.A. ); Scheff, P.A. )

    1992-11-01

    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.

  6. PDF Modeling of Turbulent Lean Premixed Combustion

    SciTech Connect

    Yilmaz, S.L.; •Givi, P.; Strakey, P.A.

    2007-10-01

    The joint velocity-scalar-frequency probability density function (PDF) methodology is employed for prediction of a bluff-body stabilized lean premixed methane-air flame. A reduced mechanism with CO and NO chemistry is used to describe fuel oxidation. The predicted mean and rms values of the velocity, temperature and concentrations of major and minor species are compared with laboratory measurements. This technical effort was performed in support of the National Energy Technology Laboratory’s on-going research in “Assessment of Turbo-Chemistry Models for Gas Turbine Combustion Emissions” under the RDS contract DE-AC26-04NT41817.

  7. Internal combustion engine with multiple combustion chambers

    SciTech Connect

    Gruenwald, D.J.

    1992-05-26

    This patent describes a two-cycle compression ignition engine. It comprises one cylinder, a reciprocable piston moveable in the cylinder, a piston connecting rod, a crankshaft for operation of the piston connecting rod, a cylinder head enclosing the cylinder, the upper surface of the piston and the enclosing surface of the cylinder head defining a cylinder clearance volume, a first combustion chamber and a second combustion chamber located in the cylinder head. This patent describes improvement in means for isolating the combustion process for one full 360{degrees} rotation of the crankshaft; wherein the combustion chambers alternatively provide for expansion of combustion products in the respective chambers into the cylinder volume near top dead center upon each revolution of the crankshaft.

  8. Maximal combustion temperature estimation

    NASA Astrophysics Data System (ADS)

    Golodova, E.; Shchepakina, E.

    2006-12-01

    This work is concerned with the phenomenon of delayed loss of stability and the estimation of the maximal temperature of safe combustion. Using the qualitative theory of singular perturbations and canard techniques we determine the maximal temperature on the trajectories located in the transition region between the slow combustion regime and the explosive one. This approach is used to estimate the maximal temperature of safe combustion in multi-phase combustion models.

  9. Turbulent Methane-Air Combustion

    NASA Technical Reports Server (NTRS)

    Yaboah, Yaw D.; Njokwe, Anny; James, LaShanda

    1996-01-01

    This study is aimed at enhancing the understanding of turbulent premixed methane-air combustion. Such understanding is essential since: (1) many industries are now pursuing lighter hydrocarbon alternative fuels and the use of premixed flames to reduce pollutant emissions, and (2) the characteristic dimensions and flow rates of most industrial combustors are often large for flows to be turbulent. The specific objectives of the study are: (1) to establish the effects of process variables (e.g., flow rate, fuel/air ratio, chlorinated hydro-carbons, and pressure) on the emissions and flow structure (velocity distribution, streamlines, vorticity and flame shape), and (2) to develop a mechanistic model to explain the observed trends. This includes the acquisition of Dantec FlowMap Particle Image Velocimeter. The design and fabrication of the premixed burner has also been completed. The study is now at the stage of testing of equipment and analytical instruments. The presentation will give details on the tasks completed and on the current and future plans. The project is progressing well and all activities are on schedule. The outlook for the success of the project is bright.

  10. Mechanisms of droplet combustion

    NASA Technical Reports Server (NTRS)

    Law, C. K.

    1982-01-01

    The fundamental physico-chemical mechanisms governing droplet vaporization and combustion are discussed. Specific topics include governing equations and simplifications, the classical d(2)-Law solution and its subsequent modification, finite-rate kinetics and the flame structure, droplet dynamics, near- and super-critical combustion, combustion of multicomponent fuel blends/emulsions/suspensions, and droplet interaction. Potential research topics are suggested.

  11. Compounds in airborne particulates - Salts and hydrocarbons. [at Cleveland, OH

    NASA Technical Reports Server (NTRS)

    King, R. B.; Antoine, A. C.; Fordyce, J. S.; Neustadter, H. E.; Leibecki, H. F.

    1977-01-01

    Concentrations of 10 polycyclic aromatic hydrocarbons (PAH), the aliphatics as a group, sulfate, nitrate, fluoride, acidity, and carbon in the airborne particulate matter were measured at 16 sites in Cleveland, OH over a 1-year period during 1971 and 1972. Analytical methods used included gas chromatography, colorimetry, and combustion techniques. Uncertainties in the concentrations associated with the sampling procedures, and the analytical methods are evaluated. The data are discussed relative to other studies and source origins. High concentrations downwind of coke ovens for 3,4 benzopyrene are discussed. Hydrocarbon correlation studies indicated no significant relations among compounds studied.

  12. Nitrogen release during coal combustion

    SciTech Connect

    Baxter, L.L.; Mitchell, R.E.; Fletcher, T.H.; Hurt, R.H.

    1995-02-01

    Experiments in entrained flow reactors at combustion temperatures are performed to resolve the rank dependence of nitrogen release on an elemental basis for a suite of 15 U.S. coals ranging from lignite to low-volatile bituminous. Data were obtained as a function of particle conversion, with overall mass loss up to 99% on a dry, ash-free basis. Nitrogen release rates are presented relative to both carbon loss and overall mass loss. During devolatilization, fractional nitrogen release from low-rank coals is much slower than fractional mass release and noticeably slower than fractional carbon release. As coal rank increases, fractional nitrogen release rate relative to that of carbon and mass increases, with fractional nitrogen release rates exceeding fractional mass and fractional carbon release rates during devolatilization for high-rank (low-volatile bituminous) coals. At the onset of combustion, nitrogen release rates increase significantly. For all coals investigated, cumulative fractional nitrogen loss rates relative to those of mass and carbon passes through a maximum during the earliest stages of oxidation. The mechanism for generating this maximum is postulated to involve nascent thermal rupture of nitrogen-containing compounds and possible preferential oxidation of nitrogen sites. During later stages of oxidation, the cumulative fractional loss of nitrogen approaches that of carbon for all coals. Changes in the relative release rates of nitrogen compared to those of both overall mass and carbon during all stages of combustion are attributed to a combination of the chemical structure of coals, temperature histories during combustion, and char chemistry.

  13. Homogeneous catalysts in hypersonic combustion

    SciTech Connect

    Harradine, D.M.; Lyman, J.L.; Oldenborg, R.C.; Pack, R.T.; Schott, G.L.

    1989-01-01

    Density and residence time both become unfavorably small for efficient combustion of hydrogen fuel in ramjet propulsion in air at high altitude and hypersonic speed. Raising the density and increasing the transit time of the air through the engine necessitates stronger contraction of the air flow area. This enhances the kinetic and thermodynamic tendency of H/sub 2/O to form completely, accompanied only by N/sub 2/ and any excess H/sub 2/(or O/sub 2/). The by-products to be avoided are the energetically expensive fragment species H and/or O atoms and OH radicals, and residual (2H/sub 2/ plus O/sub 2/). However, excessive area contraction raises air temperature and consequent combustion-product temperature by adiabatic compression. This counteracts and ultimately overwhelms the thermodynamic benefit by which higher density favors the triatomic product, H/sub 2/O, over its monatomic and diatomic alternatives. For static pressures in the neighborhood of 1 atm, static temperature must be kept or brought below ca. 2400 K for acceptable stability of H/sub 2/O. Another measure, whose requisite chemistry we address here, is to extract propulsive work from the combustion products early in the expansion. The objective is to lower the static temperature of the combustion stream enough for H/sub 2/O to become adequately stable before the exhaust flow is massively expanded and its composition ''frozen.'' We proceed to address this mechanism and its kinetics, and then examine prospects for enhancing its rate by homogeneous catalysts. 9 refs.

  14. Source term evaluation for combustion modeling

    NASA Technical Reports Server (NTRS)

    Sussman, Myles A.

    1993-01-01

    A modification is developed for application to the source terms used in combustion modeling. The modification accounts for the error of the finite difference scheme in regions where chain-branching chemical reactions produce exponential growth of species densities. The modification is first applied to a one-dimensional scalar model problem. It is then generalized to multiple chemical species, and used in quasi-one-dimensional computations of shock-induced combustion in a channel. Grid refinement studies demonstrate the improved accuracy of the method using this modification. The algorithm is applied in two spatial dimensions and used in simulations of steady and unsteady shock-induced combustion. Comparisons with ballistic range experiments give confidence in the numerical technique and the 9-species hydrogen-air chemistry model.

  15. 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...

  16. Symposium (International) on Combustion, 18th, 1980

    SciTech Connect

    Anon

    1980-08-01

    This conference proceedings contains 196 papers. 181 papers are indexed separately. Topics covered include: combustion generated pollution; propellant combustion; fluidized bed combustion; combustion of droplets and spray; premixed flame studies; fire studies; flame stabilization; coal flammability; chemical kinetics; turbulent combustion; soot; coal combustion; modeling of combustion processes; combustion diagnostics; detonations and explosions; ignition; internal combustion engines; combustion studies; and furnaces.

  17. On mathematical modelling of flameless combustion

    SciTech Connect

    Mancini, Marco; Schwoeppe, Patrick; Weber, Roman; Orsino, Stefano

    2007-07-15

    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)

  18. Circumstellar chemistry

    NASA Technical Reports Server (NTRS)

    Glassgold, Alfred E.; Huggins, Patrick J.

    1987-01-01

    The study of the outer envelopes of cool evolved stars has become an active area of research. The physical properties of CS envelopes are presented. Observations of many wavelengths bands are relevant. A summary of observations and a discussion of theoretical considerations concerning the chemistry are summarized. Recent theoretical considerations show that the thermal equilibrium model is of limited use for understanding the chemistry of the outer CS envelopes. The theoretical modeling of the chemistry of CS envelopes provides a quantitive test of chemical concepts which have a broader interest than the envelopes themselves.

  19. Ethylene oxidation chemistry in a well-stirred reactor

    SciTech Connect

    Marinov, N.; Malte, P.

    1994-09-01

    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.

  20. Method and apparatus for monitoring a hydrocarbon-selective catalytic reduction device

    DOEpatents

    Schmieg, Steven J; Viola, Michael B; Cheng, Shi-Wai S; Mulawa, Patricia A; Hilden, David L; Sloane, Thompson M; Lee, Jong H

    2014-05-06

    A method for monitoring a hydrocarbon-selective catalytic reactor device of an exhaust aftertreatment system of an internal combustion engine operating lean of stoichiometry includes injecting a reductant into an exhaust gas feedstream upstream of the hydrocarbon-selective catalytic reactor device at a predetermined mass flowrate of the reductant, and determining a space velocity associated with a predetermined forward portion of the hydrocarbon-selective catalytic reactor device. When the space velocity exceeds a predetermined threshold space velocity, a temperature differential across the predetermined forward portion of the hydrocarbon-selective catalytic reactor device is determined, and a threshold temperature as a function of the space velocity and the mass flowrate of the reductant is determined. If the temperature differential across the predetermined forward portion of the hydrocarbon-selective catalytic reactor device is below the threshold temperature, operation of the engine is controlled to regenerate the hydrocarbon-selective catalytic reactor device.

  1. 38th JANNAF Combustion Subcommittee Meeting. Volume 1

    NASA Technical Reports Server (NTRS)

    Fry, Ronald S. (Editor); Eggleston, Debra S. (Editor); Gannaway, Mary T. (Editor)

    2002-01-01

    This volume, the first of two volumes, is a collection of 55 unclassified/unlimited-distribution papers which were presented at the Joint Army-Navy-NASA-Air Force (JANNAF) 38th Combustion Subcommittee (CS), 26 th Airbreathing Propulsion Subcommittee (APS), 20th Propulsion Systems Hazards Subcommittee (PSHS), and 21 Modeling and Simulation Subcommittee. The meeting was held 8-12 April 2002 at the Bayside Inn at The Sandestin Golf & Beach Resort and Eglin Air Force Base, Destin, Florida. Topics cover five major technology areas including: 1) Combustion - Propellant Combustion, Ingredient Kinetics, Metal Combustion, Decomposition Processes and Material Characterization, Rocket Motor Combustion, and Liquid & Hybrid Combustion; 2) Liquid Rocket Engines - Low Cost Hydrocarbon Liquid Rocket Engines, Liquid Propulsion Turbines, Liquid Propulsion Pumps, and Staged Combustion Injector Technology; 3) Modeling & Simulation - Development of Multi- Disciplinary RBCC Modeling, Gun Modeling, and Computational Modeling for Liquid Propellant Combustion; 4) Guns Gun Propelling Charge Design, and ETC Gun Propulsion; and 5) Airbreathing - Scramjet an Ramjet- S&T Program Overviews.

  2. Appraisal of biomass combustion biomarkers to track the paleo-occurrence of forest fires

    NASA Astrophysics Data System (ADS)

    Rivas-Ruiz, P.; Cao, M.; Rosell Mele, A.

    2015-12-01

    Wildfires influence many aspects of the Earth system, including ecosystem distribution, biodiversity, the carbon cycle, atmospheric chemistry and climate. The challenge is disentangling the various controls of fire, partly because of their diversity, and also because fire was impossible to observe and analyse as a global phenomenon until the satellite era. The study of ancient climates can be helpful to understand the natural drivers of wildfires. However, the reconstruction of wildfires is limited by the nature of the proxies available, chiefly charcoal, which only represents a portion of the carbon combustion continuum. In here we evaluate the application molecular combustion biomarkers. For this purpose we have compiled an extensive collection of soils and lacustrine sediments representative of the humid to arid environments, which encompass the wide range of climates and ecosystems within the Iberian peninsula. We have measured the abundance of a monosaccharide anhydride (MA) biomarker called levoglucosan (1,6-anhydro-β-D-glucopyranose) and polyaromatic hydrocarbons (PAHs), as well as general plant biomarkers such as n-alkanes. To discern between biogenic and/or anthropogenic combustion sources and the nature of fires we have investigated the use of levoglucosan, retene (PAH generated during combustion of conifer trees) and PAHs ratios such as phenantrane/anthracene and fluoranthene/pyrene. Charcoal (>150 microns) has also been measured in the lake samples to contribute in the assessment of local vs. regions fire signals. The final objective is to constrain the use of the molecular proxies as quantitative biomass combustion paleoproxies. The data obtained has been mapped and compared to the documented occurrence of wildfires in Spain over the last two decades, and mesoescale patterns of atmospheric circulation and particle transport. Results show that the occurrence of levoglucosan and PAHs is widespread in modern soils and sediments in Iberia. Chemical

  3. Combustion and core noise

    NASA Astrophysics Data System (ADS)

    Mahan, J. Robert; Karchmer, Allen

    1991-08-01

    Two types of aircraft power plant are considered: the gas turbine and the reciprocating engine. The engine types considered are: the reciprocating engine, the turbojet engine, the turboprop engine, and the turbofan engine. Combustion noise in gas turbine engines is discussed, and reciprocating-engine combustion noise is also briefly described. The following subject areas are covered: configuration variables, operational variables, characteristics of combustion and core noise, sources of combustion noise, combustion noise theory and comparison with experiment, available prediction methods, diagnostic techniques, measurement techniques, data interpretation, and example applications.

  4. Plasma Processing Of Hydrocarbon

    SciTech Connect

    Grandy, Jon D; Peter C. Kong; Brent A. Detering; Larry D. Zuck

    2007-05-01

    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.

  5. Hydrocarbon treating process

    SciTech Connect

    Verachtert, T. A.

    1984-11-06

    A process is disclosed for treating hydrocarbon streams such as naphtha by the oxidation of mercaptans into disulfide compounds which remain in the hydrocarbon stream. The conversion is effected during passage of the hydrocarbon and an aqueous stream downward through a cylindrical mass of liquid-liquid contact material. The liquids then flow through a cylindrical screen into an annular separation zone which surrounds a lower part of the contact material. After decantation in the separation zone, the aqueous material, which preferably contains the oxidation catalyst, is recycled.

  6. Natural hydrocarbons, urbanization, and urban ozone

    SciTech Connect

    Cardelino, C.A.; Chameides, W.L. )

    1990-08-20

    Using the Atlanta metropolitan area as a case study, the authors examine the effects of urbanization and its associated heat island on urban ozone concentrations. Air quality data from Atlanta suggest that urban ozone concentrations are enhanced by increases in ambient temperature. Model calculations suggest that this enhancement is caused by the effect of temperature on the atmospheric chemistry of peroxyacetyl nitrate (PAN), as well as the temperature dependence of natural and anthropogenic hydrocarbon emissions. A comparison of summertime temperatures in Atlanta and a nearby rural station, suggests that Atlanta's temperature over the past 15 years has increased by about 2{degree}C due to urbanization and its concomitant intensification of the urban heat island. Numerical simulations using conditions of a typical summertime day in Atlanta suggest that this rise in temperature could have, (1) resulted in a significant increase in the net emissions of natural hydrocarbons in the area in spite of the loss of about 20% of the areas forests over the same period, and (2) negated the beneficial effects on summertime ozone concentrations that would have been obtained from a 50% reduction in anthropogenic hydrocarbon emissions. Because a NO{sub x}-based ozone abatement strategy appears to be less sensitive to temperature increases than does a hydrocarbon-based strategy, a NO{sub x} strategy may prove to be more effective in the future if temperatures continue to rise as a result of urbanization and the greenhouse effect.

  7. Improving Dryer and Press Efficiencies Through Combustion of Hydrocarbon Emissions

    SciTech Connect

    Sujit Banerjee

    2005-10-31

    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.

  8. Carbon deposition model for oxygen-hydrocarbon combustion

    NASA Technical Reports Server (NTRS)

    Bossard, John A.

    1988-01-01

    The objectives are to use existing hardware to verify and extend the database generated on the original test programs. The data to be obtained are the carbon deposition characteristics when methane is used at injection densities comparable to full scale values. The database will be extended to include liquid natural gas (LNG) testing at low injection densities for gas generator/preburner conditions. The testing will be performed at mixture ratios between 0.25 and 0.60, and at chamber pressures between 750 and 1500 psi.

  9. Chemistry Notes.

    ERIC Educational Resources Information Center

    School Science Review, 1980

    1980-01-01

    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)

  10. Chemistry Notes

    ERIC Educational Resources Information Center

    School Science Review, 1973

    1973-01-01

    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)

  11. Nuclear Chemistry.

    ERIC Educational Resources Information Center

    Chemical and Engineering News, 1979

    1979-01-01

    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)

  12. Catalytic Chemistry.

    ERIC Educational Resources Information Center

    Borer, Londa; And Others

    1996-01-01

    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)

  13. Chemistry Notes.

    ERIC Educational Resources Information Center

    School Science Review, 1981

    1981-01-01

    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)

  14. Precolumbian Chemistry.

    ERIC Educational Resources Information Center

    Robinson, Janet Bond

    1995-01-01

    Describes the content and development of a curriculum that provides an approach to descriptive chemistry and the history of technology through consideration of the pottery, metallurgy, pigments, dyes, agriculture, and medicine of pre-Columbian people. (DDR)

  15. Stratospheric chemistry

    SciTech Connect

    Brune, W.H. )

    1991-01-01

    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.

  16. Opportunities in pulse combustion

    NASA Astrophysics Data System (ADS)

    Brenchley, D. L.; Bomelburg, H. J.

    1985-10-01

    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.

  17. Natural hydrocarbons, urbanization, and urban ozone

    NASA Technical Reports Server (NTRS)

    Cardelino, C. A.; Chameides, W. L.

    1990-01-01

    The combined effects of emission control and urbanization, with its concomitant intensification of the urban heat island, on urban ozone concentrations are studied. The effect of temperature on ozone is considered, and attention is given to the temperature effect on ozone photochemistry. Model calculations suggest that ozone concentration enhancements are caused by the effect of temperature on the atmospheric chemistry of peroxyacetyl nitrate, as well as the temperature dependence of natural and anthropogenic hydrocarbon emissions. It is pointed out that, because of the sensitivity of urban ozone to local climatic conditions and the ability of trees to moderate summertime temperatures, the inadvertent removal of trees from urbanization can have an adverse effect on urban ozone concentration, while a temperature increase in the urban heat island caused by urbanization can essentially cancel out the ozone-reducing benefits obtained from a 50-percent reduction in anthropogenic hydrocarbon emissions.

  18. Organic chemistry on Titan

    NASA Technical Reports Server (NTRS)

    Chang, S.; Scattergood, T.; Aronowitz, S.; Flores, J.

    1978-01-01

    Observations of nonequilibrium phenomena on the Saturn satellite Titan indicate the occurrence of organic chemical evolution. Greenhouse and thermal inversion models of Titan's atmosphere provide environmental constraints within which various pathways for organic chemical synthesis are assessed. Experimental results and theoretical modeling studies suggest that the organic chemistry of the satellite may be dominated by two atmospheric processes: energetic-particle bombardment and photochemistry. Reactions initiated in various levels of the atmosphere by cosmic ray, Saturn wind, and solar wind particle bombardment of a CH4 - N2 atmospheric mixture can account for the C2-hydrocarbons, the UV-visible-absorbing stratospheric haze, and the reddish color of the satellite. Photochemical reactions of CH4 can also account for the presence of C2-hydrocarbons. In the lower Titan atmosphere, photochemical processes will be important if surface temperatures are sufficiently high for gaseous NH3 to exist. Hot H-atom reactions initiated by photo-dissociation of NH3 can couple the chemical reactions of NH3 and CH4 and produce organic matter.

  19. Surrogate Model Development for Fuels for Advanced Combustion Engines

    SciTech Connect

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

    2011-01-01

    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.

  20. Experimentally Determined Binding Energies of Astrophysically Relevant Hydrocarbons

    NASA Astrophysics Data System (ADS)

    Behmard, Aida; Graninger, Dawn; Oberg, Karin I.

    2016-06-01

    Small hydrocarbons represent an important organic reservoir in a variety of interstellar environments. Constraints on desorption temperatures and binding energies of hydrocarbons are thus necessary for accurate predictions of where and in which phase these molecules exist. Through a series of temperature programmed desorption experiments, we determined the desorption temperatures and binding energies of 1, 2, and 3-carbon interstellar hydrocarbons (CH4, H3CCH3, H2CCH2, C3H8, HCCCH3, and C3H6). These empirically determined values can be used to inform observations and models of the molecular spatial distribution in protoplanetary disks, thus providing insight into planetesimal composition. In addition, knowledge of hydrocarbon binding energies will refine simulations of grain surface chemistry, allowing for better predictions of the chemical conditions that lead to the production of complex organic molecules vital for life.

  1. Hydrocarbon recovery from diatomite

    SciTech Connect

    Scinta, J.

    1984-05-15

    Supercritical extraction of diatomaceous earth results in a much more significant improvement in hydrocarbon recovery over Fischer retorting than achievable with tar sands. Process and apparatus for supercritical extraction of diatomaceous earth are disclosed.

  2. Combustion and flow modelling applied to the OMV VTE

    NASA Technical Reports Server (NTRS)

    Larosiliere, Louis M.; Jeng, San-Mou

    1990-01-01

    A predictive tool for hypergolic bipropellant spray combustion and flow evolution in the OMV VTE (orbital maneuvering vehicle variable thrust engine) is described. It encompasses a computational technique for the gas phase governing equations, a discrete particle method for liquid bipropellant sprays, and constitutive models for combustion chemistry, interphase exchanges, and unlike impinging liquid hypergolic stream interactions. Emphasis is placed on the phenomenological modelling of the hypergolic liquid bipropellant gasification processes. An application to the OMV VTE combustion chamber is given in order to show some of the capabilities and inadequacies of this tool.

  3. Hypergolic bipropellant spray combustion and flow modelling in rocket engines

    NASA Technical Reports Server (NTRS)

    Larosiliere, Louis M.; Litchford, Ron J.; Jeng, San-Mou

    1990-01-01

    A predictive tool for hypergolic bipropellant spray combustion and flow evolution in small rocket combustion chambers is described. It encompasses a computational technique for the gas-phase governing equations, a discrete particle method for liquid bipropellant sprays, and constitutive models for combustion chemistry, interphase exchanges, and unlike impinging hypergolic spray interactions. Emphasis is placed on the phenomenological modeling of the hypergolic liquid bipropellant gasification processes. Sample computations with the N2H4-N2O4 propellant system are given in order to show some of the capabilities and inadequacies of this tool.

  4. Supercritical droplet combustion and related transport phenomena

    NASA Technical Reports Server (NTRS)

    Yang, Vigor; Hsieh, K. C.; Shuen, J. S.

    1993-01-01

    An overview of recent advances in theoretical analyses of supercritical droplet vaporization and combustion is conducted. Both hydrocarbon and cryogenic liquid droplets over a wide range of thermodynamic states are considered. Various important high-pressure effects on droplet behavior, such as thermodynamic non-ideality, transport anomaly, and property variation, are reviewed. Results indicate that the ambient gas pressure exerts significant control of droplet gasification and burning processes through its influence on fluid transport, gas-liquid interfacial thermodynamics, and chemical reactions. The droplet gasification rate increases progressively with pressure. However, the data for the overall burnout time exhibit a considerable change in the combustion mechanism at the criticl pressure, mainly as a result of reduced mass diffusivity and latent heat of vaporization with increased pressure. The influence of droplet size on the burning characteristics is also noted.

  5. Chemistry of Aviation Fuels

    NASA Technical Reports Server (NTRS)

    Knepper, Bryan; Hwang, Soon Muk; DeWitt, Kenneth J.

    2004-01-01

    Minimum ignition energies of various methanol/air mixtures were measured in a temperature controlled constant volume combustion vessel using a spark ignition method with a spark gap distance of 2 mm. The minimum ignition energies decrease rapidly as the mixture composition (equivalence ratio, Phi) changes from lean to stoichiometric, reach a minimum value, and then increase rather slowly with Phi. The minimum of the minimum ignition energy (MIE) and the corresponding mixture composition were determined to be 0.137 mJ and Phi = 1.16, a slightly rich mixture. The variation of minimum ignition energy with respect to the mixture composition is explained in terms of changes in reaction chemistry.

  6. Membrane separation of hydrocarbons

    DOEpatents

    Funk, Edward W.; Kulkarni, Sudhir S.; Chang, Y. Alice

    1986-01-01

    Mixtures of heavy oils and light hydrocarbons may be separated by passing the mixture over a polymeric membrane which comprises a polymer capable of maintaining its integrity in the presence of hydrocarbon compounds at temperature ranging from about ambient to about 100.degree. C. and pressures ranging from about 50 to about 1000 psi. The membranes which possess pore sizes ranging from about 10 to about 500 Angstroms are cast from a solvent solution and recovered.

  7. Hydrocarbon geoscience research strategy

    SciTech Connect

    Not Available

    1990-04-01

    This document outlines a strategy for oil and gas related research focused on optimizing the economic producibility of the Nation's resources. The Hydrocarbon Geoscience Strategy was developed by the Hydrocarbon Geoscience Research Coordinating Committee of the Department of Energy (DOE). This strategy forms the basis for the development of DOE Fossil Energy's Oil Research Program Implementation Plan and Natural Gas Program Implementation Plan. 24 refs., 5 figs., 3 tabs.

  8. Sampling nitric oxide from combustion gases.

    NASA Technical Reports Server (NTRS)

    England, C.; Houseman, J.; Teixeira, D. P.

    1973-01-01

    Experimental study of several sampling tube and probe material compositions and designs aimed at preventing nitric oxide reduction when sampling nitric oxide from combustion gases. A 250,000 Btu/h furnace fired with technical grade methane was used for testing the sampling probes over a wide range of air-fuel mixtures. The results obtained include the finding that the use of stainless steel in probes creates inaccuracies in near-stoichiometric and fuel-rich sampling in hydrocarbon flames. For very fuel-rich flames, water cooling is needed even in quartz probes to prevent significant reduction of nitric oxide.-

  9. Studies of combustion kinetics and mechanisms

    SciTech Connect

    Gutman, D.

    1993-12-01

    The objective of the current research is to gain new quantitative knowledge of the kinetics and mechanisms of polyatomic free radicals which are important in hydrocarbon combustion processes. The special facility designed and built for these (which includes a heatable tubular reactor coupled to a photoionization mass spectrometer) is continually being improved. Where possible, these experimental studies are coupled with theoretical ones, sometimes conducted in collaboration with others, to obtain an improved understanding of the factors determining reactivity. The decomposition of acetyl radicals, isopropyl radicals, and n-propyl radicals have been studied as well as the oxidation of methylpropargyl radicals.

  10. Combustion characteristics of gas turbine alternative fuels

    NASA Technical Reports Server (NTRS)

    Rollbuhler, R. James

    1987-01-01

    An experimental investigation was conducted to obtain combustion performance values for specific heavyend, synthetic hydrocarbon fuels. A flame tube combustor modified to duplicate an advanced gas turbine engine combustor was used for the tests. Each fuel was tested at steady-state operating conditions over a range of mass flow rates, fuel-to-air mass ratio, and inlet air temperatures. The combustion pressure, as well as the hardware, were kept nearly constant over the program test phase. Test results were obtained in regards to geometric temperature pattern factors as a function of combustor wall temperatures, the combustion gas temperature, and the combustion emissions, both as affected by the mass flow rate and fuel-to-air ratio. The synthetic fuels were reacted in the combustor such that for most tests their performance was as good, if not better, than the baseline gasoline or diesel fuel tests. The only detrimental effects were that at high inlet air temperature conditions, fuel decomposition occurred in the fuel atomizing nozzle passages resulting in blockage. And the nitrogen oxide emissions were above EPA limits at low flow rate and high operating temperature conditions.

  11. The effect of insulated combustion chamber surfaces on direct-injected diesel engine performance, emissions, and combustion

    NASA Technical Reports Server (NTRS)

    Dickey, Daniel W.; Vinyard, Shannon; Keribar, Rifat

    1988-01-01

    The combustion chamber of a single-cylinder, direct-injected diesel engine was insulated with ceramic coatings to determine the effect of low heat rejection (LHR) operation on engine performance, emissions, and combustion. In comparison to the baseline cooled engine, the LHR engine had lower thermal efficiency, with higher smoke, particulate, and full load carbon monoxide emissions. The unburned hydrocarbon emissions were reduced across the load range. The nitrous oxide emissions increased at some part-load conditions and were reduced slightly at full loads. The poor LHR engine performance was attributed to degraded combustion characterized by less premixed burning, lower heat release rates, and longer combustion duration compared to the baseline cooled engine.

  12. Boiler using combustible fluid

    DOEpatents

    Baumgartner, H.; Meier, J.G.

    1974-07-03

    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.

  13. HYDROCARBON FORMATION ON POLYMER-SUPPORTED COBALT

    SciTech Connect

    Benner, Linda S.; Perkins, Patrick; Vollhardt, K.Peter C.

    1980-10-01

    In this report we detail the synthesis catalytic chemistry of polystyrene supported {eta}{sup 5} ~cyclopentadienyl- dicarbonyl cobalt, CpCo(CO){sub 2}. This material is active in the hydrogenation of CO to saturated linear hydrocarbons and appears to retain its "homogeneous", mononuclear character during the course of its catalysis, During ·the course of our work 18% and 20% crosslinked analogs of polystyrene supported CpCo(CO){sub 2} were shown to exhibit limited catalytic activity and no CO activation.

  14. Molecular Aluminum Additive for Burn Enhancement of Hydrocarbon Fuels.

    PubMed

    Guerieri, Philip M; DeCarlo, Samantha; Eichhorn, Bryan; Connell, Terrence; Yetter, Richard A; Tang, Xin; Hicks, Zachary; Bowen, Kit H; Zachariah, Michael R

    2015-11-12

    Additives to hydrocarbon fuels are commonly explored to change the combustion dynamics, chemical distribution, and/or product integrity. Here we employ a novel aluminum-based molecular additive, Al(I) tetrameric cluster [AlBrNEt3]4 (Et = C2H5), to a hydrocarbon fuel and evaluate the resultant single-droplet combustion properties. This Al4 cluster offers a soluble alternative to nanoscale particulate additives that have recently been explored and may mitigate the observed problems of particle aggregation. Results show the [AlBrNEt3]4 additive to increase the burn rate constant of a toluene-diethyl ether fuel mixture by ∼20% in a room temperature oxygen environment with only 39 mM of active aluminum additive (0.16 wt % limited by additive solubility). In comparison, a roughly similar addition of nano-aluminum particulate shows no discernible difference in burn properties of the hydrocarbon fuel. High speed video shows the [AlBrNEt3]4 to induce microexplosive gas release events during the last ∼30% of the droplet combustion time. We attribute this to HBr gas release based on results of temperature-programmed reaction (TPR) experiments of the [AlBrNEt3]4 dosed with O2 and D2O. A possible mechanism of burn rate enhancement is presented that is consistent with microexplosion observations and TPR results. PMID:26488461

  15. A combustion model for IC engine combustion simulations with multi-component fuels

    SciTech Connect

    Ra, Youngchul; Reitz, Rolf D.

    2011-01-15

    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)

  16. Interstellar Grain Surface Chemistry

    NASA Technical Reports Server (NTRS)

    Tielens, Alexander G. G. M.; Cuzzi, Jeffrey N. (Technical Monitor)

    1995-01-01

    Chemistry on grain surfaces plays an Important role in the formation of interstellar Ices, It can also influence the composition of the gas phase through outgassing near luminous, newly formed stars. This paper reviews the chemical processes taking place on Interstellar grain surfaces with the emphasis on those transforming CO into other hydrocarbons. At low, molecular cloud temperatures (approximately equal to 10K), physisorption processes dominate interstellar grain surface chemistry and GO is largely hydrogenated through reactions with atomic H and oxidized through reactions with atomic O. The former will lead to the formation of H2CO and CH3OH ices, while the latter results in CO2 ice. The observational evidence for these ices in molecular clouds will be discussed. Very close to protostars, the gas and grain temperatures are much higher (approximately equal to 500K) and chemisorption processes, including catalytic surface reactions, becomes important. This will be illustrated based upon our studies of the Fischer-Tropsch Synthesis of CH4 from CO on metallic surfaces. Likely, this process has played an important role in the early solar nebula. Observational consequences will be pointed out.

  17. Combustion of Micropowdered Biomass

    NASA Astrophysics Data System (ADS)

    Geil, Ethan; Thorne, Robert

    2009-03-01

    Combustion of finely powdered biomass has the potential to replace heating oil, which accounts for a significant fraction of US oil consumption, in heating, cooling and local power generation applications. When ground to 30-150 micron powders and dispersed in air, wood and other biomass can undergo deflagrating combustion, as occurs with gaseous and dispersed liquid fuels. Combustion is very nearly complete, and in contrast to sugar/starch or cellulose-derived ethanol, nearly all of the available plant mass is converted to usable energy so the economics are much more promising. We are exploring the fundamental combustion science of biomass powders in this size range. In particular, we are examining how powder size, powder composition (including the fraction of volatile organics) and other parameters affect the combustion regime and the combustion products.

  18. Lump wood combustion process

    NASA Astrophysics Data System (ADS)

    Kubesa, Petr; Horák, Jiří; Branc, Michal; Krpec, Kamil; Hopan, František; Koloničný, Jan; Ochodek, Tadeáš; Drastichová, Vendula; Martiník, Lubomír; Malcho, Milan

    2014-08-01

    The article deals with the combustion process for lump wood in low-power fireplaces (units to dozens of kW). Such a combustion process is cyclical in its nature, and what combustion facility users are most interested in is the frequency, at which fuel needs to be stoked to the fireplace. The paper defines the basic terms such as burnout curve and burning rate curve, which are closely related to the stocking frequency. The fuel burning rate is directly dependent on the immediate thermal power of the fireplace. This is also related to the temperature achieved in the fireplace, magnitude of flue gas losses and the ability to generate conditions favouring the full burnout of the fuel's combustible component, which, at once ensures the minimum production of combustible pollutants. Another part of the paper describes experiments conducted in traditional fireplaces with a grate, at which well-dried lump wood was combusted.

  19. Aliphatics hydrocarbon content in surface sediment from Jakarta Bay, Indonesia

    NASA Astrophysics Data System (ADS)

    YAzis, M.; Asia, L.; Piram, A.; Doumenq, P.; Syakti, A. D.

    2016-02-01

    Sedimentary aliphatic hydrocarbons content have been studied quantitatively and qualitatively using GC/MS method in eight coastal stations located in the Jakarta Bay, North of Jakarta, Indonesia. The total concentrations n-alkanes have ranged from 480 μg.kg-1to 1,935 μg.kg-1sediment dry weight. Several ratios (e.g. CPI24-32, NAR, TAR, Pr/Phy, n-C17/Pr, n- C18/Phyt,n-C29/n-C17, Ʃn-alkanes/n-C16LMW/HMW, Paq and TMD) were used to evaluate the possible sources of terrestrial-marine inputs of these hydrocarbons in the sediments. The various origins of aliphatic hydrocarbons were generally biogenic, including both terrigenous and marine, with an anthropogenic pyrolytic contribution (petrogenic and biogenic combustion). Two stations (G,H) were thehighest concentration and had potential risk to environment

  20. Measurement of polynuclear aromatic hydrocarbon concentrations in the plume of Kuwait oil well fires

    SciTech Connect

    Olsen, K.B.; Wright, C.W.; Veverka, C.; Ball, J.C.; Stevens, R.

    1995-03-01

    Following their retreat from Kuwait during February and March of 1991, the Iraqi Army set fire to over 500 oil wells dispersed throughout the Kuwait oil fields. During the period of sampling from July to August 1991, it was estimated that between 3.29 {times} 10{sup 6} barrels per day of crude oil were combusted. The resulting fires produced several plumes of black and white smoke that coalesced to form a composite ``super`` plume. Because these fires were uncontrolled, significant quantities of organic materials were dispersed into the atmosphere and drifted throughout the Middle East. The organic particulants associated with the plume of the oil well fires had a potential to be rich in polynuclear aromatic hydrocarbon (PAH) compounds. Based on the extreme mutagenic and carcinogenic activities of PAHs found in laboratory testing, a serious health threat to the population of that region potentially existed. Furthermore, the Kuwait oil fire plumes represented a unique opportunity to study the atmospheric chemistry associated with PAHs in the plume. If samples were collected near the plume source and from the plume many kilometers downwind from the source, comparisons could be made to better understand atmospheric reactions associated with particle-bound and gas-phase PAHs. To help answer health-related concerns and to better understand the fate and transport of PAHs in an atmospheric environment, a sampling and analysis program was developed.

  1. Coal combustion products

    USGS Publications Warehouse

    Kalyoncu, R.S.; Olson, D.W.

    2001-01-01

    Coal-burning powerplants, which supply more than half of U.S. electricity, also generate coal combustion products, which can be both a resource and a disposal problem. The U.S. Geological Survey collaborates with the American Coal Ash Association in preparing its annual report on coal combustion products. This Fact Sheet answers questions about present and potential uses of coal combustion products.

  2. The dynamics of flash fires involving flammable hydrocarbon liquids.

    PubMed

    DeHaan, J D

    1996-03-01

    Victims of fires are sometimes discovered to have less-than-lethal levels of carbon monoxide (CO) in the blood and no significant antemortem fire damage. Such occurrences are often linked to flash fires involving volatile hydrocarbon fuels. In this study, the dynamics of hydrocarbon fuel fires are examined, and the results of fullscale room tests ignited with small (< 2 L) quantities of flammable liquid are found to confirm the theoretical predictions. These tests showed that flame plumes with temperatures of 500-975 degrees C were produced above flammable liquids. Ignition of their vapors in a carpeted room produced a very short-lived flash of fire throughout the room, followed by intense flames in a layer above the floor approximately 1 m deep, which quickly degenerated to isolated pools of low flames. Combustion of hydrocarbon vapors in a room caused oxygen levels to drop below 8.5% in < 100 s, while causing carbon dioxide (CO2) levels to increase to 12-16% whether the door to the room was open or closed. Production of CO trailed maximum CO2 production by 15-30 s. A victim exposed to such a fire may collapse from extreme heat (aided by the water vapor created by the combustion of hydrocarbons), weakened by oxygen deprivation, before CO inhalation becomes a significant factor. PMID:8838466

  3. The role of isovalency in the reactions of the cyano (CN), boron monoxide (BO), silicon nitride (SiN), and ethynyl (C2H) radicals with unsaturated hydrocarbons acetylene (C2H2) and ethylene (C2H4).

    PubMed

    Parker, D S N; Mebel, A M; Kaiser, R I

    2014-04-21

    The classification of chemical reactions based on shared characteristics is at the heart of the chemical sciences, and is well exemplified by Langmuir's concept of isovalency, in which 'two molecular entities with the same number of valence electrons have similar chemistries'. Within this account we further investigate the ramifications of the isovalency of four radicals with the same X(2)Σ(+) electronic structure - cyano (CN), boron monoxide (BO), silicon nitride (SiN), and ethynyl (C2H), and their reactions with simple prototype hydrocarbons acetylene (C2H2) and ethylene (C2H4). The fact that these four reactants own the same X(2)Σ(+) electronic ground state should dictate the outcome of their reactions with prototypical hydrocarbons holding a carbon-carbon triple and double bond. However, we find that other factors come into play, namely, atomic radii, bonding orbital overlaps, and preferential location of the radical site. These doublet radical reactions with simple hydrocarbons play significant roles in extreme environments such as the interstellar medium and planetary atmospheres (CN, SiN and C2H), and combustion flames (C2H, BO). PMID:24418936

  4. Characterization of a nose-only inhalation exposure system for hydrocarbon mixtures and jet fuels.

    PubMed

    Martin, Sheppard A; Tremblay, Raphael T; Brunson, Kristyn F; Kendrick, Christine; Fisher, Jeffrey W

    2010-04-01

    A directed-flow nose-only inhalation exposure system was constructed to support development of physiologically based pharmacokinetic (PBPK) models for complex hydrocarbon mixtures, such as jet fuels. Due to the complex nature of the aerosol and vapor-phase hydrocarbon exposures, care was taken to investigate the chamber hydrocarbon stability, vapor and aerosol droplet compositions, and droplet size distribution. Two-generation systems for aerosolizing fuel and hydrocarbons were compared and characterized for use with either jet fuels or a simple mixture of eight hydrocarbons. Total hydrocarbon concentration was monitored via online gas chromatography (GC). Aerosol/vapor (A/V) ratios, and total and individual hydrocarbon concentrations, were determined using adsorbent tubes analyzed by thermal desorption-gas chromatography-mass spectrometry (TDS-GC-MS). Droplet size distribution was assessed via seven-stage cascade impactor. Droplet mass median aerodynamic diameter (MMAD) was between 1 and 3 mum, depending on the generator and mixture utilized. A/V hydrocarbon concentrations ranged from approximately 200 to 1300 mg/m(3), with between 20% and 80% aerosol content, depending on the mixture. The aerosolized hydrocarbon mixtures remained stable during the 4-h exposure periods, with coefficients of variation (CV) of less than 10% for the total hydrocarbon concentrations. There was greater variability in the measurement of individual hydrocarbons in the A-V phase. In conclusion, modern analytical chemistry instruments allow for improved descriptions of inhalation exposures of rodents to aerosolized fuel. PMID:20109056

  5. Chemistry Experiments

    NASA Technical Reports Server (NTRS)

    Brasseur, Guy; Remsberg, Ellis; Purcell, Patrick; Bhatt, Praful; Sage, Karen H.; Brown, Donald E.; Scott, Courtney J.; Ko, Malcolm K. W.; Tie, Xue-Xi; Huang, Theresa

    1999-01-01

    The purpose of the chemistry component of the model comparison is to assess to what extent differences in the formulation of chemical processes explain the variance between model results. Observed concentrations of chemical compounds are used to estimate to what degree the various models represent realistic situations. For readability, the materials for the chemistry experiment are reported in three separate sections. This section discussed the data used to evaluate the models in their simulation of the source gases and the Nitrogen compounds (NO(y)) and Chlorine compounds (Cl(y)) species.

  6. Tropospheric chemistry

    NASA Technical Reports Server (NTRS)

    Mohnen, V. A.; Chameides, W.; Demerjian, K. L.; Lenschow, D. H.; Logan, J. A.; Mcneal, R. J.; Penkett, S. A.; Platt, U.; Schurath, U.; Dias, P. D.

    1985-01-01

    The chemistry of the background troposphere, the source region, and the transition regions are discussed. The troposphere is governed by heterogeneous chemistry far more so than the stratosphere. Heterogeneous processes of interest involve scavenging of trace gases by aerosols, cloud and precipitation elements leading to aqueous phase chemical reactions and to temporary and permanent removal of material from the gas phase. Dry deposition is a major removal process for ozone, as well as for other gases of importance in tropospheric photochemistry. These processes are also discussed.

  7. Polymer Chemistry

    NASA Technical Reports Server (NTRS)

    Williams, Martha; Roberson, Luke; Caraccio, Anne

    2010-01-01

    This viewgraph presentation describes new technologies in polymer and material chemistry that benefits NASA programs and missions. The topics include: 1) What are Polymers?; 2) History of Polymer Chemistry; 3) Composites/Materials Development at KSC; 4) Why Wiring; 5) Next Generation Wiring Materials; 6) Wire System Materials and Integration; 7) Self-Healing Wire Repair; 8) Smart Wiring Summary; 9) Fire and Polymers; 10) Aerogel Technology; 11) Aerogel Composites; 12) Aerogels for Oil Remediation; 13) KSC's Solution; 14) Chemochromic Hydrogen Sensors; 15) STS-130 and 131 Operations; 16) HyperPigment; 17) Antimicrobial Materials; 18) Conductive Inks Formulations for Multiple Applications; and 19) Testing and Processing Equipment.

  8. Combustion Byproducts Recycling Consortium

    SciTech Connect

    Paul Ziemkiewicz; Tamara Vandivort; Debra Pflughoeft-Hassett; Y. Paul Chugh; James Hower

    2008-08-31

    Ashlines: To promote and support the commercially viable and environmentally sound recycling of coal combustion byproducts for productive uses through scientific research, development, and field testing.

  9. Diesel engine combustion processes

    SciTech Connect

    1995-12-31

    Diesel Engine Combustion Processes guides the engineer and research technician toward engine designs which will give the ``best payoff`` in terms of emissions and fuel economy. Contents include: Three-dimensional modeling of soot and NO in a direct-injection diesel engine; Prechamber for lean burn for low NOx; Modeling and identification of a diesel combustion process with the downhill gradient search method; The droplet group micro-explosions in W/O diesel fuel emulsion sprays; Combustion process of diesel spray in high temperature air; Combustion process of diesel engines at regions with different altitude; and more.

  10. STRUCTURE-BASED PREDICTIVE MODEL FOR COAL CHAR COMBUSTION

    SciTech Connect

    CHRISTOPHER M. HADAD; JOSEPH M. CALO; ROBERT H. ESSENHIGH; ROBERT H. HURT

    1998-06-04

    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

  11. Accumulation of polycyclic aromatic hydrocarbons in acid sensitive lakes

    SciTech Connect

    Furlong, E.T.; Cessar, L.R.; Hites, R.A. )

    1987-11-01

    Polycyclic aromatic hydrocarbon concentrations and fluxes were measured in {sup 210}Pb dated sediment cores taken from nine lakes in four regions identified as susceptible to acidification. Calculated PAH accumulations were compared with historic S emissions, accumulation of sedimentary S, and anthropogenic metal accumulations to determine if PAH could be used as an indicator of combustion-derived sulfate deposition. Comparisons between regions indicated that the Adirondacks have a significantly higher burden of PAH than do northern New England, the northern Great Lakes States, and northern Florida. This difference likely results from significant upwind PAH sources to the Adirondack lakes. Detailed investigation of the largest lake in the study set, Big Moose Lake, indicates that PAH may serve as conservative, combustion indicators in large lakes. In this lake, PAH fluxes and concentrations were significantly correlated with historical S emission rates. These data suggest that PAH measured in sediment cores from large lakes can serve as indicators of past combustion production deposition.

  12. Accumulation of polycyclic aromatic hydrocarbons in acid sensitive lakes

    NASA Astrophysics Data System (ADS)

    Furlong, Edward T.; Cessar, Linda Roll; Hites, Ronald A.

    1987-11-01

    Polycyclic aromatic hydrocarbon concentrations and fluxes were measured in 210Pb dated sediment cores taken from nine lakes in four regions identified as susceptible to acidification. Calculated PAH accumulations were compared with historic S emissions, accumulation of sedimentary S and anthropogenic metal accumulations to determine if PAH could be used as an indicator of combustion-derived sulfate deposition. Comparisons between regions indicated that the Adirondacks have a significantly higher burden of PAH than do northern New England, the northern Great Lakes States and northern Florida. This difference likely results from significant upwind PAH sources to the Adirondack lakes. Detailed investigation of the largest lake in the study set, Big Moose Lake, indicates that PAH may serve as conservative, combustion indicators in large lakes. In this lake, PAH fluxes and concentrations were significantly correlated with historical S emission rates. These data suggest that PAH measured in sediment cores from large lakes can serve as indicators of past combustion product deposition.

  13. Symposium on Combustion /International/, 16th, Massachusetts Institute of Technology, Cambridge, Mass., August 15-20, 1976, Proceedings

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Aspects of combustion technology in power systems are considered, taking into account a combustion in large boilers, the control of over-all thermal efficiency of combustion heating systems, a comparison of mathematical models of the radiative behavior of a large-scale experimental furnace, a concentric multiannular swirl burner, and the effects of water introduction on diesel engine combustion and emissions. Attention is also given to combustion and related processes in energy production from coal, spray and droplet combustion, soot formation and growth, the kinetics of elementary reactions, flame structure and chemistry, propellant ignition and combustion, fire and explosion research, mathematical modeling, high output combustion systems, turbulent flames and combustion, and ignition, optical, and electrical properties.

  14. Method for producing hydrocarbon fuels and fuel gas from heavy polynuclear hydrocarbons by the use of molten metal halide catalysts

    DOEpatents

    Gorin, Everett

    1979-01-01

    In a process for hydrocracking heavy polynuclear carbonaceous feedstocks to produce lighter hydrocarbon fuels by contacting the heavy feedstocks with hydrogen in the presence of a molten metal halide catalyst in a hydrocracking zone, thereafter separating at least a major portion of the lighter hydrocarbon fuels from the spent molten metal halide and thereafter regenerating the spent molten metal halide by incinerating the spent molten metal halide by combustion of carbon and sulfur compounds in the spent molten metal halide in an incineration zone, the improvement comprising: (a) contacting the heavy feedstocks and hydrogen in the presence of the molten metal halide in the hydrocracking zone at reaction conditions effective to convert from about 60 to about 90 weight percent of the feedstock to lighter hydrocarbon fuels; (b) separating at least a major portion of the lighter hydrocarbon fuels from the spent molten metal halide; (c) contacting the spent molten metal halide with oxygen in a liquid phase gasification zone at a temperature and pressure sufficient to vaporize from about 25 to about 75 weight percent of the spent metal halide, the oxygen being introduced in an amount sufficient to remove from about 60 to about 90 weight percent of the carbon contained in the spent molten metal halide to produce a fuel gas and regenerated metal halide; and (d) incinerating the spent molten metal halide by combusting carbon and sulfur compounds contained therein.

  15. Conversion of hydrocarbon fuel in thermal protection reactors of hypersonic aircraft

    NASA Astrophysics Data System (ADS)

    Kuranov, A. L.; Mikhaylov, A. M.; Korabelnikov, A. V.

    2016-07-01

    Thermal protection of heat-stressed surfaces of a high-speed vehicle flying in dense layers of atmosphere is one of the topical issues. Not of a less importance is also the problem of hydrocarbon fuel combustion in a supersonic air flow. In the concept under development, it is supposed that in the most high-stressed parts of airframe and engine, catalytic thermochemical reactors will be installed, wherein highly endothermic processes of steam conversion of hydrocarbon fuel take place. Simultaneously with heat absorption, hydrogen generation will occur in the reactors. This paper presents the results of a study of conversion of hydrocarbon fuel in a slit reactor.

  16. Chemistry Notes

    ERIC Educational Resources Information Center

    School Science Review, 1972

    1972-01-01

    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…

  17. Chemistry Notes.

    ERIC Educational Resources Information Center

    School Science Review, 1983

    1983-01-01

    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…

  18. Chemistry Notes.

    ERIC Educational Resources Information Center

    School Science Review, 1978

    1978-01-01

    Describes some laboratory apparatus, chemistry experiments and demonstrations, such as a Kofler block melting point apparatus, chromatographic investigation of the phosphoric acid, x-ray diffraction, the fountain experiment, endothermic sherbet, the measurement of viscosity, ionization energies and electronic configurations. (GA)

  19. Chemistry Notes.

    ERIC Educational Resources Information Center

    School Science Review, 1982

    1982-01-01

    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…

  20. Chemistry Notes.

    ERIC Educational Resources Information Center

    School Science Review, 1980

    1980-01-01

    Presents 12 chemistry notes for British secondary school teachers. Some of these notes are: (1) a simple device for testing pH-meters; (2) portable fume cupboard safety screen; and (3) Mass spectroscopy-analysis of a mass peak. (HM)

  1. Chemistry Notes

    ERIC Educational Resources Information Center

    School Science Review, 1976

    1976-01-01

    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…

  2. Chemistry Notes.

    ERIC Educational Resources Information Center

    School Science Review, 1983

    1983-01-01

    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;…

  3. Chemistry Notes

    ERIC Educational Resources Information Center

    School Science Review, 1972

    1972-01-01

    Short articles on the alkylation of aniline, the preparation and properties of perbromate, using scrap copper in chemistry instruction, a safe method of burning hydrogen, and the use of an ion-charge model as an alternative to the mole concept in secondary school instruction. (AL)

  4. Study of PAH emission from the solid fuels combustion in residential furnaces.

    PubMed

    Kakareka, Sergey V; Kukharchyk, Tamara I; Khomich, Valery S

    2005-01-01

    The procedure for and results of a test study of polycyclic aromatic hydrocarbon (PAH) emission from a few types of solid fuels combustion in residential furnaces of various designs typical for Belarus are discussed. Greatest levels of PAH emission were detected from domestic wastes and wood waste combustion. Lowest levels of PAH emission are from peat briquette combustion. It was found that PAH concentration in off-gases from firewood combustion also varies significantly depending on the type of wood: the highest values of PAH are typical for waste gases from birch firewood combustion in comparison with pine firewood combustion. Draft PAH emission factors are proposed with intended application for emission inventory of such installations. PMID:15519469

  5. [Retention of selenium volatility using lime in coal combustion].

    PubMed

    Zhang, J; Ren, D; Zhong, Q; Xu, F; Zhang, Y; Yin, J

    2001-05-01

    For understanding the volatility of selenium, the effect of the contents of exchangeable cations of coal on it, and the retention of selenium using CaO in coal combustion, the sequential chemistry extraction, the fixed bed and circulating fluidized bed (CFB) combustion, X-ray diffraction (XRD) and atomic fluorescence spectrometry (AFS) were undertaken. The results showed that the volatility of selenium was more than 97% in coal combustion at 815 degrees C, and the volatility of selenium was affected by the content of exchangeable cations of coal in low-middle temperature. It was identified that lime can restrain the volatility of selenium. In fixed bed combustion of coal, the retention rates of selenium volatility were between 11.6% and 50.7% using lime. In circulating fluidized bed combustion of coal, partitioning of selenium changed very much in ash of different size fraction between without lime and with lime. Comparing with combustion without lime, the content of selenium in ash from chimney was less than fourth times and that in leaching water from chimney decreased by two orders of magnitude using lime. Retention of selenium volatility using lime is so effective in coal combustion, especially in CFB combustion of coal. PMID:11507891

  6. Thermal cracking of hydrocarbons

    SciTech Connect

    Braun, R.L.; Burnham, A.K.

    1988-09-01

    Knowledge of thermal cracking of hydrocarbons is important in understanding and modeling petroleum maturation. We have reviewed the literature on the thermal cracking of pure hydrocarbons and mixtures of hydrocarbons, with particular attention given to dependence of the kinetics on temperature, pressure, and phase. Major uncertainties remain with regard to pressure dependence. Based on this review, we developed a simple, four-component, three-reaction model for oil-cracking. We also developed a simple, kerogen-maturation, kinetic model that incorporates hydrogen and carbon balance and includes the most important oil- and gas-forming reactions: kerogen pyrolysis, three oil-cracking reactions, and three coke-pyrolysis reactions. Tentative stoichiometry parameters are given for lacustrine and marine kerogens. 35 refs., 5 figs., 5 tabs.

  7. Fiber-Supported Droplet Combustion Experiment-2

    NASA Technical Reports Server (NTRS)

    Colantonio, Renato O.

    1998-01-01

    A major portion of the energy produced in the world today comes from the burning of liquid hydrocarbon fuels in the form of droplets. Understanding the fundamental physical processes involved in droplet combustion is not only important in energy production but also in propulsion, in the mitigation of combustion-generated pollution, and in the control of the fire hazards associated with handling liquid combustibles. Microgravity makes spherically symmetric combustion possible, allowing investigators to easily validate their droplet models without the complicating effects of gravity. The Fiber-Supported Droplet Combustion (FSDC-2) investigation was conducted in the Microgravity Glovebox facility of the shuttles' Spacelab during the reflight of the Microgravity Science Laboratory (MSL- 1R) on STS-94 in July 1997. FSDC-2 studied fundamental phenomena related to liquid fuel droplet combustion in air. Pure fuels and mixtures of fuels were burned as isolated single and duo droplets with and without forced air convection. FSDC-2 is sponsored by the NASA Lewis Research Center, whose researchers are working in cooperation with several investigators from industry and academia. The rate at which a droplet burns is important in many commercial applications. The classical theory of droplet burning assumes that, for an isolated, spherically symmetric, single-fuel droplet, the gas-phase combustion processes are much faster than the droplet surface regression rate and that the liquid phase is at a uniform temperature equal to the boiling point. Recent, more advanced models predict that both the liquid and gas phases are unsteady during a substantial portion of the droplet's burning history, thus affecting the instantaneous and average burning rates, and that flame radiation is a dominant mechanism that can extinguish flames in a microgravity environment. FSDC-2 has provided well-defined, symmetric droplet burning data including radiative emissions to validate these theoretical

  8. Simplified Modeling of Oxidation of Hydrocarbons

    NASA Technical Reports Server (NTRS)

    Bellan, Josette; Harstad, Kenneth

    2008-01-01

    A method of simplified computational modeling of oxidation of hydrocarbons is undergoing development. This is one of several developments needed to enable accurate computational simulation of turbulent, chemically reacting flows. At present, accurate computational simulation of such flows is difficult or impossible in most cases because (1) the numbers of grid points needed for adequate spatial resolution of turbulent flows in realistically complex geometries are beyond the capabilities of typical supercomputers now in use and (2) the combustion of typical hydrocarbons proceeds through decomposition into hundreds of molecular species interacting through thousands of reactions. Hence, the combination of detailed reaction- rate models with the fundamental flow equations yields flow models that are computationally prohibitive. Hence, further, a reduction of at least an order of magnitude in the dimension of reaction kinetics is one of the prerequisites for feasibility of computational simulation of turbulent, chemically reacting flows. In the present method of simplified modeling, all molecular species involved in the oxidation of hydrocarbons are classified as either light or heavy; heavy molecules are those having 3 or more carbon atoms. The light molecules are not subject to meaningful decomposition, and the heavy molecules are considered to decompose into only 13 specified constituent radicals, a few of which are listed in the table. One constructs a reduced-order model, suitable for use in estimating the release of heat and the evolution of temperature in combustion, from a base comprising the 13 constituent radicals plus a total of 26 other species that include the light molecules and related light free radicals. Then rather than following all possible species through their reaction coordinates, one follows only the reduced set of reaction coordinates of the base. The behavior of the base was examined in test computational simulations of the combustion of

  9. Are Aromatic Hydrocarbons Generated from the Atmospheric Oxidation of Biogenic Hydrocarbons?

    NASA Astrophysics Data System (ADS)

    Gratien, A.; Johnson, S. N.; Ezell, M. J.; Wingen, L. M.; Perraud, V. M.; Dawson, M.; Bennett, R.; Finlayson-Pitts, B. J.

    2010-12-01

    Biogenic volatile organic compounds (BVOCs) are estimated to account for approximately 90% of total hydrocarbon emissions. When released into the troposphere, these BVOC undergo chemical oxidation, e.g. by hydroxyl radicals (OH) and ozone (O3) during daytime, and by nitrate radicals (NO3) and ozone at night. Anthropogenic sources release into the troposphere a wide range of volatile organic compounds (VOC), also including aromatic hydrocarbons. Their major source is believed to be the combustion and the evaporation of the fuels. One question is while there are others sources of aromatics in air. For example, an aromatic hydrocarbon, p-cymene, was recently reported in air above a forest canopy that had significant emissions of terpenes (isoprene, α-pinene, β-pinene, limonene…), and its concentration increased as a function of altitude, suggesting its possible formation in the atmosphere. The goal of the present study was to determine whether p-cymene can be generated from reactions of biogenic hydrocarbons in air. The oxidations of isoprene, α-pinene, β-pinene and limonene by O3, NO3 and OH have been studied at 1 atm air under dry conditions, at high relative humidity (70% RH), or with deliquesced sodium bisulfate (acid source) on the walls of a Teflon reaction chamber. A search for the generation of aromatic hydrocarbons products was made using GC-MS and PTR-MS. p-cymene has been observed from the reactions of α-pinene and limonene. Possible mechanisms will be presented and the atmospheric implications discussed.

  10. Hydrocarbon fuel detergent

    SciTech Connect

    Meyer, G.R.; Lyons, W.R.

    1990-01-23

    This patent describes a hydrocarbon fuel composition comprising: a hydrocarbon fuel; and a detergent amount of a detergent comprising an alkenylsuccinimide prepared by reacting an alkenylsuccinic acid or anhydride with a mixture of amines, wherein at least 90 weight percent of the alkenyl substituent is derived from an olefin having a carbon chain of from 10 to 30 carbons or mixtures thereof, and wherein the alkenylsuccinic acid or anhydride is reacted with the mixture of amines at a mole ratio of 0.8 to 1.5 moles of the amines per mole of the alkenylsuccinic acid or anhydride.

  11. Quantitative Hydrocarbon Surface Analysis

    NASA Technical Reports Server (NTRS)

    Douglas, Vonnie M.

    2000-01-01

    The elimination of ozone depleting substances, such as carbon tetrachloride, has resulted in the use of new analytical techniques for cleanliness verification and contamination sampling. The last remaining application at Rocketdyne which required a replacement technique was the quantitative analysis of hydrocarbons by infrared spectrometry. This application, which previously utilized carbon tetrachloride, was successfully modified using the SOC-400, a compact portable FTIR manufactured by Surface Optics Corporation. This instrument can quantitatively measure and identify hydrocarbons from solvent flush of hardware as well as directly analyze the surface of metallic components without the use of ozone depleting chemicals. Several sampling accessories are utilized to perform analysis for various applications.

  12. Fifteenth combustion research conference

    SciTech Connect

    1993-06-01

    The BES research efforts cover chemical reaction theory, experimental dynamics and spectroscopy, thermodynamics of combustion intermediates, chemical kinetics, reaction mechanisms, combustion diagnostics, and fluid dynamics and chemically reacting flows. 98 papers and abstracts are included. Separate abstracts were prepared for the papers.

  13. ASRM combustion instability studies

    NASA Technical Reports Server (NTRS)

    Strand, L. D.

    1992-01-01

    The objectives of this task were to measure and compare the combustion response characteristics of the selected propellant formulation for the Space Shuttle Advanced Solid Rocket Motor (ASRM) with those of the current Redesigned Solid Rocket Motor (RSRM) formulation. Tests were also carried out to characterize the combustion response of the selected propellant formulation for the ASRM igniter motor.

  14. Coal Combustion Science

    SciTech Connect

    Hardesty, D.R.; Fletcher, T.H.; Hurt, R.H.; Baxter, L.L. )

    1991-08-01

    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 Direct Utilization Advanced Research and Technology Development Program, and the International Energy Agency Coal Combustion Science Project. Specific tasks for this activity include: (1) coal devolatilization - the objective of this risk is to characterize the physical and chemical processes that constitute the early devolatilization phase of coal combustion as a function of coal type, heating rate, particle size and temperature, and gas phase temperature and oxidizer concentration; (2) coal char combustion -the objective of this task is to characterize the physical and chemical processes involved during coal char combustion as a function of coal type, particle size and temperature, and gas phase temperature and oxygen concentration; (3) fate of mineral matter during coal combustion - the objective of this task is to establish a quantitative understanding of the mechanisms and rates of transformation, fragmentation, and deposition of mineral matter in coal combustion environments as a function of coal type, particle size and temperature, the initial forms and distribution of mineral species in the unreacted coal, and the local gas temperature and composition.

  15. Optical measurements of hydrocarbons emitted from a simulated crevice volume in an engine

    SciTech Connect

    Medina, S.C.; Green, R.M.; Smith, J.R.

    1984-01-01

    The process of hydrocarbon emission from an engine crevice was simulated in an operating research engine by the introduction of a small tube into the combustion chamber. This simulated crevice volume was used to determine the fate of unburned hydrocarbons that interact with the crevice. Shadowgraph photography and spontaneous Raman spectroscopy were used to determine flow patterns, temperatures, and hydrocarbon concentrations 1 mm from the tube opening. Hydrocarbon species were first detected at the tube exit late in the expansion stroke, long after the start of outflow from the simulation volume. A flame was never observed near the tube exit. Unburned hydrocarbons exiting the tube did not undergo rapid oxidation at temperatures up to 1400 Kelvins. 21 references, 11 figures.

  16. Optical measurements of hydrocarbons emitted from a simulated crevice volume in an engine

    SciTech Connect

    Medina, S.C.; Green, R.M.; Smith, J.R.

    1984-01-01

    The process of hydrocarbon emission from an engine crevice was simulated in an operating research engine by the introduction of a small tube into the combustion chamber. This simulated crevice volume was used to determine the fate of unburned hydrocarbons that interact with the crevice. Shadowgraph photography and spontaneous Raman spectroscopy were used to determine flow patterns, temperatures, and hydrocarbon concentrations 1 mm from the tube opening. Hydrocarbon species were first detected at the tube exit late in the expansion stroke, long after the start of outflow from the simulation volume. A flame was never observed near the tube exit. Unburned hydrocarbons exiting the tube did not undergo rapid oxidation at temperatures up to 1400 Kelvins.

  17. Fuel-rich catalytic combustion of a high density fuel

    NASA Technical Reports Server (NTRS)

    Brabbs, Theodore A.; Merritt, Sylvia A.

    1993-01-01

    Fuel-rich catalytic combustion (ER is greater than 4) of the high density fuel exo-tetrahydrocyclopentadiene (JP-10) was studied over the equivalence ratio range 5.0 to 7.6, which yielded combustion temperatures of 1220 to 1120 K. The process produced soot-free gaseous products similar to those obtained with iso-octane and jet-A in previous studies. The measured combustion temperature agreed well with that calculated assuming soot was not a combustion product. The process raised the effective hydrogen/carbon (H/C) ratio from 1.6 to over 2.0, thus significantly improving the combustion properties of the fuel. At an equivalence ratio near 5.0, about 80 percent of the initial fuel carbon was in light gaseous products and about 20 percent in larger condensable molecules. Fuel-rich catalytic combustion has now been studied for three fuels with H/C ratios of 2.25 (iso-octane), 1.92 (jet-A), and 1.6 (JP-10). A comparison of the product distribution of these fuels shows that, in general, the measured concentrations of the combustion products were monotonic functions of the H/C ratio with the exception of hydrogen and ethylene. In these cases, data for JP-10 fell between iso-octane and jet-A rather than beyond jet-A. It is suggested that the ring cross-linking structure of JP-10 may be responsible for this behavior. All the fuels studied showed that the largest amounts of small hydrocarbon molecules and the smallest amounts of large condensable molecules occurred at the lower equivalence ratios. This corresponds to the highest combustion temperatures used in these studies. Although higher temperatures may improve this mix, the temperature is limited. First, the life of the present catalyst would be greatly shortened when operated at temperatures of 1300 K or greater. Second, fuel-rich catalytic combustion does not produce soot because the combustion temperatures used in the experiments were well below the threshold temperature (1350 K) for the formation of soot. Increasing

  18. Chemistry of the outer planets

    NASA Technical Reports Server (NTRS)

    Scattergood, Thomas W.

    1992-01-01

    Various aspects were studied of past or present chemistry in the atmospheres of the outer planets and their satellites using lab simulations. Three areas were studied: (1) organic chemistry induced by kinetically hot hydrogen atoms in the region of Jupiter's atmosphere containing the ammonia cirrus clouds; (2) the conversion of NH3 into N2 by plasmas associated with entry of meteors and other objects into the atmosphere of early Titan; and (3) the synthesis of simple hydrocarbons and HCN by lightning in mixtures containing N2, CH4, and NH3 representing the atmospheres of Titan and the outer planets. The results showed that: (1) hot H2 atoms formed from the photodissociation of NH3 in Jupiter's atmosphere could account for some of the atmospheric chemistry in the ammonia cirrus cloud region; (2) the thermalization of hot H2 atoms in atmospheres predominated by molecular H is not as rapid as predicted by elastic collision theory; (3) the net quantum loss of NH3 in the presence of a 200 fold excess of H2 is 0.02, much higher than was expected from the amount of H2 present; (4) the conversion of NH3 into N2 in plasmas associated with infalling meteors is very efficient and rapid, and could account for most of the N2 present on Titan; (5) the yields of C2H2 and HCN from lightning induced chemistry in mixtures of CH4 and N2 is consistent with quenched thermodynamic models of the discharge core; and (6) photolysis induced by the UV light emitted by the gases in the hot plasmas may account for some, if not most, of the excess production of C2H6 and the more complex hydrocarbons.

  19. The relationship between hydrocarbon and stratabound metal sulfide deposits: The Upper Smackover as an analog

    SciTech Connect

    Denham, M.E. )

    1991-03-01

    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.

  20. Electronic spectroscopy of transient species in solid neon: the indene-motif polycyclic hydrocarbon cation family C9Hy(+) (y = 7-9) and their neutrals.

    PubMed

    Nagy, Adam; Garkusha, Iryna; Fulara, Jan; Maier, John P

    2013-11-28

    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