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1

Theoretical studies of hydrocarbon combustion chemistry. Annual progress report  

SciTech Connect

The author reports here the results of DZP CISD calculations for methylcarbene. Geometry, symmetry, and vibrational modes for the radical are reported for both the singlet and the triplet state. Future work will focus on the ethyl radical-oxygen interaction relevant to hydrocarbon combustion.

Schaefer, H.F. III

1994-08-01

2

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

SciTech Connect

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

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

2006-10-15

3

Combustion of viscous hydrocarbons  

Microsoft Academic Search

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° API or less, viscosity of about 1000 centipoise or greater at 212°F., a paraffin

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

1987-01-01

4

Combustion of viscous hydrocarbons  

SciTech Connect

A method is described for utilizing viscous hydrocarbons as combustible fuels comprising: (A) forming a hydrocarbosol using a surfactant package in a proportion of about 1:100 to about 1:20,000 by weight based on hydrocarbon, (1) the surfactant package comprising (a) at least one water-soluble surfactant, an effective amount of which surfactant promotes emulsification of a hydrocarbon with API gravity of about 20/sup 0//sup o/ API or less; and (b) at least one water-soluble bioemulsifier, being a microboally-derived substance which predominantly resides at hydrocarbon/water interfaces to substantially surround hydrocarbon droplets in hydrocarbon-in-water emulsions; (2) the hydrocarbosol (a) comprising a hydrocarbon characterized by an API gravity of about 20/sup 0//sup o/ API or less; (b) having a hydrocarbon:water ratio of about 70:30 by volume; and (B) burning the resultant hydrocarbosol.

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

1986-10-21

5

Combustion of viscous hydrocarbons  

Microsoft Academic Search

A method is described for utilizing viscous hydrocarbons as combustible fuels comprising: (A) forming a hydrocarbosol using a surfactant package in a proportion of about 1:100 to about 1:20,000 by weight based on hydrocarbon, (1) the surfactant package comprising (a) at least one water-soluble surfactant, an effective amount of which surfactant promotes emulsification of a hydrocarbon with API gravity of

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

1986-01-01

6

Combustion of viscous hydrocarbons  

SciTech Connect

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.

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

1987-08-04

7

Combustion Hydrodynamics and Chemistry.  

National Technical Information Service (NTIS)

Accomplishments in combustion hydrodynamics and chemistry studies consisted of a computational study of the chemical kinetics of hydrogen combustion along with some subsidiary studies and programming. Comparisons with experimental results have been genera...

E. Hyman

1981-01-01

8

The chemistry of combustion of organophosphorus compounds  

NASA Astrophysics Data System (ADS)

The current state of studies into combustion of organophosphorus compounds (OPC) is presented. The chemical processes occurring in flames upon introduction of OPC additives, the mechanisms of their transformations and influence on the combustion rate and the structure and propagation limits of hydrogen and hydrocarbon flames are considered. The key results of experimental and theoretical studies and simulation of the combustion chemistry of hydrogen and hydrocarbon mixed and diffusion flames with and without OPC are described. The mechanism of flame promotion and inhibition by OPC is analysed. The prospects of practical applications of phosphorus compounds as flame-arresters are evaluated. The OPC toxicity and environmental impact are discussed.

Korobeinichev, O. P.; Shvartsberg, V. M.; Shmakov, A. G.

2007-11-01

9

Assessment of combustion submodels for turbulent nonpremixed hydrocarbon flames  

Microsoft Academic Search

Data bases generated by direct numerical simulation (DNS) of nonpremixed combustion are used to evaluate stationary laminar flamelet and conditional moment closure (CMC) models of turbulent combustion. The chemical kinetics used for the simulation and modeling is a systematically reduced two-step mechanism for hydrocarbon combustion. Heat release effects on the chemistry are included but a constant density assumption is used.

N. Swaminathan; R. W. Bilger

1999-01-01

10

Hydrocarbon Fouling of SCR during PCCI combustion  

SciTech Connect

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

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

2012-01-01

11

Nitrous oxide combustion chemistry  

SciTech Connect

To gain improved understanding of N2O combustion chemistry, experimentation and numerical modeling were performed, and are described. Principal conclusions are: (1) N2O emission is quite temperature dependent, and (2) for lean, homogeneous combustion systems with peak temperatures higher than 1200 K and without rapid cooling, N2O emission is low. Thermochemical property variations have substantial effects on calculated species profiles. Changes in enthalpies of formation of NH, NH2, and NNH resulted in large differences in predicted NO, N2, and N2O concentrations. Measurements were made in lean, premixed, and atmospheric pressure flat flames by microprobe sampling and gas chromatographic or chemiluminescence analysis. With 2000 ppm of either NH3, NO, or N2O added to the reactants, N2O was observed at moderate concentrations near the burner surface, and a monotonically decreasing concentrations downstream. With NH3 as dopant, early- and post-flame N2O concentration varied inversely with temperature, as did its decay rate. With N2O as dopant, product branching to NO and N2 was 8 and 92 percent. Sensitivity and rate data indicated the primary N2O formation and destruction reactions to be NH + NO = N2O + H and H + N2O = N2 + OH, and that H + O2 + M = HO2 + M plays an important role in trapping H atoms to enhance N2O survival. Flash-ignited combustion experiments were performed and studied. A mixture, where NH3 was primary photolysis absorber and fuel species, burned inhomogeneously. Concentration profiles of N2, NO, O2, and N2O were recorded. N2O added to the reactants disappeared during combustion. Post-flame NO and N2 concentrations were higher than previously reported NH3 flames, but their ratio agreed well with earlier results.

Martin, R.J.

1989-01-01

12

Coal combustion chemistry correlation aspects  

Microsoft Academic Search

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

Badin

1984-01-01

13

Determining Heats of Combustion of Gaseous Hydrocarbons  

NASA Technical Reports Server (NTRS)

Enrichment-oxygen flow rate-ratio related to heat of combustion. Technique developed for determining heats of combustion of natural-gas samples. Based on measuring ratio m/n, where m is (volmetric) flow rate of oxygen required to enrich carrier air in which test gas flowing at rate n is burned, such that mole fraction of oxygen in combustion-product gases equals that in carrier air. The m/n ratio directly related to heats of combustion of saturated hydrocarbons present in natural gas.

Singh, Jag J.; Sprinkle, Danny R.; Puster, Richard L.

1987-01-01

14

Odorization of combustible hydrocarbon gases  

SciTech Connect

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

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

1984-12-11

15

Combustion chemistry of solid propellants  

NASA Technical Reports Server (NTRS)

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.

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

1974-01-01

16

Chemistry in Titan's Hydrocarbon Seas  

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

17

LOX/Hydrocarbon Combustion Instability Investigation  

NASA Technical Reports Server (NTRS)

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.

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

1989-01-01

18

Combustion of hydrocarbons in purified fluorine  

SciTech Connect

Emission spectra and ionization are compared in premixed flames of CH/sub 4/ burning in commercial F/sub 2/(0.4% O/sub 2/) with those burning in purified F/sub 2/. Oxygen impurity is reduced to below 0.02% in the purified F/sub 2/ by reaction with SbF/sub 5/. No appreciable differences exist between the spectra of flames burning in commercial and purified F/sub 2/; both are dominated by bands of CHF and CH. CH emission is thus an intrinsic property of F/sub 2/-hydrocarbon combustion. In contrast, ionization (as measured by a Langmuir probe) is reduced to an undetectable level in flames with purified F/sub 2/ and is roughly proportional to O/sub 2/ concentration in flames with unpurified F/sub 2/. Ionization is thus not an inherent property of F/sub 2/-hydrocarbon combustion.

Jones, D.; Kaufman, M.

1987-03-01

19

Theory and modeling in combustion chemistry.  

National Technical Information Service (NTIS)

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

J. A. Miller

1996-01-01

20

Catalytic combustion of hydrocarbons over perovskites  

Microsoft Academic Search

The advantages and disadvantages of the catalysts so far employed or proposed for the low temperature catalytic combustion of hydrocarbons, in both static and mobile energy production devices, are discussed. Furthermore, a La0.9Ce0.1CoO3? perovskite has been prepared by a recently proposed new flame-hydrolysis (FH) method. This proved a high surface area, thermally highly resistant catalyst. The partial substitution of Ce

Lucio Forni; I Rossetti

2002-01-01

21

Characteristics and combustion of future hydrocarbon fuels  

NASA Technical Reports Server (NTRS)

Changes in fuel properties that are expected in future hydrocarbon fuels for aircraft are discussed along with the principal properties of 'syncrudes' and the fuels that can be derived from them. 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.

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

1978-01-01

22

COLDSTART ENGINE COMBUSTION MODELLING TO CONTROL HYDROCARBON EMISSIONS  

Microsoft Academic Search

Due to the large contribution of the coldstart process to unburned hydrocarbon emissions of an internal combustion engine during FTP cycle tests, we take a new look at the production of hydrocarbons inside the combustion chamber during coldstart. To this end a model is developed which predicts the exhaust port hydrocarbon concentration, exhaust gas temperature and equivalence ratio based on

Byron T. Shaw II; J. Karl Hedrick

23

Detailed and reduced chemical-kinetic descriptions for hydrocarbon combustion  

NASA Astrophysics Data System (ADS)

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

Petrova, Maria V.

24

Contemplation on the heats of combustion of isomeric hydrocarbons  

Microsoft Academic Search

Within the Hckel molecular orbital theory, the heats of combustion of isomeric hydrocarbons are related to some topological factors. The standard heats of combustion values of alternant hydrocarbons, expressed as kcal\\/g, seem to be related to a4 coefficient of their secular polynomials.

Lemi Trker

2004-01-01

25

Basic Considerations in the Combustion of Hydrocarbon Fuels with Air  

NASA Technical Reports Server (NTRS)

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.

Barnett, Henry C; Hibbard, Robert R

1957-01-01

26

Sulphur Chemistry in Combustion II  

Microsoft Academic Search

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

J. E. Johnsson; S. Kiil

27

Efficient Implementation of Chemistry in Computational Combustion  

Microsoft Academic Search

For hydrocarbon fuels, detailed chemical kinetics typically involve a large number of chemical species and reactions. In a\\u000a high-fidelity combustion calculation, it is essential, though challenging, to incorporate sufficiently detailed chemical kinetics\\u000a to enable reliable predictions of thermo-chemical quantities, especially for pollutants such as NO\\u000a \\u000a x\\u000a and CO. In this paper, we review the recent work on efficient implementation of

Stephen B. Pope; Zhuyin Ren

2009-01-01

28

Biofuel combustion chemistry: from ethanol to biodiesel.  

PubMed

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

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

2010-05-10

29

Detailed chemical kinetic models for the combustion of hydrocarbon fuels  

Microsoft Academic Search

The status of detailed chemical kinetic models for the intermediate to high-temperature oxidation, ignition, combustion of hydrocarbons is reviewed in conjunction with the experiments that validate them.All classes of hydrocarbons are covered including linear and cyclic alkanes, alkenes, alkynes as well as aromatics.

John M. Simmie

2003-01-01

30

Filtration Combustion in Hydrocarbon Desorption from a Porous Medium  

Microsoft Academic Search

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

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

2003-01-01

31

Combustion of hydrocarbon fuels within porous inert media  

Microsoft Academic Search

There has been a recent surge of interest in the combustion of hydrocarbon fuels within porous inert media. The interest has been directed by the needs of industry to develop high performance radiant heaters while complying with increasingly stringent emissions regulations. This paper reviews the processes associated with non-catalytic combustion within porous media, and describes related experimental and modeling research.

J. R. Howell; M. J. Hall; J. L. Ellzey

1996-01-01

32

Theory and modeling in combustion chemistry  

SciTech Connect

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

Miller, J.A.

1996-10-01

33

Lox/Hydrocarbon Combustion and Cooling Survey.  

National Technical Information Service (NTIS)

Liquid oxygen (LOX) and hydrocarbon fuels (methane, propane, and RP-1) are very attractive for booster rocket engine applications because of their high bulk density and respectful performance. Vehicle payload capability is dependent on the attainable engi...

R. T. Cook F. M. Kirby

1986-01-01

34

Chemistry and Transport Properties for Jet Fuel Combustion.  

National Technical Information Service (NTIS)

Combustion modeling is an essential tool for the prediction of flame characteristics as well as for the optimal design of combustors. Although, chemical kinetic mechanisms of hydrocarbons have been widely studied, molecular transport data of those species...

A. Violi

2013-01-01

35

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.[Taken from https://www-pls.llnl.gov/?url=science_and_technology-chemistry-combustion

36

A simplified hydrocarbon reaction mechanism for combustion applications  

NASA Technical Reports Server (NTRS)

A simplified chemical kinetic reaction mechanism for the combustion of a hydrocarbon fuel is presented and discussed. The observed kinetic behavior of propane combustion as determined in shock tube studies and the calculated kinetic behavior of propane/air mixtures as derived from a detailed propane combustion mechanism were used as a data base for constructing and refining the mechanism. The mechanism contains 13 chemical species and 26 chemical reactions. Numerical studies revealed that the simplified mechanism can reproduce the observed kinetic behavior of propane/air mixtures, including laminar flame speeds, over a wide range of temperatures and pressures. It is anticipated that the mechanism can be used in various combustion applications and provide a more realistic description of the combustion process than can be achieved using global reaction mechanisms.

Jachimowski, C. J.

1985-01-01

37

Microwave enhanced combustion of laminar hydrocarbon flame fronts  

Microsoft Academic Search

The X-43 missions in 2005 demonstrated the feasibility of a hydrogen fueled scramjet. Since that time, the cost, performance, and safety concerns surrounding the use of hydrogen have motivated researchers to investigate methods of enhancing the performance of easily stored hydrocarbon based fuels by improving their ignition, flammability, and flameholding characteristics. The microwave enhanced combustion testbed has demonstrated a significant

Emanuel Solomon Stockman

2009-01-01

38

Forward in situ combustion method for recovering hydrocarbons with production well cooling  

Microsoft Academic Search

A method is described for the recovery of hydrocarbons, by forward in situ combustion, from a subterranean formation employing production well cooling. An in situ combustion front is moved by the injection of oxygen-containing gas into the formation through an injection well toward a spaced production well. The front displaces combustion-generated heated fluids, and formation fluid containing combustible hydrocarbons, into

Sharp

1968-01-01

39

Laser probes of propellant combustion chemistry. Final report 30 Sep 80-31 Jan 84  

SciTech Connect

Laser-induced fluorescence (LIF) can be used to measure the atomic, diatomic, and triatomic free radicals that are the intermediates in combustion chemistry. Coupled with detailed models, which incorporate a sound and consistent set of reaction rate constants, such measurements can lead to an understanding of that chemistry, having predictive value for use under experimentally difficult conditions. This report describes the development of LIF techniques, the applications of such techniques of flames and to laser pyrolysis/laser fluorescence kinetics experiments, studies of rate constant estimations and detailed modeling of combustion chemistry. The chemistry studied is that of combusting mixtures of CH4/N2O, CH2O/N2O, CH2O/NO2, and related compounds. These contain the chemical networks, individual reactions, and radical species present in the gas-phase combustion of nitramine propellants, such as HMX and RDX. The tasks described are LIF diagnostic studies on O, N, OH, NCO, and NH2 in flow systems and flames, rate constant estimation studies for unimolecular decomposition of CH2O and several hydrocarbons, modelling of the CH2O/N2O flame, and laser pyrolysis/laser fluorescence studies of CH4/N2O and CH2O/N2O chemistry.

Crosley, D.R.; Smith, G.P.; Golden, D.M.

1984-03-29

40

Combustion of halogenated hydrocarbons with heat recovery  

Microsoft Academic Search

This patent describes a water-cooled, horizontal fire-tube boiler having an affixed end section, a boiler section, and a second end section, which comprises in combination: (a) a boiler section comprising a generally closed shell having a vertically disposed metal tube-sheet at each end, the shell holding water between the ends, a relatively long secondary combustion chamber extending along the length

Buice

1986-01-01

41

New method for determining heats of combustion of gaseous hydrocarbons  

NASA Technical Reports Server (NTRS)

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.

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

1985-01-01

42

High temperature chemistry of aromatic hydrocarbons.  

National Technical Information Service (NTIS)

We have not only gained new insight into the mechanism and generality of Polycyclic Aromatic Hydrocarbon (PAH) thermal automerization reactions, we have also uncovered several new high temperature reactions and added a third dimension to our program by ap...

L. T. Scott

1991-01-01

43

Hydrocarbon-fuel/combustion-chamber-liner materials compatibility  

NASA Technical Reports Server (NTRS)

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.

Gage, Mark L.

1990-01-01

44

Fireball during combustion of hydrocarbon fueld releases II. Thermal radiation  

Microsoft Academic Search

The processes of radiative heat transfer in a fireball which develops upon ignition of a cloud of hydrocarbon fuel near the\\u000a Earths surface are simulated numerically. The emissive characteristics of combustion products (mixtures of nitrogen dioxide,\\u000a water vapor, and soot) are described using the weighted-sum-of-gray-gases model with temperature-dependent weighting coefficients.\\u000a The radiation field in the fireball for individual gray gases

G. M. Makhviladze; J. P. Roberts; S. E. Yakush

1999-01-01

45

Mach 2 combustion characteristics of hydrogen\\/hydrocarbon fuel mixtures  

Microsoft Academic Search

The combustion of H\\/CH and H\\/CH 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

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

1987-01-01

46

ShockTube Combustion of High Density Hydrocarbon Fuels  

Microsoft Academic Search

Shock-tube techniques have been used to determine rates of carbon dioxide production in shock-wave heated mixtures of oxygen and hydrogenated dimers of bicycloheptadiene, components of the high density fuel RJ-S. Reaction profiles generated by this method have demonstrated that the combustion rate of the hydrocarbon vapors increases with fuel and oxygen concentration, but is not affected by the total pressure

J. M. BRUPBACHER; M. T. McCALL; M. McCARTY Jr

1978-01-01

47

Polynuclear aromatic hydrocarbons: Chemistry, characterization and carcinogenesis  

SciTech Connect

This book contains 75 selections. Some of the titles are: Polycyclic Aromatic Hydrocarbons in Cancer Research, Photolysis of PAH Absorbed on Silica Gel and Fly ASh, Phenotyping Cytochromes P-450 with Monoclonal Antibodies, Leaching of PAH from Industrial Wastes with Municipal Waste Leachate, and Determinants of the Potencies of Carcinogenic Mineral Oils.

Cooke, M.; Dennis, A.J.

1986-01-01

48

Hydrocarbon combustion enhancement by applied electric field and plasma kinetics  

NASA Astrophysics Data System (ADS)

Hydrocarbon flame speed and flame structure modifications have been studied using a low dc applied electric field opposing the gas flow directions. Our electrode configuration leads to a relatively high conduction current with a low applied voltage drop in the flame that permits to collect ~1011 cm-3 chemi-ion density at the pre-heat flame zone, which seems to simulate DBDs and other plasma assisted combustion enhancement conditions. The dissociative recombination of major positive chemi-ions H3O+ and HCO+ produces 1011 cm-3 H, O and OH radicals modifying both combustion kinetics and fluidics. Also, flame electrical conductivity measurement was found to correlate very well with the CH, OH and C2 chemiluminescence intensity fluctuations.

Ganguly, B. N.

2007-12-01

49

Explosion-induced combustion of hydrocarbon clouds in a chamber  

SciTech Connect

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

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

2001-02-06

50

Classics in Hydrocarbon Chemistry: Syntheses, Concepts, Perspectives (by Henning Hopf)  

NASA Astrophysics Data System (ADS)

What makes the book such a delight is that the reader can sense the joy and excitement that motivated the original researchers. This is summed up in a paragraph from Hopf (with a gratuitous comment about gender, which, if true, perhaps will not be true when a second edition appears):

There is one final reason why the study of hydrocarbons attracts many chemiststheir wish to play is often fulfilled extremely well on this exciting playing ground of organic chemistry. Whether (the mostly male) practitioners speak of tinker toy chemistry, molecular Lego or Meccano sets, the connection to an earlier part of their lives is obvious enough.

Magid, Ronald M.

2002-01-01

51

Sodium and sulfur chemistry in combustion gases.  

National Technical Information Service (NTIS)

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

R. Backman

1989-01-01

52

Investigation of the combustion kinetics and polycyclic aromatic hydrocarbon emissions from polycaprolactone combustion.  

PubMed

Polycaprolactone (PCL) is one of the most attractive biodegradable plastics that has been widely used in medicine and agriculture fields. Because of the large increase in biodegradable plastics usage, the production of waste biodegradable plastics will be increasing dramatically, producing a growing environmental problem. Generally, waste PCL is collected along with municipal solid wastes and then incinerated. This study investigates the combustion kinetics and emission factors of 16 US Environmental Protection Agency (EPA) priority polycyclic aromatic hydrocarbons (PAHs) in the PCL combustion. Experimentally, two reactions are involved in the PCL combustion process, possibly resulting in the emission of carbon dioxide, propanal, protonated caprolactone and very small amounts of PAH produced by incomplete combustion. The intermediate products may continuously be oxidized to form CO2. The emission factors for 16 US EPA priority PAHs are n.d. -2.95 microg/g, which are much lower than those of poly lactic acid and other plastics combustion. The conversion of PCL is 100%. Results from this work suggest that combustion is a good choice for the waste PCL disposal. PMID:23530325

Chien, Y C; Yang, S H

2013-01-01

53

Mach 2 combustion characteristics of hydrogen/hydrocarbon fuel mixtures  

NASA Technical Reports Server (NTRS)

The combustion of H2/CH4 and H2/C2H4 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 H2/C2H4 is shown to burn much more efficiently than H2/CH4, with no pilot-off blowout equivalence ratios greater than 0.5. It is suggested that H2/hydrocarbon mixtures are feasible fuels (at least in terms of combustion efficiency) for scramjet SSTO vehicles operating at freestream Mach numbers above 4.

Diskin, Glenn S.; Jachimowski, C. J.; Northam, G. Burton; Bell, Randy A.

1987-01-01

54

Mach 2 combustion characteristics of hydrogen/hydrocarbon fuel mixtures  

NASA Technical Reports Server (NTRS)

The combustion of H2/CH4 and H2/C2H4 mixtures containing 10-70 vol pct hydrocarbon at cumbustor inlet Mach number 2 and temperatures 2000-4000 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 H2/C2H4 is shown to burn much more efficiently than H2/CH4, with no pilot-off blowout at equivalence ratios greater than 0.5. It is suggested that H2/hydrocarbon mixtures are feasible fuels (at least in terms of combustion efficiency) for scramjet SSTO vehicles operating at freestream Mach numbers above 4.

Diskin, Glenn S.; Northam, G. Burton; Bell, Randy A.

1987-01-01

55

A small detailed chemical-kinetic mechanism for hydrocarbon combustion  

SciTech Connect

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)

Petrova, M.V.; Williams, F.A. [Center for Energy Research, Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA 92093 (United States)

2006-02-01

56

Microwave enhanced combustion of laminar hydrocarbon flame fronts  

NASA Astrophysics Data System (ADS)

The X-43 missions in 2005 demonstrated the feasibility of a hydrogen fueled scramjet. Since that time, the cost, performance, and safety concerns surrounding the use of hydrogen have motivated researchers to investigate methods of enhancing the performance of easily stored hydrocarbon based fuels by improving their ignition, flammability, and flameholding characteristics. The microwave enhanced combustion testbed has demonstrated a significant increase in the laminar flame speed of a premixed CH4/air flame when 1.3 kW continuous wave (CW) microwave radiation is directed at the flame front in a high-Q resonant cavity. The main aspect of the research aimed to accurately quantify key combustion parameters in the microwave enhanced flame using laser diagnostics for improved spatial resolution and accuracy over invasive probe devices. Particle image velocimetry (PIV), filtered Rayleigh scattering (FRS), and planar laser induced fluorescence (PLIF) were used to measured flame speed, temperature, and OH radical concentrations, respectively. The PIV and FRS laser experiments measured increases in flame speed up to 20% and a deposition of only 30 W of microwave power into the flame. The temperature measurements show an increase of temperature within the flame front as well as in the post flame region that are not of large enough magnitude to account for the flame speed increase via simple joule heating. Alongside PLIF measurements of an enhanced concentration of OH in the flame zone, these results imply that the microwave enhanced combustion was a combined thermal joule heating and non-equilibrium interaction. By replacing the CW microwave source with a pulsed magnetron that is capable of generating 1 mus wide, 30 kW peak power pulses at 1000 pulses per second, similar flame speed enhancements were achieved with 40 times less power. This effort provides the first realistic approach towards incorporating the microwave enhanced combustion concept into a scramjet combustor.

Stockman, Emanuel Solomon

57

A filtered tabulated chemistry model for LES of premixed combustion  

SciTech Connect

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

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

2010-03-15

58

Combustion chemistry and an evolving transportation fuel environment.  

SciTech Connect

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.

Taatjes, Craig A. (Org. 8353, Combustion Chemistry Department)

2010-05-01

59

On-Line Measurement of Heat of Combustion of Gaseous Hydrocarbon Fuel Mixtures  

NASA Technical Reports Server (NTRS)

A method for the on-line measurement of the heat of combustion of gaseous hydrocarbon fuel mixtures has been developed and tested. The method involves combustion of a test gas with a measured quantity of air to achieve a preset concentration of oxygen in the combustion products. This method involves using a controller which maintains the fuel (gas) volumetric flow rate at a level consistent with the desired oxygen concentration in the combustion products. The heat of combustion is determined form a known correlation with the fuel flow rate. An on-line computer accesses the fuel flow data and displays the heat of combustion measurement at desired time intervals. This technique appears to be especially applicable for measuring heats of combustion of hydrocarbon mixtures of unknown composition such as natural gas.

Sprinkle, Danny R.; Chaturvedi, Sushil K.; Kheireddine, Ali

1996-01-01

60

Relationships between Laboratory and Pilot-Scale Combustion of Some Chlorinated Hydrocarbons.  

National Technical Information Service (NTIS)

Factors governing the occurrence of trace amounts of residual organic substance emissions (ROSEs) in full-scale incinerators are not fully understood. Pilot-scale spray combustion experiments involving some liquid chlorinated hydrocarbons (CHCs) and the d...

D. P. Y. Chang N. W. Sorbo C. K. Law R. R. Steeper M. K. Richards

1989-01-01

61

Calculation of the Heat of Combustion of Hydrocarbon Components of Fuels  

Microsoft Academic Search

Development is continued of the empirical method for the calculation of the heat of combustion of organic compounds and, in particular, of hydrocarbons of different structures by the additive scheme based on their chemical structure.

E. V. Sagadeev; V. V. Sagadeev

2004-01-01

62

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

Microsoft Academic Search

This invention relates to liquid-hydrocarbon jet fuels and more particularly to azido additives to liquid-hydrocarbon ramjet fuels. In most liquid-fueled combustors such as the ramjet, the fuel is directly introduced into the upstream flow section of the combustion chamber in the form of sprays of droplets. These droplets subsequently mix with the external gas, heat up, gasify, combust, and thereby

1986-01-01

63

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

SciTech Connect

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

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

2011-01-01

64

Carbon deposition model for oxygen-hydrocarbon combustion, volume 1  

NASA Technical Reports Server (NTRS)

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.

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

1987-01-01

65

Carbon Deposition Model for Oxygen-Hydrocarbon Combustion, Volume 2  

NASA Technical Reports Server (NTRS)

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.

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

1987-01-01

66

An experimental apparatus for the study of the heat transfer and combustion characteristics of hydrocarbons  

Microsoft Academic Search

An experimental apparatus is described which has been designed for studying the combustion characteristics of the thermochemical reaction products of hydrocarbon fuels and heat transfer. The apparatus consists of a combustion chamber, air and fuel systems, a thermochemical reaction and thermostabilization unit, and instrumentation and controls. Tests conducted on cold and hot fuels have demonstrated good reproducibility of results.

E. P. Fedorov; L. S. Ianovskii; A. I. Evseev; V. B. Rutovskii; A. N. Kuliapin

1989-01-01

67

Unimolecular reactions of peroxy radicals in atmospheric chemistry and combustion.  

PubMed

Peroxy radicals can undergo isomerisation and dissociation reactions in competition with reactions with NO and with other peroxy radicals. Such a competition is central to the recently proposed mechanism for OH regeneration in the atmospheric oxidation of isoprene. The occurrence of peroxy radical isomerisation reactions in both combustion and atmospheric chemistry is discussed, and exemplified by reference to the peroxy radicals formed from the C(2)H(5), CH(3)CO, HO-C(2)H(2) and HO-C(6)H(6) radicals. The discussion is based on the use of electronic structure and master equation calculations to interpret experimental results. PMID:20815008

Glowacki, David R; Pilling, Michael J

2010-12-17

68

Method and device for determining heats of combustion of gaseous hydrocarbons  

NASA Technical Reports Server (NTRS)

A method and device is provided for a quick, accurate and on-line determination of heats of combustion of gaseous hydrocarbons. First, the amount of oxygen in the carrier air stream is sensed by an oxygen sensing system. Second, three individual volumetric flow rates of oxygen, carrier stream air, and hydrocrabon test gas are introduced into a burner. The hydrocarbon test gas is fed into the burner at a volumetric flow rate, n, measured by a flowmeter. Third, the amount of oxygen in the resulting combustion products is sensed by an oxygen sensing system. Fourth, the volumetric flow rate of oxygen is adjusted until the amount of oxygen in the combustion product equals the amount of oxygen previously sensed in the carrier air stream. This equalizing volumetric flow rate is m and is measured by a flowmeter. The heat of combustion of the hydrocrabon test gas is then determined from the ratio m/n.

Singh, Jag J. (inventor); Sprinkle, Danny R. (inventor); Puster, Richard L. (inventor)

1988-01-01

69

Fireball during combustion of hydrocarbon fuel releases. I. Structure and lift dynamics  

Microsoft Academic Search

The formation, combustion, and thermal interaction of the fireballs which develop upon ignition of a cloud of hydrocarbon\\u000a fuel near the Earths surface are simulated numerically. The axisymmetric nonstationary flow is described by a system of Favre\\u000a averaged conservation equations invoking a (k??)-turbulence model, a model for turbulent combustion, and a global-kinetic scheme for formation and burnup of soot particles.

G. M. Makhviladze; J. P. Roberts; S. E. Yakush

1999-01-01

70

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

Microsoft Academic Search

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

S. Gordon

1982-01-01

71

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

NASA Astrophysics Data System (ADS)

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

Mansurov, Z. A.

2011-01-01

72

Photographic Combustion Characterization of LOX/Hydrocarbon Type Propellants.  

National Technical Information Service (NTIS)

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 (RU...

D. C. Judd

1979-01-01

73

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

NASA Technical Reports Server (NTRS)

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.

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

1986-01-01

74

Method and Device for Determining Heats of Combustion of Gaseous Hydrocarbons.  

National Technical Information Service (NTIS)

A method and device is provided for a quick, accurate and on-line determination of heats of combustion of gaseous hydrocarbons. First, the amount of oxygen in the carrier stream air is sensed by a oxygen sensing system. Second, three individual volumetric...

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

1986-01-01

75

Optical and Chemical Characterization of Carbon Polymorphs Formed During Spray Combustion of Hydrocarbons  

Microsoft Academic Search

The spray combustion of liquid hydrocarbon fuels produces a large variety of structures containing a great number of carbon atoms (carbon polymorphs) which are or may generate toxic pollutants. These carbon polymorphs include compounds with a main aromatic character and larger aggregates as tar and soot.The spectroscopic properties of these polymorphs collected in a spray flame have been investigated by

R. BARBELLA; F. BERETTA; A. CIAJOLO; A. DALESSIO; M. V. PRATI; A. TREGROSS

1990-01-01

76

Applying an Additive Scheme to the Calculation of the Heat of Combustion of Saturated Hydrocarbons  

Microsoft Academic Search

+ + 1.5n + 0.5 () O2 n CO 2 n 1 + () H 2 O Q + + are basic physicochemical quantities used in thermo- chemical calculations and in the optimization of fuel composition. The heat of combustion has been measured for many, but not all, saturated hydrocarbons (3-10) (Table 1), and the accuracy of some of those

E. V. Sagadeev; R. A. Kafiatullin; V. V. Sagadeev; V. I. Sagadeev

2003-01-01

77

Chemical kinetics of hydrocarbon ignition in practical combustion systems  

Microsoft Academic Search

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

Charles K. Westbrook

2000-01-01

78

Calculated Adiabatic Combustion Temperatures of Hydrocarbon-Air Mixtures.  

National Technical Information Service (NTIS)

Manually calculated values of adiabatic combustion temperature are presented, using a slightly modified version of Penner's method, for the simple cases of nondissociation, and of dissociation to CO, H2 and O2 only, for a wide range of gaseous-phase hydro...

E. M. Goodger

1974-01-01

79

New Method for Determining Heats of Combustion of Gaseous Hydrocarbons.  

National Technical Information Service (NTIS)

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 ...

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

1985-01-01

80

Combustion characteristics of hydrogenhydrocarbon hybrid fuels  

Microsoft Academic Search

A comparative study of the flame structure and characteristics of diffusion flames of the mixture of hydrogenhydrocarbon (natural gas and propane) hybrid fuel in a slow co-flowing stream of air is presented. The volumetric content of natural gas and propane in the mixture was varied from 035%. The burner exit Reynolds number was varied from 1503000. Measurements include flame length,

Ahsan R Choudhuri; S. R Gollahalli

2000-01-01

81

A mixing controlled direct chemistry (MCDC) model for diesel engine combustion modelling using large eddy simulation  

Microsoft Academic Search

A mixing controlled direct chemistry (MCDC) combustion model with sub-grid scale (SGS) mixing effects and chemical kinetics has been evaluated for Large Eddy Simulation (LES) of diesel engine combustion. The mixing effect is modelled by a mixing timescale based on mixture fraction variance and sub-grid scalar dissipation rate. The SGS scalar dissipation rate is modelled using a similarity term and

Yuxin Zhang; Christopher J. Rutland

2011-01-01

82

A mixing controlled direct chemistry (MCDC) model for diesel engine combustion modelling using large eddy simulation  

Microsoft Academic Search

A mixing controlled direct chemistry (MCDC) combustion model with sub-grid scale (SGS) mixing effects and chemical kinetics has been evaluated for Large Eddy Simulation (LES) of diesel engine combustion. The mixing effect is modelled by a mixing timescale based on mixture fraction variance and sub-grid scalar dissipation rate. The SGS scalar dissipation rate is modelled using a similarity term and

Yuxin Zhang; Christopher J. Rutland

2012-01-01

83

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

NASA Technical Reports Server (NTRS)

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.

Wey, Thomas Changju; Liu, Nan-suey

2011-01-01

84

Photographic Combustion Characterization of LOX/Hydrocarbon Type Propellants  

NASA Technical Reports Server (NTRS)

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.

Judd, D. C.

1980-01-01

85

Photographic combustion characterization of LOX/Hydrocarbon type propellants  

NASA Technical Reports Server (NTRS)

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.

Judd, D. C.

1980-01-01

86

Ammonia chemistry in oxy-fuel combustion of methane  

SciTech Connect

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

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

2009-10-15

87

New method for determining heats of combustion of gaseous hydrocarbons  

Microsoft Academic Search

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

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

1985-01-01

88

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

PubMed

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

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

2009-03-17

89

Bonding and Chemistry of Hydrocarbon Monolayers on Metal Surfaces.  

National Technical Information Service (NTIS)

Results from ultra-high vacuum surface analysis techniques over the last ten years have dramatically increased our understanding of how unsaturated hydrocarbons react with metal surfaces. We review what has been learned, utilizing results from our laborat...

B. E. Bent G. A. Somorjai

1988-01-01

90

Modeling the unsteady combustion of solid propellants with detailed chemistry  

Microsoft Academic Search

Unsteady combustion phenomena are of great interest to the solid propellant community and have been studied for many years. One area of particular interest is the relation between fluctuating pressure and propellant combustion. Pressure fluctuations, such as acoustics, naturally occur inside solid rocket combustion chambers during motor firing. Coupling between these pressure waves and the burning propellant can lead to

William W. Erikson

1999-01-01

91

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

Microsoft Academic Search

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

Chunshan Song; Xiaoliang Ma

2004-01-01

92

Supersonic combustion performance of hydrogen/hydrocarbon mixtures as determined by a nonintrusive temperature monitor  

NASA Technical Reports Server (NTRS)

A simple and reliable OH absorption technique was developed and applied to measure path integrated temperature and OH number density in scramjet combustor hardware. The first series of measurements was made in premixed combustion products at the exit of a Mach 2 nozzle mounted on a hydrogen fueled vitiated heater. The second series of tests was conducted during supersonic combustion evaluation of hydrogen/hydrocarbon fuel mixtures. These measurements were made near the exit of a 48-inch long diverging supersonic combustor. The OH number density measurements indicated that both the nozzle and the combustor flow were not in equilibrium.

Northam, G. Burton; Lempert, Walter R.; Diskin, Glenn S.; Gregory, Ray W.; Bell, Randy A.

1988-01-01

93

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

NASA Technical Reports Server (NTRS)

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.

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

1991-01-01

94

Photographic combustion characterization of LOX/hydrocarbon type propellants  

NASA Technical Reports Server (NTRS)

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.

Judd, D. C.

1979-01-01

95

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)

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.

Gordon, S.

1982-01-01

96

Combustion generated instabilities in a hydrocarbon-air planar mixing layer  

Microsoft Academic Search

The effects of combustion with high heat release on the initial instabilities of a mixing layer were investigated experimentally in a two-stream planar mixing layer with hydrocarbon fuels. Experiments were performed with non-premixed reactants under two distinct conditions where the lean reactant (air) was placed in either the high-speed (AHS) or low-speed stream (FHS) such that the location of heat

Lyle M. Pickett; Jaal B. Ghandhi

2002-01-01

97

Combustion of two-phase hydrocarbon fuel clouds released into the atmosphere  

Microsoft Academic Search

Numerical modeling of the evolution, behavior, and combustion of two-phase hydrocarbon clouds released into the open atmosphere is presented. A Eulerian-Lagrangian model for transient flows of fuel vapordroplet mixtures is formulated taking into account heat, mass, and momentum exchange between the gaseous and dispersed phases, soot formation, and radiative heat transfer. The calculations are performed for releases of pressure-liquefied propane;

G. M. Makhviladze; J. P. Roberts; S. E. Yakush

1999-01-01

98

Chemical kinetic models for combustion of hydrocarbons and formation of nitric oxide  

NASA Technical Reports Server (NTRS)

The formation of nitrogen oxides NOx during combustion of methane, propane, and a jet fuel, JP-4, was investigated in a jet stirred combustor. The results of the experiments were interpreted using reaction models in which the nitric oxide (NO) forming reactions were coupled to the appropriate hydrocarbon combustion reaction mechanisms. Comparison between the experimental data and the model predictions reveals that the CH + N2 reaction process has a significant effect on NO formation especially in stoichiometric and fuel rich mixtures. Reaction models were assembled that predicted nitric oxide levels that were in reasonable agreement with the jet stirred combustor data and with data obtained from a high pressure (5.9 atm (0.6 MPa)), prevaporized, premixed, flame tube type combustor. The results also suggested that the behavior of hydrocarbon mixtures, like JP-4, may not be significantly different from that of pure hydrocarbons. Application of the propane combustion and nitric oxide formation model to the analysis of NOx emission data reported for various aircraft gas turbines showed the contribution of the various nitric oxide forming processes to the total NOx formed.

Jachimowski, C. J.; Wilson, C. H.

1980-01-01

99

Numerical approaches to combustion modeling. Progress in Astronautics and Aeronautics. Vol. 135  

Microsoft Academic Search

Various papers on numerical approaches to combustion modeling are presented. The topics addressed include; ab initio quantum chemistry for combustion; rate coefficient calculations for combustion modeling; numerical modeling of combustion of complex hydrocarbons; combustion kinetics and sensitivity analysis computations; reduction of chemical reaction models; length scales in laminar and turbulent flames; numerical modeling of laminar diffusion flames; laminar flames in

E. S. Oran; J. P. Boris

1991-01-01

100

Kinetics of 'blue' flames in the gas-phase oxidation and combustion of hydrocarbons and their derivatives  

Microsoft Academic Search

Experimental and calculated data on the kinetics of 'blue' flame observed in the gas-phase oxidation and combustion of hydrocarbons and their derivatives are considered. It is shown that blue flames arise due to the decomposition of hydrogen peroxide that forms in the oxidation of hydrocarbons. They manifest themselves by light emission, are identified by partial heat release (the appearance of

Valentin Ya Basevich; Sergei M. Frolov

2007-01-01

101

Kinetics of ?blue' flames in the gas-phase oxidation and combustion of hydrocarbons and their derivatives  

Microsoft Academic Search

Experimental and calculated data on the kinetics of ?blue' flame observed in the gas-phase oxidation and combustion of hydrocarbons and their derivatives are considered. It is shown that blue flames arise due to the decomposition of hydrogen peroxide that forms in the oxidation of hydrocarbons. They manifest themselves by light emission, are identified by partial heat release (the appearance of

Valentin Ya Basevich; Sergei M Frolov

2007-01-01

102

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

SciTech Connect

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

Miller, R.S.

1986-07-03

103

Effects of aqueous chemistry on the binding of polycyclic aromatic hydrocarbons by dissolved humic materials  

Microsoft Academic Search

The influence of solution chemistry on the binding of three polycyclic aromatic hydrocarbons (PAHs) by well-characterized humic material (Suwannee River humic and fulvic acid) was examined by using fluorescence quenching techniques. The experiments show that binding is complete within 3 min and that the fluorescence of PAH compounds associated with the humic substances is fully quenched as evidenced by quantum

Mark A. Schlautman; James J. Morgan

1993-01-01

104

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

ERIC Educational Resources Information Center

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.

Inner London Education Authority (England).

105

Hydrocarbon-fuel/combustion-chamber-liner materials compatibility  

NASA Technical Reports Server (NTRS)

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.

Homer, G. David

1991-01-01

106

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

SciTech Connect

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

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

2012-06-15

107

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

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

108

Chemical Kinetic Data Base for Combustion Chemistry. Part 2. Methanol  

Microsoft Academic Search

This publication contains evaluated and estimated data on the kinetics of reactions involving methanol and hydroxymethyl radicals and various small inorganic and organic species which are of importance for the proper understanding of methanol combustion and pyrolysis. It is meant to be used in conjunction with the kinetic data given in an earlier publication pertaining to methane pyrolysis and combustion,

Wing Tsang

1987-01-01

109

Characteristics and combustion of future hydrocarbon fuels. [aircraft fuels  

NASA Technical Reports Server (NTRS)

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.

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

1978-01-01

110

Peculiarities of the slow combustion of a hydrocarbon in a wall-less reactor ith laser heating  

Microsoft Academic Search

The slow combustion of the simplest hydrocarbons in a wall-less reactor with laser heating has been studied. In such a reactor, combustion proceeds in the laser beam, while the reactor's wall is at room temperature and does not take part in the process. It has been shown that conversion of propane plus oxygen mixtures can be observed at temperatures above

A. A. Mantashyan

1998-01-01

111

Peculiarities of the slow combustion of a hydrocarbon in a ``wall-less`` reactor with laser heating  

Microsoft Academic Search

The slow combustion of the simplest hydrocarbons in a wall-less reactor with laser heating has been studied. In such a reactor, combustion proceeds in the laser beam, while the reactor`s wall is at room temperature and does not take part in the process. It has been shown that conversion of propane plus oxygen mixtures can be observed at temperatures above

Mantashyan

1998-01-01

112

Emission characteristics of dioxins, furans and polycyclic aromatic hydrocarbons during fluidized-bed combustion of sewage sludge  

Microsoft Academic Search

Pre-dried sewage sludge with high sulfur content was combusted in an electrically heated lab-scale fluidized-bed incinerator. The emission characteristics of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polycyclic aromatic hydrocarbons (PAHs) were studied. Coal and calcium oxide (CaO) were added during the sewage sludge combustion tests to optimize combustion conditions and control SO2 emission. The results indicated that the flue

Wenyi DENG; Jianhua YAN; Xiaodong LI; Fei WANG; Yong CHI; Shengyong LU

2009-01-01

113

Chemistry and the Internal Combustion Engine II: Pollution Problems.  

ERIC Educational Resources Information Center

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

Hunt, C. B.

1979-01-01

114

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

NASA Technical Reports Server (NTRS)

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 mature stage.

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

2007-01-01

115

The Activation of Hydrocarbon CH Bonds over Transition Metal Oxide Catalysts: A FTIR Study of Hydrocarbon Catalytic Combustion over MgCr 2O 4  

Microsoft Academic Search

The interaction of light hydrocarbons (methane, ethane, propane, propene, n-butane, isobutane, 1-butene, benzene, and toluene) with the oxidized surface of the spinel MgCr2O4 (an active hydrocarbon combustion catalyst) has been investigated by FTIR spectroscopy in the temperature range 300-773 K. This interaction results in the reduction of the catalyst and the production of oxygen-containing adsorbed species. These species have been

E. Finnocchio; G. Busca; V. Lorenzelli; R. J. Willey

1995-01-01

116

The surface chemistry of chlorinated hydrocarbon lubrication additives  

NASA Astrophysics Data System (ADS)

A model "extreme pressure" lubricant that consists of a dichlorobutane dissolved in a poly-?-olefin has been synthesized. The model lubricant is characterized by measuring the load required to cause seizure between two moving surfaces. This parameter was measured using a pin and V-block apparatus. The seizure load increased by approximately a factor of three compared to the pure hydrocarbon when 2% chlorinated hydrocarbon was added. In addition, it was found that the average size of the particles that were removed during these experiments decreased significantly when the dichlorobutane was present. An analysis of the surface following tribological testing indicates that the ratio of chlorine to carbon at the surface correlates well with the seizure load, and an X-ray photoelectron spectroscopic analysis suggests that the chlorine is present in the form of a halide. These data indicate that the dichlorobutane additive decomposes at the surface to form a chloride and that this halide formation in some way both increases the load that is required for the contacting surfaces to seize and causes the sizes of the particles that are removed to decrease.

Kotvis, P. V.; Tysoe, W. T.

1989-12-01

117

An adaptive multi-grid chemistry (AMC) model for efficient simulation of HCCI and DI engine combustion  

Microsoft Academic Search

There is a need to reduce the computational expense of practical multidimensional combustion simulations. Simulation of Homogeneous Charge Compression Ignition (HCCI) engine processes requires consideration of detailed chemistry in order to capture the ignition and combustion characteristics. Even with relatively coarse numerical meshes and reduced chemistry mechanisms, calculation times are still unacceptably long. For the simulation of Direct Injection (DI)

Yu Shi; Randy P. Hessel; Rolf D. Reitz

2009-01-01

118

Systematic Reduction of Combustion Reaction Mechanisms of common Hydrocarbons and Oxygenated Fuels  

NASA Astrophysics Data System (ADS)

The aim of this work is the development of a numerical technique for the reduction of reaction mechanisms of common hydrocarbon and oxygenated fuels, such as methane, ethylene, propane, methanol and ethanol, using steady-state and partial equilibrium assumptions. Numerical tests are carried to establish the basic chain for each fuel as well as to determine the amount of small products of combustion, whose concentration depends on the turbulent mixing and needs to be controlled due to environmental restrictions. The results are in agreement with data in the literature.

de Bortoli, A. L.; Vaz, F. A.; Lorenzzetti, G. S.; Martins, I.

2010-09-01

119

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...

120

Combustion Chamber Fluid Dynamics and Hypergolic Gel Propellant Chemistry Simulations for Selectable Thrust Rocket Engines  

Microsoft Academic Search

This paper describes the application of high performance computing to accelerate the development of hypergolic propulsion systems for tactical missiles. Computational fluid dynamics is employed to model the chemically reacting flow within a systempsilas combustion chamber, and computational chemistry is employed to characterize propellant physical and reactive properties. Accomplishments from the past year are presented and discussed.

Michael J. Nusca; Chiung-Chu Chen; Michael J. McQuaid

2008-01-01

121

Combustion Chamber Fluid Dynamics and Hypergolic Gel Propellant Chemistry Simulations for Selectable Thrust Rocket Engines  

Microsoft Academic Search

This paper describes the application of high performance computing to accelerate the development of hypergolic propulsion systems for tactical missiles. Computational fluid dynamics is employed to model the chemically reacting flow within a system's combustion chamber, and computational chemistry is employed to characterize propellant physical and reactive properties. Accomplishments from the past year are presented and discussed.

Michael J. Nusca; Chiung-Chu Chen; Michael J. McQuaid

2007-01-01

122

Combustion Chamber Fluid Dynamics and Hypergolic Gel Propellant Chemistry Simulations for Selectable Thrust Rocket Engines  

Microsoft Academic Search

This paper describes the development and application of high performance computing for the acceleration of tactical missile hypergolic propulsion system development. Computational fluid dynamics is employed to model the chemically reacting flow within a system's combustion chamber, and computational chemistry is employed to characterize propellant physical and reactive properties. Accomplishments from the past year are presented and discussed

Michael J. Nusca; Michael J. McQuaid

2006-01-01

123

Combustion Chamber Fluid Dynamics and Hypergolic Gel Propellant Chemistry Simulations for Selectable Thrust Rocket Engines  

Microsoft Academic Search

This paper describes the development and application of high performance computing for the acceleration of tactical missile hypergolic propulsion system development. Computational fluid dynamics (CFD) is employed to model the chemically reacting flow within a system?s combustion chamber, and computational chemistry is employed to characterize propellant physical and reactive properties. Accomplishments from the past year are presented and discussed.

Michael J. Nusca; Michael J. McQuaid

2005-01-01

124

Combustion Chamber Fluid Dynamics and Hypergolic Gel Propellant Chemistry Simulations for Selectable Thrust Rocket Engines  

Microsoft Academic Search

Challenge Project C2N is dedicated to developing and applying high performance computing capabilities to accelerate the development of hypergolic and hybrid rocket engine concepts. Computational fluid dynamics is employed to model chemically reacting flows within engine combustion chambers and computational chemistry is employed to characterize propellant physical and reactive properties. Accomplishments are presented and discussed.

Chiung-Chu Chen; Michael J. Nusca; Anthony J. Kotlar; Michael J. McQuaid

2009-01-01

125

Global simulation of tropospheric O 3 NO x -hydrocarbon chemistry 1. Model formulation  

Microsoft Academic Search

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

Yuhang Wang; Daniel J. Jacob; Jennifer A. Logan

1998-01-01

126

Chemistry and combustion of fit-for-purpose biofuels.  

PubMed

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

Rothamer, David A; Donohue, Timothy J

2013-06-01

127

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

128

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

PubMed

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

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

2013-04-01

129

The effects of detailed chemistry and transport on microgravity droplet combustion  

NASA Technical Reports Server (NTRS)

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.

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

1995-01-01

130

Emission of oxygenated polycyclic aromatic hydrocarbons from indoor solid fuel combustion.  

PubMed

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 (EF(OPAH)) 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 EF(OPAH) 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 EF(OPAH) 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, R(o), 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 R(o) values were 0.16-0.89 for crop residues and 0.03-0.25 for coals. R(o) 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 ?m for crop residues and high caking coals and <0.7 ?m for the tested low caking briquettes. PMID:21375317

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

2011-04-15

131

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

PubMed

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

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

2013-11-25

132

Fuel Chemistry And Combustion Distribution Effects On Rocket Engine Combustion Stability.  

National Technical Information Service (NTIS)

The goal of the project was to understand how changes in the rate of energy addition can be used to alter the combustion instability characteristics of liquid rocket engines. Fuels with increased energy, either due to higher heats of formation or energeti...

S. D. Heister S. S. Son W. E. Anderson

2013-01-01

133

Method and system for combusting hydrocarbon fuels with low pollutant emissions by controllably extracting heat from the catalytic oxidation stage  

Microsoft Academic Search

A method is described of combusting hydrocarbon fuel, comprising: (a) mixing the fuel with a first air stream to form a fuel\\/air mixture having an equivalence ratio greater than 1; (b) partially oxidizing the fuel by contacting the fuel\\/air mixture with an oxidation catalyst in a catalytic oxidation stage, thereby generating a heat of reaction and a partial oxidation product

M. B. Colket; A. S. Kesten; J. J. Sangiovanni; M. F. Zabielski; D. R. Pandy; D. J. Seery

1993-01-01

134

On the Radiolysis of Ethylene Ices by Energetic Electrons and Implications to the Extraterrestrial Hydrocarbon Chemistry  

NASA Astrophysics Data System (ADS)

The chemical processing of ethylene ices (C2H4) 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 (CH4), the C2 species acetylene (C2H2), ethane (C2H6), the ethyl radical (C2H5), andfor the very first time in ethylene irradiation experimentsthe C4 hydrocarbons 1-butene (C4H8) and n-butane (C4H10). 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.

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

2014-07-01

135

The effect of microwave and pulse corona discharges on hydrocarbons partial oxidation, combustion and detonation initiation  

NASA Astrophysics Data System (ADS)

We present experimental and theoretical results on application of microwave plasmas for stimulation of partial oxidation processes for hydrogen rich gas production from gas and liquid hydrocarbons. Said results ranging from investigation of plasma catalysis mechanism, kinetics and energy balance to plasma reactor design and heat management issues. It is appeared that relatively small plasma energy deposition (0.1eV per outcome H2, or CO molecule) under certain range of plasma parameters leads to the significant acceleration of partial oxidation processes and this effect can be used for compact on board plasma reformer development. The paper includes test results of 10 st.m3/h plasma reformer. Experimental and theoretical results devoted to MW plasma and pulse corona discharge application for combustion and detonation initiation are discussed as well.

Babaritskii, Alexander; Deminsky, Maxim; Jivotov, Viktor; Medvedev, Dmitrii; Korobtsev, Sergey; Smirnov, Roman; Konovalov, Grigory; Krotov, Mikhail; Strelkova, Marina; Potapkin, Boris

2006-10-01

136

Investigation and Optimization of Biodiesel Chemistry for HCCI Combustion  

SciTech Connect

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

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

2011-01-01

137

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

PubMed

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

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

2012-08-01

138

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

NASA Technical Reports Server (NTRS)

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.

Gordon, S.

1982-01-01

139

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

PubMed

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

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

140

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

SciTech Connect

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

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

2009-04-15

141

Small-Scale Abundance Variations in TMC-1: Dynamics and Hydrocarbon Chemistry  

NASA Astrophysics Data System (ADS)

We present high spectral resolution observations of eighteen molecules, including high-quality maps of CCS and HC7N in TMC-1, using NASA's Deep Space Network 70 m antenna to study the interaction between cloud dynamics and chemistry. Other molecules shown in our study are C18O, NH3, CS, C3S, C3H2, H2C3, H2C4, H2C6, HC3N, HC5N, DC5N, HC9N, C4H, C5H, C6H, and a successful detection of the rare C8H molecule. In addition, we have searched for and set meaningful abundance limits on several carbon chain and ring molecules such as C7H, H2C5, c-H2C5, and biogenic molecules such as pyrrole and glycine. All the species observed in TMC-1 show large spectral-line variations in both intensity and shape over extremely small scales (~0.03 pc). Maps of CCS and HC7N display abundance ratio variations of 3-5 along individual lines of sight. The high degree of clumpiness, transient nature of clumps, and gas-phase enrichment adequately explain the ``early-time'' chemistry and the molecular complexity in TMC-1. This enrichment has interesting implications for hydrocarbon chemistry in TMC-1, and presumably other clumpy, dark clouds. Specifically, the large number of clumps at various stages of early-time chemical evolution increases the chances for detection of complex hydrocarbons, since the probability of observing a clump at the time of peak abundance for a given molecular species is increased. We suggest two mechanisms for explaining the small-scale variations: (1) the passage of MHD waves in a clumpy medium and (2) grain impacts during clump-clump collisions. In the quiescent region far from any protostar, the MHD activity can be generated locally by clump collisions. The passage of MHD waves helps maintain early-time chemistry in the clumps. Both mechanisms provide enough energy to raise grain temperatures from 10 K to Tcrit~30 K, sufficient to cause reactive radical explosions in grain mantles and thermal desorption. In this manner, the mantle injection causes TMC-1 to exhibit some aspects of ``hot-core'' chemistry, as seen in more massive star-forming regions. The transient nature of the clumps and the mantle-driven chemistry make TMC-1 a good target for future searches of complex molecular species.

Dickens, J. E.; Langer, W. D.; Velusamy, T.

2001-09-01

142

Emission of polycyclic aromatic hydrocarbons from coal and sewage sludge co-combustion in a drop tube furnace.  

PubMed

The emission characteristics of polycyclic aromatic hydrocarbons (PAHs) during coal and sewage sludge co-combustion were investigated in a laboratory-scale drop tube furnace. The experimental results demonstrated that coal and sewage sludge co-combustion was beneficial in reducing PAH emissions and PAH toxic equivalent (TEQ) concentrations. Meanwhile, the five-ring PAHs were the main contributor in reducing the concentration of PAHs and TEQ. Moreover, the two- and five-ring PAH concentrations decreased as the mass fraction of sewage sludge in the mixture increased from 0% to 100%. It was also found that PAHs from coal mono-combustion was dominated by the four- and five-ring PAHs. As for the sewage sludge mono-combustion, the three- and four-ring PAHs were the principal components. PMID:22751851

Han, Jun; Qin, Linbo; Ye, Wei; Li, Yuqi; Liu, Long; Wang, Hao; Yao, Hong

2012-09-01

143

Kinetics of 'blue' flames in the gas-phase oxidation and combustion of hydrocarbons and their derivatives  

NASA Astrophysics Data System (ADS)

Experimental and calculated data on the kinetics of 'blue' flame observed in the gas-phase oxidation and combustion of hydrocarbons and their derivatives are considered. It is shown that blue flames arise due to the decomposition of hydrogen peroxide that forms in the oxidation of hydrocarbons. They manifest themselves by light emission, are identified by partial heat release (the appearance of a step in the time dependences of temperature and pressure observed in closed-vessel experiments) and propagate as conventional hot flames.

Basevich, Valentin Ya; Frolov, Sergei M.

2007-09-01

144

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

PubMed

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

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

2011-03-15

145

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

NASA Astrophysics Data System (ADS)

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.

Valle-Hernndez, B. L.; Amador-Muoz, O.; Jazcilevich, A. D.; Santos-Medina, G. L.; Hernndez-Lopz, E.; Villalobos-Pietrini, R.

2013-05-01

146

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

Microsoft Academic Search

Combustion of H\\/hydrocarbon (HC) fuel mixtures may be considered in certain volume-limited supersonic airbreathing propulsion applications. Effects of HC addition to H 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 (N and\\/or HC)-diluted H mixture opposed

G. L. Pellett; R. Guerra; L. G. Wilson; R. N. Reeves; G. B. Northam

1987-01-01

147

The Identification of Cyclopenta-Fused and Ethynyl-Substituted Polycyclic Aromatic Hydrocarbons in Benzene Droplet Combustion Products  

Microsoft Academic Search

In order to investigate new aspects of polycyclic aromatic hydrocarbon (PAH) growth and soot formation, we have synthesized special reference standards of cyclopenta-fused PAH (CP-PAH) and ethynyl-substituted PAH. We have identified several of these CP-PAH and ethynyl-PAH in benzene droplet combustion products, using high pressure liquid chromatography (HPLC) and ultraviolet-visible (UV) absorption spectroscopy. Although one CP-PAH identified in these products

Nathan D. Marsh; Mary J. Wornat; Lawrence T. Scott; Atena Necula; Arthur L. Lafleur; Elaine F. Plummer

2000-01-01

148

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

NASA Technical Reports Server (NTRS)

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.

Michel, R. W.

1983-01-01

149

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

NASA Technical Reports Server (NTRS)

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.

Makel, Darby B.; Rosenberg, Sanders D.

1990-01-01

150

Numerical investigation of a helicopter combustion chamber using LES and tabulated chemistry  

NASA Astrophysics Data System (ADS)

This article presents Large Eddy Simulations (LES) of a realistic aeronautical combustor device: the chamber CTA1 designed by TURBOMECA. Under nominal operating conditions, experiments show hot spots observed on the combustor walls, in the vicinity of the injectors. These high temperature regions disappear when modifying the fuel stream equivalence ratio. In order to account for detailed chemistry effects within LES, the numerical simulation uses the recently developed turbulent combustion model F-TACLES (Filtered TAbulated Chemistry for LES). The principle of this model is first to generate a lookup table where thermochemical variables are computed from a set of filtered laminar unstrained premixed flamelets. To model the interactions between the flame and the turbulence at the subgrid scale, a flame wrinkling analytical model is introduced and the Filtered Density Function (FDF) of the mixture fraction is modeled by a ? function. Filtered thermochemical quantities are stored as a function of three coordinates: the filtered progress variable, the filtered mixture fraction and the mixture fraction subgrid scale variance. The chemical lookup table is then coupled with the LES using a mathematical formalism that ensures an accurate prediction of the flame dynamics. The numerical simulation of the CTA1 chamber with the F-TACLES turbulent combustion model reproduces fairly the temperature fields observed in experiments. In particular the influence of the fuel stream equivalence ratio on the flame position is well captured.

Auzillon, Pierre; Riber, Elonore; Gicquel, Laurent Y. M.; Gicquel, Olivier; Darabiha, Nasser; Veynante, Denis; Fiorina, Benot

2013-01-01

151

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

NASA Technical Reports Server (NTRS)

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.

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

1955-01-01

152

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

Microsoft Academic Search

We present a description and evaluation of LMDz-INCA, a global three-dimensional chemistry-climate model, pertaining to its recently developed NMHC version. In this substantially extended version of the model a comprehensive representation of the photochemistry of non-methane hydrocarbons (NMHC) and volatile organic compounds (VOC) from biogenic, anthropogenic, and biomass-burning sources has been included. The tropospheric annual mean methane (9.2 years) and

G. A. Folberth; D. A. Hauglustaine; J. Lathire; F. Brocheton

2006-01-01

153

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

NASA Technical Reports Server (NTRS)

A sound data base was established by analytically and experimentally generating basic regenerative cooling, combustion performance, combustion stability, and combustion chamber heat transfer parameters for LOX/HC propellants, with specific application to second generation orbit maneuvering and reaction control systems (OMS/RCS) for the Space Shuttle Orbiter.

Gross, R. S.

1980-01-01

154

Method for automatically initiating in situ combustion for enhanced thermal recovery of hydrocarbons from a well  

Microsoft Academic Search

A method for initiating an in situ combustion operation for heating a well to recover petroleum from a subterranean reservoir in the well comprises lowering an elongated combustion chamber suspended from a hollow electrical cable with an air supply tube therearound which supplies electricity, fuel gas, and air to the combusion chamber, mixing an air-fuel mixture in the combustion chamber,

C. E. Howard; D. G. Calvin; R. W. Jr. Pitts

1979-01-01

155

Photochemistry of Saturn's Atmosphere. I. Hydrocarbon Chemistry and Comparisons with ISO Observations  

NASA Astrophysics Data System (ADS)

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 densities of CH 3, CH 3C 2H, and C 4H 2 above 10 mbar are 4 +2-1.510 13 cm -2, (1.10.3)10 15 cm -2, and (1.20.3)10 14 cm -2, respectively. The observed ISO emission features also indicate C 2H 2 mixing ratios of 1.2 +0.9-0.610 -6 at 0.3 mbar and (2.70.8)10 -7 at 1.4 mbar, and a C 2H 6 mixing ratio of (92.5)10 -6 at 0.5 mbar. Upper limits are provided for C 2H 4, CH 2CCH 2, C 3H 8, and C 6H 2. The sensitivity of the model results to variations in the eddy diffusion coefficient profile, the solar flux, the CH 4 photolysis branching ratios, the atomic hydrogen influx, and key reaction rates are discussed in detail. We find that C 4H 2 and CH 3C 2H are particularly good tracers of important chemical processes and physical conditions in Saturn's upper atmosphere, and C 2H 6 is a good tracer of the eddy diffusion coefficient in Saturn's lower stratosphere. The eddy diffusion coefficient must be smaller than 310 4 cm 2 s -1 at pressures greater than 1 mbar in order to reproduce the C 2H 6 abundance inferred from ISO observations. The eddy diffusion coefficients in the upper stratosphere could be constrained by observations of CH 3 radicals if the low-temperature chemistry of CH 3 were better understood. We also discuss the implications of our modeling for aerosol formation in Saturn's lower stratospherediacetylene, butane, and water condense between 1 and 300 mbar in our model and will dominate stratospheric haze formation at nonauroral latitudes. Our photochemical models will be useful for planning observational sequences and for analyzing data from the upcoming Cassini mission.

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

2000-02-01

156

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

Microsoft Academic Search

The eightieth anniversary of Academician, Lenin Prize Winner Rem Ivanovich Soloukhin is an important event for the scientific\\u000a association of investigators of combustion and detonation processes. R. I. Soloukhin has developed original gasdynamic laser\\u000a systems based on the selective thermal excitation and mixing in a supersonic flow: efficient high-power gas-flow lasers of\\u000a convective type with electric excitation and chemical lasers

Z. A. Mansurov

2011-01-01

157

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

PubMed Central

Coal consumption is one important contributor to energy production, and is regarded as one of the most important sources of air pollutants that have considerable impacts on human health and climate change. Emissions of polycyclic aromatic hydrocarbons (PAHs) from coal combustion were studied in a typical stove. Emission factors (EFs) of 16 EPA priority PAHs from tested coals ranged from 6.25 1.16 mg kg?1 (anthracite) to 253 170 mg kg?1 (bituminous), with NAP and PHE dominated in gaseous and particulate phases, respectively. Size distributions of particulate phase PAHs from tested coals showed that they were mostly associated with particulate matter (PM) with size either between 0.7 and 2.1 ?m or less than 0.4 ?m (PM0.4). In the latter category, not only were more PAHs present in PM0.4, but also contained higher fractions of high molecular weight PAHs. Generally, there were more than 89% of total particulate phase PAHs associated with PM2.5. Gas-particle partitioning of freshly emitted PAHs from residential coal combustions were thought to be mainly controlled by absorption rather than adsorption, which is similar to those from other sources. Besides, the influence of fuel properties and combustion conditions was further investigated by using stepwise regression analysis, which indicated that almost 57 10% of total variations in PAH EFs can be accounted for by moisture and volatile matter content of coal in residential combustion.

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

2013-01-01

158

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

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.

Hower, J.C.; Robertson, J.D.; Elswick, E.R.; Roberts, J.M.; Brandsteder, K.; Trimble, A.S.; Mardon, S.M. [University of Kentucky, Lexington, KY (United States). Center for Applied Energy Research

2007-07-01

159

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

NASA Technical Reports Server (NTRS)

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.

Schoenman, L.

1983-01-01

160

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

Microsoft Academic Search

In this work, a direct thermal desorption\\/gas chromatography\\/mass spectrometry (TD\\/GC\\/MS) method is implemented to determine the polycyclic aromatic hydrocarbon (PAH) composition (MW=202302amu) in size-segregated aerosols from residential wood combustion. Six combustion tests are performed with two commonly burned wood fuel species, Douglas-fir (Pseudotsuga sp.) and white oak (Quercus sp.). Atmospheric dilution and cooling of the aerosol plume are simulated in

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

2003-01-01

161

Bacterial and human cell mutagenicity study of some C[sub 18]H[sub 10] cyclopenta-fused polycyclic aromatic hydrocarbons associated with fossil fuels combustion  

Microsoft Academic Search

A number of isomeric C[sub 18]H[sub 10] 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 C[sub 18]H[sub 10] CP-PAHs: benzol

A. L. Lafleur; J. P. Longwell; J. A. Marr; P. A. Monchamp; W. G. Thilly; P. P. Y. Mulder; B. B. Boere; J. Cornelisse; J. Lugtenburg

1993-01-01

162

Effects of aqueous chemistry on the binding of polycyclic aromatic hydrocarbons by dissolved humic materials  

SciTech Connect

The influence of solution chemistry on the binding of three polycyclic aromatic hydrocarbons (PAHs) by well-characterized humic material (Suwannee River humic and fulvic acid) was examined by using fluorescence quenching techniques. The experiments show that binding is complete within 3 min and that the fluorescence of PAH compounds associated with the humic substances is fully quenched as evidenced by quantum yields which approached zero for all systems. These observations validate the use of fluorescence quenching in determining partition coefficients. In NaCl solutions, the binding of PAHs by Suwannee River humic material generally decreased with increases in pH (constant ionic strength) and generally decreased with increasing ionic strength (fixed pH). The presence of Ca[sup 2+] yielded mixed results: at neutral to high pH values, it generally increased the binding of PAHs relative to that in NaCl solutions, while at low pH it generally had little effect on the binding. From the results of this study, it is hypothesized that the binding of a particular PAH compound by Suwannee River humic substances depends not only on the hydrophobicity of the PAH solute but also on the size of the solute molecule and its ability to fit into hydrophobic cavities in humic and fulvic material. This hypothesis is supported by the experimental observations above, as well as the failure of a Flory-Huggins partitioning (i.e., dissolution) model to consistently characterize the hydrophobic environment of the humic substances. 47 refs., 6 figs., 3 tabs.

Schlautman, M.A.; Morgan, J.J. (California Inst. of Technology, Pasadena (United States))

1993-05-01

163

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

NASA Technical Reports Server (NTRS)

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 better understood. We also discuss the implications of our modeling for aerosol formation in Saturn's lower stratosphere-diacetylene, butane, and water condense between approximately 1 and 300 mbar in our model and will dominate stratospheric haze formation at nonauroral latitudes. Our photochemical models will be useful for planning observational sequences and for analyzing data from the upcoming Cassini mission.

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

2000-01-01

164

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

SciTech Connect

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.

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

2012-01-01

165

Hydrogen production in ultrarich combustion of hydrocarbon fuels in porous media  

Microsoft Academic Search

Rich and ultrarich combustion of methane, ethane, and propane inside inert porous media is studied experimentally and numerically to examine the suitability of the concept for hydrogen production. Temperature, velocities, and chemical products of the combustion waves were recorded experimentally at a range of equivalence ratios from stoichiometry (?=1.0) to ?=2.5, for a filtration velocity of 12cm\\/s. Two-temperature numerical model

Mario Toledo; Valeri Bubnovich; Alexei Saveliev; Lawrence Kennedy

2009-01-01

166

The use of dynamic adaptive chemistry in combustion simulation of gasoline surrogate fuels  

SciTech Connect

A computationally efficient dynamic adaptive chemistry (DAC) scheme is described that permits on-the-fly mechanism reduction during reactive flow calculations. The scheme reduces a globally valid full mechanism to a locally, instantaneously applicable smaller mechanism. Previously we demonstrated its applicability to homogeneous charge compression ignition (HCCI) problems with n-heptane [L. Liang, J.G. Stevens, J.T. Farrell, Proc. Combust. Inst. 32 (2009) 527-534]. In this work we demonstrate the broader utility of the DAC scheme through the simulation of HCCI and shock tube ignition delay times (IDT) for three gasoline surrogates, including two- and three-component blends of primary reference fuels (PRF) and toluene reference fuels (TRF). Both a detailed 1099-species mechanism and a skeletal 150-species mechanism are investigated as the full mechanism to explore the impact of fuel complexity on the DAC scheme. For all conditions studied, pressure and key species profiles calculated using the DAC scheme are in excellent agreement with the results obtained using the full mechanisms. For the HCCI calculations using the 1099- and 150-species mechanisms, the DAC scheme achieves 70- and 15-fold CPU time reductions, respectively. For the IDT problems, corresponding speed-up factors of 10 and two are obtained. Practical guidance is provided for choosing the search-initiating species set, selecting the threshold, and implementing the DAC scheme in a computational fluid dynamics (CFD) framework. (author)

Liang, Long; Raman, Sumathy; Farrell, John T. [Corporate Strategic Research Laboratories, ExxonMobil Research and Engineering Company, 1545 Route 22 East, Annandale, NJ 08801 (United States); Stevens, John G. [Corporate Strategic Research Laboratories, ExxonMobil Research and Engineering Company, 1545 Route 22 East, Annandale, NJ 08801 (United States); Department of Mathematical Sciences, Montclair State University, Montclair, NJ 07043 (United States)

2009-07-15

167

Chemistry of internal combustion engine deposits. I. Microanalysis, thermogravimetric analysis, and infrared spectroscopy  

SciTech Connect

The deposits examined in this study were generated by six-cylinder engines employing various unleaded fuel and lube combinations. The entire deposit mass (piston top and head area of all cylinders) was combined; while obvious artifacts such as paint and bristles from brushes were removed, ferromagnetic impurities were not. Elemental analysis was performed by Galbraith Laboratories (Knoxville, TN) using the techniques indicated: carbon and hydrogen (Pragel), nitrogen (Dumas), oxygen (LECO), and inorganics (wet chemistry/atomic absorption). The weight of the sample as a function of time was determined using a Dupont 951 thermogravimetric analyzer interfaced to a Dupont 990 thermal analyzer. Typical sample sizes were 20 mg, and temperatures between ambient and 1000/sup 0/C were recorded with a chromel/alumel thermocouple. Infrared spectra of deposits were run in pellet form (about 1 mg in KBr) on a Digilab FTS-14. The analyses show that combustion chamber deposits are volatile carbonaceous materials, having more in common with bituminous coals than with graphite. A unifying trait among the deposits is the presence of approximately 25 wt % oxygen, which is distributed among a variety of chemical functionalities, including -OH, C=O, and C-O. Chemical titration of these deposits is difficult.

Ebert, L.B.; Davis, W.H. Jr.; Mills, D.R.; Dennerlein, J.D.

1981-03-01

168

Control of combustibility of volatile hydrocarbons and particulate matter in an exhaust gas stream by use of a high velocity burner in a carbon bake ring furnace  

Microsoft Academic Search

The present invention relates to a method of and an apparatus for controlling the combustibility of volatile hydrocarbons and particulate matter in an exhaust gas stream driven off from a carbon product being baked in a furnace. In a prebaking stage, the carbon product is heat treated in a temperature range of 300 to 600° C. In order to drive

F. D. Arnold; C. M. Benton; G. D. Evrad; H. O. Forberg; R. L. Tuscher

1981-01-01

169

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

NASA Technical Reports Server (NTRS)

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.

1985-01-01

170

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

SciTech Connect

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 developed mechanisms and to assess the uncertainties in elementary rate constant evaluations.

Dryer, Frederick L.

2009-04-10

171

Method and apparatus for increasing radiant heat production of hydrocarbon fuel combustion systems  

Microsoft Academic Search

This patent describes a combustion apparatus. It comprises: a pair of spaced electrodes defining a gap; means for conveying an oxidant free fuel through the gap; means for establishing a continuous arc across the gap to pyrolytically form particles dispersed in such conveyed fuel, means for preventing the deposit of such pyrolytically formed particles on one of the electrodes; and

1991-01-01

172

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

PubMed

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/m3 on an annual basis. Although only 2.3% of the area in Tianjin exceeded the national standard of 10 ng/m3, 41% of the entire population lives within this area. PMID:16913110

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

2006-08-01

173

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

SciTech Connect

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.

Shu Tao; Xinrong Li; Yu Yang; Raymond M. Coveney, Jr.; Xiaoxia Lu; Haitao Chen; Weiran Shen [Peking University, Beijing (China). Laboratory for Earth Surface Processes, College of Environmental Sciences

2006-08-01

174

HYDROCARBON AND OXIDANT CHEMISTRY OBSERVED AT A SITE NEAR ST. LOUIS  

EPA Science Inventory

Integrated quantitative gas chromatographic measurements of the nearly one hundred individual hydrocarbons present in ambient air were made to deternime the total non-methane organic burden at a midwest rural site in coordination with halocarbon, oxidant and local meteorological ...

175

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

Microsoft Academic Search

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

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

1996-01-01

176

Explosive model of low-speed combustion of gaseous hydrocarbon-air mixtures  

Microsoft Academic Search

An explosive model is proposed for the calculation of the stationary velocity in mixtures of air and combined fuel consisting\\u000a of various gaseous hydrocarbons. The required equations are obtained from a consideration of the flame-front structure on\\u000a the basis of the thermal diffusion theory. In contrast to known relationships, the proposed model does not contain any ambiguities\\u000a in the equation

U. V. Tunik; G. D. Smekhov

1998-01-01

177

The characterization of polycyclic aromatic hydrocarbons produced in combustion and pyrolysis environments: Laboratory-generated products of model compounds  

NASA Astrophysics Data System (ADS)

Laboratory and computational techniques have been developed to characterize polycyclic aromatic hydrocarbons (PAH), presumed soot precursors and potentially harmful by-products of a variety of pyrolysis and combustion processes. Newly synthesized reference standards and the application of high-pressure liquid chromatography (HPLC) with ultraviolet-visible (UV) absorption spectroscopy have led to the unequivocal identification, among combustion and pyrolysis products, of several new PAH, many of which belong to the two newly recognized PAH classes, ethynyl-PAH and cyclopenta-fused PAH (CP-PAH). Empirical rules have also been formulated for the UV spectra of ethynyl- and CP-PAH; these rules allow preliminary identification of candidate compounds in combustion products, prior to labor-intensive synthetic procedures necessary for identity confirmation. Pyrolysis products have been analyzed in two sets of experiments: benzene droplet combustion and gas-phase catechol (ortho-dihydroxybenzene) pyrolysis. In the first, benzene droplets are ignited and then captured by a phase-discriminating sampling probe; gas-phase pyrolysis products transported into the liquid phase of the droplet are identified and quantified. In the second set of experiments, catechol is pyrolysed in a laminar-flow reactor, at 700--1000C and 0.4--1 sec, producing a range of aromatic products; the 30 most abundant are quantified. Compositional analysis of the pyrolysis products by HPLC reveals a wide variety of PAH which have never before been identified as products of these fuels. In general, most products appear to be the result of multiple ring-buildup steps. The data reported here for catechol products represent one of the most extensive quantifications of aromatic products from any fuel, and the only one for catechol. Semiempirical quantum chemical computations have been performed in order to examine the potential energy surfaces and equilibrium distributions of several compounds. The observed preference for cyclization to CP-PAH over formation of ethynyl-PAH can be explained by the significantly lower energy barrier. Comparison of computed PAH equilibrium distributions to those found experimentally reveals close agreement only for the C16H10 isomers---corroborating previous evidence of a facile route for interconversion of internally and externally fused five-membered rings in this isomer group.

Marsh, Nathan Douglas

178

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

NASA Technical Reports Server (NTRS)

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.

1982-01-01

179

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

SciTech Connect

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

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

1988-05-03

180

Combustion-Derived Hydrocarbons Localize to Lipid Droplets in Respiratory Cells  

Microsoft Academic Search

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

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

181

The effect of surfactant hydrocarbon tail length on the crystallite size of Sr-hexaferrite powders synthesized by a sol gel auto-combustion method  

NASA Astrophysics Data System (ADS)

In this work a novel sol-gel auto-combustion method has been used to synthesize nanocrystalline Sr-hexaferrite powder. The gels were prepared from metal nitrates, citric acid and trimethylamine as a pH-adjusting agent without any surfactant and with various cationic surfactants such as n-decyltrimethylammonium bromide, n-dodecyltrimethylammonium bromide, n-tetradecyltrimethylammonium bromide and n-cetyltrimethylammonium bromide, which are different in hydrocarbonic tail length. Results showed that applying surfactant, particularly with longer hydrocarbonic tail, results in smaller crystallite size and narrower particles size distribution.

Ghobeiti Hasab, M.; Seyyed Ebrahimi, S. A.; Badiei, A.

2007-03-01

182

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

SciTech Connect

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.

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

1981-04-01

183

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

Microsoft Academic Search

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

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

2008-01-01

184

Combustion  

NASA Astrophysics Data System (ADS)

The process whereby a substance is combined with oxygen with the production of heat. Burning is a familiar example of this process. The energy required to propel chemical rockets is provided by the combustion of fuel with an oxidant at very high temperatures. A common oxidant is liquid oxygen (often denoted by LOX). Others include hydrogen peroxide and nitrogen tetroxide....

Murdin, P.

2000-11-01

185

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

Microsoft Academic Search

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

Ingrid Faengmark; Bert van Bavel; Stellan Marklund; C. Rappe; B. Stroemberg; N. Berge

1993-01-01

186

Sorption-enhanced steam reforming of hydrocarbons with autothermal sorbent regeneration in a moving heat wave of a catalytic combustion reaction  

Microsoft Academic Search

A novel technological concept of sorption-enhanced steam reforming of hydrocarbons is suggested. The peculiarity of the concept\\u000a is the autothermal regeneration of the carbon dioxide scavenger in the moving super-adiabatic heat wave of an exothermic catalytic\\u000a combustion reaction performed directly inside the adsorption-catalytic bed. The capability and high efficiency of the proposed\\u000a technological approach are confirmed by process simulation. The

Andrey N. Zagoruiko; Alexey G. Okunev

2007-01-01

187

Effect of in-situ heat treatment on coal char reactivity. Ostwald equations and combustion efficiency in hydrocarbon and coal flames. Progress report  

Microsoft Academic Search

The Ostwald Equations have been in use for about 60 years as a means of cross-checking the accuracy of gas analyses taken in the exhaust of hydrocarbon (CH\\/sub x\\/) or coal (CH\\/sub x\\/O\\/sub y\\/) flames, or along the path of combustion if certain limitations are met. The accuracy of the analyses is important if they are to be used for

Essenhigh

1985-01-01

188

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

PubMed

Voyager 2 found that the Uranian magnetosphere has a substantial flux of energetic charged particles, which becomes rich in higher energies at low magnetospheric L near the orbit of Miranda. The electrons precipitate to produce aurorae, which have been observed in the ultraviolet. The more energetic component of the precipitating electrons can initiate radiation chemistry in the methane-poor stratosphere, near 0.1 mbar where the CH4 mole fraction XCH4 approximately equal to 10(-5). We present laboratory results for cold plasma (glow) discharge in continuous flow H2-He-CH4 atmospheres with mol fractions XCH4 = 10(-2) to 10(-3) and total pressure p = 60 to 0.6 mbar. The yields of simple hydrocarbons in these experiments and an estimate of precipitating electron flux consistent with the Voyager ultraviolet spectroscopy results indicate the globally averaged auroral processing rate of CH4 to higher hydrocarbons approximately equal to 3 x 10(6) C cm-2 s-1, comparable to the globally averaged photochemical production rate. The local rate approximately 2 x 10(8) C cm-2 s-1 in the auroral zones (approximately 20 degrees in diameter) at 15 degrees S and 45 degrees N latitude greatly exceeds the photochemical rate. Even at very low XCH4 approximately equal to 10(-3) the yield (summed over all products) G > approximately 10(-2) C/100 eV and the average slope alpha = > approximately -0.4, where the summation is over all product molecules of a given carbon number eta and the square brackets denote abundance. The yield therefore decreases slowly with molecular complexity: hydrocarbons through C7Hx should be present in auroral zones at abundances > approximately 10(-2) of the simplest C2 hydrocarbons. Saturated hydrocarbons (C2H6, C3H8, C4H10, etc.) are mostly shielded from photodissociation by C2H2 and will therefore persist at the sunlit, as well as the currently dark, magnetic polar regions. PMID:11542129

Thompson, W R; Henry, T; Khare, B N; Flynn, L; Schwartz, J; Sagan, C

1987-12-30

189

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

NASA Astrophysics Data System (ADS)

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 250C 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 values were completely consistent with the abiogenic polymerization model, as for the field samples. It appears that the rapid rate of chain polymerization is such that any net isotopic fractionation associated with subsequent carbon addition steps is negligible and suggests that carbon isotope values for the higher alkane gases may be predicted independent of the fractionation associated with the first step.1.Sherwood Lollar et al. (2002) Nature 416:522-524.2.Sherwood Lollar et al. (2008) GCA doi:10.1016/j.gca.2008.07.004

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

2008-12-01

190

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

NASA Technical Reports Server (NTRS)

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.

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

1987-01-01

191

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

NASA Technical Reports Server (NTRS)

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.

Michel, R. W.

1983-01-01

192

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

NASA Technical Reports Server (NTRS)

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.

Bittker, D. A.; Wolfbrandt, G.

1981-01-01

193

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

PubMed

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

Pisupati; Wasco; Scaroni

2000-05-29

194

Coal Combustion and Utilization.  

National Technical Information Service (NTIS)

Information on the following subjects is included within the scope of the publication, but all subjects may not appear in each issue: coal combustion, power plant fuel, MHD generators, fuel cells, combustion chemistry, combustion systems.

1986-01-01

195

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

PubMed

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

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

2013-08-21

196

Fundamentals of Gas Turbine combustion  

NASA Technical Reports Server (NTRS)

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.

Gerstein, M.

1979-01-01

197

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)

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 aromatic compounds in cold environments, such as on Titan or in the interstellar medium.

Landera, Alexander

198

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

PubMed

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

Welz, Oliver; Zdor, 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

199

Terascale High-Fidelity Simulations of Turbulent Combustion with Detailed Chemistry  

SciTech Connect

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

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

2009-02-02

200

Metal [Fe(II), Cu(I), Co(II), Mn(III)]\\/hydroperoxide-induced activation of dioxygen (O 2) for the ketonization of hydrocarbons: oxygenated Fenton chemistry  

Microsoft Academic Search

Recent reports have established that Fenton chemistry involves the formation of hydroperoxide (ROOH) adducts (1) of reduced transition metals [iron(II), copper(I), and cobalt(II)] via nucleophilic addition {e.g. } (B = py or H2O). These reactive intermediates (1) react with (a) excess catalyst (FeIILx) to form LxFeIIIOH(R); (b) excess ROOH to form O2, H2O and ROH; (c) excess hydrocarbon (RH) to

Donald T. Sawyer

1997-01-01

201

Effects of hydrocarbon addition on cellular instabilities in expanding syngasair spherical premixed flames  

Microsoft Academic Search

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

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

2009-01-01

202

Natural gas combustion chemistry mechanisms rsearch. Annual report, December 1, 1992-December 31, 1993  

SciTech Connect

An evaluated mechanism of elementary rate constants and thermodynamics for methane combustion was developed. The experimental data set and sensitivity computations for the optimization procedure were selected and completed; the optimization calculations were begun. Important kinetics measurements and analysis were made to aid in this endeavor. Shock tube experiments determined CH3 and OH concentrations in CH4-O2-Ar mixtures for the optimization. Quantum calculations were performed for the CH + N2 reaction. Modeling studies examined the development of reduced and skeletal mechanisms and the prediction of NO and soot levels in diesel engines.

Smith, G.P.; Crosley, D.R.; Golden, D.M.; Frenklach, M.; Gardiner, W.C.

1994-09-23

203

Chemical Kinetic Data Base for Combustion Chemistry. Part I. Methane and Related Compounds  

Microsoft Academic Search

This document contains evaluated data on the kinetics and thermodynamic properties of species that are of importance in methane pyrolysis and combustion. Specifically, the substances considered include H, H2, O, O2, OH, HO2, H2O2, H2O, CH4, C2H6, HCHO, CO2, CO, HCO, CH3, C2H5, C2H4, C2H3, C2H2, C2H, CH3CO, CH3O2, CH3O, singlet CH2, and triplet CH2. All possible reactions are considered.

W. Tsang; R. F. Hampson

1986-01-01

204

Chemistry  

NSDL National Science Digital Library

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

K-12 Outreach,

205

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

SciTech Connect

The authors present the results of a numerical study of shock-induced ethylene combustion. They compare the accuracy and efficiency of a variety of methods when applied to this combustion problem. For a full kinetics scheme they consider the speed of a range of alternative ordinary differential equation solvers. They find that for the coupled ODE-hydrodynamic problem an extrapolated linearly implicit Euler method is the fastest of the methods used, but that otherwise a fourth-order Rosenbrock scheme is the fastest solution method. The identity of the fastest method changes because of the start up conditions having to be recalculated at the start of every step in a coupled ODE-hydrodynamics module. The authors then apply a detailed reduction strategy to a chemical kinetics reaction data set and find that it cannot be reduced by many reactions as it is already a fairly compact set. They then introduce an induction parameter model based on the two parameter model of Taki and Fujiwara and the work of Oran et al. They derive functions that model the induction times and the energy release rates predicted using the chemical kinetics data set. They show some results of coupled gas dynamics and reactive flow calculations using these models and compare with experiment. They find that the induction parameter model reproduces the experimental results well while using less than 5% of the computational time of the chemical kinetics model.

Clifford, L.J.; Milne, A.M.; Murray, B.A. [Univ. of St. Andrews, Fife (United Kingdom). Dept. of Mathematical Sciences] [Univ. of St. Andrews, Fife (United Kingdom). Dept. of Mathematical Sciences

1996-02-01

206

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

NASA Technical Reports Server (NTRS)

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.

Radhakrishnan, K.

1984-01-01

207

Modeling of flows of the products of combustion of hydrocarbon fuels in an impulsive setup of the e xplosive type  

Microsoft Academic Search

In this work, using an impulsive laboratory steup of the explosive type, the authors studied the inversion characteristics of the products of combustion of acetylene-air mixtures. It is known that when such mixtures burn the products contain a significant quantity of molecular oxygen, so that together with the characteristics of the combustion of mixtures with excess oxidizer the authors also

A. B. Britan; A. N. Khmelevskii; V. A. Levin; G. D. Smekhov; A. M. Starik; Yu. V. Tunik

1986-01-01

208

Simplified transport and reduced chemistry models of premixed and nonpremixed combustion  

NASA Astrophysics Data System (ADS)

In this paper we investigate the application of simplified transport models and reduced chemistry approximations to a set of premixed and nonpremixed methane-air flames. The two models we consider are the laminar premixed and the laminar counterflow diffusion flame in a Tsuji configuration. We examine 1) modifications of the governing conservation equations 2) transport model simplifcations and 3) reduced kinetic mechanisms that reduce substantially the CPU costs of these problems without compromising the predictive capabilities of the models. Numerical results focus of flame speeds, extinction strain rates and temperature and species profiles.

Smooke, Mitchell D.; Giovangigli, V.

209

Chemistry Notes.  

ERIC Educational Resources Information Center

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

School Science Review, 1982

1982-01-01

210

Finite rate chemistry and presumed PDF models for premixed turbulent combustion  

SciTech Connect

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

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

2006-09-15

211

Chemistry of flames  

SciTech Connect

Combustion scientists are primarily concerned with the fuels most often burned as energy sources (coal, petroleum products, and natural gas), with the goal of learning to burn them as efficiently, intensely, and cleanly as possible. Discovering those slight rearrangements of chemical bonds that together account for the net chemical transformation is the key to understanding how combustion proceeds. Once these reactions have been defined, the chemist can determine the rate coefficient of each reaction as a function of temperature and assemble the information into flame models. The computer programs that use these models to predict experimental results combine two sets of equations describing (1) the diffusive and reactive rates of change in concentration of all the molecules in the flame and (2) the flow of the reacting gases. Although the details of hydrocarbon-flame models are still disputed, many of their general features are clear and the basic reactions well-known; computer models for methane combustion already include over 100 elementary reactions. Experimental data on NO/sub x/ formation have led to ingenious methods for purifying postcombustion gases. Currently, the two most actively studied processes in combustion chemistry are the formation and oxidation of soot. The synthetic fuels most likely to replace fossil ones will probably contain less hydrogen, making them more prone to produce soot. How to understand and overcome this problem will be the next challenge for combustion chemists and engineers.

Gardiner, W.C. Jr.

1982-02-01

212

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

NASA Technical Reports Server (NTRS)

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.

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

1996-01-01

213

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

PubMed Central

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.

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

214

Low-temperature combustion chemistry of n-butanol: principal oxidation pathways of hydroxybutyl radicals.  

PubMed

Reactions of hydroxybutyl radicals with O2 were investigated by a combination of quantum-chemical calculations and experimental measurements of product formation. In pulsed-photolytic Cl-initiated oxidation of n-butanol, the time-resolved and isomer-specific product concentrations were probed using multiplexed tunable synchrotron photoionization mass spectrometry (MPIMS). The interpretation of the experimental data is underpinned by potential energy surfaces for the reactions of O2 with the four hydroxybutyl isomers (1-hydroxybut-1-yl, 1-hydroxybut-2-yl, 4-hydroxybut-2-yl, and 4-hydroxybut-1-yl) calculated at the CBS-QB3 and RQCISD(T)/cc-pV?Z//B3LYP/6-311++G(d,p) levels of theory. The observed product yields display substantial temperature dependence, arising from a competition among three fundamental pathways: (1) stabilization of hydroxybutylperoxy radicals, (2) bimolecular product formation in the hydroxybutyl + O2 reactions, and (3) decomposition of hydroxybutyl radicals. The 1-hydroxybut-1-yl + O2 reaction is dominated by direct HO2 elimination from the corresponding peroxy radical forming butanal as the stable coproduct. The chemistry of the other three hydroxybutylperoxy radical isomers mainly proceeds via alcohol-specific internal H-atom abstractions involving the H atom from either the -OH group or from the carbon attached to the -OH group. We observe evidence of the recently reported water elimination pathway (Welz et al. J. Phys. Chem. Lett. 2013, 4 (3), 350-354) from the 4-hydroxybut-2-yl + O2 reaction, supporting its importance in ?-hydroxyalkyl + O2 reactions. Experiments using the 1,1-d2 and 4,4,4-d3 isotopologues of n-butanol suggest the presence of yet unexplored pathways to acetaldehyde. PMID:23808372

Welz, Oliver; Zdor, Judit; Savee, John D; Sheps, Leonid; Osborn, David L; Taatjes, Craig A

2013-11-21

215

Health effects of combustion-generated soot and polycyclic aromatic hydrocarbons. Progress report, May 1, 1980-April 30, 1981  

SciTech Connect

Major progress has been made during 1980 in the development and conception of more useful human cell assays for genetic damage, in the identification of the major contributors to mutation of human cells by combustion effluents and in extending the use of the systems previously developed to the study of the mechanisms of chemical mutation of human cells.

Thilly, W.G.

1981-05-01

216

Influence of oxygen content in the fuel mixture on the thermo- and electrophysical combustion properties in laminar hydrocarbon flames  

Microsoft Academic Search

While investigating the effects of the excess oxidizer coefficient on combustion, it was endeavored to undertake a many-slded analysis of the processes involved. In particular~ the following have been investigated: the distributions of the electric potential and of temperature [i], of the positive ions [2], of the hydrogen radical [3], of the excited particles CH* and C'2 [4], and of

B. S. Fialkov; N. D. Shcherbakov; N. K. Akst; M. D. Ostrovskii

1984-01-01

217

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

PubMed

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

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

2002-02-15

218

In-cylinder unburned hydrocarbon visualization during low-temperature compression-ignition engine combustion using formaldehyde PLIF  

Microsoft Academic Search

Formaldehyde (H2CO) is visualized by planar laser-induced fluorescence (PLIF) in a heavy-duty direct-injection diesel engine to better understand the sources of unburned hydrocarbon (UHC) emissions. H2CO is used as a tracer for UHC based on chemical kinetic simulations, which show that after the first-stage of ignition, the evolution of H2CO is very similar to that of UHC in the bulk

Thierry Lachaux; Mark P. B. Musculus

2007-01-01

219

Heat loss reduction and hydrocarbon combustion in ultra-micro combustors for ultra-micro gas turbines  

Microsoft Academic Search

For the development of ultra-micro combustors for Ultra-Micro Gas Turbines (UMGT), heat loss reduction and hydrocarbon fuel use are the key issues. An approach for reducing the effect of heat loss in ultra-micro combustors was proposed. The heat loss ratio (HLR), which was defined as the ratio of heat loss rate from a combustor to heat release rate in the

Takashi Sakurai; Saburo Yuasa; Taku Honda; Shoko Shimotori

2009-01-01

220

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

SciTech Connect

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.

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

2011-01-01

221

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

NASA Astrophysics Data System (ADS)

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 (4118'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.

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

2013-12-01

222

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

SciTech Connect

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.

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

2011-01-01

223

Combustion Processes Under Microgravity Conditions  

NASA Astrophysics Data System (ADS)

Introduction Classification of Combustion Processes Premixed Flames Diffusion Flames Condensed-Fuel Combustion Flame Balls Alcohol Droplet Combustion Alcohol Combustion Chemistry Methanol Flame Extinction Potential Resolution of a Paradox Other Combustion Phenomena Learned from Experiments Under Microgravity - Conditions Combustion Topics of Future Promise for Microgravity Investigation Premixed-Flame Instabilities Flammability Limits Ignition Flame Extinction Soot Production Flame Spread Along Fuel Rods Pollutant Production in Combustion Conclusions

Williams, F. A.

224

Roadside and rooftop measurements of polycyclic aromatic hydrocarbons in PM 2.5 in urban Guangzhou: Evaluation of vehicular and regional combustion source contributions  

NASA Astrophysics Data System (ADS)

Concurrent sampling of PM 2.5 aerosol at a roadside of heavy traffic (1.2 m above ground) and on a nearby rooftop (50 m above ground) was conducted at a same location in urban Guangzhou in September, October 2006 and January 2007. The samples were analyzed for eighteen polycyclic aromatic hydrocarbons (PAHs), together with major aerosol constituents and certain organic tracers for vehicular emissions (hopanes) and biomass burning (levoglucosan). Elemental carbon (EC) and hopanes were observed to be lower by 21-38% and 28-84%, respectively, at the rooftop than the roadside, confirming vehicular emissions as a significant local PM source. On the other hand, sulfate showed little vertical gradient, consistent with its secondary origin and its regional characteristics. The roadside-rooftop sample pairs have provided an opportunity in evaluating relative contributions of vehicular emissions and regional sources to ambient PAHs in this urban location. Concentrations of the total PAHs were 43% lower at rooftop in the September 2006 samples while they were at similar levels between rooftop and roadside in the October 2006 and January 2007 samples. Sources of PAHs were investigated through comparing ambient data of PAH isomer pairs and PAH/EC ratios with relevant source profiles including those of Guangzhou roadway tunnel emissions, rice straw/sugarcane leave combustion, and industrial coal combustion. The 4-ring PAHs such as pyrene and fluoranthene had a shift in their dominating source from vehicular emissions in September and October to regional combustion source in January. A few major 5- and 6-ring PAHs such as benzo[ghi]perylene and indeno[1,2,3-cd]pyrene were likely heavily influenced by regional biomass burning emissions in all three sampling months. Benzo(a)pyrene-equivalent carcinogenic potency (BaP eq) was calculated to evaluate the cancer risk of carcinogenic PAHs on the public. BaP eq levels in PM 2.5 were significantly higher at the roadside than those at the rooftop in September; however, levels of BaP eq at the rooftop were drastically elevated and became comparable to those at the roadside in October and January due to regional sources dominating the carcinogenic PAHs. This suggests that it is important to control regional combustion sources to reduce air pollution-related health risk in urban Guangzhou.

Gao, Bo; Yu, Jian-Zhen; Li, Shu-Xian; Ding, Xiang; He, Quan-Fu; Wang, Xin-Ming

2011-12-01

225

Forensic Chemistry  

NASA Astrophysics Data System (ADS)

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

Bell, Suzanne

2009-07-01

226

Forensic chemistry.  

PubMed

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. PMID:20636064

Bell, Suzanne

2009-01-01

227

Initiation of Hydrocarbon and Nitrile Chemistry in the Upper Atmospheres and Ionospheres of Titan and the Giant Planets  

Microsoft Academic Search

Excitation, ionization, and fragmentation of methane initiate the creation and evolution of the complex mixtures of hydrocarbons and nitriles in the upper atmospheres and ionospheres of Titan and the giant planets. Key initial processes are photoabsorption, photodissociation, photoionization by solar ultraviolet radiation, as well as ion-molecule reactions with atomic and molecular nitrogen and hydrogen ions. The overall cross sections and

David L. Huestis

2008-01-01

228

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

Microsoft Academic Search

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

J. S. Gaffney; N. A. Marley

1993-01-01

229

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

NASA Technical Reports Server (NTRS)

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.

Bittker, D. A.

1979-01-01

230

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

PubMed Central

Biomass pellets are emerging as a cleaner alternative to traditional biomass fuels. The potential benefits of using biomass pellets include improving energy utilization efficiency and reducing emissions of air pollutants. To assess the environmental, climate, and health significance of replacing traditional fuels with biomass pellets, it is critical to measure the emission factors (EFs) of various pollutants from pellet burning. However, only a few field measurements have been conducted on the emissions of carbon monoxide (CO), particulate matter (PM), and polycyclic aromatic hydrocarbons (PAHs) from the combustion of pellets. In this study, pine wood and corn straw pellets were burned in a pellet burner (2.6 kW) and the EFs of CO, organic carbon, elemental carbon, PM, and PAHs (EFCO, EFOC, EFEC, EFPM, and EFPAH) were determined. The average EFCO, EFOC, EFEC, and EFPM were 15201170, 8.6811.4, 11.28.7, and 18887 mg/MJ for corn straw pellets, and 266137, 5.747.17, 2.021.57, and 71.054.0 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 1.020.64 and 0.5060.360 mg/MJ, respectively. The secondary side air supply in the pellet burner did not change the EFs of most pollutants significantly (p > 0.05). The only exceptions were EFOC and EFPM for pine wood pellets because of reduced combustion temperatures with the increased air supply. In comparison with EFs for the raw pine wood and corn straw, EFCO, EFOC, EFEC, and EFPM for pellets were significantly lower than those for raw fuels (p < 0.05). However, the differences in EFPAH were not significant (p > 0.05). Based on the measured EFs and thermal efficiencies, it was estimated that 95, 98, 98, 88, and 71% reductions in the total emissions of CO, OC, EC, PM, and PAHs could be achieved by replacing the raw biomass fuels combusted in traditional cooking stoves with pellets burned in modern pellet burners.

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

2012-01-01

231

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

PubMed

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

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

2012-06-01

232

The Influence of Hydrocarbon and CO2 on the Reversibility of Li-O2 Chemistry Using In Situ Ambient Pressure X-ray Photoelectron Spectroscopy  

SciTech Connect

Identifying fundamental barriers that hinder reversible lithium oxygen (Li O2) redox reaction is essential for developing efficient and long lasting rechargeable Li O2 batteries. Addressing these challenges is being limited by parasitic reactions in the carbon based O2 electrode with aprotic electrolytes. Understanding the mechanisms of these parasitic reactions is hampered by the complexity that multiple and coupled parasitic reactions involving carbon, electrolytes, and Li O2 reaction intermediates/products can occur simultaneously. In this work, we employed solid state cells free of carbon and aprotic electrolytes to probe the influence of surface adventitious hydrocarbons and carbon dioxide (CO2) on the reversibility of the Li O2 redox chemistry using in situ synchrotron based ambient pressure X ray photoelectron spectroscopy. Direct evidence was provided, for the first time, that surface hydrocarbons and CO2 irreversibly react with Li O2 reaction intermediates/ products such as Li2O2 and Li2O, forming carboxylate and carbonate based species, which cannot be removed fully upon recharge. The slower Li2O2 oxidation kinetics was correlated with increasing coverage of surface carbonate/ carboxylate species. Our work critically points out that materials design that mitigates the reactivity between Li O2 reaction products and common impurities in the atmosphere is needed to achieve long cycle life Li O2 batteries.

Lu, Yi-chun [Massachusetts Institute of Technology (MIT)] [Massachusetts Institute of Technology (MIT); Crumlin, Ethan [Massachusetts Institute of Technology (MIT)] [Massachusetts Institute of Technology (MIT); Carney, Thomas J [ORNL] [ORNL; Baggetto, Loic [ORNL] [ORNL; Veith, Gabriel M [ORNL] [ORNL; Dudney, Nancy J [ORNL] [ORNL; Liu, Zhi [Lawrence Berkeley National Laboratory (LBNL)] [Lawrence Berkeley National Laboratory (LBNL); Shao-Horn, Yang [Massachusetts Institute of Technology (MIT)] [Massachusetts Institute of Technology (MIT)

2013-01-01

233

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

SciTech Connect

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

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

1994-03-01

234

An investigation of molybdenum and molybdenum oxide catalyzed hydrocarbon formation reactions. [Surface chemistry of ethylene oxide on Pd(111)  

SciTech Connect

Progress was made in the following four areas: activity of model catalyst (Mo oxides) for olefin metathesis (2 C[sub 3]H[sub 6] [r arrow] C[sub 4]H[sub 8] + C[sub 2]H[sub 4]); kinetics of Mo(100)-catalyzed olefin metathesis; surface chemistry of ethylene oxide on Pd(111); and uv source construction.

Not Available

1993-01-01

235

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

ERIC Educational Resources Information Center

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

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

2007-01-01

236

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

NASA Astrophysics Data System (ADS)

A set of 16 priority polycyclic aromatic hydrocarbons (PAH) associated with particulate matter (PM), emitted by a diesel engine fueled with petroleum diesel and a 15%-vol. palm oil methyl ester blend with diesel (B15), were determined. PM was filtered from a sample of the exhaust gas with the engine running at a steady speed and under no load. PAH were extracted from the filters using the Soxhlet technique, with dichloromethane as solvent. The extracts were then analyzed by gas chromatography using a flame ionization detector (FID). No significant difference was found between PM mass collected when fueled with diesel and B15. Ten of the 16 PAH concentrations were not reduced by adding biodiesel: Benz(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, chrysene, dibenz(a,h)anthracene, fluoranthene, fluorene, indeno(1,2,3-c,d)pyrene, naphthalene and phenanthrene. The acenaphthene, acenaphthylene and anthracene concentrations were 45%-80% higher when using diesel, whereas those for benzo(k)fluoranthene, benzo(g,h,i)perylene and pyrene were 30%-72% higher when using the B15 blend. Even though the 16 priority-PAH cumulative concentration increased when using the B15 blend, the total toxic equivalent (TEQ) concentration was not different for both fuels.

Rojas, Nestor Y.; Milquez, Harvey Andrs; Sarmiento, Hugo

2011-11-01

237

Global simulation of tropospheric O 3 NO x -hydrocarbon chemistry 2. Model evaluation and global ozone budget  

Microsoft Academic Search

Results from a global three-dimensional model for tropospheric O3-NOx-hydro- carbon chemistry are presented and evaluated with surface, ozonesonde, and aircraft measurements. Seasonal variations and regional distributions of ozone, NO, peroxyacetylni- trate (PAN), CO, ethane, acetone, and H20 2 are examined. The model reproduces observed NO and PAN concentrations to within a factor of 2 for a wide range of tropospheric

Yuhang Wang; Jennifer A. Logan; Daniel J. Jacob

1998-01-01

238

Sandia Combustion Research: Technical review  

SciTech Connect

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

NONE

1995-07-01

239

Real-time measurements of particulate matter and polycyclic aromatic hydrocarbon emissions from stationary combustion sources used in oil and gas production  

SciTech Connect

Particulate matter emissions and some components of the particles were measured in the exhaust from combustion equipment used in oil and gas production operations near Bakersfield, California. The combustion sources included a 22.5 MW (electric) turbine generator, a 342-Bhp rich-burn spark ignition engine, and a 50 million Btu/h steam generator, all fired using natural gas. The particle components and measurement techniques were as follows: (1) Calcium, magnesium, sodium, silicon, and iron were measured using laser-induced breakdown spectroscopy (LIBS), (2) particle-bound polycyclic aromatic hydrocarbons (PAH) were detected using the charge produced by photoionization, (3) particles having sizes between 0.1 and 7.5 {micro}m were counted using an instrument based on light scattering, and (4) total particulate matter was measured according to US EPA Method 5. Not all of the methods were applied to all of the sources. Measurements were also made in the ambient air near the combustion air inlets to the units, for comparison with the concentrations in the exhaust, but the inlet and outlet measurements were not done simultaneously. Calcium, sodium, and silicon were found in the exhaust from the steam generator at concentrations similar to those in the ambient air near the inlet to the burner. Sodium and silicon were observed in the engine exhaust at levels a factor of four higher than their concentrations in the air. The principal metal observed in the engine exhaust was calcium, a component of the lubricating oil, at a concentration of 11.6 {micro}g/m{sup 3}. The air entering the gas turbine is filtered, so the average concentrations of metals in the turbine exhaust under steady operating conditions were even lower than in the air. During start-up following a shut-down to wash the turbine, silicon and iron were the major species in the stack, at concentrations of 6.4 and 16.2 {micro}g/m{sup 3}, respectively. A possible source of silicon is the water injected into the turbine for NO{sub x} control. Iron-containing particles are expected to be scale from ferrous metals. A commercial photoelectric aerosol sensor was used to measure PAH adsorbed on particles in the exhaust from the steam generator and the rich-burn engine. The conversion of the instrument readings to PAH concentrations is dependent upon the specific distribution of PAH species present. Using the typical calibration factor recommended by the instrument manufacturer, the estimated average concentration of particle-bound PAH was below the instrument detection limit (3--10 ng/m{sup 3}) in the stack gas from the steam generator, and was estimated to be 0.045--0.15 {micro}g/m{sup 3} in the exhaust from the rich-burn engine. Particle mass concentrations estimated from number concentrations determined using the particle counting and sizing instrument were only small fractions of the concentrations measured using Method 5. This is thought to be due primarily to the limited range over which size was quantified (0.1 to 7.5 {micro}m) and the poor efficiency with which the sampling system transferred large particles.

D. w. Hahn; K. r. Hencken; H. A. Johnsen; J. R. Ross; P. M. Walsh

1998-12-10

240

Effects of Water Vapor and CO2 Addition on Combustion Characteristics for Lean Hydrocarbon-Air Mixtures under Normal and Microgravity Conditions  

Microsoft Academic Search

Experiments on combustion of extremely lean mixtures in the vicinity of flammability limits have acquired importance from the viewpoint of development of new kinds of combustion systems having low fuel consumption and low emissions. Furthermore, the determination of combustion characteristics for vapor addition under normal gravity and microgravity is very important for control of safety engineering in the space. In

Y. SHIBATA; T. KAWAKAMI; A. TEODORCZYK

241

Combustor nozzle for a fuel-flexible combustion system  

DOEpatents

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

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

2011-03-22

242

The chemistry of elemental events of catalytic conversions of hydrocarbons under the effect of transition-metal compounds  

SciTech Connect

The composition of the products of decomposition of organic compounds of a number of transition metals at the time of their formation was investigated, and it was found that: a) decomposition of methyl derivatives of Mo and W primarily takes place based on the mechanism of ..cap alpha..-disproportionation with formation of carbene and carbyne fragments; b) decomposition of benzyl and neophyl derivatives of neodymium and yttrium in THF quantitatively takes place with formation of stable carbene (carbyne) complexes; c) decomposition of trimethylsilyl(germyl)methyl derivatives of W, Mo, Ta, Re, Nb, Rh, Pd, and Pt is accompanied by formation of complexes containing carbene fragments to two types: (CH/sub 3/)/sub 3/SiCH: and CH/sub 2/: (in the case of W, Mo, Ta, Nb, and Rh compounds, this pathway of decomposition is determining); d) in the reaction of benzylmagnesium chloride with Mo, W, Re, Rh, Pt, and Pd chlorides, significant quantities of toluene, the product of ..cap alpha..-disproportionation of benzyl groups, and some quantities of stilbene and tolan, the products of recombination of carbene and carbyne fragments, are formed. Results based on the data in the literature and the data obtained in the present study concerning the mechanism of decomposition of organic compounds of transition metals, hypotheses were advanced concerning the chemistry of the elemental events in catalytic reactions taking place through organometallic compounds (hydrogenation, dehydrogenation, skeletal isomerization, and deuterium exchange).

Dolgoplosk, B.A.; Oreshkin, I.A.; Tinyakova, E.I.; Yakovlev, V.A.

1982-11-20

243

High Temperature Chemical Kinetic Combustion Modeling of Lightly Methylated Alkanes  

SciTech Connect

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.

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

2011-03-01

244

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)

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 a new laser-based strain-rate and vorticity technique for the time-resolved measurement of vorticity and strain-rates in turbulent flows.

Otugen, M. Volkan

1997-01-01

245

Chemical-looping combustion a thermodynamic study  

Microsoft Academic Search

The poor performance of internal combustion (IC) engines can be attributed to the departure from equilibrium in the combustion process. This departure is expressed numerically, as the difference between the working fluid's temperature and an ideal 'combustion tempera- ture', calculated using a simple expression. It is shown that for combustion of hydrocarbons to be performed reversibly in a single reaction,

N R McGlashan

2008-01-01

246

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

NASA Astrophysics Data System (ADS)

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 between results obtained by CHN analyzer and other applied methods, linear regression equations for the recalculation of SOC concentration were developed.

?iri?, Vladimir; Manojlovi?, Maja; Beli?, Milivoj; Nei?, Ljiljana; varc-Gaji?, Jaroslava; Sitaula, Bishal K.

2014-05-01

247

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

SciTech Connect

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

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

1980-11-01

248

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

SciTech Connect

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

Dryer, F.L.; Brezinsky, K.

1990-09-01

249

POLYCYCLIC AROMATIC HYDROCARBON (PAH) SIZE DISTRIBUTIONS IN AEROSOLS FROM APPLIANCES OF RESIDENTIAL WOOD COMBUSTION AS DETERMINED BY DIRECT THERMAL DESORPTION - GC/MS  

EPA Science Inventory

The paper describesd a direct thermal desorption (TDS) approach to determine the PAH composition (MW = 202-302 amu) in size-segregated aerosols from residential wood combustion (RWC). Six combustion tests are performed with two highly available wood fuel varieties, Douglas-fir (P...

250

Hydrocarbon pneumonia  

MedlinePLUS

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

251

Applicability of heat transfer equations to hydrogen combustion  

Microsoft Academic Search

Previous research by the authors showed that hydrogen combustion exhibits a higher cooling loss to the combustion chamber wall of an internal combustion engine compared to hydrocarbon combustion because of its higher burning velocity and shorter quenching distance. The high cooling loss means that reduction of the cooling loss is essential to establish a high thermal efficiency in hydrogen combustion

Toshio Shudo; Hiroyuki Suzuki

2002-01-01

252

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

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

Cross, Roger T.; Price, Ronald F.

2001-01-01

253

Combustion structure of free and wall-impinging diesel jets by simultaneous laser-induced fluorescence of formaldehyde, poly-aromatic hydrocarbons, and hydroxides  

Microsoft Academic Search

The structure of combusting diesel jets in low-temperature conditions is studied using laser-induced fluorescence (LIF). A single-hole common rail diesel injector is used, which allows high injection pressures up to 120 MPa. Visualizations are performed in a high-pressure, high-temperature cell that is designed to reproduce the typical thermodynamic conditions in the combustion chamber of a diesel engine. Planar LIF of

G Bruneaux

2008-01-01

254

Real-time measurements of particulate matter and polycyclic aromatic hydrocarbon emissions from stationary combustion sources used in oil and gas production  

Microsoft Academic Search

Particulate matter emissions and some components of the particles were measured in the exhaust from combustion equipment used in oil and gas production operations near Bakersfield, California. The combustion sources included a 22.5 MW (electric) turbine generator, a 342-Bhp rich-burn spark ignition engine, and a 50 million Btu\\/h steam generator, all fired using natural gas. The particle components and measurement

D. w. Hahn; K. r. Hencken; H. A. Johnsen; J. R. Ross; P. M. Walsh

1998-01-01

255

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

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.

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

1993-01-01

256

Rate constants for the reacion C4H radical with various hydrocarbons at very low temperatures relevant to the atmospheric chemistry of Titan and other astronomical sources  

NASA Astrophysics Data System (ADS)

There is a huge interest on the satellite of Saturn, Titan, because its atmosphere is probably comparable to our primitive atmosphere. This particular attention has been enhanced by the recent Cassini-Huygens mission that should significantly increase our knowledge about the atmospheres composition (especially for the minority species) and the complex chemistry that takes place. The atmosphere of Titan is mainly composed of molecular nitrogen with a notable fraction of methane (1.5 - 5 %). Many organic compounds have been detected and the active photochemistry taking place in the upper atmosphere is supposed to be responsible for the haze that hides Titan's surface. According to photochemical models, diacetylene C4H2 production is initiated by the photodissociation of acetylene C2H2 (a product of methane photolysis) with the following mechanism: C2H2 + h? ? C2H + H(h? < 217nm) C2H + C2H2 ? C4H2 + H Diacetylene (also called butadiyne) is the first of the polyynes series proposed as a route of formation of the haze particles present in the upper atmosphere. Photolysis of diacetylene can leads to a large amount of radicals including C4H that can react to form longer carbonated chain. Up to now, in photochemical models, the kinetics of C4H is assumed to be the same than C2H. This is however a highly speculative assumption. It is crucial, therefore to determine the rate constants of the reactions involving C4H at low temperatures, especially as this radical has been detected in many important astronomical sources (diffuse gas, dark molecular clouds and circumstellar envelopes). The CRESU technique (Cintique de Raction en Ecoulement Supersonique Uniforme) based on a gas expansion through a Laval nozzle has been used to generate a cold supersonic flow. Kinetics measurements were achieved using PLP (Pulsed Laser Photolysis) LIF (Laser Induced Fluorescence) technique.We present the first results on the kinetics of C4H reactions with several hydrocarbons such as C2H2, C2H4, C2H6 and C4H2.

Berteloite, Coralie; Le Picard, Sbastien D.; Canosa, Andr; Sims, Ian R.

257

QUANTITATIVE ANALYSIS OF POLYNUCLEAR AROMATIC HYDROCARBONS IN LIQUID FUELS  

EPA Science Inventory

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

258

Modeling the combustion behavior of hazardous waste in a rotary kiln incinerator.  

PubMed

Hazardous wastes have complex physical forms and chemical compositions and are normally incinerated in rotary kilns for safe disposal and energy recovery. In the rotary kiln, the multifeed stream and wide variation of thermal, physical, and chemical properties of the wastes cause the incineration system to be highly heterogeneous, with severe temperature fluctuations and unsteady combustion chemistry. Incomplete combustion is often the consequence, and the process is difficult to control. In this article, modeling of the waste combustion is described by using computational fluid dynamics (CFD). Through CFD simulation, gas flow and mixing, turbulent combustion, and heat transfer inside the incinerator were predicted and visualized. As the first step, the waste in various forms was modeled to a hydrocarbon-based virtual fuel mixture. The combustion of the simplified waste was then simulated with a seven-gas combustion model within a CFD framework. Comparison was made with previous global three-gas combustion model with which no chemical behavior can be derived. The distribution of temperature and chemical species has been investigated. The waste combustion model was validated with temperature measurements. Various operating conditions and the influence on the incineration performance were then simulated. Through this research, a better process understanding and potential optimization of the design were attained. PMID:16194906

Yang, Yongxiang; Pijnenborg, Marc J A; Reuter, Markus A; Verwoerd, Joep

2005-01-01

259

Chemistry of the natural atmosphere  

Microsoft Academic Search

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

Peter Warneck

1988-01-01

260

Fuel property effects on engine combustion processes. Final report  

SciTech Connect

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

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

1995-04-27

261

Combustion and Emissions  

NSDL National Science Digital Library

A flickering candle lights the way for a scientific investigation. This lesson uses hands-on demonstrations and web-based presentations to explore the science of combustion. Students become environmental experts as they learn about combustion emissions and how they affect human health and the environment. The lesson would be useful for physics and chemistry for grades 7-12 and would take multiple class periods to cover in full.

2013-07-01

262

Determination of the temperature and concentrations for the products of combustion of a hydrocarbon fuel on the basis of their infrared self-radiation  

Microsoft Academic Search

A measuring system has been developed and a procedure has been proposed for determining the temperature of gas flows and the concentrations of the products of combustion of organic fuels on the basis of the spectral radiationabsorption method. A gas multi-wavelength (1.84.8?m) pyrometerphotometer has been created for measuring the self-radiation of gas flows and transmission of probing radiation from a

E Vitkin; O Zhdanovich; V Tamanovich; V Senchenko; V Dozhdikov; M Ignatiev; I Smurov

2002-01-01

263

Radiation Chemistry  

NASA Astrophysics Data System (ADS)

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.

Wojnrovits, L.

264

Chemical aspects of in-situ combustion--heat of combustion and kinetics  

Microsoft Academic Search

After general remarks on the oxidation reactions of hydrocarbons involved in in situ combustion, the heat releases are estimated and a formula is derived for computing the heat of combustion in the high temperature zone. Then a theoretical discussion of reaction kinetics in porous media is presented and applied to the in situ combustion processes. It is observed that there

J. G. Burger; B. C. Sahuquet

1971-01-01

265

Synthetic fuel aromaticity and staged combustion  

SciTech Connect

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.

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

1982-11-15

266

Simulation of transient turbulent methane jet ignition and combustion under engine-relevant conditions using conditional source-term estimation with detailed chemistry  

Microsoft Academic Search

The ignition and combustion processes of transient turbulent methane jets under high-pressure and moderate temperature conditions were simulated using a computationally efficient combustion model. Closure for the mean chemical source-terms was obtained with Conditional Source-term Estimation (CSE) using first conditional moment closure in conjunction with a detailed chemical kinetic mechanism, which was reduced to a Trajectory-Generated Low-Dimensional Manifold (TGLDM). The

J. Huang; W. K. Bushe

2007-01-01

267

Sedimentary polycyclic aromatic hydrocarbons: the historical record  

Microsoft Academic Search

Polycyclic aromatic hydrocarbons in three sections of a dated sediment core from Buzzards Bay, Massachusetts, have been analyzed by gas chromatographic mass spectrometry. This historical information suggests that sedimentary polycyclic aromatic hydrocarbons, at least at this location, result primarily from the anthropogenic combustion of fossil fuels.

R. A. Hites; R. E. LaFlamme; J. W. Farrington

1977-01-01

268

Organic Experiments for Introductory Chemistry.  

ERIC Educational Resources Information Center

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)

Rayner-Canham, Geoff

1985-01-01

269

Combustion Fundamentals Research  

NASA Technical Reports Server (NTRS)

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.

1984-01-01

270

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

NASA Astrophysics Data System (ADS)

Detailed chemical kinetic modeling based on computational quantum chemistry has been quite successful in making quantitative predictions about some systems, particularly the combustion of small hydrocarbons and certain areas of atmospheric chemistry. The gas phase chemistry of many processes in high-temperature inorganic systems, from materials synthesis to propulsion to waste incineration, could in principle be modeled with equal or greater success using detailed chemical kinetic modeling. This contribution provides examples from our own work of how computational quantum chemistry can be used in developing gas phase reaction mechanisms for modeling of high temperature materials processing. In the context of CVD of silicon from dichlorosilane, CVD of alumina from AlCl3/H2/CO2 mixtures, and particle nucleation from silane, this detailed chemical kinetic modeling has given us insight into gas phase reaction pathways that we would not likely have gained by other means.

Swihart, Mark T.

2005-02-01

271

The influence of operating conditions on the formation of soot and hydrocarbons in flames  

Microsoft Academic Search

Technical devices for the combustion of hydrocarbons with air are usually designed in a way that they exhibit high reliability and high efficiency. The efficiency is computed from thermodynamic considerations, usually assuming that the combustion products for hydrocarbon-air mixtures are CO and HO and that the combustion takes place in stoichiometric mixtures. Real systems, however, deviate more or less from

1994-01-01

272

Detection of Polycyclic Aromatic Hydrocarbons (PAHs) in Human Breast Milk  

Microsoft Academic Search

Exposure to polycyclic aromatic hydrocarbons can result from numerous sources including dietary as well as environmental. Exposure to polycyclic aromatic hydrocarbons has been well-established through combustion sources, particularly coal-fired power plants, automobile and diesel exhaust emissions, and the burning of fossil fuels. In addition, exposure to polycyclic aromatic hydrocarbons occurs through the intake of tobacco smoke, both mainstream and sidestream,

S. Hunter; S. Myers; P. Radmacher; C. Eno

2010-01-01

273

Factors affecting pore water hydrocarbon concentrations in Puget Sound sediments  

Microsoft Academic Search

Polycyclic aromatic hydrocarbon (PAH) and aliphatic hydrocarbon concentrations have been determined for sediments and associated pore waters collected at 2 sites (11 stations) in Puget Sound, Washington (northwest U.S.A.). These sediments have been contaminated to varying degrees by hydrocarbons from a creosote plant and from various combustion sources. PAH were not detected in pore waters of sediments whose PAH were

Stephen B. Socha; Roy Carpenter

1987-01-01

274

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

PubMed

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

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

2000-09-01

275

Gas Turbine Combustion and Emission Control.  

National Technical Information Service (NTIS)

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...

B. Schetter

1993-01-01

276

Spectral optimization and uncertainty quantification in combustion modeling  

NASA Astrophysics Data System (ADS)

Reliable simulations of reacting flow systems require a well-characterized, detailed chemical model as a foundation. Accuracy of such a model can be assured, in principle, by a multi-parameter optimization against a set of experimental data. However, the inherent uncertainties in the rate evaluations and experimental data leave a model still characterized by some finite kinetic rate parameter space. Without a careful analysis of how this uncertainty space propagates into the model's predictions, those predictions can at best be trusted only qualitatively. In this work, the Method of Uncertainty Minimization using Polynomial Chaos Expansions is proposed to quantify these uncertainties. In this method, the uncertainty in the rate parameters of the as-compiled model is quantified. Then, the model is subjected to a rigorous multi-parameter optimization, as well as a consistency-screening process. Lastly, the uncertainty of the optimized model is calculated using an inverse spectral optimization technique, and then propagated into a range of simulation conditions. An as-compiled, detailed H2/CO/C1-C4 kinetic model is combined with a set of ethylene combustion data to serve as an example. The idea that the hydrocarbon oxidation model should be understood and developed in a hierarchical fashion has been a major driving force in kinetics research for decades. How this hierarchical strategy works at a quantitative level, however, has never been addressed. In this work, we use ethylene and propane combustion as examples and explore the question of hierarchical model development quantitatively. The Method of Uncertainty Minimization using Polynomial Chaos Expansions is utilized to quantify the amount of information that a particular combustion experiment, and thereby each data set, contributes to the model. This knowledge is applied to explore the relationships among the combustion chemistry of hydrogen/carbon monoxide, ethylene, and larger alkanes. Frequently, new data will become available, and it will be desirable to know the effect that inclusion of these data has on the optimized model. Two cases are considered here. In the first, a study of H2/CO mass burning rates has recently been published, wherein the experimentally-obtained results could not be reconciled with any extant H2/CO oxidation model. It is shown in that an optimized H2/CO model can be developed that will reproduce the results of the new experimental measurements. In addition, the high precision of the new experiments provide a strong constraint on the reaction rate parameters of the chemistry model, manifested in a significant improvement in the precision of simulations. In the second case, species time histories were measured during n-heptane oxidation behind reflected shock waves. The highly precise nature of these measurements is expected to impose critical constraints on chemical kinetic models of hydrocarbon combustion. The results show that while an as-compiled, prior reaction model of n-alkane combustion can be accurate in its prediction of the detailed species profiles, the kinetic parameter uncertainty in the model remains to be too large to obtain a precise prediction of the data. Constraining the prior model against the species time histories within the measurement uncertainties led to notable improvements in the precision of model predictions against the species data as well as the global combustion properties considered. Lastly, we show that while the capability of the multispecies measurement presents a step-change in our precise knowledge of the chemical processes in hydrocarbon combustion, accurate data of global combustion properties are still necessary to predict fuel combustion.

Sheen, David Allan

277

Release of polycyclic aromatic hydrocarbons, carbon monoxide and particulate matter from biomass combustion in a wood-fired boiler under varying boiler conditions  

NASA Astrophysics Data System (ADS)

Particulate matter, CO and NO as well as 16 polycyclic aromatic hydrocarbons (PAHs) in both gaseous and particulate phases were measured in the stack of a woodchip-fired 50 kW boiler used for domestic heating. The concentrations of ?PAHs in both gas and particle phases varied from 1.3 to 1631.7 ?g m -3. Mean CO and NO concentrations varied from 96 to 6002 ppm and from 28 to 359 ppm, respectively. The effects of fuel parameters (moisture content (MC) and tree species) and boiler operating conditions on pollutant concentrations were investigated. A relationship was established between ?PAHs in gaseous and particulate phases and CO concentrations. The species of tree used for woodchip was less important than MC and boiler operating conditions in affecting pollutant concentrations. It is recommended that in order to minimise PAH release woodchip fuel should have a low MC, and the boiler should be operated with a load demand (high/moderate heat requirement). Slumber modes when the boiler has no load demand and is effectively a smouldering flame should be avoided. This can be achieved by increasing automatic operation capability of wood-fired boilers, for example, by automatically varying fire rates and having auto-start capabilities. The PAH data obtained from this study is particularly useful in contributing to emissions inventories, modelling, and predictions of ambient air quality.

Bignal, Keeley L.; Langridge, Sam; Zhou, John L.

278

Soot Formation in Combustion Processes (Review)  

Microsoft Academic Search

A review is given of recent papers on the phenomenology, kinetics, and mechanism of soot formation in hydrocarbon combustion;\\u000a the effects of various factors on the formation of polycyclic aromatic hydrocarbons, fullerenes, and soot, low-temperature\\u000a soot formation in cool flames, combustion in electric field, and the paramagnetism of soot particles from an ecological viewpoint\\u000a are considered.

Z. A. Mansurov

2005-01-01

279

Estimating heat of combustion for waste materials  

Microsoft Academic Search

Describes a method of estimating the heat of combustion of hydrocarbon waste (containing S,N,Q,C1) in various physical forms (vapor, liquid, solid, or mixtures) when the composition of the waste stream is known or can be estimated. Presents an equation for predicting the heat of combustion of hydrocarbons containing some sulfur. Shows how the method is convenient for estimating the heat

1982-01-01

280

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

SciTech Connect

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)

Westbrook, Charles K.; Pitz, William J.; Herbinet, Olivier; Silke, Emma J. [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Curran, Henry J. [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); University College of Ireland, Galway (Ireland)

2009-01-15

281

Organic Chemistry of the Atmosphere  

Microsoft Academic Search

This book reviews the information currently available regarding the chemistry of organic compounds in the atmosphere. Topics discussed include methods for collecting organic compounds from the atmosphere, the influence of organic compounds on indoor and outdoor air quality, the chemistry of polycyclic aromatic hydrocarbons, environmental tobacco smoke, organic compounds in rainwater, organic oxysulfur compounds, and the effect of organic compounds

Lee D. Hansen; Delbert J. Eatough

1991-01-01

282

A Novel Philosophy for a First Course in Organic Chemistry.  

ERIC Educational Resources Information Center

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)

Newman, Melvin S.

1982-01-01

283

Nox reduction system utilizing pulsed hydrocarbon injection  

DOEpatents

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.

Brusasco, Raymond M. (Livermore, CA); Penetrante, Bernardino M. (San Ramon, CA); Vogtlin, George E. (Fremont, CA); Merritt, Bernard T. (Livermore, CA)

2001-01-01

284

New technique for calibrating hydrocarbon gas flowmeters  

NASA Technical Reports Server (NTRS)

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.

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

1984-01-01

285

Preliminary assessment of combustion modes for internal combustion wave rotors  

NASA Technical Reports Server (NTRS)

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.

Nalim, M. Razi

1995-01-01

286

Detailed chemical kinetic mechanisms for combustion of oxygenated fuels  

Microsoft Academic Search

Thermodynamic properties and detailed chemical kinetic models have been developed for the combustion of two oxygenates: methyl butanoate, a model compound for biodiesel fuels, and methyl formate, a related simpler molecule. Bond additivity methods and rules for estimating kinetic parameters were adopted from hydrocarbon combustion and extended. The resulting mechanisms have been tested against the limited combustion data available in

E. M. Fisher; W. J. Pitz; H. J. Curran; C. K. Westbrook

2000-01-01

287

On-line measurement of heat of combustion  

Microsoft Academic Search

An experimental method for an on-line measurement of heat of combustion of a gaseous hydrocarbon fuel mixture of unknown composition is developed. It involves combustion of a test gas with a known quantity of air to achieve a predetermined oxygen concentration level in the combustion products. This is accomplished by a feedback controller which maintains the gas volumetric flow rate

S. K. Chaturvedi; H. Chegini

1988-01-01

288

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

SciTech Connect

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

Grout, Ray W [ORNL

2012-01-01

289

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

SciTech Connect

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

Sankaran, R.; Grout, R.

2012-01-01

290

Catalytic Combustion of Syngas  

Microsoft Academic Search

The catalytic combustion of syngas\\/air mixtures over Pt has been investigated numerically in a channel-flow configuration using 2D steady and transient computer codes with detailed hetero-\\/homogeneous chemistry, transport, and heat transfer mechanisms in the solid. Simulations were carried out for syngas compositions with varying H2 and CO contents, pressures of 1 to 15 bar, and linear velocities relevant to power

John Mantzaras

2008-01-01

291

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

PubMed

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

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

292

Soot Formation in Hydrocarbon/Air Laminar Jet Diffusion Flames.  

National Technical Information Service (NTIS)

Soot processes within hydrocarbon/air diffusion flames are important because they affect the durability and performance of propulsion systems, the hazards of unwanted fires, the pollutant and particulate emissions from combustion processes, and the potent...

P. B. Sunderland G. M. Faeth

1994-01-01

293

Hydrocarbon Transport  

NSF Publications Database

... Item - Study on Hydrocarbon Transport in Polar Soils) To: Files (Environment - S.7) (Hazardous ... flow chamber" and natural soil. Freezing fronts were induced from the soil surface downward using ...

294

Combustion noise  

NASA Technical Reports Server (NTRS)

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.

Strahle, W. C.

1977-01-01

295

Mild Combustion  

Microsoft Academic Search

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

Antonio Cavaliere; Mara de Joannon

2004-01-01

296

Combustion Enhancement with a Silent Discharge Plasma  

Microsoft Academic Search

It is well known that the application of an external electric field to a flame can affect its propagation speed, stability, and combustion chemistry (Lawton & Weinberg 1969). External electrodes, arc discharges, and plasma jets have been employed to allow combustible gas mixtures to operate outside their flammability limits by gas heating, injection of free radicals, and field-promoted flame stabilization

Louis Rosocha

2003-01-01

297

Hydrocarbon-enhanced particulate filter regeneration via microwave ignition  

DOEpatents

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.

Gonze, Eugene V. (Pinckney, MI); Brown, David B. (Brighton, MI)

2010-02-02

298

Formation of polycyclic aromatic hydrocarbons in circumstellar envelopes  

NASA Technical Reports Server (NTRS)

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.

Frenklach, Michael; Feigelson, Eric D.

1989-01-01

299

Effects of hydrocarbon substitution on atmospheric hydrogenair flame propagation  

Microsoft Academic Search

In order to evaluate the potential of partial hydrocarbon substitution to improve the safety of hydrogen use in general and the performance of internal combustion engines in particular, the outward propagation and development of surface cellular instability of spark-ignited spherical premixed flames of mixtures of hydrogen, hydrocarbon, and air were experimentally studied at NTP condition in a constant-pressure combustion chamber.

C. K. Law; O. C. Kwon

2004-01-01

300

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

SciTech Connect

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

Dryer, F.L.; Brezinsky, K.

1989-07-01

301

Multiple-site underground magnetic heating of hydrocarbons  

Microsoft Academic Search

A first underground deposit of lignite or coal is heated by magnetic induction to recover hydrocarbon liquids and gases. The carbon remaining is combusted with air and steam to produce a gas which is combusted to generate electrical energy. The electrical energy is transmitted to second underground deposits of oil shale , tar sand or heavy oil, and is used

C. B. Fisher; S. T. Fisher

1982-01-01

302

Organic chemistry of the atmosphere  

SciTech Connect

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

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

1991-01-01

303

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

SciTech Connect

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

Gusinow, M.A. (ed.)

1980-09-01

304

Apparatus for hydrocarbon extraction  

DOEpatents

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.

Bohnert, George W.; Verhulst, Galen G.

2013-03-19

305

Combustion engine. [for air pollution control  

NASA Technical Reports Server (NTRS)

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.

Houseman, J. (inventor)

1977-01-01

306

Method of power generation via coal gasification and liquid hydrocarbon synthesis. [10 claims  

Microsoft Academic Search

Disclosed is an integrated process for the generation of power, particularly electrical power, from a solid carbonaceous material. A solid carbonaceous material is gasified to produce a combustible synthesis gas. A first portion of this synthesis gas is contacted with Fischer-Tropsch and hydrogenation catalysts to produce normally liquid hydrocarbons and a second combustible gaseous stream. Portions of the two combustible

Egan

1976-01-01

307

Multiuser Droplet Combustion Apparatus Developed to Conduct Combustion Experiments  

NASA Technical Reports Server (NTRS)

A major portion of the energy produced in the world today comes from the combustion or burning of liquid hydrocarbon fuels in the form of droplets. However, despite vigorous scientific examinations for over a century, researchers still lack a full understanding of many fundamental combustion processes of liquid fuels. Understanding how these fuel droplets ignite, spread, and extinguish themselves will help us develop more efficient ways of energy production and propulsion, as well as help us deal better with the problems of combustion-generated pollution and fire hazards associated with liquid combustibles. The ability to conduct more controlled experiments in space, without the complication of gravity, provides scientists with an opportunity to examine these complicated processes closely. The Multiuser Droplet Combustion Apparatus (MDCA) supports this continued research under microgravity conditions. The objectives are to improve understanding of fundamental droplet phenomena affected by gravity, to use research results to advance droplet combustion science and technology on Earth, and to address issues of fire hazards associated with liquid combustibles on Earth and in space. MDCA is a multiuser facility designed to accommodate different combustion science experiments. The modular approach permits the on-orbit replacement of droplet combustion principal investigator experiments such as different fuels, droplet-dispensing needles, and droplet-tethering mechanisms. Large components such as the avionics, diagnostics, and base-plate remain on the International Space Station to reduce the launch mass of new experiments. MDCA is also designed to operate in concert with ground systems on Earth to minimize the involvement of the crew during orbit.

Myhre, Craig A.

2001-01-01

308

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

NASA Astrophysics Data System (ADS)

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

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

2009-12-01

309

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

NASA Astrophysics Data System (ADS)

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

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

2009-09-01

310

Advanced Chemistry Basins Model  

SciTech Connect

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.

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

2003-02-13

311

Computational combustion  

Microsoft Academic Search

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

Charles K. Westbrook; Yasuhiro Mizobuchi; Thierry J. Poinsot; Phillip J. Smith; Jrgen Warnatz

2005-01-01

312

Computational Combustion  

Microsoft Academic Search

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

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

2004-01-01

313

Spherical combustion clouds in explosions  

NASA Astrophysics Data System (ADS)

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 pressure field. Turbulent kinetic energy of the combustion cloud decayed due to enstrophy overline{? 2} and dilatation overline{? 2}.

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

2013-05-01

314

Fuel reforming apparatus for use with internal combustion engine  

Microsoft Academic Search

The invention discloses a fuel reforming apparatus for use with an internal combustion engine, comprising hydrocarbon fuel supply means for producing a mixture of hydrocarbon fuel with air in a suitable air-fuel ratio, a burning chamber in which the mixture is ignited and burned, and a reactor which is packed with a catalyst adapted to carry out the catalytic reforming,

M. Noguchi; T. Bunda; T. Tanaka

1978-01-01

315

Plasma chemistry and organic synthesis  

NASA Technical Reports Server (NTRS)

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.

Tezuka, M.

1980-01-01

316

Conversion of methane to higher hydrocarbons in ac nonequilibrium plasmas  

Microsoft Academic Search

The effects of plasma chemistry on the conversion of methane were studied using a dielectric barrier discharge reactor at ambient temperatures. A dielectric barrier discharge reactor generates a nonequilibrium plasma when a sufficiently high voltage is applied across the reactor`s electrodes. Methane molecules are activated at this temperature and coupled to form C hydrocarbons, higher hydrocarbons, and hydrogen. The study

K. Thanyachotpaiboon; S. Chavadej; T. A. Caldwell; L. L. Lobban; R. G. Mallinson

1998-01-01

317

The effect of acoustic oscillations on diffusion combustion of methane  

NASA Astrophysics Data System (ADS)

Aspects of ecological safety related to the combustion of hydrocarbonsin particular, the demand for reducing the content of toxic compounds in combustion productsare extremely topical. In addition, there is still important task of increasing the efficiency of using all kinds of fuel, including hydroarbons. One possible mechanism of controlling combustion processesnamely, the effect of acoustic perturbations on the diffusion combustion of methanehas been considered. The influence of acoustic oscillations on the characteristics of diffusion flame has been studied, and the dependence of the concentration of nitrogen oxides in the combustion products on the acoustic signal frequency has been determined.

Krivokorytov, M. S.; Golub, V. V.; Volodin, V. V.

2012-05-01

318

On-line measurement of heat of combustion  

NASA Technical Reports Server (NTRS)

An experimental method for an on-line measurement of heat of combustion of a gaseous hydrocarbon fuel mixture of unknown composition is developed. It involves combustion of a test gas with a known quantity of air to achieve a predetermined oxygen concentration level in the combustion products. This is accomplished by a feedback controller which maintains the gas volumetric flow rate at a level consistent with the desired oxygen concentration in the products. The heat of combustion is determined from a known correlation with the gas volumetric flow rate. An on-line microcomputer accesses the gas volumetric flow data, and displays the heat of combustion values at desired time intervals.

Chaturvedi, S. K.; Chegini, H.

1988-01-01

319

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

Microsoft Academic Search

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

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

1982-01-01

320

Numerical analysis of supersonic combustion ramjet with upstream fuel injection  

Microsoft Academic Search

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

Raffaele Savino; Giuseppe Pezzella

2003-01-01

321

Low NOx combustion using cogenerated oxygen and nitrogen streams  

DOEpatents

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.

Kobayashi, Hisashi (Putnam Valley, NY) [Putnam Valley, NY; Bool, Lawrence E. (East Aurora, NY) [East Aurora, NY; Snyder, William J. (Ossining, NY) [Ossining, NY

2009-02-03

322

Research on emissions and mitigation of POP's from combustion sources  

Microsoft Academic Search

The environmental consequences of persistent organic pollutants (POP's) are of increasing concern due to the serious health effects on animals and humans including reproduction, development and immunological function. Several major classes of POP's, including polycyclic aromatic hydrocarbons (PAH's), chlorobenzenes, chlorinated dioxins and chlorinated furans, have been identified as products of incomplete combustion (PIC's) produced in trace levels in combustion systems.

C. W. Lee; P. M. Lemieux; B. K. Gullett; J. V. Ryan; J. D. Kilgroe

1998-01-01

323

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

NASA Astrophysics Data System (ADS)

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

Veziroglu, T. N.

324

Laboratory studies of lean combustion  

NASA Technical Reports Server (NTRS)

The fundamental processes controlling lean combustion were observed for better understanding, with particular emphasis on the formation and measurement of gas-phase pollutants, the stability of the combustion process (blowout limits), methods of improving stability, and the application of probe and optical diagnostics for flow field characterization, temperature mapping, and composition measurements. The following areas of investigation are described in detail: (1) axisymmetric, opposed-reacting-jet-stabilized combustor studies; (2) stabilization through heat recirculation; (3) two dimensional combustor studies; and (4) spectroscopic methods. A departure from conventional combustor design to a premixed/prevaporized, lean combustion configuration is attractive for the control of oxides of nitrogen and smoke emissions, the promotion of uniform turbine inlet temperatures, and, possibly, the reduction of carbon monoxide and hydrocarbons at idle.

Sawyer, R. F.; Schefer, R. W.; Ganji, A. R.; Daily, J. W.; Pitz, R. W.; Oppenheim, A. K.; Angeli, J. W.

1977-01-01

325

Combustion and heat transfer: Volume 3 -- Combustion studies. Final report, 8 June 1992--31 December 1997  

Microsoft Academic Search

The objective of the proposed research was to develop a fundamental understanding of the combustion process in a gas turbine combustor. Specifically, the authors performed WSR experiments, vortex-flame interaction studies, flame stabilization research, and studies of turbine blade film cooling. A toroidal WSR was used to study lean blowout (LBO), combustion efficiency, and emissions. They found that fuel hydrocarbons of

D. R. Ballal; F. Takahashi; D. Pestian; W. J. Schmoll; M. Vangsness

1997-01-01

326

Handbook of infrared radiation from combustion gases  

NASA Technical Reports Server (NTRS)

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.

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

1973-01-01

327

Sandia Combustion Research Program: Annual report, 1986  

SciTech Connect

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

Not Available

1986-01-01

328

The role played by self-inhibition in combustion processes  

Microsoft Academic Search

The absence of correlations between the heat of combustion of substances and substance combustion characteristics is shown\\u000a to be caused by the special features of competition between reaction chain branching and termination, including partial participation\\u000a of fuels in the inhibition of their oxidation. By way of example, differences in the characteristics of combustion of hydrocarbons\\u000a and hydrogen at atmospheric pressure

V. V. Azatyan; I. A. Bolodyan; Yu. N. Shebeko; V. Yu. Navtsenya; A. Yu. Shebeko

2006-01-01

329

Hydrocarbon and nonhydrocarbon derivatives of cyclopropane  

NASA Technical Reports Server (NTRS)

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.

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

1953-01-01

330

An experimental study on high temperature and low oxygen air combustion  

Microsoft Academic Search

High temperature preheated and diluted air combustion has been confirmed as the technology, mainly applied to industrial furnaces and kilns, to realize higher thermal efficiency and lower emissions. The purpose of this study was to investigate fundamental aspects of the above-mentioned combustion experimentally and to compare with those in ordinary hydrocarbon combustion with room temperature air. The test items were

W. B. Kim; D. H. Chung; J. B. Yang; D. S. Noh

2000-01-01

331

On-line measurement of heat of combustion. Final report, period ended 30 April 1988  

Microsoft Academic Search

An experimental method for an on-line measurement of heat of combustion of a gaseous hydrocarbon fuel mixture of unknown composition is developed. It involves combustion of a test gas with a known quantity of air to achieve a predetermined oxygen concentration level in the combustion products. This is accomplished by a feedback controller which maintains the gas volumetric flow rate

S. K. Chaturvedi; H. Chegini

1988-01-01

332

Evaporation and ignition of droplets in combustion chambers modeling and simulation  

Microsoft Academic Search

Computer simulation of liquid fuel jet injection into heated atmosphere of combustion chamber, mixture formation, ignition and combustion need adequate modeling of evaporation, which is extremely important for the curved surfaces in the presence of strong heat and mass diffusion fluxes. Combustion of most widely spread hydrocarbon fuels takes place in a gas-phase regime. Thus, evaporation of fuel from the

V. B. Betelin; N. N. Smirnov; V. F. Nikitin; V. R. Dushin; A. G. Kushnirenko; V. A. Nerchenko

333

Combustion detector  

NASA Technical Reports Server (NTRS)

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.

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

1973-01-01

334

Combustion Physics.  

ERIC Educational Resources Information Center

Discusses how physics is used to improve the efficiency of combustion, pointing out that the interdisciplinary topic has applications to problems of real industrial relevance and practical value. (JN)

Jones, A. R.

1985-01-01

335

Emissions from domestic heating oil combustion  

Microsoft Academic Search

Gaseous and particulate emissions from a typical high pressure gun burner were measured while firing differing fuels in a domestic hot air furnace. Emission factors were obtained over a wide range of operating conditions including those with relatively poor combustion. The emission factors for carbon monoxide, hydrocarbons, and nitrogen oxides were 2, 0.5, and 15 lbs\\/1000 gal, respectively, and the

B. J. Kraus; J. F. Coburn

1974-01-01

336

ALTERNATIVE METHODS FOR BIOMASS COMBUSTION CONTROL  

Microsoft Academic Search

The purpose of this paper is to examine alternative methods to improve the control of combustion in industrial moving grate biomass boilers. A review of existing and recently developed methods is presented, especially new gas sensors for CO and unburnt hydrocarbons. The development of a new passive optical method and first results obtained on industrial wood-burning boilers are shown. It

337

Structure-Based Predictive Model For Coal Char Combustion.  

National Technical Information Service (NTIS)

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 t...

Christopher Hadad Eugene Stanley J.M. Calo Robert Essenhigh Robert Hurt

1998-01-01

338

Structure-Based Predictive Model for Coal Char Combustion.  

National Technical Information Service (NTIS)

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) ...

C. M. Hadad J. M. Calo R. H. Essenhigh R. H. Hurt

1998-01-01

339

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

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

340

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

PubMed

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

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

2001-01-01

341

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

ERIC Educational Resources Information Center

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)

Wilbraham, A. C.

1979-01-01

342

Combustion Chemistry of Vibrationally Excited Oxygen.  

National Technical Information Service (NTIS)

We are investigating the use of stimulated resonance Raman pumping to prepare oxygen in selected vibrational states of the ground electronic manifold. This necessitates the development of a laser source capable of producing radiation in the region of the ...

R. B. Miles J. Gelfand H. Rabitz

1984-01-01

343

Organic chemistry on Titan  

NASA Technical Reports Server (NTRS)

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.

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

1979-01-01

344

Prediction of flame velocities of hydrocarbon flames  

NASA Technical Reports Server (NTRS)

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.

Dugger, Gordon L; Simon, Dorothy M

1954-01-01

345

Modeling of Plasma Assisted Combustion  

NASA Astrophysics Data System (ADS)

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).

Akashi, Haruaki

2012-10-01

346

Uncovering the fundamental chemistry of alkyl + O2 reactions via measurements of product formation.  

PubMed

The reactions of alkyl radicals (R) with molecular oxygen (O(2)) are critical components in chemical models of tropospheric chemistry, hydrocarbon flames, and autoignition phenomena. The fundamental kinetics of the R + O(2) reactions is governed by a rich interplay of elementary physical chemistry processes. At low temperatures and moderate pressures, the reactions form stabilized alkylperoxy radicals (RO(2)), which are key chain carriers in the atmospheric oxidation of hydrocarbons. At higher temperatures, thermal dissociation of the alkylperoxy radicals becomes more rapid and the formation of hydroperoxyl radicals (HO(2)) and the conjugate alkenes begins to dominate the reaction. Internal isomerization of the RO(2) radicals to produce hydroperoxyalkyl radicals, often denoted by QOOH, leads to the production of OH and cyclic ether products. More crucially for combustion chemistry, reactions of the ephemeral QOOH species are also thought to be the key to chain branching in autoignition chemistry. Over the past decade, the understanding of these important reactions has changed greatly. A recognition, arising from classical kinetics experiments but firmly established by recent high-level theoretical studies, that HO(2) elimination occurs directly from an alkylperoxy radical without intervening isomerization has helped resolve tenacious controversies regarding HO(2) formation in these reactions. Second, the importance of including formally direct chemical activation pathways, especially for the formation of products but also for the formation of the QOOH species, in kinetic modeling of R + O(2) chemistry has been demonstrated. In addition, it appears that the crucial rate coefficient for the isomerization of RO(2) radicals to QOOH may be significantly larger than previously thought. These reinterpretations of this class of reactions have been supported by comparison of detailed theoretical calculations to new experimental results that monitor the formation of products of hydrocarbon radical oxidation following a pulsed-photolytic initiation. In this article, these recent experiments are discussed and their contributions to improving general models of alkyl + O(2) reactions are highlighted. Finally, several prospects are discussed for extending the experimental investigations to the pivotal questions of QOOH radical chemistry. PMID:16571032

Taatjes, Craig A

2006-04-01

347

Chemistry Notes.  

ERIC Educational Resources Information Center

Describes experiments, demonstrations, activities and ideas relating to various fields of chemistry to be used in chemistry courses of secondary schools. Three experiments concerning differential thermal analysis are among these notes presented. (HM)

School Science Review, 1978

1978-01-01

348

Chemistry Notes  

ERIC Educational Resources Information Center

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)

School Science Review, 1976

1976-01-01

349

Chemistry Notes  

ERIC Educational Resources Information Center

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)

School Science Review, 1972

1972-01-01

350

Bubble Combustion  

NASA Technical Reports Server (NTRS)

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, a computational model developed at Glenn, that simulates the cavitational collapse of a single bubble in a liquid (water) and the subsequent combustion of the gaseous contents inside the bubble. The model solves the time-dependent, compressible Navier-Stokes equations in one-dimension with finite-rate chemical kinetics using the CHEMKIN package. Specifically, parameters such as frequency, pressure, bubble radius, and the equivalence ratio were varied while examining their effect on the maximum temperature, radius, and chemical species. These studies indicate that the radius of the bubble is perhaps the most critical parameter governing bubble combustion dynamics and its efficiency. Based on the results of the parametric studies, we plan on conducting experiments to study the effect of ultrasonic perturbations on the bubble generation process with respect to the bubble radius and size distribution.

Corrigan, Jackie

2004-01-01

351

Biofuels combustion.  

PubMed

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

Westbrook, Charles K

2013-01-01

352

Compliant Walled Combustion Devices.  

National Technical Information Service (NTIS)

Combustion devices described herein comprise a compliant combustion chamber wall or segment. The compliant segment deforms during combustion in the combustion chamber. Some devices may include a compliant wall configured to stretch responsive to pressure ...

H. Prahlad J. Helm R. E. Pelrine S. Oh S. E. Stanford

2005-01-01

353

Forensic Chemistry  

Microsoft Academic Search

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

Suzanne Bell

2009-01-01

354

Organic Chemistry  

NSDL National Science Digital Library

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

355

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

DOEpatents

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

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

2007-10-30

356

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

NASA Technical Reports Server (NTRS)

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.

Nguyen, H. L.

1991-01-01

357

PCI: Toward cleaner combustion  

SciTech Connect

Westinghouse Electric Corp. and Precision Combustion Inc. (PCI) have announced that they will cooperate on the development of a catalytic combustion system for possible use in the upcoming A.T.S. engine. As we learned during a recent visit, this is only one of many catalyst applications being explored by PCI. This paper discuses these developments and applications, which include: an ultra-low-emission catalytic converter for reciprocating auto exhaust systems, which would meet the American U.L.E.V. (ultra-low emission vehicle) regulations (0.2 gm/mi NO{sub x}, 1.7 gm/mi CO, 0.04 gm/mi hydrocarbons). This is named Microlith{sup TM}; a `flashback arrestor` to limit flash-back in gas turbines; a catalytic igniter, particularly suited to aero gas turbines. This would replace the spark ignition system, and would provide lean flame stabilization, as well as re-ignition in case of a flameout; a catalytic glow plug for diesel engines; and a catalytic muffler for very small reciprocating engines, such as those on lawn mowers.

NONE

1997-01-01

358

Early events in radiation chemistry and in photoionization  

SciTech Connect

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

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

1992-12-31

359

Early events in radiation chemistry and in photoionization  

SciTech Connect

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

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

1992-01-01

360

CLUSTER CHEMISTRY  

SciTech Connect

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

Muetterties, Earl L.

1980-05-01

361

Computational Chemistry for Chemistry Educators  

NSDL National Science Digital Library

This is a 15-session course on the technologies, techniques, and tools of computational chemistry. By using the same computational tools as research computational chemists, educators will have the opportunity to study chemistry in a manner very different than traditional teaching and education in chemistry.

Institute, Shodor C.

362

Polycyclic aromatic hydrocarbons in the diet  

Microsoft Academic Search

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

David H Phillips

1999-01-01

363

Electrically heated particulate filter regeneration using hydrocarbon adsorbents  

DOEpatents

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.

Gonze, Eugene V [Pinckney, MI

2011-02-01

364

Determination of stable carbon and hydrogen isotopes of light hydrocarbons  

Microsoft Academic Search

A combined system for the measurement of ¹³C\\/¹²C and D\\/H ratios on light hydrocarbons (C-C) and CO is described. The system is designed for natural gas and sediment gas analyses. It comprises gas chromatographic separation with online combustion of hydrocarbons to CO and HO, reduction of HO to H on zinc in closed ampules, and mass spectrometric determination of isotope

Ingolf. Dumke; Eckhard. Faber; Juergen. Poggenburg

1989-01-01

365

Propellant Chemistry for CFD Applications  

NASA Technical Reports Server (NTRS)

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.

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

1996-01-01

366

Aviation combustion toxicology: an overview.  

PubMed

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

Chaturvedi, Arvind K

2010-01-01

367

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

NASA Technical Reports Server (NTRS)

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.

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

1999-01-01

368

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

NASA Astrophysics Data System (ADS)

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

Weiland, Karen J.

2000-01-01

369

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

NASA Astrophysics Data System (ADS)

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.

Borrs, Esther; Tortajada-Genaro, Luis A.; Vzquez, Monica; Zielinska, Barbara

2009-12-01

370

Trace Chemistry  

NASA Technical Reports Server (NTRS)

The goals of the trace chemistry group were to identify the processes relevant to aerosol and aerosol precursor formation occurring within aircraft gas turbine engines; that is, within the combustor, turbine, and nozzle. The topics of discussion focused on whether the chemistry of aerosol formation is homogeneous or heterogeneous; what species are important for aerosol and aerosol precursor formation; what modeling/theoretical activities to pursue; what experiments to carry out that both support modeling activities and elucidate fundamental processes; and the role of particulates in aerosol and aerosol precursor formation. The consensus of the group was that attention should be focused on SO2, SO3, and aerosols. Of immediate concern is the measurement of the concentration of the species SO3, SO2, H2SO4 OH, HO2, H2O2, O, NO, NO2, HONO, HNO3, CO, and CO2 and particulates in various engines, both those currently in use and those in development. The recommendation was that concentration measurements should be made at both the combustor exit and the engine exit. At each location the above species were classified into one of four categories of decreasing importance, Priority I through IV, as follows: Combustor exit: Priority I species - SO3:SO2 ratio, SO3, SO2, and particulates; Priority II species: OH and O; Priority III species - NO and NO2; and Priority IV species - CO and CO2. For the Engine exit: Priority I species - SO3:SO2 ratio, SO3, SO2,H2SO4, and particulates; Priority II species: OH,HO2, H2O2, and O; Priority III species - NO, NO2, HONO, and HNO3; and Priority IV species - CO and CO2. Table I summarizes the anticipated concentration range of each of these species. For particulate matter, the quantities of interest are the number density, size distribution, and composition. In order to provide data for validating multidimensional reacting flow models, it would be desirable to make 2-D, time-resolved measurements of the concentrations of the above species and, 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 reactions that must be included in two- and three-dimensional modeling studies.

Radhakrishnan, Krishnan; Whitefield, Philip

1999-01-01

371

Theoretical and Laboratory Studies on the Interaction of Cosmic-Ray Particles with Interstellar Ices. III. Suprathermal Chemistry-induced Formation of Hydrocarbon Molecules in Solid Methane, (CH 4), Ethylene (C 2H 4), and Acetylene (C 2H 2)  

Microsoft Academic Search

Methane, ethylene, and acetylene ices are irradiated in a ultra high vacuum vessel at 10 K with 9.0 MeV alpha -particles and 7.3 MeV protons to elucidate mechanisms to form hydrocarbon molecules upon interaction of Galactic cosmic-ray particles with extraterrestrial, organic ices. Theoretical calculations focus on computer simulations of ion-induced collision cascades in irradiated targets. Our experimental and computational investigations

R. I. Kaiser; K. Roessler

1998-01-01

372

Combustion instability modeling and analysis  

SciTech Connect

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

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

1995-12-31

373

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

NASA Technical Reports Server (NTRS)

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

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

1983-01-01

374

Online and offline experimental techniques for polycyclic aromatic hydrocarbons recovery and measurement.  

PubMed

The implementation of techniques aimed at improving engine performance and reducing particulate matter (PM) pollutant emissions is strongly influenced by the limited understanding of the polycyclic aromatic hydrocarbons (PAH) formation chemistry, in combustion devices, that produces the PM emissions. New experimental results which examine the formation of multi-ring compounds are required. The present investigation focuses on two techniques for such an experimental examination by recovery of PAH compounds from a typical combustion oriented experimental apparatus. The online technique discussed constitutes an optimal solution but not always feasible approach. Nevertheless, a detailed description of a new online sampling system is provided which can serve as reference for future applications to different experimental set-ups. In comparison, an offline technique, which is sometimes more experimentally feasible but not necessarily optimal, has been studied in detail for the recovery of a variety of compounds with different properties, including naphthalene, biphenyl, and iodobenzene. The recovery results from both techniques were excellent with an error in the total carbon balance of around 10% for the online technique and an uncertainty in the measurement of the single species of around 7% for the offline technique. Although both techniques proved to be suitable for measurement of large PAH compounds, the online technique represents the optimal solution in view of the simplicity of the corresponding experimental procedure. On the other hand, the offline technique represents a valuable solution in those cases where the online technique cannot be implemented. PMID:22462939

Comandini, A; Malewicki, T; Brezinsky, K

2012-03-01

375

Online and offline experimental techniques for polycyclic aromatic hydrocarbons recovery and measurement  

NASA Astrophysics Data System (ADS)

The implementation of techniques aimed at improving engine performance and reducing particulate matter (PM) pollutant emissions is strongly influenced by the limited understanding of the polycyclic aromatic hydrocarbons (PAH) formation chemistry, in combustion devices, that produces the PM emissions. New experimental results which examine the formation of multi-ring compounds are required. The present investigation focuses on two techniques for such an experimental examination by recovery of PAH compounds from a typical combustion oriented experimental apparatus. The online technique discussed constitutes an optimal solution but not always feasible approach. Nevertheless, a detailed description of a new online sampling system is provided which can serve as reference for future applications to different experimental set-ups. In comparison, an offline technique, which is sometimes more experimentally feasible but not necessarily optimal, has been studied in detail for the recovery of a variety of compounds with different properties, including naphthalene, biphenyl, and iodobenzene. The recovery results from both techniques were excellent with an error in the total carbon balance of around 10% for the online technique and an uncertainty in the measurement of the single species of around 7% for the offline technique. Although both techniques proved to be suitable for measurement of large PAH compounds, the online technique represents the optimal solution in view of the simplicity of the corresponding experimental procedure. On the other hand, the offline technique represents a valuable solution in those cases where the online technique cannot be implemented.

Comandini, A.; Malewicki, T.; Brezinsky, K.

2012-03-01

376

The phase analysis of coal combustion ashes  

Microsoft Academic Search

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

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

1994-01-01

377

Nonadiabatic Processes Relevant to HEDMs and Atmospheric Chemistry.  

National Technical Information Service (NTIS)

Our research focuses on the electronic structure aspects of electronically non adiabatic processes relevant to the stability and combustion of high energy density materials (HEDMs) and atmospheric chemistry. Our funded research has focused on two problems...

D. R. Yarkony

2002-01-01

378

High temperature materials chemistry - IV. Volume 88-5  

Microsoft Academic Search

These proceedings collect papers given at a symposium on high temperature material chemistry. Topics include combustion kinetics, titanium nitrides, borides, composites, demetallization, evaporation, mineral matter in coal, vapor deposition, ion implantation, yttrium oxides, uranium oxides, and alloys.

Z. A. Munir; D. Cubicciotti; H. Tagawa

1988-01-01

379

Constant-Pressure Combustion Charts Including Effects of Diluent Addition  

NASA Technical Reports Server (NTRS)

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.

Turner, L Richard; Bogart, Donald

1949-01-01

380

Constant-pressure combustion charts including effects of diluent addition  

NASA Technical Reports Server (NTRS)

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.

Turner, L Richard; Bogart, Donald

1949-01-01

381

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

NASA Technical Reports Server (NTRS)

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 serve as a qualitative marker of flame temperature. All images were taken in the environment of actual engines during flight, using actual jet fuel. The results of the PLIF study led directly to the modification of a fuel injector.

Hicks, Yolanda Royce

1996-01-01

382

Quench Layer Contribution to Exhaust Hydrocarbons from a Spark-Ignited Engine  

Microsoft Academic Search

Hydrocarbons remaining in a wall quench layer have been proposed as a major source of hydrocarbon emissions in spark-ignited internal combustion engines (Daniel and Wentworth, 1962). Additional experiments using wall mounted sampling valves were subsequently carried out by Daniel (1967), Mller and von Watzdorf (1968), Weiss et al. (1979), and Henningsen and Qvale (1980). Our paper presents the results of

J. A. LORUSSO; E. W. KAISER; G. A. LAVOIE

1981-01-01

383

In-Cylinder Measurements of Wall Layer Hydrocarbons in a Spark Ignited Engine  

Microsoft Academic Search

The hydrocarbon emissions process for the conventional, spark ignited, IC engine has been studied experimentally using a rapid acting gas sampling valve mounted in the combustion chamber wall. The sampling valve was electrohydraulically actuated. Design of the valve specifically allowed sampling in the vicinity of the wall quench layer with minimum leakage and crevice contributions to the measured hydrocarbon concentrations.

J. A. Lorusso; E. W. Kaiser; G. A. Lavoie

1983-01-01

384

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

Microsoft Academic Search

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

Stephen M. Bowes III

1996-01-01

385

Sandia combustion research program: Annual report, 1987  

SciTech Connect

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

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

1988-01-01

386

Factors affecting pore water hydrocarbon concentrations in Puget Sound sediments  

NASA Astrophysics Data System (ADS)

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

Socha, Stephen B.; Carpenter, Roy

1987-05-01

387

Factors affecting pore water hydrocarbon concentrations in Puget Sound sediments  

SciTech Connect

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

Socha, S.B.; Carpenter, R.

1987-05-01

388

NASA Microgravity Combustion Science Program  

NASA Technical Reports Server (NTRS)

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 by gravity, allowing major strides in our understanding of combustion processes and in subsequent development of improved combustion devices leading to improved quality of life on Earth. Fire and/or explosion events aboard spacecraft could be devastating to international efforts to expand the human presence in space. Testing to date has shown that ignition and flame spread on fuel surfaces (e.g., paper, wire insulation) behave quite differently under partial gravity and microgravity conditions. In addition, fire signatures-i.e., heat release, smoke production, flame visibility, and radiation-are now known to be quite different in reduced gravity environments; this research has provided data to improve the effectiveness of fire prevention practices, smoke and fire detectors, and fire extinguishment systems. The more we can apply our scientific and technological understanding to potential fire behavior in microgravity and partial gravity, the more assurance can be given to those people whose lives depend on the environment aboard spacecraft or eventually on habitats on the Moon or Mars.

King, Merrill K.

1999-01-01

389

Photolytic processes for measurement of combustion heats of formation and reaction rates. Final report.  

National Technical Information Service (NTIS)

This project includes measurements of the kinetics, fluorescence spectra and thermochemistry of alkoxy radicals which are important species in the combustion of hydrocarbons. RO radicals were produced by the laser photolysis of RONO.

J. B. Halpern H. Okabe

1990-01-01

390

Synthesis, Purification, and Physical Properties of Seven Twelve-Carbon Hydrocarbons  

Microsoft Academic Search

As part of a program to determine accurately the heats of combustion of specialized fuels in the kerosene range, seven hydrocarbons, biphenyl, bicyclohexyl, cyclohexylbenzene, n-hexylbenzene, n-hexylcyclohexane, 1-cyclopentylheptane, and n-dodecane were synthesized or purified from commercial material. Physical constants were determined on the purified samples. These materials may have use as secondary standards for heat of combustion measurements.

Thomas W. Mears; Connie L; Edward L. Compere; Frank L. Howard

391

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

NASA Astrophysics Data System (ADS)

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

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

2009-11-01

392

Chemical Kinetic Models for HCCI and Diesel Combustion  

SciTech Connect

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

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

2008-10-30

393

Chemistry Notes.  

ERIC Educational Resources Information Center

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

School Science Review, 1981

1981-01-01

394

SUPRAMOLECULAR CHEMISTRY  

Microsoft Academic Search

the photoinitiated forma- tion of substituted tropy- lium salts from arylcyclo- heptatrienes bearing a leaving group such as the methoxy group. Two topics of supramolecular chemistry are studied in the Supramolecular Photo- chemistry group: host-guest complexes based on calixarenes and photoswitchable rotaxanes. - Newly designed calix(4)arenes, substituted with a different number of cycloheptatrienyl or tropylium functions at the upper rim

Hans-Werner Abraham

395

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

SciTech Connect

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.

Authors, Various

1981-05-01

396

A Study on the Effect of Stratified Mixture Formation on Combustion Characteristics in a Constant Volume Combustion Chamber  

NASA Astrophysics Data System (ADS)

It is well known that a lean burn engine caused by stratified mixture formation has many kinds of advantages to combustion characteristics, such as higher thermal efficiency and lower CO, NOx levels than conventional homogeneous mixture combustion. Although this combustion can achieve low fuel consumption, it produces much unburned hydrocarbon and soot because of inhomogeneity of the charge mixture in the combustion chamber. Therefore, it is necessary to investigate the effect of mixture formation on combustion characteristics in order to obtain the stable lean combustion. In this paper, fundamental studies for stratified combustion were carried out using a constant volume combustion chamber. The effect of mixture formation on the combustion characteristics in the chamber was examined experimentally. In addition, the effect of turbulence on stratified charge combustion process was observed by schlieren photography. From this study, as the swirl intensity increases, (Sv)max is rapidly enhanced and the period of combustion is shortened. We also find that the stratification degree can be quantified by using burning velocity and it was controlled by induced air pressure and turbulent intensity.

Lee, Kihyung; Lee, Changhee; Jeoung, Haeyoung

397

Chemical Kinetic Modeling of Biofuel Combustion  

NASA Astrophysics Data System (ADS)

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

Sarathy, Subram Maniam

398

Polycyclic Aromatic Hydrocarbons in Maternal and Cord Blood Plasma  

Microsoft Academic Search

Polycyclic aromatic hydrocarbons (PAH) come from incomplete combustion of organic materials, including tobacco smoke. Some PAH are known to be mutagenic and carcinogenic and of concern for the fetus when women smoke during pregnancy. Known consequences of smoking during pregnancy include low birth weight (LBW) and preterm (PT) delivery. This study was designed to measure concentrations of 3 PAH: anthracene

Paula G. Radmacher; Stephen W. Looney; Steven R. Myers

2010-01-01

399

Woodburning as a source of atmospheric polycyclic aromatic hydrocarbons  

Microsoft Academic Search

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

Diana J. Freeman; Frank C. R. Cattell

1990-01-01

400

Structure-biodegradability relationships of polycyclic aromatic hydrocarbons in soil  

Microsoft Academic Search

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

Ingeborg D. Bossert; Richard Bartha

1986-01-01

401

Electron-induced dissociation of hydrocarbon multilayers  

NASA Astrophysics Data System (ADS)

We have recently observed large cross sections ( ? = 1.8 10 -15 cm 2) for electron induced dissociation (EID) of physisorbed cyclohexane in multilayers on Pt(111) surfaces. This is a general phenomenon for hydrocarbon multilayers and for other physisorbed hydrocarbon species at monolayer or submonolayer coverages. While it is certainly not new to identify electron induced effects in adsorbed layers, the large EID cross sections reported here and their implications for physisorbed hydrocarbons is not generally appreciated. Two consequences of this chemistry are discussed. First, these EID cross sections are so large that serious artifacts in temperature programmed desorption (TPD) can be caused even in the short time it takes to perform a TPD experiment using a conventional quadrupole mass spectrometer (QMS) which can bombard the sample with electron fluxes in the ?A regime. This problem in TPD can be overcome by utilizing a biased grid between the sample and the QMS ionizer region to stop low energy electrons. However, the secondary electron emission inherent in many electron spectroscopies (XPS, UPS, AES, etc.) may cause similar effects that are difficult to eliminate. Secondly, the large difference in EID cross sections between physisorbed and chemisorbed species has the exciting consequence that well-defined, complex hydrocarbon surface intermediates, e.g., cyclohexyl, can be prepared cleanly on reactive metal surfaces for chemistry studies.

Xu, Chen; Koel, Bruce E.

402

Electron-induced dissociation of hydrocarbon multilayers  

NASA Astrophysics Data System (ADS)

We have recently observed large cross sections ( ? = 1.8 10 -15 cm 2) for electron induced dissociation (EID) of physisorbed cyclohexane in multilayers on Pt(111) surfaces. This is a general phenomenon for hydrocarbon multilayers and for other physisorbed hydrocarbon species at monolayer or submonolayer coverages. While it is certainly not new to identify electron induced effects in adsorbed layers, the large EID cross sections reported here and their implications for physisorbed hydrocarbons is not generally appreciated. Two consequences of this chemistry are discussed. First, these EID cross sections are so large that serious artifacts in temperature programmed desorption (TPD) can be caused even in the short time it takes to perform a TPD experiment using a conventional quadrupole mass spectrometer (QMS) which can bombard the sample with electron fluxes in the ?A regime. This problem in TPD can be overcome by utilizing a biased grid between the sample and the QMS ionizer region to stop low energy electrons. However, the secondary electron emission inherent in many electron spectroscopies (XPS, UPS, AES, etc.) may cause similar effects that are difficult to eliminate. Secondly, the large difference in EID cross sections between physisorbed and chemisorbed species has the exciting consequence that well-defined, complex hydrocarbon surface intermediates, e.g., cyclohexyl, can be prepared cleanly on reactive metal surfaces for chemistry studies.

Xu, Chen; Koel, Bruce E.

1993-07-01

403

Combustibility of titanium powders  

NASA Technical Reports Server (NTRS)

The combustion of compact samples was studied; the mechanism of autoignition is defined. Several studies are made of the combustibility of titanium using 50 samples. The data provide a clear idea of the combustibility of titanium powders.

Popov, Ye. I.; Poyarkov, V. G.; Finayev, Yu. A.

1989-01-01

404

A Novel Solar Thermal Cycle with Chemical Looping Combustion  

Microsoft Academic Search

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

Hui Hong; Hongguang Jin

2005-01-01

405

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

SciTech Connect

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

Ma, X.; Schobert, H.H.

2000-02-10

406

Navier-Stokes simulation of transient fluid dynamics and initiation of combustion in the ram accelerator  

NASA Astrophysics Data System (ADS)

Computational fluid dynamics solutions of the full Navier-Stokes equations have been used to numerically simulate the reacting in-bore flowfield for the ram accelerator projectile propulsion system. In this system, a projectile is injected at supersonic velocity into a stationary tube filled with a pressurized mixture of hydrocarbon, oxidizer, and inert gases. The natural shock system generated around the projectile in conjunction with a pusher sabot initiates combustion of the mixture. Combustion takes place on the projectile surface and in the wake. This energy release process which travels with the projectile also generates high pressures and imparts thrust to the projectile. Whereas numerical solution of governing equations utilizing finite-rate chemical kinetics has been reported previously, this paper investigates the utility of the equilibrium chemistry assumption for this flowfield. Results show that these simulations can numerically reproduce several modes of accelerator operation both using a perforated and a solid pusher sabot for the projectile, and including those modes at and beyond the Chapman-Jouget detonation velocity of the mixture.

Nusca, Michael J.

1992-10-01

407

Identification and Atmospheric Reactions of Polar Products of Selected Aromatic Hydrocarbons.  

National Technical Information Service (NTIS)

During this experimental program, we have used the facilities and expertise available at the Air Pollution Research Center, University of California, Riverside, to investigate the atmospheric chemistry of selected aromatic hydrocarbons found in California...

2006-01-01

408

Circumstellar chemistry  

NASA Technical Reports Server (NTRS)

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.

Glassgold, Alfred E.; Huggins, Patrick J.

1987-01-01

409

Radioanalytical Chemistry  

NSDL National Science Digital Library

This website provides a course on the use of radionuclides in analytical chemistry. Types of radioactive decay are discussed as well as the techniques of scintillation counting, neutron activation analysis, and gamma spectroscopy.

Hardy, James K.

2010-07-01

410

Chemistry Notes.  

ERIC Educational Resources Information Center

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

School Science Review, 1980

1980-01-01

411

Chemistry Notes  

ERIC Educational Resources Information Center

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

School Science Review, 1973

1973-01-01

412

Catalytic Chemistry.  

ERIC Educational Resources Information Center

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

Borer, Londa; And Others

1996-01-01

413

Organoleptic Chemistry.  

ERIC Educational Resources Information Center

Discusses how the concept of organoleptic chemistry permeates every modern chemical experiment. Six approaches for developing organoleptic attitudes which are crucial to the experimental aspects are also presented. (HM)

Slabaugh, W. H.

1980-01-01

414

Precolumbian Chemistry.  

ERIC Educational Resources Information Center

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)

Robinson, Janet Bond

1995-01-01

415

Nuclear Chemistry.  

ERIC Educational Resources Information Center

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

Chemical and Engineering News, 1979

1979-01-01

416

Urine chemistry  

MedlinePLUS

Chemistry - urine ... For this test, a clean-catch (midstream) urine sample is needed. For more information, see: Urine collection - clean catch . Some tests require that you collect all of your urine for 24 ...

417

Chemistry Notes.  

ERIC Educational Resources Information Center

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

School Science Review, 1981

1981-01-01

418

Near-threshold absolute photoionization cross-sections of some reaction intermediates in combustion  

NASA Astrophysics Data System (ADS)

The use of photoionization mass spectrometry for the development of quantitative kinetic models for the complex combustion chemistry of both conventional hydrocarbon fuels and oxygenated biofuels requires near-threshold measurements of absolute photoionization cross-sections for numerous reaction intermediates. Near-threshold absolute cross-sections for molecular and dissociative photoionization for 20 stable reaction intermediates (methane, ethane, propane, n-butane, cyclopropane, methylcyclopentane, 1-butene, cis-2-butene, isobutene, 1-pentene, cyclohexene, 3,3-dimethyl-1-butene, 1,3-hexadiene, 1,3-cyclohexadiene, methyl acetate, ethyl acetate, tetrahydrofuran, propanal, 1-butyne, 2-butyne) are presented. Previously measured total photoionization cross-sections for 9 of these molecules are in good agreement with the present results. The measurements are performed with photoionization mass spectrometry (PIMS) using a monochromated VUV synchrotron light source with an energy resolution of 40 meV (fwhm) comparable to that used for flame-sampling molecular beam PIMS studies of flame chemistry and reaction kinetics.

Wang, Juan; Yang, Bin; Cool, Terrill A.; Hansen, Nils; Kasper, Tina

2008-02-01

419

Characterization of soot aerosol produced from combustion of propane in a shock tube  

Microsoft Academic Search

The knowledge of yields and properties of soot from combustion of hydrocarbon fuels is crucial for accurate evaluation of the impacts of primary aerosols on air quality and climate. This study presents measurements of soot generated from combustion of propane in a shock tube, using independently adjustable fuel equivalence ratio (?), temperature, and pressure. The characterization of soot yields inside

Alexei F. Khalizov; Brian Hogan; Chong Qiu; Eric L. Petersen; Renyi Zhang

2012-01-01

420

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

SciTech Connect

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.

Kass, Michael D [Oak Ridge, TN

2007-07-24

421

Stratospheric chemistry  

SciTech Connect

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

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

1991-01-01

422

Chemistry Tutorials  

NSDL National Science Digital Library

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

423

Method and apparatus for secondary and tertiary recovery of hydrocarbons  

SciTech Connect

This patent describes an apparatus for secondary and tertiary recovery of hydrocarbons from oil fields comprising: a. a bipropellant generator capable of producing exhaust gases at supercritical pressures and temperatures; b. transport means for carrying the exhaust gases into a well bore, at least a portion of the well bore extending into a hydrocarbon bearing formation from which hydrocarbons are to be recovered; c. means for introducing water into the transport means; and d. a water cooling jacket extending into at least the upper portion of the well bore, the center of the cooling jacket receiving the exhaust gases from the transport means, means being provided for the introduction of chemical additives through a portion of the cooling jacket. A process is described for secondary and tertiary recovery of hydrocarbons from geological formations comprising: a. providing a well bore extending at least into the strata of the geologic formation containing the hydrocarbons to be recovered; b. providing at least the upper portion of the well bore with a cooling jacket, the cooling jacket being provided with a central, open portion; c. generating gases at supercritical temperatures and pressures; d. introducing water into the supercritical gases to form steam; e. forcing the mixture of supercritical combustion gases and steam through the central open portion of the cooling jacket and the well bore into the hydrocarbon strata; and f. adding chemical additives to the mixture of combustion gases and steam below the cooling jacket.

Rivas, N.; Beichel, R.

1987-07-07

424

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...

425

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...

426

Spectroscopy, Kinetics, and Dynamics of Combustion Radicals  

SciTech Connect

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.

Nesbitt, David J. [Research/Professor

2013-08-06

427

Numerical Simulation of Single Aluminum Particle Combustion (Review)  

Microsoft Academic Search

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

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

2005-01-01

428

A laboratory scale supersonic combustive flow system  

SciTech Connect

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

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

1995-02-01

429

Ethylene oxidation chemistry in a well-stirred reactor  

SciTech Connect

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

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

1994-09-01

430

An experimental study on high temperature and low oxygen air combustion  

Microsoft Academic Search

High temperature preheated and diluted air combustion has been confirmed as the technology, mainly applied to industrial furnaces\\u000a and kilns, for realizing higher thermal efficiency and lower emissions. The purpose of this study was to investigate fundamental\\u000a aspects of the above-mentioned combustion experimentally and to compare with those in ordinary hydrocarbon combustion with\\u000a room temperature air. The test items were

Dae Hun Chung; Jae Bok Yang; Dong Sun Noh; Won Bae Kim

1999-01-01

431

An experimental study on high temperature and low oxygen air combustion  

Microsoft Academic Search

High temperature preheated and diluted air combustion has been confirmed as the technology, mainly applied to industrial furnaces\\u000a and kilns, to realize higher thermal efficiency and lower emissions. The purpose of this study was to investigate fundamental\\u000a aspects of the above-mentioned combustion experimentally and to compare with those in ordinary hydrocarbon combustion with\\u000a room temperature air. The test items were

W. B. Kim; D. H. Chung; J. B. Yang; D. S. Noh

2000-01-01

432

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

DOEpatents

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.

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

1998-07-14

433

Computational Chemistry for Chemistry Educators  

NSDL National Science Digital Library

In this paper we describe an ongoing project where the goal is to develop competence and confidence among chemistry faculty so they are able to utilize computational chemistry as an effective teaching tool. Advances in hardware and software have made research-grade tools readily available to the academic community. Training is required so that faculty can take full advantage of this technology, begin to transform the educational landscape, and attract more students to the study of science.

Sendlinger, Shawn C.; Metz, Clyde R.

434

Chemistry of Aviation Fuels  

NASA Technical Reports Server (NTRS)

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.

Knepper, Bryan; Hwang, Soon Muk; DeWitt, Kenneth J.

2004-01-01

435

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

SciTech Connect

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

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

2000-11-29

436

Coal combustion science  

SciTech Connect

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

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

1990-11-01

437

HC quench layer formation in combustion processes. Technical progress report, May-November 1980  

SciTech Connect

Objective is to understand wall quenching and other processes responsible for surface generated hydrocarbons in combustion under engine-like conditions. The study concerns the effects of turbulence on the evolution of hydrocarbons. The work is divided into three tasks: (1) combustion bomb experiments to measure the effect of turbulence on the chemical species near the cold surface; (2) combustion bomb experiments, using a similar turbulence generating device, to fully characterize the flow and turbulence in the vicinity of the quenching surface; and (3) an analytical study to characterize fluid mechanical scales of interest in the boundary layer and to find an analytical solution to describe the evolution of the layer.

Lavoie, G A

1980-12-01

438

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)

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 each investigation. When possible, similar investigations will be flown at the same time to increase the use of common hardware and diagnostics. To further reduce the amount of new hardware that needs to be supplied for each investigation, multi-user chamber inserts, such as MDCA, are being designed. The inserts will contain, to the greatest extent possible, the hardware needed for a class of investigations. Two inserts will support the combustion of solid fuel samples in different sample configurations. Low speed flows over their surface will be obtained by the use of a small flow tunnel. The MDCA insert will support the combustion of droplets. Freely deployed or tethered single droplets, moving droplets, and droplet arrays will be investigated. A third insert will support laminar and turbulent gaseous combustion experiments. Each insert will be customized by the addition or removal of small amounts of hardware, such as sample holders or burners, for each experiment. The MDCA contains the hardware and software required to conduct unique droplet combustion experiments in space. It consists of a Chamber Insert Assembly, an Avionics Package, and a suite of diagnostics. It's modular approach permits on-orbit changes for accommodating different fuels, fuel flow rates, soot sampling mechanisms, and varying droplet support and translation mechanisms to accommodate multiple investigations. Unique diagnostic measurement capabilities for each investigation are also provided. Additional hardware provided by the CIR facility includes the structural support, a combustion chamber, utilities for the avionics and diagnostic packages, and the fuel mixing capability for PI specific combustion chamber environments. Common diagnostics provided by the CIR will also be utilized by the MDCA. Single combustible fuel droplets of varying sizes, freely deployed or supported by a tether are planned for study using the MDCA. Such research supports how liquid-fuel-droplets ignite, spread, and extinguish under quiescent microgravity conditions. This understanding will help us develop more

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

2002-01-01

439

Fuel Flexibility in Combustion  

SciTech Connect

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

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

2001-11-06

440

Kinetic models of combustion of kerosene and its components  

Microsoft Academic Search

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

G. Ya. Gerasimov; S. A. Losev

2005-01-01

441

Chemical kinetic modelling of hydrocarbon ignition  

SciTech Connect

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

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

1995-08-25

442

PDF Modeling of Turbulent Lean Premixed Combustion  

SciTech Connect

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 Laboratorys on-going research in Assessment of Turbo-Chemistry Models for Gas Turbine Combustion Emissions under the RDS contract DE-AC26-04NT41817.

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

2007-10-01

443

Modeling complex chemical effects in turbulent nonpremixed combustion  

NASA Technical Reports Server (NTRS)

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 equations.

Smith, Nigel S. A.

1995-01-01

444

Chemistry & Industry  

NSDL National Science Digital Library

Chemistry and Industry Magazine, a bimonthly product of the Society of Chemical Industry, provides selected full-text articles from the print magazine in the areas of news, commentary, features, latest results from chemical literature, and highlights from the latest European patents. In addition, there is a searchable and browsable archive of past issues, a daily news section, and searchable jobs and meetings databases. The Society of Chemical Industry is "an international association of about 6000 members aimed at furthering applied chemistry." One of the highlights of its web site is its publication section, where, under "electronic publications," readers can find updated daily news, jobs and meetings listings on chemistry, pharmaceuticals, biotechnology, and the environment.

1997-01-01

445

Kitchen Chemistry  

NSDL National Science Digital Library

There is a great deal of chemistry going on in every kitchen, even though most cooks may not be cognizant of the various interactions going on in the pot, wok, or oven. MIT's popular OpenCourseWare Initiative has recently made the contents of Dr. Patricia Christie's course on kitchen chemistry available on this site. Visitors to the site can download the syllabus, take in some assigned readings (and recipes), and look over the assignments. The assignments include investigations that involve emulsifiers, ice cream, peer teaching, and pancakes, among other things. The site also includes links to helpful readings, such as those on chocolate, the health benefits of capsicum, and the world of gluten. For people who wish to bring back the frayed connective tissue between chemistry and the culinary arts, this site is absolutely essential.

Christie, Patricia

2006-01-01

446

Chemistry Experiments  

NASA Technical Reports Server (NTRS)

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.

Brasseur, Guy;