Chemical kinetic modeling study of shock tube ignition of heptane isomers

Westbrook, Charles K.; Pitz, William J.; Curran, Henry J.; Boercker, Janice; Kunrath, E

doi:10.1002/kin.10020

Cited by 77 publications

(59 citation statements)

References 27 publications

(46 reference statements)

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“…This agrees with past shock tube ignition delay experiments of Smith et al [31] and computed results of Westbrook et al [8,9] that showed that the ignition delay times for all of the heptane isomers, whose octane numbers range from 0 to 112, have nearly identical ignition delay times at high temperatures. The differences in ON for these isomers do not produce different ignition delay times at high temperatures.…”

Section: Primary Reference Fuel Mechanism Calculationssupporting

confidence: 91%

“…Selection of these two pairs of specific fuels, which are termed "Primary Reference Fuels" or PRFs, reflects the fact that diesel fuels are typically much heavier than gasolines, with hydrocarbon molecules correspondingly larger in diesel fuels. Thus the PRF components assigned to diesel fuel are both C 16 molecules, relecting the average carbon number and density of diesel fuel, while the PRF components for gasoline are a C 7 and a C 8 hydrocarbon. Both scales are similar in that each has a very easily ignited PRF n-alkane molecule, n-heptane (n-C 7 H 16 ) in the case of gasoline and n-hexadecane (n-C 16 H 34 , n-cetane) in the case of diesel fuel, and each has a highly branched iso-alkane component that is difficult to ignite, specifically iso-octane (2,2,4-trimethyl pentane, i-C 8 H 18 ) for gasoline and iso-cetane an ON of 100, while n-heptane has an ON equal to zero.…”

mentioning

confidence: 99%

“…Development of detailed chemical kinetic reaction mechanisms using the same reaction pathway and rate classes have provided kinetic tools for ignition and combustion studies of many other fuels [4][5][6][7][8][9][10][11][12] to study the role of fuel molecular structure on hydrocarbon ignition, and they provided a starting point to development of more general surrogate fuels for gasoline in SI engines [13] and diesel fuel in diesel engines [14].…”

mentioning

confidence: 99%

See 2 more Smart Citations

Detailed chemical kinetic reaction mechanisms for primary reference fuels for diesel cetane number and spark-ignition octane number

Westbrook

Pitz

Mehl

et al. 2011

Proceedings of the Combustion Institute

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Section: Primary Reference Fuel Mechanism Calculationssupporting

confidence: 91%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Detailed chemical kinetic reaction mechanisms for primary reference fuels for diesel cetane number and spark-ignition octane number

Westbrook

Pitz

Mehl

et al. 2011

Proceedings of the Combustion Institute

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“…The high-temperature mechanism for 2-methylhexane oxidation was initially proposed by Westbrook et al 17 as part of an experimental and modeling study on the heptane isomers. Later, Sarathy et al 18 updated this mechanism and added low-temperature oxidation pathways based on Curran et al's models for n-heptane and iso-octane 8,19 .…”

Section: Introductionmentioning

confidence: 99%

Modeling Ignition of a Heptane Isomer: Improved Thermodynamics, Reaction Pathways, Kinetics, and Rate Rule Optimizations for 2-Methylhexane

et al. 2016

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Accurate chemical kinetic combustion models of lightly branched alkanes (e.g., 2-methylalkanes) are important to investigate the combustion behavior of real fuels. Improving the fidelity of existing kinetic models is a necessity, as new experiments and advanced theories show inaccuracies in certain portions of the models. This study focuses on updating thermodynamic data and the kinetic reaction mechanism for a gasoline surrogate component, 2-methylhexane, 2 based on recently published thermodynamic group values and rate rules derived from quantum calculations and experiments. Alternative pathways for the isomerization of peroxyalkylhydroperoxide (OOQOOH) radicals are also investigated. The effects of these updates are compared against new high-pressure shock tube and rapid compression machine ignition delay measurements. It is shown that rate constant modifications are required to improve agreement between kinetic modeling simulations and experimental data. We further demonstrate the ability to optimize the kinetic model using both manual and automated techniques for rate parameter tunings to improve agreement with the measured ignition delay time data. Finally, additional low temperature chain branching reaction pathways are shown to improve the model's performance.The present approach to model development provides better performance across extended operating conditions while also strengthening the fundamental basis of the model.

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“…In a rapid compression machine ignition study of the heptane isomers (φ = 1, P = 15 atm, 650 K to 950 K), Silke et al [21] showed that di-methylated heptane isomers exhibit lower reactivity when compared to mono-methylated and normal heptane isomers. In a series of comprehensive kinetic modeling studies on the autoignition of heptane isomers, Westbrook et al [22,23] also showed that the reactivity of di-methylated heptane isomers was lower than that of mono-methylated and normal heptane isomers at low and intermediate temperatures; however, at higher temperatures, their model predicted that all heptane isomers display the same ignition characteristics, which was later confirmed experimentally by Smith et al [5]. Not surprisingly, the aforementioned studies showed that the ignition behavior of heptane isomers in the negative temperature coefficient (NTC) region correlates with the research octane number (RON) of the fuel, which was also shown by Morley [24].…”

Section: Introductionmentioning

confidence: 99%

A comprehensive combustion chemistry study of 2,5-dimethylhexane

Sarathy

Javed

Karsenty

et al. 2014

Combustion and Flame

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Iso-paraffinic molecular structures larger than seven carbon atoms in chain length are commonly found in conventional petroleum, Fischer-Tropsch (FT), and other alternative hydrocarbon fuels, but little research has been done on their combustion behavior. Recent studies have focused on either mono-methylated alkanes and/or highly branched compounds (e.g., 2,2,4-trimethylpentane). In order to better understand the combustion characteristics of real fuels, this study presents new experimental data for the oxidation of 2,5-dimethylhexane under a wide variety of temperature, pressure, and equivalence ratio conditions. This new dataset includes jet stirred reactor speciation, shock tube ignition delay, and rapid compression machine ignition delay, which builds upon recently published data for counterflow flame ignition, extinction, and speciation profiles. The low and high temperature oxidation of 2,5-dimethylhexane has been modeled using a comprehensive chemical kinetic model developed using established reaction rate rules. The agreement between the model and data is presented, along with suggestions for improving model predictions. The importance of propene chemistry is highlighted as critical for correct prediction of high temperature ignition delay. The oxidation behavior of 2,5-dimethylhexane is also compared with oxidation behavior of other linear and branched octane isomers, in order to determine the effects of the number of methyl branches on combustion properties. Both experimental data and model predictions indicate that increasing the level of branching decreases fuel reactivity at low and intermediate temperatures. The model is used to elucidate the structural features and reaction pathways responsible for inhibiting the reactivity of 2,5-dimethylhexane. FUEL or CNF, Sarathy et al. submitted July 2013Introduction Detailed chemical kinetic models for transportation fuels have reached a level of fidelity where accurate predictions can be made of combustion phenomenon relevant to the operation of practical devices. Schofield [1] states that these large scale models are adequate as engineering tools for studying the combustion of new fuel molecules. A recent review paper by Pitz and Mueller [2] describing the development of diesel surrogate fuel models concluded that major research gaps remain in modeling high molecular weight (i.e., C 8 and greater) aromatics, alkyl aromatics, cyclo-alkanes, and lightly branched iso-alkanes. The present study is concerned with the combustion of branched alkanes, specifically 2,5-dimethylhexane, which has been reported as a component of petroleum combustion exhaust, smog, and tobacco smoke [3]. Branched alkanes are important components of conventional diesel and jet fuels derived from petroleum [2,4]; synthetic Fischer-Tropsch diesel and jet fuels derived from coal, natural gas, and/or biomass [5,6]; and renewable diesel and jet fuels derived from thermochemical treatment of bio-derived fats and oils (e.g., hydrotreated renewable jet (HRJ) fuels) [7,8]. Detailed com...

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Chemical kinetic modeling study of shock tube ignition of heptane isomers

Cited by 77 publications

References 27 publications

Detailed chemical kinetic reaction mechanisms for primary reference fuels for diesel cetane number and spark-ignition octane number

Detailed chemical kinetic reaction mechanisms for primary reference fuels for diesel cetane number and spark-ignition octane number

Modeling Ignition of a Heptane Isomer: Improved Thermodynamics, Reaction Pathways, Kinetics, and Rate Rule Optimizations for 2-Methylhexane

A comprehensive combustion chemistry study of 2,5-dimethylhexane

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