Critical Evaluation of Thermochemical Properties of C1–C4 Species: Updated Group-Contributions to Estimate Thermochemical Properties

Burke, Sinéad M.; Simmie, John M.; Curran, Henry J.

doi:10.1063/1.4902535

Cited by 99 publications

(77 citation statements)

References 113 publications

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“…22 Due to improved computational methods for calculation of thermochemical properties and a growing amount of literature data, a thorough literature review of thermochemical properties was undertaken for C 1 -C 4 alkanes, alkenes, alcohols, hydroperoxides, alcoholic hydroperoxides, and their associated radicals. 23 A variety of sources, including high level ab initio studies, experimental studies, online databases, and review studies has led to updated THERM group values which have been used to update the thermochemistry of the following classes of C 5 species: fuel (RH), fuel radicals (Ṙ), olefins, alkyl hydroperoxides (RO 2 H), alkyl-peroxyl radicals (R ̇2 ), hydroperoxyl alkyl radicals ( ̇O OH), cyclic ethers, hydroperoxylalkyl-peroxyl radicals ( ̇2 QOOH) and carbonyl-hydroperoxides, as well as any species produced through pathways which have been added to the mechanisms, which will be discussed in detail later. …”

Section: Thermochemistrymentioning

confidence: 99%

Revisiting the Kinetics and Thermodynamics of the Low-Temperature Oxidation Pathways of Alkanes: A Case Study of the Three Pentane Isomers

et al. 2015

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This paper describes our developing understanding of low-temperature oxidation kinetics. We have investigated the ignition of the three pentane isomers in a rapid compression machine over a wide range of temperatures and pressures, including conditions of negative temperature coefficient behavior. The pentane isomers are small alkanes, yet have structures that are complex enough to allow for the application of their kinetic and thermochemical rules to larger molecules. Updates to the thermochemistry of the species important in the low-temperature oxidation of hydrocarbons have been made based on a thorough literature review. An evaluation of recent quantum-chemically derived rate coefficients from the literature pertinent to important low-temperature oxidation reaction classes has been performed, and new rate rules are recommended for these classes. Several reaction classes have also been included to determine their importance with regard to simulation results, and we have found that they should be included when developing future chemical kinetic mechanisms. A comparison of the model simulations with pressure-time histories from experiments in a rapid compression machine shows very good agreement for both ignition delay time and pressure rise for both the firstand second-stage ignition events. We show that revisions to both the thermochemistry and the kinetics are required in order to replicate experiments well. A broader validation of the models with ignition delay times from shock tubes and a rapid compression machine is presented in an accompanying paper. The results of this study enhance our understanding of the combustion of straight-and branched-chained alkanes.

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Section: Thermochemistrymentioning

confidence: 99%

Revisiting the Kinetics and Thermodynamics of the Low-Temperature Oxidation Pathways of Alkanes: A Case Study of the Three Pentane Isomers

et al. 2015

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“…The important thermodynamic parameters are estimated using the group additivity method employed by Benson [46] with updated group values by Burke et al [47] and utilized in the program developed by Ritter and Bozzelli [48]. During these developments, the mechanism has been validated against numerous experimental conditions and targets.…”

Section: Chemical Kinetic Mechanism Developmentmentioning

confidence: 99%

A comprehensive experimental and modeling study of isobutene oxidation

Zhou

O'Connor

et al. 2016

Combustion and Flame

297

189

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Isobutene is an important intermediate in the pyrolysis and oxidation of higher-order branched alkanes, and it is also a component of commercial gasolines. To better understand its combustion characteristics, a series of ignition delay time (IDT) and laminar flame speed (LFS) measurements have been performed. In addition, flow reactor speciation data recorded for the pyrolysis and oxidation of isobutene is also reported. Predictions of an updated kinetic model described herein are compared with each of these data sets, as well as with existing jet-stirred reactor (JSR) species measurements.IDTs of isobutene oxidation were measured in four different shock tubes and in two rapid compression machines (RCMs) under conditions of relevance to practical combustors. The combination of shock tube and RCM data greatly expands the range of available validation data for isobutene oxidation models to pressures of 50 atm and temperatures in the range 666-1715 K. Isobutene flame speeds were measured experimentally at 1 atm and at unburned gas temperatures of 298-398 K over a wide range of equivalence ratios. For the flame speed results, there was good agreement between different facilities and the current model in the fuel-rich region.Ab initio chemical kinetics calculations were carried out to calculate rate constants for important reactions such as H-atom abstraction by hydroxyl and hydroperoxyl radicals and the decomposition of 2-methylallyl radicals.A comprehensive chemical kinetic mechanism has been developed to describe the combustion of isobutene and is validated by comparison to the presently considered experimental measurements. Important reactions, highlighted via flux and sensitivity analyses, include: (a) hydrogen atom abstraction from isobutene by hydroxyl and hydroperoxyl radicals, and molecular oxygen; (b) radical-radical recombination reactions, including 2-methylallyl radical self-recombination, the recombination of 2-methylallyl radicals with hydroperoxyl radicals; and the recombination of 2-methylallyl radicals with methyl radicals; (c) addition reactions, including hydrogen atom and 2 hydroxyl radical addition to isobutene; and (d) 2-methylallyl radical decomposition reactions. The current mechanism accurately predicts the IDT and LFS measurements presented in this study, as well as the JSR and flow reactor speciation data already available in the literature.The differences in low-temperature chemistry between alkanes and alkenes are also highlighted in this work. In normal alkanes, the fuel radical Ṙ adds to molecular oxygen forming alkylperoxyl (RȮ 2 ) radicals followed by isomerization and chain branching reactions which promote low-temperature fuel reactivity. However, in alkenes, because of the relatively shallow well (~20 kcal mol -1 ) for RȮ 2 formation compared to ~35 kcal mol -1 in alkanes, the Ṙ + O 2 ⇌ RȮ 2 equilibrium lies more to the left favoring Ṙ + O 2 rather than RȮ 2 radical stabilization. Based on this work, and related studies of allylic systems, it is apparent that reactivity fo...

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“…radical) and OO/C/H group values from Burke et al 15 are used to recalculate the thermodynamic data of all species in the 2-methylhexane kinetic mechanism. Optical isomers and the effect of the non-next-nearest neighbor interactions (NNI), especially gauche interactions [36][37] were taken into account.…”

Section: Updates Of Thermochemical Datamentioning

confidence: 99%

“…Bugler et al 5 revisited the chemical kinetic models of the pentane isomers originally developed by Healy et al 9 . In their work, they investigated the effect of implementing thermodynamic and reaction rate updates [10][11][12][13][14][15] , as well as the addition of alternative OOQOOH isomerization pathways, on the combustion properties of pentane isomers. Finally, n-hexane sub-mechanism in Curran et al's 8 heptane model was updated by Zhang et al 6 .…”

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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Critical Evaluation of Thermochemical Properties of C1–C4 Species: Updated Group-Contributions to Estimate Thermochemical Properties

Cited by 99 publications

References 113 publications

Revisiting the Kinetics and Thermodynamics of the Low-Temperature Oxidation Pathways of Alkanes: A Case Study of the Three Pentane Isomers

Revisiting the Kinetics and Thermodynamics of the Low-Temperature Oxidation Pathways of Alkanes: A Case Study of the Three Pentane Isomers

A comprehensive experimental and modeling study of isobutene oxidation

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

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