n-Heptane cool flame chemistry: Unraveling intermediate species measured in a stirred reactor and motored engine

Wang, Zhandong; Chen, Bingjie; Moshammer, Kai; Popolan-Vaida, Denisia M.; Sioud, Salim; Shankar, Vijai Shankar Bhavani; Vuilleumier, David; Tao, Tao; Ruwe, Lena; Bräuer, Eike; Hansen, Nils; Dagaut, Philippe; Kohse‐Höinghaus, Katharina; Raji, Misjudeen; Sarathy, S. Mani

doi:10.1016/j.combustflame.2017.09.003

Cited by 67 publications

(69 citation statements)

References 92 publications

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“…Note that further additions to molecular oxygen are possible, evidence of which were detected in recent work performed by Wang et al [199], [200] at Lawrence Berkeley National Laboratory/Sandia National Laboratory.…”

Section: Low Temperature Chemistrymentioning

confidence: 77%

Developing detailed chemical kinetic mechanisms for fuel combustion

Curran

2019

Proceedings of the Combustion Institute

243

153

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This paper discusses a brief history of chemical kinetic modeling, with some emphasis on the development of chemical kinetic mechanisms describing fuel oxidation. At high temperatures, the important reactions tend to be those associated with the H2/O2 and C1-C2 sub-mechanisms, particularly for non-aromatic fuels. At low temperatures, and for aromatic fuels, the reactions that dominate and control the reaction kinetics are those associated with the parent fuel and its daughter radicals. Strategies used to develop and optimize chemical kinetic mechanisms are discussed and some reference is made to lumped and reduced mechanisms. The importance of accurate thermodynamic parameters for the species involved is also highlighted, as is the littlestudied importance of collider efficiencies of different third bodies involved in pressuredependent reactions.

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Section: Low Temperature Chemistrymentioning

confidence: 77%

Developing detailed chemical kinetic mechanisms for fuel combustion

Curran

2019

Proceedings of the Combustion Institute

243

153

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“…Briefly, hydrocarbon auto-ignition at high temperatures is governed by reactions between atomic hydrogen with molecular oxygen, while hydrogen peroxide (H2O2) decomposition drives auto-ignition at intermediate temperatures. Complex low-temperature termination, propagation, and branching pathways forming alkenes, cyclic ethers, and ketohydroperoxides (KHP) [9,10], respectively, control heat release rate, raise system temperature, and advance formation and decomposition of H2O2. The chemical kinetics of low-temperature oxidation [11] is strongly related to fuel molecular structure, and can be linked to interesting combustion phenomena such as cool flames [12], negative temperature coefficient (NTC) behavior [13], and fuel anti-knock quality (i.e., octane numbers) [14].…”

Section: Introductionmentioning

confidence: 99%

Three-stage heat release in n-heptane auto-ignition

Sarathy

Tingas

Nasir

et al. 2019

Proceedings of the Combustion Institute

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Colloquium: REACTION KINETICS / INTERNAL COMBUSTION ENGINES Word Count (Method 1): The total word count (exclusive of title page, abstract) is: 5793 words Word Count (Performed from automatic counting function in MS Word plus References/Tables/Equations/ Figures) Abstract: 235 words, not included in word count Equations: 0 words (0 equations, single column) Figures: 1030 words (4 figures with captions) 3 single 50(+10) 132 4 double 52(+10) 273 Captions 116 Total: 6055 words Supplemental Materials: One supplemental material is available. AbstractMulti-stage heat release is an important feature of hydrocarbon auto-ignition that influences engine operation. This work presents findings of previously unreported three-stage heat release in the autoignition of n-heptane/air mixtures at lean equivalence ratios and high pressures. Detailed homogenous gas-phase chemical kinetic simulations were utilized to identify conditions where two-stage and threestage heat release exist. Temperature and heat release profiles of lean n-heptane/air auto-ignition display three distinct stages of heat release, which is notably different than two-stage heat release typically reported for stoichiometric fuel/air mixtures. Concentration profiles of key radicals (HO2 and OH) and intermediate/product species (CO and CO2) also display unique behavior in the lean autoignition case. Rapid compression machine measurements were performed at a lean equivalence ratio to confirm the existence of three-stage heat release in experiments. Laser diagnostic measurements of CO concentrations in the RCM indicate similar concentration-time profiles as those predicted by kinetic modeling. Computational singular perturbation was then used to identify key reactions and species contributing to explosive time scales at various points of the three-stage ignition process.Comparisons with two-stage ignition at stoichiometric conditions indicate that thermal runaway at the second stage of heat release is inhibited under lean conditions. H+O2 chain branching and CO oxidation reactions drive high-temperature heat release under stoichiometric conditions, but these reactions are suppressed by H, OH, and HO2 radical termination reactions at lean conditions, leading to a distinct third stage of heat release.

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“…However, only Miyoshi 17 considered the rates where the peroxy is positioned at a tertiary site, and none of these studies investigated the effect of chirality on the calculated rates. Previous work has shown that the competition between standard α-H isomerization reactions and alternative isomerizations determines if molecules can undergo extensive auto-oxidation leading to highly oxygenated intermediates 1,[21][22][23][24] .…”

Section: Introductionmentioning

confidence: 99%

High-Pressure Limit Rate Rules for α-H Isomerization of Hydroperoxyalkylperoxy Radicals

et al. 2018

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Hydroperoxyalkylperoxy (OOQOOH) radical isomerization is an important low-temperature chain branching reaction within the mechanism of hydrocarbon oxidation. This isomerization may proceed via the migration of the α-hydrogen to the hydroperoxide group. In this work, a combination of high level composite methods-CBS-QB3, G3, and G4-is used to determine the high-pressure-limit rate parameters for the title reaction. Rate rules for H-migration reactions proceeding through 5-, 6-, 7-, and 8-membered ring transitions states are determined. Migrations from primary, secondary and tertiary carbon sites to the peroxy group are considered. Chirality is also investigated by considering two diastereomers for reactants and transition states with two chiral centers. This is important since chirality may influence the energy barrier of the reaction as well as the rotational energy barriers of hindered rotors in chemical species and transition states. The effect of chirality and hydrogen bonding interactions in the investigated energies and rate constants is studied. The results show that while the energy difference between two diastereomers ranges from 0.1-3.2 kcal/mol, chirality hardly affects the kinetics, except at low temperatures (atmospheric conditions) or when two chiral centers are present in the reactant. Regarding the effect of the H-migration ring size, it is found that in most cases, the 1,5 and 1,6 H-migration reactions have similar rates at low temperatures (below ∼830 K) since the 1,6 H-migration proceeds via a cyclohexane-like transition state similar to that of the 1,5 H-migration.

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n-Heptane cool flame chemistry: Unraveling intermediate species measured in a stirred reactor and motored engine

Abstract: S, et al. (2018) n-Heptane cool flame chemistry: Unraveling intermediate species measured in a stirred reactor and motored engine. Combustion and Flame 187: 199-216.

Cited by 67 publications

References 92 publications

Developing detailed chemical kinetic mechanisms for fuel combustion

Developing detailed chemical kinetic mechanisms for fuel combustion

Three-stage heat release in n-heptane auto-ignition

High-Pressure Limit Rate Rules for α-H Isomerization of Hydroperoxyalkylperoxy Radicals

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