Violation of collision limit in recently published reaction models

Chen, Dongping; Wang, Kun; Wang, Hai

doi:10.1016/j.combustflame.2017.08.005

Cited by 43 publications

(17 citation statements)

References 31 publications

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“…Although we performed high-level calculations for rate constants, directly using our results in a previously constructed combustion model will not necessarily lead to better agreement with experimental signals (such as final product distribution or ignition delay times), because of the uncertainty of the rate constants for other reactions that were previously added in the model, especially if the model contains some rate constants that were previously adjusted empirically to match the experimental data points. 94 Nevertheless, the process of gradually adding more reliable data to the models should in the long run produce more reliable models of combustion. In the atmosphere, the products of the reactions studied here are expected to further associate with O 2 , which may contribute to the formation of secondary organic aerosols (SOA) via the formation of low-volatility organic compounds.…”

Section: Mp-cvt/sct Rate Constant Path-averaged Generalized Transmismentioning

confidence: 99%

Degradation of Carbonyl Hydroperoxides in the Atmosphere and in Combustion

et al. 2017

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Oxygenates with carbonyl and hydroperoxy functional groups are important intermediates that are generated during the autoxidation of organic compounds in the atmosphere and during the autoignition of transport fuels. In the troposphere, the degradation of carbonyl hydroperoxides leads to low-vapor-pressure polyfunctional species that may precipitate in clouds and fog droplets or to the formation of secondary organic aerosols (SOAs). In combustion, the fate of carbonyl hydroperoxides is important for the performance of advanced combustion engines, especially for autoignition. A key fate of the carbonyl hydroperoxides is reaction with OH radicals, for which kinetics data are experimentally unavailable. Here, we study 4-hydroperoxy-2-pentanone (CHC(═O)CHCH(OOH)CH) as a model compound to clarify the kinetics of OH reactions with carbonyl hydroperoxides, in particular H atom abstraction and OH addition reactions. With a combination of electronic structure calculations, we determine previously missing thermochemical data, and with multipath variational transition state theory (MP-VTST), a multidimensional tunneling (MT) approximation, multiple-structure anharmonicity, and torsional potential anharmonicity, we obtained much more accurate rate constants than the ones that can computed by conventional single-structure harmonic transition state theory (TST) and than the empirically estimated rate constants that are currently used in atmospheric and combustion modeling. The roles of various factors in determining the rates are elucidated. The pressure-dependent rate constants for the addition reaction are computed using system-specific quantum RRK theory. The calculated temperature range is 298-2400 K, and the pressure range is 0.01-100 atm. The accurate thermodynamic and kinetics data determined in this work are indispensable in the global modeling of SOAs in atmospheric science and in the detailed understanding and prediction of ignition properties of hydrocarbons and alternative fuels.

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Section: Mp-cvt/sct Rate Constant Path-averaged Generalized Transmismentioning

confidence: 99%

Degradation of Carbonyl Hydroperoxides in the Atmosphere and in Combustion

et al. 2017

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“…Predictive kinetic models are often relatively large and may consist of thousands of interreacting chemical species . While handcrafting such models is error‐prone, automated model generation, as implemented in various forms (eg, EXGAS, Genesys, RMG), provides a systematic, reliable approach to this challenge.…”

Section: Introductionmentioning

confidence: 99%

Automated chemical resonance generation and structure filtration for kinetic modeling

Dana

Liu

Green

2019

Int J of Chemical Kinetics

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This work discusses efficient and automated methods for constructing a set of representative resonance structures for arbitrary chemical species, including radicals and biradicals, consisting of the elements H, C, O, N, and S. Determining the representative reactive structures of chemical species is crucial for identification of reactive sites and consequently applying the correct reaction templates to generate the set of important reactions during automated chemical kinetic model generation. We describe a fundamental set of resonance pathway types, accounting for simple resonating structures, as well as global approaches for polycyclic aromatic species. Automatically discovering potential localized structures along with filtration to identify the representative structures was shown to be robust and relatively fast. The algorithms discussed here were recently implemented in the Reaction Mechanism Generator (RMG) software. The final structures proposed by this method were found to be in reasonable agreement with quantum chemical computation results of localized structure contributions to the resonance hybrid.

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“…This barrierless reaction was included in the master equation by using an ILT of the collision-limited rate of the products. 33,39 The TS for aAdductFromRO2 is a concerted reaction with the SOMO perpendicular to the COO plane; the analogous reaction of other a-hydroxy peroxy radicals has been discussed previously. 20 The a-peroxy network also includes three intramolecular hydrogen abstraction reactions from the peroxy radical to form alkyl or alkoxy radicals.…”

Section: A-peroxy Networkmentioning

confidence: 93%