Chemical Kinetic Modeling Study of the Effects of Oxygenated Hydrocarbons on Soot Emissions from Diesel Engines

Westbrook, Charles K.; Pitz, William J.; Curran, Henry J.

doi:10.1021/jp056362g

Cited by 485 publications

(289 citation statements)

References 59 publications

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“…A chemical kinetic model for TPGME has been developed previously [1,11] to address its hightemperature chemistry and production of soot precursor species under conditions in diesel engines (high pressures 99 atm and low temperatures 767 K), and this model also took the surrogate approach, by only considering the isomer shown in Fig. 2.…”

Section: Figure 2: Isomer 3a Chosen To Represent Tpgme Mixture For Momentioning

confidence: 99%

“…2. Westbrook et al [11] presented comparisons of a range of oxygenated fuel additives (methanol, ethanol, dimethyl ether, dimethoxy methane, methyl butanoate, TPGME, dimethylcarbonate and DBM) and their effect on the formation of soot precursor species (ethylene, acetylene, propyne, etc.). It was found that the formation of these species was somewhat reliant on the percentage oxygen by weight in the overall fuel mixture (n-heptane + oxygenated additive in "air").…”

Section: Figure 2: Isomer 3a Chosen To Represent Tpgme Mixture For Momentioning

confidence: 99%

“…The C 1 -C 4 chemistry has been adopted from AramcoMech1.3 [15]. The high-temperature reactions of TPGME have also been updated from a previous TPGME mechanism [11]. For the initial fuel decomposition reactions, the rate constants for the four-centered molecular elimination reactions in TPGME were based on a similar reaction in methyl tert-butyl ether (MTBE).…”

Section: Reaction Rate Constantsmentioning

confidence: 99%

See 2 more Smart Citations

Experimental and kinetic modeling study of the shock tube ignition of a large oxygenated fuel: Tri-propylene glycol mono-methyl ether

Burke

Pitz

Curran

2015

Combustion and Flame

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Section: Figure 2: Isomer 3a Chosen To Represent Tpgme Mixture For Momentioning

confidence: 99%

Section: Figure 2: Isomer 3a Chosen To Represent Tpgme Mixture For Momentioning

confidence: 99%

Section: Reaction Rate Constantsmentioning

confidence: 99%

See 1 more Smart Citation

Experimental and kinetic modeling study of the shock tube ignition of a large oxygenated fuel: Tri-propylene glycol mono-methyl ether

Burke

Pitz

Curran

2015

Combustion and Flame

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“…The state of the art ethanol oxidation mechanism constructed by Marinov 21,22 predicts that a significant fraction of ethanol undergoes hydrogen atom abstraction from the methyl group (Reaction 7):…”

Section: Introductionmentioning

confidence: 99%

Computational Studies of Intramolecular Hydrogen Atom Transfers in the β-Hydroxyethylperoxy and β-Hydroxyethoxy Radicals

et al. 2007

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The -hydroxyethylperoxy (I) and -hydroxyethoxy (III) radicals are prototypes of species that can undergo hydrogen atom transfer across their intramolecular hydrogen bonds. These reactions may play an important role in both the atmosphere and in combustion systems. We have used density functional theory and composite electronic structure methods to predict the energetics of these reactions, RRKM/master equation simulations to model the kinetics of chemically activated I, and variational transition state theory (TST) to predict thermal rate constants for the 1,5-hydrogen shift in I (Reaction 1) and the 1,4-hydrogen shift in III (Reaction 2). Our multi-coefficient Gaussian-3 calculations predict that Reaction 1 has a barrier of 23.59 kcal/mol, and that Reaction 2 has a barrier of 22.71 kcal/mol. These predictions agree rather well with the MPW1K and BB1K density functional theory predictions but disagree with predictions based on B3LYP energies or geometries. Our RRKM/master equation simulations suggest that almost 50% of I undergoes a prompt hydrogen shift reaction at pressures up to 10 Torr, but the extent to which I is chemically activated is uncertain. For Reaction 1 at 298 K, the variational TST rate constant is ∼30% lower than the conventional TST result, and the microcanonical optimized multidimensional tunneling (µOMT) method predicts that tunneling accelerates the reaction by a factor of 3. TST calculations on Reaction 2 reveal no variational effect and a 298 K µOMT transmission coefficient of 10 5 . The Eckart method overestimates transmission coefficients for both reactions.

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“…The mechanism of Glaude et al indicates that most of the oxygen in the dimethyl carbonate goes into the direct production of CO 2 via dissociation of the methoxy carbonyl radical. Both Glaude 6 and Westbrook 21 remark that direct production of CO 2 in the combustion of oxygenated fuels is not an ideal utilization of oxygen because only one C atom per every two O atoms has been prevented from forming carbon-carbon bonds that characterize soot precursors.…”

Section: Introductionmentioning

confidence: 99%

Characterization of the Methoxy Carbonyl Radical Formed via Photolysis of Methyl Chloroformate at 193.3 nm

et al. 2007

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This study investigates two features of interest in recent work on the photolytic production of the methoxy carbonyl radical and its subsequent unimolecular dissociation channels. Earlier studies used methyl chloroformate as a photolytic precursor for the CH 3 OCO, methoxy carbonyl (or methoxy formyl) radical, which is an intermediate in many reactions that are relevant to combustion and atmospheric chemistry. That work evidenced two competing C-Cl bond fission channels, tentatively assigning them as producing groundand excited-state methoxy carbonyl radicals. In this study, we measure the photofragment angular distributions for each C-Cl bond fission channel and the spin-orbit state of the Cl atoms produced. The data shows bond fission leading to the production of ground-state methoxy carbonyl radicals with a high kinetic energy release and an angular distribution characterized by an anisotropy parameter, , of between 0.37 and 0.64. The bond fission that leads to the production of excited-state radicals, with a low kinetic energy release, has an angular distribution best described by a negative anisotropy parameter. The very different angular distributions suggest that two different excited states of methyl chloroformate lead to the formation of ground-and excited-state methoxy carbonyl products. Moreover, with these measurements we were able to refine the product branching fractions to 82% of the C-Cl bond fission resulting in ground-state radicals and 18% resulting in excitedstate radicals. The maximum kinetic energy release of 12 kcal/mol measured for the channel producing excitedstate radicals suggests that the adiabatic excitation energy of the radical is less than or equal to 55 kcal/mol, which is lower than the 67.8 kcal/mol calculated by UCCSD(T) methods in this study. The low-lying excited states of methylchloroformate are also considered here to understand the observed angular distributions. Finally, the mechanism for the unimolecular dissociation of the methoxy carbonyl radical to CH 3 + CO 2 , which can occur through a transition state with either cis or, with a much higher barrier, trans geometry, was investigated with natural bond orbital computations. The results suggest donation of electron density from the nonbonding C radical orbital to the σ* orbital of the breaking C-O bond accounts for the additional stability of the cis transition state.

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Chemical Kinetic Modeling Study of the Effects of Oxygenated Hydrocarbons on Soot Emissions from Diesel Engines

Cited by 485 publications

References 59 publications

Experimental and kinetic modeling study of the shock tube ignition of a large oxygenated fuel: Tri-propylene glycol mono-methyl ether

Experimental and kinetic modeling study of the shock tube ignition of a large oxygenated fuel: Tri-propylene glycol mono-methyl ether

Computational Studies of Intramolecular Hydrogen Atom Transfers in the β-Hydroxyethylperoxy and β-Hydroxyethoxy Radicals

Characterization of the Methoxy Carbonyl Radical Formed via Photolysis of Methyl Chloroformate at 193.3 nm

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