Auto-ignition and chemical kinetic mechanisms of HCCI combustion

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

doi:10.1533/9781845693541.5.433

Cited by 18 publications

(11 citation statements)

References 29 publications

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“…Dimethyl ether, CH 3 OCH 3 (DME), is a possible diesel fuel additive/surrogate; it has a high cetane number (>55) and gives lower CO and particulate emissions, but its effects on NOx emissions can be variable. − Usefully, from an economic point of view, it can be produced relatively cheaply from hydrocarbon feedstocks including biomass. , A number of kinetic models for DME combustion have been developed. − With the development of HCCI (homogeneous charge compression ignition) engines, there is increased interest in low temperature combustion as this chemistry controls the combustion process . The initial propagation reaction in low temperature combustion and the first step in atmospheric oxidation is the reaction with OH, forming the methylmethoxy radical, CH 3 OCH 2 OH + CH 3 OCH 3 → normalH 2 normalO + CH 3 OCH 2 Reaction 1 is followed, in both combustion and atmospheric chemistry, by addition of O 2 .…”

Section: Introductionmentioning

confidence: 99%

“…7−10 With the development of HCCI (homogeneous charge compression ignition) engines, there is increased interest in low temperature combustion 11 as this chemistry controls the combustion process. 12 The initial propagation reaction in low temperature combustion and the first step in atmospheric oxidation is the reaction with OH, forming the methylmethoxy radical, CH 3 (R1)…”

Section: ■ Introductionmentioning

confidence: 99%

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Experimental and Theoretical Study of the Kinetics and Mechanism of the Reaction of OH Radicals with Dimethyl Ether

et al. 2013

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The reaction of OH with dimethyl ether (CH3OCH3) has been studied from 195 to 850 K using laser flash photolysis coupled to laser induced fluorescence detection of OH radicals. The rate coefficient from this work can be parametrized by the modified Arrhenius expression k = (1.23 ± 0.46) × 10(-12) (T/298)(2.05±0.23) exp((257 ± 107)/T) cm(3) molecule(-1) s(-1). Including other recent literature data (923-1423 K) gives a modified Arrhenius expression of k1 = (1.54 ± 0.48) × 10(-12) (T/298 K)(1.89±0.16) exp((184 ± 112)/T) cm(3) molecule(-1) s(-1) over the range 195-1423 K. Various isotopomeric combinations of the reaction have also been investigated with deuteration of dimethyl ether leading to a normal isotope effect. Deuteration of the hydroxyl group leads to a small inverse isotope effect. To gain insight into the reaction mechanisms and to support the experimental work, theoretical studies have also been undertaken calculating the energies and structures of the transition states and complexes using high level ab initio methods. The calculations also identify pre- and post-reaction complexes. The calculations show that the pre-reaction complex has a binding energy of ~22 kJ mol(-1). Stabilization into the complex could influence the kinetics of the reaction, especially at low temperatures (<300 K), but there is no direct evidence of this occurring under the experimental conditions of this study. The experimental data have been modeled using the recently developed MESMER (master equation solver for multi energy well reactions) code; the calculated rate coefficients lie within 16% of the experimental values over the temperature range 200-1400 K with a model based on a single transition state. This model also qualitatively reproduces the observed isotope effects, agreeing closely above ~600 K but overestimating them at low temperatures. The low temperature differences may derive from an inadequate treatment of tunnelling and/or from an enhanced role of an outer transition state leading to the pre-reaction complex.

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Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Experimental and Theoretical Study of the Kinetics and Mechanism of the Reaction of OH Radicals with Dimethyl Ether

et al. 2013

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“…Alkylperoxy radicals play a key role in the oxidation of fuels at cool-flame temperatures and the competition between their isomerization to hydroperoxyalkyl radicals or dissociation is central to an understanding of combustion in novel internal combustion engines under active development …”

Section: Introductionmentioning

confidence: 99%

Enthalpies of Formation and Bond Dissociation Energies of Lower Alkyl Hydroperoxides and Related Hydroperoxy and Alkoxy Radicals

et al. 2008

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The enthalpies of formation and bond dissociation energies, D (ROO-H)and D(R-OOH) of alkyl hydroperoxides, ROOH, alkyl peroxy, RO, and alkoxide radicals, RȮ , have been computed at CBS-QB3 and APNO levels of theory via isodesmic and atomization procedures for R ) methyl, ethyl, n-propyl and isopropyl and n-butyl, tert-butyl, isobutyl and sec-butyl. We show that D(ROO-H) ≈ 357, D(RO-OH) ≈ 190 and D(RO-Ȯ ) ≈ 263 kJ mol -1 for all R, whereas both D(R-Ȯ O) and D(R-OOH)strengthen with increasing methyl substitution at the R-carbon but remain constant with increasing carbon chain length. We recommend a new set of group additivity contributions for the estimation of enthalpies of formation and bond energies.

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“…The hydrocarbon oxidation is divided into three temperature regimes: low-temperature regime, intermediate-temperature and hightemperature regime [28]. The low-temperature regime defined as low temperature heat release (LTHR) typically occurs at temperatures from 600 to 800 K [29]. The intermediate-temperature regime is characterized by both the negative temperature coefficient (NTC) zone and the intermediate temperature heat release (ITHR).…”

Section: Heat Release Analysismentioning

confidence: 99%

Characterization of Low Temperature Reactions in the Standard Cooperative Fuel Research (CFR) Engine

Waqas¹,

Hoth

Kolodziej

et al. 2019

SAE Int. J. Engines

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Up to date many proposals for the fuel rating in the Spark Ignition (SI) engine have been suggested and there is still no consensus on this and the industry is still using RON and MON tests to rate the fuels and there is a need to come up with new fuel rating system. The knocking tendency of the fuel in SI engines is primarily governed by the end-gas auto-ignition. Another combustion mode, Homogeneous Charge Compression Ignition (HCCI) is also driven by auto-ignition of the complete charge inside the cylinder. Fundamentally, the combustion process in both combustion modes is driven by auto-ignition and HCCI combustion mode can be used to understand the knocking behavior in SI engines. The lean combustion environment in HCCI mode provides a good platform to replicate the operating conditions of modern SI engines which are operating at boosted pressures and low intake temperatures and understanding of the fuel knocking behavior under such conditions is vital for achieving high efficient engines.Therefore in this study, HCCI combustion will be used in the standard CFR engine to understand the auto-ignition behavior of the fuels for SI engines. For this purpose, three fuel blends were selected which had the research octane number equal to 90. The standard CFR engine was operated with varying intake pressures and temperatures under HCCI combustion mode. The Lund-Chevron HCCI fuel number was used to rate the fuels and this was compared with RON and MON of the blends. It was found that HCCI combustion could be used to rate the fuels with the standard CFR engine with minor modifications to accommodate the boosted conditions without affecting the geometry and the flow inside the CFR engine. Low temperature reactions were observed and were correlated with the Lund-Chevron HCCI fuel numbers.

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Auto-ignition and chemical kinetic mechanisms of HCCI combustion

Cited by 18 publications

References 29 publications

Experimental and Theoretical Study of the Kinetics and Mechanism of the Reaction of OH Radicals with Dimethyl Ether

Experimental and Theoretical Study of the Kinetics and Mechanism of the Reaction of OH Radicals with Dimethyl Ether

Enthalpies of Formation and Bond Dissociation Energies of Lower Alkyl Hydroperoxides and Related Hydroperoxy and Alkoxy Radicals

Characterization of Low Temperature Reactions in the Standard Cooperative Fuel Research (CFR) Engine

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