Premixed ignition behavior of alternative diesel fuel-relevant compounds in a motored engine experiment

Pitz

Westbrook

2008

Combustion and Flame

414

313

A detailed chemical kinetic mechanism has been developed and used to study the oxidation of methyl decanoate, a surrogate for biodiesel fuels. This model has been built by following the rules established by Curran et al. for the oxidation of n-heptane and it includes all the reactions known to be pertinent to both low and high temperatures.Computed results have been compared with methyl decanoate experiments in an engine and oxidation of rapeseed oil methyl esters in a jet stirred reactor. An important feature of this mechanism is its ability to reproduce the early formation of carbon dioxide that is unique to biofuels and due to the presence of the ester group in the reactant. The model also predicts ignition delay times and OH profiles very close to observed values in shock tube experiments fueled by n-decane. These model capabilities indicate that large nalkanes can be good surrogates for large methyl esters and biodiesel fuels to predict overall reactivity, but some kinetic details, including early CO 2 production from biodiesel fuels, can be predicted only by a detailed kinetic mechanism for a true methyl ester fuel.The present methyl decanoate mechanism provides a realistic kinetic tool for simulation of biodiesel fuels.3

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Detailed chemical kinetic oxidation mechanism for a biodiesel surrogate

Pitz

Westbrook

2008

Combustion and Flame

414

313

“…The oxidation of n-heptane was previously studied in engines [1][2][3][4][5] and in several types of laboratory reactors such as shock tubes [6][7][8][9][10][11], rapid compression machines [12,13], jetstirred reactors [14][15][16], flow reactors [17], and flames [18][19][20][21][22]. Most of these studies were carried out under conditions of high temperature oxidation (temperature typically above 800 K) and relatively little attention was paid to the low-temperature oxidation of n-heptane, especially regarding the characterization of oxygenated reaction products [12,13,[15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Experimental and modeling investigation of the low-temperature oxidation of n-heptane

Husson

Serinyel

et al. 2012

Combustion and Flame

174

240

The low-temperature oxidation of n-heptane, one of the reference species for the octane rating of gasoline, was investigated using a jet-stirred reactor and two methods of analysis: gas chromatography and synchrotron vacuum ultra-violet photo-ionization mass spectrometry (SVUV-PIMS) with direct sampling through a molecular jet. The second method allowed the identification of products, such as molecules with hydroperoxy functions, which are not stable enough to be detected using gas chromatography. Mole fractions of the reactants and reaction products were measured as a function of temperature (500-1100K), at a residence time of 2s, at a pressure of 800 torr (1.06 bar) and at stoichiometric conditions. The fuel was diluted in an inert gas (fuel inlet mole fraction of 0.005). Attention was paid to the formation of reaction products involved in the low temperature oxidation of n-heptane, such as olefins, cyclic ethers, aldehydes, ketones, species with two carbonyl groups (diones) and ketohydroperoxides. Diones and ketohydroperoxides are important intermediates in the low temperature oxidation of n-alkanes but their formation have rarely been reported. Significant amounts of organic acids (acetic and propanoic acids) were also observed at low temperature. The comparison of experimental data and profiles computed using an automatically generated detailed kinetic model is overall satisfactory. A route for the formation of acetic and propanoic acids was proposed. Quantum calculations were performed to refine the consumption routes of ketohydroperoxides towards diones.

“…These same methyl esters are found in biodiesel derived from other vegetable oils such as rapeseed oil, but the proportions differ. Methyl esters in particular methyl butanoate (n-C 3 H 7 C(=O)OCH 3 ) and methyl decanoate (n-C 9 H 19 C(=O)OCH 3 ) have been proposed as possible surrogates for biodiesel [1][2][3][4][5][6][7]. The present study is focused on combustion of methyl decanoate.…”

Section: Introductionmentioning

confidence: 99%

“…Previous studies of ignition and combustion of methyl decanoate have been focused on premixed systems [5][6][7]. The present study considers combustion of methyl decanoate in nonpremixed, aerodynamically strained flows.…”

Section: Introductionmentioning

confidence: 99%

Experimental and kinetic modeling study of extinction and ignition of methyl decanoate in laminar non-premixed flows

Seshadri

Proceedings of the Combustion Institute

et al. 2009

131

Methyl decanoate is a large methyl ester that can be used as a surrogate for biodiesel. In this experimental and computational study, the combustion of methyl decanoate is investigated in nonpremixed, nonuniform flows. Experiments are performed employing the counterflow configuration with a fuel stream made up of vaporized methyl decanoate and nitrogen, and an oxidizer stream of air. The mass fraction of fuel in the fuel stream is measured as a function of the strain rate at extinction, and critical conditions of ignition are measured in terms of the temperature of the oxidizer stream as a function of the strain rate. It is not possible to use a fully detailed mechanism for methyl decanoate to simulate the counterflow flames because the number of species and reactions is too large to employ with current flame codes and computer resources. Therefore a skeletal mechanism was deduced from a detailed mechanism of 8555 elementary reactions and 3036 species using ``directed relation graph'' method. This skeletal mechanism has only 713 elementary reactions and 125 species. Critical conditions of ignition were calculated using this skeletal mechanism and are found to agree well with experimental data. The predicted strain rate at extinction is found to be lower than the measurements. In general, the methyl decanoate mechanism provides a realistic kinetic tool for simulation of biodiesel fuels. Experimental and Kinetic Modeling Study of Extinction and Ignition of Methyl Decanoate in Laminar Nonpremixed Flows Experimental and Kinetic Modeling Study of Extinction and Ignition of Methyl Decanoate in Laminar Nonpremixed Flows AbstractMethyl decanoate is a large methyl ester that can be used as a surrogate for biodiesel. In this experimental and computational study, the combustion of methyl decanoate is investigated in nonpremixed, nonuniform flows. Experiments are performed employing the counterflow configuration with a fuel stream made up of vaporized methyl decanoate and nitrogen, and an oxidizer stream of air. The mass fraction of fuel in the fuel stream is measured as a function of the strain rate at extinction, and critical conditions of ignition are measured in terms of the temperature of the oxidizer stream as a function of the strain rate. It is not possible to use a fully detailed mechanism for methyl decanoate to simulate the counterflow flames because the number of species and reactions is too large to employ with current flame codes and computer resources. Therefore a skeletal mechanism was deduced from a detailed mechanism of 8555 elementary reactions and 3036 species using "directed relation graph" method. This skeletal mechanism has only 713 elementary reactions and 125 species. Critical conditions of ignition were calculated using this skeletal mechanism and are found to agree well with experimental data. The predicted strain rate at extinction is found to be lower than the measurements. In general, the methyl decanoate mechanism provides a realistic kinetic tool for simulation of biodiesel fuels.