Pyrolysis and oxidation of decalin at elevated pressures: A shock-tube study

Ignition delay times and ethylene concentration time-histories were measured behind reflected shock waves during decalin oxidation and pyrolysis. Ignition delay measurements were conducted for gas-phase decalin/air mixtures over temperatures of 769–1202 K, pressures of 11.7–51.2 atm, and equivalence ratios of 0.5, 1.0, and 2.0. Negative-temperature-coefficient (NTC) behavior of decalin autoignition was observed, for the first time, at temperatures below 920 K. Current ignition delay data are in good agreement with past shock tube data in terms of pressure dependence but not equivalence ratio dependence. Ethylene mole fraction and fuel absorbance time-histories were acquired using laser absorption at 10.6 and 3.39 μm during decalin pyrolysis for mixtures of 2200–3586 ppm decalin/argon at pressures of 18.2–20.2 atm and temperatures of 1197–1511 K. Detailed comparisons of these ignition delay and species time-history data with predictions based on currently available decalin reaction mechanisms are presented, and preliminary suggestions for the adjustment of some key rate parameters are made.     

Ignition properties of n-butane and iso-butane in a rapid compression machine

Autoignition delay times of n-butane and iso-butane have been measured in a Rapid Compression Machine in the temperature range 660–1010 K, at pressures varying from 14 to 36 bar and at equivalence ratios φ = 1.0 and φ = 0.5. Both butane isomers exhibit a negative-temperature-coefficient (NTC) region and, at low temperatures, two-stage ignition. At temperatures below ～900 K, the delay times for iso-butane are longer than those for the normal isomer, while above this temperature both butanes give essentially the same results. At temperatures above ～720 K the delay times of the lean mixtures are twice those for stoichiometric compositions; at T < 720 K, the equivalence ratio is seen to have little influence on the ignition behavior. Increasing the pressure from 15 bar to 30 bar decreases the amplitude of the NTC region, and reduces the ignition delay time for both isomers by roughly a factor of 3. In the region in which two-stage ignition is observed, 680–825 K, the duration of the first ignition stage decreases sharply in the range 680–770 K, but is essentially flat above 770 K. Good quantitative agreement is found between the measurements and calculations for n-butane using a comprehensive model for butane ignition, including both delay times in the two-stage region, with substantial differences being observed for iso-butane, particularly in the NTC region.     

A comprehensive experimental and modeling study of iso-pentanol combustion

Biofuels are considered as potentially attractive alternative fuels that can reduce greenhouse gas and pollutant emissions. iso-Pentanol is one of several next-generation biofuels that can be used as an alternative fuel in combustion engines. In the present study, new experimental data for iso-pentanol in shock tube, rapid compression machine, jet stirred reactor, and counterflow diffusion flame are presented. Shock tube ignition delay times were measured for iso-pentanol/air mixtures at three equivalence ratios, temperatures ranging from 819 to 1252 K, and at nominal pressures near 40 and 60 bar. Jet stirred reactor experiments are reported at 5 atm and five equivalence ratios. Rapid compression machine ignition delay data was obtained near 40 bar, for three equivalence ratios, and temperatures below 800 K. Laminar flame speed data and non-premixed extinction strain rates were obtained using the counterflow configuration. A detailed chemical kinetic model for iso-pentanol oxidation was developed including high- and low-temperature chemistry for a better understanding of the combustion characteristics of higher alcohols. First, bond dissociation energies were calculated using ab initio methods, and the proposed rate constants were based on a previously presented model for butanol isomers and n-pentanol. The model was validated against new and existing experimental data at pressures of 1–60 atm, temperatures of 650–1500 K, equivalence ratios of 0.25–4.0, and covering both premixed and non-premixed environments. The method of direct relation graph (DRG) with expert knowledge (DRGX) was employed to eliminate unimportant species and reactions in the detailed mechanism, and the resulting skeletal mechanism was used to predict non-premixed flames. In addition, reaction path and temperature A-factor sensitivity analyses were conducted for identifying key reactions at various combustion conditions.     

Bio-butanol: Combustion properties and detailed chemical kinetic model

Autoignition delay time measurements were performed at equivalence ratios of 0.5, 1 and 2 for butan-1-ol at reflected shock pressures of 1, 2.6 and 8 atm at temperatures from 1100 to 1800 K. High-level ab initio calculations were used to determine enthalpies of formation and consequently bond dissociation energies for each bond in the alcohol. A detailed chemical kinetic model consisting of 1399 reactions involving 234 species was constructed and tested against the delay times and also against recent jet-stirred reactor speciation data with encouraging results. The importance of enol chemistry is highlighted.     

An experimental and kinetic modelling study of n-butyl formate combustion

The oxidation of n-butyl formate, a potential biofuel candidate, is studied using three different experimental approaches. Ignition delay times have been measured for stoichiometric mixtures of fuel and air for pressures of about 20 and 90 bar at temperatures from 846 up to 1205 K in a high-pressure shock tube. A rapid compression machine has been used to determine the low-temperature ignition delay times for stoichiometric mixtures at pressures close to 20 bar over the temperature range from 646 K up to 861 K. Laminar burning velocities have been determined for stoichiometric ratios ranging from 0.8 to 1.2 using the high-pressure chamber method combined with an optical Schlieren cinematography setup in order to acquire experimental data at elevated pressures of about 10 bar and a temperature of 373 K. A detailed kinetic model has been constructed including high-temperature and low-temperature reaction pathways. The enthalpies of formation, entropies, and specific heats at constant pressure for the fuel, its primary radicals, and several combustion intermediates have been computed with the CBS-QB3 methods and included in the mechanism. This model was validated successfully against the presented data and used to elucidate the combustion of this interesting ester. The importance of accurate inclusion of the low-temperature peroxy chemistry has been highlighted through sensitivity and reaction path analysis. This study presents the first combustion study of n-butyl formate and leads to an improved understanding of the chemical kinetics of alkyl ester oxidation.     

An experimental and modeling study of the low- and high-temperature oxidation of cyclohexane

The experimental study of the oxidation of cyclohexane has been performed in a jet-stirred reactor at temperatures ranging from 500 to 1100 K (low- and intermediate temperature zones including the negative temperature-coefficient area), at a residence time of 2 s and for dilute mixtures with equivalence ratios of 0.5, 1, and 2. Experiments were carried out at quasi-atmospheric pressure (1.07 bar). The fuel and reaction product mole fractions were measured using online gas chromatography. A total of 34 reaction products have been detected and quantified in this study. Typical reaction products formed in the low-temperature oxidation of cyclohexane include cyclic ethers (1,2-epoxycyclohexane and 1,4-epoxycyclohexane), 5-hexenal (formed from the rapid decomposition of 1,3-epoxycyclohexane), cyclohexanone, and cyclohexene, as well as benzene and phenol. Cyclohexane displays high low-temperature reactivity with well-marked negative temperature-coefficient (NTC) behavior at equivalence ratios 0.5 and 1. The fuel-rich system (? = 2) is much less reactive in the same region and exhibits no NTC. To the best of our knowledge, this is the first jet-stirred reactor study to report NTC in cyclohexane oxidation. Laminar burning velocities were also measured by the heated burner method at initial gas temperatures of 298, 358, and 398 K and at 1 atm. The laminar burning velocity values peak at ? = 1.1 and are measured as 40 and 63.1 cm/s for T_i = 298 and 398 K, respectively. An updated detailed chemical kinetic model including low-temperature pathways was used to simulate the present (jet-stirred reactor and laminar burning velocity) and literature experimental (laminar burning velocity, rapid compression machine, and shock tube ignition delay times) data. Reasonable agreement is observed with most of the products observed in our reactor, as well as the literature experimental data considered in this paper.     

A detailed experimental and kinetic modeling study of n-decane oxidation at elevated pressures

The oxidation of n-decane/oxygen/nitrogen is studied at stoichiometric conditions of 1000 ppm fuel in the Princeton variable pressure flow reactor at temperatures of 520–830 K and pressures of 8 and 12.5 atm. The overall oxidative reactivity of n-decane is observed in detail to show low temperature, negative temperature coefficient (NTC) and hot ignition regimes. Detailed temporal speciation studies are performed at reactor initial temperatures of 533 K and 740 K at 12.5 atm pressure and 830 K at 8 atm pressure. Significant amounts of large olefins are produced at 830 K, at conditions of transition from NTC to hot ignition behavior. The predictions using available chemical kinetic models for n-decane oxidation are compared against each other and the experiments. Only the kinetic models of Westbrook et al., Ranzi et al., and Biet et al. capture the NTC behavior exhibited by n-decane. However, each of these models yields varying disparities in the mechanistic predictions of major intermediate species, including ethylene and formaldehyde. Analyses of the Westbrook et al. model are compared with the new data. The predicted double-peaked species yield of ethylene, a behavior not found for the other models or in the experimental observations results from deficiencies in the C₂ chemistry. Mechanistic validation information about fuel oxidation chemistry is also provided by the measurement of various larger carbon number alkene isomers at 830 K and 8 atm. The modeling analysis suggests that in addition to n-alkyl beta-scission chemistry, alkyl peroxy radical chemistry contributes significantly to the formation of these alkenes. Specific reaction pathways and rate constants which affect the computation of these observations are discussed.     

Autoignition of surrogate biodiesel fuel (B30) at high pressures: Experimental and modeling kinetic study

Ignition delay times of surrogate biodiesel fuels were measured in a high-pressure shock tube over a wide range of experimental conditions (pressures of 20 and 40 bar, equivalence ratios in the range 0.5–1.5, and temperatures ranging from 700 to 1200 K). A detailed chemical kinetic mechanism developed for the oxidation of a biodiesel fuel and a B30 biodiesel surrogate (49% n-decane, 21% 1-methylnaphthalene, and 30% methyloctanoate in mol%) was used to simulate the present experiments. Cross reactions between radicals from the three fuel components and reactions of methylnaphthalene oxidation recently proposed in the literature were introduced into the model in order to improve ignition delay time predictions at low temperatures. The new scheme (7865 reversible reactions and 1975 species) yields improved model predictions of concentration profiles measured earlier in a jet-stirred reactor, and also represents fairly well the present experimental data over the entire range of conditions of this study. Sensitivity analyses and reaction path analyses were used to rationalize the results.     

A high pressure shock tube study of n-propylbenzene oxidation and its comparison with n-butylbenzene

Ignition delay times have been measured for mixtures of n-propylbenzene in air (≈21% O₂, ≈79% N₂) at equivalence ratios of 0.29, 0.48, 0.96 and 1.92 and at reflected shock pressures of 1, 10 and 30 atm in a heated high-pressure shock tube over a wide temperature range (1000–1600 K). The effects of reflected shock pressure and of equivalence ratio on ignition delay time were determined and common trends highlighted. Simulations were carried out using the n-propylbenzene sub-mechanism contained in an n-butylbenzene reaction mechanism available in the literature. This kinetic model was improved by including pressure dependent reactions which were not in place previously and the addition of the NUI Galway C₀–C₄ sub-mechanism. These simulations showed very good agreement with the experimental data. Additionally a comparison is made with experimental data previously obtained and published for n-butylbenzene over the same range of conditions and common trends are highlighted.     

Ignition delay times of low-vapor-pressure fuels measured using an aerosol shock tube

Gas-phase ignition delay times were measured behind reflected shock waves for a wide variety of low-vapor-pressure fuels. These gas-phase measurements, without the added convolution with evaporation times, were made possible by using an aerosol shock tube. The fuels studied include three large normal alkanes, n-decane, n-dodecane and n-hexadecane; one large methyl ester, methyl decanoate; and several diesel fuels, DF-2, with a range of cetane indices from 42 to 55. The reflected shock conditions of the experiments covered temperatures from 838 to 1381 K, pressures from 1.71 to 8.63 atm, oxygen concentrations from 1 to 21%, and equivalence ratios from 0.1 to 2. Ignition delay times were measured using sidewall pressure, IR laser absorption by fuel at 3.39 μm, and CH^* and OH^* emission. Measurements are compared to previous studies using heated shock tubes and current models. Model simulations show similar trends to the current measurement except in the case of n-dodecane/21% O₂/argon experiments. At higher temperatures, e.g. 1250 K, the measured ignition delay times for these mixtures are significantly longer in lean mixtures than in rich mixtures; current models predict the opposite trend. As well, the current measurements show significantly shorter ignition delay times for rich mixtures than the model predictions.     

Effects of high pressure,high temperature and dilution on laminar burning velocities and Markstein lengths of iso-octane/air mixtures

Spherically expanding flames are employed to measure flame velocities, from which are derived the corresponding laminar burning velocities at zero stretch rate. Iso-octane/air mixtures at initial temperatures between 323 and 473 K, and pressures between 1 and 10 bar, are studied over an extensive range of equivalence ratios, using a high-speed shadowgraph system. Effects of dilution are investigated with nitrogen and for several dilution percentages (from 5 to 25 vol% N₂). Over 270 experimental values have been obtained, providing an exhaustive data base for iso-octane/air combustion. Experimental results are in excellent agreement with recently published experimental data. An explicit correlation giving the laminar burning velocity from the initial pressure, the initial temperature, the dilution rate, and the equivalence ratio is finally proposed. Computed results using the two kinetic schemes and the Cantera code are compared to the present measurements. It is found that the mechanisms yield substantially higher values of laminar flame velocities than the present experimental results. Effects of oxygen enrichment are also investigated. A linear trend relating the percentage of oxygen in air and the unstretched laminar burning velocity is observed. Effects of high pressure, high temperature, and high dilution rate on Markstein lengths are also studied. As already done for the laminar burning velocity, an empirical correlation is proposed to describe the Markstein length for burned gases as a function of initial temperature and pressure, for equivalence ratios between 0.9 and 1.1, which has never been done before in the literature.     

Short chemical-kinetic mechanisms for low-temperature ignition of propane and ethane

The low-temperature (500–1000 K) ignition of propane–air and ethane–air mixtures is studied in this work. An original detailed mechanism of 235 elementary reactions among 40 species, which models the ignition time of these fuels under a wide range of conditions for initial temperatures above about 1000 K, the so-called San Diego Mech, is revised and augmented to produce the two-stage ignition and negative-temperature-coefficient (NTC) behavior seen experimentally for these fuels below 1000 K. By using available kinetic data and introducing applicable steady-state approximations, it is shown that adding only four more reactions for each fuel to the original chemical mechanism succeeds in modeling the low-temperature regime. The predictions of this mechanism are compared with two types of experimental measurements, namely those from rapid-compression machines and those from static-reactor vessels, where NTC behavior and two-stage ignition are observed. The numerical results for the ignition delay exhibit reasonably good agreement with the experimental data from the rapid-compression machine, both qualitatively and quantitatively, as do the predictions for the static reactor, when radical loss by surface reactions is taken into account in an approximate manner. These results thus extend the range of applicability of the mechanism to lower temperatures that are of interest in various applications, such as HCCI engines.     

Soot formation characteristics and PAH formation process in a micro flow reactor with a controlled temperature profile

A micro flow reactor with a controlled temperature profile was examined with regard to its capabilities to investigate soot formation characteristics of rich methane/air mixtures and the formation process of polycyclic aromatic hydrocarbons (PAHs) of rich acetylene/air mixtures. In the experiment for a methane/air mixture, four kinds of flame and soot responses to equivalence ratio (1.5–4.5) and inlet mean flow velocity (5–40 cm/s) were observed: soot formation without a flame; a flame with soot formation; a flame without soot formation; and neither a flame nor soot formation. Soot formation was observed at high equivalence ratio and low flow velocity. Sooting limits depending on equivalence ratio and flow velocity (residence time) were successfully identified by the present micro flow reactor. To investigate the PAH formation process, the micro flow reactor was employed for a rich acetylene/air mixture at equivalence ratios of 4, 5 and 6 at an inlet mean flow velocity of 2 cm/s and gas sampling experiments were conducted at temperatures from 600 to 1000 K. Temperature dependence of mole fractions of benzene, styrene, naphthalene, phenanthrene, indene, acenaphthylene and biphenyl was successfully obtained and larger PAHs such as pyrene and coronene were not observed in this study. One-dimensional computation with the ABF 2.99 mechanism predicted a benzene mole fraction three times higher than the experimental result. The modification of the ABF 2.99 mechanism using recent benzene reactions greatly improved the prediction of the benzene mole fraction. The rate of production analysis was carried out and PAH formation in the micro flow reactor was investigated in detail.     

Experimental and surrogate modeling study of gasoline ignition in a rapid compression machine

The use of gasoline in Homogeneous Charge Compression Ignition engines has propelled the need to better understand compression ignition processes for gasoline under engine-like conditions. In order to quantify low-temperature heat release and to provide fundamental validation data for chemical kinetic models, it is imperative to study autoignition phenomena under well-controlled conditions. However, there is a significant lack of autoignition delay data in the low temperature regime. Recognizing the need for kinetic information at high pressures and low-to-intermediate temperatures, this work aims to fill this void by conducting an experimental study of gasoline autoignition in a Rapid Compression Machine (RCM) to characterize the ignition response of gasoline + air mixtures over a wide range of compression temperatures at compression pressures of 20 and 40 bar with equivalence ratios ranging from 0.3 to 1.0. Results from the RCM experiments are also simulated using a four-component gasoline surrogate model which includes n-heptane, iso-octane, toluene, and 2-pentene. For the conditions investigated, good agreement between the experiments and the four-component surrogate model, in terms of first-stage and total ignition delay times as well as the comparison of measured and simulated pressure traces, is demonstrated. Kinetic analysis is further conducted to understand the role of the different hydrocarbon classes present in gasoline in controlling autoignition.     

A computational study and correlation of premixed isooctane air laminar reaction fronts diluted with EGR

The current work investigates the propagation of premixed laminar reaction fronts for mixtures of isooctane–air and recirculated combustion products (or EGR) under high pressure and temperature conditions. The work uses a transient one-dimensional flame simulation with a skeletal 215 species chemical kinetic mechanism to generate laminar burning velocity and front thickness predictions. The simulation was exercised over fuel–air equivalence ratios, unburned gas temperatures, pressures and EGR levels ranging from 0.1 to 1.0, 400 to 1000 K, 1 to 250 bar, and 0% to 60% (by mass) respectively, a range extending beyond that of previous researchers. Steady reaction fronts with burning velocities in excess of 5 cm/s could not be established under all of these conditions, especially when burned gas temperatures were below 1450 K and/or when characteristic reaction front propagation times were on the order of the unburned gas ignition delay. For a given pressure, T_u and T_b, the burning velocity of an EGR dilute mixture was found to be lower than that of an air dilute mixture, with the decrease in burning velocity attributed primarily to the reduced oxygen concentration’s effect on chemistry. Steady premixed laminar burning velocities were correlated using a modified two-equation form based on the asymptotic structure of a laminar flame, which produced an average error of 3.4% between the simulated and correlated laminar burning velocities, with a standard deviation of 4.3%, while additional correlations were constructed for reaction front thickness and adiabatic flame temperature. Correlations are presented based on a non-product equivalence ratio φ and a fraction of stoichiometric combustion products X_SCP. Conversion factors are provided to facilitate application to modern direct injection internal combustion engines with inherent charge stratification where the local global Φ is different from the global Φ of the residual gas.     

Negative pressure dependence of mass burning rates of H2/CO/O2/diluent flames at low flame temperatures

Experimental measurements of burning rates, analysis of the key reactions and kinetic pathways, and modeling studies were performed for H₂/CO/O₂/diluent flames spanning a wide range of conditions: equivalence ratios from 0.85 to 2.5, flame temperatures from 1500 to 1800 K, pressures from 1 to 25 atm, CO fuel fractions from 0 to 0.9, and dilution concentrations of He up to 0.8, Ar up to 0.6, and CO₂ up to 0.4. The experimental data show negative pressure dependence of burning rate at high pressure, low flame temperature conditions for all equivalence ratios and CO fractions as high as 0.5. Dilution with CO₂ was observed to strengthen the pressure and temperature dependence compared to Ar-diluted flames of the same flame temperature. Simulations were performed to extend the experimentally studied conditions to conditions typical of gas turbine combustion in Integrated Gasification Combined Cycle processes, including preheated mixtures and other diluents such as N₂ and H₂O.Substantial differences are observed between literature model predictions and the experimental data as well as among model predictions themselves – up to a factor of three at high pressures. The present findings suggest the need for several rate constant modifications of reactions in the current hydrogen models and raise questions about the sufficiency of the set of hydrogen reactions in most recent hydrogen models to predict high pressure flame conditions relevant to controlling NO_x emissions in gas turbine combustion. For example, the reaction O + OH + M = HO₂ + M is not included in most hydrogen models but is demonstrated here to significantly impact predictions of lean high pressure flames using rates within its uncertainty limits. Further studies are required to reduce uncertainties in third body collision efficiencies for and fall-off behavior of H + O₂(+M) = HO₂(+M) in both pure and mixed bath gases, in rate constants for HO₂ reactions with other radical species at higher temperatures, and in rate constants for reactions such as O + OH + M that become important under the present conditions in order to properly characterize the kinetics and predict global behavior of high-pressure H₂ or H₂/CO flames.     

Measurements of the auto-ignition of n-heptane/toluene mixtures using a rapid compression machine

Ignition delay times of undiluted stoichiometric n-heptane/toluene mixtures have been measured in a rapid compression machine (RCM) for pure n-heptane and for an increasing concentration of toluene by liquid volume (25–100%) in the mixture, mainly at two different molar densities (150 and 180 mol/m³). Initial pressures and temperatures were varied respectively in the 0226–0298 bar range and in the 299–352 K range, in order to allow compressed pressures and temperatures respectively in the 7.95–10.38 bar range and in the 710–814 K range.No ignition was observed for pure toluene due most probably to the variation of the final temperature and pressure in the combustion chamber during the very long ignition times of pure toluene at the experimental conditions considered in this work. The ignition delay variation at fixed temperature and the relative variation of the two-stage ignition times are reported. It is shown how the mixture behavior seems to be governed by the n-heptane chemistry for low toluene amount, while an increase of toluene concentration causes longer ignition delay times.Numerical modeling of the experiments with a recent Lawrence Livermore chemical mechanism for surrogate fuels shows that the results agree fairly well in the case of low and mid proportion of toluene by liquid volume. The single-zone model has allowed to extend the temperature range of investigation, showing that the low temperature range is the most influenced by the presence of toluene.     

Effect of injection pressure on performance,emission and combustion characteristics of high linolenic linseed oil methyl ester in a DI diesel engine

Due to the increasing demand for fossil fuels and environmental threat, a number of renewable sources of energy have been studied worldwide. In the present investigation a high linolenic linseed oil methyl ester has been investigated in a constant speed, DI diesel engine with varied fuel injection pressures (200, 220 and 240 bar). The main objective of this study is to investigate the effect of injection pressures on performance, emissions and combustion characteristics of the engine. The test results show that the optimum fuel injection pressure is 240 bar with linseed methyl ester. At this optimized pressure the thermal efficiency is similar to diesel and a reduction in carbon monoxide, unburned hydrocarbon and smoke emissions with an increase in the oxides of nitrogen was noticed compared to diesel. The combustion analysis shows that, the ignition delay is lower at higher injection pressures compared to diesel and the peak pressure is also higher at full load. The combustion duration was almost same at all the injection pressures. It is concluded that linseed methyl ester at 240 bar injection pressure is more efficient than 200 and 220 bar, except for nitrogen oxides emission.     

A shock tube study of methyl decanoate autoignition at elevated pressures

A shock tube study of the autoignition of methyl decanoate, a candidate surrogate for biodiesel fuels containing large methyl esters, has been carried out. Ignition delay times were measured in reflected-shock-heated gases by monitoring electronically-excited OH chemiluminescence and pressure. Methyl decanoate/air mixtures were studied at equivalence ratios of 0.5, 1.0, and 1.5, at temperatures from 653 to 1336 K, and for pressures around 15–16 atm. The experimental results illustrate negative-temperature-coefficient behavior characteristic of alkanes, with ignition delay times very similar at high temperatures and somewhat longer at low temperatures than those for n-decane. Experimental results are compared to the kinetic modeling predictions of Herbinet et al. [Combust. Flame 154 (2008) 507–528] with remarkable agreement. Both reaction flux analysis and the comparison of experimental methyl decanoate and n-decane ignition delay times illustrate the importance of the long alkyl chain in controlling methyl decanoate overall reactivity and the subtle role the methyl ester group has on inhibiting low-temperature reactivity.     

High pressure study of 1,3,5-trimethylbenzene oxidation

The high pressure and high temperature kinetics of the 1,3,5-trimethylbenzene oxidation were investigated in the High Pressure Single Pulse Shock Tube at University of Illinois at Chicago. Experiments were performed at nominal reflected shock pressures of 20 and 50 atm, for three different equivalence ratios (Ф = 0.51, 0.95 and 1.86) and for a temperature range of 1017–1645 K. A variety of stable species ranging from aliphatic hydrocarbons to single ring and polycyclic aromatic hydrocarbons were sampled from the shock tube and analyzed using standard gas chromatographic techniques.A detailed chemical kinetic model was developed to simulate the fuel and oxygen decay and the stable intermediate species profiles as obtained from the high pressure oxidation experiments. The model shows satisfactory predictions for the formation and consumption of most of the major intermediates.