Detailed Chemical Kinetic Reaction Mechanism Research Articles

Oxidation study of small hydrocarbons at elevated pressure. Part I: Neat 1,3-butadiene

To study the formation pathways of aromatic compounds in the oxidation process of soot precursors under different equivalent ratios (φ), two parts of work were carried out. The present work was the part I: the oxidation of 1,3-butadiene (1,3-C4H6) was studied in a jet-stirred reactor at high-pressure (12 atm) within a temperature range covering 575–1075 K, at fuel equivalence ratios (φ) of 0.5 and 3.0. Part II focused on the study of oxidation of a two-compound mixture of acetylene and 1,3-butadiene. Mole fraction profiles of 20 species obtained by GC/MS analysis were identified and quantified. The measured species profiles serve as a data base for the further development of a detailed chemical kinetic reaction mechanism AramcoMech 3.0 generated by Zhou et al. previously for describing the ignition delay time and laminar flame speed of 1,3-butadien. The resulting reaction mechanism comprising 625 species and 3188 reactions was found to be able to describe credibly the experimental species profiles. Rate-of-production (ROP) analysis reveals that addition reactions of H and OH radicals to 1,3-C4H6 are the major channels governing 1,3-C4H6 consumption under both fuel-lean and fuel-rich conditions. Acetylene (C2H2), vinyl acetylene (C4H4), and propargyl radicals (C3H3) are playing important roles within the formation of mono-aromatics. Here, benzene is mainly formed via the C2 + C4 pathways instead of the C1 + C5 routes. Furthermore, C3H3 radicals were found to play a key role within C6H5CH3 formation. Naphthalene are formed by the reactions of C6H6 and 1,3-C4H6 or C4H5N/I radicals. These results will enrich the understanding of elevated pressure chemistry of 1,3-C4H6 and facilitate to further model development and validation focusing on a more detailed description of the formation network of aromatic compounds.

Measurements of Laminar Burning Velocities of Alternative Fuels: Application in Transport and Aerospace

The laminar burning velocity belongs to the fundamental combustion properties of fuels being a measure for their heat release, flame length, as well as reactivity and combustion stability, and thus, may impact the design of burners and combustion chambers. Also, these experimental data are needed for the validation and optimization within the construction and development of detailed chemical kinetic reaction mechanisms. Within this study, an overview of the different applications of fuel characterization regarding the specific area of interest (road transport, aviation, and aerospace) will be given. Depending on the application, effects of different molecular characteristics on the laminar burning velocity are evaluated: the presence of oxygen atoms and the grade of branching in a specific fuel molecule as well as the difference in the type of a chemical bond, here, single and double bonds. Examples of alternative fuels being discussed in the present study are: (I) oxymethylene ether (OMEn) in the field of road transport; (II) a paraffinic Alcohol-to-Jet fuel as sustainable aviation fuel; and (III) mixtures of ethane or ethene with nitrous oxide as green propellants for rocket propulsion applications.

Prediction of homogeneous combustion by modification of the fuel combustion mechanism in a DME fueled CI engine

This study was performed to predict numerically the homogeneous combustion characteristics where the fuel combustion mechanism was modified in a DME fueled CI engine. To achieve this, detailed chemical kinetic reaction mechanisms were used for the prediction of homogeneous combustion of hydrocarbon fuels (diesel and DME). The results were compared in terms of cylinder pressure, heat release rate, and CO and NOX emissions. Calculations were performed using the detailed chemical kinetic mechanism, including 671 species and 2933 reactions for n-heptane (n-C7H16) and 96 species and 453 reactions for dimethyl ether (CH3OCH3). In addition, a modified NOX mechanism was added to investigate the accumulated results of NOX production. The engine experiments were conducted using a single cylinder CI engine with a common-rail injection system. The fuel injection quantity was set to 8 mg, and the injection pressure was maintained at 50 MPa at 1500 RPM. In this study, DME and diesel fuels were injected for inducing the homogeneous combustion at BTDC 60 and BTDC 40 degree. The modified mechanism hardly affected the overall chemical reactions, which was almost identical in comparison to the results of the conventional mechanism. In addition, the ignition delay was slightly faster in the calculation of the n-heptane mechanism because it showed that a high reaction rate was involved in the fuel oxidation and reaction of the NTC region. The combustion and exhaust emission characteristics of the homogeneous combustion simulation were in good agreement with the engine experimental results at BTDC 60 degree of injection timing, but the CO emission was over predicted when the n-heptane mechanism was employed in the DME combustion simulation. The chemical reactions of the DME combustion process were dominated by the forward reaction, which were CH3OCH3+O→CH3OCH2+OH and CH3OCH3+OH→CH3OCH2+H2O reactions. Furthermore, this study confirmed that an increase of OH radicals promotes the fuel oxidation reaction, and it can influence the combustion temperature, which also affected the processes of NOX production and CO oxidation reactions.

Multi-fuel surrogate chemical kinetic mechanisms for real world applications.

The most important driving force for development of detailed chemical kinetic reaction mechanisms in combustion is the desire by researchers to simulate practical systems. This paper reviews the parallel evolution of kinetic reaction mechanisms and applications of those models to practical, real engines. Early, quite simple, kinetic models for small fuel molecules were extremely valuable in analyzing long-standing, poorly understood applied ignition and flame quenching problems, and later kinetic models have been applied to much more complex flame propagation, problems including autoignition in spark-ignition engines and issues related to octane numbers and knock in modern, high compression ratio and other engines. The recent emergence of very large, multi-fuel surrogate kinetic mechanisms that can address many different fuel types and real engine applications is discussed as a modern analytical tool that can be used for a wide variety of practical applications.

Effect of methane-hydrogen mixtures on flow and combustion of coherent jets

Coherent jets are widely used in electric arc furnace (EAF) steelmaking to increase the oxygen utilization and chemical reaction rates. However, the influence of fuel gas combustion on jet behavior is not fully understood yet. The flow and combustion characteristics of a coherent jet were thus investigated at steelmaking temperature using Fluent software, and a detailed chemical kinetic reaction mechanism was used in the combustion reaction model. The axial velocity and total temperature of the supersonic jet were measured via hot state experiments. The simulation results were compared with the experimental data and the empirical jet model proposed by Ito and Muchi and good consistency was obtained. The research results indicated that the potential core length of the coherent jet can be prolonged by optimizing the combustion effect of the fuel gas. Besides, the behavior of the supersonic jet in the subsonic section was also investigated, as it is an important factor for controlling the position of the oxygen lance. The investigation indicated that the attenuation of the coherent jet is more notable than that of the conventional jet in the subsonic section.

Modeling the effects of cosolvents on biodiesel production

In this study, a mathematical model is developed for predicting the effect of cosolvents on the biodiesel production, by taking into account the fact that the process consists of two liquid phases. The proposed model consists of a detailed chemical kinetic reaction mechanism and the phase equilibrium of the two phases. The experimental data for estimating the reaction rate constants consists of 1580 dynamic concentration data related to cosolvent-free systems. Then, the calculated reaction rate constants are used to model the biodiesel production process in systems containing cosolvents to investigate the cosolvent effects on the process. The average absolute relative deviation of 1.0% for all the experimental data points is a testament to the accuracy of the predictive model. Hence, the model was used to investigate the effect of methanol to oil ratio, the ratio of cosolvent to methanol, and the amount of catalyst on the biodiesel production rate and yield, in the presence of cosolvents tetrahydrofuran and diethyl ether. According to the results, the use of cosolvent leads to increase the reaction rates. In the other words, the process time is reduced; however, the final yield of biodiesel does not change. Comparison between two cosolvents shows that diethyl ether is more appropriate than tetrahydrofuran, because, in the use of diethyl ether, less cosolvent to methanol ratio is needed. Also, the effect of catalyst concentration is similar to the effect cosolvent.

Modeling plasma-assisted methane–air ignition using pre-calculated electron impact reaction rates

Development of practical combustion applications implementing plasma-assisted ignition technology for improved efficiency or fuel versatility will benefit from computationally-feasible models which include the plasma processes governing experimentally-observed combustion enhancement. A detailed chemical kinetic reaction mechanism for methane combustion with relevant plasma reactions has been compiled, including a set of electron impact cross sections for elastic and inelastic collisions with reactants, intermediate species, and products of methane combustion. In addition to electron impact reactions, the present mechanism includes reactions involving vibrationally- and electronically-excited species, dissociative recombination reactions, three-body recombination reactions, charge transfer reactions, and relaxation reactions, taken from the literature where available, and otherwise calculated using published correlations. While many past mechanisms have made assumptions limiting their use to specific regimes such as nanosecond discharges or microwave-enhanced flames, the present mechanism is generalized to include kinetics relating to both high- and low-energy excitation. The chemical kinetic mechanism is designed for use in a two-temperature chemical kinetics solver that tracks the electron temperature in addition to the gas temperature, as non-thermal plasma regimes characteristic to plasma-assisted combustion will typically have electron energies out of equilibrium with the energy of the heavier gas particles. Analysis considers the effects of initial temperature, mixture composition, electron concentration, and electric field strength on plasma ignition effectiveness. As commonly practiced, costly calculation of the Boltzmann equation at every time step is avoided by pre-calculating electron impact reaction rate coefficients using a Boltzmann equation solver. Here we evaluate the pre-calculated rates assumption, showing that ignition predictions depend on the gas composition at which the electron impact reaction rates are generated, but that induced errors are acceptable given the uncertainty in other model parameters such as impact cross sections. Finally, chemical kinetic sensitivity analysis highlights the importance of reactions governing free charge balance and nitrogen vibrational excitation when plasma effects on combustion enhancement are strong.

Chemical kinetics of octane sensitivity in a spark-ignition engine

This paper uses a chemical kinetic modeling approach to study the influences of fuel molecular structure on Octane Sensitivity (OS) in Spark Ignition (SI) engines. Octane Sensitivity has the potential to identify fuels that can be used in next-generation high compression, turbocharged SI engines to avoid unwanted knocking conditions and extend the range of operating conditions that can be used in such engines. While the concept of octane numbers of different fuels has been familiar for many years, the variations of their values and their role in determining Octane Sensitivity have not been addressed previously in terms of the basic structures of the fuel molecules. In particular, the importance of electron delocalization on low temperature hydrocarbon reactivity and its role in determining OS in engine fuel is described here for the first time. The role of electron delocalization on fuel reactivity and Octane Sensitivity is illustrated for a very wide range of engine fuel types, including n-alkane, 1-olefin, n-alcohol, and n-alkyl benzenes, and the unifying features of these fuels and their common trends, using existing detailed chemical kinetic reaction mechanisms that have been collected and unified to produce an overall model with unprecedented capabilities.

Experimental and Kinetic Modeling Study of 2-Methyl-2-Butene: Allylic Hydrocarbon Kinetics.

Two experimental studies have been carried out on the oxidation of 2-methyl-2-butene, one measuring ignition delay times behind reflected shock waves in a stainless steel shock tube, and the other measuring fuel, intermediate, and product species mole fractions in a jet-stirred reactor (JSR). The shock tube ignition experiments were carried out at three different pressures, approximately 1.7, 11.2, and 31 atm, and at each pressure, fuel-lean (ϕ = 0.5), stoichiometric (ϕ = 1.0), and fuel-rich (ϕ = 2.0) mixtures were examined, with each fuel/oxygen mixture diluted in 99% Ar, for initial postshock temperatures between 1330 and 1730 K. The JSR experiments were performed at nearly atmospheric pressure (800 Torr), with stoichiometric fuel/oxygen mixtures with 0.01 mole fraction of 2M2B fuel, a residence time in the reactor of 1.5 s, and mole fractions of 36 different chemical species were measured over a temperature range from 600 to 1150 K. These JSR experiments represent the first such study reporting detailed species measurements for an unsaturated, branched hydrocarbon fuel larger than iso-butene. A detailed chemical kinetic reaction mechanism was developed to study the important reaction pathways in these experiments, with particular attention on the role played by allylic C-H bonds and allylic pentenyl radicals. The results show that, at high temperatures, this olefinic fuel reacts rapidly, similar to related alkane fuels, but the pronounced thermal stability of the allylic pentenyl species inhibits low temperature reactivity, so 2M2B does not produce "cool flames" or negative temperature coefficient behavior. The connections between olefin hydrocarbon fuels, resulting allylic fuel radicals, the resulting lack of low-temperature reactivity, and the gasoline engine concept of octane sensitivity are discussed.

Kinetics of Oxidation of a 100% Gas-to-Liquid Synthetic Jet Fuel and a Mixture GtL/1-Hexanol in a Jet-Stirred Reactor: Experimental and Modeling Study

Research activities on the combustion of synthetic jet fuels and bioderived jet fuels have increased notably over the last 10 yr in order to solve the challenging reduction of dependence of air transportation on petroleum. Within the European Community's Seventh Framework Programme, the combustion of a 100% GtL from Shell and a 80/20% vol. GtL/1-hexanol blend were studied in a jet-stirred reactor (JSR). This synthetic GtL fuel mainly contains n-alkanes, iso-alkanes, and cyclo-alkanes. We studied the oxidation of these alternative jet fuels under the same conditions (temperature, 550–1150 K; pressure, 10 bar; equivalence ratio, 0.5–2; initial fuel concentration, 1000 ppm). For simulating the oxidation kinetics of these fuels we used a new surrogate mixture consisting of n-dodecane, 3-methylheptane, n-propylcyclohexane, and 1-hexanol. A detailed chemical kinetic reaction mechanism was developed and validated by comparison with the experimental results obtained in a JSR. The current model was also tested for the auto-ignition of the GtL fuel under shock tubes conditions (φ = 1 and P = 20 atm) using data from the literature. Kinetic computations involving reaction paths analyses and sensitivity analyses were used to interpret the results. The general findings are that the GtL and GtL/hexanol blend have very similar reactivity to Jet A-1, which is important since GtL is a drop-in fuel that should have similar performance to the Jet A-1 baseline and 1-hexanol should not significantly affect the reactivity if it is to be used as an additive.

Numerical simulation of micro-scale catalytic combustion characteristics with detailed chemical kinetic reaction mechanisms of hydrogen/air

Micro-scale catalytic combustion characteristics with detailed gas phase and surface catalytic reaction mechanisms of hydrogen/air were investigated numerically. Micro-combustion characteristics for different reaction models and the influence of wall thermal conductivity, inlet velocity, tube diameter on surface catalytic combustion reaction were discussed. The computational results indicate that the surface catalytic combustion restrains the gas phase combustion. The gas phase reaction inhibition by the catalyst is sensitive to thermal boundary condition at the wall. The gas phase reaction cannot be ignored inside a micro-scale catalyst combustor for most conditions. The higher wall temperature gradient for low wall thermal conductivity will promote the gas phase combustion shift upstream and will result in a higher temperature distribution. The micro-tube can be divided into two regions. The upstream region is dominated by the surface catalytic reaction and the downstream region is dominated by the gas phase combustion. With increasing inlet velocity, the region dominated by surface catalytic reactions expanded downstream and finally occupied the whole micro-tube. The temperature of the flame core decreases with the decrease of tube diameter. Decreasing the tube diameter will enhance the surface catalytic reactions. Inside a micro-catalytic combustor, the effect of surface catalytic reaction on gas phase reaction can be divided into three characteristic reaction types.

Experimental and detailed kinetic model for the oxidation of a Gas to Liquid (GtL) jet fuel

The kinetics of oxidation, ignition, and combustion of Gas-to-Liquid (GtL) Fischer–Tropsch Synthetic kerosene as well as of a selected GtL-surrogate were studied. New experimental results were obtained using (i) a jet-stirred reactor – species profiles (10bar, constant mean residence time of 1s, temperature range 550–1150K, equivalence ratios φ=0.5, 1, and 2), (ii) a shock tube – ignition delay time (≈16bar, temperature range 650–1400K, φ=0.5 and 1), and (iii) a burner – laminar burning velocity (atmospheric pressure, preheating temperature=473K, 1.0⩽φ⩽1.5). The concentrations of the reactants, stable intermediates, and final products were measured as a function of temperature in the jet-stirred reactor (JSR) using probe sampling followed by on-line Fourier Transformed Infra-Red spectrometry, and gas chromatography analyses (on-line and off-line). Ignition delay times behind reflected shock waves were determined by measuring time-dependent CH* emission at 431nm. Laminar flame speeds were obtained in a bunsen-type burner by applying the cone angle method. Comparison with the corresponding results for Jet A-1 showed comparable combustion properties. The GtL-fuel oxidation was modeled under these conditions using a detailed chemical kinetic reaction mechanism (8217 reactions vs. 2185 species) and a 3-component model fuel mixture composed of n-decane, iso-octane (2,2,4-trimethyl pentane), and n-propylcyclohexane. The model showed good agreement with concentration profiles obtained in a JSR at 10bar. In the high temperature regime, the model represents well the ignition delay times for the fuel air mixtures investigated; however, the calculated delays are longer than the measurements. It was observed that the ignition behavior of the surrogate fuel is mainly influenced by n-alkanes and not by the addition of iso-alkanes and cyclo-alkanes. The simulated laminar burning velocities were found in excellent agreement with the measurements. No deviation between burning velocity data for the GtL-surrogate and GtL was seen, within the uncertainty range. The presented data on ignition delay times and burning velocities agree with earlier results obtained for petrol-derived jet fuel. The suitability of both the current detailed reaction model and the selected GtL surrogate was demonstrated. Finally, our results support the use of the GtL fuel as an alternative jet fuel.

Laminar Burning Velocities of C4–C7 Ethyl Esters in a Spherical Combustion Chamber: Experimental and Detailed Kinetic Modeling

To better understand the combustion characteristics of ethyl esters that could become second-generation biofuels, new experimental data were obtained for the combustion of a series of small ethyl esters. Unstretched laminar burning velocities of C4–C7 ethyl ester–air premixed laminar flames were measured in a spherical combustion chamber over a range of pressures (1–10 bar), initial temperatures (323–473 K), and equivalence ratios (0.7–1.5). These experiments were simulated as well as low-pressure flame structures, jet-stirred reactor species profiles, and ignition delays in shock tubes and rapid compression machines. A new detailed chemical kinetic reaction mechanism (1845 reactions versus 232 species) was developed and used in this work. The present model shows good agreement with the present experimental data and those taken from the literature. To interpret the results, sensitivity analyses were performed.

Influence of ozone on the combustion of n-heptane in a HCCI engine

Homogeneous charge compression ignition (HCCI) experiments were performed in a single-cylinder diesel engine fueled with n-heptane at constant equivalence ratio of 0.3, intake temperature of 300K, and engine speed of 1500rpm. The intake manifold was seeded by ozone produced by a dielectric barrier discharge reactor with a wire–cylinder configuration. Experimental results showed that low ozone concentrations, i.e., <50ppm, have an important impact on the phasing of the cool and main flame in the engine. To interpret the engine results, the modeling of constant volume combustion at 20 and 40bars was performed using a detailed chemical kinetic reaction mechanism. The kinetic modeling indicated that the fuel starts to oxidize via reaction with O-atoms produced by ozone decomposition (n-C7H16+O→C7H15+OH) and that the ozone-accelerated production of OH speed up both cool and main flame. The production of O-atoms by decomposition of ozone during the compression stroke could be a way to control, cycle to cycle, two stage ignition fuels of HCCI engine.

Experimental and Numerical Study of F-T/Biodiesel/Bioethanol Surrogate Fuel Oxidation in Jet-Stirred Reactor

Blends of Fischer–Tropsch (F-T) fuels, biodiesel, and ethanol seem to be a promising fuel for compression ignition (CI) engine applications. An advanced control of current diesel engines requires a detailed comprehension of the fuel chemistry in terms of auto-ignition and pollutant formation. However, neither experimental data, nor convenient combustion models are available for such an alternative fuel. Therefore, the kinetics of oxidation of F-T, F-T/biodiesel, and F-T/biodiesel/bioethanol surrogate fuel (n-decane, iso-octane, methyl octanoate, and ethanol) were studied experimentally in a jet-stirred reactor (JSR) at 10 atm and constant residence time of 1 s, over the temperature range of 560–1160 K, and for several equivalence ratios (0.5–2.0). The oxidation of these fuels was modeled using a detailed chemical kinetic reaction mechanism consisting of 9919 reactions and 2202 species. The proposed kinetic reaction mechanism yields a good representation of the kinetics of oxidation of the tested biofuel blends. Supplemental materials are available for this article. Go to the publisher's online edition of Combustion Science and Technology to view the free supplemental file.

Photoionization mass spectrometry and modeling study of premixed flames of three unsaturated C5H8O2 esters

The detailed chemical structures of low-pressure premixed laminar flames fueled by three simple unsaturated C5H8O2 esters, the methyl crotonate (MC), methyl methacrylate (MMA), and ethyl propenoate (EPE), are investigated using tunable synchrotron vacuum ultraviolet (VUV) photoionization mass spectrometry. Significant differences in the compositions of key reaction intermediates between these flames under similar flame conditions are observed. The results enable further refinement and validation of a detailed chemical kinetic reaction mechanism, which is largely based on a previous model for saturated esters. Detailed kinetic modeling describes how these differences are related to molecular structures, leading to unique fuel destruction pathways for each of these isomers. Meanwhile, the effect of carbon carbon double bonds on the combustion chemistry of small fatty acid esters is addressed.

Detailed chemical kinetic modeling of the effects of C[dbnd]C double bonds on the ignition of biodiesel fuels

A detailed chemical kinetic reaction mechanism previously developed to study combustion of soy and rapeseed oil methyl ester biodiesel fuels is used to simulate combustion of many other biodiesel fuels derived from different vegetable oils and animal fats. All of these biodiesel fuels consist of unique mixtures of the same five individual, single-component methyl esters, including methyl stearate, methyl oleate, methyl linoleate, methyl linolenate, and methyl palmitate. The stearate and palmitate molecules are saturated, while the oleate, linoleate and linolenate have one, two and three CC double bonds, respectively. Each plant- or fat-derived biodiesel fuel that is made from the same five components has variations in combustion properties that depend on differences in the relative fractions of these five components. The present study focuses on ignition properties of these oil- and fat-derived biodiesel fuels and on their cetane numbers (CN), which measure relative ignition rates under diesel engine operating conditions. A key factor determining differences in ignition properties and CN of the many methyl ester diesel fuels is shown to be the number of CC double bonds in the long carbon chains of each component molecule, with each CC double bond reducing the CN value by a significant amount. Each CC double bond provides allylic sites where H atoms are easily abstracted, but these allylic radical sites are shown to be weak bonding sites for molecular oxygen that do not support subsequent isomerization reactions that lead to low temperature reactivity and ignition. This reduced rate of low temperature reactivity is responsible for the reductions in CN due to the presence of these CC double bonds. The amount of reduction in low temperature reactivity is roughly proportional to the number of CC double bonds in each biodiesel fuel molecule, relative to the saturated components of biodiesel fuel.

The Effect of Carbon–Carbon Double Bonds on the Combustion Chemistry of Small Fatty Acid Esters

Abstract Environmentally friendly biodiesel is a mixture of saturated and unsaturated methyl (or ethyl) esters of long-chain fatty acids. To experimentally examine the effect of C=C double bonds on the combustion chemistry of fatty acid esters, low-pressure premixed laminar flames of four small esters have been studied using flame-sampling molecular-beam mass spectrometry. Mole fraction profiles of reactants, products, and well-identified stable and reactive combustion intermediates in flames of the saturated species methyl propanoate (CH3CH2COOCH 3) and its isomer ethyl acetate (CH3COOCH2CH 3) have been compared with results from flames of the unsaturated fuels methyl propenoate (CH2CHCOOCH 3) and vinyl acetate (CH3COOCHCH 2) flames. A total of eight flames have been studied, with two fuel-rich flame conditions investigated (fuel-equivalence ratios φ=1.2 and 1.56) for each fuel. In addition, the underlying oxidation chemistry at these premixed flame conditions has been investigated using a detailed chemical kinetic reaction mechanism, which is largely based on a previously proposed model for saturated esters [B. Yang et al., Phys. Chem. Chem. Phys. 13 (2011) 7205]. The combined results provide a detailed understanding of the similarities and differences between the combustion of saturated vs. unsaturated esters. Meanwhile, the isomeric and stoichiometric effects on their combustion chemistry are also addressed. In this paper, experimental and modeling details are discussed with a special focus on the different reaction pathways.

Experimental and Detailed Kinetic Modeling Study of Isoamyl Alcohol (Isopentanol) Oxidation in a Jet-Stirred Reactor at Elevated Pressure

Isoamyl alcohol (isopentanol or 3-methylbutan-1-ol) that can be biologically produced is among the possible alcohols usable as an alternative fuel in internal combustion engines. It has a higher energy density than smaller alcohols (ca. 28.5 MJ/L, as compared to ca. 21 MJ/L for ethanol and 27 MJ/L for 1-butanol). It is less hydroscopic than ethanol and mixes better with hydrocarbons. To better understand the combustion characteristics of that alcohol, new experimental data were obtained for its kinetics of oxidation in a jet-stirred reactor (JSR). Concentration profiles of stable species were measured in a JSR at 10 atm over a range of equivalence ratios (0.35−4) and temperatures (530−1220 K). The oxidation of isopentanol was modeled using an extended detailed chemical kinetic reaction mechanism (2170 reactions involving 419 species) derived from a previously proposed scheme for the oxidation of a variety of fuels. The proposed mechanism shows good agreement with the present experimental data. Reaction pa...

Modeling Study of Hydrogen/Oxygen andn-alkane/Oxygen Counterflow Diffusion Flames

A comprehensive analysis of hydrogen/oxygen and hydrocarbon/oxygen counterflow diffusion flames has been conducted using corresponding detailed reaction mechanisms. The hydrocarbon fuels contain n-alkanes from CH4 to C16H34. The basic diffusion flame structures are demonstrated, analyzed, and compared. The effects of pressure, and strain rate on the flame behavior and energy-release rate for each fuel are examined systematically. The detailed chemical kinetic reaction mechanisms from Lawrence Livermore National Laboratory (LLNL) are employed, and the largest one of them contains 2115 species and 8157 reversible reactions. The results indicate for all of the fuels the flame thickness and heat release rate correlate well with the square root of the pressure multiplied by the strain rate. Under the condition of any strain rate and pressure, H2 has thicker flame than hydrocarbons, while the hydrocarbons have the similar temperature and main products distributions and almost have the same flame thickness and heat release rate. The result indicates that the fuels composed with these hydrocarbons will still have the same flame properties as any pure n-alkane fuel.