Jean-Claude Boettner

A WIDE RANGE MODELING STUDY OF DIMETHYL ETHER OXIDATION

A detailed chemical kinetic model has been used to study dimethyl ether (DME) oxidation over a wide range of conditions. Experimental results obtained in a jet-stirred reactor (JSR) at I and 10 atm, 0.2 < 0 < 2.5, and 800 < T < 1300 K were modeled, in addition to those generated in a shock tube at 13 and 40 bar, 0 = 1.0 and 650 :5 T :5 1300 K. The JSR results are particularly valuable as they include concentration profiles of reactants, intermediates and products pertinent to the oxidation of DME. These data test the Idnetic model severely, as it must be able to predict the correct distribution and concentrations of intermediate and final products formed in the oxidation process. Additionally, the shock tube results are very useful, as they were taken at low temperatures and at high pressures, and thus undergo negative temperature dependence (NTC) behavior. This behavior is characteristic of the oxidation of saturated hydrocarbon fuels, (e.g. the primary reference fuels, n-heptane and iso- octane) under similar conditions. The numerical model consists of 78 chemical species and 336 chemical reactions. The thermodynamic properties of unknown species pertaining to DME oxidation were calculated using THERM.

A jet-stirred reactor for kinetic studies of homogeneous gas-phase reactions at pressures up to ten atmospheres (≈1 MPa)

An homogeneous stirred reactor designed for kinetic studies of hydrocarbon oxidation in the intermediate temperature range is described. The originality of this reactor lies in its ability to operate under pressure up to 10 atm ( approximately 1 MPa). The design of the injectors makes it possible to move a thermocouple and a sampling probe throughout a whole diameter of the reactor.

Kerosene combustion at pressures up to 40 atm: Experimental study and detailed chemical kinetic modeling

The oxidation of TR0 kerosene (jet A1 aviation fuel) was studied in a jet-stirred reactor (JSR) at pressures extending from 10 to 40 atm, in the temperature range 750–1150 K. A large number of reaction intermediates were identified, and their concentrations were followed for reaction yields ranging from low conversion to the formation of the final products. A reference hydrocarbon, n-decane, studied under the same experimental conditions gave very similar experimental concentration profiles for the main oxidation products. Because of the strong analogy between n-decane and kerosene oxidation kinetics, a detailed chemicalkinetic reaction mechanism describing the oxidation of n-decane was built to reproduce the present experimental results. This mechanism includes 573 elementary reactions, most of them being reversible, among 90 chemical species. A reasonably good prediction of the concentrations of major species was obtained by computation, covering the whole range of temperatures, pressures, and equivalence ratios of the experiments. A kinetic analysis performed to identify the dominant reaction steps of the mechanism shows that, underthe conditions of the present study (intermediate temperature and high pressure), HO2 radicals are important chain carriers leading to the formation of the branching agent H2O2.

Chemical kinetic study of dimethylether oxidation in a jet stirred reactor from 1 to 10 ATM: Experiments and kinetic modeling

The oxidation of dimethyl ether (DME) has been studied in a jet-stirred reactor (JSR). The experiments cover a wide range of conditions: 1–10 atm, 0.2≤≤2.0, 800–1300 K. Concentration profiles of reactants, internediates, and products of the oxidation of DME were measured in a fused silica JSR by low-pressure, sonic-probe sampling and off-line gas chromatography analyses. These results represent the first detailed kinetic study of DME oxidation in a reactor. They demonstrate that the oxidation of DME does not yield higher molecular weight compounds. A numerical model consisting of a detailed kinetic-reaction mechanism with 286 reactions (most of them reversible) among 43 species describes DME oxidation in a JSR. A generally good agreement between the data and the model was observed. The kinetic modeling is used to interpret the data.

Methane Oxidation: Experimental and Kinetic Modeling Study

Abstract Methane oxidation in jet-stirred reactor has been investigated at high temperature (900–1300 K) in the pressure range 1–10 atm. Molecular species (H2, CO, C02, CH4. C2,H2, C2H4, C2,H6) concentration profiles were obtained by probe sampling and GC analysis. Methane oxidation was modeled using a detailed kinetic reaction mechanism including the most recent kinetic findings concerning the reactions involved in the oxidation of C1,-C4 hydrocarbons. The proposed mechanism is able to reproduce experimental data obtained in our high-pressure jet stirred reactor and ignition delay times measured in shock tube in the pressure range 1–13 atm, for temperatures extending from 900 to 2000 K and equivalence ratios of 0.1 to 2. It is able to correctly reproduce H and O atoms concentrations measured in shock tube at ≈ 2 atm at 1850–2500 K. The same kinetic mechanism can also be used to model the oxidation of ethylene, ethane, propyne and allene in various conditions.

Experimental study and modeling of kerosene oxidation in a jet-stirred flow reactor

The oxidation of a kerosene fuel and of a mixture of 3 hydrocarbons (79% n-undecane—10% n-propylcyclohexane—11% 1,2,4-trimethylbenzene) was studies in a jet-stirred flow reactor in the temperature range 873–1033 K at atmospheric pressure. The concentrations of molecular species were measured at different extents of reaction by gas chromatography. The reaction products formed during the oxidation of the kerosene and the ternary mixture were identical. The main hydrocarbon intermediates were ethylene, propene, methane, 1-butene, 1,3-butadiene and ethane. Several other unsaturated hydrocarbon were also detected as minor products: 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene and 1-dencene and also 1,3-pentadiene, cyclopentadiene, benzene, toluene and xylene. In both experiments, the concentration profiles of molecular species were very similar, indicating that the mixture of 3 hydrocarbons from C9 to C11 belonging to 3 different chemical families (n-alkanes, cyclanes and aromatics) is representative of the kerosene studied. On the basis of the experimental observation of a low concentration level for large hydrocarbon intermediates, quasi-global chemical kinetic reaction mechanisms were developed to reproduce the experimental data. These models involve a few global molecular reactions for the oxidation-pyrolysis of the initial fuel molecules and a detailed mechanism for the oxidation of the small intermediate hydrocarbons.

Experimental and Kinetic Modeling Study of Cyclohexane Oxidation in a JSR at High Pressure

Cyclohexane oxidation has been studied in a jet-stirred reactor in the temperature range of 750 to 1100 K. at 10 atm. Major and minor species profiles have been obtained by probe sampling and GC analysis. A chemical kinetic reaction mechanism developed from previous studies on smaller hydrocarbons is used to reproduced the experimental data. It has been updated and validated for CI to C5 submechanisms. Good agreement is obtained between computed and measured mole fractions. The major reaction paths of cyclohexane consumption and the formation and the consumption routes of the main products have been identified for our experimental conditions.

Kinetic Study of N-Pentane Oxidation

Abstract The oxidation of H-pentane is studied in a jet-stirred flow reactor in the temperature range 950-1050K at atmospheric pressure for a wide range of fuel-oxygen equivalence ratios (0.2 to 2.0). A chemical kinetic reaction mechanism developed from previous studies on smaller hydrocarbons and extended to C5 species is used to reproduce the experimental data. Good agreement between computed and measured concentrations of major chemical species is obtained for the entire range of experimental conditions. The major reaction paths for H-pentane consumption and for the formation of the main products are identified. The same mechanism is used to model experiments performed by other investigators on n-pentane oxidation in reactors or in a shock tube. The experimental concentration profiles of the chemical species in a jet-stirred reactor between 1000 and 1250 K. are closely reproduced, as well as the ignition delays measured behind a reflected shock wave up to 1400K.

Chemical kinetic modeling of the supercritical-water oxidation of methanol

Abstract The kinetics of the supercritical oxidation of methanol was modeled using a detailed chemical kinetic reaction mechanism initially validated for the supercritical-water oxidation of hydrogen, carbon monoxide, and methane. The concentration profiles of reactants and products measured in a plug flow reactor at MIT have been used to validate a detailed kinetic reaction mechanism in supercritical conditions.

Oxidation and Ignition of Methane-Propane and Methane-Ethane-Propane Mixtures: Experiments and Modeling

Abstract The kinetics of the oxidation of natural gas blends (CH4/C3H8 and CH4/C2H6/C3H8) has been studied in a jet stirred reactor (900 < T/K < 1230, 1 < P/atm < 10, 0.1 < equivalence ratio < 1.5). Mole fractions of reactants, intermediates and products have been measured in a JSR as a function of temperature and mean residence time. These results have been used to validate a detailed kinetic reaction mechanism. Literature ignition delay times of CH4/C3H8/O2 mixtures measured in shock tube have also been modeled. A general good agreement between the data and the model is found. The same mechanism has also been used to sucessfully represent the oxidation of methane, ethyne, ethene, ethane, propene, and propane in various conditions including JSR, shock tube and flame. The present study clearly shows the importance of traces of ethane and propane on the oxidation of methane. The computations indicate that the oxidation of methane is initiated by its reaction with O2 and by thermal dissociation when no othe...