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The oxidation of di-isopropyl-ether (DIPE) was studied in a jet-stirred reactor. Fuel-lean, stoichiometric, and fuel-rich mixtures (φ = 0.5–4) were oxidized at a constant fuel mole fraction of 1000 ppm, at temperatures ranging from 500 to 1160 K, at 10 atm, and constant residence time of 0.7 s. The chosen conditions are consistent with our previous studies on ether oxidation. Mole fraction profiles were obtained through sonic probe sampling, and analyzed by gas chromatography and Fourier transform infrared spectrometry. As opposed to our previous studies on ethers (S. Thion et al. 2017, Z. Serinyel et al. 2018 and 2020), DIPE showed no low-temperature reactivity under the same experimental conditions. Oxidation of the rich mixture showed similarities to pyrolysis producing important quantities of propene and isopropanol, while no isopropanol is observed under lean conditions. In terms of overall reactivity, DIPE showed smaller fuel conversion compared to other symmetric ethers previously studied. The present data and literature experiments were simulated with our ether oxidation mechanism showing good agreement. [ABSTRACT FROM AUTHOR]

The oxidation of diethyl ether was studied experimentally in a jet-stirred reactor. Fuel-lean, stoichiometric and fuel-rich mixtures were oxidized at a constant fuel mole fraction (1000 ppm), at temperatures ranging from 450 to 1250 K, pressures of 1 and 10 atm, and constant residence time (70 and 700 ms, respectively). In total, six mixtures were tested at both pressures. Mole fraction profiles were obtained using gas chromatography and Fourier transform infrared spectrometry. The fuel mole fraction profiles, as well as some reaction intermediate and product profiles indicated strong low-temperature chemistry at high pressure. On the other hand, at atmospheric pressure this behavior was observed to a very small extent and only with the lean and stoichiometric mixtures. These data were compared to modeling results using literature mechanisms for diethyl ether oxidation. None of these predicted low-temperature reactivity under present conditions. Therefore, a kinetic mechanism is proposed in this study, based on recently computed kinetic parameters from literature. It shows good performances for representing the present experimental data as well as experimental data found in literature consisting of ignition delay times, laminar flame speeds and flame structure. [ABSTRACT FROM AUTHOR]

The kinetics of cyclohexanone oxidation was studied in a jet-stirred reactor (JSR) at atmospheric pressure, over the temperature range 740–1250 K, and for equivalence ratios of φ = 1 and 2 and a residence time of 70 ms. Concentration profiles of reactants, stable intermediates and products were measured by gas chromatography (GC) and Fourier transform infrared spectrometry (FTIR) after sonic probe sampling. Reaction intermediates measured during oxidation are mainly: methane, ethane, ethylene, propene, cyclohex-2-en-1-one and methyl vinyl ketone. To a less extent, cyclic intermediates such as cyclopentene, 1,3-cyclopentadiene were also detected. These new data complete those obtained by Serinyel et al. [1] through jet-stirred reactor experiments performed at 10 atm. Moreover, in this study, rate constants of important reactions were calculated at the G3//MP2/aug-cc-pvdz level of theory with strict convergence criterion. These rate constants involve hydrogen abstraction reactions from the fuel by H, OH, and CH 3 radicals, decomposition and isomerization reactions of the fuel radicals. The resulting kinetic mechanism was tested against all the available JSR data with satisfactory agreement. [ABSTRACT FROM AUTHOR]

In an effort to understand the oxidation chemistry of new generation biofuels, oxidation of a pentanol isomer (2-methyl-1-butanol) was investigated experimentally in a jet-stirred reactor (JSR) at a pressure of 10 atm, equivalence ratios of 0.5, 1, 2 and 4 and in a temperature range of 700–1200 K. Concentration profiles of the stable species were measured using GC and FTIR. A detailed chemical kinetic mechanism including oxidation of various hydrocarbon and oxygenated fuels was extended to include the oxidation chemistry of 2-methyl-1-butanol, the resulting mechanism was used to simulate the present experiments. In addition to the present data, recent experimental data such as ignition delay times measured in a shock tube and laminar flame speeds were also simulated with this mechanism and satisfactory results were obtained. Reaction path and sensitivity analyses were performed in order to interpret the results. [ABSTRACT FROM AUTHOR]

The oxidation of di-n-propyl-ether (DPE), was studied in a jet-stirred reactor. Fuel-lean, stoichiometric and fuel-rich mixtures (φ = 0.5–4) were oxidized at a constant fuel mole fraction of 1000 ppm, at temperatures ranging from 470 to 1160 K, at 10 atm, and constant residence time of 700 ms. The mole fraction profiles were obtained through sonic probe sampling and gas chromatography and Fourier transform infrared spectrometry analyses. As was the case in our previous studies on ethers (diethyl ether and di-n-butyl ether), the carbon neighboring the ether group was found to be the most favorable site for H-abstraction reactions and the chemistry of the corresponding fuel radical drives the overall reactivity. The fuel concentration profiles indicated strong low-temperature chemistry. A kinetic sub-mechanism is developed based on rules similar to those for the two symmetric ethers previously investigated (DEE and DBE). The proposed mechanism shows good performances in representing the present experimental data, nevertheless, more data such as atmospheric pressure speciation will be needed in order to better interpret the kinetic behavior of DPE. [ABSTRACT FROM AUTHOR]

The oxidation of dibutyl-ether, a potential lignocellulosic biofuel was studied in a jet-stirred reactor. Fuel-lean, stoichiometric and fuel-rich mixtures were oxidized at a constant fuel mole fraction (1000 ppm), at temperatures ranging from 470 to 1250 K, pressures of 1 and 10 atm, and constant residence time (70 and 700 ms, respectively). The mole fraction profiles obtained through sonic probe sampling, gas chromatography and Fourier transform infrared spectrometry were used to develop a detailed kinetic mechanism for the oxidation of DBE. The carbon neighboring the ether group was found to be the most favorable site for H-abstraction reactions and the chemistry of the corresponding fuel radical drives the overall reactivity. The fuel concentration profiles indicated strong low-temperature chemistry at both pressures: two negative temperature coefficient regions were observed, notably on the 10 atm experiments. This unusual behavior was investigated by means of a rate of production analysis using the mechanism developed in this work. This analysis showed that the low-temperature reactivity stems from the low-temperature chemistry of the fuel and of smaller species such as C 4 H 9 which are triggered at different threshold temperatures. The proposed mechanism shows good performances for representing the present experimental data, as well as ignition delay time and flame speed data available from the literature. [ABSTRACT FROM AUTHOR]

Null [ABSTRACT FROM AUTHOR]

Abstract: Laminar flame speed measurements of dimethyl ether/air mixtures were made at 1, 5, and 10atm with equivalence ratios ranging from 0.7 to 1.6. All experiments were performed in a large cylindrical constant-volume bomb with optical access. A new method for converting flame images into flame radii was used. Results reported in other studies were investigated, and some explanations on the disparities found are presented. A full uncertainty analysis was performed combining precision errors from data scatter with predicted systematic errors. Uncertainties ranging between 4.2% and 8.6% were found depending on the equivalence ratio and initial pressure. Experimental results agreed well with some other spherical flame experiments and counterflow flame measurements, but were found to be much lower than PIV-based stagnation flame results. Also, two spherical flame studies deviated significantly both in magnitude and trend. Critical radii and Peclet numbers, defined by the onset of rapid flame acceleration, were recorded for all high-pressure experiments. Markstein lengths were measured and showed a decreasing trend with increasing equivalence ratio. Three different methods were used to define the laminar flame thickness, and large disparities were found between them. In this study, the modeled temperature gradient method for the definition of flame thickness is preferred over other methods. Modeling was performed with the latest version of a C3 chemical kinetics mechanism. Good agreement is seen between the experimental results and the model at all pressures. Emphasis is placed in this paper on reporting experimental uncertainties, calculated density ratios, flame temperatures, and flame radii ranges used for data analysis, and the results resolve some discrepancies seen in the literature for dimethyl ether flame speeds. [ABSTRACT FROM AUTHOR]

Di-isobutylene has received significant attention as a promising fuel blendstock, as it can be synthesized via biological routes and is a short-listed molecule from the Co-Optima initiative. Di-isobutylene is also popularly used as an alkene representative in multi-component surrogate models for engine studies of gasoline fuels. However, there is limited experimental data available in the literature for neat di-isobutylene under engine-like conditions. Hence, most existing di-isobutylene models have not been extensively validated, particularly at lower temperatures (< 1000 K). Most gasoline surrogate models include the di-isobutylene sub-mechanism published by Metcalfe et al. [1] with little or no modification. The current study is undertaken to develop a detailed kinetic model for di-isobutylene and validate the model using a wide range of relevant experimental data. Part 1 of this study exclusively focuses on the low- to intermediate temperature kinetics of di-isobutylene. An upcoming part 2 discusses the high-temperature model development and validation of the relevant experimental targets. Ignition delay time measurements for the di-isobutylene isomers were performed at pressures ranging from 15 – 30 bar at equivalence ratios of 0.5, 1.0, and 2.0 diluted in air and in the temperature range 650 – 900 K using two independent rapid compression machine facilities. In addition, measurements of species identified during the oxidation of these isomers were performed in a jet-stirred reactor and in a rapid compression machine. A detailed kinetic model for the di-isobutylene isomers is developed to capture the wide range of new experimental targets. For the first time, a comprehensive low-temperature chemistry submodel is included. The differences in the important reaction pathways for the accurate prediction of the oxidation of the two DIB isomers are compared using reaction path analysis. The most sensitive reactions controlling the ignition delay times of the DIB isomers under the pressure and temperature conditions necessary for autoignition in engines are identified. [ABSTRACT FROM AUTHOR]

The development of accurate chemical kinetic models capable of predicting the combustion of methane and dimethyl ether in common combustion environments such as compression ignition engines and gas turbines is important as it provides valuable data and understanding of these fuels under conditions that are difficult and expensive to study in the real combustors. In this work , both experimental and chemical kinetic model-predicted ignition delay time data are provided covering a range of conditions relevant to gas turbine environments ( T = 600–1600 K, p = 7–41 atm, ϕ = 0.3, 0.5, 1.0, and 2.0 in ‘air’ mixtures). The detailed chemical kinetic model (Mech_56.54) is capable of accurately predicting this wide range of data, and it is the first mechanism to incorporate high-level rate constant measurements and calculations where available for the reactions of DME. This mechanism is also the first to apply a pressure-dependent treatment to the low-temperature reactions of DME. It has been validated using available literature data including flow reactor, jet-stirred reactor, shock-tube ignition delay times, shock-tube speciation, flame speed, and flame speciation data. New ignition delay time measurements are presented for methane, dimethyl ether, and their mixtures; these data were obtained using three different shock tubes and a rapid compression machine. In addition to the DME/CH 4 blends, high-pressure data for pure DME and pure methane were also obtained. Where possible, the new data were compared with existing data from the literature, with good agreement. [ABSTRACT FROM AUTHOR]