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Cyclopentane (C5H10) and tetrahydrofuran (C4H8O) are both five‐membered ring compounds. The present study compares the auto‐ignition of cyclopentane and tetrahydrofuran in a high‐pressure shock‐tube (20 atm). Twelve different mixtures were investigated at two different fuel initial mole fractions (1% and 2%): at Xfuel = 1%, three equivalence ratios, kept constant between cyclopentane and tetrahydrofuran, were studied (0.5, 1, and 2), whereas three Xfuel/XO2 were investigated when Xfuel = 2%. A detailed kinetic mechanism was developed to reproduce cyclopentane and tetrahydrofuran auto‐ignition. The agreement between our experimental results and the modeling is very good. This mechanism was used to explain the similarities and differences observed between cyclopentane and tetrahydrofuran auto‐ignition. [ABSTRACT FROM AUTHOR]

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 esters has been extensively studied over the past 15 years, mainly focusing on methyl‐ and ethyl‐esters. Recently, the oxidation of esters produced from higher alcohols has received more and more attention. In this work, we report experiments and modeling on the oxidation of a series of four esters with five carbon atoms, namely, methyl butanoate, ethyl propanoate, propyl acetate, and butyl formate. The oxidation of these esters was performed in a jet‐stirred reactor under the same experimental conditions (τ = 700 ms, p = 10 atm, φ = 1, and Xfuel, initial = 1000 ppm). The mole fraction profiles obtained from these experiments were used to develop a unique detailed kinetic mechanism for the oxidation of these four esters, which performs well against our experimental data and on data from the literature. Although these esters are isomers, this work highlights the influence of the position of the ester function in terms of global reactivity and product distribution. In particular, this comparison shows the strong impact of the nature of the products (i.e., acid + alkene) formed by the different molecular decomposition reactions during the oxidation process of these esters. [ABSTRACT FROM AUTHOR]

The modern catalytic or enzymatic advances allow the production of novel biofuel. Among them, 1,3-dioxolane can be produced from formaldehyde and ethylene glycol, both can be obtained from biomass. In this study, the oxidation of 1,3-dioxolane is studied at stoichiometric conditions. The ignition delay times of 1,3-dioxolane/O 2 /inert mixtures were measured in a shock tube and in a rapid compression machine at pressures of 20 to 40 bar and temperatures ranging from 630 to 1300 K. The pressure profiles recorded in the rapid compression machine show a first stage of ignition enlightening the influence of the low temperature chemistry of combustion. Furthermore, mole fraction profiles of the stable intermediates produced during the oxidation of 1,3-dioxolane were measured in a jet-stirred reactor at 10 bar. Following these observations, a detailed kinetic model was developed with reaction rate coefficients and thermochemical data calculated by theoretical calculations or estimated by analogies to suitable molecules. In order to get an insight into the most important reaction pathways brute force sensitivity analysis and reaction pathway analysis were performed with the proposed model and discussed. It became clear that in the fuel-in-air case for the alkylhydroperoxide of 1,3-dioxolane the ring opening beta-scission pathway is favored against the further alkane-like second addition to molecular oxygen, which leads to a limited negative temperature coefficient. [ABSTRACT FROM AUTHOR]

The oxidation of pentan-2-ol was investigated at high-pressure in a jet-stirred reactor and in a shock tube. Experiments in the JSR were carried out at 10 atm, between 500 and 1180 K, for five different equivalence ratios of φ = 0.35, 0.5, 1, 2, 4 and 1000 ppm of fuel, at a constant residence time of 0.7 s. Reactant, product and intermediate species mole fractions were quantified using Fourier transform infrared spectrometry (FTIR) and gas chromatography (GC). Ignition delay times were measured for pentan-2-ol/O 2 mixtures in argon in a shock tube at 20 and 40 bar, in a temperature range of 1070–1460 K and for equivalence ratios of φ = 0.5, 1 and 2. Ignition delay times of a stoichiometric mixture were also measured in air at 20 bar. Under these conditions, this alcohol exhibited no low-temperature reactivity in either experimental set-ups. Based on ab initio calculations presented in the companion paper, a detailed kinetic mechanism was developed in order to reproduce the present data and analyze the reaction pathways. [ABSTRACT FROM AUTHOR]

The oxidation of di-n-propyl-ether (DPE) was performed in a jet-stirred reactor at 1 and 10 atm, at residence times of 1 and 0.7 s, respectively, and initial fuel concentrations of 5000 and 1000 ppm at 1 and 10 atm, respectively. Atmospheric pressure experiments were used for characterization of cool flame products. The 10 atm experiment provided KHPs profile vs. temperature and mole fraction profiles of stable species which were obtained through sonic probe sampling, gas chromatography, Fourier transform infrared spectrometry analyses. High resolution mass spectrometry analyses (HRMS) with syringe direct injection or ultra-high-pressure liquid chromatography coupling was used to characterize hydroperoxides (C 3 H 8 O 2 , C 6 H 14 O 3), diols (C 6 H 14 O 3), ketohydroperoxides (C 6 H 12 O 4), carboxylic acids, and highly oxygenated molecules (C 6 H 12 O 6 , C 6 H 12 O 8) resulting from up to four O 2 additions on fuel's radicals. Heated electrospray and atmospheric pressure chemical ionizations (HESI and APCI) were used in positive and negative mode. Whereas the CH 2 groups neighboring the ether function are the most favorable sites for H-atom abstraction reactions, speciation indicated that other sites can react by metathesis forming a large pool of intermediates. Our kinetic reaction mechanism represents the experimental data for most of the stable species but need to be expended for simulating the formation of newly detected species. [ABSTRACT FROM AUTHOR]

Pyrolysis of diethyl (C 4), di-n-propyl (C 6), di-isopropyl (C 6) and di-n-butyl (C 8) ethers were studied in a jet-stirred reactor between 720 and 1140 K, at 10 atm with an initial ether mole fraction of 0.1%. Major common pyrolysis products were observed to be CO, CH 4 , H 2 , and C 2 H 4. All ethers produced the n/2 alcohol and olefin as products of molecular reaction to a small extent. Under pyrolysis conditions at 10 atm, hydrogen abstraction reactions by H atoms and CH 3 radicals were found to be important. Acetylene and benzene were formed for all ethers when T > 1000 K. A kinetic mechanism is used to represent these results. This study shows that there is need of systematic studies in determining site specific rate constants of important fuel related reactions of ethers. [ABSTRACT FROM AUTHOR]

Theoretical investigations on the kinetics of pentan-2-ol radical decomposition and isomerization reactions have been carried out in this work, together with the thermochemistry data calculations for important species involved in the reaction process. The B2PLYPD3/6-311++G(d,p) level of theory was used to optimize the geometries of all of the reactants, transition states, products and also the hindered rotor treatment for lower frequency modes. Single-point energies of all species are determined at the ROCCSD(T) level using the cc-PVQZ and cc-pVTZ which were extrapolated to the complete basis set limit (CBS). RRKM/Master Equation has been solved to calculate the pressure- and temperature-dependent rate coefficients for all channels in the pressure range of 0.01–100 atm over 300–2000 K. Pressure and temperature dependent branching fractions of key species produced from different pentan-2-ol radicals shows that 1- and 2-pentene are important bimolecular products. The kinetics and thermochemistry data for the title reactions has been used in the part II of this work for model development for pentan-2-ol oxidation. [ABSTRACT FROM AUTHOR]

Byline: Zeynep Serinyel, Luis Le Moyne, Philippe Guibert I.C. engines must fulfill environmental requirements, deliver high power and torque, at low fuel economy and cost. Diesel engines produce high levels of NOx and particulate matter, spark ignition engines have lower efficiency. Homogeneous charge compression ignition appears as a new combustion technique that could combine in itself the advantages of both engines, significant soot and NOx reduction and low consumption. Various names have been attributed to this particular mode of combustion such as ATAC, UNIBUS, CAI, CIHC, PCCI, etc. This paper aims to give an overview of this combustion mode, and its chemical and thermodynamic aspects.