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Short-carbon-chain ketones are known for their high octane numbers, their knock resistance, and their low soot emission. However, studies on the combustion behavior of ketones, particularly in the low temperature regime, are sparse, and small ketones as acetone and butanone show limited low temperature chemistry (LTC). Therefore, saturated linear five-carbon ketones are good candidates to better understand the LTC of ketones and the effect of the functional carbonyl group. In this study, the ignition delay times of stoichiometric non-diluted 2- and 3-pentanone-oxygen-inert gas mixtures were measured in a rapid compression machine at pressures between 20 and 40 bar and temperatures ranging between 650 and 950 K. Furthermore, the mole fraction profiles of fuel, oxygen, intermediate species, and products were measured in a laminar flow reactor coupled with molecular-beam mass spectrometry at 0.97 bar, an equivalence ratio of 0.8 and temperatures ranging from 800 to 1050 K, to achieve a better understanding of the oxidation process of linear pentanones. A consistent detailed kinetic model was developed and validated against the newly measured experimental data for 2-pentanone and 3-pentanone to provide insight into the oxidation mechanism of pentanones. The model shows also good agreement with available data from the literature, including ignition delay times measured in a shock tube, speciation in a flat flame burner and laminar burning velocities. [ABSTRACT FROM AUTHOR]

To understand and develop a robust kinetic model for describing the oxidation of a fuel, knowledge of different physicochemical parameters is essential. It can be global parameters like ignition delay times (IDTs) and laminar burning velocities or intrinsic local parameter like species mole fraction profiles. Different facilities have been utilized to provide such measured values from a wide range of conditions that aid in the validation of a detailed chemical kinetic mechanism. In this study, IDT and stable intermediate species mole fractions were obtained for a non-diluted stoichiometric mixture of propane/oxygen/inert gas at compressed pressures of 30 and 50 bar in a rapid compression machine. The species mole fractions during the ignition delay period were obtained at 747 K for 50 bar and 765 K for the 30 bar condition. The species measurement for non-diluted mixtures at such high pressures is vital as there is a change in the sensitivities of the important reactions at these conditions. The non-diluted mixture under this range of pressures represent the application relevant conditions, and the speciation measurement is, for the first time investigated at such conditions in an RCM. This aspect directly highlights the novelty of this study. The work elaborates, in detail, the methodology used for the measurement and simulation of the species mole fraction at the measured conditions with emphasis on the relevant uncertainties. The discussion also includes the significance of sampling from the reaction core and the outcome of the results when sampling from the boundary layer. The IDT measurements are utilized to find a suitable mechanism from the literature that well represents the reactivity both qualitatively and quantitatively in the measured regime. The selected mechanism is used for the simulation and comparison with the measured species mole fractions profiles. The sensitivity and rate of production analysis are performed using the selected mechanism to comprehend the important pathways leading to the formation of the key stable species observed in this experimental work. [ABSTRACT FROM AUTHOR]

The pyrolysis and oxidation of acetone were studied using three complementary experimental setups. Jet-stirred reactor experiments were performed at four equivalence ratios (ϕ = 0.5, 1, 2, and ∞), at pressure of 1.067 bar (800 Torr) and over the temperature range of 700–1200 K for pyrolysis and 600–1150 K for oxidation. The decomposition of acetone starts around 800 K with a conversion rate of 50% obtained around 1000 K in both pyrolysis and oxidation studies. The main stable products detected in both conditions are small hydrocarbons (methane, ethane, and ethylene), with also acetaldehyde, CO and CO 2 for oxidation. Oscillation behavior was detected beyond 1000 K under oxidation conditions and the products were followed with on-line mass spectrometry. Ignition delay times were measured using a rapid compression machine at pressures of 20 and 40 bar under non-diluted stoichiometric conditions over the temperature range 850–1100 K. The ignition delay times measured in the present study, combined with shock tube data of literature, exhibit a slight inflexion to the Arrhenius behavior, but no negative temperature coefficient. Laminar burning velocities were measured using a flat flame burner at atmospheric pressure for three fresh gas temperatures: ambient temperature, 358 and 398 K. A detailed kinetic model of the combustion of acetone including 852 species and 3265 reactions was developed. This new kinetic mechanism predicts relatively well the experimental measurements of ignition delay times, the mole fraction of the products in the jet-stirred reactor including oscillations and laminar burning velocities. Related flow rate and sensitivity analysis are also presented providing new insights into the acetone reaction network. [ABSTRACT FROM AUTHOR]