Combustion and Flame, Vol.211, 392-405, 2020
Ignition delay time and species measurement in a rapid compression machine: A case study on high-pressure oxidation of propane
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 747K 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. (C) 2019 The Combustion Institute. Published by Elsevier Inc. All rights reserved.