A chemical kinetic perspective on the low-temperature oxidation of propane/propene mixtures through experiments and kinetic analyses

Abstract Our understanding of fuel oxidation has improved with rigorous experimental and theoretical investigations being performed in recent years. As investigation methods evolve, our understanding of fundamental fuel chemistry advances. This process allows us to revisit and improve our existing chemical kinetic models. Propane and propene have been studied in various facilities at different conditions; however, the interaction of these two species has not been explored well. These two species play a crucial role in the oxidation of larger hydrocarbons and constitute a significant fraction of liquefied petroleum gas. The current study involves an experimental investigation of ignition delay time measurements for neat propene and propane/propene (50%/50%) mixtures in a rapid compression machine for a range of pressures (20–80 bar). These auto-ignition experiments are complemented by the measurement of stable intermediate species mole fraction profiles at 750 K for the non-diluted stoichiometric condition at 40 bar and 50 bar. The experimental output from this study has contributed to the development of NUIGMech1.0 at high-pressure conditions for mixtures that are relevant to engine applications. NUIGMech1.0 is utilized for the kinetic analysis, and its performance is also compared with two other relevant mechanisms. The kinetic analysis is used to understand the fundamental chemistry controlling fuel oxidation and provide updates of the chemical kinetic mechanism. Additionally, the critical reaction pathways and sensitive reactions that lead to the intermediate species that control reactivity are explained in detail. It is found that cross-reactions from both the propane and propene sub-mechanisms play a crucial role in controlling the reactivity of the mixtures. NUIGMech1.0 captures the reactivity and speciation data for the neat components and shows good predictions of the mixtures at the conditions studied.