Development and Parametric Evaluation of a Tabulated Chemistry Tool for the Simulation of n-Heptane Low-Temperature Oxidation and Autoignition Phenomena

Abstract

Accurate modelling of preignition chemical phenomena requires a detailed description of the respective low-temperature oxidative reactions. Motivated by the need to simulate a diesel oil spray evaporation device operating in the “stabilized” cool flame regime, a “tabulated chemistry” tool is formulated and evaluated. The tool is constructed by performing a large number of kinetic simulations, using the perfectly stirred reactor assumption. n-Heptane is used as a surrogate fuel for diesel oil and a detailed n-heptane mechanism is utilized. Three independent parameters (temperature, fuel concentration, and residence time) are used, spanning both the low-temperature oxidation and the autoignition regimes. Simulation results for heat release rates, fuel consumption and stable or intermediate species production are used to assess the impact of the independent parameters on the system’s thermochemical behaviour. Results provide the physical and chemical insight needed to evaluate the performance of the tool when incorporated in a CFD code. Multidimensional thermochemical behaviour “maps” are created, demonstrating that cool flame activity is favoured under fuel-rich conditions and that cool flame temperature boundaries are extended with increasing fuel concentration or residence time.