Modeling of autoignition and NO sensitization for the oxidation of IC engine surrogate fuels

TL;DR

This paper introduces a comprehensive kinetic model that simulates autoignition and NOx-sensitized oxidation of surrogate fuels in engines, validated across various experimental setups and temperature regimes.

Contribution

A new unified kinetic model for autoignition and post-oxidation of surrogate fuels, including NOx interactions, valid over a wide temperature range.

Findings

Model accurately predicts autoignition timings across experiments.

NOx significantly influences low-temperature hydrocarbon oxidation.

Flow and sensitivity analyses elucidate NOx impact mechanisms.

Abstract

This paper presents an approch for modeling with one single kinetic mechanism the chemistry of the autoignition and combustion processes inside an internal combustion engine, as well as the chemical kinetics governing the post-oxidation of unburned hydrocarbons in engine exhaust gases. Therefore a new kinetic model was developed, valid over a wide range of temperatures including the negative temperature coefficient regime. The model simulates the autoignition and the oxidation of engine surrogate fuels composed of n-heptane, iso-octane and toluene, which are sensitized by the presence of nitric oxides. The new model was obtained from previously published mechanisms for the oxidation of alkanes and toluene where the coupling reactions describing interactions between hydrocarbons and NOx were added. The mechanism was validated against a wide range of experimental data obtained in jet-stirred reactors, rapid compression machines, shock tubes and homogenous charge compression ignition engines. Flow rate and sensitivity analysis were performed in order to explain the low temperature chemical kinetics, especially the impact of NOx on hydrocarbon oxidation.