Detailed Kinetic Modelling of Toluene Combustion

Abstract

A detailed chemical kinetic mechanism for the combustion of toluene has been assembled and evaluated for a wide range of combustion regimes. The latter include counterflow diffusion flames, plug flow reactors, shock tubes and premixed flames. The reaction mechanism features 743 elementary reactions and 141 species and represents an attempt to develop a chemical kinetic mechanism applicable to intermediate and high temperature oxidation. Toluene thermal decomposition and radical attack reactions leading to oxygenated species are given particular attention. The benzyl radical sub-mechanism is expanded to include izomerization and thermal decomposition reactions, which are important at flame temperatures, and a molecular oxygen attack path to form the benzylperoxy radical, which is found to be relevant at lower temperatures, The final toluene kinetic model results in excellent fuel consumption profiles in both flames and plug flow reactors and sensible predictions of the temporal evolution of the hydrogen radical and pyrolysis products in shock tube experiments. The structures of tol-uene/n-heptane, toluene/n-heptane/methanol and toluene/methanol diffusion flames are predicted with reasonable quantitative agreement for major and minor species profiles. Furthermore, the evolution of major and intermediate species in plug flow reactors is well modelled and excellent laminar burning velocity predictions have also been achieved.