An experimental and modeling study of the combustion of toluene

The present work falls under two broad categories, (1) The experimental and modeling study of the combustion of toluene. The oxidation and pyrolysis of toluene---the primary aromatic gasoline surrogate molecule has been studied behind reflected shock waves using the high pressure single pulse shock tube. Experiments for the oxidation of toluene were performed at pressures of 25, 50 and 550 bars over the temperature range 1200--1500 K whereas the pyrolysis experiments were performed at 22 and 45 bars over a wider temperature range from 1200--1900 K. A variety of stable species sampled from the shock tube were analyzed using standard chromatographic techniques. A detailed chemical kinetic model was developed to predict the species profiles from the experiments. The model was extended to predict data obtained from other laboratories over a wide range of experimental conditions, specifically flow reactor species profiles and ignition delay measurements in shock tubes with a good degree of success thereby making the model more comprehensive. (2) Development of a new technique for estimating the heats of formation of PAHs. The heats of formation (DeltaHf0298K) in the gas phase were estimated for a set of common aromatic and PAH molecules using a new reaction scheme referred to as the Ring Conserved (RC) Isodesmic Reaction Scheme. The new scheme involves an indirect parametrization of resonance to define a unique reaction for the molecule of interest. The new scheme, which is cost effective, utilizes energetics calculated using a low level DFT calculation (B3LYP/6-31G*) to obtain accurate estimates of experimental DeltaHf0 298K for a test set of 30 aromatics and PAHs with well defined experimental measurements with mean absolute deviations less than 1.5 kcal/mol. The RC isodesmic scheme has also been used to obtain DeltaHf0 298K for aromatics, PAHs and radicals for which there are no or uncertain experimental measures.