Combustion kinetics of soot formation from toluene

Abstract

The combustion kinetics of soot formation for toluene and other selected fuels was studied behind reflected shock waves over the temperature range 1400 to 2500 K and the pressure range 2.5 to 10 atm using a laser beam attenuation technique. The limitations of the optical method employed to measure soot concentrations were investigated, and the index of refraction of soot particles was identified as the major factor which limits the accuracy of these experiments. Detailed soot yield studies show that the aromaticity of the hydrocarbons determines their sooting ability and that condensation, polymerization, and dehydrogenation are the most important soot formation steps for aromatic fuels. Thermochemical equilibrium calculations indicate that C 96 H 24 appears to be an important soot precursor. Correlation equations for soot formation delay times, apparent soot formation rates, and quasi-global rate models were obtained. The data presented herein may be used to estimate the effects on sooting which are caused by using highly aromatic, synthetic fuels.