A study on the effect of temperature on soot formation in a jet stirred combustor

Abstract

In an attempt to understand soot formation mechanisms and predict soot yields in practical combustion systems, experiments were conducted in a toluene/air turbulent premixed flame in a jet stirred combustor (JSC). Soot mass concentrations were measured via a laser extinction technique and soot particle diameter and number density were measured via a laser extinction technique and soot particle diameter and number density were measured via a combination laser extinction/scattering technique. A global soot model was utilized to analyze rates of particle nucleation, coagulation, and specific surface growth. In order to study the effect of flame temperature on soot formation, one uncooled and three water cooled JSCs were prepared. Soot mass concentration measurements showed strong dependency of the soot production on stoichiometry, residence time, and flame temperature. It was found that as temperature became lower the incipient soot limit became lower, which indicated a greater sooting tendency at a lower flame temperature. The soot mass concentration was found to maximize at a flame temperature of approximately 1200∼1400°C. It was also found that the soot particle diameter increased with temperature. The measurements and the results of a global soot model calculation showed that particle nucleation decreased and the specific surface growth rate increased with an increase in temperature above the maximum sooting temperature.