Effect of Engine Operating Conditions on Nanostructure and Oxidation Reactivity of Soot Particles from Diesel Engine

Abstract

Effect of engine operating conditions on nanostructure and oxidation reactivity of soot particles from diesel engine was investigated experimentally. The soot nanostructure, i.e., the graphitic crystallite size and the amorphous carbon content in the soot particles, was characterized by Raman spectroscopy. Oxidation reactivity of soot was evaluated by temperature-programmed oxidation (TPO). The soot Raman spectra showed that the size of graphitic crystallite in the soot increases with increasing exhaust temperature resulting from the increase of the engine load. In addition, the graphitic crystallite size of soot obtained during lower engine speed was slightly larger than that of higher engine speed of same exhaust temperature. The results of TPO indicated that the oxidation reactivity of soot decreases with the increase of graphitic crystallite size.