Characterization of exhaust particulates from diesel engine

This study was set out to characterize particulate emissions from a mid-sized diesel engine in terms of metals, benzene soluble fraction, elemental and organic carbon. For this study, the exhaust particulates from Mahindra direct injection transportation diesel engine (40 hp) were collected at four different engine operating conditions, namely idle, 40%, 70% and full load for the above parameters. It was found that as the load increased from idling to full load, the metal content in particulates gradually decreased. The metal content in exhaust particulates was correlated with that of metal content in diesel. Benzene soluble fraction, which is a marker for carcinogenicity, also showed decrease in its level with increasing load. It was found that at idling, 67% of mass was soluble in benzene while at full load it was only about 24%. Elemental carbon content increased with increase in load showing a maximum of 48% at 70% load and a minimum of 25% at idling. The trend of organic carbon was quite opposite; it showed 35% organic carbon at idling, which decreased gradually with increase in load. This research has suggested that composition of diesel exhaust particles varies significantly with varying engine load conditions.