Diesel Exhaust Particulate Characterization for Poly Aromatic Hydrocarbons and Benzene Soluble Fraction 2005-26-348

This study was set out to characterize particulate emissions from diesel engines in terms of poly aromatic hydrocarbon emissions and Benzene Soluble Organic Fraction. The characteristics of DPM vary with engine operating conditions, quality of fuel and lubricants being used. Hence the diesel exhaust for the purpose of toxicity characterization needs to be studied for Organic Matter in terms of Poly Aromatic Hydrocarbon (PAH) and Benzene Soluble Fraction (BSF). Therefore, the objectives of the present research are to characterize the diesel exhaust particulate matter for the above parameters under varying engine operating conditions/loads.

Six PAHs, namely Chrysene, Benzo (k) Flouranthene, Benzo (a) Pyrene, Dibenzo (a, h) Anthracene, Benzo (g,h,i) Perylene and Indenopyrene were analyzed on High Pressure Liquid Chromatography (HPLC). PAH concentrations in the particulates of Mahindra DI engine were affected by engine loads. BSF, which is a marker for carcinogenicity, showed a decrease in levels with increasing load. It was found that at idling, 67% of organic fraction was soluble in benzene with a minimum of 25 % at full load. This can be explained by the fact that at idle condition the diesel and lubricating oil undergoes partial combustion (pyrolysis) due to low temperature conditions prevailing in the combustion chamber. This leads to higher unburnt hydrocarbon species emission, which are detected as BSF. This research has suggested that composition of diesel exhaust particles varies significantly with varying engine load conditions. Therefore, there is a need to account for varying engine loads and quality of fuel while estimating (i) emission source profile, (ii) emission inventory, (iii) health implications and (iv) pollution control planning.