Investigation of particulate emission characteristics of a diesel engine fueled with higher alcohols/biodiesel blends

A systematic study was conducted to make a comparative evaluation of the effects of blending n-butanol and n-pentanol with biodiesel at 10% and 20% by volume on engine performance and on the physico-chemical characteristics of particulate emissions from a single cylinder, direct injection diesel engine. The engine was operated at a constant engine speed and at three engine loads. Compared to biodiesel, butanol-biodiesel blends lead to a maximum of 1.6% increase in the brake thermal efficiency (BTE) and an increase in the brake specific fuel consumption (BSFC) by 1.9-3.9% at low and medium engine loads. Pentanol-biodiesel blends result in an improvement in the BTE and a maximum of 2% increase in the BSFC. Compared to biodiesel, both the blended fuels can reduce the particulate mass and elemental carbon (EC) emissions, with butanol being more effective than pentanol. The blended fuels also show a lower emission of total particle-phase polycyclic aromatic hydrocarbons (PAHs) and also a lower carcinogenic potential. However, the proportion of particulate-bound organic carbon (OC) and water-soluble organic carbon (WSOC) are increased for the both blended fuels, especially for 20% butanol in blends. The emissions of volatile and solid particles are reduced significantly in terms of their counts for both kinds of blended fuels at medium and high engine loads, whereas the total particle counts for both 10% and 20% butanol in blended fuels are increased at low engine load due to a significant increase in particles with diameter less than 15 nm.