PAH emissions and energy efficiency of palm-biodiesel blends fueled on diesel generator

This study investigated the emissions of polycyclic aromatic hydrocarbons (PAHs), carcinogenic potencies (BaPeq) and particulate matter (PM), fuel consumption and energy efficiency from the generator under steady state for seven test fuels: P0 (Premium Diesel Fuel), P10 (10% palm biodiesel+90% P0), P20, P30, P50, P75 and P100. Experimental results indicated that PAH emission decreased with increasing palm-biodiesel blends due to small PAH content in biodiesel. The mean reduction fraction of total PAHs emission factor (P0=1110 μg L−1) from the exhaust of diesel generator were 13.2%, 28.0%, 40.6%, 54.4%, 61.89% and 98.8% for P10, P20, P30, P50, P75 and P100, respectively, compared with P0. The mean reduction fraction of total BaPeq (P0=1.65 μg L−1) from the exhaust of diesel generator were 15.2%, 29.1%, 43.3%, 56.4%, 58.2% and 97.6% for P10, P20, P30, P50, P75 and P100, respectively, compared with P0. PM emission decreased as the palm-biodiesel blends increased from 0% to 10%, and increased as the palm-biodiesel blends increased from 10% to 100% because the soluble organic fraction of PM emission was high in blends with high palm-biodiesel content. The brake specific fuel consumption rose with rising palm-biodiesel blends due to the low gross heat value of palm-biodiesel. The increasing fraction of BSFC of palm-biodiesel was lower than those of soy-, soapstock-, brassica-carinate and rapeseed-biodiesel. Palm-biodiesel seems to be the most feasible biodiesel. The best energy efficiency occurred between P10 and P20, close to P15. The curve dropped as the palm-biodiesel content rose above P20. Above results revealed that palm-biodiesel was an oxygenated fuel appropriate for use in diesel engines to promote combustion efficiency and decrease PAH emission. However, adding an excess of palm-biodiesel to P0 leaded to incomplete combustion in the diesel-engine generator and inhibited the release of energy in the fuel.