Using waste animal fat based biodiesels-bioethanol-diesel fuel blends in a DI diesel engine

In this study, animal fat based biodiesels produced in the pilot plant were blended with certain amounts of diesel fuel and bioethanol. Neat biodiesels, diesel fuel and the blends were tested in a direct injection diesel engine and engine performance, combustion and exhaust emission characteristics were investigated. Engine tests were conducted at constant engine speed (1400 rpm) and four different engine loads (150 Nm, 300 Nm, 450 Nm and 600 Nm). The engine tests showed that the brake specific fuel consumptions (BSFC) of biodiesels were about 16% higher while those of the blends containing 20% bioethanol were about 15.7% higher than those of diesel fuel on average. The maximum cylinder gas pressures of biodiesels were about 1.2% higher than those of diesel fuel on average. The start of combustion of biodiesels occurred at earlier crank angles compared to diesel fuel, while the start of combustion occurred at later crank angles with increasing bioethanol amount in the fuel blends. According to brake specific emission results, biodiesels emitted lower carbon monoxide (CO) emissions but they emit higher carbon dioxide (CO2) and oxides of nitrogen (NOx) emissions as compared to diesel fuel. THC emissions increased and CO2 emissions reduced slightly for the blends containing bioethanol compared with B20 (20% biodiesel, 80% diesel fuel) on average.