The effects of biodiesel from waste frying oils on engine performance and exhaust emissions

In this thesis, biodiesel (B100) produced by transesterification from waste frying oil was tested in a single cylinder, direct injection diesel engine and its effects on engine performance and exhaust emissions were investigated. The values obtained from B100 and diesel fuels were compared with each other. The experiments were carried out at full load at 1800-3000 rpm with 400 rpm intervals. According to the test results, engine torque decreased by 6.64% compared to diesel fuel by using B100 fuel. However, with the use of B100, specific fuel consumption increased by 15.7% compared to diesel fuel. The low thermal value and high viscosity of biodiesel compared to diesel fuel are factors that reduce engine torque. Furthermore, CO and HC emissions were reduced by 25.4% and 5.5%, respectively, compared to diesel fuel with the use of B100. The high amount of oxygen contained in the biodiesel improves combustion where incomplete combustion and rich mixture occur. However, NOX emissions increased by 9.5% compared to diesel fuel with the use of biodiesel. Oxygen in the biodiesel increases the number of combustion zones and so the temperature. High temperature, prolonged reaction and high oxygen content trigger NOX formation.