Performance and emission of diesel engine fuelled by waste cooking oil methyl ester derived from palm olein using hydrodynamic cavitation

The depleting of fossil fuel reserves and increasing environmental concerns have continued to stimulate research into biodiesel as a greener fuel alternative produced from renewable resources. In this study, the performance and emission characteristics of biodiesel blends of 10, 30 and 50 % from waste cooking oil based on hydrodynamic cavitation were compared to diesel fuel, and found to be acceptable according to the EN 14214 and ASTM D 6751 standards. The tests have been performed using an in-line vertical six-cylinder diesel engine at different engine speeds, ranging from 1000 to 2000 rpm under full throttle load. During engine performance tests, biodiesel blends showed higher brake specific fuel consumption (2.1-9.0 %) and exhaust gas temperature (1.0-6.8 %), while lower brake power (1.6-6.7 %), torque (0.6-5.2 %) and brake thermal efficiency (1.9-8.4 %) than diesel fuel. Engine emissions showed higher carbon dioxide (8.7-38.5 %) and nitrogen oxide (4.7-19.0 %) releases, but surprisingly decreased amount of carbon monoxide (3.3-26.3 %) for biodiesel blends compared to diesel fuel. Although higher carbon dioxide amounts were emitted, the use of biodiesel greatly reduced the life cycle circulation of carbon dioxide. Waste cooking methyl ester produced by using hydrodynamic cavitation seems to be relatively easy to scale up to higher production values, is energy efficient, time saving and eco-friendly, which results in biodiesel being a viable fuel for industrial production. The waste cooking oil-based biodiesel can also be used without any engine modifications.