EFFECT OF USED COOKING OIL METHYL ESTER ON COMPRESSION IGNITION ENGINE

Biodiesel is a fuel derived from vegetable oils or animal fats which are basically long chain triglyceride esters with free fatty acids. The long chain triglyceride ester is converted into mono ester by the process called transesterification. In this process the vegetable oils are reacted with methanol or ethanol in the presence of acid or base catalyst producing fatty acids methyl or ethyl ester.In this study used cooking oil was transesterified using 1% sodium hydroxide and 20 % methanol at the temperature range of 65-69°C. The reaction time was two hours and conversion efficiency was 92.5%. The physical and chemical properties of the biodiesel were determined in accordance with ASTM 6751.The biodiesel was used as fuel in a four stroke, three cylinder, naturally aspirated engine, in pure as well as in the blended form. Engine performance and emissions were studied. The results showed that specific fuel consumption was increased by increasing the ratio of biodiesel in the blends. However there was notable decrease in CO, CO2, THC and SOx emissions and a minor increase in NOx emission.