The effect of cottonseed oil methyl ester on the performance and exhaust emissions of a diesel engine

The scarce and rapidly depleting conventional petroleum resources have promoted research for alternative fuels for internal combustion engines. In view of this, vegetable oil is a promising alternative fuel for diesel engines as it has several advantages. The high viscosity causes some problems in atomisation of injector systems and combustion in cylinders of diesel engines. In present research, to decrease viscosity of raw cottonseed oil, cottonseed methyl ester is obtained by transesterification process. The fuel properties of cottonseed methyl ester such as kinematic viscosity, calorific value, flash point, fire point, carbon residue and density were determined. Experiments were carried out using a single cylinder, four stroke, constant speed, water cooled, direct injection diesel engine. The acquired data were analysed for various parameters such as brake thermal efficiency, specific fuel consumption and exhaust gas temperature. Results indicated that Diesel with 25% esterified cottonseed oil fuel had closest performance to mineral diesel. The brake thermal efficiency for biodiesel and its blends is found to be slightly higher than that of diesel fuel at tested load conditions. For cottonseed biodiesel and its blended fuels, the exhaust gas temperature increased with increase in load. The engine experimental results showed that exhaust emissions including CO, CO2 and HC emissions were reduced for all biodiesel mixtures. However, there was a slight increase in emission of oxides of nitrogen (NOx) using biodiesel blends.