Abstract: Petroleum fuels are widely known and utilizing fuels, due to petroleum fuel depletion and environmental degradation. Renewable, carbon neutral, bio-fuels are necessary for environmental and economic sustainability. Biodiesel derived from oil seeds is a potential renewable alternative fuel to petroleum diesel. Chemically, biodiesel is a mono alkyl ester of long chain fatty acids derived from renewable feed stock like edible/non edible vegetable oils and animal fats. It is produced by transesterification process in which, oil is reacted with a monohydric alcohol in presence of a catalyst. Palm methyl ester was chosen for present experimental study. The effect of Palm methyl ester on the performance, emission and combustion characteristics of a single cylinder 4-stroke diesel engine at varying injection pressure was studied through experimental work. It was observed that the fuel penetration distance become longer and the mixture formation of the fuel and air was improved when the combustion duration became shorter as the injection pressure became higher. When fuel injection pressure is low, fuel particle diameters will enlarge and ignition delay period during the combustion will increase. This situation leads to inefficient combustion in the engine and causes the increase in emissions like NOx and CO. When the injection pressure is increased fuel particles diameters will become small, the mixing of fuel and air becomes better during ignition delay period which causes low CO emission. Maximum brake thermal efficiency of 30.33% was obtained at an injection pressure of 260 bars. Palm methyl ester fuel exhibited lower cylinder gas pressure and higher heat release rate at an injection pressure 260 bar. Palm methyl ester showed reduction in carbon monoxide (CO), carbon dioxide (CO2) and nitric oxide (NO) but slight increase in the levels of unburnt hydrocarbon (HC) with higher injection pressure.
Keywords: Biodiesel, Palm Methyl Ester, single cylinder 4-stroke diesel engine, emissions, performance.