REDUCTION OF EXHAUST EMISSIONS OF SEMI ADIABATIC DIESEL ENGINE WITH ALTERNATIVE FUELS

Drawbacks associated with crude vegetable oils (high viscosity and low volatility) and alcohol (low energy content and cetane number) for use in compression ignition engine call for biodiesels. These biodiesels have numerous advantages compared to fossil fuels as they are renewable, biodegradable, provide energy security and foreign exchange savings besides addressing environmental concerns and socio-economic issues. However, these alternative fuels (vegetable oils and its biodiesels) are highly to moderate viscous and require hot combustion chamber, provided by semi adiabatic diesel engine. Investigations were carried out to determine exhaust emissions of a high grade semi adiabatic diesel engine consisted of air gap insulated piston, air gap insulated liner and ceramic coated cylinder head with different operating conditions [normal temperature and pre-heated temperature] of crude rice bran oil and its biodiesel with varied injector opening pressure. Exhaust emissions were determined at various values of brake mean effective pressure of the engine fuelled with crude rice bran oil and its biodiesel. Comparative studies on exhaust emissions were made with diesel working on similar conditions. Particulate emissions decreased, while NOx levels increased with LHR engine with biodiesel operation. Exhaust emissions improved with increase of injector opening pressure and preheating of biodiesel.