Experimental Investigations on Cotton Seed Biodiesel Fuelled DI Diesel Engine with Low Heat Rejection Combustion Chamber

Biodiesels derived from vegetable oils present a very promising alternative for diesel fuel; since they 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 drawbacks associated with biodiesel of high viscosity and low volatility which cause combustion problems in CI engines, call for engine with hot combustion chamber with its significant characteristics of higher operating temperature, maximum heat release, and ability to handle low calorific value fuel. Investigations were carried out to evaluate the performance of a engine with low heat rejection combustion chamber consisting of an air gap insulated piston, an air gap insulated liner and ceramic coated cylinder head with different operating conditions of cotton seed biodiesel with varied injection timing and injector opening pressure. Performance parameters and exhaust emissions were determined at full load operation of the engine. Combustion characteristics of the engine were measured at full load operation with water cooled Piezo-electric pressure transducer, TDC (top dead centre) encoder and pressure–crank angle software package. Finite element method was applied to determine isotherms in order to evaluate the performance of lubricating oil with change of configuration of combustion chamber and results were correlated with experimental investigations. The optimum injection timing with conventional engine (CE) was 31o bTDC, while it was 28o bTDC for engine with LHR combustion chamber with biodiesel. Comparative studies were made for engine with LHR combustion chamber and CE at manufacturer’s recommended injection timing (27o bTDC) and optimum injection timing with biodiesel operation. Engine with LHR combustion chamber with biodiesel showed improved performance over CE at 27o bTDC and at optimum injection timing. Temperature of lubricating oil predicted by FEM was within the limits.