Experimental investigation of the effect of compression ratio and injection pressure in a direct injection diesel engine running on Karanj methyl ester

Being a fuel of a different origin, the standard design parameters of a diesel engine are not optimum for Karanj methyl ester (KME). This study aims at finding the effect of the engine design parameters, viz. compression ratio (CR) and fuel injection pressure (IP) jointly on the performance and emissions. Brake-specific fuel consumption (BSFC) and brake thermal efficiency (BTE) were considered for performance evaluation, and emission analysis was done for un-burnt hydrocarbon, carbon monoxide (CO), carbon dioxide (CO2), oxides of nitrogen (NO x ), exhaust gas temperature and smoke opacity with KME as the fuel. Comparison of performance and emission was done for different values of CR along with IP to find the optimum combination for operating engine with KME. It is found that the combined increase in CR and IP increases the BTE and reduces BSFC while having lower emissions. For small-sized direct injection constant speed engines used for agricultural applications (3.5 kW), the optimum combination was found to be CR of 18 with IP of 250 bar.