Effect of Combustion Chamber Shapes on the Performance of Mahua and Neem Biodiesel Operated Diesel Engines

Abstract

Shape of combustion chamber plays a major role in controlling combustion process and emission characteristics occurring inside internal combustion engines in general and diesel engines in particular. To optimize a combustion chamber for diesel engine applications, suitable design modifications are required that meet both emission norms as well as acceptable engine performance. In this context, experimental investigations were carried out on a single cylinder four stroke direct injection diesel engine operated in single fuel mode using Mahua oil methyl ester (MhOME) and neem oil methyl ester (NOME). Different combustion chamber shapes were designed and fabricated keeping the compression ratio same for the existing diesel engine. The existing engine was provided with hemispherical combustion chamber (HCC) shape. In order to study the effect of other combustion chamber shapes on the performance of diesel engine, cylindrical (CCC), trapezoidal (TrCC), and toroidal combustion chamber (TCC) shapes were designed and developed. Various engine parameters such as power, torque, fuel consumption, and exhaust temperature, combustion parameters such as heat release rate, ignition delay, combustion duration, and exhaust emissions such as smoke opacity, hydrocarbon, CO, and NOx, were measured. Results revealed that the TCC shape resulted in overall improved performance with reduced emission levels compared to other shapes tested. Total hydrocarbon emission (THC) and carbon monoxide (CO) were also decreased significantly compared to other combustion chambers.