Effect of Injection Timing Retard on Emissions and Performance of a Pongamia Oil Methyl Ester Fuelled CI Engine

Injection timing variations have a strong effect on NOx emissions for direct injection diesel engines. Retarded injection is commonly used to control NOx emissions. Biodiesel is a non-toxic, biodegradable and renewable fuel with the potential to reduce engine exhaust emissions. The methyl ester of pongamia oil, known as biodiesel, is receiving increasing attention as an alternative fuel for diesel engines. In the present investigation neat pongamia oil methyl ester (PME) as well as the blends of varying proportions of pongamia oil methyl ester (PME) and diesel were used to run a CI engine with standard injection timing and retarded injection timing. Significant improvements in engine performance and emission characteristics were observed for PME fuel. The addition of PME to diesel fuel has significantly reduced HC, CO, and smoke emissions but it increases the NO_X emission slightly with standard injection timing. The NO_X emission was decreased with retarded injection timing with negligible effect on fuel consumption rate. Similar trend in brake thermal efficiency and exhaust gas temperature was observed with retarded injection timing while maximum cylinder gas pressure and ignition delay was decreased.