Overview of EGR, Injection Timing and Pressure on Emissions and Performance of CI Engine with Pongamia Methyl Ester

Exhaust Gas Recirculation (EGR) is one of the most effective means of reducing NOx emissions from compression ignition engines. Retarded injection is also used to control NOx emissions. Higher fuel injection pressure may improve the combustion. EGR can be combined advantageously with other emission reducing measure such as retarded injection timing and performance improvement measures such as higher fuel injection pressure to have a good effect. In the present investigation neat pongamia oil methyl ester (PME) as well as the blends of varying proportions of PME and diesel were used to run a CI engine with standard conditions and with combination of 20 % EGR, 4° retarded injection timing and 30 MPa fuel injection pressure. 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. The pongamia oil methyl ester was obtained through transesterification process. Various properties of the biodiesel thus developed were evaluated and compared in relation to that of conventional diesel oil. The addition of pongamia oil methyl ester (PME) to diesel fuel has significantly reduced HC, CO and smoke emissions but it increases the NO_X emissions slightly with standard conditions. The NO_X emission was drastically decreased with modified conditions. Further the smoke and unburned hydrocarbon emissions were decreased with modified conditions as compared to standard conditions. The brake thermal efficiency was improved with modified conditions at various loads. Exhaust gas temperatures were similar. The maximum cylinder pressure and heat release rate were lowered.