Environmental degradation and depletion of fossil fuel reserves are matters of great concern around the world. Diesel is
one of the main transport fuel used in sector and India depends heavily on oil import. Recent concerns over the
environment, increasing fuel prices and shortage of its supply have promoted the interest in development of the
alternative sources for petroleum fuels. It is observed by several researchers that with biodiesel fuelled compression
ignition (CI) engine; the exhaust emission is lower than that of diesel, whereas the NOx emission increases due to the
excess oxygen content and high in-cylinder temperature of biodiesel. So, the exhaust gas recirculation (EGR) technique
may be employed to lower the NOx emissions form CI engines. Although, EGR in CI engine has a number of benefits
on the combustion process and emissions, its effect on the performance of the engine should be critically evaluated.
Keeping this in mind, only the performance characteristics of a double cylinder, water cooled, four stroke, direct
injection compression ignition engine fuelled with jatropha biodiesel -diesel blends (10%, 15%, 20%, 25%, 30% and
50%) have been investigated and compared to mineral diesel with 15% exhaust gas recirculation. The lower blends of
biodiesel increases the thermal efficiency and reduces the fuel consumption. Exhaust gas recirculation improves brake
thermal efficiency and fuel consumption.