The main objective of this investigation was to study the use of neat methyl esters in DI diesel engine experimentally. Preparation of methyl esters were from non–edible oils of Jatropha curcus, Pongamia pinnata and neem (Azadirachta indica) using transestrification process. The results of the use of neat methyl esters without any modification in the engine parameters and fuel shows reduced performance with increased emissions of NOx compared with diesel. In order to improve the performance with reduced NOx emission, the fuel injection was advanced by 3 CA and a 3% by volume of diethyl ether is added as additive with the fuel. After the above engine and fuel modification, the results shows an appreciable increase in performance and reduced HC, NOx and CO emissions with a slight increase in smoke compared with neat methyl esters without any modifications. Also better performance comparable with diesel with reduced emissions is observed.
Keywords: Jatropha curcus, Pongamia pinnata, neem, transesterification, methyl ester, diethyl ether, engine performance, emissions, crank angle, advanced injection, diesel engines, fuel injection, fuel additives, biodiesel, alternative fuels