Comparative Evaluation of Combustion, Performance, and Emissions of Jatropha Methyl Ester and Karanj Methyl Ester in a Direct Injection Diesel Engine

Biodiesel prepared from different vegetable oils and fats are likely to have some comparative advantages and disadvantages. Two major oil varieties, considered suitable for biodiesel making are Jatropha curcas and Pongamia pinnata . This study targets at making a comparison of the methyl esters of these oils in a diesel engine against diesel fuel. The performances of the fuels was evaluated in terms of thermal efficiency, specific fuel consumption, power output and mean effective pressure, cylinder pressure, rate of pressure rise, and heat release rates. The emissions of carbon monoxide (CO), carbon dioxide (CO 2 ), unburnt hydrocarbon (HC), oxides of nitrogen (NO x ), and smoke opacity with the three fuels were also compared. Both varieties of the oil, after transesterification, exhibit the major properties within acceptable limits of biodiesel standards set by many countries. Karanj methyl ester (KME) performed better than jatropha methyl ester (JME), whereas the shortest ignition delay is observed with JME. Both the esters performed poorer than diesel, but emissions of HC, NO x, and smoke were found to be lower with esters. The three fuels delivered almost the same brake power, even when the indicated power was higher with diesel.