The use of bio-fuels has attracted attention as a promising approach to reduce CO2. While many bio-fuels come from food crops, Jatropha which is inedible has been the focus of interest recently. Jatropha oil has, however, high viscosity and low volatility which would influence the emission characteristics and fuel consumption, especially in the low load engine condition. Electrically controlled fuel injection seems to be effective to improve the combustion of such fuels. However, the combustion characteristics of Jatropha fueled diesel engine with a fully electrically controlled fuel injection system which can vary the injection pattern in a wide range have not been investigated. In this study, experimental research has been conducted to investigate the effects of double injections with various injection timings, and amount of after-injection on the combustion, engine performance, and emission characteristics in a high speed, 4-stroke diesel engine fueled with neat Jatropha oil. Retarding main- and after-injection timings significantly reduced the peak combustion pressures and peak heat release rate; slightly reduced ignition delay; and shifted the combustion to the later phase. Retarded double injection timings reduced emissions of NOx, while increasing dust, smoke, CO, CO2, and HC. Large amounts of the fuel in after-injections significantly reduced combustion pressures and rates of heat release at lower and medium loads. In addition, large amounts of the fuel in after-injections reduced thermal efficiency and increased emissions of CO2, CO, smoke, and dust concentration, while reducing HC and NOx emissions.
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