Combustion and Emission in a Common Rail Diesel Engine Fueled by Diesel, Palm Oil, Gasoline, and Ethanol Blends under Double-Injection Strategy

Abstract

Palm oil has significant potential for use as fuel for vehicles due to its abundance. However, it is highly viscous and has a high distillation temperature, such that it is difficult to use in engines. This study adds ethanol and gasoline to palm–diesel blends to improve their properties as engine fuel. Diesel, palm oil, gasoline, and ethanol can form transparent, homogeneous, and stable blended fuels at room temperature. D100 (pure diesel), D60P20G10E10 (60% diesel, 20% palm oil, 10% gasoline, and 10% ethanol by volume, denoted by D60P20), and D60P10G20E10 (60% diesel, 10% palm oil, 20% gasoline, and 10% ethanol by volume, denoted by D60G20) were used as test fuels in this study. Under the double injection strategy, the timing of the main injection was kept unchanged while the effects of different pilot injection timings were investigated by using pilot main intervals (PMIs). The results show that the diesel/palm oil/gasoline/ethanol (DPGE) blend as fuel had a longer ignition delay and shorter duration of combustion than D100. The peak heat release rate (PHRR) and peak combustion temperature (PCT) of D60G20 were the highest, followed by D60P20 and D100, at all engine loads. The DPGE blend reduced particulate matter (PM) emission and increased the emission of NOx, which is consistent with the variation in the PCT. With the increase in the PMI, the emission of PCT and NOx by the test fuels decreased slightly while the emission of soot decreased significantly. Of the test fuels considered, D60G20 delivered the best performance in terms of reducing PM emissions and has promising prospects for use in engines.