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Effects of Oxidation upon Long-term Storage of Karanja Biodiesel on the Combustion and Emission Characteristics of a Heavy-duty Truck Diesel Engine
ISSN: 0148-7191, e-ISSN: 2688-3627
Published July 21, 2021 by SAE International in United States
Biodiesel is a renewable liquid fuel that can be directly used in the diesel engines without any hardware modifications. The presence of unsaturated methyl esters in biodiesel makes it susceptible to oxidation upon long term storage. The oxidized biodiesel affects the durability and life of the engine system components, performance and exhaust emission characteristics through variations in the fuel properties. In the present work, the effects of oxidation of Karanja biodiesel upon long-term storage on the combustion and emission characteristics of a heavy-duty truck diesel engine is studied. The Karanja biodiesel that has ~75% unsaturated methyl esters is stored for one year in a 200 litres steel barrel at room conditions to mimic commercial storage conditions. Engine experiments are carried out at rated torque speed, variable load conditions with aged biodiesel whose results are compared with fresh biodiesel and diesel as reference fuels. The results obtained show that compared to diesel, start of injection of fresh and aged biodiesels are advanced by ~2 degree crank angle and the ignition delay time is shorter. The occurrence of peak pressure is closer to TDC with biodiesels compared to diesel. The fuel injection and combustion characteristics of fresh and aged biodiesels were similar at all the load conditions. Both fresh and aged biodiesels produced higher oxides of nitrogen (NOx) and lower smoke emissions compared to diesel. The exhaust emission characteristics of fresh and aged biodiesels were similar at all the load conditions. Overall, the present study concludes that the variations in the combustion and exhaust emission characteristics of the engine operated with fresh and aged Karanja biodiesel that is stored for one-year under commercial conditions are insignificant.