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Exploring the Benefits of Karanja-Oil-Derived Biodiesel-Water Emulsion as a Potential Fuel for Diesel Engines Operated with High-Pressure Fuel Injection Systems
ISSN: 1946-3936, e-ISSN: 1946-3944
Published July 21, 2023 by SAE International in United States
Citation: Gowrishankar, S., Krishnasamy, A., and Aidhen, I., "Exploring the Benefits of Karanja-Oil-Derived Biodiesel-Water Emulsion as a Potential Fuel for Diesel Engines Operated with High-Pressure Fuel Injection Systems," SAE Int. J. Engines 17(1):2024, https://doi.org/10.4271/03-17-01-0003.
Biodiesel is a suitable alternative to diesel because of its carbon neutrality, renewability, lubricity, and lower pollutant emissions. However, extensive research indicates higher oxides of nitrogen (NOx) emissions with biodiesel. A practical method to combat this problem is utilizing water and biodiesel as emulsions. The effect of biodiesel-water emulsion in high-pressure fuel injection systems is not fully explored in the existing literature. The present study addresses this research gap by utilizing biodiesel-water emulsions in a modified light-duty diesel engine. The governor-controlled injection system was adapted to a fully flexible electronic system capable of high-pressure injection. Unlike other literature studies, the fuel injection timings were optimized with biodiesel-water emulsions to maximize brake thermal efficiency (bte) at every load condition. In a novel attempt, the biodiesel source, i.e., raw Karanja oil (RKO), a triglyceride, was utilized as the surfactant to stabilize the biodiesel-water emulsions containing 6%, 12%, and 18% water. The emulsions reduced the ignition delay and cylinder pressures, with less-intense premixed combustion and a more significant diffusion phase combustion than biodiesel. The emulsions also present a delayed combustion phasing following the injection timing trends. Among the tested emulsions, at 5.08 bar brake mean effective pressure (BMEP), 18% biodiesel-water emulsion resulted in an 18% reduced brake specific fuel consumption (bsfc), 5% increase in bte, 30% and 7% mitigation in NOx and smoke levels, with an increase of 10% and 28% for unburned hydrocarbon (HC) and carbon monoxide (CO) emissions.