Feasibility of Complete Substitution of Petroleum Diesel with Biofuels in Diesel Engines: An Experimental Assessment of Combustion, Performance, and Emissions Characteristics

Biodiesel is a good substitute for fossil diesel fuel. However, the high viscosity, low volatility, and poor cold flow properties restrain its use at a high blending ratio or pure in diesel engines. In this regard, blending low-viscosity and high-volatility biofuel with biodiesel is a feasible method to eliminate the disadvantages of biodiesel. It is a cost-effective solution rather than making engine modifications. In this study, the applicability of high-proportion biodiesel (B90) in an existing diesel engine is experimentally investigated by adding methyl acetate and ethyl acetate to biodiesel. An improvement in kinematic viscosity and cold filter plugging point temperature is observed for acetate-added biodiesel fuels. Methyl acetate and ethyl acetate included biofuels result in higher thermal efficiency and lower pollutant emission than sole biodiesel. But their engine performance is still poor compared to diesel fuel. Brake-specific fuel consumption is increased by 24.01–32.29% with acetate-added biodiesel fuels compared to diesel fuel. However, their favorable combustion characteristics increase engine thermal efficiency by up to 3.58% compared to neat biodiesel. CO, HC, NO concentrations, and smoke opacity reduce with acetate-blended biodiesel fuels compared to neat biodiesel. Both methyl acetate and ethyl acetate simultaneously reduce NO emissions and smoke opacity. It is an essential finding of this study, indicating that these oxygenated additives can potentially improve the NOX-PM trade-off in diesel engines.