Experimental investigations of dairy scum biodiesel in a diesel engine with variable injection timing for performance, emission and combustion

The waste dairy scum oil containing triglycerides of fatty acids can be a potential candidate for production of biodiesel as an alternative for conventional fossil fuel. The present work investigates the performance, emission and combustion characteristics of dairy scum biodiesel in compression ignition engines corresponding to variable injection timing. The analysis was carried out with four different composition of biodiesel having 10, 20, 30 and 100% of dairy scum oil. Based on brake thermal efficiency and lower emissions, the dairy scum biodiesel with 20% of dairy scum oil (DSB-20) has been considered as the optimum composition. Corresponding to the fuel DSB-20, the highest brake thermal efficiency of 31.87% and lowest brake specific fuel consumption of 0.292 kg/KW.h was achieved for injection 26 degrees before top dead center. The hydrocarbon and carbon monoxide emissions are lowest for DSB-20 with 34 ppm and 0.06% respectively for injection 26 degrees in advance to TDC. For injection 26 degrees before TDC, the cylinder pressure attained 53.12 bar with a pressure rise rate of 4.69 bar for unit crank angle. Similarly both the heat release rate and cumulative heat release rate are highest for DSB-20 with injection 26 degrees before TDC. A better performance, emission and combustion characteristics for DSB-20 with injection 26 degrees before TDC are obtained than that for diesel with injection 23 degrees before TDC. Hence DSB-20 can be successfully used as an alternative to diesel in compression ignition engines with slight more advancement of injection timing.