Engine performance of biodiesel-biodiesel blends at varying engine speeds

Abstract

Biodiesel blends with petroleum diesel have long been experimented on and considered good alternatives to petroleum diesel. Most blends considered biodiesel percentages of 20 and less. This work considered blending B100 of separate biodiesel feedstocks to determine their influence on improving physiochemical properties and engine performance. Palm kernel oil methyl ester (PKOME), Jatropha curcas methyl ester (JCME) and coconut oil methyl ester (COME) were blended with the help of a blending machine at 4000 rpm and run in a VW diesel engine to determine their effect on each other in terms of emissions and engine performance. PKOME & COME were blended in proportions of 100%, 75%, 50% and 25% to determine the best blend for optimum physiochemical properties and engine performance. JCME was also blended with COME in the same proportions. Ten separate test fuels of biodiesel and biodiesel-biodiesel blends were run at engine speeds between 800 rpm to 1 800 rpm to determine influence on engine performance and emissions. In terms of exhaust emissions and fuel consumption, the optimum values were obtained with 75% COME and 25% PKOME with brake-specific energy consumption (BSEC) of 15.4 MJ/kWh, CO (0.39 Vol. %), HC (45 ppm) and NOx (146 ppm). The optimum blend of JCME and COME was in the proportion of 75% JCME and 25% COME with BSEC of 13 MJ/kWh and CO, HC and NOx emissions of 0.24 Vol. %, 65 ppm and 256 ppm respectively. The results show that blending biodiesel of different feedstock can improve CIDI engine performance and exhaust emissions.