Performance Evaluation of Biodiesel-Biodiesel Blends in a dedicated CIDI Engine

Abstract

Biodiesels have long been considered as alternative to petroleum diesel. Characteristics of biodiesel from Palm Kernel Oil Methyl Ester (PKOME), Jatropha Curcas Methyl Ester (JCME) & Coconut Oil Methyl Ester (COME) and their blends have been determined to run in a compression ignition direct injection (CIDI) internal combustion engine. The vegetable oils of Ghanaian origin (PKOME, COME and JCME) were converted to biodiesel by transesterification. Optimum amount of catalysts including 1% H₂SO₄, 1% NaOH and methanol: oil ratio between 6:1 and 8:1 produced the best yields of the biodiesels. The biodiesels were run in a VW diesel engine in an experiment. PKOME and 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. In terms of exhaust emissions and fuel consumption, the optimum values were obtained with 75% COME and 25% PKOME at desirability of 97% 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 JCME and COME was in the proportion of 75% JCME and 25% COME with BSEC of 13 MJ/kW h and CO, HC and NOx emissions of 0.24 Vol. %, 65 ppm and 256 ppm respectively. The optimized blends made engine performance properties close to petroleum diesel (BSEC= 11.8 MJ/kW h, CO=0.43 Vol. %, HC=103 ppm, NOx= 140 ppm). Therefore blends of JCME (75%) and COME (25%) produced better engine performance than petroleum diesel CO by 80% and HC by 58%. The result show that blending biodiesel of different feedstock can improve CIDI engine performance and exhaust emissions.