Performance and combustion characteristics of a compression ignition engine running on diesel-biodiesel-ethanol (DBE) blends – Part 2: Optimization of injection timing

Abstract

Lately, renewable biofuels could be considered leading candidates for softening society’s liability to fossil derivate fuels and pollutants emission issues. In this paper, taking advantage of compression ignition engine’s better performance, biodiesel and ethanol dawn as renewable commercial fuels in substitution to diesel fuel without the need of geometrical engine modifications. Experimental tests were run in an Euro III multi-cylinder compression ignition engine (MWM 4.10 TCA), fueled with diesel, biodiesel (7 or 15 vol% in diesel fuel) and anhydrous ethanol (up to 20 vol%, by 5 vol% steps) blends. Each diesel-biodiesel-ethanol (DBE) blend, always containing a 1 vol% of original additive in order to ensure blend’s stability, is evaluated for three engine speeds (1500, 1800 and 2100 rpm), so as for two torque conditions (25% and 50%, considering 100% baseline torque conditions established by commercial B7E0 diesel fuel for each engine speed). An investigation is carried for engine’s performance parameters and combustion characteristics, regarding different injection timings for the fuel. The specific fuel consumption could be reduced 4%, while ethanol specific energetic conversion was up to 30% improved at optimized injection timings. On the other hand, the maximum pressure was increased up to 9% and the ignition delay varied 5° just by shifting the start of injection. The fuel injection timing optimization study has also shown a trend of 1° CA injection timing anticipation for each additional 5%vol of ethanol, when the engine was fueled with B15E5, B15E10 and B15E15.