Effects of biodiesel-ethanol-diesel blends on the performance indicators of a diesel engine: A study by response surface modeling

The objective of the present study is to evaluate the effect of several variables, including different levels of biodiesel and ethanol in diesel blended fuel (biodiesel-ethanol-diesel blends), engine load and rotational speed, on the performance indicators of a diesel engine. Design of experiments was conducted as central composite rotatable designs using response surface method. The results showed that increasing biodiesel and/or ethanol percentages in the fuel blends caused to reduce the engine brake power. A low level of biodiesel and/or ethanol in the fuel blends could enhance the engine brake thermal efficiency in comparison with the pure diesel fuel or high level of biodiesel and/or ethanol in the diesel fuel blends. The highest value of the engine brake power occurred on the condition for pure diesel, engine load of 100% (full load) and rotational speed of 2800 rpm, whereas the highest value of thermal efficiency was observed at D83B12E5 blended fuel, engine load of 80% and rotational speed of 1900 rpm. However, the specific fuel consumption, with a minimum at the pure diesel, full load and engine rotational speed of 2453 rpm, increased with increment biodiesel and/or ethanol percentage in the fuel blends.