Abstract
The solubility and stability of 27 biodiesel-diesel fuel-bioethanol blends in the proportions of 5 %, 10 %, 15 %, 20 %, 25 % and 30 % biofuel content was studied. For eight selected blends viscosity, density, surface tension, lubricity, flash point and cold filter plugging point were measured and compared with those of diesel fuel to evaluate their compatibility as compression-ignition (CI) engine fuels. After the second selection, four blends were tested in a CI engine equipped test bench, where the brake specific fuel consumption and engine pollution were determined. For pollution evaluation the emissions of CO, CO2, NOx, HC and smoke have been measured. Due to the used biofuels’ lower heating value compared to that of diesel fuel, the engine’s performances decrease, especially at low engine loads. The studied fuel blends have lower pollution levels, exceptions being CO2 and NOx, where the recorded values are superior to those recorded for diesel fuel. Finally, we tested the fuels in a 524 TD BMW automobile with a four strokes, six cylinder, E28 code and 86 kW Diesel engine, and the obtained results were compared to those of diesel fuel. The engine performances (torque and brake power) were tested in a chassis dynamometer test bench. The investigated blends have the same or very close density and viscosity to standardized diesel fuel. The tests on the chassis dynamometer showed power and torque decrease by up to 5.4 % and 6 %. Vehicle performance and speed test was evaluated over acceleration ability, elasticity and overtaking. Based on the results obtained during the research it can be stated that blends containing 10 % biodiesel, 85 % diesel fuel and 5 % ethanol as well as 25 % biodiesel, 70 % diesel fuel and 5 % ethanol can successfully replace diesel fuel for powering CI engines.
Keywords: Biodiesel, Bioethanol, Fuel Composition, Pollution, Performance