Performance and environmental impact of a compression ignition engine fed with biodiesel and gasoil blends

Since more than one century, energy procurement worldwide has been based on liquid products obtained from refining of crude oil, a not-renewable energy source destined to the exhaustion. It is well known, however, that emissions produced by combustion of fossil fuels, containing CO2, CO, nitrogen and sulphur oxides, Volatile Organic Compounds and particulate, are harmful and cause environmental problems as well. A characterization of performance and pollutant emission levels was then conducted on a compression ignition engine fed with a diesel fuel-biodiesel mixture. In particular, five different blends of the two fuels were studied, and, for each of them, the EGR valve was set on four different opening values. For each of these operating conditions, cylinder pressure fluctuations were measured and heat release rate calculated; moreover, fuel consumption, together with NOx, CO2, HC and particulate matter (PM) levels have been measured. Data obtained from the experimental campaign indicate the biodiesel as an excellent substitute of the diesel fuel from the point of view of energy sources diversification, since its utilization leads to a reduction of HC emission levels equal to about 25% and of PM of about 20%. On the other hand, fuel consumption is increased of about 15% and NOx emission levels of about 30%