Fuel economy and environmental characteristics of biodiesel and low sulfur fuels in diesel engines

The effect of biodiesel (rapeseed oil methyl ester, RME) and low sulfur fuels on the fuel consumption and emission characteristics of a diesel engine was investigated. The engine tests were carried out based on the 13-mode ECE-49 procedure. Particulate Matter (PM) distribution was analyzed with the state-of-the-art technique of Scanning Mobility Particle Sizing (SMPS). Compared to the base line diesel fuel, biodiesel emitted 20 to 80 % less specific CO, HC, PM, and aromatic hydrocarbons. The electrical mobility diameter of the majority of PM emitted from biodiesel was found to be in the range of 10 to 100 nanometers. The low sulfur fuel emitted 50 % less specific PM compared to the conventional diesel fuel. The aldehydes emission of biodiesel is much lower compared to fossil fuels. The major deficit of the biodiesel fuel was its higher specific fuel consumption rate that was in the range of 12 % (by weight) higher than the other fuels. A relatively higher NOX emission at high loads was encountered for biodiesel fuel.