Impact of Biodiesel Addition on Distillation Characteristics and Cetane Index of Diesel Fuels

This paper examines the impact of biodiesel addition on density, viscosity, distillation profile, and cetane index of diesel fuels. Biodiesel has become an important component in the European diesel fuel market. Its addition to diesel alters the distillation profile, which in turn may impact on the cetane index; the latter remains an important parameter for the evaluation of ignition quality of diesel fuels, in combination with the cetane number. In this series of experiments, fifty diesel fuel samples were used (35 automotive diesel samples and 15 heating gasoil samples) as base fuels, to which sunflower oil biodiesel was added at a concentration of 5% volume in the fuel blend. The distillation profile, density, and kinematic viscosity were measured in all base fuels and blends, whereas the cetane indices were calculated from density and distillation measurements. As expected, the results showed increased density and kinematic viscosity due to the biodiesel addition, whereas the front end volatility (10% recovery) and midboiling point (50% recovery) were increased in the blends. On the other hand back end volatility (90% and 95% recovery and final boiling point) was in most cases reduced due to the biodiesel addition. Observed changes in cetane index were insignificant in most cases.