Effects of Soybean and Canola Oil–Based Biodiesel Blends on Spray, Combustion, and Emission Characteristics in a Diesel Engine

This paper investigates the effect of biodiesel and biodiesel blends on the macroscopic spray behavior, combustion characteristics, and exhaust emissions of a passenger vehicle diesel engine. In this study, the physical properties, macroscopic spray characteristics, and combustion and emissions characteristics of several fuels such as soybean oil biodiesel, canola oil biodiesel, and its blends were examined. Based on the experimental results, the specific gravity of biodiesel and its blends decreased when the temperature increased, and the tendency of specific gravity was similar for the temperature variation of tested fuels. The dynamic viscosity of biodiesel and its blends decreased as the fuel temperature increased. The viscosity differences between the tested fuels also gradually diminished as the fuel temperature increased. The ignition delay of biodiesel fuels was shortened compared to that of conventional diesel fuel, and the ignition delay was reduced by the increase in the biodiesel blended ratio. The combustion pressure of the biodiesel blended fuel had a similar trend, which was slightly higher than that of conventional diesel fuel. The NOx emissions of biodiesel blended fuels increased; however, this rise in NOx emissions was relatively small compared to the increase in NOx resulting from rising fuel injection pressure. The soot emissions were reduced as the biodiesel blending ratio increased. (C) 2014 American Society of Civil Engineers