Predicting Temperature Dependent Viscosity for Unaltered Waste Soybean Oil Blended with Petroleum Fuels

Using vegetable oil based alternative fuels for diesel engines has grown in interest over recent years due to the rising cost of petroleum products and instability in the energy marketplace. One of the major hurdles to overcome in using vegetable oil as a diesel fuel is high viscosity. Here, we experimentally determine the viscosity of unaltered waste soybean oil (WSO) blended with petroleum fuels. Three blend viscosity models Arrhenius, Wright, and the ASTM D7152‐05 Standard were evaluated for viscosity prediction accuracy over a temperature range of −10 to 40 °C. Results indicated that the Arrhenius method using volume fractions was the most accurate predictor of viscosity for binary blends made of WSO and diesel (2.31% absolute average deviation) as well as multi‐component blends made from WSO, diesel, kerosene, and gasoline (8.72% absolute average deviation). An intermolecular interaction correction factor was empirically determined for each model in an effort to improve prediction accuracy for the multi‐component blends. Using the correction constants improved the absolute average deviation for the Arrhenius method to 6.85%, 5.87% for the Wright method based on mass fractions, and 9.67% for the ASTM method based on mass fractions. The use of this correlation constant for the Arrhenius method was only helpful for blends containing more that 30% WSO, indicating that molecular interaction behavior only deviates significantly from ideality at these higher WSO fractions.