Temperature Effect on Performance of a Commercial Fuel Filter for Biodiesel Blends with ULSD 2010-01-0473
Biodiesel offers a potentially viable alternative fuel source for diesel automotive applications. However, biodiesel may present problems at colder temperatures due to the crystallization of fatty acid methyl esters and precipitation of other components, such as unreacted triglycerides and sterol glycosides in biodiesel. At lower temperatures, the fuel gels until it solidifies in the fuel lines, clogging the fuel filter, and shutting down the engine. A laboratory-based continuous loop fuel system was utilized to determine the flow properties at low temperatures of biodiesel in B100, B20, and B10 blends for soybean and choice white grease (pig fat) biodiesel fuel. The continuous loop fuel delivery system was designed to be similar to those that can be found in engines and vehicles currently in use, and provided a mechanical pump or an electric pump as a means to simulate systems found in the different types of vehicles. Mass of precipitate on the filter element, fuel flow rate, and pressure across the filter were evaluated in order to determine the flow performance of the filter for each fuel blend and compared to ULSD, which was used as a baseline fuel. For all fuels as a general trend, even for ULSD, as the temperature decreased, the flow rate decreased and the pressure across the filter increased. As biodiesel content increased in the fuel, the amount of precipitate that formed on the filter element also increased. The flow rate and pressure characteristics for soybean B10 and B20 were similar to ULSD, regardless of the pump utilized. This data was also correlated with the cold flow properties, such as pour point, cloud point, and cold filtration plugging point of the fuels. The results of the experimentation show that choice white grease biodiesel, in any blend, would not be a suitable option for use in automotive fuel systems in cold weather conditions, but soybean biodiesel blends of B10 and B20 could be viable options at temperatures as cold at -30°C, while soybean B100 would not.