Roosevelt University, Chemistry, Glendale Heightsi, IL 60139
Engines using B20 (20% biodiesel to 80% petrol diesel) grade biodiesel, sometimes suffer from sodium frosting on the fuel injectors. The goal of this experiment was to determine whether sodium bicarbonate can soluble in mixtures of B20 and fuel injector cleaner and determine if this is the frosting agent. Two different fuel sources of B20 biodiesel was used in this study. A preliminary set of tests were run to obtain API gravity, a measure of the density of a petroleum liquid relative to water, flash point, viscosity, and distillation temperatures of the fuels. The different values for both batches were statistically insignificant and thus an average was taken between the two sets to give an overview of the properties of the B20 biodiesel used in this study. For the frosting studies, fuel injector cleaner (FIC) was mixed with B20 Biodiesel to prepare: 0%,1% , 2%, 4%, 6%, and 10% by volume solutions of ,fuel injector cleaner in B20 Biodiesel. Each 1000ml batch was aged for 1 hour. Following the aging process 5 parts per million (PPM) of sodium bicarbonate to the B20/FIC mixtures at the following temperatures: 50,100,200,250 and 280F; which are all within the range of temperatures of a normally operating diesel engine. After the solvation process was completed, the samples were then analyzed using an FTIR, ICP, and GC/FID. The ICP was used to quantify the amount of sodium in each solution; while the FTIR and the GC/FID were used to look at the changes of structure in the fuel caused by adding sodium bicarbonate. According to ASTM (American society for Testing and Material) standards, biodiesel should contain a maximum of 5ppm Na. It was found that at temperatures ranging from 70 - 280°F, sodium content of the fuels ranged were elevated relative to ASTM standards Na, indicating that the sodium bicarbonate was soluble in all the solutions made. Since sodium bicarbonate is present in functional engines, this can be considered a potential cause for the sodium frosting seen on fuel injectors with diesel engines using B20 fuel. For future studies we would be interested in characterizing the exact compound responsible for the frosting and developing solutions to prevent frosting because of the hindrance it causes on engine performance.
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