Experimental Evaluation of the Effects of Straight Vegetable Oil, and Blends on the Deposits and Wear of the Fuel Injection Equipment

Over the last couple of decade, biofuels have shown a lot of promise in terms of relatively higher combustion efficiency and lower emissions vis-à-vis conventional fuels. If mineral diesel is to be replaced by an alternate fuel in existing IC engines, compatibility of the fuel injection equipment (FIE) with these new fuels need to be ascertained because engine performance, combustion and emission characteristics are greatly affected by the FIE. It is reported that FIE components face issues such as injector deposits, injector blockage and pump plunger wear with biofuels. To experimentally investigate the compatibility of FIE with biofuels, a fuel injection simulator was developed to experimentally simulate the engine conditions as closely as possible, outside the engine environment, without the need for combustion of fuel. This simulator was operated for 250 hours with different Karanja oil blends (K100, K20, and K5) and baseline mineral diesel. New fuel pumps and injectors were used for every set of experiment. After every experiment of 250 hours, fuel injector and pumps were dismantled to assess the deposits, wear and surface texture of different components of FIE. Wear was measured by weight loss, dimensional changes and surface texture changes (analyzed by optical microscopy) of the component. For K100, injector blockage was experienced after 185 hours. During inspection, injector nozzle needles using Karanja oil blends showed higher deposits compared to mineral diesel. Dimensional changes of the plunger were highest for K100 compared to mineral diesel. Karanja oil at lower blends provided superior and improved lubricity compared to mineral diesel. In summary, FIE sub-components were damaged to a higher degree with K100, especially pump plunger. Karanja oil blends showed higher deposits on nozzle needle.