Biodiesel (fatty acid methyl ester) is a non-toxic and biodegradable alternative fuel that is obtained from renewable sources. A major hurdle in the commercialization of biodiesel from virgin oil, in comparison to petroleum-based diesel, is its cost of production, primarily the raw material cost. Used cooking oils or waste cooking oils are economical sources for biodiesel production, which can help in commercialization of biodiesel. However, the products formed during cooking/frying (such as free fatty acids and various polymerized triglycerides) affect the transesterification reaction and the biodiesel properties.
In present experimental investigations, wastecooking oil obtained from restaurant was used to produce biodiesel through transesterification process and the chemical kinetics of biodiesel production was studied. Biodiesel was blended with petroleum diesel in different proportions. The blends were evaluated for the engine performance, emissions and combustion characteristics in a four-stroke, four-cylinder, indirect injection transportation engine vis-à-vis baseline data of petroleum diesel.
It is observed that mass emission of various regulated pollutant species from biodiesel blends is not significantly different from baseline petroleum diesel. Oxides of nitrogen (NOx) emissions increased with increasing concentration of biodiesel in blends, while carbon monoxide (CO) emissions decreased. Brake thermal efficiency of biodiesel blends was observed to be higher as compared to petroleum diesel for all blends. Brake specific fuel consumption (bsfc) and Brake specific energy consumption of all biodiesel blends was found to be lower than petroleum diesel and it was found to be lowest for B20. In addition to this, pressure-crank angle diagram for different biodiesel blends at different engine loads were obtained. Detailed combustion analysis such as rate of heat release, cumulative heat release, rate of pressure rise etc. was done for all biodiesel blends vis-à-vis petroleum diesel and the results are discussed in details.