Comparative study of diesel and biodiesel on CI engine with emphasis to emissions—A review

Biodiesel is a renewable, nontoxic, eco-friendly and sustainable alternative fuel for compression ignition engines. In spite of having some application problems, biodiesel, in recent times, being considered as one of the most promising alternative fuels in internal combustion engine. It has been proven that the pollutants in the vehicular emissions have significant impacts on the ecological systems and on the health of human beings. Thus there is an increasing demand on tightening the emission standards of motor vehicles, as well as an ever increasing need for developing means of reducing emissions from in service motor vehicles. Biofuel, such as alcohol and biodiesel, could partly replace petroleum fuel, reduce toxic emissions and more importantly restrain the life-cycle emission of CO. In the present paper, earlier studies have been collected and analyzed. The aim of the present study is to evaluate the feasibility of biodiesel in automobiles, with special emphasis on emission aspects. Few aspects on durability and performance are also included. Evaluation is done on both conventional and CRDI engines, though literature on the latter are few and insufficient when compared to the former. Biodiesel use, when compared to diesel as a fuel, in conventional diesel engines with little or no modification leads to the substantial reduction in particulate matter (PM), hydro carbon (HC) and carbon monoxide (CO) emissions. This is accompanied by a light power loss, increase in fuel consumption and an increase in nitrogen oxide (NOx) emission.