An Experimental Study On The Macroscopic Spray Characteristics Of Biodiesel And Diesel Under Multiple Parameters

Traditional fossil fuels are non-renewable and eventually will be exhausted in decades. In addition, burning fossil fuels generates a large amount of pollutants exacerbating environmental degradation. Therefore, finding an economically viable and sustainable alternative fuel had become an essential issue. Among the various alternative fuels, biodiesel was the most popular. Both the academic and industrial worlds have paid great attention to the biodiesel fuel. This is because biodiesel fuel-produced from animal fats, vegetable oils and discarded biological oil-was a clean and renewable fuel with reduced soot emissions by virtue of its high oxygen content. However, the biodiesel is hardly atomized because of its properties such as higher surface tension and higher viscosity in comparison to conventional diesel. To improve these properties, biodiesel currently blended with diesel. Moreover, biodiesel fuel blends offer significantly higher lubricity and can be used without modification of the engine. The quality of the fuel-air mixture depends on the spray characteristics of biodiesel-diesel blends, which in turn determines the combustion process and emission characteristics. Biodiesel differs from conventional diesel fuel in some characteristics such as spray tip penetration, spray cone angle, spray area and spray volume because of their different microstructure and physical properties.The objective of this study was to investigate the macroscopic spray characteristics of biodiesel derived from drainage oil and its blends with respect to0#diesel (BDO, BD20, BD50, BD80) such as spray tip penetration, average tip velocity at penetration, spray angle, average spray angle, spray evolution process and spray area under different injection pressures (60,70,80,90,100MPa) and ambient pressures (0.1,0.3,0.5,0.7,0.9MPa) using a common rail system in a constant volume chamber. The characteristic data was extracted from the spray images grabbed by a high speed visualization system. The results showed that as the ambient pressure increased, the spray angle increased, while the spray tip penetration and the peak of average tip velocity decreased. As the injection pressure increased, the spray tip penetration, spray angle, spray area and spray volume increased. The increasing blend ratio of biodiesel brought a shorter spray tip penetration and a smaller spray angle compared with those of diesel.