Experimental and numerical study of spray characteristics of modified bio-diesel in various fuel and ambient conditions

In this research, a new combination of bio-diesel, molasses bio-ethanol, and water has been explored. This combination is called Modified Bio-diesel Fuel (MBF) and can be used instead of fossil fuels. To have better insight, macroscopic and microscopic behaviors of MBF spray have been studied. In comparison with fossil fuels, MBF is better at emissions and production cost. Moreover, high cetane number and oxygen content make MBF an interesting fuel in internal combustion engines. Ohnesorge number and Sauter Mean Diameter (SMD) as atomization characteristics have been investigated by applying two-phase Eulerian–Lagrangian approach in CONVERGE software. Employing droplets atomization physics and dimensional analysis, Atomization Index (AI) that is the ratio of square of inertia forces to product of viscous and surface tension forces has been studied as well. By means of this number, level of atomization of the spray can be estimated. Results show the indirect relation between AI number and SMD, that means increasing the AI number leads to the lower SMD and better atomization. Ohnesorge and AI numbers can determine atomization level of the spray while their results come to the same conclusion. In addition, effects of fuel and ambient temperatures on the spray have been explored and results indicate that they do not affect seriously the characteristics of spray. Due to the similarity between spray behavior of MBF and diesel fuel, it seems MBF can be used in diesel engines instead, though its combustion properties should be considered, as well.