Numerical comparison of physical conditions effect on spray behavior of dimethyl ether, biodiesel and diesel fuels

Depleting petroleum resources، increasing costs، and requirements of energy security، have led to an increase interests in renewable fuels، in recent years. Among various alternative fuels، biodiesel and dimethyl ether (DME) fuels are the most popular. In this paper، spray characteristics of diesel and those two fuels have been studied numerically under different physical conditions via the AVL-FIRE software. Injection pressure was kept constant in 50 and 100 MPa and two different pressures were considered for ambient pressure; 1 and 2 MPa. The results were in a good agreement with experimental studies. Spray characteristics such as tip penetration، Sauter mean diameter (SMD) were analyzed. Results showed that in the same physical conditions، DME had the smallest value for spray penetration and diesel had the largest values. In addition، in the case of two different ambient and injection pressures، biodiesel had the largest SMD value and DME has the smallest value in comparison to two other fuels، which means better atomization of DME at same injection and ambient conditions. The spray tip penetration was influenced by ambient pressure in each studying fuels; decreased as the ambient pressure increased، and SMD values decreased as the injection pressure increased.