Numerical Simulation of Palm Biodiesel Droplet Evaporation at Various Temperatures and Pressures

Abstract

This study uses numerical simulations to determine the evaporation characteristics of palm biodiesel droplets under normal gravity at temperatures ranging from 473 to 873 K and pressures ranging from 0.2 to 5 bar. A transient, two-phase, axisymmetric volume of fluid (VOF) model is employed to model transport processes across phases. The palm methyl ester is modelled as a single-component fuel with temperature- and pressure-dependent thermophysical properties. The study compares the obtained evaporation rates with those available in the literature and presents the effects of external parameters in experimental setups. Additionally, the study investigates the effects of changing the oxygen/nitrogen composition of the environment at elevated temperatures. The results show that elevated temperatures enhance the evaporation rate at all pressures and oxygen contents due to significantly enhanced thermal conductivity and droplet surface temperatures, while elevated pressures decrease the evaporation rates. Across the pressure range, evaporation rates decrease by 219%, 213%, and 196% for temperatures of 473, 673, and 873 K, respectively. Furthermore, increasing oxygen concentration in the environment can also increase the evaporation rate; however, the effect is less noticeable with a 6.4% increase at 473 K and more significant with a 27.8% increase at 873 K across the selected oxygen composition range.