Phase transitions of multi-component fuel droplets under sub- and supercritical conditions

For a multi-component hydrocarbon mixture under supercritical conditions, the mechanism and criterion for transition of dominant mixing mode from evaporation to diffusion are not well established. In this paper, phase processes three-component fuel (5.3 wt% isooctane, 25.8 n-dodecane 68.9 n-hexadecane) droplets in sub- nitrogen environments were studied using molecular dynamics, comparison with those single-component n-hexadecane droplets. The initial diameters 25.5 nm (three-component) 26.5 (single-component), respectively. Based on quantitative Voronoi tessellation, new criterion, which was combination two dimensionless critical values Hc = 0.85 Wc 0.35, proposed determine during fuel-ambient gas mixing. Results indicated that when ambient pressure ranged 2 MPa 10 temperature 750 K 1200 K, density difference between vapor liquid decreased gradually increasing or decreasing temperature. And transitioned diffusion. Increasing did necessarily promote occurrence transition, while accelerated monotonically. Light components increased minimum diffusive zone. A major finding certain pressure, had only but also maximum.