The evaporation characteristics and molecular cluster variation of diesel droplets in supercritical environment

作者：Quan Hu, Ruina Li, Dahai Yang, Feifan Liu, Qingcheng Liu, Hua Yue, Meng Yang · 发表于：Physics of Fluids · 年份：2025 · DOI：10.1063/5.0249878 · 被引用次数：5 · 研究领域：Combustion and flame dynamics、Phase Equilibria and Thermodynamics、Advanced Combustion Engine Technologies

In the fuel injection phase of a diesel engine, the temperature and pressure within the cylinder surpass the fuel's critical point, entering a supercritical state. This condition significantly affects the fuel's evaporation and atomization processes within the cylinder. This study conducted an evaporation experiment on diesel droplets under supercritical conditions using a high-temperature, constant-volume droplet evaporation apparatus. A molecular dynamics model was developed to simulate the evaporation of diesel droplets in a nitrogen environment, composed of a mixture of two components: 85.1 mol. % n-dodecane and 14.9 mol. % isooctane. The study focused on the evaporation process in a sub-supercritical environment, analyzing the changes in molecular clusters near the interface during droplet evaporation to elucidate the relationship between droplet evaporation and these molecular clusters. The findings indicate that the lifetime of the droplets decreases with rising ambient temperature and pressure, with the effects being more pronounced in a subcritical environment. The enrichment of nitrogen molecules is 40% in the subcritical environment and 164% in the supercritical environment, suggesting that the enrichment phenomenon of nitrogen molecules is more pronounced under supercritical conditions. At supercritical temperatures, the ambient temperature's influence on the droplet evaporation process is primarily through accelerating the initial heating phase of the droplet. An...