Evaporation processes of a fuel droplet under sub- and supercritical ambient conditions have been studied using molecular dynamics (MD) simulations. Suspended n-dodecane droplets of various initial diameters evaporating into a nitrogen environment are considered. Both ambient pressure and temperature are varied from sub- to supercritical values, crossing the critical condition of the chosen fuel. Temporal variation in the droplet diameter is obtained and the droplet lifetime is recorded. The time at which supercritical transition happens is determined by calculating the temperature and concentration distributions of the system and comparing with the critical mixing point of the n-dodecane/nitrogen binary system. The dependence of evaporation characteristics on ambient conditions and droplet size is quantified. It is found that the droplet lifetime decreases with increasing ambient pressure and/or temperature. Supercritical transition time decreases with increasing ambient pressure and temperature as well. The droplet heat-up time as well as subcritical to supercritical transition time increases linearly with the initial droplet size d₀, while the droplet lifetime increases linearly with ${\mathrm{d}}_0^2$. A regime diagram is obtained, which indicates the subcritical and supercritical regions as a function of ambient temperature and pressure as well as the initial droplet size.

使用分子动力学（MD）模拟研究了在亚临界和超临界环境条件下燃料滴的蒸发过程。考虑了蒸发到氮气环境中的各种初始直径的悬浮正十二烷液滴。环境压力和温度都从亚临界值变化到超临界值，从而越过所选燃料的临界条件。获得液滴直径的时间变化并记录液滴寿命。通过计算系统的温度和浓度分布，并与正十二烷/氮二元体系的临界混合点进行比较，可以确定发生超临界转变的时间。蒸发特性对环境条件和液滴尺寸的依赖性被量化。发现液滴寿命随着环境压力和/或温度的增加而降低。超临界转变时间也随着环境压力和温度的升高而减少。液滴的加热时间以及亚临界到超临界的过渡时间随初始液滴尺寸的增加而线性增加d ₀，而液滴寿命随${\mathrm{d}}_0^{\mathrm{2个}}$。获得了状态图，该状态图指示了亚临界和超临界区域随环境温度和压力以及初始液滴大小的变化。