真空条件下液滴闪蒸的非均温建模与分析

为深入揭示液滴在真空环境下的闪蒸机理，建立了真空闪蒸全过程、非均温的传热传质数学模型，获得了各时刻液滴温度场及半径，并能够追踪结冰阶段的相变界面位置.通过开展液滴闪蒸的实验研究，观察了相变前后液滴的形态变化，并对数值模型进行了验证.基于数学模型，研究了液滴初始半径、初始温度、真空舱压力和结冰过冷度对闪蒸过程的影响规律.结果表明:真空舱压力是影响闪蒸过程的主要因素，且会影响最终平衡温度；初始半径主要影响预冷和冻结时间，而初始温度和结冰过冷度主要只影响预冷时间. 

Modeling and analysis of non-isothermal of droplet flash evaporation in vacuum environment

To reveal the mechanism of droplet flash evaporation in vacuum in depth, a complete non-isothermal model for heat and mass transfer was established. The variation of temperature field and droplet radius was solved exactly, and the accurate position of solid-liquid interface in freezing stage was tracked in real time. Based on the experimental study, the change of droplet shape before and after phase change was observed, and the numerical model was validated to accurately predict the basic features of the process. The effects of initial radius, initial temperature, vacuum pressure and subcooling degree on flash evaporation were studied. Results showed that the vacuum pressure was the major factor in the whole process which would affect the final equilibrium temperature. The initial radius mainly affected the precooling and freezing time, while the initial temperature and subcooling degree only affected the precooling time.