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.