Modeling crystallization of a water droplet inside a vacuum chamber

• 1、Department of Refrigeration and Cryogenics, School of Power and Energy, Shandong University

Abstract：Modeling the crystallization of a water droplet inside the vacuum chamber is the first step to model the vacuum spray ice-slurry production system. This paper models the droplet which is transformed from a high temperature to zero temperature, then supercooling liquid, and then to the liquid-solid phase, and finally to the solid phase. Heat and mass transfer occurred rapidly during this process. The modeling results show that the evaporation or the sublimation governs the heat transfer process. Both diffusion model and convection model agrees with the experimental data relatively well, because the heat transferred with convection or conduction is at a much less order of magnitude compared with the latent heat transferred with the phase change. The temperature variation of the droplet during the whole crystallization process is given, which shows that the liquid-solid phase takes up most of the time and is the most important process. The motion of the droplet during the crystallization process is also investigated, with gravity, buoyancy and viscous drag considered. The falling distance obtained from our model is better than what obtained by assuming free falling with only gravity. Results obtained from this paper will provide valuable reference for a better design of the vacuum chamber.

Keywords： Refrigeration vacuum chamber crystallization water droplet ice slurry