Migration and phase change phenomena and characteristics of molten salt leaked into soil porous system

Abstract

Molten salt is important heat transfer and storage medium in various high temperature industrial systems, but its leakage and pollution have been seldom investigated. In this paper, migration and phase change phenomena and characteristics of molten salt leaked into soil porous system are numerically investigated using volume of fluid model. During the leakage stage, molten salt expands above the soil, migrates inside the soil and begins to solidify, and finally it solidifies as a solid layer during the post-leakage stage. The vertical velocity of molten salt inside the soil linearly decreases near the surface during the leakage stage, so molten salt gradually migrates into the soil, while the whole flow velocity rapidly approaches to zero after leakage. The temperature and heat flux in the soil near the surface both increase during the leakage stage, and then they decrease during the post-leakage stage. Because of solidification, there exist maximum migration radius and migration depth, so the environment pollution can be limited. As the inlet temperature rises, the maximum migration radius and migration depth both increase for low viscosity of molten salt, while the inlet velocity increment only increases the maximum migration radius. As the soil porosity or particle diameter increases, the maximum migration radius decreases, while the maximum migration depth increases.