Electrically-controlled crystallization of supercooled sodium acetate trihydrate solution

Abstract

The thermal energy storage, using phase change materials, is a promising approach to solving the mismatch between the demand and supply of heat energy in time and space. The phase change materials, especially the hydrated salts, suffer a lot from the supercooling and phase segregation. This study develops a novel electrical nucleation technology to trigger crystallization of the supercooled Sodium Acetate Trihydrate solution using the tiny direct-current (DC) voltage to achieve the long-term energy storage and demand-side driven smart energy supply. First, a stable supercooling of the Sodium Acetate Trihydrate solution was achieved using the addition of extra water and the phase segregation was significantly reduced by the thickening agent. Then, the supercooled Sodium Acetate Trihydrate solution was electrically triggered by the surface-modified electrode to release the stored latent heat immediately. The Ag electrode with the diameter of over 1.0 mm demonstrated the best electronical triggering performance. After that, the mechanism of the electrical nucleation was analyzed in detail. Finally, a theoretical model of the electrical nucleation of the supercooled Sodium Acetate Trihydrate solution was developed and the effect of supercooling degree on the electrical nucleation was investigated. The research findings herein provide an approach to solving the supercooling issue and achieving the smart energy supply as it is wanted.