Sodium Acetate Trihydrate–Crystallization Inhibitor System for Seasonal Latent Heat Storage

Abstract

Stable supercooling of phase change materials benefits the long-term latent heat storage. Various crystallization inhibitors were adopted to improve the stability of the supercooled sodium acetate trihydrate (SAT) solution, and the supercooling time, cycling stability, and thermal properties were investigated. The supercooling time of the SAT solution was prolonged from 6 h to more than 9 days by acetic acid, ethanol, and glycerin. The supercooled SAT with acetic acid was stable for a long period (>14 days) during the cycling test, indicating the significant effect of acetic acid in maintaining the cycling stability. Acetic acid acts through inhibiting the crystal growth, limiting the crystal size, and/or reducing the water activity of the supercooled solution. The influence of acetic acid on the heat of fusion, onset temperature, and peak temperature of the SAT system was negligible. The system thermal conductivity was slightly reduced from .3698 to .2764 W/(m·K) by acetic acid, requiring further enhancement strategies. The SAT-water-acetic acid mixture has great potential for energy seasonal storage.