Thermal characteristics enhancement of MgCl2 phase change material (PCM) for cold thermal energy storage

Currently, the most commonly used cold storage materials are predominantly organic, while inorganic materials are less utilized due to challenges such as high supercooling and phase separation. However, inorganic materials exhibit desirable characteristics, including high latent heat, thermal conductivity, and cost-effectiveness, warranting further exploration of their applicability. This study develops a composite inorganic phase change cold storage material based on MgCl 2 . With a phase change temperature of −33 °C, 17.1 wt% MgCl 2 serves as the primary energy storage agent. The addition of 12.9 wt% NaCl as a temperature regulator adjusts the phase change temperature of the composite material to −37.44 °C. Furthermore, incorporating 4 wt% graphite powder (GP) enhances thermal conductivity by 25%, achieving a value of 0.75 W/(m·K). The inclusion of 1.5 wt% carboxymethyl cellulose (CMC) significantly improves material stability, with no noticeable stratification observed over three months. The addition of 4 wt% GP reduces the degree of supercooling by 54% to 4.3 °C (from 9.45 °C to 4.3 °C). Through optimization of the composite processes, the material achieves a degree of supercooling of 4.3 °C, while maintaining a high latent heat of phase change of 158.84 J/g and a thermal conductivity of 0.65 W/(m·K).