Expanded graphite/disodium hydrogen phosphate/sodium acetate trihydrate stabilized composite phase change material for heat storage

摘要

A stabilized composite phase change material for heat storage was synthesized by adding expanded graphite and disodium hydrogen phosphate to sodium acetate trihydrate with the method of vacuum adsorption. The effects of expanded graphite and disodium hydrogen phosphate were experimentally explored and the thermal properties of the composite material were characterized. The experimental results indicated that disodium hydrogen phosphate was an excellent nucleating agent for sodium acetate trihydrate. With addition of 1% disodium hydrogen phosphate, the supercooling degree of sodium acetate trihydrate decreased significantly from over 38°C to about 0.5°C. The addition of expanded graphite was also helpful to ameliorate supercooling of sodium acetate trihydrate. Furthermore, phase separation of sodium acetate trihydrate could be effectively eliminated by adding expanded graphite. Compared with the disodium hydrogen phosphate/sodium acetate trihydrate composite material (without addition of expanded graphite), the heat storage/release time of the expanded graphite/disodium hydrogen phosphate/sodium acetate trihydrate composite material was shorten by 75.3%. With the optimal ingredient proportion of 8% expanded graphite, 1% disodium hydrogen phosphate and 91% sodium acetate trihydrate, the composite material became a stabilized 'solid-solid' phase change energy storage material with excellent thermal performance. Its thermal conductivity was greatly improved, and the phase change latent heat reached 233.5kJ/kg. The supercooling and phase separation phenomenon were no longer observed.