Thermal energy storage properties of carbon nanotubes/sodium acetate trihydrate/sodium monohydrogen phosphate dodecahydrate composite phase-change materials as promising heat storage materials

A novel hydrated salt composite phase change material was prepared. Firstly, the phase transition process of sodium acetate trihydrate (SAT)/ sodium monohydrogen phosphate dodecahydrate (DSP) eutectic salt was studied. And the optimization effect of hydrophilic carbon nanotubes (HCNTs) on the thermal properties of eutectic salt was analyzed. The results showed that the cycle stability of the eutectic salt was the best when the mass ratio of SAT/DSP was 9:1 and the degree of supercooling was 2.5 ℃. With increasing HCNTs mass fraction, the thermal conductivity of the composite showed a linear increase, reaching the highest value of 1.29 W/(m K), which was 182.89% higher than that without HCNTs. The heat storage density exhibited a linear decrease, with a maximum decrease of 5.59%. Finally, the cyclic stability of the HCNTs/SAT/DSP composites was tested, and the results showed that after 200 solid–liquid cycles, each group of materials showed good cycle stability for phase change heat storage system. In this study, the problems of supercooling and phase separation of sodium acetate trihydrate were solved. And its thermal conductivity was significantly strengthened, the results of this study provide a reference for the collaborative adjustment of phase-change materials and thermal storage system components.