Abstract: In order to make hydrated salt phase change materials more suitable for solar energy heat storage, Na₂HPO₄·12H₂O was used as the main heat storage agent, Na₂SO₄·10H₂O, Na₂CO₃·10H₂O, Na₂S₂O₃·5H₂O and CH₃COONa·3H₂O were used as auxiliary heat storage agents, and any three of the four auxiliary heat storage agents were mixed with the main heat storage agent according to the designed ratio, nano-TiO₂, ZnO, Al₂O₃, Na₂SiO₃ and Na₂B₄O₇·10H₂O were selected as nucleating agents to modify the quaternary phase change materials. The data of the samples were analyzed by step cooling curve, DSC, SEM, IR and XRD. The results show that Na₂HPO₄·12H₂O/Na₂CO₃·10H₂O/Na₂SO₄·10H₂O/Na₂S₂O₃·5H₂O is the best combination of PCMs,in which the optimal ratio (mass fraction) is 60%, 10%, 20%, 10% (60/10/20/10), respectively. Among the nucleating agents, zinc oxide has the best effect. When the content of zinc oxide is 10% (mass fraction), the supercooling degree of quaternary PCMs decreases from 3.0 ℃ to 0.2 ℃, the phase change enthalpy increases from 95.11 J/g to 472.39 J/g, the phase transition temperature ranges from 15.44 ℃ to 39.90 ℃ to 50.79 ℃ to 129.64 ℃, and there is no phase separation.

Key words: phase change material, nucleating agent, supercooling degree, energy storage