In this study,a heat exchange channel with double helix tube as heat storage and heating medium is proposed.The PCM lumped is encapsulated in the phase change thermal storage unit,meanwhile,the numeri-cal model of the structure is established,and the accuracy of the numerical model is verified by experiments.The application characteristics of different materials in this structure are simulated.The simulation results show that the melting and solidification rate of palmitic acid is obviously higher than that of the three kinds of composite hydrated salt phase change materials,but its actual heat storage and heating efficiency is much lower than that of the three kinds of composite hydrated salt phase change materials.When the heat storage reaches 30000 s,the total heat storage of the three kinds of composite phase change materials is about 14 000 J,while palmitic acid is only 6 500 J.This study will provide reference for developing solar phase change ther-mal storage system with high heat exchange efficiency and high thermal storage density,thus promoting the further development of solar thermal utilization technology.
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