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| Study on thermal properties of low temperature phase change |
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Abstract In order to deepen the research on the thermal properties of phase change cold storage materials and reduce the energy consumption of cold storage and select suitable low-temperature phase change cold storage materials, a new type of composite phase change cold storage materials mainly made of modified organic composite salt solutions was prepared in this research. Material SH-7. In order to explore the thermal properties of SH-7 solutions with different concentrations, SH-7 solutions with mass fractions of 5%, 10%, 15%, 20% and 25% were prepared in this paper. The phase change temperature, phase change latent heat, thermal conductivity, specific heat capacity, super-cooling, cooling release time and freeze-thaw cycle stability of the cold storage material were tested, and the thermal diffusion coefficient of the material was calculated. By plotting data charts and comparing the measured data, relevant data were selected to select low-temperature phase change cold storage materials suitable for use in cold storage below 0℃. The results showed that: The change of concentration of SH-7 solution has an important impact on its thermal properties. The phase transition temperature and phase transition latent heat gradually decrease with the increase of concentration of SH-7 solution, and the phase transition temperatures and phase transition latent heat of solutions with 5% and 10% concentration are more suitable; The thermal conductivity decreases with the increase of concentration of the solution; the over-cooling degree of SH-7 solution with different concentrations is within 2.7℃, with the over-cooling degree of SH-7 solution with 5% concentration being the smallest; The cooling release time decreases with the increasing concentration, and the cooling release time of solutions with 5% and 10% concentrations is the longest. After comprehensive comparison and analysis, when the concentration of SH-7 solution is 5%, its thermal properties are the best. The phase transition temperature of the solution is -3.47℃, the phase transition latent heat is 267.5 J/g, the thermal conductivity is 0.5268 W/mK, the thermal diffusion coefficient is 0.1726 mm2/s, the degree of over-cooling is 1.3℃, and the cooling release time is 16.8 min. After 50 freeze-thaw cycles, the phase change temperature and phase change latent heat of the solution did not change significantly, and the super-cooling degree and cooling time of the solution did not change significantly. The low-temperature composite phase change cold storage material has good stability and high practicality. It can be reused. The research results can provide a reference for the research and application of phase change cold storage materials in the field of cold storage.
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Received: 28 October 2024
Published: 03 April 2025
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| Fund:China Postdoctoral Science Foundation |
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2025, Vol. 46 
