糖醇基复合相变材料的制备及其光热转换与存储性能研究

To enhance the direct solar-thermal conversion and storage performance of sugar alcohol-based phase change materials （PCMs）and promote their large-scale application in solar thermal energy storage，Xy-in-EG（94 ℃）and Er-in-EG（120 ℃）composite PCMs with high thermal conductivity and excellent light-to-thermal conversion efficiency were prepared using mechanical mixing and melting vacuum adsorption. Xylitol and erythritol served as PCM precursors，while expanded graphite（EG）was used as a thermal conductivity additive. The application of these composite PCMs in solar-thermal direct conversion and storage was systematically investigated. The results show that with 25% EG content，the maximum thermal conductivity of the Xy-in-EG and Er-in-EG composite PCMs reached 4.39 W/ （m·K）and 3.61 W/ （m·K），respectively，which is approximately an order of magnitude higher than that of the original PCMs. When the EG content was 15%，the solar spectral absorptivity of the composite PCMs reached 84.3% and 86.9%，respectively. At this concentration，the composite PCMs achieved stable encapsulation，without issues such as phase transition leakage caused by phase separation during the heating and melting phase transition processes. Furthermore，in solar-thermal direct conversion and storage experiments，the solar-thermal conversion efficiency of Xy-in-15%EG and Er-in-15%EG composite PCMs increased by~63.3% and 79.5%，respectively，compared to commercial xylitol and erythritol PCMs. The photothermal storage rate of Er-in-15%EG was 3.2 times higher than that of commercial erythritol.