为提高糖醇类相变材料（PCM）的直接光热转换与存储性能,促进其在光热储能方面的规模化应用,该文以木糖醇和赤藓糖醇为PCM前驱体,膨胀石墨（EG）为导热添加物,采用机械混合-熔融真空吸附法制备Xy-in-EG（94 ℃）和Er-in-EG（120 ℃）两种不同温区的高导热、高光热转换能力复合PCM,进一步研究所制备复合PCM的光热转换与存储性能。研究结果表明,当EG含量为25%时,两种复合PCM导热系数最大可达到4.39和3.61 W/（m·K）,相较于原始PCM提高约一个数量级;当EG含量为15%时,复合PCM的太阳能光谱吸收率分别达到84.3%和86.9%,且复合PCM达到封装稳定状态,加热熔融相变时不存在相分离引起的相变泄露等问题。对复合PCM进行太阳能光热转换与存储实验表明,复合PCM Xy-in-15%EG和Er-in-15%EG光热转换效率相较于商业PCM木糖醇和赤藓糖醇分别提升了63.3%和79.5%,Er-in-15%EG的光热存储速率与商业赤藓糖醇相比提高了3.2倍。
Abstract
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.
关键词
相变材料 /
导热系数 /
太阳能 /
光热转换 /
热能存储
Key words
phase change materials /
thermal conductivity /
solar energy /
photo-thermal conversion /
thermal energy storage
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基金
国家自然科学基金（52293413;52076161）
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