Li Yang,Yanping Yuan,Nan Zhang,Yanfang Dong,Yafen Sun,Wenhui Ji
Summary To make better use of solar energy, lauric acid/expanded graphite (LA/EG) composite phase change materials (PCMs) were synthesized to collect and store solar energy as latent heat thermal energy. The results of thermal characteristics show that when the mass fraction of EG is 5%, 10%, and 15%, the latent heat of LA/EG is 164.5, 156.9, and 148.0 J/g, and the thermal conductivity is 2.73, 7.98, and 10.54 W/(m·K). Leakage test shows that LA/EG PCMs with EG mass fraction of 10% and 15% are form stable after phase change. One thousand thermal cycles prove good thermal reliability of LA/EG. TG analysis indicates LA/EG PCMs have good thermal stability within operating temperature range. The Ultraviolet-visible spectra reveal that the absorbance of LA/EG composite PCMs would increase as the mass fraction of EG increases. Photothermal conversion experiment results indicate that the photothermal conversion efficiency of LA/EG composite PCMs increases as the mass fraction of EG increases, and the efficiency can reach 95% when the mass fraction of EG is 15%. Moreover, it was also found that the process of photothermal conversion can be accelerated with stronger illumination intensity or smaller heat transfer size. All the results show that the prepared LA/EG PCMs can convert solar energy into thermal energy and store it in the form of latent heat at the same time, which indicates it has promising prospect in the application of solar energy conversion and storage.
Yaguang Yuan,Yanping Yuan,Nan Zhang,Yanxia Du,Xiaoling Cao
Capric–myristic–palmitic acid ternary eutectic mixture (CA–MA–PA) was prepared as phase change material (PCM). A novel composite PCM of CA–MA–PA/expanded graphite (EG) with an optimum mass ratio (CA–MA–PA:EG=13:1) was prepared by uniformly absorbing CA–MA–PA into the porous network structure of the EG. The melting and freezing temperatures of CA–MA–PA/EG composite PCM were measured by differential scanning calorimeter as 18.61 °C and 16.58 °C, respectively, while the melting and freezing latent heats were 128.2 J/g and 124.5 J/g, respectively. The thermal conductivity of the CA–MA–PA/EG composite PCM was measured as 3.67 W/m K and thus the thermal storage and release rates were significantly increased. The thermal cycling test results showed that CA–MA–PA/EG composite PCM has a good thermal reliability. All the above results show that the CA–MA–PA/EG composite PCM is a potential solution for latent heat storage system.
危险品化学品经营许可证（带存储）