Although the inorganic salt hydrate phase change materials (PCMs) such as CaCl₂·6H₂O have promising potential for thermal energy storage in building application, the issue of supercooling has restricted their practical application. In this study, graphene oxide (GO) and SrCl₂·6H₂O as binary nucleation agents were used to modify CaCl₂·6H₂O and reduce its supercooling degree. Compared with pure CaCl₂·6H₂O, the incorporation of graphene oxide (GO)/SrCl₂·6H₂O reduced the supercooling degree to 0.3 °C significantly. In addition, the supercooling degree of modified CaCl₂·6H₂O after 200 thermal cycles was still much lower than that of non-modified CaCl₂·6H₂O. From the results of differential scanning calorimetry (DSC), the latent heat value and phase change temperature of the modified CaCl₂·6H₂O were 207.88 J/g and 27.6 °C, respectively. Aluminum capsules were used to encapsulate the modified PCM and placed inside the composite wallboard. The thermal performances of the composite wallboard with modified PCM were investigated using infrared thermography. Experimental results showed that the average temperature difference between the top and bottom surfaces of modified CaCl₂·6H₂O/wallboard composite after 1 h heating was kept around 15.8 °C, while it was 4.9 °C for the control wallboard. The above test results proved that the modified CaCl₂·6H₂O demonstrated good thermal performance and can be used in buildings to maintain thermal comfort.
Keywords: CaCl2·6H2O; SrCl2·6H2O; graphene oxide; phase change material; supercooling; thermal performance.