Encapsulation of Phase Change Material with Water-Absorbable Shell for Thermal Energy Storage

To enhance the efficiency of heat transfer fluids, encapsulated phase change materials (PCMs) have been researched as the media for storing and release of a latent heat. The efficiency of thermal energy transportation and the durability of the PCM capsules are quite dependent on the physicochemical and mechanical properties of their shell. Herein, we have prepared the poly(2-hydroxyethyl methacrylate) (pHEMA) encapsulated paraffin-wax sphere as the PCM capsule with high encapsulation ratio, encapsulation efficiency, and thermal storage capability of 97.67, 97.33, and 99.65%, respectively. A hydrous PCM capsule exhibits improved thermal conductivity from ca. 0.26 to 0.47 W/(m·K) at 25 °C in comparison with a dry PCM capsule, and good durability in the melting-freezing cycle test. Our study demonstrates that the encapsulation of phase change material with the hydrous-flexible polymer shell is an effective strategy to enhance the thermal conductivity and durability of PCM capsules.