Microencapsulation of sodium sulfate decahydrate composite phase-change energy storage materials

To improve the equivalent specific heat capacity of air-conditioning cooling water systems, the current study focused on the preparation and performance evaluation of inorganic hydrated salt phase-change microcapsules. Herein, a phase change microcapsule with sodium sulfate decahydrate (Na2SO4·10H2O, SSD) composite phase change material as the core and methyl methacrylate as the shell was prepared by the monomer polymerization method. Different ratios of emulsifier and initiator were adopted to obtain the desired hydrophile–lipophile balance value, which resulted in nine different formulations of microcapsules. The optimal core-to-shell ratio of 7:3 exhibited a thermal enthalpy value of 147.8 J g−1, a wrapping ratio of 92%, and particle size of 99% of microcapsules was below 3 μm. Moreover, the as-prepared microcapsules exhibited a smooth and non-sticky surface, and the particles were uniformly dispersed and stably suspended in water. These results demonstrate the potential of as-prepared microencapsulated SSD composite phase-change energy storage materials for cooling water applications.