Synthesis and characterization of microencapsulated sodium sulfate decahydrate as phase change energy storage materials

• Published in: Applied energy 2019-12, Vol.255, p.113830, Article 113830
• Main Authors: Zhang, Zhishan, Lian, Yadong, Xu, Xibin, Xu, Xiaonong, Fang, Guiyin, Gu, Min
• Format: Article
• Language: English
• Subjects: Microcapsule; Reverse micelle and emulsion polymerization; Silica shell; Sodium sulfate decahydrate; Thermal energy storage
• ISSN: 0306-2619; 1872-9118
• DOI: 10.1016/j.apenergy.2019.113830

•Microencapsulation of Na2SO4·10H2O were fabricated by emulsion polymerization.•The size of microcapsules was tunable by reducing amount of Triton X-100.•Microstructure and chemical structure of microcapsules were presented and analyzed.•Phase segregation of Na2SO4·10H2O has been inhibited by microencapsulation.•Microcapsule by using 1.0 mL of Triton X-100 has a high latent heat of 125.57 J/g. Sodium sulfate decahydrate has been microencapsulated within a silica shell through a novel method of reverse micellization and emulsion polymerization. Tetraethoxysilane and 3-aminopropyl-triethoxysilane were used in conjunction as silicon precursors to form the silica shell, which encapsulated sodium sulfate decahydrate as a phase change material for thermal energy storage. The melting and solidifying temperatures of the microcapsules were measured as 33.6 °C and 6.0 °C, respectively, with associated latent heats of 125.6 kJ/kg and 74.0 kJ/kg. The phase segregation of various hydrate salts was inhibited by the confining effect of the silica mesopores. The size of the microcapsules could be regulated from 500 nm to 28 μm simply by reducing the amount of surfactant (Triton X-100) deployed as a stabilizer. Confined by SiO2 matrix, heat storage properties of the hydrate salts were greatly improved. Sodium sulfate decahydrate microencapsulated within a silica shell is shown to be suitable for application in thermal energy storage.