Optimal design of multi-layer structure composite containing inorganic hydrated salt phase change materials and cement: Lab-scale tests for buildings

Phase change materials with an ability to store the renewable thermal energy find widespread applications as building materials and temperature control devices. In this study, a lightweight and energy-efficient temperature regulating material based on the sandwich structure of Na 2 SO 4 ·10H 2 O, expanded vermiculite and magnesium oxychloride cement has been reported. The composite material responded in the range 20–40 °C and extended the heating and cooling period of the indoor temperature. The developed material exhibited an improved application performance as compared to the traditional heat preservation materials. Further, the supercooling of Na 2 SO 4 ·10H 2 O/expanded vermiculite was determined to be 1.20 °C, along with shape stability. Different synthesis methods and phase change materials with cement were explored to minimize the degradation of the thermal regulation performance, and the sandwich structure was observed to exhibit the optimal performance. Owing to the low thermal conductivity of Na 2 SO 4 ·10H 2 O/expanded vermiculite and magnesium oxychloride cement, the extended holding time of the indoor temperature was observed. The developed material exhibits significant potential for future applications as self-regulating materials and novel temperature control devices in which the optimal thermo-physical properties are desirable.