Packing and properties of composite phase change energy storage materials based on SiC nanowires and Na2SO4·10H2O

SiC nanowires were prepared by sol–gel sintering at high temperature, then shaped and encapsulated Na2SO4·10H2O-based composite phase change energy storage materials. The properties of these materials, named PCMs-1, PCMs-3, and PCMs-5, were then investigated. The best-shaped phase change energy storage material was prepared when the content of SiC nanowires added reached 3 mass%. By scanning electron microscopy, PCMs-3 showed that SiC nanowires and Na2SO4·10H2O-based phase change materials have good compatibility with the network layer structure formed by SiC nanowires tightly wrapping the Na2SO4·10H2O-based phase change energy storage materials. The layered phenomenon of Na2SO4·10H2O-based phase change energy storage materials can be effectively reduced in this way, with increased additions of SiC nanowires reducing the degree of undercooling from 2.8 to 1, 0.5 and 0.9 °C with 1, 3 and 5 mass% SiC nanowires, respectively. The thermal conductivity of the phase change materials also improved, with conductivities of PCMs, PCMs-1, 3, 5 being 0.7812, 0.9941, 1.001 and 1.016 W m−1 K−1, respectively. By comparing the latent heat values of PCMs, PCMs-1, 3, 5 phase change energy storage materials thermally cycled 500 times, it was determined that PCMs-3 had the lowest phase change latent heat loss, effectively improving the cycle life of the phase change energy storage materials.