Preparation and characteristics of composite phase change material (CPCM) with SiO2 and diatomite as endothermal-hydroscopic material

A kind of CPCM/diatomite composite as endothermal-hydroscopic material was prepared in this paper. The SiO2 of the CPCM was prepared with Tetraethyl orthosilicate by using sol-gel method, and a kind of alkane mixture was used as thermal energy storage material. The diatomite was used as hydroscopic material. The SiO2 prepared by Tetraethyl orthosilicate acted as shell material to prevent the leakage of the melted PCM. Fourier transformation infrared spectroscope (FT-IR) and XRD were used to analyze the chemical structure of the composites, and scanning electronic microscope (SEM) was used to determine the microstructure of the composites. The heat absorbing and solidifying properties and thermal stability of the composites were investigated using the differential scanning calorimeter (DSC) and thermo-gravimetric analyzer (TGA). The results showed that the alkane mixture was encapsulated in the shell of the SiO2 shell, with a mean latent heat of 81.6 kJ/kg. The melting temperature is 27.4 °C and the solidifying temperature is 26.8 °C, which indicates that the composites can be used as a thermal control material. The more the mass ratio of the CPCM is, the more the saturated moisture content of the CPCM/diatomite composites. The CPCM doesn't reduce the hydroscopic properties of the diatomite.