Preparation and thermophysical properties of a novel form-stable CaCl2·6H2O/sepiolite composite phase change material for latent heat storage

Abstract

In this work, CaCl2·6H2O/sepiolite was successfully designed and synthesized as a novel form-stable composite phase change material by vacuum impregnation method, using sepiolite as a sustainer and CaCl2·6H2O as phase change material. Scanning electron microscope and Fourier transform infrared spectroscopy measurements display that CaCl2·6H2O is filled into the porous structure of sepiolite by physical interactions. Phase transformation behavior and thermal stability were revealed from differential scanning calorimetry and thermogravimetric analysis, respectively. Results show that the melting enthalpy of the composite phase change material containing 70% CaCl2·6H2O can achieve 87.9 J g−1, and the composite PCM has a good thermal stability in the temperature range from 25 to 100 °C. Meanwhile, the crystal structure of CaCl2·6H2O is maintained in the porous structure of sepiolite observed by X-ray diffraction. It means that sepiolite reduces the super-cooling of CaCl2·6H2O which ensures the good phase change behavior of the composites. These results exhibit that the CaCl2·6H2O/sepiolite composite phase change material possesses high latent heat. Moreover, low cost of the sepiolite enables the composites to be a good candidate for latent heat storage.