Research on the characterization of crystalline growth of calcium chloride hexahydrate heat storage material

Calcium chloride hexahydrate (CCH) has a large latent heat of phase change, a high heat storage capacity and a relatively low cost, which makes it suitable for use in combination with the construction field. However, it has the problem of large supercooling, which limits its development and application. Studying the crystalline growth properties of calcium chloride hexahydrate is essential to comprehending or suppressing supercooling because the degree of supercooling is determined mainly by the room temperature(5–10 °C) melt structure of CCH and the structural factors that drive its supercooling behavior. Using a combination of macroscopic and microscopic research techniques, we explored the two features of the self-crystallization growth behavior of CCH at various initial concentrations and the crystallization growth behavior driven by the external addition of crystal nuclei were explored. The results showed that the water molecule content affects not only the product type but also the growth, development, and regrowth of crystals and crystal morphology. The observation of the triggered crystallization process under different nucleation types showed that the nucleation type affected the crystal growth, and SrCl 2 ·6H 2 O, which had a similar molecular structure, could replace the nucleation of CCH itself and accelerate the crystal growth process. At the same time, NaCl was more difficult to nucleate and inhibited crystal growth. To better understand subcooling and its inhibition, this paper examined the crystallization formation characteristics of CCH at various concentrations, compares and contrasts its crystallization characteristics under various nucleating agents as the triggering nuclei, and investigated the intrinsic mechanism of the nucleus type on its crystallization growth.