Analysis of the solidification and phase separation of calcium chloride hexahydrate with different water content by means of X-ray computed tomography

X-ray computed tomography (XCT) is a well-known technology that is quite new to the field of research of non-metallic phase change materials (PCMs) employed in latent thermal energy storages (LTESs). The current work demonstrate the value of XCT, opening unprecedent opportunities to obtain new insights on solid-liquid phase transition. XCT permits to measure accurately volumetric liquid fraction, observing the formation of voids and phase separation, also known as segregation, which is hindering the deployment of salt hydrates, a particular class of PCMs known for their relatively low cost compared to their quite high volumetric energy density. The capabilities of XCT could eventually lead to the understanding of the segregation phenomenon of salt hydrates and in the future, reliable salt hydrates-based LTES will be able to support the energy transition. In the current study, the potential of XCT is shown during the analysis of calcium chloride hexahydrate (CaCl2·6H2O). XCT accuracy and rigorous protocol make it a potential benchmark for new measurement technologies.