Synchrotron-based X-ray computed tomography analysis of the internal structure and moisture adsorption–desorption behavior of the heat storage and dissipation material HASClay®

HASClay, a porous material designed for heat storage and dissipation, efficiently utilizes low-temperature waste heat below 100 °C. In this study, its internal density structure and moisture adsorption–desorption behavior were investigated using synchrotron radiation–based X-ray computed tomography (CT). X-ray CT analysis revealed distinct high- and low-density regions within HASClay, with the density of both regions increasing as moisture content increased due to water vapor adsorption. In addition, the morphology and distribution of these regions varied depending on the product associated with the temperature during synthesis. Because high-density regions adsorb moisture more efficiently than low-density regions, it was suggested that a key design strategy for improving HASClay is to increase the proportion of high-density regions. Furthermore, HASClay samples subjected to repeated moisture adsorption–desorption cycles exhibited reduced moisture desorption capacity compared with fresh samples. These findings demonstrate that X-ray CT is an effective technique to reveal the water vapor adsorption and desorption process of HASClay based on changes in the internal density distribution.