Development of a phase-change material for heat storage in gypsum-based building materials

The aim of this study was to develop a new phase-change material (PCM) for thermal energy storage (TES) in gypsum-based building materials. Expanded vermiculite was used as a base for a coconut oil (CtO)–vermiculite composite PCM. The maximum mass ratio of CtO retained in the vermiculate was found to be 27% for the best particle-size distribution of the vermiculite. The results showed that there were only physical interactions between oil and vermiculite in the composite. The melting temperature and latent heat of the composite were measured as 22·29°C and 24·21 J/g, respectively. Thermal cycling tests showed that there was no significant change in thermal property of the composite after 1000 thermal cycles. A gypsum-based heat-storage material was prepared by mixing the composite with gypsum. The thermal properties, compressive strength and water adsorption of the gypsum–composite mix were then measured. The results showed that the composite could be considered as a promising PCM in gypsum-based building materials for TES applications. This is due to its satisfactory physical, mechanical and thermal properties and good thermal reliability and chemical stability.