Effects of PCM state on its phase change performance and the thermal performance of building walls

To figure out the effects of PCM location on the thermal performance of building walls, the effects of the state of a kind of salt hydrate phase change material (PCM) on its phase change performance were researched by the differential scanning calorimeter (DSC) tests and the cooling experiments. The three different PCM states are the not-melted state, the partially-melted state, and the fully-melted state, respectively. The experimental results showed that PCM state had great effects on the degree of supercooling and the phase change performance of PCM. When the PCM was in the partially-melted state before cooling, it was able to release the latent heat quickly, while when the PCM was in the fully-melted state before cooling, its degree of supercooling was large. Because the temperature ranges of PCM during the thermal cycles were different when the PCM was placed in different locations in the wall, the PCM location had significant effects on its state, and as a result, on the phase change performance of PCM and the thermal performance improvement of building walls.