Phase-change materials (PCM) refer to materials provides latent heat during the phase change process in which there are changes of the physical properties but the temperature remains constant. For this kind of performance, the phase change material has a significant application in energy storage, aerospace, military, construction, electricity, refrigeration equipment, clothing and other fields.
Water is a typical phase change material when the temperature is as low as 0 ¡æ, water changes from liquid to solid state (ice). When the temperature is higher than 0 ¡æ water dissolved from solid to liquid. A large amount of cold energy was absorbed during the freezing process while heat was absorbed during the dissolution process.
The thermal conductivity of water during the freezing process was measured withTC3000 thermal conductivity meter in order to obtain the thermal properties of crystals in different crystalline phases. Figure 1 is a screenshot of the experimental results with the software Hotwire. Automatic continuous measurement and different data acquisition frequency in different temperature range were reset in the software.
The results show that, above 0 ¡æ, thermal conductivity decreased when the temperature decreased; in the vicinity of 0 ¡æ when the material entered into crystalline state, the thermal conductivity increased rapidly; When the crystallization is over, the thermal conductivity increased to more than 2.0 W/ (m¡¤K) and continue to increase as the temperature decreased.
