Thermal properties and cyclic stability of sodium acetate trihydrate composites containing expanded graphite of different sizes

The thermal conductivity, thermal cycling behaviour, and deformation resistance of composite phase change materials (cPCMs) based on sodium acetate trihydrate (SAT) can be effectively improved using expanded graphite (EG). Existing studies have primarily focused on the effect of the expansion ratio on the cPCMs of SAT, and the effect of the particle size of EG on the cPCMs of the SAT has received limited attention. Additionally, more research is required on the degree of supercooling and effective thermal cycles in thermal cycles. In this study, the effects of EG of different sizes (250 and 425 mu m) and proportions (0, 1, 2, 3, 4, 5, and 6 wt %) on the thermal properties and the phase change behaviour of cPCMs in thermal cycles were studied. The results revealed that the 425 mu m EG had a better effect on improving the thermal conductivity of the cPCMs, whereas the 250 mu m EG had a better effect on improving the thermal cycling stability of cPCMs, as evidenced by the sample with 3 wt% of 250 mu m EG completing 512 solidification cycles out of 530 thermal cycles.