Thermal performance of sodium acetate trihydrate based composite phase change material for thermal energy storage

Sodium acetate trihydrate (SAT) as a phase change material (PCM) suffers from large supercooling, unclear compatibilities and low thermal conductivity. In this paper, the compatibility of SAT was tested for 270 days with aluminum alloy and copper. The corrosion phenomenon was evaluated by the scanning electron microscope (SEM) images and EDS (energy dispersive spectrum) analyses, which indicated that the corrosion effect could be neglected. Then, SAT modified with the additives of 2 wt% disodium hydrogen phosphate dodecahydrate (DHPD) and 2 wt% carboxyl methyl cellulose (CMC) showed the best performance in reducing supercooling. Finally, a laboratory-scale experiment was conducted to investigate the heat-charging and discharging performance of the heat storage units based on a copper foam/SAT composite PCM. The findings indicated that the heat-charging rate was based mainly on the heat power level, and the composite PCM with fewer thermal conductivity enhancers showed better heat storage performance. The heat discharging process revealed that the heat storage units still had more supercooling than the modified SAT. Based on the results obtained, the copper foam/SAT composite PCM appears to be a promising heat storage material, while the supercooling still needs to be considered in application.