Supercooling suppression and thermal behavior improvement of erythritol as phase change material for thermal energy storage

The main aim of this paper is to mitigate the supercooling and improve the heat release performance of erythritol (ET) as phase change material for thermal energy storage using the method of encapsulation and doping additives. The capsules containing ET, thickening and nucleating agent were prepared and various characterization techniques were employed to investigate the structure and thermo-physical properties of the composite, especially the supercooling inhibition and exothermicity improvement. Experimental results reveal that capsulation and adding thickening and nucleating agents have positive influence on the supercooling elimination, heat discharging.ability improvement and thermal stability enhancement. The optimal capsules, with the maximal ET mass percentage of 59.2%, melt at 121.2 degrees C and freeze at 106.4 degrees C with the latent heat of 213.3 J/g and 206.9 J/g, respectively. Due to the improved crystallization kinetics, the degree of supercooling decreased by 83.6% as well as the heat release ratio increased by 52.2% compared to those of pristine ET. The as-prepared capsules have obvious core-shell structure, good compatibility between the shell and core materials. The thermal conductivity is 0.84 W/m K, increased by 29.2% than that of pristine ET. The results of accelerated thermal cycling test indicate that the supercooling, heat release ability and thermal reliability of encapsulated ET changed imperceptibly. In total, the technology of capsulation and adding thickening and nucleating agents can be used to suppress the supercooling and improve the thermal behavior of ET.