Supercooling suppression of metal-based microencapsulated phase change material (MEPCM) for thermal energy storage

Due to the advantages of high thermal conductivity, high heat storage density per unit volume and large specific surface area, metal-based microencapsulated phase change material (MEPCM) has a broad application prospect in the field of medium/high-temperature heat storage. However, the problems of thermal expansion and large supercooling seriously restrict its development and application. Our previous research work showed that "double-layer coating, sacrificial inner layer" method can successfully solve the thermal expansion problem of metal-based MEPCM. Based on this method, we aim to further investigate the supercooling suppression of metalbased MEPCM by loading nanoparticles into the core material skillfully when sacrificing the inner layer. Phase change properties of three kinds of MEPCM loaded with different nanoparticles (nano-BN, nano-diamond, and nano-Fe) with the same concentration were compared. It was found that the supercooling suppression effect of nano-Fe was the best. Furthermore, supercooling suppression effect of nano-Fe with different concentrations was compared. The results demonstrated that nano-Fe with a concentration of 0.9% showed the best supercooling suppression effect. In addition, supercooling suppression effect of different particle sizes was compared. The results showed that the supercooling degree of MEPCM decreased by 41.5% and 5.6% when nano-Fe with a particle size of 50 nm and 100 nm was loaded, respectively, indicating that nano-Fe with the particle size of 50 nm is more effective than that of 100 nm. Finally, supercooling suppression effect of different coating methods was compared. The results showed that the supercooling suppression effect of "double-layer coating, sacrificial inner-layer" is much better than that of single-layer coating.