Fabrication and characterization of Sn@Viod@Ceramic phase change macrocapsules for medium-temperature thermal storage

Abstract

Metallic phase change material (PCM) has great application prospects in the field of medium-temperature thermal storage. Macro-encapsulated PCMs with larger core-shell volume ratio and higher heat storage density can solve the millimeter level packaging problem of metallic PCM. However, it is easy to break for the macrocapsules after thermal cycling due to the large volume expansion during phase change. To solve this problem, a novel metal phase change macrocapsule with a thermal expansion void is prepared successfully with Sn powders as PCM core and ceramic powders (Al2O3, AlN, Kaolin or SiC, respectively) as shell raw materials. The voids are introduced by the packing spaces of raw Sn powders as core balls. The results show that the void can accommodate volume expansion of the metal PCM during heat storage and the four kinds of ceramic shells show high corrosion resistance and high compatibility. Thermal analysis indicates that the melting temperature of core (Sn PCM) after 50 cycles is 232.2 °C and the latent heats are 58.0 J/g and 58.3 J/g for melting and crystallization, respectively. Thermal tests confirm that the macrocapsules have excellent oxidation resistance, thermal stability and cycle durability in the practical working temperature range (about 100–300 °C).