Materials Degradation Phenomena in Solid-Liquid Phase Change Materials for Thermal Energy Storage

Importantly, phase change materials (PCM) employ latent heat property for storage and management of thermal energy in various applications. As important as the thermal characteristic of the various PCMs determination for suitability in a particular application area is, so do their individual compositional compatibility with container and encapsulation materials in terms of corrosiveness of PCM with respect to factors such as exposure time and temperature, flow and non-flow condition, and static and dynamic conditions. The basic understanding of how container and encapsulation materials corrosion/degradation mechanisms proceed provides for extended serviceability of the thermal management or storage system. Therefore, this paper has reviewed corrosion/degradation mechanisms of container/encapsulation materials subjected to organic, inorganic and metallic PCMs exposure under isothermal, thermal cycling, dynamic and static conditions. Common materials for containers and encapsulation are carbon steels, copper, aluminium and stainless steels where carbon steels and copper were mostly degraded as a result of PCM corrosive attack. Aluminium is mostly faced with pitting based on galvanic effect of impurities contained while the challenge mostly encountered with stainless steels is alloying element depletion, especially chromium depletion which can change the thermal properties of the fluid. However, stainless steels have shown to be the most resistant to corrosive attacks. Another material with potential for use as container material is for example SiC which is also quite corrosion resistant. Overview of methods so far developed/researched for combating corrosive attacks of PCMs on container/encapsulation materials have been highlighted and recommendations on areas of further research are provided.