Thermophysical properties of inorganic waste-based phase change composites: an overview

Commercially available phase change materials (PCMs) often face leakage problems, and low thermal conductivity. Efforts are made to mitigate these issues by encapsulating PCMs in an economical and environmentally friendly manner. Current knowledge on novel composites containing PCMs encapsulated with inorganic waste materials is obtained and discussed in this work. The conducted study encompasses a comprehensive analysis of thermophysical properties of inorganic waste based PCMs, i.e. latent heat, thermal conductivity, specific heat capacity, melting range, thermal and cyclic stability. Economic and environmental aspects of waste utilization were also discussed. The majority of analysed papers featured industrial waste materials like steel slag, blast furnace slag, and tailings, with melting temperatures indicating potential use in medium to high-temperature applications. Presented research suggests that combining waste with PCMs holds promise for further exploration and potential integration into the latent thermal energy storage (LTES) system. For instance, combination of dodecyl alcohol with 22.0 wt% carbonized waste tire rubber demonstrated latent heat of 181 kJ kg-1, with the thermal conductivity increase of 2.3 times compared to the pristine PCM. By consolidating the existing knowledge, the study underscores the potential of waste-based composite PCMs to support circular economy by repurposing waste materials for sustainable energy solutions while minimizing environmental impacts. However, it also emphasizes the necessity for further research to facilitate the commercialization of waste-based PCMs.