A Review on High‐Temperature Phase‐Change Materials for Waste Heat Recovery: Advances in Materials, System Integration, and Industrial Sustainability

This paper reviews recent advances in high‐temperature phase‐change materials (PCMs) for waste heat recovery (WHR), focusing on applications above 150°C, which have received less attention than low‐temperature systems. It critically examines material developments, system integration strategies, and sector‐specific uses, aiming to identify pathways for broader industrial adoption. The study uses a systematic approach that combines analysis of thermophysical properties, stability, and thermal conductivity with evaluation of system designs such as cascaded storage, segmented heat exchangers, hybrid configurations, and techno‐economic performance. Findings show notable progress in metallic alloys, molten salts, and composite and nano‐enhanced PCMs, each offering benefits in energy density, responsiveness, and stability. Case studies demonstrate that integrating high‐temperature PCMs into WHR systems can improve energy recovery efficiency by 20%–40%, reduce thermal variability, increase usable energy output, and achieve payback periods of 3–5 years in some applications. However, trade‐offs between cost, durability, and performance remain significant, and no single PCM meets all industrial requirements. The review emphasizes that optimal results depend on codesigning materials and system architecture rather than isolated improvements. Future work should prioritize standardized testing, scalable and corrosion‐resistant encapsulation, and sustainable composite materials to support wider deployment and industrial decarbonization.