Phase Change Materials for Ambient and Cold Thermal Energy Storage: A Comprehensive Review

Abstract Phase change materials (PCMs) enable thermal energy storage with high energy density and nearly isothermal operation, making them well suited for applications that span ambient cooling, refrigeration, transportation, and building energy management. This review examines PCMs with melting temperatures between −30 and 35 °C, a range of increasing relevance for load shifting, demand reduction, and temperature-controlled storage. Organic, inorganic, and eutectic PCMs are evaluated with respect to their thermophysical properties, phase-change behavior, subcooling tendencies, chemical and material compatibility, and long-term stability. Particular attention is given to salt hydrates, their failure mechanisms, and reported strategies to mitigate subcooling and incongruent melting. Metallic PCMs and relevant eutectic formulations are also assessed. A consolidated and critically vetted compilation of PCM properties, including extensive manufacturer data and experimentally reported values, is provided to support material selection. Case studies and commercial demonstrations highlight the practical potential of PCMs for HVAC load shifting, low-temperature refrigeration, and cold-chain transportation. Finally, design considerations for TES systems are reviewed, including encapsulation, enhancement techniques, and operational strategies. The analysis highlights both the promise and challenges of PCM-based storage and provides guidance for researchers and engineers developing next-generation ambient and cold thermal energy storage technologies.