Mechanism of solid-liquid phase transition in coronal core-shell microcapsules phase change materials: Molecular simulations and microscopic experiments

ZY Liu and X Jin and Y Li and JY Jiang, JOURNAL OF ENERGY STORAGE, 111, 115466 (2025).

DOI: 10.1016/j.est.2025.115466

Thermal energy storage technology, a research hotspot in the field of energy utilization, has garnered widespread attention. Phase Change Materials (PCMs) are particularly notable for their high latent heat and stable phase transition temperatures, enabling the storage and release of thermal energy within a specific temperature range. In this study, methyl laurate, tetradecane, and decanol were selected as PCMs, with diatomite and sepiolite serving as carrier materials, to fabricate composite phase change materials (CPCMs) with superior performance via a vacuum impregnation method. The study reveals that filling the carrier materials with PCMs results in a reduction in surface area and pore volume to varying degrees. The thermal performance evaluation of CPCMs revealed a latent heat value reaching up to 88.98 J/g, an impregnation ratio as high as 46.97 %, and a relative enthalpy efficiency of 102.01 %. The CPCMs exhibited a relative enthalpy efficiency exceeding 98 %, with phase change latent heat loss after freeze-thaw cycles maintained within 17 %, indicating excellent thermal stability and reliability. Additionally, molecular dynamics simulations were employed to model the energy, density, volume, and thermal diffusion properties of the three PCMs during the cooling process. The simulations demonstrated a general decreasing trend in energy, density, volume, and self-diffusion coefficients as temperature decreased, with simulated phase transition temperatures closely aligning with experimental values. Furthermore, the increased peak height of the radial distribution function with decreasing temperature suggests that the molecular structure of the PCMs becomes more ordered upon solidification. The CPCMs developed in this study not only exhibit exceptional thermal storage performance and thermal stability but also overcome the leakage issues associated with traditional PCMs, maintaining shape stability during phase transitions.

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