Competitive analysis of scale, interface, and structure effects on thermal behavior and phase transition characteristics of chloride-based CPCMs toward sustainable thermal storage

As the global energy crisis intensifies, solar energy deployment has expanded significantly worldwide. However, solar energy is inherently intermittent and subject to temporal and spatial variability in availability. Consequently, thermal energy storage (TES) systems are essential for enhancing the efficiency, reliability, and dispatchability of solar energy utilization. Among TES materials, chloride-based phase change materials (PCMs) have drawn substantial research interest due to their broad tunable phase change temperature ranges and favorable thermophysical properties. Yet practical implementation is hindered by challenges such as supercooling and phase segregation, prompting the use of porous skeleton matrices for confinement and stabilization. Critically, the pore size, types, and geometric architecture of the skeleton materials collectively govern the thermal behavior and phase transition characteristics of the resulting composite PCMs (CPCMs). Despite their interdependent influence, no systematic comparative study has yet quantified the relative contributions of these three factors to key thermal physical parameters. To address this gap, we conduct a parametric simulation study coupled with multiple linear regression analysis. Rigorously validated regression models reveal that thermal conductivity is predominantly governed by scale effects, whereas specific heat capacity is most sensitive to interfacial effects. Scale effects also exert the strongest influence on both melting temperature and supercooling degree; in contrast, solidification temperature is primarily dictated by interfacial effects. Furthermore, competitive regression analysis of melting and solidification latent heats yields consistent results: scale effects are the dominant determinant of phase change enthalpy across both processes.