Modulation of phase change heat transfer performance in triply periodic minimal surface based porous structures

Solid-liquid phase change processes are recognized as highly potential solutions for thermal energy storage, thermal management and temperature control for significant latent heat capacity and precise temperature regulation capabilities. Nonetheless, the poor thermal conductivity acts as a bottleneck to advancing heat transfer efficiency. Herein, triply periodic minimal surface (TPMS) were employed as thermal conductivity enhancers, and numerical investigates were conducted for the composite phase change materials (CPCMs) with uniform and gradient TPMS structures. Findings suggest that the W-type structure demonstrates significant advantages in liquid fraction distribution, complete melting time, and thermal wall temperature regulation for their high specific surface area and smooth heat transfer pathways. CPCMs with porosity increasing from bottom to top significantly shorten the phase change time but worsen the uniformity of wall temperature distribution. Conversely, CPCMs characterized by a reduction in porosity along the vertical direction from the base to the top exhibit higher thermal resistance and slower phase change rates, while gradient pore density exerts a weaker influence compared to gradient porosity. Furthermore, a dual-gradient porosity structure is further proposed, reducing the complete melting time by 3.69% compared with the uniform case. More importantly, it markedly improves hot-wall thermal uniformity, lowering temperature inhomogeneity by 47.74%. This demonstrates that the dual-gradient design can simultaneously accelerate melting and suppress thermal non-uniformity, highlighting its comprehensive performance advantages.