Enhancing heat transfer in concrete thermal energy storage using TPMS fins: Experimental and numerical study

Concrete thermal energy storage (CTES) is a promising technology for large-scale renewable heat storage due to its low cost, durability, and thermal stability. However, the low thermal conductivity of concrete material limits CTES performance, leading to slow charging and discharging and an uneven temperature distribution. This study presents an integrated experimental and numerical investigation for improving the heat transfer efficiency of CTES system through the incorporation of innovative fin designs. Four CTES prototypes were tested, including configurations with Triply Periodic Minimal Surface (TPMS) fins (Primitive and Gyroid topologies). Thermal cycling tests were conducted at temperatures up to 300 °C, and a coupled thermo-mechanical numerical model was developed and validated against experimental observations. The model accurately captured temperature evolution, strain development, and crack formation during repeated charge–discharge cycles. The results highlight that TPMS fins significantly improve temperature uniformity and reduce local thermal gradients compared to the conventional CTES configuration without fins. Specifically, the average temperature of the TPMS-enhanced sample increased by 25.9% relative to the control specimen, demonstrating a substantial enhancement in heat transfer performance. Despite the development of surface cracking, the thermal performance over five charge-discharge cycles remained stable, attributed to the heat transfer pathway and radiative heat transfer across crack interfaces. The findings demonstrate the potential of TPMS fin structures to improve the efficiency and durability of CTES systems, providing a practical pathway for advancing sustainable and cost-effective thermal energy storage technologies for renewable energy applications.