A comparative study of different fin designs for enhancing the performance of concrete thermal energy storage

Concrete thermal energy storage (CTES) is gaining increasing attention due to its availability and cost-effectiveness, providing a promising solution to the renewable energy transition. However, technical and design challenges remain, particularly in enhancing the heat transfer performance of CTES for the storage and release of thermal energy. This research investigates the design of CTES systems with various fin designs to improve the heat transfer performance through numerical simulation. An efficient 3D numerical model was developed to accurately predict temperature development and charge/discharge behaviour, with results being validated against existing research. Six fin designs, including longitudinal fins, annular fins, Triply Periodic Minimal Surfaces (TPMS) fins, curved fins, bifurcated fins, and helical fins, were investigated as heat exchanger design configurations. The typical temperature distribution, charging and discharging times, charging and discharging efficiencies, manufacturing costs, and carbon emissions were analysed as performance indicators to evaluate different designs. The TPMS outperforms all other designs, achieving the highest reduction in both charging and discharging times, with reductions of 62% and 77%, respectively. This is not only attributed to the surface area, but also to the increasing contact area between the fin and tube of the TPMS fin design. Additionally, the findings show that utilising fins as heat exchangers may offer comparable or superior performance enhancements compared to improving heat transfer of concrete material. The results of this research are anticipated to provide a basis for further analysis and experimental study to improve the performance of CTES.