Influence of cell size and its gradient on thermo-hydraulic characteristics of triply periodic minimal surface heat exchangers

The thermal performance of the triply periodic minimal surface (TPMS) structured heat exchangers (HEs) is highly related to their cell morphology. Unfortunately, current research on the TPMS structured heat exchangers are usually limited to performance comparison between different types of TPMS structures and the objects they researched mainly focused on a single unit or array units with a fixed morphology. In this work, we conduct the first experimental study on the effect of TPMS cell size and its gradient on thermo-hydraulic characteristics of additive manufactured (AMed) pure copper heat exchangers. Geometry measurement shows that the fabricated walls are about 26% thicker than the designed value. The simulation results show that the eccentric flow pattern goes through the entire HE velocity field and presents a rotation tendency. The temperature distribution in the main body presents a certain trend. The smaller the cell size, the more uniform the temperature distribution. The experimental results demonstrate that the effectiveness of cell size = 4 outperforms that of others. As the flow rate increases, the overall heat transfer coefficient and pressure drop increase, while the total thermal resistance decreases. The smaller the cell size, the higher the overall heat transfer coefficient and pressure drop, and the lower the total thermal resistance. The cell size = 6 has the advantage in PEC due to the lowest pressure drop. The cell size = 4 has a greater volume-based power density but also consumes a larger pressure drop per unit length. This study is expected to provide useful design guidelines for the future development of AMed heat exchangers with TPMS structures.