Design, flow characteristics and performance evaluation of bioinspired heat exchangers based on triply periodic minimal surfaces

• Novel cross-flow heat exchangers (HXs) using bioinspired structures are constructed. • Heat transfer performance and flow characteristics of the metal HXs are analyzed. • Simulation models of the HXs are established and validated. • S-D structure shows enormous potential in constructing high-performance compact HXs. Combining additive manufacturing (AM) and bioinspired structures, this study reports the design, fabrication, flow characteristics and heat transfer performance of three novel cross-flow metal heat exchangers (HXs) based on triply periodic minimal surface (TPMS) topologies. Numerical simulations of the TPMS HXs are also validated using associated experimental results for the first time. Results show that, the helically curved channels in the Schwarz-D (S-D) and Gyroid HXs promote flow mixing and induce large-scale bifurcation flow, while the Primitive HX provides basically a through-flow structure. Owing to the complex three-dimensional flow pattern and significantly increased heat transfer surface, the S-D HX provides 41–52% and 4–12% higher heat transfer rates relative to the Primitive HX and Gyroid HX. In addition, the presence of the baffles at the inlet results in similar pressure drops among the three HXs. Compared with the reference HXs reported in the literature, the current Gyroid and S-D HXs show comparable heat transfer performance with significant advantages in terms of pressure drop penalties. Since the surface-to-volume ratio of the TPMS units increases exponentially with decreasing unit size, it is believed that TPMS HXs employing smaller unit size will greatly enhance their compactness and heat transfer performance.