Preliminary design and thermal performance study of a 3D-printed copper heat exchanger with biomimetic tree-shaped fins

Bio-inspired and biomimetic geometries offer great potential for designing next-generation compact heat exchangers (HEXs). However, fabricating these complex structures in copper using additive manufacturing remains highly challenging. This study investigates the thermal performance of a bio-inspired copper HEX featuring a tree branch–inspired fin architecture, fabricated via metal material extrusion (MEX). The novelty lies in the first demonstration of a support-free, MEX-printed copper HEX integrating a helical internal flow channel with tree-shaped fins, validated through a combined experimental and computational fluid dynamics (CFD) approach. Two experimental configurations were evaluated by varying the hot and cold-water flow rates between 10 and 60 L/h under controlled inlet temperatures. The device achieved an apparent thermal efficiency of up to 99% under high cold-flow-rate conditions, while the thermal effectiveness reached values up to 0.32. These performance metrics emphasize the strong dependence on the operational flow conditions, rather than intrinsic geometric performance. Furthermore, excellent agreement between the finite-volume-based CFD simulations and the experimental data was achieved, with a maximum deviation of only 5% in the logarithmic mean temperature difference (LMTD) among all configurations. These results demonstrate the feasibility of manufacturing complex, bio-inspired copper heat exchangers through low-cost MEX, while providing critical insights into the current manufacturing limitations, such as defect induced performance degradation and flow non-uniformity.