Flow dynamics mechanisms and thermal hydraulic performance evaluation of triply periodic minimal surface (TPMS) heat exchangers

Heat exchangers (HX) based on triply periodic minimal surface (TPMS) structures provide new opportunities for manipulating internal flow organization and enhancing thermal transport. This study systematically compares the thermohydraulic performance of five representative TPMS HX, including Primitive, I-graph Wrapped Package (IWP), Gyroid, Diamond, and F-Rhombic Dodecahedron (FRD), against a conventional Printed Circuit Heat Exchanger (PCHE) under identical geometric dimensions with 70% porosity. Computational fluid dynamics simulations are performed over a Reynolds number (Re) range of 500–3000 and validated experimentally using additively manufactured prototypes. The results reveal that the continuous three-dimensional curvatures and interconnected pathways of TPMS structures fundamentally alter flow organization by inducing secondary flows, transverse mixing, and thermal boundary layer redevelopment. Different topologies achieve heat transfer enhancement through distinct mechanisms: Gyroid and Diamond promote helical secondary flows through curvature variation, while FRD strengthens flow disturbance through periodic contraction and redirection. Consequently, all TPMS HX exhibit superior heat transfer performance compared with the PCHE. At Re = 500, the FRD HX increases the total heat transfer rate and overall heat transfer coefficient by 69% and 78%, respectively. However, enhanced heat transfer is accompanied by increased hydraulic resistance, with normalized pressure drops ranging from 8.6 Pa/W for IWP to 34.3 Pa/W for FRD. The Gyroid and Diamond HX achieve a favorable balance between flow-induced enhancement and hydraulic penalty. These findings clarify the topology-flow-thermal relationship of TPMS HX and provide physical guidance for the design of compact liquid-cooling systems, particularly for applications such as electronic cooling and battery thermal management.