The matching effect of the cold-to-hot fluid on the thermohydraulic characteristics of heat exchangers using gyroid-typed triply periodic minimal surfaces.

This article investigates the thermohydraulic performance of cross-flow heat exchangers (HEXs) embedded with gyroid triply periodic minimal surface (TPMS) structures, focusing on optimizing the flow matching between cold and hot fluid passages. Using computational fluid dynamics simulations, the study reveals that the gyroid TPMS induces complex three-dimensional spiral flow patterns—characterized by "merge-split," parallel, and secondary circulation flows—that enhance fluid mixing and heat transfer. The research finds that increasing the cold-to-hot fluid flow rate ratio improves cold-side convection heat transfer but raises pressure drop, with an optimal flow rate ratio around 2.0–4.0 for balanced performance; meanwhile, an equal volume ratio (R_vol = 1.0) between cold and hot fluid domains maximizes heat transfer efficiency. Compared to traditional HEX designs, the gyroid TPMS structure offers approximately 100% higher specific surface area and 150%–225% greater volume-based power density, suggesting significant potential for compact, lightweight, and efficient heat exchanger applications.