Flow boiling heat transfer and pressure drop in gyroid and diamond TPMS channels

As the demand for high-performance heat exchangers under high-heat-flux operating conditions increases, extensive research has been conducted on heat exchangers incorporating triply periodic minimal surface (TPMS) structures. In this study, flow boiling heat transfer coefficients and pressure drops were experimentally investigated in channels with TPMS structures. Two test sections incorporating diamond-based and gyroid-based TPMS structures, respectively, were fabricated as monolithic aluminum components using a 3D printing technique. Each test section consisted of seven TPMS unit cells arranged in series. R-1234yf was used as the working fluid. Experiments were conducted over a mass flux range of 20–80 kg/m²·s, heat fluxes of 5–30 kW/m², and inlet vapor qualities of 0.08–0.91. Single-phase liquid flow experiments were first performed to validate the experimental apparatus. Under single-phase flow conditions, the diamond-based TPMS channel exhibits higher heat transfer performance than the gyroid-based TPMS channel, consistent with previous studies. In contrast, under flow boiling conditions, the gyroid-based TPMS channel shows a pressure drop up to 17.4% higher and a heat transfer coefficient up to 165% higher than those of the diamond-based TPMS channel. These differences are attributed to the highly interconnected pore network of the gyroid structure, which facilitates rapid internal fluid transport and enhances liquid-vapor distribution under flow boiling conditions. Considering both heat transfer enhancement and pressure drop penalty, the results indicate that the gyroid-based TPMS structure provides superior overall performance for evaporators and cooling devices employing TPMS-based heat exchanger channels.