Hierarchically 3D-textured copper surfaces with enhanced wicking properties for high-power cooling

Phase change heat transfer devices (PCHTDs) have been considered as an ideal choice for the application of high-power cooling. Wick, as the core of PCHTD, has received extensive attention. In this study, hierarchically 3D-textured copper surfaces (TSs) were fabricated as the potential wicks to meet the needs of high-power cooling in PCHTDs. Laser machining, as an efficient special processing means, was employed to complete the fabrication of TSs with different structural parameters. The capillary performance of the TSs, including capillary rise height and velocity, was evaluated by the infrared thermal imaging method with ethanol as working fluid. In particular, the maximum volumetric flow rate of the textured surfaces due to the capillary wicking was found to dominate the two-phase heat transfer capacity through saturated pool boiling tests. The best two-phase heat transfer performance was achieved by TS75 with the critical heat flux of 173.9 W/cm² and the maximum heat transfer coefficient of 34.6 W/cm²K, which are 1.54 and 5.71 times higher than those of the plain surface. Comparative studies with other capillary structures indicated that TSs have comparable or even better enhanced heat transfer performance, making it a promising wick for the application of high-power cooling devices.