Hybrid Surfaces with Capillary Wick and Minichannels for Enhancement of Phase-Change Immersion Cooling of Power Electronics

The pool boiling heat transfer (phase-change immersion cooling) phenomenon holds significant importance in the energy consumption management of large-power electronics. However, the optimization of surface structure for achieving stable and efficient heat transfer during boiling process remains a significant challenge. Herein, we propose a simplified and direct hybrid surface strategy that combines crossed mini channels and a capillary wick to address the cooling issues faced by high-performance power devices. The copper capillary wick is combined with the crossed mini channel to form a hybrid surface by a simple integrated sintering method. This study investigates the combined effects of different parameters of the capillary wick (average diameter size and powder addition) and minichannels (depth and width) on enhancing the nucleate boiling performance on these hybrid surfaces. The working fluid used in this investigation is HFE-7100. At ΔT_sub = 30 K, the CHF achieved by the hybrid surfaces combining capillary wicks and minichannels can reach 131 W/cm², while the highest HTC is measured at 2.32 W/(cm²·K), both CHF and HTC achieve multiplicative enhancement compared to smooth surfaces. Furthermore, we have developed a CHF prediction model for the hybrid surfaces, which exhibits a prediction error of less than 15%.