Experimental study on micro-fin array shapes for enhanced close-contact melting of phase change materials

With the rapid increase in heat flux from microelectronic devices, efficient thermal management solutions for high power applications are urgently required. Close-contact melting (CCM) has emerged as a promising strategy for high power density heat dissipation. However, the coupled effects of melt drainage and interfacial heat transfer induced by microscale heater surface geometries remain poorly understood. This study aims to develop an efficient thermal management strategy by elucidating the heat transfer and flow regulation mechanisms at the CCM interface induced by micro-fin array geometries. Here, micro-fin arrays (rectangular, triangular, and pin) are experimentally investigated, and the effects of fin geometry and height are systematically quantified. The introduction of micro-fins significantly enhances CCM heat transfer, with rectangular fins exhibiting the best overall performance. At a heat flux of 10 W/cm² and a pressure of 0.169 atm, the thermal resistance of the rectangular fin array decreases to 0.09 K·cm²/W, representing an 83.0% reduction compared with the finless case (0.53 K·cm²/W). Meanwhile, the steady-state temperature is reduced to 44.3 °C (superheat <7 °C), corresponding to a 72.4% decrease relative to the finless case superheat. Mechanistically, the enhancement of CCM is governed by a synergistic trade-off between liquid film thermal resistance and drainage resistance. For rectangular fins, heat transfer is dominated by the fin tip, where an ultra-thin liquid film governs the thermal resistance. Moreover, their straight, low-resistance drainage effectively suppresses the thickening of the liquid film. The proposed micro-fin array provides an effective pathway for achieving efficient thermal management in high power applications.