Experimental study of pool boiling heat transfer on hybrid surface coupled micro-pin-finned

Abstract

The performance of identical hydrophilic-hydrophobic coupled micro-pin-finned surfaces was evaluated using FC-72 as the working fluid in pool boiling experiments. Three hydrophilic and hydrophobic coupled rectangular copper column surfaces (HH4, HH9, and HH16) were constructed to analyze their boiling heat transfer properties. By integrating the micro-pin-finned surface (PF) and the smooth surface (SS), the impact of various subcoolings (0 K, 15 K, and 25 K) on the critical heat flux (CHF) was explored. Surface HH16 showed the greatest sensitivity to subcooling effects on CHF, followed by HH9 and HH4, respectively. For HH9, the CHF at ΔTsub = 0 K, 15 K, and 25 K, reached 69.6 W·cm−2, 84.2 W·cm−2, and 93.7 W·cm−2, respectively. In comparison to other surfaces (PF, HH4, HH16), the CHF of HH9 climbs by 19.32 %, 8.75 %, and 10.8 % at saturated boiling, respectively. A high-quality camera captured bubble dynamics during the experiments. The results reveal that the hydrophilic and hydrophobic coupled micro-pin-finned copper surface has a greater critical heat flux (CHF) than the standard rectangular micro-pin-finned surface, although heat transfer performance (HTC) drops marginally (both saturated and subcooled boiling). Visual monitoring demonstrates that these coupled surfaces effectively prevent bubble coalescence during subcooled boiling. Additionally, this novel surface design may serve as an effective strategy to reduce drying and delay the onset of boiling crises. The CHF improvement of the HH9 on SS surface was 313.06 %, significantly higher than the 246.17 % of PF on SS, marking a performance increase of 66.89 %. The influence mechanism of the Lattice width coefficient and the Vapor column spacing coefficient on CHF were analyzed. Fluid replenishment and bubble formation behavior were applied to clarify the strengthened heat transfer and CHF triggering mechanism on the surface of the hydrophilic and hydrophobic coupled rectangular micro-pin-finned copper column surface.