Bionic Boiling Surface Inspired by Leaf Stomata

Abstract

Enhancing boiling heat transfer performance through innovative surface modifications is a cornerstone of the progression of thermal and nuclear power generation, refrigeration, heat pump, and thermal management applications on the ground and in space. However, large-scale fabrication of modified boiling surfaces with substantially enhanced heat transfer performance remains challenging, necessitating innovative surface structure designs. Herein, we drew inspiration from stomatal transpiration in plant leaves and developed a nickel bionic boiling surface (BBS) featuring finger-like pores using the phase-inversion tape casting method, which is conducive to large-scale manufacturing and customization. The finger-like pores efficiently guide the bubbles, facilitating their timely release owing to the low mass transfer resistance of the straight pore structure. The abundance of nucleation sites on the finger-like pore walls is essential for the optimal onset of nucleate boiling, leading to an improved heat transfer coefficient. Moreover, the capillary force exerted by the micropores surrounding the finger-like pores continuously replenishes water to the nucleation sites, improving wettability and increasing the critical heat flux (CHF). The experimental results demonstrated that the CHF on the BBS reached 242.6 W/cm², representing an increase of 163% compared to that on a plain nickel surface (92.1 W/cm²). The theoretical model utilized to elucidate the intensified boiling heat transfer mechanism of the BBS underscored the importance of enhancing and initiating the wetting and wicking effects, respectively. The findings of the study lay the foundation for a new paradigm in boiling surface design, thereby enhancing the efficiency of a wide range of energy conversion, refrigeration, heating, and thermal management applications.