Nanoarray-Embedded Hierarchical Surfaces for Highly Durable Dropwise Condensation

Abstract

Durable dropwise condensation of saturated vapor is of significance for heat transfer and energy saving in extensive industrial applications. While numerous superhydrophobic surfaces can promote steam condensation, maintaining discrete microdroplets on surfaces without the formation of a flooded filmwise condensation at high subcooling remains challenging. Here, we report the development of carbon nanotube array-embedded hierarchical composite surfaces that enable ultra-durable dropwise condensation under a wide range of subcooling (ΔTsub=8 K–38 K), which outperforms existing nanowire surfaces. This performance stems from the combined strategies of the hydrophobic nanostructures that allow efficient surface renewal and the patterned hydrophilic micro frames that protect the nanostructures and also accelerate droplet nucleation. The synergistic effects of the composite design ensure sustained Cassie wetting mode and capillarity-governed droplet mobility (Bond number<0.055) as well as the large specific volume of condensed droplets, which contributes to the enhanced condensation heat transfer. Our design provides a feasible alternative for efficiently transferring heat in a vapor environment with relatively high temperatures through the tunable multiscale morphology.

Liquid Superspreading on Surface with Microhexagonal Structure Inspired by Rock‐Climbing Fish

“…[1][2][3][4][5][6] Derived from natural inspirations, many fascinating artificial functional surfaces have been designed and produced, showing corresponding functions. [7][8][9][10][11][12][13] The rock-climbing fish (Beaufortia kweichowensis) lives in an environment of strong flowing water and is able to adhere to the rock beds of the stream. [14,15] Therefore, mucus on its body surface is very important for antifouling, antibacterial, and drag reduction.…”