Superior Antidegeneration Hierarchical Nanoengineered Wicking Surfaces for Boiling Enhancement

Abstract

Micro‐ and nano‐structured surfaces having high wicking capability enable excellent liquid transport efficiency and have great promise in water desalination, atmospheric water harvesting, biomedical device development, and electronics thermal management applications. However, the poorly understood degeneration of surface wickability during exposure to air represents the main hindrance to societal application of structured surfaces. Here, the authors investigate wicking degeneration on structured surfaces and elucidate the importance of environmental volatile organic compound adsorption from air. Based on their developed mechanistic understanding, the authors design a highly scalable, cost‐effective, and hierarchical structure having both superior wicking capability and antidegeneration performance. Year‐long continuous surface wickability measurements demonstrate a 4100% higher surface wickability durability of this structure when compared to widely used single‐tier surface structures. Pool boiling tests coupled with in situ and in‐liquid optical microscopy are used to characterize the effect of wicking degradation on boiling heat transfer performance. This work demonstrates the previously unidentified coexistence of several dry areas underneath individual bubbles during boiling on highly wicking structured surfaces, resulting in significant augmentation of the three‐phase contact line length. In addition, this work outlines design guidelines for the fabrication of surface wicking structures having high performance and durability.

A Lipid-Inspired Highly Adhesive Interface for Durable Superhydrophobicity in Wet Environments and Stable Jumping Droplet Condensation

“…The wet adhesion between our modeled film and a range of substrates is shown in Figure c. The range of surface energy for the substrates spans from 0 to 140 mJ/m 2 , representing materials ranging from fluorinated polymers, hydrocarbons (20–40 mJ/m 2 ), semiconductors (∼50 mJ/m 2 for graphene), metals (100–300 mJ/m 2 as estimated from the Lifshitz-van der Waals macroscopic approach using known Hamaker constants), and metal oxides (∼100 mJ/m 2 for CuO and Al 2 O 3 ). We first note that high surface energy substrates generally lead to low wet adhesion, which can be qualitatively understood by realizing that water tends to wet the high surface energy substrate .…”

Advances in micro and nanoengineered surfaces for enhancing boiling and condensation heat transfer: a review

“…6A) having high wickability were shown to demonstrate enhancements over a period of 1 year, thus demonstrating durability. 112 Endoscope characterization showed the presence of retained liquid lm in addition to the microlayer for the hierarchical surface (Fig. 6B).…”

Liquid‐Superspreading‐Boosted High‐Performance Jet‐Flow Boiling for Enhancement of Phase‐Change Cooling

“…It especially requires more detailed experimental measurements for ultrafast liquid spreading behavior, [12] as well as an in situ characterization of micro-sized boiling bubbles, although a few visualization technologies have been used for monitoring millimeter-sized bubbles. [13] Herein, we present a micro-/nanostructured Cu (MN-Cu) surface that contains periodic microgroove/pyramid array with rich nanowrinkles around its surface, on which superspreading of FELs highly boosts the liquid re-wetting process. A discontinuous solid-liquid-vapor three-phase contact line is formed on the surface, resulting in ultralow under-liquid bubble adhesion force (≈1.3 μN) in heating condition.…”