Superior Antidegeneration Hierarchical Nanoengineered Wicking Surfaces for Boiling Enhancement

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.