Enhanced Moisture Condensation on Hierarchical Structured Superhydrophobic–Hydrophilic Patterned Surfaces

Abstract

Patterned surfaces combining hydrophobic and hydrophilic properties show great promise in moisture condensation; however, a comprehensive understanding of the multiscale interfacial behavior and the further controlling method is still lacking. In this paper, we studied the moisture condensation on a hybrid superhydrophobic−hydrophilic surface with hierarchical structures from micro-to nanoscale. For the first time, we demonstrated the effects of wettability difference and microstructure size on the final condensation efficiency. By optimizing the wettability difference, sub-millimeter pattern width, and microstructure size, maximum 90% enhancement of the condensation rate was achieved as compared with the superhydrophobic surface at a subcooling of 13 K. We also demonstrated the enhanced condensation mechanism by a detailed analysis of the condensation process. Our work proposed effective and systematical methods for controlling and optimizing moisture condensation on the patterned surfaces and shed light on application integration of such promising functional surfaces.

Hierarchically Branched Siloxane Brushes for Efficient Harvesting of Atmospheric Water

“…[22] Structural manipulation provides a possible approach to enhance droplet nucleation on superhydrophobic surfaces by incorporating hydrophilic or hydrophobic domains, as these domains have lower water nucleation energy barriers. [23][24][25][26][27][28][29][30][31][32][33] However, these biphilic surfaces often involve complex geometries requiring precisely geometries design, multiple fabrication steps, and sophisticated equipment that make scaling up difficult and expensive. [34][35][36][37] Herein, instead of relying on structural manipulation, the water-repellent coatings of the superhydrophobic surfaces were tailored in this study to attain rapid droplet nucleation while retaining sufficient repellency to maintain jumping droplet departure.…”

“…FAS was chosen as it is the most used superhydrophobic coating in water condensation research. [26][27][28][29][30][40][41][42][43][44][45] The nanostructure selected for fabricating superhydrophobic surfaces was TiO 2 nanorods (NR) because titanium is used in industrial heat exchangers for its lightweight, superb mechanical strength, and excellent corrosion resistance. [46] The TiO 2 nanorods coated with branched siloxane (Siloxane2-NR) exhibited exceptional droplet nucleation and droplet departure rates compared with the nanorods coated with fluoroalkylsilane (FAS-NR) and linear siloxane (Siloxane1-NR).…”

Asymmetric Condensation Characteristics during Dropwise Condensation in the Presence of Non-condensable Gas: A Lattice Boltzmann Study

“…In recent years, various nonwetting surfaces, thanks to the development in regulating surface micro/ nanostructures and chemistry, have attracted explosive attention and led to significant heat transfer enhancement. 1,2,4 The practical condensation system usually suffers from the influence of non-condensable gas (NCG), which plays a crucial role in dropwise condensation. 2 The influence of NCG on the heat transfer performance of dropwise condensation has been continuously explored by experiments.…”

“…As a highly efficient heat transfer mode, dropwise condensation presents great application potential in heat exchange and energy conversion fields, such as water desalination, power generation, and electronic thermal management. , Since its first report, extensive studies have been devoted to understanding the mechanism of dropwise condensation and enhancing condensation heat transfer. ,, Nonwetting surfaces that enable the condensation droplet to be removed rapidly play a crucial role in achieving highly efficient condensation heat transfer. In recent years, various nonwetting surfaces, thanks to the development in regulating surface micro/nanostructures and chemistry, have attracted explosive attention and led to significant heat transfer enhancement. ,, …”

Design of Nanostructured Surfaces for Efficient Condensation by Controlling Condensation Modes

“…Recently, a variety of biomimetic surfaces are designed and the vapor condensation behavior on these surfaces is studied. Based on experimental observations, the effects of surface texture [ 21 , 22 , 23 , 24 ] and wettability distribution [ 25 , 26 , 27 ] on the condensation process are revealed. It is worth noting that, through imaging experiments, Enright et al studied the condensation process on surfaces with different structure length scales (100 nm to 10 μm) and different wetting properties [ 24 ].…”