Superhydrophobic Surfaces: Exploiting Microscale Roughness on Hierarchical Superhydrophobic Copper Surfaces for Enhanced Dropwise Condensation (Adv. Mater. Interfaces 3/2015)

Recently there have appeared multiscale lotus-leaf-like superhydrophobic surfaces that can enhance dropwise condensation in well-tailored supersaturation conditions. However, designs of most biomimetic surfaces were not driven by the understanding of underlying physical mechanisms. We report energy-based analysis of growth dynamics of condensates from surface cavities. As observed in condensation experiments, these textured surfaces with two tier roughness are superior to flat or solely nanotextured surfaces in spatial control of condensate droplets. To understand the role of condensate state transition in enhancing condensation heat transfer, we considered adhesion energy, viscous dissipation and contact line dissipation as the main portion of resistant energy that needs to be overcome by the condensates formed in surface cavities. By minimizing the energy barrier associated with the self-pulling process, we optimized first tier roughness on the hierarchically textured surfaces allowing condensates to grow preferentially in the out-of-plane direction. The nano-roughness of the second tier plays an important role in abating the adhesion energy in the cavities and contact line pinning. From the perspective of molecular kinetic theory, the dual scale engineered surface is beneficial to remarkably mitigating contact line dissipation. This study indicates that scaling down surface roughness to submicron scale can facilitate self-propelled condensate removal.

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Dewetting Transitions of Dropwise Condensation on Nanotexture-Enhanced Superhydrophobic Surfaces

ACS Nano ◽

10.1021/acsnano.5b05607 ◽

2015 ◽

Vol 9 (12) ◽

pp. 12311-12319 ◽

Cited By ~ 57

Author(s):

Cunjing Lv ◽

Pengfei Hao ◽

Xiwen Zhang ◽

Feng He

Keyword(s):

Superhydrophobic Surfaces ◽

Dropwise Condensation

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Rationally 3D-Textured Copper Surfaces for Laplace Pressure Imbalance-Induced Enhancement in Dropwise Condensation

ACS Applied Materials & Interfaces ◽

10.1021/acsami.8b09067 ◽

2018 ◽

Vol 10 (34) ◽

pp. 29127-29135 ◽

Cited By ~ 27

Author(s):

Chander Shekhar Sharma ◽

Christos Stamatopoulos ◽

Reto Suter ◽

Philipp Rudolf von Rohr ◽

Dimos Poulikakos

Keyword(s):

Laplace Pressure ◽

Dropwise Condensation ◽

Copper Surfaces

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Scale Effect on Dropwise Condensation on Superhydrophobic Surfaces

ACS Applied Materials & Interfaces ◽

10.1021/am503629f ◽

2014 ◽

Vol 6 (16) ◽

pp. 14353-14359 ◽

Cited By ~ 42

Author(s):

Ching-Wen Lo ◽

Chi-Chuan Wang ◽

Ming-Chang Lu

Keyword(s):

Scale Effect ◽

Superhydrophobic Surfaces ◽

Dropwise Condensation

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Dropwise condensation on superhydrophobic surfaces with two-tier roughness

Applied Physics Letters ◽

10.1063/1.2731434 ◽

2007 ◽

Vol 90 (17) ◽

pp. 173108 ◽

Cited By ~ 243

Author(s):

Chuan-Hua Chen ◽

Qingjun Cai ◽

Chialun Tsai ◽

Chung-Lung Chen ◽

Guangyong Xiong ◽

...

Keyword(s):

Superhydrophobic Surfaces ◽

Dropwise Condensation

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Fabrication of Superhydrophobic Surfaces on Copper Substrates via Brush Plating Technique

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.834-836.662 ◽

2013 ◽

Vol 834-836 ◽

pp. 662-669 ◽

Cited By ~ 1

Author(s):

Ke Hu ◽

Quan Xin Xu ◽

Xiao Long Yang

Keyword(s):

Large Scale ◽

Superhydrophobic Surfaces ◽

Scale Production ◽

Sliding Angle ◽

Water Contact ◽

Copper Surfaces ◽

Plating Technique ◽

Large Scale Production ◽

Sample Technique ◽

Brush Plating

Superhydrophobic surfaces on metal substrates are often prepared via roughing the surfaces and lowering their surface energy. Composite brush plating technique is developed to prepare superhydrophobic n-SiO2/Ni brush plating composite coating on copper surfaces. Under the better process parameters, the water contact angle of the obtained superhydrophobic surface is approximately 160°, and the water sliding angle is less than 10°. The influences of plating voltage and plating time on the coating surface structure and hydrophobicity were discussed. The surface morphology and chemical composition were characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS).The results show that the prepared surfaces have the appearance of the uniform micron papilla-like structures, which are composed of submicron globular Ni particles covered with n-SiO2nanoscale villiform structures. These hierarchical micro/nanostructures are similar to the lotus leaf and play an important role in gaining superhydrophobicity. It is expected that this sample technique will be widely used for large-scale production of superhydrophobic engineering materials.

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Superhydrophobic Surfaces: Nanograssed Micropyramidal Architectures for Continuous Dropwise Condensation (Adv. Funct. Mater. 24/2011)

Advanced Functional Materials ◽

10.1002/adfm.201190115 ◽

2011 ◽

Vol 21 (24) ◽

pp. 4597-4597

Author(s):

Xuemei Chen ◽

Jun Wu ◽

Ruiyuan Ma ◽

Meng Hua ◽

Nikhil Koratkar ◽

...

Keyword(s):

Superhydrophobic Surfaces ◽

Dropwise Condensation

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Effect of Surface Structure Complexity on Interfacial Droplet Behavior of Superhydrophobic Titanium Surfaces for Robust Dropwise Condensation

Materials ◽

10.3390/ma14154107 ◽

2021 ◽

Vol 14 (15) ◽

pp. 4107

Author(s):

Je-Un Jeong ◽

Dae-Yun Ji ◽

Kwon-Yeong Lee ◽

Woonbong Hwang ◽

Chang-Hun Lee ◽

...

Keyword(s):

Heat Transfer ◽

Heat Exchange ◽

Surface Structure ◽

Surface Structures ◽

Superhydrophobic Surfaces ◽

Dropwise Condensation ◽

Exchange Performance ◽

Droplet Behavior ◽

Titanium Surfaces ◽

Structure Complexity

In general, the dropwise condensation supported by superhydrophobic surfaces results in enhanced heat transfer relative to condensation on normal surfaces. However, in supersaturated environments that exceed a certain supersaturation threshold, moisture penetrates the surface structures and results in attached condensation, which reduces the condensation heat transfer efficiency. Therefore, when designing superhydrophobic surfaces for condensers, the surface structure must be resistant to attached condensation in supersaturated conditions. The gap size and complexity of the micro/nanoscale surface structure are the main factors that can be controlled to maintain water repellency in supersaturated environments. In this study, the condensation heat exchange performance was characterized for three different superhydrophobic titanium surface structures via droplet behavior (DB) mapping to evaluate their suitability for power plant condensers. In addition, it was demonstrated that increasing the surface structure complexity increases the versatility of the titanium surfaces by extending the window for improved heat exchange performance. This study demonstrates the usefulness of DB mapping for evaluating the performance of superhydrophobic surfaces regarding their applicability for industrial condenser systems.

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