Modeling and optimization of condensation heat transfer at biphilic interface

Shang, Yun; Hou, Youmin; Yu, Miao; Yao, Shuhuai

doi:10.1016/j.ijheatmasstransfer.2018.01.108

Cited by 43 publications

(32 citation statements)

References 39 publications

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“…To quantify the near field condensation heat transfer, we calculated the overall surface heat flux as a function of the gap distance, . The overall heat flux is obtained by integrating the heat transfer through individual droplets over the droplet size range [51][52][53] :…”

Section: Bridging Dynamicsmentioning

confidence: 99%

“…where ( , ) is the heat transfer through a single droplet with a radius on a surface having an apparent advancing contact angle (Section S8, Supplementary Information). The nucleation radius is determined using classical nucleation theory and is dependent on the droplet shedding mechanisms [51][52][53] . The radius when droplets start to coalesce, , is determined by the nucleation site density via ≈ 1 4 ⁄ 51 .…”

Section: Bridging Dynamicsmentioning

confidence: 99%

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Near Field Condensation

Yan

Chen

Zhao

et al. 2020

Preprint

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Dropwise condensation represents the upper limit of condensation heat transfer. Promoting dropwise condensation relies on surface chemical functionalization, and is fundamentally limited by the maximum droplet departure size. A century of research has focused on active and passive methods to enable the removal of ever smaller droplets. However, fundamental contact line pinning limitations prevent gravitational and shear-based removal of droplets smaller than 250 µm. Here, we break this limitation through near field condensation. By de-coupling nucleation, droplet growth, and shedding via droplet transfer between parallel surfaces, we enable the control of droplet population density and removal of droplets as small as 20 µm without the need for chemical modification or surface structuring. We identify droplet bridging to develop a regime map, showing that rational wettability contrast propels spontaneous droplet transfer from condensing surfaces ranging from hydrophilic to hydrophobic. To demonstrate efficacy, we perform condensation experiments on surfaces ranging from hydrophilic to superhydrophobic. The results show that near field condensation with optimal gap spacing can limit the maximum droplet sizes and significantly increase the population density of sub-20 µm droplets. Theoretical analysis and direct numerical simulation confirm the breaking of classical condensation heat transfer paradigms through enhanced heat transfer. Our study not only pushes beyond century-old phase change limitations, it demonstrates a promising method to enhance the efficiency of applications where high, tunable, gravity-independent, and durable condensation heat transfer is required.

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Section: Bridging Dynamicsmentioning

confidence: 99%

Section: Bridging Dynamicsmentioning

confidence: 99%

Near Field Condensation

Yan

Chen

Zhao

et al. 2020

Preprint

View full text Add to dashboard Cite

show abstract

“…ðÞ Nr ðÞ dr (11) where q d is the heat flux through an individual droplet and N is the droplet size distribution on the surface. Subsequently, corresponding modifications of dropwise condensation heat transfer model to include more accurate expressions for the heat transfer through an individual droplet [35,[39][40][41][42][43][44][45][46][47][48] and droplet size distribution [14,33,39,43,46,[49][50][51] are developed, for example, the conduction resistance of the liquid droplet, the thermal resistance of a hydrophobic coating, mass transfer on the liquid-vapor interface, and the effect of interface curvature.…”

Section: Basics Of Dropwise Condensationmentioning

confidence: 99%

Advances in Dropwise Condensation: Dancing Droplets

Wen¹,

Ma²

2020

21st Century Surface Science - A Handbook

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Vapor condensation is a ubiquitous phase change phenomenon in nature, as well as widely exploited in various industrial applications such as power generation, water treatment and harvesting, heating and cooling, environmental control, and thermal management of electronics. Condensation performance is highly dependent on the interfacial transport and its enhancement promises considerable savings in energy and resources. Recent advances in micro/nano-fabrication and surface chemistry modification techniques have not only enabled exciting interfacial phenomenon and condensation enhancement but also furthered the fundamental understanding of interfacial wetting and transport. In this chapter, we present an overview of dropwise condensation heat transfer with a focus on improving droplet behaviors through surface design and modification. We briefly summarize the basics of interfacial wetting and droplet dynamics in condensation process, discuss the underlying mechanisms of droplet manipulation for condensation enhancement, and introduce some emerging works to illustrate the power of surface modification. Finally, we conclude this chapter by providing the perspectives for future surface design in the field of condensation enhancement.

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“… 10 , 28 In recent years, approaches to achieve efficient sustained dropwise condensation have been focused on engineering hybrid surfaces with heterogeneous wettability. 29 − 32 By judiciously designing surfaces with optimal geometry and wettability, the advantage of dropwise condensation and filmwise condensation can be integrated on the same surface. Peng et al reported that the condensation heat-transfer performance on the dropwise-filmwise hybrid surface is dependent on the surface subcooling degree, 31 filmwise region width, and surface contact angle.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Dropwise Condensation Heat Transfer on Laser-Ablated Superhydrophobic/Hydrophilic Hybrid Copper Surfaces

Song

Chen

2020

ACS Omega

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Heterogeneous surfaces with wetting contrast have gained extensive attention in recent years because of their potential application in condensation heat transfer enhancement. In this work, we engineered superhydrophobic/hydrophilic hybrid (SHH) surfaces on copper substrates via a laser-ablation process. We demonstrated that the as-fabricated SHH surfaces present dropwise condensation behavior; the condensate droplet growth, departure, and heat transfer performance depend strongly on the spacing of the hydrophilic spot. The surface with the hydrophilic spot spacing of 100 μm (SHH100) exhibits the most efficient dropwise condensation in terms of fast droplet growth rate, efficient coalescence-induced droplet departure, as well as enhanced heat transfer coefficient (HTC) compared to the homogeneous superhydrophobic (SHPo) surface. The mechanism underlying the enhanced condensation heat transfer performance is analyzed. A 12% enhancement on condensation HTC was found was found on SHH100 surface compared with the SHPo surface. Our results provide important insights for the design of hybrid surfaces with wetting contrast for enhancing condensation heat transfer performance in many industrial applications.

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Modeling and optimization of condensation heat transfer at biphilic interface

Cited by 43 publications

References 39 publications

Near Field Condensation

Near Field Condensation

Advances in Dropwise Condensation: Dancing Droplets

Investigation of Dropwise Condensation Heat Transfer on Laser-Ablated Superhydrophobic/Hydrophilic Hybrid Copper Surfaces

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