Condensation on hybrid-patterned copper tubes (I): Characterization of condensation heat transfer

Alwazzan, Mohammad; Egab, Karim; Peng, Benli; Khan, Jamil A.; Li, Chen

doi:10.1016/j.ijheatmasstransfer.2017.05.039

Cited by 112 publications

(89 citation statements)

References 65 publications

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“…The results of the existing simulations (Rose, 2002) and experiments (Alwazzan et al, 2017, Hoenig, and Bonner, 2018, O'Neill, and Westwater, 1984 are also shown in Fig. 6, with good agreement with the predictions of this study.…”

Section: Size-effect Regime Diagramsupporting

confidence: 86%

Direct Simulations of Biphilic-Surface Condensation: Optimized Size Effects

Chen¹,

Modak²,

Kaviany³

et al. 2020

Frontiers in Heat and Mass Transfer

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In dropwise condensation on vertical surface, droplets grow at nucleation sites, coalesce and reach the departing diameter. In biphilic surfaces, when the hydrophobic domain is small, the maximum droplet diameter is controlled by the shortest dimension where the droplets merge at the boundary. Through direct numerical simulations this size-effect heat transfer coefficient enhancement is calculated. Then the 1-D biphilic surface is optimized considering the size-dependent hydrophilic domain partial flooding (directly simulated as a liquid rivulet and using the capillary limit), the subcooling (heat flux) and condenser length effects. The predicted performance is in good agreement with the available experiments.

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Section: Size-effect Regime Diagramsupporting

confidence: 86%

Direct Simulations of Biphilic-Surface Condensation: Optimized Size Effects

Chen¹,

Modak²,

Kaviany³

et al. 2020

Frontiers in Heat and Mass Transfer

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show abstract

“…Droplet nucleation and condensation are ubiquitous phenomena in nature and industry. Over the past century, research has shown that heat transfer rates during steam dropwise condensation on nonwetting (e.g., hydrophobic) surfaces can be 10× higher than widely accepted filmwise condensation on wetting substrates (1)(2)(3)(4). However, the need for nonwetting hydrophobic coatings in achieving dropwise condensation of water is unclear.…”

Section: Introductionmentioning

confidence: 99%

Dropwise condensation on solid hydrophilic surfaces

et al. 2020

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Droplet nucleation and condensation are ubiquitous phenomena in nature and industry. Over the past century, research has shown dropwise condensation heat transfer on nonwetting surfaces to be an order of magnitude higher than filmwise condensation heat transfer on wetting substrates. However, the necessity for nonwetting to achieve dropwise condensation is unclear. This article reports stable dropwise condensation on a smooth, solid, hydrophilic surface ( a = 38°) having low contact angle hysteresis (<3°). We show that the distribution of nano-to micro-to macroscale droplet sizes (about 100 nm to 1 mm) for coalescing droplets agrees well with the classical distribution on hydrophobic surfaces and elucidate that the wettability-governed dropwise-to-filmwise transition is mediated by the departing droplet Bond number. Our findings demonstrate that achieving stable dropwise condensation is not governed by surface intrinsic wettability, as assumed for the past eight decades, but rather, it is dictated by contact angle hysteresis.

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“…Some emerging strategies and surface design provide the potential to achieve condensation enhancement by using macrotextures or low-cost commercial materials [68,100,103,104,[115][116][117]. The plain hybrid surfaces, consisting of plain hydrophilic and hydrophobic regions, were proposed to achieve dropwise-filmwise condensation for reducing the droplet departure size [ On such a hybrid surface (Figure 10a), the growing droplets in the hydrophobic regions are removed when they grow large enough to contact with the liquid film in the hydrophilic regions, resulting in a smaller removal size than that of gravitydriven departure.…”

Section: Potential Strategies For Condensation Enhancementmentioning

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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Condensation on hybrid-patterned copper tubes (I): Characterization of condensation heat transfer

Cited by 112 publications

References 65 publications

Direct Simulations of Biphilic-Surface Condensation: Optimized Size Effects

Direct Simulations of Biphilic-Surface Condensation: Optimized Size Effects

Dropwise condensation on solid hydrophilic surfaces

Advances in Dropwise Condensation: Dancing Droplets

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