Dropwise Condensation on Inclined Textured Surfaces

Khandekar, Sameer; Muralidhar, K.

doi:10.1007/978-1-4614-8447-9

Cited by 51 publications

(36 citation statements)

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“…Dropwise condensation is a hierarchical and highly transient process [40]. Droplets nucleate with a critical nucleation radius, r min ~ 10 -100 nm for water [41], and a nucleation site density N s .…”

Section: Dropwise Condensation Heat Transfer Theorymentioning

confidence: 99%

Condensate droplet size distribution on lubricant-infused surfaces

Weisensee

Wang

Qian

et al. 2017

International Journal of Heat and Mass Transfer

133

178

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Condensation is a ubiquitous phenomenon in nature and industry. Heat transfer rates during dropwise condensation on non-wetting substrates can be 6-8X higher than heat transfer rates during traditional filmwise condensation on wetting substrates. Dropwise condensation on lubricant-infused surfaces (LIS, or SLIPS) is particularly interesting due to high droplet mobility on these surfaces. To accurately predict heat transfer rates during dropwise condensation, the distribution of droplet sizes must be known. Here we present condensation studies of water on aluminum-based lubricant-infused surfaces with a wide range of lubricant viscosities (12-2717 cSt) to determine droplet size distributions. Through optical imaging and microscopy, we show that the distribution of droplet sizes on LIS is independent of lubricant viscosity, and agrees well with the model developed by Rose for the distribution of droplet sizes on hydrophobic surfaces, especially in the range 10 < r < 100 µm. Using artificial sweeping experiments and numerical modeling, we investigate the dependence of sweeping rates on the distribution of droplet sizes and on average heat transfer rates. The maximum size to which droplets grow before being swept decreases rapidly with only a modest decrease in sweeping period, from 750 to 62 µm. Yet, the distribution of droplet sizes and heat transfer rates are nearly unaffected by the change in sweeping period, due to a relative insensitivity of heat transfer to droplets with radii r > 100 µm due to a high conduction resistance within these droplets. Our work provides an experimental and analytical framework to predict heat transfer and sweeping rates for water condensation on a vertical plate coated with a LIS or SLIPS surface.

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Section: Dropwise Condensation Heat Transfer Theorymentioning

confidence: 99%

Condensate droplet size distribution on lubricant-infused surfaces

Weisensee

Wang

Qian

et al. 2017

International Journal of Heat and Mass Transfer

133

178

View full text Add to dashboard Cite

show abstract

“…The nucleation site density, N s , varies with surface topography and thermodynamic properties of fluid, and extent of subcooling (Rose, 1976;Sikarwar et al, 2013). Based on the experimental data, the nucleation site density was found to be within the range of 10 9 -10 15 m −2 (Khandekar and Muralidhar, 2014;Liu and Cheng, 2015). For the purpose of the heat transfer modeling of drop-wise condensation, we assume the nucleation site density to be at 10 10 m −2 .…”

Section: Mathematical Modelingmentioning

confidence: 99%

Condensation on Surfaces With Biphilic Topography: Experiment and Modeling

2019

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Optimization of the efficiency of the condensers via different surface engineering techniques is a subject of interest due to its wide range of application in thermal management for aerospace vehicles, power generation systems, and etc., which will further result in considerable savings in annual investments and operating costs by millions of dollars. However, the current technologies are lacking either the necessary condensation enhancements or cost-effective, large-scale fabrication method. In this work, we present a new surface topography to enhance drop-wise condensation at low manufacturing costs. These surfaces consist of macro-scale hydrophobic patterns on hydrophilic structures. Due to their high wettability contrast, the biphilic surfaces enhance drop-wise condensation with long-term functionality, and more importantly, they can be easily manufactured in large-scale using conventional methods as no nano-or micro-features are needed.

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“…4 To investigate the mechanism of dropwise condensation, the concept of molecular clustering has been applied and has been studied extensively. 3,10,11 Despite the studies that have been performed on this subject, a physical understanding of the initiation of dropwise condensation is still not complete. 3,12 Recently, the zeta adsorption isotherm (ZAI) theory 13 was applied to investigate the role of molecular clustering under thermal disequilibrium conditions on the initiation of lmwise condensation for a system of heptane vapour adsorbing on a Si surface.…”

Section: Introductionmentioning

confidence: 99%