Is dropwise condensation feasible? A review on surface modifications for continuous dropwise condensation and a profitability analysis

Ahlers, Marieke; Buck-Emden, Alexander; Bart, Hans‐Jörg

doi:10.1016/j.jare.2018.11.004

Cited by 67 publications

(24 citation statements)

References 112 publications

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“…Dropwise condensation occurs on non-wetting surfaces or partially wetting surfaces (Nouri et al 2012). After nine decades of research on dropwise condensation (Cho et al 2017;Emonsi 1939;Enright et al 2014;Miljkovic and Wang 2013;Schmidt et al 1930), design and fabrication of a surface that can sustain this mode of condensation for a long term have not been successful (Ahlers et al 2018;Ma et al 2019;Oh et al 2018). The main reason for this is that there is no united understanding of dropwise condensation phenomena because of the complexity of the physics involved.…”

Section: Introductionmentioning

confidence: 99%

Development of automated angle-scanning, high-speed surface plasmon resonance imaging and SPRi visualization for the study of dropwise condensation

et al. 2019

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This paper describes the fabrication and testing of a novel angle-scanning surface plasmon resonance imaging (SPRi) instrument. The combination of two stationary mirrors and two angle-controlled mirrors provides high accuracy (up to 10 −3°) and high-speed angular probing. This instrument minimizes the angle-dependent image artifact that arises due to beam walk, which is the biggest challenge for the use of SPRi with angular modulation (AM). In the work described in this paper, two linear stages were employed to minimize the image artifact by adjusting the location of the angle-controlled mirrors and the camera. The SPRi instrument was used to visualize coalescence during dropwise condensation. The results show that the effect of the environment's temperature on reflectance was less than 1% when the incident angle was carefully chosen for SPRi with intensity modulation (IM). This means that condensation visualization can be carried out at ambient temperatures, without the need for a Peltier stage or a thermally controlled condensing surface. The concept of pixel neighboring was employed to assess the probability of noise and the standard error of thin film measurement. Experimental analyses during dropwise condensation show (1) the presence of a thin film with thickness of one monolayer, and (2) surface coverage of 0.71 m 2 /m 2 by the thin film in the area between the droplets. In addition, analyses showed the existence of a dry area at the part of the substrate exposed by coalescence to ambient air. The results of this work undermine the validity of the film rupture theory as the dropwise condensation mechanism.

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Section: Introductionmentioning

confidence: 99%

Development of automated angle-scanning, high-speed surface plasmon resonance imaging and SPRi visualization for the study of dropwise condensation

et al. 2019

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“…Despite the past nine decades of efforts in research and development on DWC enhancement, the industrial implementation studies are very limited. This is due to the lack of fundamental understanding, lower stability, and required maintenance of coatings [170]. In the 1950s, organic substances were used with steam to enhance DWC in a marine condenser and DWC was sustained for two years [171].…”

Section: Porous Coatingmentioning

confidence: 99%

Review of Micro–Nanoscale Surface Coatings Application for Sustaining Dropwise Condensation

et al. 2019

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Condensation occurs in most of the heat transfer processes, ranging from cooling of electronics to heat rejection in power plants. Therefore, any improvement in condensation processes will be reflected in the minimization of global energy consumption, reduction in environmental burdens, and development of sustainable systems. The overall heat transfer coefficient of dropwise condensation (DWC) is higher by several times compared to filmwise condensation (FWC), which is the normal mode in industrial condensers. Thus, it is of utmost importance to obtain sustained DWC for better performance. Stability of DWC depends on surface hydrophobicity, surface free energy, condensate liquid surface tension, contact angle hysteresis, and droplet removal. The required properties for DWC may be achieved by micro–nanoscale surface modification. In this survey, micro–nanoscale coatings such as noble metals, ion implantation, rare earth oxides, lubricant-infused surfaces, polymers, nanostructured surfaces, carbon nanotubes, graphene, and porous coatings have been reviewed and discussed. The surface coating methods, applications, and enhancement potential have been compared with respect to the heat transfer ability, durability, and efficiency. Furthermore, limitations and prevailing challenges for condensation enhancement applications have been consolidated to provide future research guidelines.

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“…The surface roughness is influenced by the surface treatment method, since the wetting behaviour is dependent on the orientation and the texture of roughness [21]. There are numerous choices of mechanical, chemical and electrical methods that are commonly used for surface treatments [23]. The wetting properties on differently treated aluminium surfaces were studied, for example, by Torrisi and Scolaro [24], who applied polishing, sandblasting, chemical etching, laser ablation, ion implantation and deposition of metallic nanoparticles on the surface.…”

Section: Introductionmentioning

confidence: 99%

Static Wettability of Differently Mechanically Treated and Amphiphobic-Coated Aluminium Surfaces

et al. 2020

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Wettability, roughness and surface treatment methods are essential for the majority of practical applications, where liquid–solid surface interactions take place. The present study experimentally investigated the influence of different mechanical surface treatment methods on the static wettability of uncoated and amphiphobic-coated aluminium alloy (AlMg3) samples, specially focusing on the interaction between surface finishing and coating. Five different surfaces were prepared: as-received substrate, polished, sandpapered, fleece-abraded and sandblasted. After characterisation, the samples were spray-coated using an amphiphobic coating. The characterisation of the uncoated and coated samples involved measurements of the roughness parameters and the apparent contact angles of demineralized water and rapeseed oil. The coating was initially characterised regarding its adhesion to the sample and elevated temperature stability. The applied surface treatments resulted in the scattered sample roughness in the range of Sa = 0.3–15.8 µm, water contact angles of θ a p , w = 78°–106° and extremely low oil contact angles. Coating the samples more than doubled the surface roughness to Sa = 13.3–29 µm, whereas the initial surface treatment properties (structure, anisotropy, etc.) were entirely repressed by the coating properties. Coating led the water contact angles to increase to θ a p , w _ c o a t e d = 162°–173° and even more pronounced oil contact angles to increase to θ a p , o _ c o a t e d = 139°–150°, classifying the surfaces as superhydrophobic and oleophobic.

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Is dropwise condensation feasible? A review on surface modifications for continuous dropwise condensation and a profitability analysis

Abstract: Graphical abstract

Cited by 67 publications

References 112 publications

Development of automated angle-scanning, high-speed surface plasmon resonance imaging and SPRi visualization for the study of dropwise condensation

Development of automated angle-scanning, high-speed surface plasmon resonance imaging and SPRi visualization for the study of dropwise condensation

Review of Micro–Nanoscale Surface Coatings Application for Sustaining Dropwise Condensation

Static Wettability of Differently Mechanically Treated and Amphiphobic-Coated Aluminium Surfaces

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