Jumping droplet condensation in internal convective vapor flow

Antao, Dion S.; Wilke, Kyle L.; Sack, Jean; Xu, Zhenhua; Preston, Daniel J.; Wang, Evelyn N.

doi:10.1016/j.ijheatmasstransfer.2020.120398

Cited by 12 publications

(10 citation statements)

References 32 publications

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“…17C). 149 The experimental results showed superhydrophobic surface had the highest HTC (z68 kW m −2 K −1 ) at a lower heat ux (z50 kW m −2 ). At a higher heat ux superhydrophobic surface transitioned to ooded condensation mode and exhibited HTC similar to that of lmwise condensation (z26 kW m −2 K −1 ).…”

Section: Nanostructuring Of Additively Manufactured Surfaces For Enha...mentioning

confidence: 87%

“…Coatings with high thermal conductivity can improve performance. 146 Interconnected pores formed through structure fabrication also leads to enhanced wicking 149,150 and can increase lm evaporation contributions as well as bubble departure frequency. A laser-induced uorescence technique with 1 mm diameter tracer particles has been used to characterize liquid velocity inside pores.…”

Section: Nucleation Sites Turbulence and Instability Suppressionmentioning

confidence: 99%

See 1 more Smart Citation

Advances in micro and nanoengineered surfaces for enhancing boiling and condensation heat transfer: a review

et al. 2023

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Section: Nanostructuring Of Additively Manufactured Surfaces For Enha...mentioning

confidence: 87%

Section: Nucleation Sites Turbulence and Instability Suppressionmentioning

confidence: 99%

Advances in micro and nanoengineered surfaces for enhancing boiling and condensation heat transfer: a review

et al. 2023

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“…One approach for enhancing condensation in microchannels is to coat the surface in hydrophobic substance such as Teflon, which transitions the filmwise condensation into dropwise condensation, resulting in enhancements up to 10 times, yet coatings are not always durable (Miljkovic and Wang, 2013;Chen and Derby, 2016;Chen et al, 2017;Antao et al, 2020;Hoque et al, 2022). However, durable hydrophobic coatings remain an active research area, thus condensation processes in industry are filmwise condensation instead of dropwise condensation (Ahlers et al, 2019;Chang et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Visualizing and disrupting liquid films for filmwise flow condensation in horizontal minichannels

et al. 2022

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This paper investigates the effects of hemispherical mounds on filmwise condensation heat transfer in micro-channels. Also investigated were the impacts that spatial orientation of the three-sided condensation surface (i.e., gravitational effects) on steam condensation, where the cooled surfaces were either the lower surface (i.e., gravity pulls liquid towards the condensing surfaces) or upper surface (i.e., gravity pulls liquid away from the condensing surfaces). Two test coupons were used with 1.9-mm hydraulic diameters and either a plain copper surface or a copper surface modified with 2-mm diameter hemispherical mounds. Heat transfer coefficients, film visualization, and pressure drop measurements were recorded for both coupons in both orientations at mass fluxes of 50 kg/m2s and 125 kg/m2s. For all test conditions, the mounds were found to increase condensation heat transfer coefficients by at minimum 13% and at maximum 79%. When the test section was inverted (i.e., condensing surface on the top of flowing steam), minimal differences were found in mound performance, while the plain coupon reduces heat transfer coefficients by as much as 14%. Flow visualization suggests that the mounds enhanced heat transfer due to the disruption of the film as well as by reducing the thermal resistance of the film. Pressure drops followed parabolic behavior with quality, being higher in the mound coupon than the plain coupon. No significant pressure drop differences in the inverted orientation were observed.

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“…The coalescence-induced droplet jumping may be influenced by a variety of factors, such as droplet size [91,92], internal fluid dynamics [84], external vapor flow [93], substrate properties [94,95], substrate orientation [96], and electric fields [97,98]. Based on the coalescence of two quasi-stationary droplets of the same size on superhydrophobic rough surface, a relation among the jumping velocity, surface energy, viscous dissipation and droplet size whilst excluding the gravitational-potential energy was established as [92] 𝑣 = √ where Y was the function of apparent contact angle and fraction of the solid area wetted by liquid.…”

Section: Coalescence-induced Droplet Jumping and Direction Motion Of ...mentioning

confidence: 99%

“…The droplet jumping process is intrinsically inefficient because only a small portion of released excess surface energy (≤ 6%) can be converted into upward kinetic energy. Apart from the internal fluid dynamics, the external vapor flow can also mediate the droplet jumping and thus the heat transfer and pressure drop behavior inside a condenser tube [93]. The heat transfer coefficient was highest at lower surface subcooling and condensation heat flux.…”

Section: Coalescence-induced Droplet Jumping and Direction Motion Of ...mentioning

confidence: 99%

Condensation frosting and freezing of impact water droplets on cold surfaces

Zhu¹

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The accretion of ice/frost stemming from condensation frosting and freezing of impact water droplets is pervasive in both nature and industry, causing enormous losses every year worldwide especially in aviation and transportation. Most existing studies regarding condensation frosting focus on the anti-frosting potential by leveraging the ice-liquid or icevapor interactions on two-dimensional structured surfaces. Little is known about condensation frosting on one-dimensional surfaces with temperature gradient. This thesis first reports on the non-uniform condensate morphologies on a cantilevered microfiber during condensation due to the competition between conductive thermal resistance within the fiber and condensation heat transfer resistance on the fiber surface. Scaling analyses were provided to reveal the underlying physics. During the frosting phase, the nucleation of supercooled liquid microdroplet is triggered at locations where ice bridges are upon contact instead dropletsubstrate interfaces. Furthermore, an inter-droplet ice wicking regime is reported where the liquid droplet is sucked by physical contact of ice bridge, different from the classical interdroplet ice bridging. Such phenomenon results from the competition between wicking dynamics and nucleation crystallization timescales. Intriguingly, the frosting morphology on the microfiber demonstrates a similar trend to the condensate morphology. Moreover, the directional migration and easy assembling of melted water can be achieved by tailoring the fiber length and cooling temperature during defrosting, and well explained by the analytical models proposed. Additionally, a unique distribution pattern of condensed droplets is found during condensation on stainless-steel mesh, with one droplet atop every other knot. Such phenomenon arises from the extent of the region of inhibited condensation imposed by the central knot within the smallest periodic unit of the distribution pattern. Lattice Boltzmann simulation is implemented to obtain the water vapor concentration, and the pattern region under

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Jumping droplet condensation in internal convective vapor flow

Cited by 12 publications

References 32 publications

Advances in micro and nanoengineered surfaces for enhancing boiling and condensation heat transfer: a review

Advances in micro and nanoengineered surfaces for enhancing boiling and condensation heat transfer: a review

Visualizing and disrupting liquid films for filmwise flow condensation in horizontal minichannels

Condensation frosting and freezing of impact water droplets on cold surfaces

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