Boiling Heat Transfer Performance in a Spiraling Radial Inflow Microchannel Cold Plate

Ruiz, Maritza; Kunkle, Claire M.; Padilla, Jorge; Carey, Van P.

doi:10.1080/01457632.2016.1242954

Cited by 7 publications

(6 citation statements)

References 13 publications

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“…The nanostructure surface features listed above are of central interest here because they were characteristics observed experimentally for superhydrophilic ZnO nanostructured surfaces studied by Ruiz et al . and Padilla and Carey, and they are expected to be representative of the behavior for other similar superhydrophilic nanostructured surfaces.…”

Section: Model Formulationmentioning

confidence: 85%

Water Wicking and Droplet Spreading on Randomly Structured Thin Nanoporous Layers

Wemp

Carey

2017

Langmuir

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Growing thin, nanostructured layers on metallic surfaces is an attractive, new approach to create superhydrophilic coatings on heat exchangers that enhance spray cooling heat transfer. This paper presents results of an experimental study of enhanced droplet spreading on zinc oxide, nanostructured surfaces of this type that were thermally grown on copper substrates. The spreading rate data obtained from experimental high speed videos was used to develop a model specifically for this type of ultrathin, nanoporous layer. This investigation differs from previous related studies of droplet spreading on porous surfaces, which have generally considered either ordered, thin, moderately permeable layers, or thicker, microporous layers. Our layers are both very thin and have nanoscale porosity, making them low-permeability layers that exhibit strong wicking. An added benefit is that the thermally grown, stochastic nature of our surfaces make manufacturing easily scalable and particularly attractive for spray-cooled heat exchanger applications. The model presented here can predict the spreading rate for the wetted footprint of a deposited water droplet over two spreading stages: an early synchronous spreading stage, followed by hemispreading. The comparison of experimental data and model predictions confirms the presence of these two specific spreading stages. The model defines the transition conditions between synchronous and hemispreading regimes based on the change in spreading mechanisms, and we demonstrate that the model predictions of spreading rate are in good agreement with the experimental determinations of droplet footprint variation with time. The results indicate that the early synchronous spreading regime is characterized by flow in the porous layer that is primarily localized near the upper droplet contact line. The potential use of these experimental findings and model for optimizing superhydrophilic, nanostructured surface coatings is also discussed, as it pertains to the surface's ability to enhance water vaporization processes.

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Section: Model Formulationmentioning

confidence: 85%

Water Wicking and Droplet Spreading on Randomly Structured Thin Nanoporous Layers

Wemp

Carey

2017

Langmuir

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“…It can be seen that, as the decreasing contact angle, the bubble separation frequency is increased, whereas the bubble separation diameter is decreased. This phenomenon has been demonstrated by a great deal of visualization experiments (Ruiz et al 2017;Yim et al 2019), which can be seen in Fig. 3.…”

Section: Bubble Dynamics On the Homogeneous Wetting Surfacementioning

confidence: 73%

Recent Advances of Surface Wettability Effect on Flow Boiling Heat Transfer Performance

Cao¹,

Yang²,

Zhao³

et al. 2022

Frontiers in Heat and Mass Transfer

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“…The nanostructure surface features listed above are of central interest here because they were characteristics observed experimentally for superhydrophilic ZnO nanostructured surfaces studied by Ruiz et al [17] and Padilla and Carey [18], and they are expected to be representative of the behavior for other similar superhydrophilic nanostructured surfaces. Previous studies of droplet spread on surfaces mentioned above have not considered this specific type of surface (e.g., see Refs.…”

Section: Model Formulationmentioning

confidence: 82%

“…and since the rate of mass delivery to r ¼ R must equal the mass growth rate of the liquid in the nanostructured layer as specified from the conservation of mass relation (17), equating the right sides of Eqs. (30) and (17) yields…”

Section: Model Formulationmentioning

confidence: 99%

“…Numerous recent investigations have examined the use of nanostructured surfaces to enhance features of water boiling or liquid water evaporation processes. Since prior research has shown that increasing surface wetting by the liquid generally improves boiling performance, it is not surprising that use of nanostructured hydrophilic surfaces has frequently been proposed as a means of enhancing nucleate boiling heat transfer and critical heat flux (CHF) for pool boiling [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16], suppressing wall dryout in flow boiling [17], and enhancing droplet spread and evaporation heat transfer in water spray cooling [18,19]. The use of superhydrophilic nanostructured surfaces would appear to offer the promise that substantial enhancement of water pool boiling and liquid evaporation processes, since superhydrophilic surface structures of this type have been found to exhibit rapid spreading of liquid over an initially dry surface [7,8,18].…”

Section: Introductionmentioning

confidence: 99%

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Tuning Superhydrophilic Nanostructured Surfaces to Maximize Water Droplet Evaporation Heat Transfer Performance

Wemp

Carey

2018

Journal of Heat Transfer

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Spraying water droplets on air fin surfaces is often used to augment the performance of air-cooled Rankine power plant condensers and wet cooling tower heat exchangers for building air-conditioning systems. To get the best performance in such processes, the water droplets delivered to the surface should spread rapidly into an extensive, thin film and evaporate with no liquid leaving the surface due to recoil or splashing. This paper presents predictions of theoretical/computational modeling and results of experimental studies of droplet spreading on thin-layer, nanostructured, superhydrophilic surfaces that exhibit very high wicking rates (wickability) in the porous layer. Analysis of the experimental data in the model framework illuminates the key aspects of the physics of the droplet-spreading process and evaporation heat transfer. This analysis also predicts the dependence of droplet-spreading characteristics on the nanoporous surface morphology and other system parameters. The combined results of this investigation indicate specific key strategies for design and fabrication of surface coatings that will maximize the heat transfer performance for droplet evaporation on heat exchanger surfaces. The implications regarding wickability effects on pool boiling processes are also discussed.

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Boiling Heat Transfer Performance in a Spiraling Radial Inflow Microchannel Cold Plate

Cited by 7 publications

References 13 publications

Water Wicking and Droplet Spreading on Randomly Structured Thin Nanoporous Layers

Water Wicking and Droplet Spreading on Randomly Structured Thin Nanoporous Layers

Recent Advances of Surface Wettability Effect on Flow Boiling Heat Transfer Performance

Tuning Superhydrophilic Nanostructured Surfaces to Maximize Water Droplet Evaporation Heat Transfer Performance

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