Heat transport for evaporating droplets on superhydrophilic, thin, nanoporous layers

Wemp, Claire K.; Carey, Van P.

doi:10.1016/j.ijheatmasstransfer.2018.11.143

Cited by 18 publications

(4 citation statements)

References 24 publications

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“…The micro/nanostructured surface with superior wicking capability has been shown to promote evaporation and boiling heat transfer, delay the occurrence of dry out, and enhance the critical heat flux. The above enhancements are attributed to the capillary wicking identified as the mechanism to keep the surface wetted at high superheat and to rewet the dry spots, preventing the burn out. − …”

Section: Introductionmentioning

confidence: 99%

Fast Capillary Wicking on Hierarchical Copper Nanowired Surfaces with Interconnected V-Grooves: Implications for Thermal Management

Jiang

Chen

Zhang

et al. 2021

ACS Appl. Nano Mater.

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Evaporation and boiling heat transfer on micro/nanostructured surfaces with superior wicking capability is an efficient cooling approach for high heat flux removal. The enhancement of the wicking capability has been identified as a key mechanism to enhance heat transfer efficiency and prevent thermal crisis. However, the capillary wicking capability is limited by the trade-off between the capillary pressure and the viscous resistance on the length scale of the structure feature. Here, we report a rapid capillary wicking capability on hierarchical nanowired surfaces with interconnected V-grooves, whose wicking coefficient reaches 6.54 mm/s0.5. This is attributed to the highly uniform copper nanowires which provide prominent capillary pressure while the interconnected V-grooves provide liquid film transport channels to reduce the viscous resistance. We experimentally investigated the effect of nanowire spacing, V-groove fraction, and V-groove depth on the wicking coefficient for various liquids with surface tension to viscosity ratios from 6 to 81. Larger fractions and depths of such V-grooves lead to higher wicking coefficients. Moreover, the wicking coefficient is increased as the surface tension to viscosity ratio of the liquid increases. This work offers guidelines for designing and optimizing hierarchical structures to enable ultrafast liquid film wicking, thus highlighting the thermal management potential.

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Section: Introductionmentioning

confidence: 99%

Fast Capillary Wicking on Hierarchical Copper Nanowired Surfaces with Interconnected V-Grooves: Implications for Thermal Management

Jiang

Chen

Zhang

et al. 2021

ACS Appl. Nano Mater.

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“…Challenges arise due to the dynamic and transient nature of interaction between the thin-film menisci present within the structures with the continuously changing droplet’s interfacial curvature as well as decreasing droplet volume. Consequently, wicking experiments to study droplet evaporation dynamics on heated structured surfaces at temperatures below nucleation have been sparsely conducted, ,− as structures are open to the environment resulting in small wicking distances. In order to optimize structure/liquid supply design and maximize heat flux removal, estimations of heat flux in micro/nanostructures as well as at the surface, along with dryout limits, are important.…”

Section: Introductionmentioning

confidence: 99%

Droplet Evaporation on Porous Nanochannels for High Heat Flux Dissipation

Poudel

Zou

Maroo

2020

ACS Appl. Mater. Interfaces

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Droplet wicking and evaporation in porous nanochannels is experimentally studied on a heated surface at temperatures ranging from 35 o C to 90 o C. The fabricated geometry consists of cross-connected nanochannels of height 728 nm with micropores of diameter 2 µm present at every channel intersection; the pores allow water from a droplet placed on the top surface to wick into the channels. Droplet volume is also varied and a total of 16 experimental cases are conducted. Wicking characteristics such as wicked distance, capillary pressure, viscous resistance and propagation coefficient are obtained at the high surface temperatures. Evaporation flux from the nanochannels/micropores is estimated from the droplet experiments, but is also independent confirmed via a new set of experiments where water is continuously fed to the sample through a microtube such that it matches the evaporation rate. High heat flux as high as ~294 W/cm 2 is achieved from channels and pores. The experimental findings are applied to evaluate the use of porous nanochannels geometry in spray cooling application, and is found to be capable of dissipating high heat fluxes upto ~77 W/cm 2 at temperatures below nucleation, thus highlighting the thermal management potential of fabricated geometry.

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“…Such surfaces have attracted attention, due to their many applications, including anti-fogging [11], bio-fouling prevention [12], biomedicine [13-17] and self-cleaning [18-21] capabilities. Additional applications, in practical environments that involve dynamic water impact on such surfaces, have persuaded us to give attention to the dynamic behaviours of water droplets on these surfaces, which, although not necessarily suited to heat transport [22-24], may be important in applications such as spraying, ink-jet printing [25], pharmaceuticals [26], aircraft deicing [27,28], microfluidic devices, droplet manipulation, cell screening and water harvesting through superhydrophilic–superhydrophobic patterned surfaces [29] or switching [30].…”

Section: Introductionmentioning

confidence: 99%

Dynamic behaviours and drying processes of water droplets impacting on superhydrophilic surfaces

Zhu

Liu

et al. 2021

Surface Engineering

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The dynamic water contact performances and drying processes of two commercially available superhydrophilic coatings, QS200, used for glass antifogging, and QS3100, used for the selfcleaning of solar photovoltage panels, both with static contact angles near zero, have been evaluated. We investigated the drying behaviours of both statically and dynamically deposited water droplets on these two coatings by measuring droplet diameters and mass changes, and found that their dynamic water droplet behaviours were substantially different, although their static contact angles were essentially the same. The dynamic behaviour of water droplet impact on the QS200 coating was basically independent on the water droplet height (impact speed), while that on the QS3100 coating changed with droplet height. The drying times of droplets on the QS200 coating, both statically and dynamically deposited, were longer than on the QS3100 coating, although the initial droplet area on the QS200 coated surface was larger.

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Heat transport for evaporating droplets on superhydrophilic, thin, nanoporous layers

Cited by 18 publications

References 24 publications

Fast Capillary Wicking on Hierarchical Copper Nanowired Surfaces with Interconnected V-Grooves: Implications for Thermal Management

Fast Capillary Wicking on Hierarchical Copper Nanowired Surfaces with Interconnected V-Grooves: Implications for Thermal Management

Droplet Evaporation on Porous Nanochannels for High Heat Flux Dissipation

Dynamic behaviours and drying processes of water droplets impacting on superhydrophilic surfaces

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