Geometry of the Vapor Layer Under a Leidenfrost Drop

Burton, Justin; Sharpe, Aaron; Veen, Roeland van der; Franco, Andres; Nagel, Sidney R.

doi:10.1103/physrevlett.109.074301

Cited by 181 publications

(188 citation statements)

References 21 publications

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“…This net upward force is applied to the projected area of the droplet and balances the weight of the droplet. As the droplet size is increased or decreased, both the droplet shape and the vapor layer thickness change as well [26], [27]. For large droplets, the shape of the droplet takes on a pancake profile while small droplets are more spherical.…”

Section: Resultsmentioning

confidence: 99%

Effects of droplet diameter on the Leidenfrost temperature of laser processed multiscale structured surfaces

Hassebrook

Kruse

Wilson

et al. 2014

Fourteenth Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)

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In this paper, an experimental investigation of the effects of droplet diameters on the Leidenfrost temperature and its shifts has been carried out. Tests were conducted on a 304 stainless steel polished surface and a stainless steel surface which was processed by a femtosecond laser to form Above Surface Growth (ASG) nano/microstructures. To determine the Leidenfrost temperatures, the droplet lifetime method was employed for both the polished and processed surfaces. A precision dropper was used to vary the size of droplets from 1.5 to 4 millimeters. The Leidenfrost temperature was shown to display shifts as high as 85 O C on the processed surface over the range of droplet sizes, as opposed to a 45 O C shift on the polished surface. The difference between the shifts was attributed to the nature of the force balance between dynamic pressure of droplets and vapor pressure of the insulating vapor layer.

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Section: Resultsmentioning

confidence: 99%

Effects of droplet diameter on the Leidenfrost temperature of laser processed multiscale structured surfaces

Hassebrook

Kruse

Wilson

et al. 2014

Fourteenth Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)

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“…Whereupon a liquid contacts with a surface significantly hotter than the liquid boiling point, gases formed between the liquid and the hotter surface produce an insulating layer which keeps that liquid from boiling rapidly; this phenomenon is known as Leidenfrost effect [26]. Due to the fact that the tungsten coil…”

Section: Heating Program Of Wcaesmentioning

confidence: 99%

Tungsten coil atomic emission spectrometry combined with dispersive liquid–liquid microextraction: A synergistic association for chromium determination in water samples

Vidal

Silva

Canals

et al. 2016

Talanta

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A novel and environmentally friendly analytical method is reported for total chromium determination and chromium speciation in water samples, whereby tungsten coil atomic emission spectrometry (WCAES) is combined with in situ ionic liquid formation dispersive liquid-liquid microextraction (in situ IL-DLLME).A two stage multivariate optimization approach has been developed employing a Plackett-Burman design for screening and selection of the significant factor involved in the in situ IL-DLLME procedure, which was later optimized by means were 3 and 10 µg L -1 , respectively. This is a 233-fold improvement when 2 compared with chromium determination by WCAES without using preconcentration. The repeatability of the proposed method was evaluated at two different spiking levels (10 and 50 µg L -1 ) obtaining coefficients of variation of 11.4 and 3.6% (n=3), respectively. A certified reference material (SRM-1643e NIST) was analysed in order to determine the accuracy of the method for total chromium determination and 112.3% and 2.5 µg L -1 were the recovery (trueness) and standard deviation values, respectively. Tap, bottled mineral and natural mineral waters were analysed at 60 µg L -1 spiking level of total Cr content at two Cr(VI)/Cr(III) ratios, and relative recovery values were ranged between 88 and 112% showing that the matrix has a negligible effect. To our knowledge, this is the first time that combines in situ IL-DLLME and WCAES.

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“…When theoretically deriving T L , one needs to determine the vapor thickness profile. In the case of a gently deposited droplet, this can be accomplished since the shape of the droplet is fixed except for the bottom surface, which reduces the problem to a lubrication flow of vapor in the gap between the substrate and the free surface [15][16][17][18][19][20]. For impacting droplets on an unheated surface at high Weber number We ≡ ρU 2 D 0 =σ (here, D 0 is the equivalent diameter of the droplet and ρ and σ are the density and the surface tension of the liquid, respectively), it is known that the neck around the dimple beneath the impacting droplet rams the surface.…”

mentioning

confidence: 99%

Dynamic Leidenfrost Effect: Relevant Time and Length Scales

et al. 2016

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When a liquid droplet impacts a hot solid surface, enough vapor may be generated under it to prevent its contact with the solid. The minimum solid temperature for this so-called Leidenfrost effect to occur is termed the Leidenfrost temperature, or the dynamic Leidenfrost temperature when the droplet velocity is non-negligible. We observe the wetting or drying and the levitation dynamics of the droplet impacting on an (isothermal) smooth sapphire surface using high-speed total internal reflection imaging, which enables us to observe the droplet base up to about 100 nm above the substrate surface. By this method we are able to reveal the processes responsible for the transitional regime between the fully wetting and the fully levitated droplet as the solid temperature increases, thus shedding light on the characteristic time and length scales setting the dynamic Leidenfrost temperature for droplet impact on an isothermal substrate. DOI: 10.1103/PhysRevLett.116.064501 Boiling and spreading of droplets impacting on hot substrates have been extensively studied since both phenomena strongly affect the heat transfer between the liquid and the solid. Applications include spray cooling [1], spray combustion [2], and others [3].At room temperature, an impacting droplet spreads on a solid surface and entraps a bubble under it [4][5][6]. At temperatures higher than the boiling temperature T b , vapor bubbles appear which disturb and finally rupture the free surface, resulting in the violent spattering of tiny droplets [7,8]. On even hotter surfaces, however, beyond the socalled Leidenfrost temperature T L , the droplet interface becomes smooth again without any bubbles inside it. In this regime the droplet lives much longer, as now it levitates on its own vapor layer: the well-known Leidenfrost effect [9,10].In order to determine the Leidenfrost temperature T L and its dependence on the impact velocity U, phase diagrams have been experimentally produced for various impacting droplets with many combinations of substrates and liquids: water on smooth silicon [8], water on microstructured silicon [11], FC-72 on carbon nanofiber [12], water on aluminium [13], and ethanol on sapphire [14]. All of these phase diagrams show a weakly increasing behavior of T L with U. When theoretically deriving T L , one needs to determine the vapor thickness profile. In the case of a gently deposited droplet, this can be accomplished since the shape of the droplet is fixed except for the bottom surface, which reduces the problem to a lubrication flow of vapor in the gap between the substrate and the free surface [15][16][17][18][19][20]. For impacting droplets on an unheated surface at high Weber number We ≡ ρU 2 D 0 =σ (here, D 0 is the equivalent diameter of the droplet and ρ and σ are the density and the surface tension of the liquid, respectively), it is known that the neck around the dimple beneath the impacting droplet rams the surface. In this cold impact case, the neck propagates outwards like a wave [21]. For impact on a superheated s...

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Geometry of the Vapor Layer Under a Leidenfrost Drop

Cited by 181 publications

References 21 publications

Effects of droplet diameter on the Leidenfrost temperature of laser processed multiscale structured surfaces

Effects of droplet diameter on the Leidenfrost temperature of laser processed multiscale structured surfaces

Tungsten coil atomic emission spectrometry combined with dispersive liquid–liquid microextraction: A synergistic association for chromium determination in water samples

Dynamic Leidenfrost Effect: Relevant Time and Length Scales

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