Inverse-Leidenfrost phenomenon on nanofiber mats on hot surfaces

Abstract

The Leidenfrost effect is a technically and industrially important phenomenon that severely restricts heat removal from high-heat-flux surfaces. A simple remedy to the Leidenfrost effect is provided by polymer nanofiber mats created and deposited by electrospinning on stainless steel surfaces. The influence of nanofiber mats on hydrodynamics and cooling efficiency of single drop impact onto hot surfaces has been investigated experimentally. The evolution of the drops has been recorded by a high-speed complimentary metal-oxide semiconductor camera, whereas the cooling temperature was measured by a thermocouple. A remarkable phenomenon was discovered: a mat of polymer nanofibers electrospun onto a heater surface can completely suppress the Leidenfrost effect, thereby increasing the rate of heat removal from the surface to the liquid drops significantly. The "inverse-Leidenfrost" effect is described qualitatively and quantitatively, providing clear physical reasons for the observed behavior.

Propulsion on a superhydrophobic ratchet

“…It is known that Leidenfrost temperature can be modulated by textures at the solid surface1011. Fibrous microstructures, for example, largely increase T L 12; conversely, superhydrophobic textures considerably lower the Leidenfrost temperature, as recently reported by Vakarelski et al 13 and del Cerro et al 14 . On such materials, the transition between non-wetting and Leidenfrost states becomes continuous, owing to the repellent nature of the texture.…”

Effect of fiber orientation on shape and stability of air–water interface on submerged superhydrophobic electrospun thin coatings

“…(9), and considering the fact that dF 0 (because the interface moves downward as the hydrostatic pressure increases), we get, ð…”

“…Under dynamic penetration regimes, e.g., droplet impact on a superhydrophobic surface, the transition from Cassie state may occur at a much lower pressure. [7][8][9] Balance of forces has been used to investigate the shape and stability of the air-water interface on superhydrophobic surfaces with ordered microstructures. 4,6,[10][11][12][13][14][15][16] Our group has recently used balance of forces to calculate the shape and stability of the air-water interface on superhydrophobic surfaces with randomly distributed posts of dissimilar sizes, heights, and materials 17 as well as elliptical and polygonal shallow pores.…”

Droplet impact behavior on heated micro-patterned surfaces

“…Towards this end, various strategies have been adopted, including modifying the substrate surface, changing the surface tension of the liquid as well as the manner of droplet deposition, or applying an electric field between the droplet and the heated surface. 12 Some studies claim that surface roughness is an important feature that can lead to an increase in Leidenfrost temperature, [13][14][15][16] while others show a reversed trend. 17,18 In recent years, micropatterned surfaces have also drawn much attention.…”