This phenomenon is most commonly seen when cooking, drop in a pot of water where the temperature is well above the boiling point of water or above the Leidenfrost point, the water droplets will roll pan and takes longer to evaporate than in the pot temperature below the Leidenfrost point ( but still above the boiling point).
This effect also explains why our hands are fine although liquid nitrogen is poured. Nitrogen has a boiling point of -196 ° C, and the temperature of the human body is about 37 ° C, is very hot for nitrogen.
Then, when the meeting of liquid nitrogen by hand, Leidenfrost effect ensued. Liquid nitrogen will be retained by the steam itself, this causes the liquid nitrogen droplets away from the surface of the skin.
However, this will not happen forever, when we are too old to pour liquid nitrogen into our hands, the hands will cause the liquid nitrogen cooled and does not evaporate as fast as before.
So, when a drop of water touches the hot surface (slightly above the boiling point), the water drops quickly evaporated.
But if the water droplet was dropped / touch surface is very hot (well above the boiling point), only a few of the outer layer of the droplets are evaporated, resulting in the isolation effect that causes residual droplets on the surface of the hot rolling.
Well, when the water droplets hit the surface very hot but refined, they tend to roll or jump to a random direction. But researchers have found that if the surface has a very hot ridged texture, droplets move only in one direction only.
Two university students from Bath, Carmen Cheng and Matthew Guy, to build a maze of jagged aluminum surface is then heated above the Leidenfrost point of water.
When droplets of water dropped on the maze, it looks as if the water droplets can traverse the halls complex maze itself. Look at the video below:
Source :
apakabardunia
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