US physicists made ice levitate over heated metal
Miscellaneous / / January 25, 2022
This effect will help cool equipment - from computers to nuclear power plants.
If a drop of water hits a surface that is much hotter than the boiling point of that liquid, it will levitate above it. This effect is named after the German physician and theologian Johann Gottlob Leidenfrost, who first described it in 1756.Boiling and the Leidenfrost effect.
In a new study, Virginia Tech Associate Professor of Mechanical Engineering Jonathan Boreyko and his graduate student Mojtaba Edalatpour achieved Using ice to boil water: Researcher makes heat transfer discovery that expands on 18th century principle levitation of a piece of ice. In fact, they experimentally proved a theory first voiced in the 18th century.
The scientists explained: if you bring an aluminum plate to 150 ° C, then a pillow of steam forms under it. It separates the water from the metal - and the drop will levitate or glide across the surface like an air hockey puck.
If, under the same conditions, a piece of ice is placed on an aluminum plate, it will gradually melt and turn into water. Melt water will boil, but steam will not form under it.
But when the scientists heated the plate to 550°C, the Leidenfrost effect appeared and for ice. Due to the steam, the ice rose above the surface, although it continued to melt.
This behavior is explained by the temperature difference in the layer of melt water. At the bottom it boils at 100°C, at the top it melts at 0°C. If the heating is very high, a vapor cushion has time to form between the heated plate and the ice.
The results of the study will allow the creation of new cooling systems for cars, servers and even nuclear power plants. The effect will help to find substances or mechanisms that can quickly remove or redistribute heat, reducing equipment wear and preventing dangerous situations.
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