Sunday, September 16, 2012

Boiling without bubbles?

There was a bit of a flurry of articles, notes, Facebook shares and the like this week surrounding a new application of the Leidenfrost effect. We loves us some Leidenfrost effect here at The Blog of Phyz, so a post is required.

When a very hot metal ball is placed in near-boiling water, an enveloping layer of water vapor surrounds the ball. This insulates the ball, preventing it from cooling down by conduction to the cooler water. The heat transfer is relatively slow. Bubbles peel off from the submerged ball (single file) while the ball cools. Eventually, the ball cools to a point at which it can no longer maintain its vapor "atmosphere."

The new research shows that if the metal ball is coated with nanoparticles, the bubble production from the submerged ball eventually drops to zero.

Here's the video from researchers at Northwestern.

Boiling Water Without Bubbles from Northwestern News on Vimeo.

Full articles are here:
Nature: Stabilization of Leidenfrost vapour layer by textured superhydrophobic surfaces

Scientific American: How to Boil Water without Bubbles

Northwestern: Boiling Water Without Bubbles

Popularizers did their best to popularize this mildly esoteric finding.
New Scientist: Water-repellent balls make liquid boil with no bubbles

Geekosystem seems to have taken things too far.

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