Scientists Control the Bubbles of Boiling Water

Posted on November 1, 2015

MIT researchers say they have found a way to control the bubbles of boiling water. Boiling water is central to desalination plants and to most electric power plants, heating and cooling systems. The researchers say they can control the boiling bubbles with the flick of an electrical switch.

The new feat was accomplished by adding surfactants (also known as detergents) to water which essentially creates a soapy liquid. The surfactant molecules carry an electrical charge. The molecules can be attracted to, or repelled by, a metal surface by changing the polarity of the voltage applied to the metal. Department of Mechanical Engineering Professor Evelyn Wang says this switches the metal surface between being hydrophilic and hydrophobic.

Adding more surfactant causes the surface to become more hydrophobic, which increases the rate of nucleation to form bubbles. Reversing the charge on the surface causes the surface causes the surface to become hydrophilic, and inhibits the formation of bubbles. The researchers were able to achieve a tenfold rate in the bubble formation using this technique.

Being able to control the bubble formation rate makes it possible to control the rate of heat transfer between the metal and the liquid. The researchers say this could lead to more efficient boilers for power plants. MIT graduate student Jeremy Cho says the system, "provides the ability to pick the best heat-transfer profile on an as-needed basis. This allows you to pick the optimum rate of heat transfer moment by moment."

A research paper on the control over the boiling bubbles was published here in the journal, Nature Communications.

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