July 4, 2008

RPI’s Nano Research Heating Up: A Quicker Boiling Pot of Water Could Lead to Much Bigger Things in Small Science

By Larry Rulison, Albany Times Union, N.Y.

Jul. 4--TROY -- An associate professor at Rensselaer Polytechnic Institute has figured out a way to make a pot of water boil more quickly.

Nikhil Koratkar and a team of researchers at RPI lined a pot with tiny copper nanorods. They found that the copper material more effectively induced the "phase change" that occurs when the pot is heated to the boiling point, turning the water to vapor.

The resulting benefit is that less energy is required to do more work -- in this case boil water.

"If you need less energy to boil water, then that is something that can be very useful," Koratkar said Thursday.

Koratkar and his team published a paper on their discovery in the June issue of the journal Small.

The copper nanorods help facilitate the boiling process. The bottom of a pot has tiny microcavities where air gets trapped, and water boils when vapor pressure forces these air bubbles to the surface of the water in a process called nucleation.

Typically, when the air bubbles leave these microcavities, they fill with water, preventing further nucleation from that specific cavity.

When placed on the bottom of a copper pot, copper nanorods feed nanobubbles of air into these microcavities, thereby preventing them from filling entirely with water.

As a result, the boiling pot will be able to create 30 times more bubbles and 10 times more vapor, meaning the pot becomes that more efficient at boiling.

Koratkar said the copper nanorods may one day be used for more significant breakthroughs in areas such as cooling computer chips.

As chips are made smaller and smaller, it becomes increasingly more difficult to control heat in what are known as "hotspots."

Koratkar said boiling can be used as a heat-transfer mechanism to cool chips, and the copper nanorods could be easily deposited on to the copper interconnects on chips, making them easier to cool. That research has yet to take place.

Copper nanorods are different from carbon nanotubes, which also have been used in nanotechnology research recently. Unlike carbon nanotubes, copper nanorods are solid. And they are larger. While carbon nanotubes may be about 10 nanometers wide, copper nanorods are five to 10 times larger.

Nanoscale materials are the smallest made by man. A nanometer is one-billionth of a meter. A strand of hair is about 80,000 nanometers wide.

Although Koratkar believes his copper nanorod discovery could have a lot of commercial applications -- he could also see them used in other heat-transfer technologies and for industrial boiling -- he said he hasn't been been able to verify how robust the material is, or how long, for instance, it would stay on a pot.

"There are still issues that need to be looked at," he said. "Do they age over time? If you really want to make a product, these questions are important."

Koratkar said he already has received phone calls from companies wanting to know more about his discovery, and he's hoping that will lead to more funding to learn more about the material and commercial applications. He said RPI also is looking into filing a patent for the research in hopes the university would one day license the technology.

"The reason we're getting so many phone calls is because this is related to energy," he said. Rulison can be reached at 454-5504 or by e-mail at [email protected]


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