While the idea has been suggested before, it had never been proved in action, Hu says. "This is the first work we know of that demonstrates this experimentally," she says.
Such a system would be impractical for application to an entire cooling system, she says, but could be useful in any system where hotspots appear on the surface of cooling pipes. One way to deal with that would be to put in a magnetic fluid, and magnets outside the pipe next to the hotspot, to enhance heat transfer at that spot.
"It's a neat way to enhance heat transfer," says Buongiorno, an associate professor of nuclear science and engineering at MIT. "You can imagine magnets put at strategic locations," and if those are electromagnets that can be switched on and off, "when you want to turn the cooling up, you turn up the magnets, and get a very localized cooling there."
While heat transfer can be enhanced in other ways, such as by simply pumping the cooling fluid through the system faster, such methods use more energy and increase the pressure drop in the system, which may not be desirable in some situations.
There could be numerous applications for such a system, Buongiorno says: "You can think of other systems that require not necessarily systemwide cooling, but localized cooling." For example, microchips and other electronic systems may have areas that are subject to strong heating. New devices such as "lab on a chip" microsystems could also benefit from such selective cooling, he says.
Going forward, Buongiorno says, this approach might even be useful for fusion reactors, where there can be "localized hotspots where the heat flux is much higher than the average."
But these applications remain well in the future, the research
|Contact: Sarah McDonnell|
Massachusetts Institute of Technology