Navigation Links
Magnetic nanoparticles could aid heat dissipation

CAMBRIDGE, MA -- Cooling systems generally rely on water pumped through pipes to remove unwanted heat. Now, researchers at MIT and in Australia have found a way of enhancing heat transfer in such systems by using magnetic fields, a method that could prevent hotspots that can lead to system failures. The system could also be applied to cooling everything from electronic devices to advanced fusion reactors, they say.

The system, which relies on a slurry of tiny particles of magnetite, a form of iron oxide, is described in the International Journal of Heat and Mass Transfer, in a paper co-authored by MIT researchers Jacopo Buongiorno and Lin-Wen Hu, and four others.

Hu, associate director of MIT's Nuclear Reactor Laboratory, says the new results are the culmination of several years of research on nanofluids nanoparticles dissolved in water. The new work involved experiments where the magnetite nanofluid flowed through tubes and was manipulated by magnets placed on the outside of the tubes.

The magnets, Hu says, "attract the particles closer to the heated surface" of the tube, greatly enhancing the transfer of heat from the fluid, through the walls of the tube, and into the outside air. Without the magnets in place, the fluid behaves just like water, with no change in its cooling properties. But with the magnets, the heat transfer coefficient is higher, she says in the best case, about 300 percent better than with plain water. "We were very surprised" by the magnitude of the improvement, Hu says.

Conventional methods to increase heat transfer in cooling systems employ features such as fins and grooves on the surfaces of the pipes, increasing their surface area. That provides some improvement in heat transfer, Hu says, but not nearly as much as the magnetic particles. Also, fabrication of these features can be expensive.

The explanation for the improvement in the new system, Hu says, is that the magnetic field tends to cause the particles to clump together possibly forming a chainlike structure on the side of the tube closest to the magnet, disrupting the flow there, and increasing the local temperature gradient.

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 researchers say. "This is a basic study at the point," Buongiorno says. "It just shows this effect happens."


Contact: Sarah McDonnell
Massachusetts Institute of Technology

Related biology technology :

1. Controlling magnetic clouds in graphene
2. Spirax Sarco Releases the EFT10 Electromagnetic Flow Transmitter for Measurement of Conductive Fluids
3. Magnetic Resonance Imaging (MRI) System Market worth $5.24 Billion By 2018
4. New technology in the magnetic cooling of chips
5. Researchers invent acoustic-assisted magnetic information storage
6. UCLA engineers develop new energy-efficient computer memory using magnetic materials
7. New UCLA Engineering research center to revolutionize nanoscale electromagnetic devices
8. Magnetic vortex reveals key to spintronic speed limit
9. New phenomenon in nanodisk magnetic vortices
10. Tablet computers may interfere with settings on magnetically programmable shunt valves
11. International Survey of T2* Cardiovascular Magnetic Resonance in Thalassemia
Post Your Comments:
(Date:11/25/2015)... Studies reveal the differences in species of bacteria ... for more effective treatment for one of the most commonly ... --> --> Gum disease is one ... relatively little was understood about the bacteria associated with it ... researchers from the WALTHAM Centre for Pet Nutrition together with ...
(Date:11/25/2015)... , ... November 25, 2015 , ... ... the Organization of Black Aerospace Professionals (OPBAP) has been formalized with the signing ... AMA team leaders met with OPBAP leaders Capt. Karl Minter and Capt. Albert ...
(Date:11/24/2015)... Nov. 24, 2015  Asia-Pacific (APAC) holds the ... (CRO) market. The trend of outsourcing to low-cost ... but higher volume share for the region in ... however, margins in the CRO industry will improve. ... ( ), finds that the market ...
(Date:11/24/2015)... /CNW/ - iCo Therapeutics ("iCo" or "the Company") (TSX-V: ... the quarter ended September 30, 2015. Amounts, unless ... presented under International Financial Reporting Standards ("IFRS"). ... Andrew Rae , President & CEO of ... only value enriching for this clinical program, but ...
Breaking Biology Technology:
(Date:11/16/2015)... 2015  Synaptics Inc. (NASDAQ: SYNA ), ... announced expansion of its TDDI product portfolio with ... and display driver integration (TDDI) solutions designed to ... TDDI products add to the previously-announced TD4300 ... resolution), and TD4322 (FHD resolution) solutions. All four ...
(Date:11/10/2015)... 10, 2015  In this report, the ... of product, type, application, disease indication, and ... report are consumables, services, software. The type ... biomarkers, efficacy biomarkers, and validation biomarkers. The ... diagnostics development, drug discovery and development, personalized ...
(Date:11/2/2015)... Nov. 2, 2015  SRI International has been awarded ... preclinical development services to the National Cancer Institute (NCI) ... provide scientific expertise, modern testing and support facilities, and ... pharmacology and toxicology studies to evaluate potential cancer prevention ... The PREVENT Cancer Drug Development Program is an NCI-supported ...
Breaking Biology News(10 mins):