Milestone in magnetic cooling

August 24, 2007

The first milestone in magnetic cooling has been achieved. Between 5 and 10 degrees of cooling – this was the success criteria for the first milestone in a project involving magnetic cooling at Risø National Laboratory – Technical University of Denmark (DTU).

And the figure is currently at 8.7°C – this means that a refrigerator at room temperature (20°C) can be cooled to almost 11°C. Of course, this is not quite enough to keep the milk cold, but the project’s test setup also has only the one objective of conducting research in different materials, varying operating conditions and the strength of the magnetic field.

“The setup is not the largest of its type, but the most important thing is that it ’s easy to exchange parts in the machine. With the knowledge that we gain along the way, we will ultimately be able to build the very best magnetic cooling system,” explains Christian Bahl, a postdoctoral student attached to the project for one year.

How is a magnetic field used for cooling?

Magnetic cooling technology exploits the fact that when a magnetic material, in this case the element gadolinium, is magnetised, heat is produced as a by-product of entropy. The principle of entropy is that there will always be a constant amount of order/disorder in a substance. When the magnet puts the substance in “order”, it has to get rid of the excess disorder – and this becomes heat. Conversely, when the magnetic field is again removed, the substance becomes cold.

The heat is transferred to a fluid that is pumped back and forth past the substance inside a cylinder. The end that becomes cold will be located inside the refrigerator and the warm end will be outside.

Why magnetic cooling?

It is natural to wonder: Why magnetic cooling? After all, there are decent and also relatively energy-efficient refrigerators on the market. But there are three good reasons why this type of cooling has a future.

First, the technology is potentially more energy-efficient than the alternatives. It only really uses energy to move the magnetic field to and from the magnetic material. The model currently under development produces the magnetic field through a system of powerful blocks of magnets similar to those we use on our refrigerator doors, only stronger. These do not get worn out, and thus do not need replacing, which is very good for the environment.

This leads to the second major benefit, namely the fluid, which could turn out to be just plain water. Consequently, there would not be the same environmental impact as with today’s compressor-based refrigerators. The third great potential difference is the noise level. Bahl expects their demonstration model, which should be ready in 2010, to be practically silent. The opportunities are obvious.

“It is probably not realistic to think that magnetic cooling technology will be used in consumers’ homes right away. Manufacturers have spent too many years streamlining the prices of the existing refrigerators. Initially, it will be about implementation in various types of niche applications – large-scale refrigerating plants, soda machines or places where a noise-free environment is important,” says Bahl, adding, however, that he believes it will ultimately spread to the rest of society.

On a global scale, there are at least ten other teams working on similar projects involving magnetic cooling, but the field has not yet become a major focus area. The concept of magnetic cooling has been known for many years, but using the technology at room temperature is something relatively new.

At Risø’s Department of Fuel Cells and Solid State Chemistry, Senior Scientist Nini Pryds has received a grant of approximately DKK* 14 million from the Danish Council for Strategic Research Programme Commission on Energy and Environment. Along with the DKK 7 million that Risø and the three partners – DTU’s Department of Manufacturing and Engineering Management, Sintex and Danfoss – are investing in the MagCool project, it will be possible to develop a prototype.

Sintex has the expertise in permanent magnetic fields, and the company is currently developing the model of magnets that will produce the powerful magnetic field for Risø’s test model. Another objective of the project is to determine whether this technology can pave the way for the super-efficient and environmentally friendly refrigeration machine of the future.

*1 Danish krone = 0.182 U.S. dollars

Source: RISO

Explore further: Earth not due for a geomagnetic flip in the near future, researchers show

Related Stories

Cool, dim dwarf star is magnetic powerhouse

November 19, 2015

Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have discovered that a dim, cool dwarf star is generating a surprisingly powerful magnetic field, one that rivals the most intense magnetic regions ...

New metal alloy could yield green cooling technologies

October 30, 2015

A promising new metal alloy system could lead to commercially viable magnetic refrigerants and environmentally friendly cooling technologies, according to a scientist at Rochester Institute of Technology.

What's it like to see auroras on other planets?

November 10, 2015

Witnessing an aurora first-hand is a truly awe-inspiring experience. The natural beauty of the northern or southern lights captures the public imagination unlike any other aspect of space weather. But auroras aren't unique ...

Rubidium atoms used as a refrigerant for ytterbium atoms

November 12, 2015

For many years rubidium has been a workhorse in the investigation of ultracold atoms.  Now JQI scientists are using Rb to cool another species, ytterbium, an element prized for its possible use in advanced optical clocks ...

Recommended for you

Turbulence in bacterial cultures

November 30, 2015

Turbulent flows surround us, from complex cloud formations to rapidly flowing rivers. Populations of motile bacteria in liquid media can also exhibit patterns of collective motion that resemble turbulent flows, provided the ...

Test racetrack dipole magnet produces record 16 tesla field

November 30, 2015

A new world record has been broken by the CERN magnet group when their racetrack test magnet produced a 16.2 tesla (16.2T) peak field – nearly twice that produced by the current LHC dipoles and the highest ever for a dipole ...

CERN collides heavy nuclei at new record high energy

November 25, 2015

The world's most powerful accelerator, the 27 km long Large Hadron Collider (LHC) operating at CERN in Geneva established collisions between lead nuclei, this morning, at the highest energies ever. The LHC has been colliding ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.