Milestone in Magnetic Cooling
September 5th, 2007Danish researchers are developing a silent, very low power refrigeration technology that uses magnets.
Via: Physorg:
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 “orderâ€, 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.
Fascinating. There is more potential here methinks than simply refridgeration. One thing that comes to mind is that magnets themselves (at least some of them) are stronger when cooler and weaker when hotter. I am thinking that something might be done with this and incorporating perhaps the sun for heat on one end and maybe a deep shaft underground on the other end… resulting in a magnet being lifted by both magnetic pull at the top and push from the bottem and then after reaching the top heating up and losing magnetic strength, then falling (via gravity), only to cool again (via both being underground and this new cooling method), regain its strength and rise on magnetic force… passing through a coil both ways of course. Free energy anyone? Am I rambling? 😉