Magnetic fields could super-cool your gaming PC, nuclear reactors

As any good chef knows, mechanical stress aids the transfer of thermodynamic energy in a closed system. They employ this knowledge every time they press an ingredient down into a pan or grill, greatly increasing the efficiency of heat transfer from metal to food. We usually see that interaction exclusively from one perspective, that of using the pan to add heat to the food. But it would be just as accurate to say that we are using the food to remove heat from the pan — and by pressing it down we assist it in “cooling” the metal. Now a team of researchers are using this fundamental fact, along with a strong magnetic field and a flood of metal nanoparticles, to make liquid cooling systems many times more effective.

The basic premise is fairly simple: if you flood a coolant with a slurry of magnetic nanoparticles, then subject that suspension to a magnetic field, the nanoparticles can help affect the flow of the whole fluid, helping to make cooling more effective. It’s a basic enough idea that it can scale to virtually any size for an applicable type of cooling rig. Anything cooled by a liquid is an immediate candidate — and to continue advancing at such a pace, more and more of our technology will require a heat-sink fluid more efficient than air.

A sample of magnetite, the material used to make the magnetic nanoparticles.

Creating the magnetic field will get much more expensive at larger scales however, and this tech could be suited to miniaturization by decreasing the volume of liquid necessary to cool a particular heat source. These nanoparticles are made of magnetite, though, the most powerfully magnetic of all naturally occurring minerals; they do provide enough magnetic grip even for large jobs like cooling nuclear reactors.

The nanoparticles are attracted closer the to the heated surface of the tube and make chainlike structures on the side closest to the magnet. This effectively makes the pipes “rough” at certain spots and assists cooling by increasing the momentum of particles in the fluid, and thus energy transfer upon collisions. It’s not exactly like pressing toast into a pan, but the nanoparticle aggregates can disrupt coolant flow, increasing the local temperature gradient and causing the coolant to soak up more energy. This all basically boils down to increasing the number of collisions between molecules, helping to keep the coolant in close contact with the heated pipes. The nuclear industry is generally tending toward “passive” cooling technologies though, ones that work even without power; an actively maintained magnetic field may prove something of a hard sell, even if it is proven effective.

The experimental setup.

One limitation of the technology is that the pressure it exerts is mostly useful for cooling small hotspots in a larger system — it can’t do its work over an entire elaborate network of coolant pipes. Nuclear reactors and computers both have strong heat producers in and amongst relatively cool components. System-on-a-chip setups are even better suited to this idea, as it allows the cooling system to make the best use of the short periods of contact between coolant and their pinpoint heat sources. It will admittedly be quite a while before the average gaming PC needs anything approaching this level of heat capacity to run a bleeding edge game engine, but many servers and other work-horse machines already look to liquid for better cooling capacity.

This is the first practical demonstration of an effect that’s been in discussion for some time. One big advantage is that it could plausibly be used to augment existing coolant systems with the addition of strategically placed electromagnets and a shot of magnetite nanoparticles. The researchers even suggest it could be used to help make fusion reactorsa reality. Being built on such a simple insight, this is one discovery that could be paying dividends in a wide variety of areas going forward.

Now read: MIT discovers a new state of matter, a new kind of magnetism