Hardware 2.0

Adrian Kingsley-Hughes

Apple's obsession with magnets could mean better cooling for your next Mac

By Adrian Kingsley-Hughes | January 28, 2012, 4:12am PST

Summary: Ferrofluids + magnets = awesome cooling solution

Magnets … just how do they work? Well, one company that seems to have a very good grasp on how magnets work is Apple, and the Cupertino giant is busy patenting technology that makes use of their odd properties.

I’m not usually a big fan of trawling through patents because companies tend to patent all kinds of weird and wonderful stuff, and most of the time it’s done just to keep other from using the technology, but a patent uncovered the Patently Apple on magnet technology makes very interesting reading indeed. One bit in particular caught my eye, related to using ferrofluid for cooling:

Another twist relating to thermal management is presented in Apple’s patent that deals with the use of correlated magnets in conjunction with a ferrofluid for a cooling system. According to Apple, as a ferrofluid is heated, its magnetic qualities decrease (e.g., it becomes less attracted to a magnet). Thus, a magnet near an element to be cooled will attract ferrofluid which will be heated by the element, thereby becoming less magnetically sensitive. The heated ferrofluid will flow away from the magnet and be replaced by cool ferrofluid. This cycle may continue indefinitely.

To me this is one of those ‘why hasn’t someone already thought of this?’ ideas. It’s absolutely brilliant. A magnet acts as a pump (a pump with no moving parts whatsoever, and needs no power or maintenence), and the ferrofluid acts as the coolant. Cool ferrofluid is drawn to the part that requires cooling and then as that ferrofluid warms up and becomes less magnetic, fresh cool ferrofluid replaces it.

Brilliant!

This devices solves so many problems associated with cooling electronics devices:

A system like this would be small and self-contained.
It requires no power.
No maintenance system.
Sealed system, no risk of leaks (you definitely wouldn’t want ferrofluid leaking inside your system because it would do immense damage).
Could be scaled up or down for different needs.
Far more efficient than vapor heat pipes currently used for cooling GPUs.

This is one of the most interesting patents to come out of Cupertino in a long time.

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Apple Macintosh, Magnet, Apple Inc., Desktops, Hardware, Adrian Kingsley-Hughes

Adrian Kingsley-Hughes is an internationally published technology author who has devoted over a decade to helping users get the most from technology.

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RE: Apple's obsession with magnets could mean better cooling for your next Mac

The magnetic PSU connectors have to be one of the coolest devices of the past 10 years and likely saved many a laptop so, it will be interesting to see what they do here.
Peter Perry
28th Jan
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Better to just have smaller chips that generate less hear to start with

Yeah its a cool idea but better suited to applications not involving electronics. Having a magnetic field source that close to the cpu/gpu/ram/ssd etc. sounds risky. And what makes you think this couldnt leak? If not in the useful life then later in the landfil when the device gets crushed. Yes lots of electronics end up in landfils, not recycling, just like todays mercury filled CFL light bulbs do, even in California. If you generate less heat to start with your going to get longer battery life as well. And you can take advantage of another energy free cooling mechanism, airflow. Heated air rises, which draws in cooler air to replace it. With no toxic ferrofluids to worry about when a truck runs over your phone.
Johnny Vegas
28th Jan
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Wouldn't Work

@Johnny Vegas---To generate a convection current sufficient to cool a CPU, mandates a mechanical accelerator.
PreachJohn
28th Jan
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Dissipating 100W is different than 1W or 1mW

@PreachJohn
You are correct, currently.

Yet the above post specifically mentions lower power consumption chips, requiring less cooling? At some point in evolution, simple air convection would work, for free, no power, no moving parts either...

And I have an Audio Technica bubble level for my Technics turntable. Well, over time, all liquids evaporate somehow, even in 'supposedly' sealed systems...

Just look at electrolytic capacitors for instance, they are sealed (with safety vents in case of catastrophic failure) for all practical purposes? Yet they lose capacity (capacitance) over time? Even sealed rechargeable batteries ultimately die?

Should a mechanical failure arise (such as dropping the unit), wouldn't that ferrofluid short out and destroy all adjacent electronics circuitry?

For reference purposes, a single 20W soldering iron can melt solder....

~~~~~~~~
It's not what you look at that matters; it's what you see.
~ Henry David Thoreau

Any intelligent fool can make things bigger, more complex, and more violent. It takes a touch of genius -- and a lot of courage -- to move in the opposite direction.
~ Albert Einstein

If you change the way you look at things, the things you look at change.
~ Wayne Dyer
WinTard
29th Jan
- Flag
RE: Apple's obsession with magnets could mean better cooling for your next Mac

@Johnny Vegas
Maybe not too risky. Apple and everyone else ought to take back the dead electronics for recycling. Maybe there should be a 'deposit' required on each system, like with glass bottles. In any case it should not be hard to recycle the fluid if it is in a copper pipe or something and is "made for recycling", which is smart. I hope people who are smart enough to use a computer are smart enough not to throw it in the landfill.

@WinTard
I'm not sure it would leak. I have many, many 40-70 year old oil-filled high voltage capacitors in the equipment here and very few have ever leaked. Maybe 1 out of 100. None of the big ones (50uF/7500V) Consider the sealing technology of those times. I'm sure Apple can make a good seal. Solder it. to recycle, melt the solder bead & drain.
opcom
30th Jan
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RE: Apple's obsession with magnets could mean better cooling for your next Mac

This description sounds suspiciously like a perpetual motion device.....
jgm@...
28th Jan
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RE: Apple's obsession with magnets could mean better cooling for your next Mac

@jgm@...

Not really, as it relies on the chips being heated by use. This system doesn't make power.
msalzberg
28th Jan
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No More Than...

@jgm@...all wheel drive using silicon joints. As wheel slippage increases, friction is generated, which translates into heat. This then increases the viscosity of the silicon, connecting those wheels to drive. When silicon cools, it becomes more fluid, no longer transferring power to the wheels.
PreachJohn
28th Jan
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Other alternatives..

Mini sealed Stirling cycle units, could also transport heat out of the CPU and be carried away by a regular fan. Any Stirling cycle engine run backwards will act as a refrigerator. The CPU heat would activate it, very few moving parts, totally sealed, and needing only sealed gas as a thermal conductor. Several gases will work with these systems. Most of the energy of heat is dissipated as mechanical energy within the Stirling engine. I don't think their is a size restriction on these systems. Perhaps even nano sized units would work.
JCitizen
29th Jan
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Re-invent the wheel?

I've been using ferro-fluid cooling for eons in my (real) High-Fidelity speakers. Same goes for ferro-fluid bearings in hard-drives and heat-sink fans.

Don't believe me? Just Google ferrofluid cooling
http://lmgtfy.com/?q=ferrofluid+cooling
About 967,000 results (0.13 seconds)

or ferrofluid heat sink
http://lmgtfy.com/?q=ferrofluid+heat+sink
About 525,000 results (0.15 seconds)

leading to:
http://lmgtfy.com/?q=Patent+US20070058340+-+Heat+sink+ by Sun Microsystems March 15, 2007

What's new, revolutionary, magical, incredible, awesome about that from Apple?

As usual, good luck when the patent gets validated through a court of law. Merely having a patent isn't sufficient. Except for Apple who has enough chutzpah to patent the obvious, then count on their war chest to ~~intimidate~~ bully smaller opponents. Except that in the cases of Microsoft, that was insanity; then with Samsung, that is pure stupidity.

I suppose that is what free-enterprise is all about?

~~~~~~~~~~~
The great Robert A. Heinlein chose to spend far too many resources fighting patent applications for water beds; which he first introduced in the novel "Beyond This Horizon" in 1942. The Patent Office seemingly only looks at whether a thing has been previously patented, not whether it's actually a novel idea that is not currently in use by professionals or whether it's been detailed in literature. It's a mess; a ponzi scheme that should be torn down.
~ On September 01, 2011, at 3:13 PM, theHedgehog on fool wrote:

Profits, like sausages... are esteemed most by those who know least about what goes into them.
~ Alvin Toffler
WinTard
29th Jan
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Further interesting reading on the topic of ferrofluids

New Scientist, 25 September 1980
Magnetic liquids - the new technology
http: // bit . ly/ A5jXNz

http://www.ferrotec.com/technology/ferrofluid/

http://en.wikipedia.org/wiki/Ferrofluid#Heat_transfer
Heat transfer

An external magnetic field imposed on a ferrofluid with varying susceptibility (e.g., because of a temperature gradient) results in a nonuniform magnetic body force, which leads to a form of heat transfer called thermomagnetic convection. This form of heat transfer can be useful when conventional convection heat transfer is inadequate; e.g., in miniature microscale devices or under reduced gravity conditions.

Ferrofluids are commonly used in loudspeakers to remove heat from the voice coil, and to passively damp the movement of the cone. They reside in what would normally be the air gap around the voice coil, held in place by the speaker's magnet. Since ferrofluids are paramagnetic, they obey Curie's law, thus become less magnetic at higher temperatures. A strong magnet placed near the voice coil (which produces heat) will attract cold ferrofluid more than hot ferrofluid thus forcing the heated ferrofluid away from the electric voice coil and toward a heat sink. This is an efficient cooling method which requires no additional energy input.[7]

Ferrofluids of suitable composition can exhibit extremely large enhancement in thermal conductivity (k; ~300% of the base fluid thermal conductivity). The large enhancement in k is due to the efficient transport of heat through percolating nanoparticle paths. Special magnetic nanofluids with tunable thermal conductivity to viscosity ratio can be used as multifunctional ???smart materials??? that can remove heat and also arrest vibrations (damper). Such fluids may find applications in microfluidic devices and microelectromechanical systems (MEMS).[8]

I do appreciate the fact the article states:
A magnet acts as a pump (a pump with no moving parts whatsoever, and needs no power or maintenence [sic])

~~~~~~~~~~
Trying to determine what is going on in the world by reading newspapers is like trying to tell the time by watching the second hand of a clock.
~ Ben Hecht

There are two primary choices in life: to accept conditions as they exist, or accept the responsibility for changing them.
~ Dr. Denis Waitley

If you wish to travel far and fast, travel light. Take off all your envies, jealousies, unforgiveness, selfishness, and fears.
~ Glenn Clark
WinTard
29th Jan
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Aha. What new thing does Apple add, then?

@WinTard
I'm not familiar with the prior art or Apple's patent - in your opinion have they improved the state of the art with any new ideas, or is it a silly patent that shouldn't be granted to them?
exolon
31st Jan
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Not new

Like most Apple"inventions" - it's not new or a real invention - won't stop them trying to patent others ideas though
archangel9999
30th Jan
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Better than phase-transition?

Modern heat pipes like you find in your laptop between the CPU heatsink and the cooling fans make use of a small amount of fluid inside the tube filled with a sintered material to vastly increase the internal surface area. The liquid, typically an alcohol, and the pressure inside the tube, is selected such that the liquid will boil in the hot zone and condense in the cold zone without the use of pumps or any other moving part. Phase change heat transfer can far exceed more conventional convective or conductive cooling, which is why factories still use the old-fashioned cooling tower (it's very effective and cheap to operate).

While the magnetically pumped fluid sounds interesting, I would want to see some real statistics as to the provided heat transfer per unit mass and cost* of the cooler to get an apples-to-apples comparison (pun intended).
(* Not only financial, but in terms of longevity, environmental concern, etc.)

In other words, I could re-invent the wheel into a very cool-looking octagon shape, but you probably would not want to drive down the road on one.
JJMach
30th Jan
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When all you have is a hammer...

...every problem looks like a nail.

I suspect that speakers use ferro-fluid cooling because they can take advantage of the already present, strong magnetic fields of the voice coil.
JJMach
30th Jan
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