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The Fanless Spinning Heatsink

CmdrTaco posted more than 3 years ago | from the get-your-whirl-on dept.

Hardware Hacking 380

An anonymous reader writes "There's a fundamental flaw with fan-and-heatsink cooling systems: no matter how hard the fan blows, a boundary layer of motionless, highly-insulating air remains on the heatsink. You can increase the size of the heatsink and you can blow more air, but ultimately the boundary layer prevents the system from being efficient. But what if you did away with the fan? What if the heatsink itself rotated? Well, believe it or not, rotating the heat exchanger obliterates the boundary layer, removes the need for a fan, and it's so efficient that it can operate at low and very quiet speeds. That's exactly what the Air Bearing Heat Exchanger, developed by Jeff Koplow of the Sandia National Laboratories, has developed. It's even intrinsically immune to the build up of dust and detritus!"

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Fanless doesn't seem to be an accurate description (3, Insightful)

Bill_the_Engineer (772575) | more than 3 years ago | (#36733492)

I think a better description would be a heatsink that is a fan or probably more accurately an impeller but without the tube enclosure.

Re:Fanless doesn't seem to be an accurate descript (0, Troll)

EraserMouseMan (847479) | more than 3 years ago | (#36733654)

I think my Macs have had this for a long time. I guess this is trickling down to the PC people now.

Re:Fanless doesn't seem to be an accurate descript (1)

Osgeld (1900440) | more than 3 years ago | (#36733732)

you thought wrong, they use standard box fans or squirrel cages

Re:Fanless doesn't seem to be an accurate descript (4, Funny)

ShavedOrangutan (1930630) | more than 3 years ago | (#36733884)

... made from the hooves of a unicorn.

Re:Fanless doesn't seem to be an accurate descript (1)

Osgeld (1900440) | more than 3 years ago | (#36734044)

LOL yes I forgot about that part

fr1stage postage (-1)

Anonymous Coward | more than 3 years ago | (#36733494)

'sup 20721 posse

Hot pussy (-1)

Anonymous Coward | more than 3 years ago | (#36733500)

God I love hot wet pussy. Even if it doesn't have a heat sink

Re:Hot pussy (0)

Anonymous Coward | more than 3 years ago | (#36733916)

But what about the heat stink??

Re:Hot pussy (0, Offtopic)

Chrisq (894406) | more than 3 years ago | (#36734004)

God I love hot wet pussy. Even if it doesn't have a heat sink

Didn't you know. If your dick stays still and her cunt moves the boundary layer will stop her from getting pregnant.

what?? (-1, Troll)

assstallion (2209046) | more than 3 years ago | (#36733526)

what boundary layer? what the fuck is this guy talking about? if you have a heat sink that spins, how is it attached to the cpu? oh, that little part doesn't spin, does it. well, guess what then, this guy invented a huge massive fan, not a heat sink. and yes, that huge massive fan, is mounted to a stationary tiny little heat sink. sink. sink.

Re:what?? (4, Informative)

Bill_the_Engineer (772575) | more than 3 years ago | (#36733562)

I think the distinction between a traditional fan + heatsink combo and what is described in the article is that the impeller blades are dissipating the heat instead of merely blowing cooler air over the fins of a stationary heatsink.

Re:what?? (1)

Bill_the_Engineer (772575) | more than 3 years ago | (#36733580)

I meant singular impeller not plural impellers. For those who don't read the article there is only one moving impeller.

Re:what?? (5, Funny)

Anonymous Coward | more than 3 years ago | (#36733592)

You sound angry. At thermodynamics.

Re:what?? (2)

Xacid (560407) | more than 3 years ago | (#36733636)

I think he just had an exothermic reaction.

Re:what?? (2, Informative)

S.O.B. (136083) | more than 3 years ago | (#36733696)

This is all explained in the article and PDF.

Don't come here and start mouthing off like you know what you're talking about when you clearly are too lazy to get past the summary and expect everyone else to do the work explaining it for you. You must be an MBA graduate.

Re:what?? (0)

Anonymous Coward | more than 3 years ago | (#36733770)

No Sir, I believe he's a D.S.

Re:what?? (0)

Anonymous Coward | more than 3 years ago | (#36734080)

why would you assume he's graduated from anywhere ?

Re:what?? (0)

Anonymous Coward | more than 3 years ago | (#36733800)

what boundary layer? what the fuck is this guy talking about?

What the fuck are you talking about? Either dispute his claim with facts, or shut the hell up because you're not a research engineer and he is.

Yes, I am a walking [citation needed].

Re:what?? (0)

Anonymous Coward | more than 3 years ago | (#36733850)

The heat sink is not attached to the CPU directly - it sits on a one micron air gap. That's why it's an "air bearing heat exchanger". Most of the PDF you didn't read is about how heat transfers through a shearing air gap to a rotating unshrouded impeller thing.

Re:what?? (0)

Anonymous Coward | more than 3 years ago | (#36733880)

what boundary layer? what the fuck is this guy talking about? if you have a heat sink that spins, how is it attached to the cpu?

According to the words located the title, the rotating part of the heatsink is thermally coupled via an air gap to a heat spreading base which is physically attached to the heat source.

Re:what?? (3, Informative)

operagost (62405) | more than 3 years ago | (#36733888)

According to the report, which is rather comprehensive, the air gap is about .03 mm and has a relatively low thermal resistance due to "convective mixing". As for the "boundary layer", this appears to be his source:

Koplow, J. P., HEAT EXCHANGER DEVICE AND METHOD FOR HEAT REMOVAL OR
TRANSFER, USPTO Application #: 20090199997.

Re:what?? (4, Informative)

tibit (1762298) | more than 3 years ago | (#36733996)

I've read the paper and what you said is just silly, not insightful. The heat sink is separated from the base plate by a layer of air on the order of 1E-5m thick. This layer of air experiences large shear stress that keeps its thermal resistance low. It's basically an air bearing for the spinning heat sink. The stackup is thus:

1. CPU
2. Disk-shaped base plate
3. Air gap
4. Heat sink impeller

The major difference is that in normal coolers, fan has no heat dissipating function at al. There's no functional heat flow through the fan. In this design, the fan is the heatsink: heat does flow through it, and that's what makes it work so well.

From what I can tell, it's a truly revolutionary device. It has 5-10x lower thermal resistance than regular coolers, consumes ~5x less power than coolers of same capacity, and generates less acoustic noise to boot (it wasn't quantified, though). Ah, and also it doesn't get fouled by dust: ever notice how in usual CPU coolers the fan is usually clean or just sprinked with dust, when the heatsink is pretty much plugged with dust? In this device, the heatsink spins, so it stays clean, just like a fan would.

Whoever commercializes this for the HVAC market will be financially set, as in "playboy mansion" financially set :)

Re:what?? (5, Funny)

serviscope_minor (664417) | more than 3 years ago | (#36734042)

it's a truly revolutionary device

haha! Excellent pun.

Transfer? (0)

Anonymous Coward | more than 3 years ago | (#36733546)

And just how does the heat get transferred from the object needing cooling to the heat sink itself? Or does it rotate as well...?

Re:Transfer? (1, Flamebait)

couchslug (175151) | more than 3 years ago | (#36733598)

Read The Fucking Article, shithead.

Re:Transfer? (1)

S.O.B. (136083) | more than 3 years ago | (#36733604)

Lazy AC that wants to be spoon fed information.

Go home and change your diaper.

Re:Transfer? (5, Funny)

logjon (1411219) | more than 3 years ago | (#36733668)

yes. the spinning heat sink is attached to a spinning cpu, which is in turn attached to a spinning motherboard mounted to a spinning case. these are only available in funhouses btw.

Re:Transfer? (0)

Anonymous Coward | more than 3 years ago | (#36733832)

mod parent up.

Re:Transfer? (0)

Anonymous Coward | more than 3 years ago | (#36734120)

why not spin the socket as well?

Re:Transfer? (1)

nschubach (922175) | more than 3 years ago | (#36734172)

While an entertaining post, one could speculate that building a spinning computer should not actually be that hard these days. You probably couldn't use spinning hard drives but SSD should work fine. Power could easily be supplied with some bushings. The hardest part would be video out, but I think there are high speed wireless video solutions. If not, you may be able to get away with bushings for this as well but your contact area has to be pretty consistent. The rest of the system could be wireless (keyboard, mouse, etc.)

I'm curious... (1)

AngryDeuce (2205124) | more than 3 years ago | (#36733554)

Doesn't there still need to be a stationary connection to the rotating heatsink since the CPU is stationary? And if that's the case, how does this help prevent the boundary layer? Seems like one would still be able to form between the CPU surface the the rotating heatsink.

I'm no scientist, however, so I'm probably making a false assumption. But I am curious how this alleviates that boundary layer...

Re:I'm curious... (0)

Anonymous Coward | more than 3 years ago | (#36733610)

The whole article smells like BS to me. FTFA:

The Sandia Cooler may also be the technology that smashes down the “Thermal Brick Wall” that is preventing computer chips from moving beyond 3GHz.

Apparently, someone forgot to tell chip makers about this "Brick Wall". Seriously, sounds like the author is making stuff up with absolutely no idea what he is talking about.

Re:I'm curious... (1)

Anonymous Coward | more than 3 years ago | (#36734250)

Apparently, someone forgot to tell chip makers about this "Brick Wall". Seriously, sounds like the author is making stuff up with absolutely no idea what he is talking about.

Contrary to your complete stupidity, the "chip makers", subscribe to his news letter. There are several significant issues with modern CPUs. One of the most prevalent issues is heat dissipation. Thus, accurately described as a "brick wall", as it is effectively preventing the creation of faster, general purpose CPUs.

Why does slashdot seem to attract so many completely fucking stupid morons who like to pretend they know something when in fact is obvious they known absolutely nothing anything anything. Holy shit you are really fucking stupid.

Re:I'm curious... (1)

Anonymous Coward | more than 3 years ago | (#36733616)

Doesn't there still need to be a stationary connection to the rotating heatsink since the CPU is stationary? And if that's the case, how does this help prevent the boundary layer? Seems like one would still be able to form between the CPU surface the the rotating heatsink.

I'm no scientist, however, so I'm probably making a false assumption. But I am curious how this alleviates that boundary layer...

http://www.extremetech.com/wp-content/uploads/2011/07/cooler3-348x196.jpg

Stationary base plate marked in photo. Also labeled with 0.001" of air between stationary base plate and moving fan part.

Re:I'm curious... (2)

dpilot (134227) | more than 3 years ago | (#36734228)

A 1 micron air gap... Now not only can the heads on our harddrives crash, our heatsinks can crash, too.

Re:I'm curious... (1)

S.O.B. (136083) | more than 3 years ago | (#36733634)

The article and the PDF will answer all your questions.

Re:I'm curious... (1)

AngryDeuce (2205124) | more than 3 years ago | (#36733690)

To be fair, the article doesn't address that question at all. Haven't read the PDF, though, as I'm at work and not currently able to. Anyone care to paraphrase, or shall I wait until I get home?

Re:I'm curious... (1)

PeterKraus (1244558) | more than 3 years ago | (#36733842)

From TFA:

The cooler consists of a static metal baseplate, which is connected to the CPU, GPU, or other hot object, and a finned, rotating heat exchanger that are cushioned by a thin (0.001-inch) layer of air. As the metal blades spin, centrifugal force kicks up the air and throws it up and outwards, much like an impeller, creating a cooling effect.

Wasn't that hard, was it.

Re:I'm curious... (0)

Anonymous Coward | more than 3 years ago | (#36734292)

I have a custom case consisting of 2 20" box fans on each side...I'm pretty sure my setup completely obliterates that .001 inch layer of air.

Re:I'm curious... (0)

Anonymous Coward | more than 3 years ago | (#36733998)

The PDF is very math-intensive, but basically: Small (1 micron) air gap between CPU and spinning impeller. Heat transfers into the air gap, which is under constant shear from the impeller. Hot air is flung outward by impeller blades.

Re:I'm curious... (2)

Silvanis (152728) | more than 3 years ago | (#36734012)

Essentially, they claim the really thin (~0.03mm) layer of air between the stationary plate and the rotating heatsink is thermally conductive and agitated by the rotation, so no static boundary layer.

Re:I'm curious... (4, Informative)

goofy183 (451746) | more than 3 years ago | (#36734104)

I had the same question but it is very well addressed in the PDF:

During operation, these two flat surfaces are a separated by a thin (~0.03 mm) air gap, much like the bottom surface of an air hockey puck and the top surface of an air hockey table. This air gap is a hydrodynamic gas bearing, analogous to those used to support the read/write head of computer disk drive (but with many orders of magnitude looser mechanical tolerances).
Heat flows from the stationary aluminum base plate to the rotating heat-sink-impeller through this 0.03-mm-thick circular disk of air. As shown later in Figure 18, this air-filled thermal interface has very low thermal resistance and is in no way a limiting factor to device performance; its cross sectional area is large relative to its thickness, and because the air that occupies the gap region is violently sheared between the lower surface (stationary) and the upper surface (rotating at several thousand rpm). The convective mixing provided by this shearing effect provides a several-fold increase in thermal conductivity of the air in the gap region.

The PDF also goes into how this tech could have serious applications in things like home AC and refrigerator heat exchangers as well.

Re:I'm curious... (1)

Will Fisher (731585) | more than 3 years ago | (#36734194)

There is 0.3mm of air between the base plate and the spinning impeller. Because this air gap is thin, wide and sheared (i.e, the top part is spinning and the bottom part isn't - so you get lots of convection), the thermal resistance of the air gap is actually very low.

Re:I'm curious... (0)

couchslug (175151) | more than 3 years ago | (#36733648)

It describes how in the article.

Re:I'm curious... (0)

Anonymous Coward | more than 3 years ago | (#36733674)

Apparently, the premise is that the insulation afforded by the air gap is proportional to its width. So, the rotating portion must be very close to the base.

From TFA:

Heat flows from the stationary aluminum base plate to the rotating heat-sink-impeller
through this 0.03-mm-thick circular disk of air. As shown later in Figure 18, this air-filled
thermal interface has very low thermal resistance and is in no way a limiting factor to device
performance; its cross sectional area is large relative to its thickness, and because the air that
occupies the gap region is violently sheared between the lower surface (stationary) and the
upper surface (rotating at several thousand rpm).

Re:I'm curious... (0)

Anonymous Coward | more than 3 years ago | (#36733688)

Doesn't there still need to be a stationary connection to the rotating heatsink since the CPU is stationary?

I say rotate the CPU also, I wonder why no one has thought of this yet...*quietly submits patent*

Re:I'm curious... (0)

Anonymous Coward | more than 3 years ago | (#36733748)

Just mount your PC on a centrifuge! How come nobody thought about that before?

Re:I'm curious... (1)

chocapix (1595613) | more than 3 years ago | (#36734210)

But how do you use a spinning computer if you're not spinning?

Just spin the whole world in a cold medium and be done with it. 0.0007rpm at 2.7 Kelvin sounds about right, what do you guys think?

Re:I'm curious... (1)

MightyYar (622222) | more than 3 years ago | (#36733716)

But I am curious how this alleviates that boundary layer...

Maybe it's a side-effect of using an air bearing? Little rotating concentrated jets of air blowing down on the hot metal plate....

Re:I'm curious... (0)

Anonymous Coward | more than 3 years ago | (#36733882)

It is in the article. There is a small cushion of air between the rotating sink and the item to be cooled. it's about as wide as the clearance of a hard drive head but not as sensitive. the spinning parts cause it to act as a great conductor even though there is no physical connection. Do read the article and PDF.

Re:I'm curious... (0)

Anonymous Coward | more than 3 years ago | (#36733726)

The entire computer spins. Duh. Now stop asking questions and go buy the fancy new toy.

Re:I'm curious... (1)

Anonymous Coward | more than 3 years ago | (#36733810)

They leave a sub-millimeter gap of air between the aluminum plate on top of the device being cooled, and the underside of the spinning heat sink. Since this layer of air is violently disturbed by rotation, it conducts heat surprisingly well, rending physical contact needless. Furthermore, it does not require precise bearings to maintain precise separation from the base plate, as hydrodynamic effects stabilize the air gap fairly well.

Re:I'm curious... (1)

mcvos (645701) | more than 3 years ago | (#36734152)

Doesn't that mean that the impeller is actually a fan and not a heatsink? I mean, if it just sucks air over the aluminium plate on top of the CPU, doesn't that mean it's that layer of hot air that's blow away, rather than the heatsink actually getting hot and then blowing the air away?

I have some trouble grasping how even a really thin layer of air can conduct heat so efficiently from one solid object to another.

Re:I'm curious... (1)

Zerth (26112) | more than 3 years ago | (#36733952)

The heat transfers through the air bearing, which is very thin and in the paper is dry nitrogen gas, IIRC.

Re:I'm curious... (3, Insightful)

tibit (1762298) | more than 3 years ago | (#36734040)

Nope, the "connection" is a thin (1E-5m) air gap experiencing high shearing and thus providing very low thermal resistance. The gap's thermal resistance contributes very little (on the order of 10%) to the overall thermal resistance of the cooler. It is a truly revolutionary design, no shit here.

Re:I'm curious... (5, Informative)

canajin56 (660655) | more than 3 years ago | (#36734058)

Yes, a layer of air does form between the heat spreader base, and the base of the rotating heatsink. This is called an air bearing. It's extremely thin, and for that reason an excellent thermal conductor even though it's conducting heat poorly. You see, it has a surface area of 100 cm squared, but it is less than 0.03 mm thick. So, heat transfer is inefficient, but its so thin as to be negligible.

And no boundary layer forms (well, it does but it is reduced by a factor of 10) on the fins because they are rotating. The equations for fluid dynamics are quite different between an inertial reference frame and a rotating one. Basically, the fluid cannot settle into little pockets because the (fictional) centripetal force is pushing it outwards along the fin channels.

Idk... (0)

Anonymous Coward | more than 3 years ago | (#36733566)

This is just a fan made out of heatsink material. While it might be more 'efficient'. Which remains to be seen. somehow i don't think it can meet the hype.

Won't be immune to dust anymore than a fan is either. (they're not)

Re:Idk... (1)

TheCarp (96830) | more than 3 years ago | (#36733626)

I mostly agree but, I do have to point out... fans ARE pretty resistent to dust....in compairson to stationary parts near fans (like a traditional heat sink). While fan blades to accumulate dust, it happens much more slowly than the stationary parts near them.

A notable exception do seem to be ceiling fans, but they tend to be off much of the time and sit stationary and horizontal.

Re:Idk... (1)

crashumbc (1221174) | more than 3 years ago | (#36734148)

Ceiling fans also usually operate at very low speeds compared other fans...

Homeless (3, Funny)

phrostie (121428) | more than 3 years ago | (#36733578)

But think of all the homeless Dust puppies!!!

have you no shame?

Still has a boundary layer. (0, Troll)

HornWumpus (783565) | more than 3 years ago | (#36733590)

This story is pure bullshit.

Airplanes have boundary layers attached in flight.

All you need to do to a heat-sink is rough up the surface enough that the boundary layer is turbulent. It's not like drag is an issue.

The first point in favor of this heat-sink is pure bullshit. Want to bet everything else is also bullshit.

How well do bearings conduct heat?

WTF happened to /.

Re:Still has a boundary layer. (4, Insightful)

Verdatum (1257828) | more than 3 years ago | (#36733722)

You sir, need a hug. It's a pretty good article.

Re:Still has a boundary layer. (4, Funny)

Bucc5062 (856482) | more than 3 years ago | (#36733904)

+1 sweetness factor, such a rare moment in /. land.

Re:Still has a boundary layer. (0)

Colonel Korn (1258968) | more than 3 years ago | (#36733752)

This story is pure bullshit.

Airplanes have boundary layers attached in flight.

All you need to do to a heat-sink is rough up the surface enough that the boundary layer is turbulent. It's not like drag is an issue.

The first point in favor of this heat-sink is pure bullshit. Want to bet everything else is also bullshit.

How well do bearings conduct heat?

WTF happened to /.

This needs to be modded up. There will be many other comments with objections, but we need to get +5 informative or insightful attached to the 100% unarguable reality that spinning a surface absolutely doesn't eliminate the boundary layer. People should take fluid mechanics classes before writing about boundary layers.

Re:Still has a boundary layer. (2)

iteyoidar (972700) | more than 3 years ago | (#36733846)

If you read the PDF article, it says it works like an air-hockey puck or hard-drive platter, there's an extremely thin layer of air between the spinning surface which is under high shear which is conducive to heat conductivity. The PDF goes on to explain that this dramatically reduces the size of the boundary layer, not eliminate it as the summary says (since this isn't even logical what I remember of my fluids class). I didn't read the whole thing but I think it's the fact that the heat sink blades themselves are spinning at very high speeds, rather than having dirty air blown on them, that prevents dust build-up.

Re:Still has a boundary layer. (1)

iteyoidar (972700) | more than 3 years ago | (#36733886)

More to the point, the boundary layer shear is what enables this concept to work at all

Re:Still has a boundary layer. (1)

Hognoxious (631665) | more than 3 years ago | (#36733946)

IANAFD but it would seem intuitive that moving an object at velocity X through air is the same (from the object's POV) as moving air at the same velocity[1] over the stationary object.

Otherwise wind tunnels would be a total waste of time.

[1] In the opposite direction, so -X, to be pedantic.

Re:Still has a boundary layer. (1)

AlecC (512609) | more than 3 years ago | (#36734230)

But in a conventional system, the air is moving fastest over the cool fan, and much slower over the hot heat sink - in fact, very slowly over the last fraction of a millimetre. In the system, the air is moving fastest over the hot fan.

Re:Still has a boundary layer. (1)

Kookus (653170) | more than 3 years ago | (#36733948)

Do airplanes exert centripetal forces on the surfaces exposed to the moving air?
That would be a sweet airplane ride!

I think the better analogy would be to prove that the propellers on the planes still have boundary layers.

Re:Still has a boundary layer. (1)

Anonymous Coward | more than 3 years ago | (#36734184)

I think the better analogy would be to prove that the propellers on the planes still have boundary layers.

they do. since in the real viscous world, you can't have air moving directly on a surface. the air has to transition to whatever the speed of the surface is over some distance (however small). this is what we call a boundary layer.

Re:Still has a boundary layer. (2)

slim (1652) | more than 3 years ago | (#36733756)

*Man* you read and analysed those 44 pages of maths quickly.

Re:Still has a boundary layer. (1)

rubycodez (864176) | more than 3 years ago | (#36733894)

Some of us had to read much more than 44 pages as we studied fluid dynamics in college. Apparently, there are rules for such things in this universe with no known exceptions.

The article is bull feces.

Re:Still has a boundary layer. (0)

Anonymous Coward | more than 3 years ago | (#36733908)

No, he saw the bit about eliminating the boundary layer in the summary and called bullshit on it.

And rightly so, unless the basics of fluid mechanics have somehow changed overnight.

Re:Still has a boundary layer. (1, Insightful)

Anonymous Coward | more than 3 years ago | (#36734056)

It's only "rightly so" if the summary accurately summarized the article. It doesn't. He didn't read it he just read the summary and wanted to post fast for physics cred.

And that's the saddest part of all. *sigh*

Someone posted it above. The actual article says it doesn't get rid of the boundary layer just significantly reduces it. He calls BS that the boundary layer is eliminated but the article doesn't say that only the summary does.

Re:Still has a boundary layer. (3, Interesting)

vlm (69642) | more than 3 years ago | (#36734212)

*Man* you read and analysed those 44 pages of maths quickly.

I skimmed them.

It seemed to very carefully avoid the issue of the bearing's heat conduction ability while explaining how spinning a heatsink does reduce its thermal resistance vs merely blowing air upon it. So you decrease the resistance at one end while ignoring the increase at the other. Hmm.

The other mystery is the straw dog of cheap and easy to machine heatsink designs (you've all seen them) have moderately bad boundary layer problems, so rather than a more elaborately modeled and machined heatsink design, or even more simply, a larger heatsink, the solution is a very complicated, hard to model, and hard to machine rotating heatsink. So, why not just put the hydrodynamic engineering hours and CNC machining hours into a GOOD passive sink that might work just as well? Or invest in a couple more dollars of aluminum, or skip it all and go for broke with waterblocks. Who knows?

Is there a middle ground for this design to live in between cheap and easy and inefficient non-moving sinks and much higher performance (and cost) waterblocks? I'm guessing, no. Not in any electronic system I've worked on (not just computers, but high power RF amps, high power audio, high power VFDs, etc)

The other problem is it makes for a more brittle design. Now you can usually shut down a system automatically when the cooling system stops, due to thermal mass, limited natural convection cooling, etc. With this, it'll be smaller and lighter, can you shut down in time to avoid frying the CPU (physically) or crashing the filesystem? Its going to make OTHER parts of the system design more complex, not just the cooling system.

Cool engineering (pun intended) but I'm unimpressed from an economic standpoint. It will probably cost more than the alternatives. Unless you're just trying to avoid a patent or whatever.

Re:Still has a boundary layer. (1)

Xacid (560407) | more than 3 years ago | (#36733764)

Personally I think this is a neat concept and would like to see some how these pan out in the real world. While there's nothing wrong with being skeptical by any means there seems to be some merit behind this. I'm particularly curious to see how this would perform in an HVAC system.

Regarding your question about bearings conducting heat - I was wondering the same question. I wonder if there's a way to make bearings specifically for this application with heat transfer in mind while still providing decent performance.

Re:Still has a boundary layer. (1)

queazocotal (915608) | more than 3 years ago | (#36733774)

Well - yes.
You can avoid dust in that manner.
But only if you wind up the fan speed to several tens of thousands of RPM, and make them sound like your case is about to explode.

And also - read the article - the heat is transferred by the conductive fan rotating over a thermal plate with a .001" clearance.
This actively massively stirred air has fairly low thermal resistance.

I note the pressure guage next to the device.
This is presumably connected to a large compressor, providing reasonable rates of high pressure air, as you need for air bearings.
The average PC however doesn't actually have this.

Re:Still has a boundary layer. (1)

UnknowingFool (672806) | more than 3 years ago | (#36734014)

I'm curious to see this applied to a consumer CPU fan. Of course it will have to undergo some testing. It may be dust resistant but I don't know if it is Cheetos resistant which it needs to be for your average slashdotter. ;)

Re:Still has a boundary layer. (0)

Anonymous Coward | more than 3 years ago | (#36733872)

>> The Sandia Cooler may also be the technology that smashes down the “Thermal Brick Wall” that is preventing computer chips from moving beyond 3GHz.

WTF ?

Re:Still has a boundary layer. (0)

Anonymous Coward | more than 3 years ago | (#36733918)

Actually quite a few critical surfaces on higher performance airplanes will be perforated with small holes with a vacuum behind to suck in and eliminate the boundary layer.

Apparently with the air bearing, since the air is for most purposes comparatively static and under pressure, transfers the heat quite effectively.
 

Re:Still has a boundary layer. (2)

kwikrick (755625) | more than 3 years ago | (#36734060)

You're wrong.

Basically, the layer of air between the thermal spreader (base plate) and the impeller if very thin and very turbulent, because it is 'grinded' between the the impeller and the base plate. That actually makes it a very good heat conductor.

It's explained very well in the Sandia Labs paper. Seems like a very plausible and good design.

Re:Still has a boundary layer. (1)

tibit (1762298) | more than 3 years ago | (#36734092)

Look silly, proof is in the pudding. Off-the-shelf CPU coolers have about 0.8C/W thermal resistances, this thing has demonstrated 0.2C/W in version 1 prototype, and version 2 is estimated to lower it to 0.1C/W.

How well do bearings conduct heat?

An air bearing? Very fucking well. So much so that its thermal resistance is an order of magnitude lower than the thermal resistance of the heatsink-to-air!

Re:Still has a boundary layer. (1)

mswhippingboy (754599) | more than 3 years ago | (#36734112)

Wow. Maybe Sandia should have just given you a call instead of all that research since you have all the answers.

No, turbulence mitigates the boundary layer problem, but does not remove it. This approach apparently, while not removing it completely, reduces it to the point where it's impact on the efficiency of the heat exchanger is negligible.

Re:Still has a boundary layer. (0)

Anonymous Coward | more than 3 years ago | (#36734166)

It eradicates the problem with dust deposits. A bearing with heat conductive material inside it could transfer heat better. I've dled the article and skimmed through it but it looks like it doesn't use your typical bearing mechanism. Someone that is knowledgeable on the topic is welcomed to explain further.

Re:Still has a boundary layer. (1)

AlecC (512609) | more than 3 years ago | (#36734178)

This story is pure bullshit.

Airplanes have boundary layers attached in flight.

All you need to do to a heat-sink is rough up the surface enough that the boundary layer is turbulent. It's not like drag is an issue.

The first point in favor of this heat-sink is pure bullshit. Want to bet everything else is also bullshit.

How well do bearings conduct heat?

WTF happened to /.

There are two significant differences between wings and heat sinks. Firstly, wings are moving compared to the ambient air, and heat sinks are not. Secondly, for aircraft the boundary layer is a good thing, and designers try and make is stick as much as possible (though the do put in widgets to ensure that when it breaks off and goes turbulent, it does so progressively, not suddenly). Roughening, on the appropriate scale, is used to increase boundary layer adhesion - the "golf-ball" effect. It is also being tried on ships, especially racing yachts (the "shark-skin" effect). The desired effect is the exact opposite to that here: wings want boundary layers, heat sinks don't.

Re:Still has a boundary layer. (2)

harperska (1376103) | more than 3 years ago | (#36734180)

I know this is /., but the lack of TFA reading comprehension for this article is crazy even for slashdot standards.

The PDF never claims that the spinning heat sink eliminates the boundary layer. They only claim that spinning the heat sink reduces the boundary layer thickness by several orders of magnitude. And it makes sense, as the speed of air over the impeller blades moving at several thousand RPM is quite a bit faster than the speed of air that can be pushed over a static heat sink by a traditional fan. The faster the airflow, the smaller the boundary layer. The only way to get air moving that fast over a static heat sink is with a jet, and establishing such a jet in a computer enclosure environment exceeds reasonable power requirements.

Re:Still has a boundary layer. (5, Informative)

idontgno (624372) | more than 3 years ago | (#36734208)

Good Lord. Have your psychiatrist adjust your dosage.

As is the case in a conventional "fan-plus-heat-sink" CPU cooler, the heat load is placed in thermal contact with the bottom surface of an aluminum base plate that functions as a heat spreader. As in a conventional CPU cooler, this heat spreader plate is stationary. In a conventional CPU cooler, the top surface of the heat spreader base plate is populated with fins. In the air bearing heat exchanger, instead of having fins, the top of the heat spreader base plate is simply a flat surface.

The âoeheat-sink-impellerâ (the finned, rotating component) consists of a disc-shaped heat spreader populated with fins on its top surface, and functions like a hybrid of a conventional finned metal heat sink and an impeller. Air is drawn in the downward direction into the central region having no fins, and expelled in the radial direction through the dense array of fins. A high efficiency brushless motor mounted directly to the base plate is used to impart rotation (several thousand rpm) to the heat-sink-impeller structure. The bottom surface of this rotating disc-shaped heat spreader is flat, such that it can mate with the top surface of the heat spreader plate described above.

During operation, these two flat surfaces are a separated by a thin (~0.03 mm) air gap, much like the bottom surface of an air hockey puck and the top surface of an air hockey table. This air gap is a hydrodynamic gas bearing, analogous to those used to support the read/write head of computer disk drive (but with many orders of magnitude looser mechanical tolerances).

Heat flows from the stationary aluminum base plate to the rotating heat-sink-impeller through this 0.03-mm-thick circular disk of air. As shown later in Figure 18, this air-filled thermal interface has very low thermal resistance and is in no way a limiting factor to device performance; its cross sectional area is large relative to its thickness, and because the air that occupies the gap region is violently sheared between the lower surface (stationary) and the upper surface (rotating at several thousand rpm). The convective mixing provided by this shearing effect provides a several-fold increase in thermal conductivity of the air in the gap region.

TL;DR version: Stationary heat spreader surface on top of the IC. Teensy tiny air gap, small enough to permit heat transfer while functioning as an air bearing between heat spreader and... the next part, a heat-absorbing rotary impeller which pulls heat through the air gap into its fins, which are in turn cooled by air flow caused by centrifugal acceleration of the air through the rotating impeller assembly (squirrel-cage-fan style).

I'm not gonna pretend that there's no boundary-layer effect over the impeller blade surfaces, but I expect it'll be less than the effect caused by the common "push air down into the cooler and have it decelerate and turn 90 degrees to exit" cooler. Flow-through coolers would be more efficient than that, but air still has to decelerate through the cooler, whereas this impeller cooler makes the air accelerate during the cooling action. That might make a difference.

How well do bearings conduct heat?

The generic answer is "depends on thickness of air bearing surface (i.e., how big of an air gap), coverage area of bearing surface (i.e., is the heat spreader the size of the entire impeller, or just the small central portion of it), and the rotational speed of the rotating part on the other side of the gap -- moderate rotation speeds, in the 2k to 10krpm range, make the air in the gap turbulent and sheared rather than laminar, forcing mixing and heat transfer.

WTF happened to /.

Well, in this case, an actual scientific research article of relatively high coolness and technical merit leaked past the editors. I understand how this could be upsetting to most slashbots, given the novelty and rarity of this type of thing. Certainly, the average troll could confuse this with slashvertisement, except... there's no product. This is not commercially available yet.

FWIW, my advice is to let this get into manufacturing and retail channels and let the enthusiast guinea pigs try it out. Then, you might be able to cry "bullshit" without looking like a troll.

Artificial intelligent heat exchanger? (2)

maxwell demon (590494) | more than 3 years ago | (#36733796)

That's exactly what the Air Bearing Heat Exchanger, developed by Jeff Koplow of the Sandia National Laboratories, has developed.

So I get it was not Jeff Koplow who developed it, but the Air Bearing Heat Exchanger did develop it. The Air Bearing Heat Exchanger in turn was developed by Jeff Koplow.

Oh, and BTW the link was missing a PDF warning.

Re:Artificial intelligent heat exchanger? (1)

Dog-Cow (21281) | more than 3 years ago | (#36734116)

What kind of shit needs a warning about PDFs? Even iDevices can read those.

Epic (0)

Anonymous Coward | more than 3 years ago | (#36733838)

I wonder how much energy you can save spinning the whole damn PC?

Historical prototype, prior art (1)

scharkalvin (72228) | more than 3 years ago | (#36733890)

Well this idea isn't new at all. Back in the 1910's aircraft engineers were trying to produce engines that could be cooled without heavy water jackets and radiator cooling systems. Putting cooling fins around the engine cylinders and block to let the passing air cool the engine worked, but not well enough given the state of metallurgy at the time. One solution was a rotating radial engine. In this configuration the crankshaft of the engine was bolted to the firewall and the block spun around with the crankcase and cylinders. The prop was bolted to the block. These rotary engines were cooled by spinning the engine. Some compromises resulted, the oil system was a non-recycling system with some oil being burned and the rest lost with the exhaust. A vegetable based oil was used (which had a laxative effect on the pilot!). Many of the aircraft of WWI used these rotary engines, including the famous Tri-Plane of the Red Baron.

Re:Historical prototype, prior art (1)

Chrisq (894406) | more than 3 years ago | (#36734132)

A vegetable based oil was used (which had a laxative effect on the pilot!).

Or was it just coming up against the Red Barron?

Boundary Layer from Transport Phenomena (0)

Anonymous Coward | more than 3 years ago | (#36733910)

AFAIK, the boundary layer they are referring to is from the assumption that at a solid-fluid interface, there is a 'no-slip' boundary condition. This means that the velocity at the wall/surface = velocity of the fluid. This holds *relatively* true at a variety of liquid conditions, but it does not hold true in any realistic sort of way (sort of like ideal gas law versus real life). Some examples could include extremely fast flow (turbulent), hydrophobic/hydrophillic interactions at the surface, and roughness of surface to name a few. In this case, I somehow doubt that air has a no-slip boundary layer with the surface at the flowrates commonly seen in heatsinks.

I am no fluid mechanics person, so I will defer to them. But this article seemingly does not do justice to whatever science that may be at hand.

Also... "Thermal Brick Wall” that is preventing computer chips from moving beyond 3GHz" - what is this nonsense? 3 GHz+ CPUs have been around for like... years. Maybe they mean 4 GHz which is less common (yet still not unheard of).

Ferrofluidic seal (1)

Neil Boekend (1854906) | more than 3 years ago | (#36733958)

I would imagine replacing the 0.0254 mm of air with a ferrofluidic seal [wikipedia.org] would increase the efficiency even further. A chip is not damaged by a permanent magnet and since the RPM is low it will not require a very strong magnet. The seal would be a good thermal conductor (somewhere around thermal paste).

As seen on TV? (0)

Anonymous Coward | more than 3 years ago | (#36733990)

"If you call in the next 30 minutes, we'll throw in another one for free!" Was I the only one who half expected a "As Seen on TV!" badge on this product after just reading the summary? Please tone down the rhetoric if you want to be taken seriously - it makes one automatically suspicious.

welcome to http://www.ilove-shopping.org (-1)

Anonymous Coward | more than 3 years ago | (#36734036)

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I'm better than you! (0)

Anonymous Coward | more than 3 years ago | (#36734062)

This clearly doesn't work! I took a few science in classes in college, so there is no way this idiot and his 44 pages of experiments and proofs can change the opinion I developed half way through the summary! Good ol' /.

Check out Fig. 10 (2)

lee1 (219161) | more than 3 years ago | (#36734084)

I like the "protective wire mesh container". Tell me it's not an office trash can.

I didnt RTFA but.... (3, Insightful)

metalmaster (1005171) | more than 3 years ago | (#36734100)

I thought a long standing goal of PC manufacturers was to do away with moving parts. I dont think fans will go away anytime soon as long as they are cheap [newegg.com] to replace. From the comments hear I'd assume this heatsink spins on a platter essentially taking the place of the fan. What do you do when it fails? Can you replace it for less than $10?

The article answers your questions. (0)

Anonymous Coward | more than 3 years ago | (#36734144)

I scanned the article. It does answer the questions. Heat is transferred through an air cushion between a spinning and a stationary surface. This air gap is self -regulating. The motion between surfaces reduces the boundary layer thickness and its thermal resistance. Pretty cool, they used helium and nitrogen to measure the boundary layer properties. It might be better than rough heat sink surfaces because of its resistance to fouling.
I was disappointed in one aspect by the article. It mentioned possible noise reduction but with no noise measurements. They also kept mentioning 5000 rpm which suggests that the noise benefits are still elusive.

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