"Fanless" spinning CPU cooler prototype from Sandia National Laboratories

BoomerD

No Lifer
Feb 26, 2006
63,428
11,757
136
So it's not really "fanless," the heatsink becomes the fan and does away with a separate fan for the unit...

good idea...if it really works.
 

Raswan

Senior member
Jan 29, 2010
702
6
81
I'll call BS. Unless that thing spins a thousand times per second, which I can't envision working while maintaining solid contact with the cpu surface, no way it's moving the heat away fast enough to dissipate. I say it's a gimmick.
 

Termie

Diamond Member
Aug 17, 2005
7,949
48
91
www.techbuyersguru.com
How does a rotating heat-sink stay in contact with the hot cpu surface?

I don't think it actually is in contact - it seems to operate like an impeller fan (similar to AMD GPU reference coolers), but the impeller is mounted directly above the metal base plate (at a very tight tolerance).

So it's not really "fanless," the heatsink becomes the fan and does away with a separate fan for the unit...

good idea...if it really works.

Right - it actually has a fan that is built into the heatsink. It just doesn't look like the fans we're used to for CPU heatsinks. I'll change the title to put "fanless" in quotes.
 

JTsyo

Lifer
Nov 18, 2007
11,774
919
126
Looking at the heat thermal pic they have up, there's the 1 mil air gap and the temperature on the heat sink is close to the stationary plate. I guess convention gets the heat across.
 

bridito

Senior member
Jun 2, 2011
350
0
0
I read through the PDF but was completely confused until I got to the equations at the bottom of page 23. They clarified everything! Check them and see!
 

Michael Meio

Member
Jul 2, 2011
48
0
0
It seems that under very specific circumstances, something occurs when there is a 0.001 gap between a heat source and a rotary element that in presence of little air flow, exchanges more heat than everything currently available for us mortals, including direct contact, thermal compounds, flattened pipes, etc. It's hard for me to assume that a gap will do better transfer than direct contact.. Still, I know little about thermodynamics and this marvelous effect, but hey!, there is the wing ground effect in aerodynamics, so I don't know.

Another thing I don't buy is the claim that it's dust free. Well, in the lab, of course!....w.....t.....f.....??? It's air!, the normal kind.. dust is embedded in it. Now, on Fig.4, shows a conventional heatsink and fan and it says that despite of both being in the same environment, the fan is practically dustless, while the heatsink is almost invisible for it's covered in dust. OMG! of course!.. well, NO! the air just happens to contain dust particles that pile up with the help of static derived from friction until they reach the heatsink's fin separation. The fan's blades are just too far apart for them to suffer the same consequence. This is a total nonsense and usually makes science people angry, so... don't! The dust will pile up eventually. Such comparisons and claims belong to TV infomercials.


Now, what exactly is 0.001 in?

25.4 µm — 1/1000 inch, commonly referred to as 1 mil in the U.S. and 1 thou in the UK

99 µm — average width of human hair (ranges from 18 to 180 µm).

It's kinda hard to find a cheap motor that presents and maintains such axial tolerances, so the spinning thing must be mounted on something quite special and no way cheapo. But what this really means is that the heatsink in contact with the CPU and the structure that supports the motor with the spinning element that floats at 0.001 in gap must be quite precise.. and that gap of .001, how do you keep it when heat shows up?.. things get fat while becoming hot!, another specialty here, no way cheapo. But they found a way around this:

"The prototype device is configured as a static (externally pressurized) thrust bearing. In real world thermal management applications such an externally pressurized air bearing would be replaced by a hydrodynamic (self-pressurizing) air bearing,..."

and then:

"...The gas delivery manifold is equipped with a manual three way value through which it can be connected to a source of compressed gas, a vacuum pump, or neither (blocked off). In turn, the gas delivery line has second three-way valve to select either nitrogen or helium, which is necessary for determination of the air gap thermal resistance."

Later on:

"The use of dry nitrogen, rather than air, is an experimental convenience. As shown in Appendix B, the thermal conductivities air and nitrogen differ by less than 1%..."

An experimental convenience.. How can Nitro or helium be more convenient than simple pressurized dried air? And if this is such axiom, why bother to state it?.. kinda fishy

Nitrogen.. helium.. valves.. externally pressurized air bearing replaced by a hydrodynamic...... Can we use simple air, instead? like for a change?. Where is the pressure liberated? at the vortex?.. that sounds like forced air cooling to me which happens to be helped by pressure gas heat exchange.

Anyway, someone in a far east country already saw this and should be getting the assembly line ready... we'll see.
 

Tsavo

Platinum Member
Sep 29, 2009
2,645
37
91
Cool idea.

Spins at 5k RPM, this thing will collect fingers though.
 

Mark R

Diamond Member
Oct 9, 1999
8,513
14
81
How does a rotating heat-sink stay in contact with the hot cpu surface?

It doesn't need to be in contact. It floats on an exceedingly narrow cushion of air (produced by the spinning blades).

Because the air cushion is violently stirred up by the spinning heatsink, it has excellent thermal properties, roughly comparable to thermal pastes.
 

Mark R

Diamond Member
Oct 9, 1999
8,513
14
81
Another thing I don't buy is the claim that it's dust free. Well, in the lab, of course!....w.....t.....f.....??? It's air!, the normal kind.. dust is embedded in it. Now, on Fig.4, shows a conventional heatsink and fan and it says that despite of both being in the same environment, the fan is practically dustless, while the heatsink is almost invisible for it's covered in dust. OMG! of course!.. well, NO! the air just happens to contain dust particles that pile up with the help of static derived from friction until they reach the heatsink's fin separation. The fan's blades are just too far apart for them to suffer the same consequence. This is a total nonsense and usually makes science people angry, so... don't! The dust will pile up eventually. Such comparisons and claims belong to TV infomercials.

But that's the thing, that's probably not the mechanism of fouling. The fouling occurs at the edge of the finned heatsink, so is probably related to the sudden turbulence where the air flow enters the finned area. Anyway, they do go on to discuss some crude tests of fouling, where they suggest that it is essentially zero in room air.

"The use of dry nitrogen, rather than air, is an experimental convenience. As shown in Appendix B, the thermal conductivities air and nitrogen differ by less than 1%..."

An experimental convenience.. How can Nitro or helium be more convenient than simple pressurized dried air? And if this is such axiom, why bother to state it?.. kinda fishy

Nitrogen.. helium.. valves.. externally pressurized air bearing replaced by a hydrodynamic...... Can we use simple air, instead? like for a change?. Where is the pressure liberated? at the vortex?.. that sounds like forced air cooling to me which happens to be helped by pressure gas heat exchange.

It depends on the site. Some labs have ample supplies of gas cylinders, or even gas on tap - whereas air compressors, especially ones with dryers, might not be part of their standard equipment. Far better to use a few bottles of purified gas which is consistent quality, rather than try to use a cheap compressor.

Similarly, the air bearing doesn't seem to be the site of heat dissipation - their IR pictures show that, and temperature measurements show that. It's clearly the fins that are dissipating the heat.
 

bridito

Senior member
Jun 2, 2011
350
0
0
I had construction going on next door a couple of summers ago and I'd have to wipe every surface at least every couple of days from the thick layer of dust coming in through the windows. I can assure you some of those particles were larger than .0001 in. Just one of them jammed up in the "cushion" area and we have a real problem that is likely going to fry a CPU. Besides, with the manufacturing tolerances and types of materials required, this thing is likely to cost more than a top end CPU. I'm putting this in the pie in the sky file for now at least.
 

Michael Meio

Member
Jul 2, 2011
48
0
0
Correct me if I'm wrong... but after double-checking (since there is not a clear section of the device), it appears that the fins are attached to a plate at their bottom and the cushion and .001 gap is below that plate. Essentially, the fins are not part of the gap / cushion, as I see it.

If that's the case, the cushion or gap is free from air flow which will solve the dust problem within.

I tried to picture this device without the gap, as if the whole thing rotated (heat source + plate + heat sink impeller).. Just imagine a spinning fin array shaped as pictured with a lighted candle at the bottom, below the plate. In which case, there will be absolutely no heat loss between the source and the fins, or in other words, the fins become the source of heat themselves.

I honestly doubt the surface extension and air flow will be enough (even at 5000 + RPM) to get rid of it all. The gap and it's thickness are a problem which can be solved mechanically with the adequate parts and assembly. but the heat exchange between the fins and ambient is worrying..

Now picture it different: Let's put my imaginary fins static and just add a blower from the top (be it Nitro, Helium, Air, etc.. lol!) just blow air from the top. It will be no different from any conventional setup principle-wise. And that's the reason why I probably don't understand hence my skepticism. As I said before: Unless there is some marvelous effect happening at the gap that helps to get rid of heat (not to isolate it! to dissipate it), there is no reason to assume it will work better than a piped heatsink / fan setup.

The gap is distracting, so I decided to ignore it since in is located between two plates and not between the fins and a plate. If the fins do the job, I need a simpler explanation of how the heat disappears from the device and why it needs to spin after all. Which would be a totally different approach.

Maybe this is a question of the fan blades, their material and the effect on them while spinning, how the air beats against them and finally, how the rotation affects the heat exchange differently than just blowing air through. Why can't it be replaced by twisted fins on a piped heatsink and just blow through. Mehh.. I guess we need more air then. Like 5k rpm and 500CFM I know little about numbers.
 

zephyrprime

Diamond Member
Feb 18, 2001
7,512
2
81
I think you're really over thinking this Michael. The thing is just a heatsink and fan combined into one unit. It has smalls gains in efficiency due to not having a separate fan. In a conventional setup, you expend energy to move air through the fan and the fan also has to produce enough excess kinetic energy in the air to push it through the heatsink (it has to produce enough power to ). In this design, you only have to spend energy doing one of those things rather than both of those things. Also, it's common to have a lot of dead air and inefficient airflow in ordinary cooling designs and this is reduced in this design because the heat dissipation surface is integrated with the fan.

However, I see some problems in this design. It's worrying that such a high RPM is apparently needed (5000RPM). Kinetic energy increases quadratically with speed so having a high rpm would make the device more power hungry than lower rpm designs. Also, this device may have problems scaling to larger devices. The cooling fins in this design cannot be too tall because the higher parts of the blades will not be hot. So the only way to scale this device up in size would be to have lots of parallel devices which is a problem due to high part count and costs.

I agree with you that the air gap thing is a distraction is merely a mechanical neccessity of the design rather than the source of it's improved cooling.
 
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Kyanzes

Golden Member
Aug 26, 2005
1,082
0
76
When the fan hits 88 revs a sec, the excess heat is sent to the future via an Einstein-Rosen Bridge. Since they have an ice age in the future, the excess heat is sucked in from the past (our present) and released into the atmosphere in the future. In time it will have a palpable effect and reverse the ice age. A slow process but they are getting there.

Some say the whole ice age started when unknown individuals started to suck away heat from our world, sometime around now. The exact method or the why is not known. Anyways, let's help our descendants in the future to heat up their world once again.
 

aigomorla

CPU, Cases&Cooling Mod PC Gaming Mod Elite Member
Super Moderator
Sep 28, 2005
20,882
3,230
126
This design is so cool, however i fail to see how it will work unless ur base is insane.
And im talking about a Carbon nanotube / Graphitine type of base with the most insane thermal conductivity you can possibly imagine.


If you guys ask me, i think in about 10 yrs PC's will have a Pony tail coming out of the rear 120mm fan hole. (kinda like a fiber optic lamp only used for heat)

This Pony tail will be composed of carbon nanotube type material, and heat will be exchanged via tail instead of fan.

This is all speculation, but this is how i see PC's evolving in cooling.
 
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Modelworks

Lifer
Feb 22, 2007
16,240
7
76
If you could miniaturize a sterling engine you could easily power a fan from it using only the heat the cpu produces.
 

Modelworks

Lifer
Feb 22, 2007
16,240
7
76
I'll call BS. Unless that thing spins a thousand times per second, which I can't envision working while maintaining solid contact with the cpu surface, no way it's moving the heat away fast enough to dissipate. I say it's a gimmick.

This is Sandia Labs they don't do gimmicks. If they say it works, it works.
The boundary layer is the key to the design. When you blow air perpendicular to a surface like a lot of heat sink designs do you create standing waves. Areas of air that do not move heat because the air is hitting the surface and fighting against the air that is coming into the heat sink from the fan . If you rotate the heat sink like in this design then the heat sink creates airflow that is flowing with the fins of the sink and not creating those waves that fight the cooling.

You can get the same effect now by using a heat sink that only allows air to flow parallel to the heat sink. Designs like these would give you the same end result as the sandia version but would gather much more dust.

One with parallel air flow, what you want:
http://www.newegg.com/Product/Produc...82E16835233029

Bad design with perpendicular air flow:
http://www.newegg.com/Product/Produc...82E16835106606
 

killster1

Banned
Mar 15, 2007
6,208
475
126
Well i dont know how long the motor will last, most fans seem to last veyr long time so i imagine it will last few years but if it doesnt prob will have to throw away the whole heatsink, love the idea. but me personally i dont care about a little noise
 

EarthwormJim

Diamond Member
Oct 15, 2003
3,239
0
76
Another thing I don't buy is the claim that it's dust free. Well, in the lab, of course!....w.....t.....f.....??? It's air!, the normal kind.. dust is embedded in it. Now, on Fig.4, shows a conventional heatsink and fan and it says that despite of both being in the same environment, the fan is practically dustless, while the heatsink is almost invisible for it's covered in dust. OMG! of course!.. well, NO! the air just happens to contain dust particles that pile up with the help of static derived from friction until they reach the heatsink's fin separation. The fan's blades are just too far apart for them to suffer the same consequence. This is a total nonsense and usually makes science people angry, so... don't! The dust will pile up eventually. Such comparisons and claims belong to TV infomercials.

It's kinda hard to find a cheap motor that presents and maintains such axial tolerances, so the spinning thing must be mounted on something quite special and no way cheapo. But what this really means is that the heatsink in contact with the CPU and the structure that supports the motor with the spinning element that floats at 0.001 in gap must be quite precise.. and that gap of .001, how do you keep it when heat shows up?.. things get fat while becoming hot!, another specialty here, no way cheapo. But they found a way around this:

I don't know if this is your experience, however my heatsink/radiator fans are just about always spotless on the fan blades, while my heatsink fins are always covered in dust. The reason being one is a static part, the other is a moving part. Since the whole thing moves, it will "shed" most of the dust that would normally cling to it just like how fan blades do.

The turbulence created by the spinning heatsink, and pressure changes as the distances between the plates change, in the small air gap could also be what helps to maintain that very same air gap. Sort of like how hard drives keep the drive head suspended above the platters (*edit* just noticed they said that in the paper).


I wish they had provided noise data results. Low thermal resistivity is nice, however if it requires loud operation, I don't see this being practical. Especially when they stated in the paper one reason why AC's and Heat Pumps are being held back in efficiency is simply because of fan noise.
 
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Meghan54

Lifer
Oct 18, 2009
11,573
5,096
136
I don't know if this is your experience, however my heatsink/radiator fans are just about always spotless on the fan blades, while my heatsink fins are always covered in dust. The reason being one is a static part, the other is a moving part. Since the whole thing moves, it will "shed" most of the dust that would normally cling to it just like how fan blades do.



Absolutely not the typical experience. Usually, the leading edge of a spinning fan does accumulate dust.....computer fans, ceiling fans...you name it.
 

EarthwormJim

Diamond Member
Oct 15, 2003
3,239
0
76
Absolutely not the typical experience. Usually, the leading edge of a spinning fan does accumulate dust.....computer fans, ceiling fans...you name it.

I guess my radiator is acting as an air filter, my fans are arranged in a pull configuration.
 

Michael Meio

Member
Jul 2, 2011
48
0
0
I think you're really over thinking this Michael. The thing is just a heatsink and fan combined into one unit. It has smalls gains in efficiency due to not having a separate fan. In a conventional setup, you expend energy to move air through the fan and the fan also has to produce enough excess kinetic energy in the air to push it through the heatsink (it has to produce enough power to ). In this design, you only have to spend energy doing one of those things rather than both of those things. Also, it's common to have a lot of dead air and inefficient airflow in ordinary cooling designs and this is reduced in this design because the heat dissipation surface is integrated with the fan.

I agree with you that the air gap thing is a distraction is merely a mechanical neccessity of the design rather than the source of it's improved cooling.

Perhaps you're right and there is less energy expenditure to achieve the claimed results compared to a classic setup. I had some extra time to check out bibliography. I found that some research shows it is possible for such setup to work as claimed.

Now, somewhere out there, there is a similar setup which doesn't have the .001 in gap but rather a sort of ferrofluid bearing consisting of alum oxide mixed with some oil (i guess). In this case, the fluid is in direct contact with the cpu shield which is contained under a skirt that carries the heat. This way, the gap can be way bigger and doesn't need to be as demanding.

Putting that aside, Sandia's approach is a fan design to dissipate it's own heat. The problems remain: 5k RPM, gap preservation, durability, stability, etc. It's complicated to hold this thing while spinning/vibrating at 5k RPM (while preserving the gap) for long periods of time.. like years.. and it's apparent that it wouldn't perform as well at lower speeds. In the end, these 5k rpm and the cfm displacement it generates could (maybe) get similar results if used on a classic setup with some tweaks like special materials as someone mentioned.
 
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