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The Fanless Spinning Heatsink
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!"
I think a better description would be a heatsink that is a fan or probably more accurately an impeller but without the tube enclosure.
These comments are my own and do not necessarily reflect the views or opinions of my employer or colleagues...
'sup 20721 posse
God I love hot wet pussy. Even if it doesn't have a heat sink
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.
And just how does the heat get transferred from the object needing cooling to the heat sink itself? Or does it rotate as well...?
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...
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)
But think of all the homeless Dust puppies!!!
have you no shame?
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 /.
John McAfee 'It was like that time I hired that Bangkok prostitute; to do my taxes, while I fucked my accountant'
I think my Macs have had this for a long time. I guess this is trickling down to the PC people now.
you thought wrong, they use standard box fans or squirrel cages
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.
The Tao of math: The numbers you can count are not the real numbers.
I wonder how much energy you can save spinning the whole damn PC?
Comment removed based on user account deletion
... made from the hooves of a unicorn.
Godaddy is a scam and a ripoff.
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.
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).
I would imagine replacing the 0.0254 mm of air with a ferrofluidic seal 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).
Well, I might have a way, but it only works on a semi spherical planet in a vacuum.
"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.
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LOL yes I forgot about that part
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' /.
I like the "protective wire mesh container". Tell me it's not an office trash can.
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 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?
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.
In these "old" engines, the cooling block itself did not move, rather the engine it was attached to moved. The equivalent would be for an entire PC to spin in for radiators attacked to it to be cooled. This would be highly inconvenient for any cat owners as well as make it even harder to plugin that USB cable.
MMO Quests are like orgasms:
You may solo them, I prefer them in a group.
Don't some lawn mowers have heat sinks like this that spin atop the engine?
Anyway, I'm much more interested in the air conditioner applications of this than electronics use. I like the idea of a quieter, 30% more efficient air conditioner/heat pump. Great article.
Proverbs 21:19
wonder if the barrier is caused by the constant, unidirectional flow of air from a fan?
while it's hardly an efficient/practical design, would you achieve the same efficiency if you moved a fan around the heat sink?
Also, a filter on the intake seems a simpler solution to fouling.
Soon at the heart of every computer there's a metal fan.
I tried spinning the heatsink, thermal paste flew all over the inside of the case, and the CPU still overheated.
yea filters get clogged, and I really dont by the immunity thing, yes it may not get compacted tween a fan and the top of a heat sink but it seems like the fins of this thing would be just as easy to clog since your passing dirty fluid tween small spaces
With this, it'll be smaller and lighter, can you shut down in time to avoid frying the CPU (physically)
I seem to remember Pentium 4 CPUs using a scheme like this: When the temperature exceeds one threshold, the "Thermal Monitor" puts the core to sleep for a few microseconds every microsecond. When it exceeds a higher threshold, the CPU halts.
or crashing the filesystem?
A reliable file system has to survive loss of mains power anyway.
We don't need a lot of big government creating new technology and improving our energy consumption!
Democracy Now! - your daily, uncensored, corporate-free
The heatsink + fan approach has one boundary layer on the heatsink, this approach creates two:
1. On the surface of the rotating heat sink
2. On the air cushion where the rotating heat sink "sits" on
What makes sense is to use energy efficient systems, not using any CPU-/GPU-fans and use a large and slowly rotating fan moving the air through all of the case and go for standard heatsinks on your chips. Voila: quiet, energy efficient and efficient at the same time.
This is awesome. It appears to be using similar principles and design to Tesla's turbine! (From wikipedia, which doesn't have a good picture of the innards) "The Tesla turbine is a bladeless centripetal flow turbine patented by Nikola Tesla in 1913. It is referred to as a bladeless turbine because it uses the boundary layer effect and not a fluid impinging upon the blades as in a conventional turbine"
"Sometimes a woman is a kind of religion, she can save your soul & set you free from all your sins" - Bad Examples
Just do away with the bearings required to spin the heatsink by making the CPU spin as well. That's right, I came up with it first. All licenses fees can be paid directly to me :)
In the case of an aircraft engine, the air cooled cylinders have a short thermal path to the air from the heat source. The problem with cpu cooling is mainly the long thermal path which makes it hard to get moving air down in the fins.
Finally, you might be amused to know that the lubricant (castor oil) was simply better than any mineral oil up until the 1930s. The Castrol oil company derived its name from it. And the solution of the pilots to the laxative problem was to drink whisky. It's not surprising that WW1 pilots had an operation life expectancy of a few hours.
From scarped cliff or quarried stone she cries "A thousand types are gone, I care for nothing, no not one."
.. it seems like a great invention, trully ground-breaking if it works. All we have to do now is wait for the patent wars to be over (suddenly $BigCorp and $PatentTroll "discover that this infringes on their innovations somehow and some such"), and by 2054 this will be a commonplace in cooling.
Now I wander if the guy was under contract- if he was, he will probably get nothing but his salary out of it. One of my friends is family with the guy that invented the dictionary in cellphones; but since he was under contract he got nothing more than that month's paycheck ..
The three laws of thermodynamics:(1) You can't win. (2) You can't break even. (3) You can't even quit.
That's it, really. Small IC engines are usually air cooled using a ducted fan. My rotavator has one. As I note in a post above, IC engines don't really have the problem because the path from heat to sink is short and the power density is quite low, and the main benefit of well designed fan cooling is that the cooling is even around the cylinder. The fin depth on a Honda 50cc engine is less than that on many CPU heatsinks.
From scarped cliff or quarried stone she cries "A thousand types are gone, I care for nothing, no not one."
And wouldn't the friction of the thing spinning generate heat as well? I'll admit i just looked at the pics but heatsink compound is made for heat transfer NOT lubrication so I don't see how this would be such a great improvement, not to mention having it spin right on top of the CPU would have me worried about it putting sideways pull on the pins, as anyone who has built boxes knows those pins are teeny tiny and don't take much to bend so if the lubricant you used started to get sticky I could see this thing slowly but surely causing problems with the pins.
So unless someone can explain how they've done away with friction and the risk of stress on the pins I have to vote meh. And while this might have been helpful in the days of the P4, aka space heater in a box, at least with modern CPUs if anything power has been going pretty steadily downward. I know I have to slam the new AMD quads pretty damned hard to get the fan to crank up and even then they rarely reach above 130f, and that is with all four cores pegged. For day to day usage they tend to stay like mine is now at 94f with the case fan being the only real fan noise.
ACs don't waste your time replying, your posts are never seen by me.
It does look like a very interesting development. But I do wonder how well that critical air bearing gap will hold up over the life of the product as you won't be able to seal it like you do with hard disks. A 0.03mm air gap is a very fine tolerance for machining and thermal expansion of the base material could have a significant effect, particularly as both the heat load and the cooling capacity won't be perfectly even over the entire base.
The other thing that struck me was that the location of the motor will inevitably limit cooling capacity in the very centre of the heatsink. The experimental data was gathered using heaters spread across the base which is a reasonable model for HVAC applications. But the heat generated by a processor is much more concentrated in one small spot and I'd like to see some numbers for how well this heatsink copes with that.
It appears to be using similar principles and design to Tesla's turbine!
No, that's quite different. This thing has blades. It's a centrifugal pump for air.
I'll believe that when I see some empirical evidence. Seems like they've just said "well it spins; of course it won't get dust." My current fan spins, and the fanblade is covered with the stuff. Static attraction overcomes the motion easily.
"The Sandia Cooler may also be the technology that smashes down the “Thermal Brick Wall” that is preventing computer chips from moving beyond 3GHz."
Sorry, we've got CPUs hitting 4+ GHz on stock air cooling without your specialized heatsink. Your thermal brick wall doesn't exist and hasn't for quite some time.
We also have mesophase carbon pitch heatsinks hitting 1,000wmk, 4x better than copper.
Fire the article writer, as it's clear they've had their head in the tech sand of yesteryear.
Still waiting on Serviscope_minor to wake up to fucking reality and realize that Jessica Price isn't going to fuck him.
From TFA, highlighted for your convenience...
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.
The effect of the Sandia device is not to eliminate the boundary layer, as the article says, but to make it much thinner, as the PDF says. The thermal resistance of the boundary layer is approximately proportional to its thickness, so the heat transfer goes up by the same ratio. That moves the heat into the air between the impeller fins, which then proceeds to carry it overboard.
That's what is so impressive about this work. A spinning, finned heat sink isn't new. Combining it with a thermally efficient coupling to a stationary heat source is.
They came up with a helical groove design to maximize the radiating surface while also moving some air to create circulation. The dust free radiating surface heat exchange efficiency was so high, they needed to move very little air. So the final design has large moving surfaces with small grooves in them to move a little air. That is all.
The moving helical groove fan can not be scraping along the top of the IC chip. There is a gap. And if that gap is not well protected from dust, it will get there. May be they can come up with a seal and a fluid coupling? I am not sure.
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
The bearing between the fan and the plate is a very small air gap. Because it's small, and because it's constantly being churned around, it's thermal resistance is low.
Because the movement fan part destroys the normal zone of still air around radiator fins it dissipates heat more quickly and efficiently.
I know its said a lot and should be common knowledge but I think it pays to stress it more strongly on occasion. This seems like an ideal time, READ THE FUCKING ARTICLE.
Several posts now, numerous mod points and dozens of follow ups all frankly making complete asses of themselves ironically complaining about how the IQ of /. has dropped while they make angry complaints and rants about the story that are fully addressed in the documentation.
and if you think that the fact that the summary screwed up is still a good sign of /. intelligence drop then you really need to look right back in the archives because bad summaries have been around on /. and virtually everywhere else pretty much from the beginning. Unsurprisingly the people posting the stories dont have total knowledge of the often fairly complex material posted and they screw it up good and proper on occasion. Which is probably why you should be judging the posts on the documents they link to and not the quickly thrown together summary by an admitted layman. Anything else is ironically a really stupid thing to do.
READ THE FUCKING ARTICLE.
(and no this doesnt mean the documentation is flawless but make commentary on that, not the summary, it will raise that intelligence level a lot of you are so eager to whine about.)
Anyone with an old oscillating fan can tell you that just because it moves doesn't make it 'immune' to dust. It may resist heavier buildup but it will end up just as coated eventually.
When a fan rotates, the air right on the blades doesn't move -- that's why fans get dirty over time, as dust gets caught in that region of barely moving air.
I'm not sure I see a big difference here between a heatsink that moves through air and a heatsink that has air move over it.
Man that is a long article. I didn't read every word, I skimmed it looking for what's important to most PC builders: the damn thing's thermal performance.
There are a lot of graphs, but I kept looking and couldn't find one that simply showed how well it performed in cooling compared to other devices.
Finally I found a tiny little graphic showing the prototype in a list with other HSFs. The result? I tiny improvement over most of the devices it was compared to. However, the article indicates that the first prototype had a sub-optimal design and they anticipate much greater improvements in version 2.
Maybe that's why they wrote this hugely dense report instead of just releasing a brief statement saying "we've kicked the ass of other HSFs". Maybe if their next version shows a significant improvement they will be able to do it, and then I'll give a crap.
The exception to this rule is lap top computers, where available electrical power is extremely limited. In this special case, CPU clock speeds and fan rotor speeds are reduced to conserve power, albeit at the expense of CPU performance. At these low fan speeds the residence time of air in the heat exchanger is greatly extended, resulting in much higher exhaust air temperatures.
I will create a sig when innovation restarts in the U.S.
It's even intrinsically immune to the build up of dust and detritus!
I seriously doubt that. Anyone who has repairs computers can tell you that even rapidly spinning fan blades can accumulate a thick coating of dust. Since this new device spins at "low and very quiet speeds", it's probably even less immune to dust.
Seems similar to an idea I had when I joking thought of spinning the CPU instead of having a fan. Instead of contacts maybe use electromagnetic or photons to connect to the CPU. Then there would be no air barrier to deal with.
Any move part will break is subject to failure.
Because I refuse to read the article I will make some snap judgements. It is uses a motor then the spinning process is subject to failure. They need a non-mechanical means to spin the heat sink - for example user the heat itself to cause the whole assembly to rotate (spin).
If it's anything like the fans I see, the blades end up dust coated but not dust choked. Dust beyond a certain level gets flung/blown away.
Whereas conventional heatsinks can end up dust choked.
Wow. This is something I have been doing on and off for years. It actually does a good job of keeping things cool... although my heatsinks were more standard shaped instead of shaped like a fan.
My first thought looking at the linked paper was, "January 2010? Why hasn't this been all over the place if the results are so promising?"
But there could be lots of reasons for that. Just sort of popped out.
Another question that comes up is overall system efficiency. One advantage of the current fan + heat sink paradigm is that in addition to moving air across the heat sink, which is not terribly efficient, the fan also serves to mix the heated air around the heat sink with the larger reservoir of surrounding air. They don't really directly discuss it, but my impression is that their design would result in very little large-scale mixing; one of the efficiency advantages is that they aren't moving large amounts of air around. It seems that in a setting like a CPU cooler this might be a non-issue, as you would still presumably be using case fans to move air through the case (exchanging the reservoir); but in something like an air conditioning unit, it seems like it would become limited by convection for larger scale heat transfer - or require an external fan for air exchange.
Basically, my concern is that while this method might be very efficient in moving heat from the base plate to the air in the immediate vicinity, you would then have the problem of heat building up around it. Perhaps not an issue where you have a small-scale device open to a large, room-temperature environment (or where you already have something in place to move air around, like a computer case), but it seems like it could be an issue moving to something like a residential air conditioner.
Still, it appears to eliminate the boundary layer problem, so you could use a pretty efficient, large, slow-moving fan for air exchange - so probably more efficient than blowing high-speed air across a heat sink, but something that would need to be considered in a full implementation.
immune to dust
Let's just start with "NO" and go from there. Unless you've got a high grade low micron filter on the intake, air circulation is going to lead to dust collection. And then you have filters to replace. Neither solution has any business calling itself "immune" to the problem.
The article reads like a used car salesman trying to sell you a car based on all the wonderful "win/win" features it has, trying to ply a "reality distortion field" as the popular saying goes.
And unless it's using a sealed fluid bearing, that is going to get fouled eventually by dust too. That's what tends to take down cpu fans. Considering the comparatively low torque of such a system, it should come to a stop a lot sooner too.
And I never did see any justification on this "boundary layer" theory, and as to why the lack of a fan magically makes it disappear.
I work for the Department of Redundancy Department.
All of the gaming enthusiasts complaining that this is impractical for heatsink technology because it's too expensive, or that a simply larger passive heatsink could do just as well, are missing the whole point of this kind of research. Engineering is an optimization problem, and keeping the size/weight parameters the same while increasing efficiency is a victory any way you cut it. Sandia does a lot of weapons/aerospace research, so this may have immediate applications for them in computing environments where size/weight constraints are the limiting factor.
Yes but considering that the purpose of a heat sync is to dissipate heat rather than blow air, the point it mute. If the blades get coated, then heat dissipation is still reduced. I'm not saying it's not a better idea than current implementations, but they should at least be a bit realistic in their claims.
Not understanding why it's supposedly immune to gunk? From what I've seen with regular fans, the finer dust tends to cake on to the blades.... this design has really small gaps between the blades, and relies on the small gap between the blade assembly and the exchange plate.....Wouldn't it get clogged and gummed up the same way conventional fans do? It's not going to be the only fan in the system, other fans will be blowing gunk up against it from the side typically, so that would probably eventually force the dust into the gap. Would be more resistant to stiction though....if they make them from aluminum that is....a lot of fans today fail because there is too much stress on the plastic after the gunk builds up.
The Farnsworth Heatsink is much better. The heatsink stays still while the universe spins around it.
If only I had mod points today. Great succinct description.
It is reduced but I'd wager that even coated fan blades are more efficient than a solid block of non heat conducting material, i.e. the dust caked onto the now solid heat sink. There's 'zero' airflow over the surface if you can't get to the surface.
The fans are still pushing air over the surface.
People in cars cause accidents....accidents in cars cause people
you dont understand. they go with my monster cables.
Drop the "micro" and what you've said should be very obvious.
I realized what I had written after I had clicked Submit. On the actual P4, the Thermal Monitor sleeps are as long as the wakes. I apologize for any confusion.
Indeed - an even better description would be a 'heat-sink-impeller', a term used many times in the paper itself !
Describing this device as 'fanless' isn't very informative since anything that either doesn't contain or isn't a fan is by definition fanless....
And I never did see any justification on this "boundary layer" theory, and as to why the lack of a fan magically makes it disappear.
It's basic aerodynamic theory.
I wonder how jostling of the PC case might affect this 'bearing'? Is it possible that the spinning disc would then impact the static metal base plate?
Seems like this concept would already have been dealt with via spinning hard disk platters, but those don't weigh nearly as much as a heat sink and are segmented out specially with shock absorbers in the HD enclosure.
People in cars cause accidents....accidents in cars cause people
Rather than a narrow air gap which might be delicate, I wonder if filling the space between the stationary and rotating parts of the heat sink with oil or even water would be better. Air has a thermal conductivity of .024. Oil and water have thermal conductivities roughly an order of magnitude greater. An objection to this idea would be the need for a low friction seal around the circumference of the unit but perhaps such low friction seals exist.
That "boundary layer" theory is well justified by models and experiments. The lack of a fan does not make it disapear, but rotating the heat sink does make it smaller.
About dust, it only accumulates over a hight speed rotating surface (where the air speed is increasing) up to a certain amount. That amount is certainly way lower than the dust that accumulates at a static place where the air speed drops. Immune do dust is a justfied simplification, altough a bit over confident.
Also, I completely agree with your point about the dust accumulating at the gap. That device won't last for long at the real world.
Rethinking email
Agreed - after reading the article it seems more that the heatsink is now a fan as well. And after working with machines that use air bearings, they work great until there's a wobble....
Does it work when it's vertical (i.e. axis of rotation is horizontal)? It's been a long, long time since my desktop was actually on my desk rather than stood beside it.
Disclaimer: I only skimmed the PDF, I didn't RTFA at all.
If God forks the Universe every time you roll a die, he'd better have a damned good memory.
So there is a small air gap between the CPU and Cooler - what happens in shipping? I would be interested to see the results of these test...
#1. No didn't RTFA.
I can just see a 500g serrated chunk of copper spinning at 2500 RPM inside a framework of delicate electronics!
I hope you mount it exactly right, be a shame if that thing got the speed wobbles and physically destroys everything in your PC case!
I wonder how TFA might have covered this subject...
That's all well and good but what do you do to get rid of the heat in the fluid besides run it through a radiator with a fan on it? But wait! If we use one of these spinning heat sinks on the other end of the liquid cooling system, it will be more efficient. But then it's still more efficient to use liquid so let's immerse that one. Crap. We need another radiator. Hey! Let's use one of those spinning heat sinks...
iMacs and MacBooks use radial fans and you could say this is a radial fan too. However in this case the heatsink is it self the fan while macs use the normal fan with separate heatsink construction. BTW there are also PC notebooks and desktops with radial fans. Radial fans are in general quieter and are much better at building pressure so they are much better at pushing air through a heatsink. However they are more expensive.
I only had time to skim the article but it's a very interesting approach. I can see the air conditioning version optimizing the fan shape so that it can be use as the blower inside and outside to drive the exhaust away from the building. Using the external heat exchanger to as a pool pump could reduce the energy needed to heat the pool. Of course in warm climates, you would probably send the pool water back through a fountain to cool it off.
I guess I'm the stupid one here, but I don't understand the basic premise. Can someone please explain exactly what this "boundary layer" of motionless air is on a regular heatsink/fan? Why/how does it form and exactly how big of a problem is it really? I am just not understanding how there can be any motionless air unless there are some eddies formed by the fins or some such. Help! Thanks.
yup.
First off, it's not true that the boundary layer is immovable. The molecules within it are moving at hundreds of miles an hour. They aren't sticking to the metal and preventing heat flow. They're hitting the metal, picking up momentum from the atoms in the metal, and rebounding at higher speed. I.e., taking heat away from it. (Look up "kinetic theory of gases" in any elementary-school physics text.) If you blow on it, you will move those molecules out of the way, and replace them with cooler ones, allowing heat to flow from the metal faster. (ibid.)
Second, making the heat-sink move is no different from blowing air at it. Because that's all it's doing. It's just doing it the hard way. Like driving to work by moving the road under your car instead of your car over the road*.
Third, there's no way that you're going to get as good a conduction of heat from the substrate to the heat sink if the heat sink has to be on a moving bearing. The bearing surface will be smaller than you could get from a static surface, and friction in the bearing, which can't be eliminated, will actually add heat, which you will slow transfer from the substrate.
Fourth, it's not true that you can't make heat sinks "immune to dust". You just have to design them not to have eddies when the fan is on.
This whole topic is teh bollocks.
* - my superpower is thinking up car analogies.
jostling of the PC case
The Bastard Operator From Hell would like a word with you.
I assume you mean in a mobile application, and I think that the physics involved would require so much force for the air cushion to be compressed that the rest of the computer might be a goner.
What I'm more concerned with is if this fan always has to be mounted horizontally, and if I'll need to lay my ATX tower flat or manually set the fan spinning to make it overcome friction.
All rites reversed 2010
What do you do when it fails? Can you replace it for less than $10?
Obviously not. The replacement cost seems be closer to the cost of the full heat sink. If prices drop to realistic rates, it will probably be similar to today's after-market heatsinks (~ $30 - $50), maybe a little more. The motor will need to be more sophisticated (high RPM), but it won't need heat pipes.
You're right that it causes an issue, but a very minor one. Most heatsinks sold today have a built-in fan which is not designed to be replaceable.
As an aside, this white paper is old. It dates to Jan 2010. have there been any recent developments?
(ps hear != here)
I won't join Slashcott. OTOH, If Beta goes live, I just won't be back until it's fixed. Sorry Dice.
I thought CoolChip was already selling a commercial product that did this.
>Koplow estimates that the total US electricity consumption could drop by 7%
It is also wrong. Due to Jevons paradox we would just find another way to spend the energy we gain.
You realize air is a fluid, right?
Power hungry PCI-e graphics cards have a very similar fan to move air (e.g. http://www.bit-tech.net/hardware/2011/03/08/amd-radeon-hd-6990-review/1).
Use one of these "fan heat sinks" in place of that fan : i.e. add a shroud so air is sucked in the middle, and have the air from the edges vent to the outside of the case.
Easily solvable (search on plenums in the article) - article assumes this is obvious enough that it doesn't need in depth discussion or explaining?
Yes. You realize the post I responded to specifically called out water or oil to improve efficiency, right?
Rather than spell out "oil or water" each time, I saved a few keystrokes by just typing "fluid". It's called context. Learn it. Love it. Live it.
Air bearings are very stiff. Read the article for details, but the shock absorbers (ie. rubber mounts) on HD's are not what keep the heads from hitting (for most shocks). The air-bearing is.
Along with the greater weight of this heatsink design is the greater area of the air bearing. More area == more stiffness. A tiny bit of reading on fluid bearings (static or dynamic) convince me that a decently designed air-bearing will be more than enough to prevent surface contact during movement/shock. And as pointed out in the article, incidental contact is a non-issue for heatsinks (whereas you may not want the same to happen to your HD's).
Those of you following MIT's Clean Energy Prize back in May will no doubt recall this ground-breaking technology being advanced by big winners, "CoolChip Technologies."
Check out this YouTube video: http://www.youtube.com/watch?v=zAf_p-7cTDo . You can see Sandia's graphics and photos up on the screen behind the winners at 2:45 (where the winner's talking up "our unique, patented design") and a photo of the Sandia prototype at 3:55. No mention of Sandia, though, and no other images of "their" cooler. Just unattributed reprints of Sandia graphics.
Here they are accepting the big check http://www.boston.com/business/ticker/2011/05/09/mitcomp.JPG (Lookit how big it is! Wow! That's big!) standing next to the President of the Massachusetts Institute of Technology (Big! Big! Big!) holding onto a reverse-engineered Sandia Cooler impeller.
It's ironic, of course, because to enter the contest, they signed a form with these terms and conditions on it: http://cep-community.mit.edu/info/termsOfUse.html, including item 3, a statement of originality, that they warrant that they invented it or have a proper license to use the technology. Pity they didn't invent it and don't have, y'know, an actual license or anything... They're hoping to get one, maybe, someday: https://www.fbo.gov/index?s=opportunity&mode=form&id=1008179315e9f62949210bd6b07b6889&tab=ivl&tabmode=list , and after all, it's the thought that counts...
They've won $230,000 in a business plan competition for technology they can't legally bring to market, but MIT/Sloan thinks it's no big deal...just as long as it stays under the rug. Keep your eye on the important points: Signed a statement saying they have a license. Have no license. Call this "our unique, patented design." Beat non-MIT teams that played by the rules. MIT knows, but isn't doing anything about it. You can't say they don't take care of their own...