Sandia-designed CPU cooler lacks fan, rotates heatsink instead

[Solus Corvus]

No, that's a logical fallacy. "It will only consume extra power" does not go hand-in-hand with "consume less power". At best you are going for a long-term near-equality. Also, as pointed out previously, the HS will at the very least have more friction and must therefore require more energy. There is simply no avoiding it. Finally, rotating at a few thousand RPM means that their goal is to use at least 2k rpm... that's a lot more RPM than most fans have, a ridiculous amount more if they're looking at 3k+.


As well, I see that picture includes an AIR GAP between the thin conductive base and the actual heatsinks. For very good reasons good coolers do NOT have air gaps of any size, but because microscopic air gaps do exist we use thermal paste. You want to see the absolute best-case scenario for this design? Go scrape the thermal paste off your heatsink and compare its performance. Except this will perform worse because the gap has to be large enough to allow a sufficiently large gap for rotation and wobble.

Oh, plus now if you're working on a server that's heating up because a motor went out you can't just replace a fan while leaving the thing on, you need to take the whole server down so you can manually and annoyingly replace the heatsink. And these motors will be more likely to fail because they're going much faster with a heavier load...


No, no... this whole thing is a horrible idea. A 100% bad idea.

Thanks for coming out swinging. Read the whitepaper, because a quick skim has already shown me several errors in your logic.

I reject your premise that there will be inherently more friction than in a fan motor. I also reject the premise that the air gap in this device is exactly the same as a static air gap. The gap is there so air under pressure can be injected into the gap as an air bearing. Air is significantly less viscous than oil in a ball or sleeve bearing so despite the larger bearing surface it is not immediately obvious which has less friction. That would depend on the size of the air gap the pressure of the incoming air versus the clearance of the sleeve bearing, size of the ball bearings, viscosity of the lubricant, etc. And while I feel it is counterintuitive that air would be a good conductor it would be under pressure and in dynamic flow both because new air is being injected to force it out and because of the shear forces of the surfaces it is squeezed between. So it isn't exactly the same as your typical static TIM situation and would need to be measured.

Speaking of measured they state right in the whitepaper the performance measurements of the prototype device:

For example, a survey of commercial CPU coolers indicates that a conventional fan-plus-
heat-sink device equal in size to the version 1 prototype device in Figure 6 has a typical
thermal resistance of 0.6 to 0.8 C/W. Our version 1 prototype device on the other hand has a
measured thermal resistance of 0.2 C/W. This represents a huge advance in a field that has
long seen only incremental progress in cooling performance. Moreover, as discussed later,
we have reason to believe that a 2nd
generation prototype could readily achieve a thermal
resistance of <=0.1 C/W in a device of the same size.

Sounds decent for something that's 100% bad. As for replacing parts while the computer is still operating, I don't see why that would be a problem. The motor is accessible right on the top.

[Vivi]

How about keep the heatsink still and spin the case?

Kidding though, if this works it might be cool idea

but i dont trust the way the heat get's transferred :<

[Serra]

In context of theory under perfect situations he's right. You're only going to require more energy to start it up, then the power would much less after it has finished accelerating.
Second point, coefficient of friction of a bearing may be signficantly small such that the extra mass/weight of the heatsink (Which isn't as much as a conventional heatsink) will not contribute as much losses as the reduction/comparison in/to aerodynamic drag that a standard fan experiences in comparison to the spinning heatsink.

Even in imperfect situations he is wrong. Using more power initially - even if the steady-state power draw is the same - is the very definition of not using the same amount of power. I did specify that over time it could come to near-equality if the steady-state is the same, but that's the best it could aim for... and I have a lot of reasons to suspect (as outlined) that the best case scenario is note even remotely plausible.

Thanks for coming out swinging. Read the whitepaper, because a quick skim has already shown me several errors in your logic.

I am going to endeavor to show that it is not. I'm really not intimidated by whitepapers, I've written a few myself. Just calling it a "whitepaper" doesn't mean it's correct.

I reject your premise that there will be inherently more friction than in a fan motor.

Assuming the spirals have about the same area as the fins on a fan, but spin faster, I don't see how it couldn't have less friction. It does also have more mass, which means there will be more weight placed on a spindle somewhere, which will require more energy to overcome. These are really irrefutable facts, I'm not sure why you're arguing.

As for air bearing vs. liquid bearing - that's not actually what's up for debate here. I could make a fan with an air bearing at a conventional heatsink too, so I get to claim that bearing friction is out of the equation. Of course, there are reasons we don't do that too, but let's not get too far off topic.

I also reject the premise that the air gap in this device is exactly the same as a static air gap. The gap is there so air under pressure can be injected into the gap as an air bearing. Air is significantly less viscous than oil in a ball or sleeve bearing so despite the larger bearing surface it is not immediately obvious which has less friction. That would depend on the size of the air gap the pressure of the incoming air versus the clearance of the sleeve bearing, size of the ball bearings, viscosity of the lubricant, etc. And while I feel it is counterintuitive that air would be a good conductor it would be under pressure and in dynamic flow both because new air is being injected to force it out and because of the shear forces of the surfaces it is squeezed between. So it isn't exactly the same as your typical static TIM situation and would need to be measured.

lol. It may be marginally better than static air, but that difference is so small it would be laughable, and here's a number of reasons why outlined below. Your argument is also a bit muddled... you seem to mix in arguing air as a bearing material then transition (seamlessly?) to calling it a good conductor in this application. The first part of that may be somewhat fair - depending - but the second part is 100% wrong, and that's what I was talking about.

1. At best the cooling potential of said air is equivalent to the cooling potential of air moving at that speed over a very flat metal surface. Do you have any idea why no-one creates a heatsink with a large cut in it at the bottom that you point a fan at? Because it doesn't work well (for reasons outlined in #2 and #3). It's basically like adding a cooling fin at the bottom of a heatsink - which would be OK - except for the gap it creates.

2. The air will be pressurized, but we're not talking about much pressure. Certainly less than 1 ATM. But it would take significantly more than 1ATM of pressurized air to even be able to come close to saying its thermal conductivity approaches that of copper (eg. what would be there were it not for that gap). In fact, I don't think there is any form of air which would meet that requirement... liquid air isn't even that conductive!

3. The size of the gap is significantly greater than what you would see on a flat traditional heatsink/flat CPU. So while the air may impart some miniscule aid in cooling from moving, it's also working against itself because heat has to move through that much more air. It's like having 3ft of styrofoam instead of 3 inches (in fact, the actual scale probably shows a greater deviation than that) - it's intuitively worse as a conductor. The best model would be to use this area like a vapor chamber, but that requires a seal all along the outside, which would absolutely result in notably more friction and power required.

So given it's not particularly assisting cooling, nor is it transferring heat at even a fraction of the speed that copper can, and the gap is much larger than you would see with flat items pressed together by design rather than separated by enough space to account for wobble by design, please explain to me how that air gap isn't something you could likely call akin to a static air gap on a heatsink?

Speaking of measured they state right in the whitepaper the performance measurements of the prototype device:

I argue that his methodology is either flawed, he's wrong, or he's lying. This isn't masters-level particle physics... this is pretty commonplace stuff and there is no way a large air gap is beneficial in conductive thermal transfer. End of story.

Sounds decent for something that's 100% bad. As for replacing parts while the computer is still operating, I don't see why that would be a problem. The motor is accessible right on the top.

Sounds are deceiving from the manufacturer. Like nVidia claiming their next tegra is faster than a Core2Duo (go look at that thread).

As for replacing parts - if you take off the motor you stop the heatsink, which means that you do sit there with a thin copper film on top of static air gap between fins. Pick up a heatsink a short distance off a CPU for a bit and see how long it lasts until thermal shutdown. You're allowed to put a thin piece of copper on top of the CPU first to simulate a very small plate on top of a CPU as in this design. I think you'll see it doesn't last long enough to properly replace such a part.



Oh, and as another reason this won't work well at all and make it a thoroughly pointless product, remember that we migrated away from the solid base + air movement in favor of heatpipes for a reason. Even with turbo fans pointed at a quality pre-heatpipe heatsink, the cooling power was just less than was possible with a regular fan over a heatpipe-style heatsink, and that distinction only grew when looking at bigger fans on heatpipe heatsinks with the correct fin density. Fancy spinning model aside, that's all that is occurring here - air moving over fins. Except instead of a heatpipe to facilitate tranferring heat from hotspots to extreme ends of a heatsink quickly, we get an AIR GAP and solid copper after that. Oh, plus a dead spot in the middle where the motor is.

This whole project is a giant leap backwards. I'd like to meet with the boss of the person who designed this and explain to them why they might as well just fire him and give me half his salary as I would be saving them the long-term costs of a bad employee and mass-production of badly designed items. Heck for the other half I'll even toss them some designs for a new type of cooler that isn't inherently worse than existing products for 10 distinct reasons.

[kuroikenshi]

How about keep the heatsink still and spin the case?

Lets keep the computer still, and spin the whole house instead!!!

[Solus Corvus]

Even in imperfect situations he is wrong. Using more power initially - even if the steady-state power draw is the same - is the very definition of not using the same amount of power. I did specify that over time it could come to near-equality if the steady-state is the same, but that's the best it could aim for... and I have a lot of reasons to suspect (as outlined) that the best case scenario is note even remotely plausible.

It would use less power in general usage however if the initial spin-up power was greater but the steady state power was lower. You have shown exactly zero evidence that the steady state power necessarily has to be the same or greater. It could be lower given the low friction of air bearings. The power consumption data is in the whitepaper.

[bamtan2]

I'd like to meet with the boss of the person who designed this and explain to them why they might as well just fire him and give me half his salary as I would be saving them the long-term costs of a bad employee and mass-production of badly designed items.

rofl. you guys need a virtual fist fight to settle this. winner gets a leaked bulldozer benchmark. raise your dukes... and... FIGHT!

[kaktus1907]

Lets keep the computer still, and spin the whole house instead!!!

wait keep the whole house and spin the earth instead.. oh well that's already spinning !!

[Serra]

It would use less power in general usage however if the initial spin-up power was greater but the steady state power was lower. You have shown exactly zero evidence that the steady state power necessarily has to be the same or greater. It could be lower given the low friction of air bearings. The power consumption data is in the whitepaper.

Your probably didn't notice - I edited my post to respond to your claims directly after posting. I didn't see your post on the 2nd page until after I hit reply. I believe I outlined my position on why this cooler will not meet or exceed the performance of any current-generation coolers in any regard sufficiently.


Edit: And seriously, did YOU read the whitepaper? You realize he's claiming 5x the power benefit by rotating his heatsink versus using a regular fan, right? He also claims his contraption uses 20w. That means 100w for a fan, which is preposterous unless you're choosing a very high RPM fan. And really, no, he's just plain not using 1/5 the power. This whole thing reads like a research paper that shows conclusively that me using lightblub brand A instead of brand B has a direct effect on the weather outside my house.

[vitaminc]

Interesting concept but who the hell is going to use this?

Standardized 120mm/92mm/80mm fans worked well enough. Why use proprietary parts that could have higher chance of failure.

[DarthShader]

Serra, I recommend reading the whitepaper a bit more before fuming out. You would find nice graphs showing actual consumption numbers, not just the maximum designed for, you would read how that air gap wouldn't be a hindrance in that case, how a second version doubling the performance is planned and you would look less ridiculous now.

I personaly think this will be noisy when inside a PC and won't find it's way into consumer PCs. They might make laboratory measurments but that will mean little in real world scenario.

Interesting concept but who the hell is going to use this?

Industry, millitary. The consumption numbers that are shown in the little table that Serra is ignorantly reffering to are a military standard.

[Solus Corvus]

Assuming the spirals have about the same area as the fins on a fan, but spin faster, I don't see how it couldn't have less friction. It does also have more mass, which means there will be more weight placed on a spindle somewhere, which will require more energy to overcome. These are really irrefutable facts, I'm not sure why you're arguing.

As for air bearing vs. liquid bearing - that's not actually what's up for debate here. I could make a fan with an air bearing at a conventional heatsink too, so I get to claim that bearing friction is out of the equation. Of course, there are reasons we don't do that too, but let's not get too far off topic.

A fan has to fight the additional resistance from backpressure through the heatsink. In this heatsink the fins are the cooling surface and air exits fighting only ambient air pressure. It is akin to running a fan on a heatsink versus running a fan in open air - for any given volume of air moved the first scenario will require more power.

Spindle friction will be relatively insignificant compared to bearing friction. And while you could easily make a fan with air bearings (many have already been made) it would have to be massive because there isn't enough bearing surface in a small fan to be properly stabilized by air under self-fed pressure.

lol. It may be marginally better than static air, but that difference is so small it would be laughable, and here's a number of reasons why outlined below. Your argument is also a bit muddled... you seem to mix in arguing air as a bearing material then transition (seamlessly?) to calling it a good conductor in this application. The first part of that may be somewhat fair - depending - but the second part is 100% wrong, and that's what I was talking about.

Air is both a bearing lubricant fluid and a heat transfer material, hence both are applicable to the argument. The friction of the bearing surface speaks directly to the power efficiency of the device (lower friction means power savings). The thermal conductivity of the air speaks directly to the overall performance of the heatsink. Sorry if I wasn't clear about why I mentioned both aspects.

1. At best the cooling potential of said air is equivalent to the cooling potential of air moving at that speed over a very flat metal surface. Do you have any idea why no-one creates a heatsink with a large cut in it at the bottom that you point a fan at? Because it doesn't work well (for reasons outlined in #2 and #3). It's basically like adding a cooling fin at the bottom of a heatsink - which would be OK - except for the gap it creates.

No it is not the same as air being blown over a flat surface. The shear between the surfaces creates turbulence and boundary layer conditions that are nothing like what you'd get from blowing air out of a nozzle.

2. The air will be pressurized, but we're not talking about much pressure. Certainly less than 1 ATM. But it would take significantly more than 1ATM of pressurized air to even be able to come close to saying its thermal conductivity approaches that of copper (eg. what would be there were it not for that gap). In fact, I don't think there is any form of air which would meet that requirement... liquid air isn't even that conductive!

The whole point of air bearings is that the air is under greater pressure than the surrounding ambient. Your first two sentences indicate a flawed understanding of how air bearings work. Air bearings typically operate under very high pressure. Air bearings at less than ambient pressure would be extremely poor for most applications because air pressure on the external surfaces would be forcing the surfaces together. Think of air hockey, would it work if the air pressure under the puck was less than atmospheric pressure?

Secondly it isn't only the pressure of the air that enhances conductivity. Heat conduction in a fluid is also highly dependent on fluid movement, mixing, boundary layer size, and turbulence. The shear between the surfaces and small irregularities in the surface either from manufacturing irregularities or by design and the movement of the surface contribute to those factors.

3. The size of the gap is significantly greater than what you would see on a flat traditional heatsink/flat CPU. So while the air may impart some miniscule aid in cooling from moving, it's also working against itself because heat has to move through that much more air. It's like having 3ft of styrofoam instead of 3 inches (in fact, the actual scale probably shows a greater deviation than that) - it's intuitively worse as a conductor. The best model would be to use this area like a vapor chamber, but that requires a seal all along the outside, which would absolutely result in notably more friction and power required.

All I am saying is that you are trying to compare a small distance of static air to a larger distance of turbulent moving air under pressure. They aren't the same situation. It's a bad analogy.

So given it's not particularly assisting cooling, nor is it transferring heat at even a fraction of the speed that copper can, and the gap is much larger than you would see with flat items pressed together by design rather than separated by enough space to account for wobble by design, please explain to me how that air gap isn't something you could likely call akin to a static air gap on a heatsink?

Because in the second situation the air is moving. Not only that, it is moving out of the gap and being replenished by fresh air.

I argue that his methodology is either flawed, he's wrong, or he's lying. This isn't masters-level particle physics... this is pretty commonplace stuff and there is no way a large air gap is beneficial in conductive thermal transfer. End of story.

Nobody is claiming an air gap, with moving air or not, has better conductivity than solid material, not even the author. The reason for air rather than a higher conductivity fluid is for power savings, that's it. Theoretically you could design a similar HS with a liquid filled gap, but the motor would have to be significantly more powerful.

As for replacing parts - if you take off the motor you stop the heatsink, which means that you do sit there with a thin copper film on top of static air gap between fins. Pick up a heatsink a short distance off a CPU for a bit and see how long it lasts until thermal shutdown. You're allowed to put a thin piece of copper on top of the CPU first to simulate a very small plate on top of a CPU as in this design. I think you'll see it doesn't last long enough to properly replace such a part.

That wouldn't be as much of a problem if it is designed so that when the motor is removed the top surface and bottom surface come into contact, minimizing the gap. Obviously there would still be a rather limited timeframe for replacement though.

Oh, and as another reason this won't work well at all and make it a thoroughly pointless product, remember that we migrated away from the solid base + air movement in favor of heatpipes for a reason. Even with turbo fans pointed at a quality pre-heatpipe heatsink, the cooling power was just less than was possible with a regular fan over a heatpipe-style heatsink, and that distinction only grew when looking at bigger fans on heatpipe heatsinks with the correct fin density. Fancy spinning model aside, that's all that is occurring here - air moving over fins. Except instead of a heatpipe to facilitate tranferring heat from hotspots to extreme ends of a heatsink quickly, we get an AIR GAP and solid copper after that. Oh, plus a dead spot in the middle where the motor is.

I think you have really missed the point. Nobody is saying that the air gap doesn't hinder conductivity. The author spends many pages describing in detail the various factors related to performance of the air gap. It's the most notable weakness in the design, IMO.

The point is that this isn't the same thing as blowing air across fins of the equivalent surface area. We moved to large heat piped heatsinks because the boundary layer between the moving air and the fins is the most significant limiting factor in heat dissipation. The way around it we have adopted is simply to increase the surface area. But this design shrinks the boundary layer by a factor of 10 by moving the fins instead. The boundary layer is in an "accelerating frame of reference" so inertia within the fluid in the boundary layer helps move it away from the surface, in addition to the normal effect of motion in the surrounding fluid. What is being put forth in the paper is that this effect is more significant than any negatives caused by the air gap.


Lastly, I can see that this is getting emotional so I'm going to bow out. I think you have missed some important details but I may be falling prey to bias myself since Sandia National Labs is right around the corner from me.

[zalbard]

wait keep the whole house and spin the earth instead.. oh well that's already spinning !!

Too bad the cooling performance sucks. I blame the RPM value. Moar jigawattz!

[CrazyNutz]

I have to fully agree with Serra here. This is total BS.

1). There is no way spinning a heatsink rather than a fan will consume less power. The heatsink just becomes the fan.
2). Air gap between the CPU and Spinning heat sink? LOL.. This is why we use TIM to get rid of air gaps. The air will be a better insulator than a conductor. You would have nearly the same results if you just pointed a fan at the top of the bare CPU.
3). Someone is getting shammed here. EDIT: It's us, the taxpayers getting shammed, http://www.sandia.gov/ Sandia National Laboratories is funded by US gov..lol

[STEvil]

It would use less power in general usage however if the initial spin-up power was greater but the steady state power was lower. You have shown exactly zero evidence that the steady state power necessarily has to be the same or greater. It could be lower given the low friction of air bearings. The power consumption data is in the whitepaper.

Moving air (CFM) requires power. If either a plastic fan or a metal fan are used it makes no difference assuming similar fin designs are used to move the required volume of air. Given that this heatsink proposes to cause a high-pressure area in order to cause an air bearing affect it will need to use enough power to create the above atmospheric static pressure area.

Now I admit this is an interesting technical concept and may have applications that are realistic in the future, but at the current build quality it is nothing more than a gimmick which will be prone to failure. A much more simplistic heatsink could be constructed to perform its job without even needing a fan which would substantially increase reliability for a military purpose. Yes it would be larger, but it would be much more tolerant of environmental factors such as dust, lint, hair, etc.. and would require much less power (none).

[CrazyNutz]

Look at the diagram. It's incorrect, It depicts the heat sink rotating clockwise and the airflow direction entering the center of the heat sink. The air would only flow in this direction if the heat sink was rotating counterclockwise.

http://techreport.com/discussions.x/21262

[Solus Corvus]

LOL. I'm not going to argue over it anymore, it's really not worth it. These points were addressed in the paper. I'm beginning to think that people made up their mind before even reading a word of it.

[Serra]

At the end of the day Solus, here is what it's about:

Nobody is claiming an air gap, with moving air or not, has better conductivity than solid material, not even the author. The reason for air rather than a higher conductivity fluid is for power savings, that's it. Theoretically you could design a similar HS with a liquid filled gap, but the motor would have to be significantly more powerful.

The claim is that:
A. Thermal conductivity in this heatsink is orders of magnitude worse due to the air gap versus solid copper (and much, much worse vs. a heatpipe). There is no questioning that fact. You agree with this fact
B. Smaller shear area makes up for magnitudes worse heat conduction to the point that this can/does outperform current-gen heatsinks.

[C. The fact that heat is travelling away from the processor slower is irrelevant; this heatsink actually has lower thermal resistance than a standard copper/heatpipe heatsink.]


No, that's flat-out wrong. If it were just about having smaller shear really producing results THAT much better than simply using a higher speed fan would yield better results than it does, as faster air does mean less shear area. But I think we've all pointed a number of Vantec Tornado's at a heatsink and seen that all we lose is a degree or two versus a standard fan.

Edit: Hell, I've seen people spraying water jets at heatsinks before, fairly high-power water jets, and the additional cooling just wasn't that much better. Certainly not better than water-cooling. Yet that's what this thing would HAVE to be if it were better than top-end air - as good as water cooling (as top-end air is about on par with low end water these days).


Once you recognize that chain is inherently incorrect you'll start to see why this whitepaper is complete bunk.


Edit II: As for not reading it - I did read it. I've even been to post-secondary for engineering and I do understand the lingo. But that doesn't mean he isn't wrong. His experiments and his methods are flawed. Well, not flawed - he's trying to sell a product to the government... it's written in a marketing way. That's why the word "revolutionary" appears in there as many times as it does. No serious whitepaper would use that word more than once.

[Solus Corvus]

No, I don't agree with A, B, or C. I think I explained my position clear enough that you don't have to distort it.

Edit: My bottom line is he lists his methodology, data, and equations. I don't see any particular problem with them so far. If you have more accurate equations or testing data that proves it's a bare fraud or whatever then feel free to post them. We can compare and determine which is more likely true ourselves. Just saying that others need to have more understanding before they can see it your way sounds like an argument from authority. Well surprise, you might know the lingo, but so do I. Feel free to post your data.

In the end what really matters is if it gets turned into a product. While it is still quite a long time from being a production ready technology, if it does what he says then I don't think it will be ignored. But even if it is eventually sold I don't really expect the people calling it a fraud to apologize to him.

[Serra]

One last try and I'll stay out of the thread from here on, I promise.

No, I don't agree with A, B, or C. I think I explained my position clear enough that you don't have to distort it.

Perhaps I did not word "A" specifically enough for you; allow me to detail the reasoning behind it.

0. Let's assume for the sake of argument that the heatsink in this discussion is made of copper and that any other heatsink we compare against is copper. This makes things easier. It should be noted however that in the paper his heatsink is indeed not made of copper. But the basic properties of thermal conductivity are the same regardless of material, provided they are both made of the same material and that material is not some metamaterial with odd properties similar to air itself.

1. This heatsink, from a basic materials perspective, has the same thermal conductivity as a regular copper heatsink if they are both made of (eg.) copper.

2. A solid-copper heatsink is actually much less thermally conductive than a heatpipe system. We know this for a fact and can verify it by common experience.

3. Current heatsinks make use of heatpipes. Thus their ability to remove heat from the source is greater than that of a solid heatsink. Much greater, in fact.

4. Air is a horrible natural medium for heat conductivity. Copper has a conductivity of ~400 W/(m.K). Air, even highly pressurized well beyond anything this system will ever see, has a conductivity of at most maybe 0.05 W/(m.K). It is approximately 10,000 times worse as a conductor. Real-world, it's probably more like 40,000 times worse.

5. Thermal conductivity becomes more difficult at boundary areas; that is to say, copper does not like transferring heat to air, nor air to heat... nor air to water, or metal to water, etc.

6. This heatsink incorporates, by design, a gap between the heat source and the actual heat sink that is filled with air. This gap is orders of magnitude larger and more prevalent than what is seen in a typical heatsink where there is micropitting and such.


As a result of the above, even if the spinning portion itself was superior to a traditional heatsink (which is definitely up for debate, even in "version 2.0" with taller fins) there is a thermal conductivity issue between that spinning plate and the actual heat source. Current heatsinks use heatpipes to quickly move heat away; this heatsink uses an air gap to decrease total thermal conductivity of the heatsink as a system.

This can be overcome if the heatsink portion is in fact that much cooler than the bottom plate, however it needs to be so much colder that it makes up for having a pad between the cooling portion and the heating portion which is OVER 10,000 TIMES WORSE THAN COPPER, and even worse than that when compared to a heatpipe. And, again, let's remember that heat does not like travelling between mediums (part of why copper wics are far superior to other wics in heatpipes).


Bottom line - Do you really, truly believe spinning the top as shown can cool the top portion THAT much more effectively versus a current heatsink? I mean, enough to overcome that gigantic difference? I would actually do the math to demonstrate just how much cooler the top portion has to be, but intuitively I know that on a quality HS with a good fan on it the fins and heatpipes just above the bottom are actually pretty much cool to the touch, which would mean it would have to go sub-ambient, which is definitely out of the question.

[th3pwn3r]

I'm beginning to think that people made up their mind before even reading a word of it.

Just barely eh?

[kuroikenshi]

Too bad the cooling performance sucks. I blame the RPM value. Moar jigawattz!

No wait!!!!
lets keep the whole universe still, that way we can reach absolute zero and run SUB SUB temps!!!!



**Edit**
BTW on a serious note I have read the white papers, enquired to engineers and subject matter experts on this field, and got laughed at...
so its decided, its either rotate the planet, or leave the universe still

[Solus Corvus]

[snip]

I'm not going to argue the functionality of the device anymore. The author goes into extreme detail about these points so it really isn't worth reiterating here except for clarity, to which I have done my best. If you want me to point out anything I'll say that you should rethink points 4 and 5 and how they relate to the conditions present within the gap (specifically the effects of shear on the fluid boundary layer and the effects of forced convection and turbulence upon thermal conduction in a fluid).

Bottom line - Do you really, truly believe spinning the top as shown can cool the top portion THAT much more effectively versus a current heatsink? I mean, enough to overcome that gigantic difference? I would actually do the math to demonstrate just how much cooler the top portion has to be, but intuitively I know that on a quality HS with a good fan on it the fins and heatpipes just above the bottom are actually pretty much cool to the touch, which would mean it would have to go sub-ambient, which is definitely out of the question.

I would say that from an epistemological point of view it takes a lot more than a single whitepaper to make me believe in something. The author may very well be wrong or a fraud, though I don't have any evidence of this. Followup research by other scientists and product development will have to be done before I'd "believe" it. And even if I were to believe this single paper that doesn't really have anything to do with the validity of the argument. I have been wrong countless times before (think BD release date, potential effectiveness of lucid hydra, etc), and it wouldn't be the last time. I admit my mistakes and don't shrink from being grilled on them. But lending weight to or detracting from my arguments based on my belief would be an argument from authority on my part or an ad hominem on yours. It's an irrelevant distraction that detracts from the real points being made.

I am not saying that I am convinced that this thing is really as effective as claimed or that it will make for a great product. Like you and many others here my initial reaction was that an air gap is counterintuitive and goes against everything I know about heatsinks. But I am willing to face the possibility that my intuition is incorrect. Think back on when heatpipes were first being introduced in CPU heatsinks. There were lots of people who thought they couldn't work, were a gimmick, etc. Then people cut them open and found no obvious conducting fluid inside and the fecal matter really hit the axial flow turbine. Intuition can be misleading, there are still lots of people that have a hard time wrapping their head around the fact that a seemingly empty tube can conduct heat really well. I'm just happy that a lab the caliber of Sandia is working on something mundane as a better CPU heatsink. I'm interested in hearing about their work in this arena even if it isn't proven yet or goes against my intuitive grasp. And I think others should keep an open mind too, being wrong is an important aspect of learning and growth not something to be feared.

[kuroikenshi]

^^ well if the copper tube was vacuum (no air inside) that would increase conductivity by several fold, air is a poor heat conductor. These are the principles of how thermal vacuum tubes operate, so this is where I leave it.

Gaps and rotating parts which also fill the role of heat conducting simply do not work, also you have the issue of friction, and the heat generated by that effect alone.

[Solus Corvus]

Speaking of not being able to wrap your head around heatpipes...

[kuroikenshi]

Speaking of not being able to wrap your head around heatpipes...

I can, that's why I said what I said, heats moves better passively inside a pipe in a vacuum over any other method more efficiently (cost/effectiveness)