
The fanless heatsink: Silent, dust-immune, and almost ready for prime time - mrsebastian
http://www.extremetech.com/computing/131656-the-fanless-heatsink-silent-dust-immune-and-almost-ready-for-prime-time
======
ojbyrne
"fanless" seems like unnecessary hyperbole. The heatsink is a fan, which is
cool enough that it doesn't need to be oversold.

~~~
m_eiman
It's also not "silent", but rather "quiet". Marketing overload.

------
jholman
Many of the questions in this comments thread (e.g. safety, e.g. vertical
mounting, e.g. cost associated with the bearings, e.g. the basis of the 7%
figure) are already answered directly or indirectly in a year-old Q&A article
that was linked from TFA.

[http://www.extremetech.com/computing/90272-the-fanless-
spinn...](http://www.extremetech.com/computing/90272-the-fanless-spinning-
heatsink-your-questions-answered-by-the-inventor?print)

Not very good-HN-citizen-ish to post questions without putting any work at all
into looking for the answers, is it?

------
moonboots
Does this heatsink work when it's mounted vertically? The
"hydroplaning"/floating effect seems to suggest the heatsink must be resting
on the base instead of suspended sideways.

~~~
thrownawayfan
From the slides at
[https://ip.sandia.gov/techpdfs/Sandia%20Cooler%20presentatio...](https://ip.sandia.gov/techpdfs/Sandia%20Cooler%20presentation.pdf)

>Q: Can the device be mounted in any orientation?

>A: Yes—the air bearing assembly is held together by magnetic attraction
(between the stator and permanent-magnet rotor).

------
hetman
I remember seeing this a year ago. It's a bit worrying that in that time they
still haven't gotten around to building a prototype that will be as quiet as
the claimed final product. While that doesn't mean it can't be done, it may
point to deeper issues in the project such as yet unaddressed technical
challenges or lack of funding (which might in turn suggest lack of investor
conviction).

Personally I'm curious what the failure rate will look like with these things.
Given it will probably be higher than existing PC cooling fans which are
moving lighter loads, this may indeed be a problem.

~~~
adventureful
Most larger manufacturing companies move at a glacier pace. I could see Apple
making a quick decision to use these and then having them in models within a
year, but few other manufacturing companies are willing to move like that.

~~~
K2h
My impression was that Apple intentionally lagged the cutting edge curve to
error on stability and sound user experience. I would be very surprised to see
them go in the direction of moving parts - instead I would expect them to
continue in the direction of all solid state (no moving parts) as much as
possible.

------
robomartin
From the article: "This centrifugal force is what gives the Sandia Cooler such
massive efficiency, too."

That is not correct. The efficiency boost comes from the very efficient
transfer of heat from the CPU to the spinning fan/heat exchanger by,
effectively, using the very thin air-gap under the impeller. The rotation of
the impeller breaks the boundary layer in the airgap and you get good heat
transfer across a very thin gap.

The airflow over the machined aluminum blades and, in general, the rotation of
the entire impeller assembly, serve to keep the heat exchanger free from dust
accumulation (which restricts heat flow).

Of course, as many have pointed out, it remains to be seen how easily this
concept translates to a mass-manufactured low-cost solution in terms of
performance and reliability under varying conditions.

I've done a ton of heat flow FEA work when working on various approaches to
cool a custom high-power LED array (1,500W power-in). We could get reasonable
results with complex forced-air solutions and relatively expensive custom
machined heatsinks as well as carefully modeled airflow controls. In these
cases the solutions were always very large (volume).

When we switched to fluid-based cooling things changed dramatically. One of
the design challenges was to maintain a narrow delta-T across the LED array.
This is because thermal uniformity was required in order to have uniform
performance across the array. The fluid solution, with some tricks, could
easily achieve ten times better thermal uniformity than the air-cooled
approach. And, in addition to this, cool the entire array to a much lower
final temperature.

A fluid cooling system was constructed using only a small fluid pump and no
air-moving fans at all. A passive natural convection radiator could easily
handle the heat-load in a normal air-conditioned office environment.

While I have not looked at the specific case of cooling a CPU, based on my
experience I have to say that far greater gains can be had by rapidly moving
heat from the CPU surface using fluid-based cooling. This, effectively,
creates the opportunity for much greater surface extension than can reasonably
be applied to the small surface area of a CPU.

Again, I have never studied CPU cooling, but I am not sure that this 150W
cooling limit applies to fluid-based cooling. I can see building a systems
that can very easily move 150W, or even double that, using a relatively simple
fluidic cooler. At some level it is a matter of how many molecules of the
fluid you can move across the CPU-side heat exchanger per unit time. The
answer to that is "a lot".

I can't see the Sandia or any other pure air-based cooling system used for CPU
cooling at the extremes. The assembly would have to be very precisely
manufactured and lots of work would have to be done in order to ensure that
vibrations and harmonics of the motor drive system itself don't cause damage
to the circuit board. If the system needs to have an impeller spinning at 2K
RPM or more, lots of work needs to go into making it safe for servicing as a
metal impeller like that can shred fingers in an instant.

Finally, there's the question of the mass of the spinning impeller. In order
to transfer heat into the impeller blades you are limited to certain geometry.
If the spinning base and/or the blades get too thin you simply won't be able
to move the heat out no matter how well it can move from the stationary plate
up to the revolving disk. This is critical and it means that there are certain
minimum geometry constraints that are likely to make the impeller somewhat
massive. From my FEA work on heat transfer I know that you can only go so thin
on blades before they become useless past a few millimeters above the heatsink
base-plate. The same is the case here.

What I can see is the use of this concept to create a fluid based solution
that uses a liquid to quickly move heat from a CPU to a much larger heat
exchanger that uses the Sandia heatsink to move heat into the surrounding air,
and, thereby, cool the CPU. Even at that, I'd like to see data comparing
conventional forced-air convection cooling of the external heat exchanger and
even a comparison to a natural convection solution.

~~~
mercuryrising
It sounds like you were using liquid cooling, did you ever try phase change
cooling? Something like this
([http://www.youtube.com/watch?v=Z_X_hgtlJpA&t=36](http://www.youtube.com/watch?v=Z_X_hgtlJpA&t=36))?
I saw a demo of it a couple years ago, really cool stuff.

~~~
robomartin
No. Not flexible enough for what we needed to do and, in some ways, limited in
performance. For the right applications phase change heat transfer is
fantastic.

EDIT: My comment has to do with phase change cooling of the type implemented
with sealed copper tubes moving heat from one end to the other using a phase
change fluid inside. This full-immersion phase change cooling setup is a
something entirely different. I don't know anything about it.

------
stevewilber
The video mentions that transferring heat to the impeller is a challenge, but
it wasn't clear to me how they overcame this. Is the space between the CPU and
the impeller so small that heat can be transferred efficiently?

If that is the case, I wonder how cheaply these could be produced given the
incredibly tight clearance.

~~~
thrownawayfan
There's a whitepaper available here [http://prod.sandia.gov/techlib/access-
control.cgi/2010/10025...](http://prod.sandia.gov/techlib/access-
control.cgi/2010/100258.pdf)

Their data suggests that the air gap provides minimal resistance to the flow
of heat. As for the clearance, they've stated that unusually high-precision
manufacturing is not required for the two surfaces.

~~~
nialo
Re: clearance, while .001" clearance isn't something I'd want in a design
particularly, modern machine tools are good enough that you get flatness and
surface finish good enough to not have problems at .001" clearance basically
free on any machined surface.

------
johnpmayer
I'm somewhat confused; do demonstrate how quiet it is, they turn off the loud
motor that keeps it running?

~~~
latch
Because it's a prototype without noise filters or any other attempt to reduce
motor noise. His point in turning off the motor was to show that there's
little noise caused by the blades chopping through the air - which is where
fan noise actually comes from.

~~~
moe
You are probably right.

Still, why didn't they just attach a normal fan-motor and then compare that
side-by-side to a standard-fan?

It always seems a little fishy when a marketing-video does anything but the
obvious.

~~~
latch
If I had to guess I'd say it's because the video is targeted at people for
which this will be obvious. They aren't looking to sell this directly to
consumers. They want to license the cooling technology. As far as they are
concerned, the noise of the motor is probably as irrelevant as the bracket's
color.

------
tadfisher
I'm not sure what problem this is trying to solve. I have a truly fanless
heatsink [1] that is ducted to a 120mm case fan at 1000RPM, which is
guaranteed to produce less noise than a 2000RPM rotating metal disaster. A
plus is that there is no air gap necessitating such a high rotation speed.

[1]
[http://www.thermalright.com/new_a_page/product_page/cpu/hr01...](http://www.thermalright.com/new_a_page/product_page/cpu/hr01plus/product_cpu_cooler_hr01plus.htm)

~~~
riobard
You won't be able to fit that fanless heatsink inside a laptop. It's just way
too big.

~~~
colinshark
The demo unit is presumably rated for about 150 watts. A unit rated for the
~40 watts that a laptop creates would be smaller and shorter.

------
tedunangst
_if every conventional heatsink in the US was replaced with a Sandia Cooler,
the country would use 7% less electricity. For the most part, these savings
would come from air conditioning and refrigeration systems_

How does that work? Is the same amount of heat not being expelled from the
chip into the room? Does transferring the heat with a smaller fan somehow make
it smaller heat?

~~~
capnrefsmmat
Transferring heat with a smaller fan requires less power to run the fan. For a
given amount of electricity, the Sandia Cooler can extract more heat from the
processor, so it requires less electricity to keep the processor cool.

~~~
tedunangst
7% of the electricity in a data center goes to spinning CPU fans? I do not
believe that.

~~~
rosser
Not _just_ CPU fans. FTFA, and the latter part of which was included in the
GP's quote:

 _"an ideal replacement for just about every fan-and-heatsink installation in
the world... For the most part, these savings would come from air conditioning
and refrigeration systems..."_

~~~
tedunangst
I know, I read that. The impression I got from the article was that these new
heatsinks were going to be used on the CPUs and that somehow that would
generate less heat. e.g, if Intel makes a lower power chip, a lot of savings
will come from AC, even though Intel isn't making AC systems. It was not
obvious to me (and I still have my doubts) that "every fan-and-heatsink" was
referring to AC systems as well as CPU heatsinks.

------
Uchikoma
The fanless heatsink is a fan. Duh. YMMV but I'd not call it fanless.

~~~
freehunter
"Fanless" might be a bit of a stretch, but it doesn't need _another_ fan.

~~~
Uchikoma
A bit of a stretch, but I'd not call a car "engineless" just because it does
not need _another_ engine ;-)

~~~
freehunter
If every car before it needed both an engine and a car, and now there's a car
that is its own engine, I would give them some leeway to call it an engineless
car. The big draw here is that the heat sink is the same as the fan, instead
of needing to buy both a heatsink _and_ a heatsink fan.

"Fanless" is still weird, I'd prefer to call it integrated.

------
jmsduran
This is a very interesting heatsink design. That said, having a finned
heatsink spinning at 2000+ RPM seems potentially dangerous, especially if
someone were to touch it with their bare fingers while it's operating.

~~~
huhtenberg
Given that it sucks the air in through the central part, it must be spinning
counter clockwise, with external fin ends pointing away from the direction of
spinning. Not 100% safe, but not a finger chopper either.

~~~
verroq
It'd suck to have it grind against any cables.

------
Too
Last time this was one hacker news someone suggested mounting the chip onto
the heatsink and spin the whole thing, without any thermally conductive
bearing. Still an awesome idea imo.

~~~
kintamanimatt
How do you connect the chip to the motherboard though?

~~~
libria
The motherboard spins, too...

------
blt
That part looks really expensive to manufacture. It's machined. Can they make
it out of molded plastic (like fans) or sheet metal (like CPU heatsinks)?

~~~
miahi
Most of the original (boxed) CPU fans are machined. The sheet metal fans are
3rd party and they need costly heatpipes to move the heat away from the
(machined) CPU base. It will be costly because the machined metal fan will
need great balance and a good polish to stay quietly floating above the base
and not jump and rip through the computer's case.

You cannot use plastic as it has a lousy thermal conductivity. You cannot use
copper because great thermal conductivity (2x better than Al) comes with
greater weight (3 times the density of Al).

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dfrey
If this ever makes it to mass market, there will be some bloody knuckles on
people who are trying to make small adjustments to the inside of their
computer case while it is running. It's basically 100 butter knives spinning
at 2000 rpm.

------
gouranga
I was hoping to see something like a peltier heat pump which has no mechanical
parts.

~~~
miahi
A Peltier element only moves the heat from one side to the other. If you don't
have some device to cool the hot side, the element will overheat and burn - so
you still need a big heat exchanger to dissipate the heat into the air.

Also, Peltiers are not really energy efficient.

~~~
gouranga
I said 'like' - I'm aware of the problems :(

------
hexagonal
Previous thread: <https://news.ycombinator.com/item?id=2754725>

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mrgreenfur
This is a year old. Why did slashdot move here?

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simonbarker87
Simple idea, seems obvious when you think about it. Glad this wasn't just a
Peltier device

------
dazmax
I'm hoping Apple is waiting for this to be ready before they update the Mac
Pro hardware.

~~~
veemjeem
unlikely. if you look inside a macpro, you'd see that they have 2 giant fans
that cool the cpu & ram. They pipe the air so that it flows over the cpu
heatsink & ram, but no other components. There's another fan for cooling the
rest of the system. Apple would have to re-engineer the entire case if they
wanted to use the impeller design.

------
excuse-me
I wonder how cheap and reliable are the bearings needed to run a 2000rpm 'fan'
1/1000" above a heat pipe, while being vibrated by hard drives and PSU fans,
shaken around in laptops.

Generally you can have bearings that are small/fast/precise or cheap -
generally not all 4.

~~~
nickolai
I was under the impression that this used a similar principle to the one that
keeps hard drive heads in place. So some reasonable amount of vibration should
not be an issue. On the other hand, assuming a reliability similiar to hard
drives, failures will happen. and in worst case, will send a weighty heatsink
spinning at 2krpm flying inside your computer case. Given how collision-
unfriendly that baby looks, its not something i would want to happen inside my
desktop box.

~~~
excuse-me
Hard drive bearings are big and expensive!

But the heads are mostly kept above the surface by aerodynamic effects -
effectively they are held in a thin air film which stops them touching the
platter.

~~~
hollerith
This new heat sink / fan is like the heads in the hard drive: it floats on a
thin film of air. Consequently, it does not need any conventional bearings.
The video describes it as "using an air bearing".

~~~
excuse-me
It isn't an air-bearing by any normal use of the term.

It still needs a radial bearing to attach it to the motor - especially if you
aren't mounting this perfectly flat and level. It can use an air cushion
effect to reduce the planarity demands of the bearing to keep the heat
transfer surfaces parallel - but this is very different to 'floating' a 10mg
sprung drive head

~~~
Ralith
<http://news.ycombinator.com/item?id=4157104>

