Sandia, Cooler Master and CoolChip Kinetik rotating heatsink CPU cooler.

The begin: Sandia rotating heat sink cooler

Back in 2010. Sandia announced their research on air bearing rotating heat sink cooler.

The rotating heat sink

Sandia rotating heat sink cooler. 

As you can see this is very interesting cooler. The ordinary coolers consist of static heat sink and fan. Here you can see something else, the heat sink itself has a shape of centrifugal fan and it's rotating! It function both heat sink and fan in the same time. Now what makes this setup so interesting is that it is dust proof. Many of you have seen heat sink completely clogged by thick layer of dust looking like fabric.

clogged heat sink

The fan also becomes dusty but it's moving and it just can't keep so much dust. So in this case when the heat sink is rotating it can become little dusty but it can't be clogged. And this mean easier maintenance. And stable performance in time, without performance drop when the heat sink is becoming too dusty.

The air bearing.

But a question raises how the heat from the heat source will transfer to the heat sink? The answer is simple - air bearing.

Sandia cooler summary

When the air gap is very small and the fan is rotating at high speed the air in the gap is moving as well and thus giving very small thermal resistance in order of  0.02 °C/W(check the . file in the link under the image). The smaller the gap the better, here we talk about 0.001″ air gap.
So basically, when the air gap is very small the fast moving air is hitting the hot base plate, get heated itself and after this it hit the heat sink transferring the heat to the heat sink. Because the same air is moving fast towards the heat sink too.

The reduced boundary layer

The boundary layer is effect in the physics where an air moving near surface has slower speed than air at greater distance.

Thermal boundary layer

As Sandia labs state "The centrifugal pumping effect eliminates 90% of the insulating boundary layer (“dead air”) enveloping the cooling fins". It means that even the air near the fins caught by the boundary layer get pushed out. Because the centrifugal force is working on it no matter that is it in the boundary layer.(Just simple and not exactly correct explanation but it pretty much means this)

Quieter operation

The increased effectiveness and the reduced amount directly transfer to reduced noise, actually the fact that here we have only fan and not fins behind fan and huge amount of air that needs to pass through it eliminates a lot of the noise.

The MIT reward issue: CoolChip $200K Clean Energy Prize

In 2011 there were a fuse about a CoolChip Technology that won the MIT Clean Enery Prize competition. Soon after the reward being granted a lot of people asked the question "Hey. Isn't this the sandia cooler?" putting MIT in uncomfortable situation. They couldn't easy say that they have made mistake and besides CoolChip already got the money. Fortunately for them CoolChip and Sandia didn't go in lawsuit but settle the things out of the court by CoolChip agreeing to point the intellectual property of Sandia in a proper way. This allowed to MIT to announce later that CoolChip now properly reference the inventor of the technology and that now they are within the rules.

Back then I was hoping to see CPU cooler made by the Sandia technology but it seems that I had to wait.

The Partnership: Cooler Master and CoolChip work together

Now 4 years later, a little bit by accident I found a video about the new Cooler Master and CoolChip Kinetic cooler. It seems that CoolChip hasn't drop the idea for the kinetic cooler but give the OEM to Cooler Master which have very good experience and know how of the cooling technologies.

For example Cooler Master have experience in producing vapor chambers for the base plate which is the initial design idea by Sandia.
Now the prototypes are still in pre-alfa states. they don't implement vapor chambers. There are two models. One for small CPUs and the other one for big cores. They are not giving exact information how much Watts of power the cooler can handle. And like I said there is still no vapor chamber on the small one it just have base plate made from aluminum.

Model of the smaller kinetic cooler

The big one however doesn't have vapor chamber but it has heat pipes and small heat sink attached to them around the rotating heat sink of the cooler.

3D model of the bigger kinetic cooler

The heat pipes and their mounting helps spreading out the temperature around the base plate, they also together with their fins helps utilizing the airflow already produced by the rotating kinetic cooler. However despite the fact that maybe this build have better thermal properties, I don't like it since it is loosing the main advantage of the rotating heat sink and this is the dust proof capabilities.

Now these static fins will collect dust like before, and they will be harder to clean because you cant remove the fan. So for me this is just something that they want to show, and not so practical, unless of course you are not looking for low profile cooler. And of course the smaller one doesn't have such problems.

Lets move to the next point - the air-gap.

This schematic is shown on CoolChip website. Please pay attention that the base plate is not actually flat but it has this circular pattern shape shown on the picture in order to increase the surface of the air gap that transfer the heat.

Base plate contact surface shape

In this way they can increase the heat transferring surface between the two discs few times. The more cylinders you have the more surface you got. But when I look at their prototype they are using CNC machines to produce their prototypes and they are limited by the material properties and the cutting tool properties itself.

The fins shape

CoolChip fins

Now if you look at the sandia first prototype in the begin of the page it has the same fin number coming from the center and leading to the end. Maybe it has better flow properties but the guys from CoolChip wanted to increase the surface. So they used this trick, they have made the fins with the same thickness without thicker part but instead in the outer part of the circle where the there is more space they added second row of fins. I doubt that this increase the airflow but for sure it increase the surface.