Quote from: Vigil on June 24, 2013, 10:53:26 PM

Quote from: Ente on June 24, 2013, 08:22:24 AM

Quote from: Vigil on June 23, 2013, 03:24:16 PM

I am an engineer with a background in aerodynamics/fluids and am capable of performing Heat/CFD simulations. Is there any way I can contribute to the heat sink/dissipation design. I can't promise anything but I can try if I had more understanding of what the goals/design are.

Awesome! :-)
Quick question about watercooling:
How about building a simple aluminum "box" from 5mm aluminum, no fins or similar, and screwing the K16s on that? We could use both sides of the cooler and it would be pretty easy to build.
I guess even with a low waterstream it should cool the board enough?
Cooling the water with a big radiator and a fan, outside, 35°C outside-temp worstcase.
With a few dozen watt per 100cm² this should be a piece of cake for the actual cooler?

Your gut-feeling is enough for me now :-)
(Else we might migrate to the K16 DIY thread)

Ente

So the water is running through the inside of the "box"? The largest problem with any setup like this is making sure that there is conduction between the chips and aluminum to the water. There will be no convective cooling in this setup (such as blowing air over the chip without any heat-sink). I also wouldn't consider setting something like this up along with a radiator and fan as "easy" unless you already have this stuff around. But I would have to see a design to make sure I understand what you are talking about.

Edit: OK, I've seen a design similar to what you are talking about. So, these current designs are placing heatsinks/aluminum housing on the underside of the board... how is heat being conducted from the thermal pad on the chip, through the board, and to the heatsink/aluminum? If it is just silicon then there may be a conduction/heat-transfer issue. It seems that this QFN design isn't really made for external heat dissipation.

About silicon-to-heatsink: I collected some numbers here:
https://bitcointalk.org/index.php?topic=190731.msg2295823;topicseen#msg2295823
My conclusion is we'll be in the 10 to 15 degree ballpark, difference between junction and coolingmedium.

Yes, normally we want some turbulence in the water, for quick mixing of the fresh, cold water with the heatsink and warmer water.
In our setup, where we ultimately cool the water with room-temp air, I am sure there will be no thermal gradient over the whole setup at all! I.e. the water going into the heatsink and the water coming out will be the same temperature, in equilibrium. And with such low power over such a high area - I am sure such a minimalistic waterblock is enough. Having a potent enough radiator, with a strong enough fan, is a totally different story though ;-)

So. Who can tell me anything about running a bit of water over flat aluminum, which is heated with <50w per 100cm²?

Ente