post #31 of 31
Quote:
Originally Posted by Caleal View Post

I'll say it again, turbulence is a desirable thing when you are trying to transfer heat to or from the coolant in a water block, or any other type of heat exchanger.
Check out this article from the American Institute of Physics.
http://www.aip.org/tip/INPHFA/vol-2/iss-4/p18.pdf
The 2nd page under "Fluid Flow" is the relevant paragraph.
That article is the lightest reading one a Google search poped up with for me.
At some point Google decided that I liked highly technical engineering and science papers and journals when I do a search for anything even a little sciency. rolleyes.gif

I think you misunderstood. I agree insofar as turbulence is beneficial as far as increasing the surface area of the coolant goes, which is something the article you linked supports:
Quote:
Turbulent flow produces better heat
transfer, because it mixes the fluid. Laminar-flow heat
transfer relies entirely on the thermal conductivity of the
fluid to transfer heat from inside a stream to a heat-
exchanger wall.

The point I was trying to draw out of this is that despite that positive effect, turbulence disrupts the flow as the article also supports a few sentences later:
Quote:
The type of flow determines how much pressure a
fluid loses as it moves through a heat exchanger. This is
important because higher pressure drops require more
pumping power.

Ultimately, we're left with the need to make a compromise: either to put more coolant in contact with the block by increasing the flowrate, or by using a more restrictive block that encourages turbulence. This also relates to the concern with pumps adding heat to the loop. A more restrictive loop will require a pump that can build more pressure but motors like that will struggle at generating a high flow-rate without a higher heat output. The simplest solution is to acquire a high RPM motor and tailor the loop restriction to be low enough for it to handle, the other solution is to decouple the pump from the impeller so it doesn't make contact with the coolant at all.
Quote:
Originally Posted by ilec 
If it is cavitation you'll see pock marking - as in the picture below. (Though obviously in a smaller scale)

Hmm I'll have to break out the eye loupe to check that for sure, but it's good to know there's a way to confirm that or rule it out.
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