Ya'll...
I just got a call from Cathar (Hi m8!), and we got to "shoot the breeze" about this design.
Maybe it's too early, but this design is going to be very difficult to beat, because anything else that could come close would "require some expensive equipment", as Cathar said, and personally, I believe that the double inpingement effect that this design uses really makes maximum use of the coolant flow.
In any case, I still intend to try it with 2 Johnson pumps, and I might throw in my Little Giant as well, to see if I can throw the coolant in turbulence, even before it hits the microtubes, if that's possible (probably not). Actually, I think I was aiming for turbulence to occur within the microtubes, now that I think about it, before it's jetted.
The problem is that the speed involved is (not "near sonic", I was confused with Radius' inlet) relatively low as it is now (~60 km/h, or 40 mph, from Cathar), and I certainly don't have any hope of increasing that much higher.
I just ran the calc, taking 4 gpm, dividing it by 52 (52 tubes), and assuming that the ID of the tube is 0.033 inch (as linked, above), the flow speed would be 28.9 fps (feet per second), or 19.7 mph (miles per hour).
If I can increase the flow rate above 4 gpm, to say 10 gpm (which would be quite a feat!), then the flow speed through an individual tube increases to 72 fps, or 49 mph.
But I suspect that more than likely, what will actually happen, is that I'm going to hit a wall, where the pumping action will throw more heat into the loop, to the point where the resulting performance would actually decrease.
Send me the block Cathar, and I'll throw lots of pumping action at it!
In the mean time, I'll see if I can make some kind of calculation on the Reynolds number.
Quote:
Turbulence is determined by a dimensionless value called a "Reynolds number." The exact range between turbulent and laminar flow is disagreed upon in some circles.
According to McCabe, Smith, and Harriott, turbulent flow will occur at Reynolds numbers above Re~24,000. Turbulence can be forced by obstructions in the flow as long as the Reynolds number is well above Re=2,100. Below that, there's no way to avoid laminar flow.
Sieder and Tate define turbulent flow for significant heat transfer to be abover Re=100,000.
Reynolds number is equal to linear velocity multiplied by channel diameter multiplied by density, all divided by viscosity. So to get turbulent flow by increasing flow only, you'd have to increase flow rate a hundred times.
Re = V * D * rho / mu
(posted by Alchemy, in the Radius thread)
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