Pro/Forums - View Single Post - Heatsink Conversion -> Pelt Waterblock

koslov · 04-25-2003, 06:00 PM

Noooooooooo, hit keyboard shortcut for "back" by mistake and lost huge post....

Ok, here we go again:

Here is how I plan to distribute the flow evenly:

I will drill a V-shaped slit into the Lexan, beneath the barb. It is basically like a nozzle on some garden hoses, but the area of the manifold outlet will be about equal to the barb's cross section. The hard part will be drilling into the Lexan at an angle, but it is doable.

JD, I think your evaluation of minichannels for pelt cooling is off. Pelts seem almost better suited for minichannels since you have a larger surface area over which to put fins.

As for pressure drop, consider this:

Cross section of 1/2" tubing: 500mm²
Cross section of 1/2" poly barb: 314mm²
Cross section of flow manifold outlet (6 x 50mm): 300mm²
Cross section of block (5mm fins x 50mm width): 250mm²

Water flows from 500mm² to 314mm² to 300mm² to 250mm². As you can see, most of the pressure drop comes from going from the hose to the barb.

Ben: I don't think .15°C/W is that unreasonable. Remember, I am cooling a 1600mm² area, not the tiny 100mm² area of a CPU. °C/W decreases as surface area increases.

Clamping will be done through bolts going directly through the baseplate. They will not be attached to the top at all, so therefore structural integrity wrt to clamping force is a non-issue.

edit: One more thing I wanted to address:

Hot side thermal resistance greatly affects the core temp of pelt-cooled system:

This is the difference between a .20 °C/W block and a .15 °C/W block. The .02 added on is estimated °C/W of the radiator.

BTW, I used .1 °C/W for cold side resistance, but this was just a wild guess. Anyone have any clue as to what the real value might be for a 100mm² CPU and 1/4" copper cold plate?

04-25-2003, 06:00 PM	#10
koslov Cooling Savant Join Date: Jul 2002 Location: Posts: 264	Noooooooooo, hit keyboard shortcut for "back" by mistake and lost huge post.... Ok, here we go again: Here is how I plan to distribute the flow evenly: I will drill a V-shaped slit into the Lexan, beneath the barb. It is basically like a nozzle on some garden hoses, but the area of the manifold outlet will be about equal to the barb's cross section. The hard part will be drilling into the Lexan at an angle, but it is doable. JD, I think your evaluation of minichannels for pelt cooling is off. Pelts seem almost better suited for minichannels since you have a larger surface area over which to put fins. As for pressure drop, consider this: Cross section of 1/2" tubing: 500mm² Cross section of 1/2" poly barb: 314mm² Cross section of flow manifold outlet (6 x 50mm): 300mm² Cross section of block (5mm fins x 50mm width): 250mm² Water flows from 500mm² to 314mm² to 300mm² to 250mm². As you can see, most of the pressure drop comes from going from the hose to the barb. Ben: I don't think .15°C/W is that unreasonable. Remember, I am cooling a 1600mm² area, not the tiny 100mm² area of a CPU. °C/W decreases as surface area increases. Clamping will be done through bolts going directly through the baseplate. They will not be attached to the top at all, so therefore structural integrity wrt to clamping force is a non-issue. edit: One more thing I wanted to address: Hot side thermal resistance greatly affects the core temp of pelt-cooled system: This is the difference between a .20 °C/W block and a .15 °C/W block. The .02 added on is estimated °C/W of the radiator. BTW, I used .1 °C/W for cold side resistance, but this was just a wild guess. Anyone have any clue as to what the real value might be for a 100mm² CPU and 1/4" copper cold plate? Last edited by koslov; 04-25-2003 at 06:19 PM.