Ducted Zalman 7000CU w/Countercurrent Flow Cooling

Do-It-Yourself Systems
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COUNTER-CURRENT FLOW COOLING


Source of image and text below - http://www.picotech.com/experiments/exchange_principles

"An exchange process, whether it involves heat, gases, solutes, or water, is an important feature in many different physiological processes... One of the most effective exchange principles is the counter-current principle."

"We can use the exchanger for transferring heat, gases, or water between two media separated by a thin membrane that has good thermal conductance or a high conductance for different gases, solutes or water.

With the concurrent flow cooling shown in the image above, the cooling flow initially picks up a lot of heat but this diminishes quickly as the difference in temperature gets smaller. On the other hand, with counter-current flow cooling, the initial themperature difference isn’t as large, but it is maintained throughout, resulting in better cooling.

I tried to use the counter-current flow principle to the fullest in the CPU cooler. The Zalman 7000A seemed the best heatsink candidate for this project.

DUCT DETAILS

First I built a right angle duct with fairly dense foam material with a Panaflo 80L1A fan integrated into it. The other end of the duct is designed to fit into the Zalman 7000A heatsink.

Then I covered the outside of the 7000A with the cuff of a dishwashing glove. As you can see, the stock fan was removed from the heatsink. It is not needed as the Panaflo fan serves the function of blowing the air.

Here's the Panaflo-fanned duct fitted into the heatsink.

How does all this work and what is it supposed to do? The cutaway diagram below helps to explain.


The blue arrows indicate the flow of air between the fins.
The red arrows indicate the flow of heat in the fins.

  • The foam "nozzle" of the duct fits tightly against the heatsink fins, sealing them off from the center space.
  • The fan blows (sucks) up and away from the heatsink.
  • The heat from the CPU moves from the base of the heatsink up into the fins.
  • Now the air enters at two points; both entries provide very efficient cooling airflow:
    • At the top outer edge of the fins, forcing the air to take a long path in the direction opposite to the flow of heat in the fins. This is counter-current flow cooling.
    • Around the base of the heat sink, where the fins are closely spaced and wider. This is cross-flow cooling.


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