CPU Cooler Air Conditioner Mk1 – The Test

The last time we were here, I left you with a quick construction that tested a concept that I had had in my head for a few years, but never got around to verifying:  Linking a CPU Cooler to a Heatsink immersed in icy water to transfer the heat in the air into the icy water, blowing cooled air into one’s face.  That was the theory, anyway.

That said, if life has taught me anything, it is that theory and practice are two different things.  It is all well and good for me to claim that the CPU Cooler Air Conditioner Mk.1 works because my theory sounds good and the air seems to be cooler when it leaves the fan, but to really prove this idea, I need to put some numbers to it.  To this end I have obtained a meat thermometer from my local supermarket, which isn’t much compared to a UKAS-certified thermocouple and reader, but it allows readings to one decimal place and should be reasonably accurate.

The Method

The Control

The first thing to do is quite obviously to establish what the Control is, which in this case would be the ambient air temperature.  There is also a dial thermometer mounted on the wall in my room, which I will monitor to gauge whether the ambient temperature is increasing or decreasing during the course of the experiments.

The Fan Test

The next thing to be done is to determine what temperature readings would be obtained with the fan from each system running at full tilt on it’s own.  This will provide what is, in effect, a second control for the system under test, ensuring that we know whether it is the fan doing all the work.  The temperature probe will be raised into the airflow next to the fan for ten minutes, after which the temperature reading will be recorded.

The Ice-Water Test

This is where the systems are put to the test-proper.  Each system will be tested with the same amount of ice (250g, as this is what will fill the cheese-grater tub), immersed in water almost to the top of the container, leaving a gap to allow for melting ice to fill the tub further.  The full setup is then allowed to work for fifteen minutes, after which the temperature of the air leaving the fan is recorded.  After this test is completed, the water will be drained and the remaining ice salvaged for use in the next test.

The Ice-Salt-Water Test

The final test is the same as the Ice-Water test above, but with a controlled amount of salt (50g) stirred into the Ice-Water mixture; this is likely to saturate the water with salt at the temperatures and volumes we are dealing with.  This is to test the theory that adding salt to the water will lower the freezing point of the water, which will permit it to attain a lower temperature and thus chill the air (or the heatsink in the case of the CPU Cooler Air Conditioner Mk.1) to a lower temperature.  After this test the salt-water and ice are both discarded.

The Results

Setup Temperature (℃)
Ambient Air Temperature (Control) 25.8
Silverstone RL4Z S1803212H-3M 180mm Fan 26.1
Zalman CNPS9900 Max 26
Silverstone RL4Z S1803212H-3M + Ice-Water Cheese Grater 26.7
Silverstone RL4Z S1803212H-3M + Ice-Salt-Water Cheese Grater 26.8
CPU Cooler Air Conditioner Mk.1 25.3
CPU Cooler Air Conditioner Mk.1 (Ice-Salt-Water) 25.5

The Verdict:  Inconclusive

There are some conclusions to be drawn from the results beyond the notion that you might as well just blow a fan on yourself:

  • The Air Conditioner does indicate that the concept works, but the low level of cooling suggests that it is inefficient.
  • The Fan + Cheese Grater solution is a complete farce, with it’s results indicating a rise in air temperatures.
  • Adding salt to the water does not increase cooling effects – possibly the opposite is true – and it could be harmful to the unit in the long run with increased risks of corrosion.
Possible improvements:
  1. Add a Peltier plate between the CPU Cooler and the Heatsink to act as a heat pump to force heat energy into the ice water.
  2. Some kind of agitator mechanism to stir the water, to help prevent algae growth and circulate cool water around the heatsink.
  3. As TIM needs a solvent to clean it off of a CPU after use, I doubt that it can be washed away; that said, it would help to create a waterproof barrier around the heatsink on the lid to prevent contamination of the water by the TIM, possibly allowing the water to be drunk after use (once it has cooled down!).

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