# Thermodynamics Problem for a Project I Want to Build

1. Jun 26, 2013

### mhumm2

Hello. I have an idea for a geo-thermal cooling system which I want to use to cool the CPU and GPU of my computer. My goal is quiet (fan-less, and dust-less) computing with a very high cool factor (as in Fonzy, not temperature) <grin>. I suppose you'd call this a proof of design concept. So here's the problem:

I will be pumping a water-based coolant through copper pipe that is immersed in ground water at the bottom of a well. I call the The copper pipe array a "georad" (geothermal radiator). Here's the problem: I need to know the size of the georad I have to build.

I know:

- the Max CPU temp (60°C), Desired Max temp (40°C)
- the Max GPU temp (70°C), Desired Max temp (50°C)
- the flow rate of the coolant (5 Liters/min)
- the temp of the ground water (15°C)
- amount of heat generated by pump: negligable
- amount of temp xfer between georad and computer: negligable

I'll be using 3/4" copper pipe. I need an equasion that will give me X surface area of copper needed. Then I could simply convert that surface area into Y number of 3/4" copper pipes totalling the same surface area.

Please let me know if there's some variable I'm missing. The givens above are worst case in order to derive the maximum surface area needed. I realize the water blocks on the CPU and GPU (which will be in series by the way) have significant bearing on this problem, but i have no specs or numbers on them. Like my high-school physics class using "frictionless" pulleys, let's assume the water blocks are 100% efficient.

Last edited: Jun 26, 2013
2. Jun 26, 2013

### Khashishi

Depends on your CPU and GPU. They put out a certain number of watts depending on how much computation they are doing. This is something that is kind of hard to calculate from first principles, so you should just look at some similar water cooled systems and see what they use.

3. Jun 28, 2013

### mhumm2

Khashishi,

Thank you for your response. Currently, I'm aware of 3 geothermal cooling systems including the one I want to build, as described above. I have studied traditional cooling systems for years. As far as my CPU: 125Watts, and my GPU: 150Watts. Thanks again.

mhumm2

4. Jun 29, 2013

### mhumm2

Added information: The wall thickness of the copper is 1/8"