Thermodynamics Problem for a Project I Want to Build

[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 equation 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.

Please advise.

 

[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.

 

[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

 

[mhumm2]

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

 

[sardar]

Hello,

Thank you for sharing your project idea with me. It sounds like a very interesting and innovative concept. In order to determine the size of the georad you will need to build, you will need to consider the heat transfer and thermodynamics principles involved.

Firstly, you will need to calculate the amount of heat that needs to be dissipated by the georad in order to maintain the desired maximum temperatures for the CPU and GPU. This can be done using the formula Q = m*Cp*(T2-T1), where Q is the heat energy, m is the mass flow rate of the coolant, Cp is the specific heat capacity of the coolant, and T2-T1 is the temperature difference between the coolant entering and leaving the georad.

Next, you will need to determine the heat transfer coefficient for the georad, which is a measure of how effective it is at transferring heat. This will depend on factors such as the flow rate, pipe material, and surface area of the georad.

Once you have these values, you can use the formula Q = h*A*(T2-T1), where h is the heat transfer coefficient, A is the surface area of the georad, and T2-T1 is the temperature difference between the coolant entering and leaving the georad. Rearranging this formula, you can solve for A, which will give you the required surface area of the georad.

To convert this surface area into the number of 3/4" copper pipes, you will need to consider the cross-sectional area of the pipes and the total surface area of the georad. The number of pipes needed will depend on the size and layout of your georad.

I would also recommend considering the thermal conductivity of the ground water, as this will affect the heat transfer between the georad and the water. Additionally, you may need to consider the insulation of the pipes to prevent heat loss.

I hope this helps and provides a good starting point for your project. Good luck with your design and please let me know if you have any further questions.

Best regards,