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Can I pick your collective brains about an idea for a home cooling solution that I have thought of? (discuss.tchncs.de)

submitted 1 year ago by DontNoodles@discuss.tchncs.de to c/diy@beehaw.org

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I'm planning to construct a home sometime in the near future in hot, arid part of the country. Obviously, keeping the home cool is a major concern and I've been considering all available options.

One of the recurrent ideas discussed online is using geothermal cooling. But I think I don't have enough land to implement it. I have a related idea though.

Water supplied during set hours of the day by the municipality is fairly cool even during the summer months and it is a common practice around here to first let it collect in an underground tank and then pump it to the overhead tank as needed.

What if I create a closed loop system of circulating water with two car radiators: one in the underground tank, submerged in cool water and another in the living area of the home with a fan blowing behind it.

Do you think it'll cause perceptible change in room temperature if there is, say, a temperature difference of 10 degrees Celsius between water and ambiance? I intend it to only reduce the load on the air conditioners and/or just delay the use of AC.

What kind of math/physics will be needed to assess if this is a feasibility? I tried looking hard but could not find anyone else discussing this idea, so I'm reaching out to you guys.

Thank you for your time.

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[–] shanghaibebop@beehaw.org 2 points 1 year ago* (last edited 1 year ago) (1 children)

No, unless you are leveraging evaporative cooling, that amount of circulation isn’t going to get you much.

Just get a real geothermal hvac system if you have the opportunity. Incredibly efficient.

Back of the napkin conversion: 20btu/sqft recommended cooling capacity. 1btu = 252 calories (small)

A 60k btu cooling needs

15120000 gram degrees C of water. Assuming you have perfect heat exchanger on both ends, that’s 15120 liters-degrees circulated per hour.

Pumping that much water alone is going to be quite a bit of energy.

Then you have the problem of heat exchanger. There are lots of sizing mostly based on the deltaT temperature difference.

Realistically, without some agent evaporating and recondensing, you’ll have a massive water to air heat exchanger that’s not practical at all.

If you want to do more research yourself, heat exchanger sizing can be found in mechanical engineering and chemical engineering handbooks.

[–] DontNoodles@discuss.tchncs.de 1 points 1 year ago

Thank you for your reply. It has given me the factors to consider and the terms to look for. I'm going to cross verify the values you have quoted and if it is indeed as bleak, I'll just temper my expectations.

But I'm not giving up on it totally yet. What I'm still not sure is how geothermal cooling can provide more heat exchange as compared to the system I'm proposing. At most geothermal systems also only have a few tens on meters of piping underground.