I'm considering building a sealed growroom but aircon seems like such a waste of energy to me since I would have to add another 25% watts just for that.
So I thought about circulating cooler fluid between a car radiator inside the growroom and a large coil of garden hose buried in the ground outside.
Systems like this are popular for aircon/heating but usually involves a heat pump. I want to accomplish this using a circulation pump only.
Assuming a water / ethylene glycol mixture with a heat capacity of 3600 J/l*K (Water is 4192 J/kg*K - i also changed units to liters in the example but this is only ballpark figures) we would need 1 liter of cooling fould being heated by 1 degree K (Celsius) every hour to achieve a cooling effect of 1w.
Per 1K lamp we're talking about circulating 1000 / 60 =~ 17 liters / minute assuming that the exit temperature of the water is a single degree higher than the entry temperature. I believe this could be within reasonable limits.
Now for dehumidification:
If we're aiming for a growroom temperature of 25 deg C then the dewpoint for 50% RH is 14 deg C. If we accept 30 deg C then we're up to 18 deg C.
It doesn't seem unfeasible to achieve that level of cooling assuming 10 deg C water.
In the winter in Denmark it's usually colder than that - we're rarely above a couple of deg C at nighttime and if you're hardcore and dig down a couple of meters you can get 8 deg C water all year round.
Obviously this won't work in California but they got the sun and the shorter daylengths for outside grows so quit complaining
Anyone with some practical or theoretical experience please chime in
Edit: If this subject has been discussed before please drop a note sow e can let this thread die