Heat pump and A/C theory for the Guru's
I am posing this as a theoretical, based on my limited understanding of how exactly the systems work, so bear with me.
I think I understand the basic function of an air conditioning system. Compression of a gas, pushed through an orifice or expansion tube, to decompress the gas into a lower pressured vessel, causes the cooling effect. Is this basically correct? The efficiency of the unit is based on it's ability to remove the heat from the compression side (evaporator?) to lower head pressure, and to remove the cold from the low pressure side (condenser?) as the desired product.
Is a heat pump basically just an air conditioning unit run in reverse, in order to use the heat generated as the desired product?
Now basing a theory on these two points, and having learned that the heat pump's capabilities become increasingly limited when the temperature outside drops below 40*F, as the air being passed over the outside unit is insufficiently warm enough to remove the cold produced by the unit (and why my unit has aux/emergency heat)...
... Why can you not simply have your outside unit plumbed into an evaporator that is buried below ground?
One idea (granted, it's far fetched) would be to have such a grid in a sub-surface tank. Ground temperature water-over-coil vs. outside air-over-coil, using the fairly stable ground temperatures to maintain water temperature. Would this be feasible? Or would the ground not be able to transfer the heat/cold rapidly enough to be effective? (this is assuming there is some type of circulation of the water over the coil, mechanical or otherwise)
Or has this concept been sufficiently beaten-to-death in the past? I tried to Google the concept and either my search criteria is bunk (or I don't know what to search for specifically) or there aren't any posting of this kind available. Any ideas to support this or as why this would not work?
