Posted by Jack on December 8, 2006, 1:34 am
I think the future of ground source heat extraction might be bore holes with
a single copper tube 2-3 inches in diameter, and say 100-200 feet long
filled with a benign refrigerant that simply boils from the heat in the
ground. When the heat pump collapses the vapour from header connecting the
borehole pipes, the vapour pressure is reduced and the refrigerant in the
vertical pipes starts to boil thereby releasing latent heat. Transfering
heat through the pipe with latent energy is an efficient scheme I would
think. When the vapour is collapes at the condenser heat exchanger, the
liquid drains back to keep the tubes filled by gravity. Simple. This method
is a bit like the old single steam pipe heating schemes of days gone by. In
a sense the ground becomes the boiler with a never ending fuel supply. The
heat transfer process would be extremely efficient and could eliminate a
pumped condenser loop entirely. Maybe CO2 would work as a refrigerant but
I'm speculating. CO2 would be extracted from the atmosphere and therefore
benign. The key refrigerant, whatever it is would need to be benign and
operate under the appropriate pressure. Just a thought.
Posted by Eeyore on December 8, 2006, 1:10 am
Why copper ?
Posted by Vaughn Simon on December 8, 2006, 1:57 am
What would you suggest?
Posted by Eeyore on December 8, 2006, 2:15 am
Vaughn Simon wrote:
Something less expensive ! Ideally something flexible too. Incidentally I've had
underground copper pipe work corrode ( due to impurities ).
High density plastic seems to be favoured. You also need a heck of a lot more
length btw AIUI.
Posted by Solar Flare on December 8, 2006, 2:34 am
The ground is not an endless supply of heat at the rate you would need
it unless there is circulation going on.