Geothermals

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Hi everyone.

As I am not a thermodynamics guy, but an electronics guy, I beg for your asistance on this forum on my lack of heat transfer thinking.

 

Planning to drill a ~100m deep well in my backyard, it is supposed to reach well beyond a stable ~20°C thermal layer; circulate water trough a long 2" U shaped polyethilene pipe to provide home cooling in ~30°C summers and help warming in ~0°C winters : A convection geothermal heat pump.

 

What are the effects of the water velocity on amount-of-heat transfer ? From analogies on internal combustion engines, the faster the flow the greater the heat transfer - that is why racing engines have high flow coolant pumps- . On the other side, a slow flow speed allows the circulating water to reach the stable temperature and deliver all its potential temperature.

 

What is more convenient ? A small mass flowing at a higher temperature differential or a larger mass flowing at a lesser temperature differential ?

Seems to my ignorance that any will work equally, as the amount-of-heat would by Q=mass x (t2-t1) ; leaving good convection radiators, low losses, proper insulation of pipes, system efficiency to determine its effectivity.

Is the ideal flow speed the one that will allow the flow to reach within a couple of degrees to ensure there will be heat transfer at all times?

 

Thanks,

Miguel