Page 197 - Geothermal Energy Renewable Energy and The Environment

184 Geothermal Energy: Renewable Energy and the Environment

T = T i T = T i T = T 2 T = T 2 T = T i
V = V i V = V 1 V = V 2 V = V 3 V = V i
P = P i P = P 1 P = P 2 P = P 3 P = P i

1 2 3 4

Refrigerator Room
interior air air
FIGUre 10.1 Schematic representation of the thermodynamic cycles used to remove air from the interior of
a refrigerator and transfer it to the room within which the refrigerator is housed. This process is indistinguish-
able from that characteristic of a Carnot cycle, as presented in Chapter 3.

Heat pump

Grouted borehole

FIGUre 10.2 Schematic of a ground source heat pump plumbing system utilizing a single borehole. The
borehole depth is typically about 90 meters, with the piping grouted in place using a cement–clay mixture
that has high thermal conductivity. The heat pump and HVAC unit are typically located in a service closet in
the building.

trenches or other excavated settings (Ochsner 2008). Open loop designs also exist that use ground-
water that is pumped through a heat pump from a water well and then reinjected back into the
groundwater system. The basic principles of heat exchange of an open loop system are the same as
those of a closed loop system. However, management of the resource is different and will be treated
separately in a later section.