Geothermal Cooling - Low Energy Cooling for Sustainable Buildings - page 94

Figure 4.9 System drawing of horizontal heat exchanger coupled to the mechanical ventilation system
During a hot 14-day measurement period in June 2005 an average cooling power
of 1 . 5 kW with a maximum of 4 kW was measured. Due to the close proximity and
low depth of the tubes, the maximum heat dissipation per metre of tube is only 8W.
The pressure drop due to the brine to air heat exchanger amounts to only 12 Pa.
The installed fan needs an electrical power of 30W to overcome this drop, whereas
the brine pump consumes about 60W. This results in maximum COPs of 40 and an
average COP of 18.4 (see Figure 4.11). It can be seen that a phase of heating occurred
Figure 4.10 Measured daily mean temperatures of the soil at 3 . 5m distance from the building ('undis-
turbed') and directly between the earth heat exchanger (EHX) tubes at 1 . 2 m depth