| Abstract |
Direct Geoexhange Heat Pumps (DGHPs) provide chilling via refrigerant-carrying copper loops buried in the ground which act as a condenser and achieve higher efficiency than equivalent air source heat pumps because of the ground’s constant heat capacity. DGHPs are particularly suited to desert environments with more extreme ambient temperatures. The Australian Square Kilometer Array Pathfinder (ASKAP) radio telescope will be an array of 36 x 12-m diameter parabolic dish antennae situated in Boolardy, WA each requiring 5 – 9 kWth cooling for computer equipment and pedestal. Following successful tests of a prototype installation at Marsfield, NSW (ground temperature 17 C) a DGHP is installed at antenna site #29 (the first erected). The DGHP provides chilling to a variable test load (3.6, 4.8, 8.4, 9.6, 13.2 kW) via a 200 L water buffer. 6 x 30m bores containing copper loops deliver up to 14 kW of chilling to maintain 13 - 15 C water temperature in the buffer. 5 data bores monitor ground temperature variation in the centre of the 6 active bores and at 0.3, 0.6, 3.0, 6.0 m (outside the bore field). System pressures & power are also monitored. A higher-than-expected baseline ground temperature of 27 C is measured and verified by three methods. The nominal 14 kW DGHP can maintain 15 C water temperature at all loads including 13.2 kW. Note that 0.5 kW pump heating means the effective load is 13.7 kW. We describe the results from this field installation in detail and present an abridged set of data. |