DHE (downhole heat exchangers). [Downhole Heat Exchangers (DHE)]
The use of downhole heat exchangers (DHE) for residential or commercial space and domestic water heating and other applications has several desirable features. Systems are nearly or completely passive -- that is, no or very little geothermal water or steam is produced from the well either reducing or completely eliminating surface environmental concerns and the need for disposal systems or injection wells. Initial cost of pumps and installation are eliminated or reduced along with pumping power costs and maintenance costs associated with pumping often corrosive geothermal fluids. Many residential and small commercial systems do not require circulating pumps because the density difference in the incoming and outgoing sides of the loop are sufficient to overcome circulating friction losses in the entire system. The major disadvantage of DHEs is their dependence on natural heat flow. In areas where geological conditions provide high permeability and a natural hydraulic gradient, DHEs can provide a substantial quantity of heat. A single 500-ft (152 m) well in Klamath Falls, Oregon, supplies over one megawatt thermal and output is apparently limited by the surface area of pipe that can be installed in the well bore. In contrast, DHEs used in conjunction with heat pumps may supply less than 8 KW from a well of similar depth. Here output is limited by conductive heat flow with perhaps a small contribution from convection near the well bore. The highest capacity DHE reported to date, in Turkey, supplies 6 MW thermal from an 820-ft (250 m) well. There were two main goals for this project. The first was to gather, disseminate and exchange internationally information on DHES. The second was to perform experiments that would provide insight into well bore/aquifer interaction and thereby provide more information on which to base DHE designs. 27 refs., 31 figs., 3 tabs.
- Research Organization:
- Oregon Inst. of Tech., Klamath Falls, OR (USA). Geo-Heat Center
- Sponsoring Organization:
- DOE/CE
- DOE Contract Number:
- FG07-90ID13040
- OSTI ID:
- 6304383
- Report Number(s):
- DOE/ID/13040-1; ON: DE91006620
- Country of Publication:
- United States
- Language:
- English
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Large downhole heat exchanger in Turkey and Oregon
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Related Subjects
GEOTHERMAL WELLS
DESIGN
PERFORMANCE TESTING
HEAT EXCHANGERS
INFORMATION DISSEMINATION
AUSTRIA
GEOTHERMAL SPACE HEATING
GEOTHERMAL WATER HEATING
KLAMATH FALLS
NEVADA
NEW ZEALAND
SWITZERLAND
TURKEY
ASIA
AUSTRALASIA
DEVELOPING COUNTRIES
EUROPE
FEDERAL REGION IX
GEOTHERMAL HEATING
HEATING
KGRA
MIDDLE EAST
NORTH AMERICA
SPACE HEATING
TESTING
USA
WATER HEATING
WELLS
WESTERN EUROPE
Geothermal Legacy
151000* - Geothermal Energy- Direct Energy Utilization