1 / 20

GeoExchange Technologies Utility Geothermal Working Group Webcast April 18, 2006

GeoExchange Technologies Utility Geothermal Working Group Webcast April 18, 2006. Chiloquin Community Center: 16 vertical boreholes + water-water heat pump providing radiant floor heating and cooling. Andrew Chiasson Geo-Heat Center Oregon Institute of Technology. Slide 2.

john
Download Presentation

GeoExchange Technologies Utility Geothermal Working Group Webcast April 18, 2006

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. GeoExchange Technologies Utility Geothermal Working Group Webcast April 18, 2006 Chiloquin Community Center: 16 vertical boreholes + water-water heat pump providing radiant floor heating and cooling Andrew Chiasson Geo-Heat Center Oregon Institute of Technology

  2. Slide 2 Presentation Outline • Overview of geothermal heat pump (GeoExchange) systems • Brief history • System components • Areas of recent technology improvements • Heat pump equipment • Thermal conductivity testing • Borehole heat exchanger design • Hybrid systems • Computer-aided simulation methods • New perspectives • Loads integration • Community loops • Sustainable buildings (LEEDS, etc.) Detroit, MI Australia

  3. Slide 3 Overview:Brief Historical Summary • Early days • Open-loop systems using groundwater wells or surface water • First commercial applications beginning in 1940s • 1970s - early 1980s • Beginnings of R & D of closed loop systems (simultaneously in Sweden and U.S.) • Several 1980s failures of air-source heat pumps gave all heat pumps a bad reputation • Late 1980s - 2000 • Emergence and slow growth of GHP market • Continuing R & D; development of design tools and manuals • Certifications for designers through various organizations (IGSHPA, ASHRAE, AEE)

  4. Slide 4 Overview:What do GHP systems provide? • Heating • Cooling • Hot water • Humidity control • Ice making Residential Heat Pump …but also… • Energy efficiency • Decreased maintenance • Decreased space needs • Low operating costs • Comfort & air quality Lowell, MA • No outdoor equipment (no noise or outdoor maintenance) • For utilities: reduced peak electrical loads in summer, additional electrical use in winter

  5. Slide 5 Components of GHP Systems • Earth connection • Closed-loop (vertical, horizontal, lake or pond) • Open-loop • Water-source heat pump • Vapor-compression cycle • Interior heating/ cooling distribution subsystem • Conventional ductwork • Radiant system 3 2 1

  6. Slide 6 Components:Types of Earth Connection Vertical (GCHP) • Rocky ground • More expensive • Little land used • High efficiency per unit length Horizontal (GCHP) • Most land used • Less expensive, easier to install • Ground temperature varies Groundwater (GWHP) • Aquifer+Injection • Lower cost than closed-loop • Regulations • Possible fouling/scaling concerns

  7. Slide 7 Components:Types of Earth Connection Surface Water (SWHP) • Low cost • Integrate into landscape • Different heat transfer processes (evaporation, thermal storage) Standing Column Well (SCW) • Hard rock geology with high quality groundwater • Low ft/ton and very little land area • Open & closed-loop characteristics • Groundwater regulations

  8. Slide 8 Heat Gains and Losses BoreholeThermal Resistance Borehole Spacing or Design Considerations Undisturbed Earth Temperature Average Thermal Conductivity & Heat Capacity

  9. Slide 9 Technology Improvements:Heat Pump Equipment • Numerous small improvements over past 10 years • Variable-speed fans • Microprocessor controls (allows easier troubleshooting) • Improved water-refrigerant coils • New refrigerants (non-ozone depleting) • Low-temperature heat pumps for refrigeration applications

  10. Slide 10 Technology Improvements:Thermal Conductivity Testing • ASHRAE-sponsored research project in (1999-2000) compiled field-test methods and data analysis methods • Testing time depends on borehole design • 40-hour test is recommended • Probably not cost-effective on small commercial and residential projects First generation unit (trailer) Compact testing units

  11. Slide 11 Technology Improvements:Borehole Heat Exchanger Design • Goal is to lower the borehole thermal resistance Geo-Clip Spacers Double U-tubes Thermally-enhanced grouts + improved grout pumps (Bentonite + sand mixtures)

  12. Slide 12 Technology Improvements:Pond Heat Exchanger Design Copper Pond Loop Experiment (OSU) Geo-Lake Plate

  13. Slide 13 Technology Improvements:Standing Column Well Design • ASHRAE-sponsored research project (2000-2002) • Identified several hundreds of installations, mostly in New England and Eastern Canada (areas of hard rock with good groundwater quality) • Good for locations with limited land area • Detailed computer modelling identified the most important parameters as: • Bleed strategy • Borehole depth • Rock thermal & hydraulic properties • Borehole diameter • Water table depth 500 – 2000 ft

  14. Slide 14 Technology Improvements:Hybrid Systems • Current ASHRAE-sponsored research project just underway • Motivation is due to necessity of large loops in applications with unbalanced annual loads (due to thermal storage effects of soils/rocks) • A supplemental piece of equipment handles some portion of the load: • Boiler • Solar collectors • Cooling tower • Pond or swimming pool • Shallow heat rejecters • What is the optimal system design and control (time of day? year?)

  15. Slide 15 Hybrid Systems:Shallow (or surface) Heat Rejecters • SHRs (shallow or surface) heat rejecters • Shallow horizontal loops are used to thermally “unload” vertical borehole field in winter or during cool nights • Additional benefit of slab warming and snow melt assistance • Could also incorporate turf systems or storm water ponds Photo credit: Marvin Smith, OSU

  16. Slide 16 Hybrid Systems:Solar Applications University of Wyoming Test Site • Uses some old ideas of borehole heat storage with some new concepts 4 single U-tube vertical borehole heat exchangers (200 ft deep) Source: E. Kjellsson, IEA Heat Pump Newsletter, Vol. 23, No. 1

  17. Slide 17 Technology Improvements:Simulation of Complex Systems • Development of many component-based, modular computer models • Driven by hourly weather data • Allows optimization of designs • However, can be cumbersome and not available to everybody • Working toward making these more usable

  18. Slide 18 New Perspectives:Loads Integration with GeoExchange • Example of an ice arena

  19. Slide 19 New Perspectives:Community Loops Lake Las Vegas Resort Closed-Loop in Lake • Not a new idea, but • New ideas of heat exchange • Sewers (gray, black water) • Thermal storage • Several ownership scenarios • Home-owner associations • Third-party • Developer-owned • Utility-owned • Developers are the key Sewer Heat Exchanger Rabtherm Corp. Groundwater Loop, B.C. Central production wells with infiltration galleries at each home

  20. Slide 20 Conclusions • GeoExchange technologies have evolved considerably since their beginnings • Most recent efforts in making GeoExchange more economic include applications that have balanced or shared loads => these applications are almost limited by our imagination • Hybrid systems and integrated load systems can be tricky to design, but we’re currently working toward developing streamlined design tools • GX playing increasingly larger role in sustainable buildings and in reduction in CO2 emissions

More Related