Advertisement

Design of Horizontal Ground Heat Exchangers in Sub-arctic Conditions—Sensitivity to Undisturbed Ground Temperatures

  • Robbin Garber-Slaght
  • Jeffrey D. SpitlerEmail author
Conference paper
Part of the Springer Proceedings in Energy book series (SPE)

Abstract

Application of ground source heat pumps (GSHPs) in extreme cold climates can be challenging due to the long heating season even with heat pumps designed and marketed for colder climates. One challenge (of several) is design of the ground heat exchanger under conditions where the desired minimum heat pump entering fluid temperature (EFT) is close to the undisturbed ground temperature (UGT). Furthermore, ground heat exchanger (GHE) models used for design purposes and/or energy calculation purposes don’t usually incorporate freezing and thawing of the soil. This is the case whether the freezing/thawing is induced by surface conditions or by heat transfer between the ground heat exchanger and the surrounding soil. A recently developed model (Xing and Spitler in Sci Technol Built Environ 23(5), 809–825, 2017, [1]) implemented in a simulation-based ground heat exchanger design tool (Oklahoma State University in GLHEPro 5.0 for Windows—Users’ Guide. Stillwater, 2016, [2]) incorporates the effect of surface-condition-induced freezing/thawing when calculating a 2nd-order harmonic approximation for the undisturbed ground temperature. This paper examines the suitability of this harmonic model in GHE design applications by comparing the predicted GHE design to the actual design of a GHE at the Cold Climate Housing Research Center (CCHRC) in Fairbanks, Alaska. Field measurements of UGT and GHE performance are used to examine the limitations of the harmonic model.

Keywords

Ground-source heat pumps Horizontal ground heat exchangers 

References

  1. 1.
    L. Xing, J.D. Spitler, Prediction of undisturbed ground temperature using analytical and numerical modeling. Part II: Methodology for developing a world-wide dataset. Sci. Technol. Built Environ. 23(5), 809–825 (2017)CrossRefGoogle Scholar
  2. 2.
    Oklahoma State University, GLHEPro 5.0 for Windows—Users’ Guide. Stillwater (2016)Google Scholar
  3. 3.
    J. Fourier, The Analytical Theory of Heat (Translation of the 1822 work Théorie analytique de la chaleur.) (University Press, Cambridge, 1878)Google Scholar
  4. 4.
    W. Thomson, On the reduction of observations of underground temperature; with application to Professor Forbes’s Edinburgh observations, and the continued Calton Hill Series. Lond. Edinb. Dublin Philos. Mag. J. Sci. XXII Fourth Ser. 23–34, 121–185 (1861)Google Scholar
  5. 5.
    W.D. Collins, Temperature of Water Available for Industrial Use in the United States (Water Supply Paper, USGS, 1925)Google Scholar
  6. 6.
    J.-H. Chang, Ground Temperature (Observatory, Harvard University, Bluehill Met, 1958)Google Scholar
  7. 7.
    L. Xing, J.D. Spitler, Prediction of undisturbed ground temperature using analytical and numerical modeling. Part I: model development and experimental validation. Sci. Technol. Built Environ. 23(5), 787–808 (2017)CrossRefGoogle Scholar
  8. 8.
    L. Xing, J.D. Spitler, A. Bandyopadhyay, Prediction of undisturbed ground temperature using analytical and numerical modeling. Part III: experimental validation of a world-wide dataset. Sci. Technol. Built Environ. 23(5), 826–842 (2017)CrossRefGoogle Scholar
  9. 9.
    R.M. Grundmann, Improved Design Methods for Ground Heat Exchangers. M.S. Thesis, Oklahoma State University (2016)Google Scholar
  10. 10.
    Z. Xiong, D.E. Fisher, J.D. Spitler, Development and validation of a Slinky™ ground heat exchanger model. Appl. Energy 141, 57–69 (2015)CrossRefGoogle Scholar
  11. 11.
    R. Garber-Slaght, R. Peterson, in Can ground source heat pumps perform well in Alaska?, IGSHPA Technical/ Research Conference Proceedings. Denver, pp. 62–70, 14–16 Mar 2017. http://dx.doi.org/10.22488/okstate.17.000525
  12. 12.
    Oklahoma State University, Ground Source Heat Pump Residential and Light Commercial Design and Installation Guide (Stillwater, OK, IGSHPA, 2009)Google Scholar
  13. 13.
    Oklahoma State University, Closed-Loop Geothermal Systems—Slinky Installation Guide (Stillwater, OK, IGSHPA, 1994)Google Scholar
  14. 14.
    Data provided by V. Romanovsky, U. Alaska. August 7. (2017)Google Scholar
  15. 15.
    J.R. Cullin, J.D. Spitler, A computationally efficient hybrid time step methodology for simulation of ground heat exchangers. Geothermics 40(2), 144–156 (2011)CrossRefGoogle Scholar

Copyright information

© Springer Nature Switzerland AG 2019

Authors and Affiliations

  1. 1.Cold Climate Housing Research CenterFairbanksUSA
  2. 2.Oklahoma State UniversityStillwaterUSA

Personalised recommendations