Advertisement

Acta Geotechnica

, Volume 9, Issue 3, pp 367–384 | Cite as

Comparison of two different models for pile thermal response test interpretation

  • Fleur LoveridgeEmail author
  • William Powrie
  • Duncan Nicholson
Research Paper

Abstract

Thermal response tests (TRTs) are regularly used to characterise the thermal resistance of borehole heat exchangers and to assess the thermal conductivity of the surrounding ground. It is becoming common to apply the same in situ testing technique to pile heat exchangers, despite international guidance suggesting that TRTs should be limited to hole diameters of 152 mm (6 in.). This size restriction arises from the increased thermal inertia of larger diameter heat exchangers, which invalidates the assumption of a steady state within the concrete needed to interpret the test data by traditional line source analysis techniques. However, new methods of analysis for pile heat exchangers have recently been developed that take account of the transient behaviour of the pile concrete. This paper applies these new methods to data from a multi-stage TRT conducted on a small diameter test pile. The thermal conductivity and thermal resistance determined using this method are then compared with those from traditional analytical approaches based on a line source analysis. Differences between the approaches are discussed, along with the observation that the thermal resistance may not be constant over the different test stages.

Keywords

Ground source heat pumps Piled foundations Thermal response tests Thermal affects Thermo-active foundations 

List of symbols

Fo

Fourier number (αt/r b 2 )

G

G-function

H

Pile or borehole length

hi

Heat transfer coefficient

Q

Total heating power (W)

q

Heating power per unit length (W/m)

R

Thermal resistance (mK/W)

Rb

Pile thermal resistance (mK/W)

Rc

Concrete resistance (mK/W)

Rp

Pipe resistance (mK/W)

r

Radial position (m)

rb

Pile radius (m)

Sc

Specific heat capacity (J/kg K)

Scv

Volumetric heat capacity (J/m3K)

T

Temperature (K or C)

ΔT

Change in temperature (K or C)

t

Time (s)

α

Thermal diffusivity (m2/s)

γ

Euler’s constant

λ

Thermal conductivity (W/mK)

Subscripts

b

Pile or borehole

c

Concrete

f

Fluid

g

Ground

i

Pipe inner dimensions

in

Inlet

o

Pipe outer dimensions

out

Outlet

p

Pipe

Notes

Acknowledgments

The authors would like to thank Concept Consultants Ltd, Marton Geotechnical Services Ltd and Gecco2 Ltd for their roles in construction of the test pile and carrying out the TRT. The work of Jasmine Low (University of Southampton) and Echo Ouyang (University of Cambridge) in the installation are also gratefully acknowledged. The lead author was funded by the Engineering and Physical Sciences Research Council (research grant number EP/H049010/1).

References

  1. 1.
    ASHRAE (2007) ASHRAE handbook—heating, ventilating, and air-conditioning applications. American Society of Heating, Refrigeration and Air-Conditioning Engineers, Atlanta 2007Google Scholar
  2. 2.
    Austin III, W. A. (1998) Development of an in situ system for measuring ground thermal properties. MSc Thesis, Oklahoma State UniversityGoogle Scholar
  3. 3.
    Austin W, Yavuzturk C, Spitler JD (2000) Development of an in situ system for measuring ground thermal properties. ASHRAE Trans 106(1):365–379Google Scholar
  4. 4.
    Banks D, Withers JG, Cashmore G, Dimelow C (2013) An overview of the results of 61 in situ thermal response tests in the UK. Q J Eng Geol Hydrogeol 46:281–291CrossRefGoogle Scholar
  5. 5.
    Beier RA, Smith MD (2003) Minimum duration of In situ tests on vertical boreholes. ASHRAE Trans 109(2):475–486Google Scholar
  6. 6.
    Bernier M (2001) Ground coupled heat pump system simulation, ASHRAE Transactions 107 (1):605–616Google Scholar
  7. 7.
    Bouazza A, Wang B, Singh RM (2013) Soil effective thermal conductivity from energy pile thermal tests, In: Manassero et al (Eds.) Coupled phenomena in environmental geotechnics, In: Proceedings of the International Symposium, ISSMGE TC 215, Torino, Italy, 1–3 July 2013, Taylor and Francis, London, 211–219Google Scholar
  8. 8.
    Brandl H (1998) Energy piles and diaphragm walls for heat transfer from and into the ground. In: Van Impe PO, Haegemans W (eds) Deep foundations and auger piles. Balkema, Rotterdam, pp 37–60Google Scholar
  9. 9.
    Brettman TPE, Amis T, Kapps M (2010) Thermal conductivity analysis of geothermal energy piles, In: Proceedings of the Geotechnical Challenges in Urban Regeneration Conference, London UK, 26–28 May 2010Google Scholar
  10. 10.
    Carslaw HS, Jaeger JC (1959) Conduction of heat in solids, Second Edition edn. Oxford University Press, OxfordGoogle Scholar
  11. 11.
    Fujii H, Okubo H, Nishi K, Itoi R, Ohyama K, Shibata K (2009) An improved thermal response test for U-tube ground heat exchanger based on optical fiber thermometers. Geothermics 38(4):399–406CrossRefGoogle Scholar
  12. 12.
    Gehlin S (1998) Thermal response test—in situ measurement of thermal properties in hard rock, Licentiate Thesis, Lulea Technical UniversityGoogle Scholar
  13. 13.
    Gehlin, S. (2002) Thermal response test, model development and evaluation, Doctoral Thesis, Lulea Technical UniversityGoogle Scholar
  14. 14.
    Gnielinski V (1976) New equation for heat and mass transfer in turbulent pipe and channel flow. Int Chem Eng 16:359–368Google Scholar
  15. 15.
    GSHPA (2011) Closed-loop vertical borehole design, installation and materials standards Issue 1.0, September 2011. Ground source heat pump association, Milton KeynesGoogle Scholar
  16. 16.
    He MM, Lam HN (2006) Study of geothermal seasonal cooling storage system with energy piles. In: Proceedings of ECOSTOCK Conference, Atlanta City, NJ, USA, 2006. https://intraweb.stockton.edu/eyos/energy_studies/content/docs/FINAL_PAPERS/11A-2.pdf Accessed 6 June 2013
  17. 17.
    Hellstrom G (1991) Ground heat storage theory, Thermal Analysis of Duct Storage Systems. Department of Mathematical Physics, University of Lund, SwedenGoogle Scholar
  18. 18.
    Hemmingway P, Long M (2013) Energy piles: site investigation and analysis. Proc Inst Civil Eng Geotech Eng 166(6):561–575CrossRefGoogle Scholar
  19. 19.
    IGSHPA (2007) Closed-loop/geothermal heat pump systems: design and installation standards, international ground source heat pump association/Oklahoma State UniversityGoogle Scholar
  20. 20.
    Ingersoll LR, Zobel OJ, Ingersoll AC (1954) Heat conduction with engineering and geological applications, 3rd edn. McGraw-Hill, New YorkzbMATHGoogle Scholar
  21. 21.
    Javed S, Claesson J (2011) New analytical and numerical solutions for the short time analysis of vertical ground heat exchangers. ASHRAE Trans 117(1):13–21Google Scholar
  22. 22.
    Javed S, Fahlen P (2011) Thermal response testing of a multiple borehole ground heat exchanger. Int J Low Carbon Technol 6:141–148CrossRefGoogle Scholar
  23. 23.
    Javed S, Claesson J, Beier RA (2011) Recovery times after thermal response tests on vertical borehole heat exchangers, In: Proceedings of 23rd IIR Int. Congress of Refrigeration (ICR2011), Prague, Czech RepublicGoogle Scholar
  24. 24.
    Javed S, Nakos H, Claesson J (2012) A method to evaluate thermal response tests on groundwater filled boreholes. ASHRAE Trans 118(1):540–549Google Scholar
  25. 25.
    Kavanaugh SP, Xie L, Martin C (2001) Investigation of methods for determining soil and rock formation thermal properties from short-term field tests, ASHRAE 1118-TRPGoogle Scholar
  26. 26.
    Laloui L, Di Donna A (2011) Understanding the behaviour of energy geo-structures. Proc Inst Civil Eng 164:184–191CrossRefGoogle Scholar
  27. 27.
    Lennon DJ, Watt E, Suckling TP (2009) Energy piles in Scotland, Presented at the International Conference on Deep Foundations on Bored and Auger Piles, Frankfurt, 15 May 2009Google Scholar
  28. 28.
    Loveridge, F. (2012) The thermal performance of foundation piles used as heat exchangers in ground energy systems, Doctoral Thesis, University of SouthamptonGoogle Scholar
  29. 29.
    Loveridge F, Powrie W (2013) Pile heat exchangers: thermal behaviour and interactions. Proc Inst Civil Eng Geotech Eng 166(2):178–196CrossRefGoogle Scholar
  30. 30.
    Loveridge F, Powrie W (2013) Temperature response functions (G-functions) for single pile heat exchangers. Energy 57:554–564CrossRefGoogle Scholar
  31. 31.
    Loveridge F, Powrie W (2014) 2D thermal resistance of pile heat exchangers. Geothermics 50:122–135CrossRefGoogle Scholar
  32. 32.
    Loveridge F, Brettman T, Olgun CG, Powrie W (2014) Assessing the applicability of thermal response testing to energy piles, In Proceedings global perspectives on the sustainable execution of foundations works, 21–23 May, Stockholm, SwedenGoogle Scholar
  33. 33.
    Mogensen P (1983) Fluid to duct wall heat transfer in duct system heat storages. In: Proceedings of International Conference On subsurface heat storage in theory and practice, Sweden, June 6–8, 1983, 652–657Google Scholar
  34. 34.
    NHBC (2010) Efficient design of piled foundations for low rise housing. National House Building Council, AmershamGoogle Scholar
  35. 35.
    Oak Ridge National Laboratory, Geothermal or ground source heat pumps, http://www.ornl.gov/sci/ees/etsd/btric/ground-source.shtml. Accessed 7th June 2013
  36. 36.
    Omer AM (2008) Ground-source heat pumps systems and applications. Renew Sustain Energy Reviews 12:344–371CrossRefGoogle Scholar
  37. 37.
    Park H, Lee S-R, Yoon S, Choi J-C (2013) Evaluation of thermal response and performance of PHC energy pile: field experiments and numerical simulation. Appl Energy 103:12–24CrossRefGoogle Scholar
  38. 38.
    Raymond J, Therrien R, Gosselin L, Lefebrve R (2011) A review of thermal response test analysis using pump test concepts. Groundwater 49(6):932–945CrossRefGoogle Scholar
  39. 39.
    Sanner B, Hellstrom G, Spitler J, Gehlin SEA (2005) Thermal response test—current status and world-wide application, In: Proceedings World Geothermal Congress, 24–29th April 2005 Antalya, Turkey. International Geothermal AssociationGoogle Scholar
  40. 40.
    Sass I, Lehr C (2011) Improvements on the thermal response test evaluation applying the cylinder source theory. In: Proceedings 36th workshop on geothermal reservoir engineering, Stanford University, Stanford, California, January 31–February 2, 2011Google Scholar
  41. 41.
    Sauer M. (2013) Evaluating improper response test data by using superposition of line source approximation, In: Proceedings of the European Geothermal Congress 2013, 3–7 June, Pisa, ItalyGoogle Scholar
  42. 42.
    Shonder JA, Beck JV (2000) A new method to determine the thermal properties of soil formations form in situ field tests, Oak Ridge National Laboratory, Report ORN/TM-2000/97, Oak Ridge, Tennessee. http://www.ornl.gov/sci/ees/etsd/btric/pdfs/com_soilproperties.pdf. Accessed 7th June 2013
  43. 43.
    SIA (2005) Utilisation de la chaleur du sol par des ouvrages de foundation et de soutenement en beton. Swiss Associations for Engineers and Architects, ZurichGoogle Scholar
  44. 44.
    Signorelli S, Bassetti S, Pahud D, Kohl T (2007) Numerical evaluation of thermal response tests. Geothermics 36:141–166CrossRefGoogle Scholar
  45. 45.
    Spitler JD, Rees S, Yavuzturk C (1999) More comments on In-situ borehole thermal conductivity testing, the source, 12 (2) March–April 1999, 4–6. http://www.hvac.okstate.edu/research/Documents/Spitler,%20Rees,%20and%20Yavuzuturk1999.pdf. Accessed 16th July 2013
  46. 46.
    Witte HJL (2013) Error analysis of thermal response tests. Energy. doi: 10.1016/j.apenergy.2012.11.060 Google Scholar
  47. 47.
    Wood CJ, Liu H, Riffat SB (2010) Comparison of a modelled and field tested piled ground heat exchanger system for a residential building and the simulated effect of assisted ground heat recharge. Int J Low Carbon Technol 5:137–143CrossRefGoogle Scholar
  48. 48.
    Yang W, Shi M, Liu G, Chen Z (2009) A two region simulation model of vertical U-tube ground heat exchangers and its experimental validation. Appl Energy 86:2005–2012CrossRefGoogle Scholar
  49. 49.
    Yavuzturk C, Spitler J (2001) Field validation of a short timestep model for vertical ground loop heat exchangers. ASHRA Trans 107(1):617–625Google Scholar
  50. 50.
    Yu X, Zhang Y, Deng N, Wang J, Zhang D, Wang J (2013) Thermal response test and numerical analysis based on two models for ground-source heat pump system. Energy Build 66:657–666CrossRefGoogle Scholar
  51. 51.
    Zervantonakis IK, Reuss M (2006) Quality requirements of a thermal response test. In: Proceedings of 10th International Conference on Thermal Energy Storage, Ecostock 06, Richard Stockton College, New Jersey, USA, 31 May–2 June 2006Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • Fleur Loveridge
    • 1
    Email author
  • William Powrie
    • 1
  • Duncan Nicholson
    • 2
  1. 1.Faculty of Engineering and the EnvironmentUniversity of SouthamptonHighfield, SouthamptonUK
  2. 2.ArupLondonUK

Personalised recommendations