Evaluation of Ground Effective Thermal Conductivity and Borehole Effective Thermal Resistance from Simple Line-Source Model

단순 선형열원 모델을 이용한 지중 유효 열전도도와 보어홀 유효 열저항 산정

  • Sohn, Byong-Hu (Fire & Engineering Services Research Department, KICT)
  • 손병후 (한국건설기술연구원 화재 설비.연구부)
  • Published : 2007.07.10


The design of a ground-source heat pump system includes specifications for a ground loop heat exchanger where the heat transfer rate depends on the effective thermal conductivity of the ground and the effective thermal resistance of the borehole. To evaluate these heat transfer properties, in-situ thermal response tests on four vertical test boreholes with different grouting materials were conducted by adding a monitored amount of heat to circulating water. The line-source method is applied to the temperature rise in an in-situ test and extended to also give an estimate of borehole effective thermal resistance. The effect of increasing thermal conductivity of the grouting materials from 0.818 to $1.104W/m^{\circ}C$ resulted in overall increases in effective thermal conductivity by 15.8 to 56.3% and reductions in effective thermal resistance by 13.0 to 31.1%.



  1. Mogensen, P., 1983, Fluid to duct wall heat transfer in duct system storages, Proceedings of the International Conference on Subsurface Heat Storage in Theory and Practice. Swedish Council for Building Research, June pp. 6-8
  2. Spilker, E. H., 1998, Ground-coupled heat pump loop design using thermal conductivity testing and the effect of different backfill materials on vertical bore length, ASHRAE Transactions, Vol. 104, pp. 775-779
  3. Zhang, Q. and Murvhy, W. E., 2000, Measurement of thermal conductivity for three borehole fill materials used for GSHP, ASHRAE Transactions, Vol.106, pp. 434-441
  4. Smith, M. D. and Perry, R. L., 1999, Borehole grouting: field studies and thermal perfonnance testing, ASHRAE Transactions, Vol. 105, pp. 451-457
  5. Shonder, J. A. and Beck, J. V., 2000, Field test of a new method for determining soil formation thermal conductivity and borehole resistance, ASHRAE Transactions, Vol. 106, pp. 843-850
  6. Martin, C. A. and Kavanaugh, S. P., 2002, Ground thermal conductivity testing control site analysis, ASHRAE Transactions, Vol. 108, pp. 945-952
  7. Beier, R. A. and Smith, M. D., 2003, Minimum duration of in-situ tests on vertical boreholes, ASHRAE Transactions, Vol. 109, pp. 475-486
  8. Lim, H.J., Kong, H.J., Song, Y. S. and Park, S. K, 2005, Thermal conductivity measurement of grouting materials for geothermal heat exchanger, Korean Journal of Air-Conditioning and Refrigeration Engineering, Vol. 17, No. 4, pp. 364-369
  9. Lee, S. K, Woo, J. S., Ro, J. G. and Kim, D. K., 2006, A study on the estimation of soil formation thermal conductivities and borehole resistances with one-dimensional numerical model and in-situ field tests, Korean Journal of Air-Conditioning and Refrigeration Engineering, Vol. 18, No. 10, pp. 783-790
  10. Sohn, B. H., Shin, H. J. and An, H.J., 2005, Evaluation of thermal conductivity for grout/soil formation using thermal response test and parameter estimation models, Korean Journal of Air-Conditioning and Refrigeration Engineering, Vol. 17, No. 2, pp. 173-182
  11. Sohn, B. H., Shin, H. J. and Park, S. K., 2005, Evaluation of effective thermal conductivity and thermal resistance in ground heat exchanger boreholes, Korean Journal of Air-Conditioning and Refrigeration Engineering, Vol. 17, No. 8, pp. 695-703
  12. Kline, S.J., 1985, The purpose of uncertainty analysis, Journal of Fluids Engineering, Vol. 107, pp. 153-160 https://doi.org/10.1115/1.3242449
  13. Carslaw, H. S. and Jaeger, J. C., 1947, Conduction of Heat in Solids, 2nd ed., Oxford University Press
  14. Ingersoll, L. R. and Plass, H. J., 1948, Theory of the ground pipe heat source for the heat pump, Heating, Piping & Air Conditioning, July, pp. 119-122
  15. Spitler, J. D., 1999. GLHEPRO 3.0 for Windows Users Guide, School of Mechanical and Aerospace Engineering, Oklahoma State University
  16. Gaia Geothermal, 2003, Ground Loop Design Version 2.7 for Windows, Gaia Geothermal
  17. IGSHPA, 2000, Grouting for Vertical Geothermal Heat Pump Systems: Engineering Design and Field Procedures Manual, International Ground Source Heat Pump Association, Still water, Oklahoma
  18. Remund, C. P., 1999, Borehole thennal resistance: laboratory and field studies, ASHRAE Transactions, Vol. 105, pp. 439-445
  19. Salomone, L. A. and Marlowe, J. I., 1989, Soil and Rock Classification for the Design of Ground-Coupled Heat Pump Systems: Field Manual, Special Report(EPRI CU-6600), Electric Power Research Institute