Journal of the Korean Geotechnical Society (한국지반공학회논문집)

Korean Geotechnical Society (한국지반공학회)
권호 표지
DOI QR코드

DOI QR Code

Study on Thermal Behavior and Design Method for Coil-type PHC Energy Pile

코일형 PHC 에너지파일의 열적 거동 및 설계법에 관한 연구

  • Park, Sangwoo (Graduate Student, School of Civil, Environmental and Architectural Engrg., Korea Univ.) ;
  • Sohn, Jeong-Rak (Korea Land & Housing Corporation) ;
  • Park, Yong-Boo (Korea Land & Housing Corporation) ;
  • Ryu, Hyung-Kyou (Technology Research&Development Institute, DAELIM Industrial Corporation) ;
  • Choi, Hangseok (Graduate Student, School of Civil, Environmental and Architectural Engrg., Korea Univ.)
  • Received : 2013.01.24
  • Accepted : 2013.07.30
  • Published : 2013.08.31
Download PDF
⟨ Previous Next ⟩

Abstract

An energy pile encases heat exchange pipes to exchange thermal energy with the surrounding ground formation by circulating working fluid through the pipes. An energy pile has many advantages in terms of economic feasibility and constructability over conventional Ground Heat Exchangers (GHEXs). In this paper, a coil-type PHC energy pile was constructed in a test bed and its thermal performance was experimentally and numerically evaluated to make a preliminary design. An in-situ thermal response test (TRT) was performed on the coil-type PHC energy pile and its results were compared with the solid cylinder source model presented by Man et al. (2010). In addition, a CFD numerical analysis using FLUNET was carried out to back-analyze the thermal conductivity of the ground formation from the Ttype PHC energy RT result. To study effects of a coil pitch of the coil-type heat exchange pipe, a thermal interference between the heat exchange pipes in PHC energy piles was parametrically studied by performing the CFD numerical analysis, then the effect of the coil pitch on thermal performance and efficiency of heat exchange were evaluated. Finally, an equivalent heat exchange efficiency factor for the coil-type PHC energy pile in comparison with a common multiple U-type PHC energy pile was obtained to facilitate a preliminary design method for the coil-type PHC energy pile by adopting the PILESIM2 program.

에너지파일은 말뚝 내부에 열교환을 위한 순환파이프를 설치하여 파이프 내에 열전달 유체를 순환시킴으로써 주변 지반의 열에너지와 말뚝 간의 열교환을 가능하게 한 구조물이다. 에너지파일은 기존의 지중 열교환기와 비교하여 경제적, 시공적인 측면에서 많은 장점을 가지고 있다. 본 논문에서는 코일형 PHC 에너지파일을 시공하여 그 열적거동을 실험 및 수치해석을 통하여 평가하였으며, 해당 에너지파일의 예비설계를 수행하였다. 현장 시공된 코일형 PHC 에너지파일에 대한 현장 열응답시험(thermal response test, TRT)를 실시하고, 이 결과를 Man et al.(2010)이 제안한 개선된 원통형 열원 모델(solid cylinder source model) 결과와 비교하였다. 또한 현장 열응답 시험 결과를 FLUENT를 이용한 전산유체(computational fluid dynamics, CFD) 수치해석을 통해 모사함으로써, 대상 지반의 열전도도를 역해석을 통해 산정하였다. 코일형 PHC 에너지파일에 설치된 코일형 열교환 파이프의 파이프 루프 간 간격에 따른 열간섭을 평가하기 위하여 코일피치에 변화를 주며 수치해석을 수행하였으며, 결과를 통해 코일피치에 따른 에너지파일의 열거동 및 열교환 효율을 평가하였다. 마지막으로 수치해석을 통해 코일형 PHC 에너지파일과 일반적인 복합 U-형 열교환 파이프가 삽입된 PHC 에너지파일 간의 열교환 효율을 비교하여 코일형 PHC 에너지파일의 등가 열교환율(또는 등가 환산계수)을 제시하였고, 이를 PILESIM2를 이용한 설계 알고리즘에 적용함으로써 해당 에너지파일의 예비설계를 수행하였다.

Keywords

References

  1. 민선홍 (2011), 현장타설 에너지파일 설계를 위한 등가 열교환율에 관한 연구, 석사학위논문, 고려대학교.
  2. 신에너지 및 재생에너지 개발.이용.보급 촉진법, 법률 제 10445호.
  3. Baek, S-K (2004), Study on ground-coupled heat pump system using hollow piles, Ph.D. Thesis, Busan University, Korea.
  4. Brandl, H. (2006), "Energy foundation and other thermo-active ground structures", Geotechnique, Vol.56, No.2, pp.81-122. https://doi.org/10.1680/geot.2006.56.2.81
  5. Carslaw, S. H. and Jaeger, J. C. (1959), Conduction of heat in solids, 2nd ed., Oxford Science Publication.
  6. Cui, P., Li, X., Man, Y., and Fang, Z. (2011), "Heat transfer analysis of pile geothermal heat exchangers with spiral coils", Applied Energy, Vol.88, No.11, pp.4113-4119. https://doi.org/10.1016/j.apenergy.2011.03.045
  7. Department Of Energy, DOE (2001), "Ground-source heat pumps applied to federal facilities-second edition", Federal Energy Management Program, DOE/EE-0245(PNNL-13534), US Department of Energy
  8. Engineering tool box (2005), Engineeringtoolbox.com
  9. Environmental Protection Agency, EPA (1993), "Space Conditioning : The Next Frontier, Office of Air and Radiation", 403-R-93-0044 (4/93), Energy Protection Agency, Washington D.C.
  10. Gao, J., Zhang, X., Liu, J., Li, K., and Yang, J. (2008), "Numerical and experimental assessment of thermal performance of vertical energy piles", An application, Applied Energy, Vol.85, pp.901-910. https://doi.org/10.1016/j.apenergy.2008.02.010
  11. Ingersoll, L. R., Zobel, O. J., and Ingersoll, A. C. (1954), Heat Conduction with engineering and geological application, McGraw-Hill, New York.
  12. Jeong, S., Song, J., Min, H., and Lee, S. (2010), "Thermal influence factors of energy pile", Journal of the Korean Society of Civil Engineers (KSCE), Vol.30, No.6C, pp.231-239.
  13. Jun, L., Zhang, X., Gao, J., and Yang, J. (2009), "Evaluation of heat exchange rate of GHW in geothermal heat pump system", Renewable Energy, Vol.34, pp.2898-2904. https://doi.org/10.1016/j.renene.2009.04.009
  14. Kavanaugh, S.P. and Rafferty, K. (1997), "Ground-Source Heat Pumps - Design of Geothermal Systems for Commercial and Institutional Buildings", American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE), Atlanta
  15. Lee, C. (2012), Performance of ground heat exchangers for civil infrastructures, Ph.D. Thesis, Korea University, Korea.
  16. Lee, C., Park, M., Min, S., Choi, H., and Sohn. B. (2010), "Evaluation of Performance of Grouts and Pipe sections for Close-Loop Vertical Ground Heat Exchanger by In-situ Thermal Response test", Jounral of Korean Geotechnical Society (KGS), Vol.26, No.7, pp.93-106.
  17. Man, L., Yang, H., Diao, N., Liu, J., and Fang, J. (2010), "A new model and analytical solutions for borehole and pile ground heat exchangers", International Journal of Heat and Mass Transfer, Vol.53, pp.2593-2061. https://doi.org/10.1016/j.ijheatmasstransfer.2010.03.001
  18. Min, S., Park, S., Koh, H., Yoo, J., Jung, K., and Choi, H. (2012), "Study on equivalent heat exchange efficiency and design method for cast-in-place energy pile", Proceedings of 2012 KGS Spring Conference, Korean Geotechnical Society (KGS), pp.655-666.
  19. Nam, Y., Hwang, S., and Ooka, R. (2007), "Geothermal heat pump system using foundation pile structures", Journal of Korea Society of Geothermal Energy Engineers, Vol.3, No.1, pp.51-60.
  20. Nam, Y., Ooka, R., and Hwang, S. (2008), "Development of a numerical model to predict heat exchange rates for a ground source heat pump system", Energy and Building, Vol.40, pp.2113-2140.
  21. Nam, Y. and Ooka, R. (2011), "Development of potential map for ground and groundwater heat pump systems and the application to tokyo", Energy and Building, Vol.43, pp.677-685. https://doi.org/10.1016/j.enbuild.2010.11.011
  22. Pahud, D. and Hubbuck, M. (2007), "Measured thermal performances of the energy pile system of the duck midfield as Zurick Airport", Proceedings European Geothermal Congress 2007, Unterhaching, Germany, 30 May-1 June.
  23. Park, Y-B, Park, J-B, and Lim, H-S (2007), "Construction method of ground heat exchanger using energy pile in ground source heat system", KSCE magazine, Vol.55, No.7, pp.41-46.
  24. Ryu, H-K (2008), "Development and performance evaluation of ground heat exchanger utilizing PHC pile foundation of building", Journal of the Korean Solar Energy Society, Vol.28, No.5, pp.56-64.
  25. Salomone, L. A. and Marlowe, J. I. (1989), "Soil and rock classification according to thermal conductivity : Design of groundcoupled heat pump systems : Final report", Electric Power Research Inst.(EPRI), EPRI-CU-6482.
  26. Sharqawy, M. H., Mokheimer, E. M., Habib, M. A., Badr, H. M., Said, N. A., and Al-Shayea, S. A. (2009), "Energy, energy and uncertainty analyses of the thermal response test for a ground heat exchanger", International Journal of Energy Research, Vol.33, pp. 582-592. https://doi.org/10.1002/er.1496
  27. Wagner, R. and Clauser, C. (2005), "Evaluating thermal response tests using parameter estimation for thermal conductivity and thermal capacity", Journal of Geophysics and Engineering, Vol.2, pp.349-356. https://doi.org/10.1088/1742-2132/2/4/S08
  28. Yavuzturk, C., Spitler, J. D., and Rees, S. J. (1999), "A transient two-dimensional finite volume model for simulation of vertical U-tube ground heat exchanger", ASHRAE Transactions, Vol.105, No.2, pp.465-474.
  29. Yoon, S., Go, G-H, Park, H-K, Park, S., Lee, S-R, Cho, K-J, and Song, C-Y (2012), "Thermal conductivity estimate of ground using energy piles", Journal of Korea Society of Geothermal Energy Engineers, Vol.8, No.4, pp.8-16.

Cited by

  1. 에너지 파일의 현장 열응답 시험에 관한 연구 vol.30, pp.4, 2013, https://doi.org/10.7843/kgs.2014.30.4.93