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2016 Vol.32, Issue 7
Prediction of Ground Thermal Properties from Thermal Response Test

현장 열응답 시험을 통한 지중 열물성 추정

Seok Yoon1
,
Seung-Rae Lee2*
,
Young-Sang Kim3
,
Geon-Young Kim4
,
Kyungsu Kim5
윤 석1
,
이 승래2*
,
김 영상3
,
김 건영4
,
김 경수5
1Member, Senior Researcher, Radioactive Waste Disposal Research Division, KAERI
2Member, Prof., Dept. of Civil and Environmental Eng., KAIST
3Member, Dept. of Marine and Civil Eng., Chunnam National Univ.
4Principal Researcher, Radioactive Waste Disposal Research Division, KAERI
5Principal Researcher, Radioactive Waste Disposal Research Division, KAERI
1정회원, 한국원자력연구원 방사성폐기물처분연구부 선임연구원
2정회원, KAIST 건설및환경공학과 교수
3정회원, 전남대학교 해양토목공학과 교수
4비회원, 한국원자력연구원 방사성폐기물처분연구부 책임연구원
5비회원, 한국원자력연구원 방사성폐기물처분연구부 부장, 책임연구원
*교신저자. *Corresponding Author. 
31 July 2016. pp. 5-14
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Abstract

The use of geothermal energy has increased for economically and environmentally friendly utilization, and a geothermal heat pump (GSHP) system for space heating and cooling is being used widely. As ground thermal properties such as ground thermal conductivity and ground thermal diffusivity are substantial parameters in the design of geothermal heat pump system, ground thermal conductivity should be obtained from in-situ thermal response test (TRT). This paper presents an experimental study of ground thermal properties of U and 2U type ground heat exchangers (GHEs) measured by TRTs. The U and 2U type GHEs were installed in a partially saturated dredged soil deposit, and TRTs were conducted for 48 hours. A method to derive the thermal diffusivity as well as thermal conductivity was proposed from a non-linear regression analysis. In addition, remolded soil samples from different layers were collected from the field, and soil specimens were reconstructed according to the field ground condition. Then equivalent ground thermal conductivity and ground thermal diffusivity were calculated from the lab test results and they were compared with the in-situ TRT results.

Keywords
Thermal response test
Ground thermal conductivity
Ground thermal diffusivity
Non-linear regression anlaysis

최근 들어 경제적이고 친환경적인 에너지 활용을 위하여 지열에너지의 필요성이 점차 증대되고 있다. 특히 지열히트펌프 시스템(geothermal heat pump system)으로 불리는 지열 냉난방 시스템의 적용성이 계속 확대되고 있다. 이러한 지열히트펌프 시스템에서 지반의 열전도도와 열확산계수와 같은 지중 열물성은 설계 과정에서 매우 중요한 변수이기에 현장 열응답 시험(thermal response test)을 통해 지반의 열전도도를 산출해야 한다. 본 논문에서는 U와 2U 타입의 지중 열교환기를 매립지 지반에 설치한 후 48시간 동안 현장 열응답 시험을 수행하였으며 지반의 열전도도 뿐만 아니라 지반의 열확산계수를 비선형 회귀분석을 통해 산정할 수 있는 방안을 제시하였다. 또한 지중 열교환기가 설치된 지반의 시료를 채취하여 실내 열물성 실험을 수행하였으며 이를 현장 열응답 시험을 통해 도출된 지반의 열전도도 및 열확산계수 값과 비교하였다.

References
1
1.Anthony, J. H. (2007), “Probability and Statistics for Engineers and Scientists”, Third Edition, THOMSON BROOKS/COLE.
2
2.Beck, M., Bayer, P., and Paly, M. C., Hecht-Mendez J., and Zell, A. (2013), “Geometric Arrangement and Operation Mode Adjustment in Low-enthalpy Geothermal Borehole Fields for Heating”, Energy Vol.49, pp.434-443.
3
3.Bennet, J., Claesson, J., and Hellstrom, G. (1987), “Multipole Method to Compute the Conductive Heat Flows to and between Pipes in a Composite Cylinder”, Notes on Heat Transfer, 1987:3, Lund University, Lund, Sweden.
4
4.Carslaw, H. and Jaeger, J. (1947), “Conduction of Heat in Solids”, Oxford, Claremore Press.
5
5.Gaia Geothermal. Ground Loop Design Software, GLD2012.
6
6.Ingersoll, L. R. and Zobel, O.J. (1954), “Heat Conduction with Engineering Geological and other Applications”, MC Graw-Hill, New York.
7
7.Jun, L., Xu, Z., Jun, G., and Jie, Y. (2009), “Evaluation of Heat Exchange Rate of GHE in Goethermal Heat Pump Systems”, Renewable Energy, Vol.34, pp.2898-2904.
8
8.Lee, C. H., Park, M. S., Nguyen, T. B., Shon, B., Choi, J. M., and Choi, H. S. (2012), “Performance Evaluation of Closed-loop Vertical Ground Heat Exchangers by Conducting In-situ Thermal Response Tests”, Renewable Energy, Vol.42, pp.77-83.
9
9.Lee, I. H. (2014), “Easy Flow Regression Analysis”, Hannarae Publishing Corporation.
10
10.Lee, K. (2010), “Study on Thermal Characteristics of Backfill Materials for Horizontal Ground Heat Exchanger”, Master thesis, Korea University.
11
11.Lim, H. J., Kong, H. J., Kang, S. J., and Choi, J. H. (2011), “The Effect of the Installation Condition of Ground Loop Heat Exchanger to the Thermal Conductivity and Borehole Resistance”, Korean Journal of Air-Conditioning and Refrigeration Engineering, Vol. 23, No.2, pp.95-102.
12
12.Min, H. S., Yun, T. S., and Jeong, S. S. (2011), “Effect of Group Spacing of Energy Piles on Thermal Analysis”, Journal of the Korean Geotechnical Society, Vol.27, No.8, pp.39-50.
13
13.Pahud, D., Fromentin, A., and Hubbuch, M. (1999), “Heat Exchanger Pile System for Heating and Cooling at Zürich Airport”, IEA Heat Pump Centre Newslett, Vol.17, No.1, pp.15-16.
14
14.Park, H. (2011), “Thermal Conductivities of Unsaturated Korean Weathered Granite Soils”, Master thesis, KAIST.
15
15.Park, H. K., Lee, S. R., Yoon, S., and Choi, J. C. (2013), “Evaluation of Thermal Response and Performance of PHC Energy Pile: Field Experiments and Numerical Simulation”, Applied Energy, Vol.103, pp.12-24.
16
16.Remund, C. P. (1999), “Borehole Thermal Resistance: Laboratory and Field Studies”, ASHARE CH-99-2-1.
17
17.Roque, B. T., Jose N. C., and Daniel, C. F. (2015), “How to Correct the Ambient Temperature Influence on the Thermal Response Test Results”, Applied Thermal Engineering, Vol.82, pp.39-47.
18
18.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.
19
19.Yoon, S., Lee, S. R., Kim, Y. T., and Go, G. H. (2015), “Estimation of Saturated Hydraulic Conductivity of Korean Weathered Granite Soils using a Regression Analysis”, Geomechanics and Engineering, Vol.9, No.1, pp.101-113.
20
20.Yoon, S., Lee, S. R., Kim, M. J., and Go, G. H. (2014), “Evaluation of Thermal Response Test of Energy Pie”, Journal of the Korean Geotechnical Society, Vol.30, No.4, pp.93-99.
21
21.Yoon, S., Lee, S. R., Kang, H. B., Go, G. H., Kim, M. J., and Shin, H. S. (2013), “Evaluation of Borehole Thermal Resistance in Ground Heat Exchanger”, Journal of the Korean Geotechnical Society, Vol.29, No.10, pp.49-56.
Information
  • Publisher :The Korean Geotechnical Society
  • Publisher(Ko) :한국지반공학회
  • Journal Title :Journal of the Korean Geotechnical Society
  • Journal Title(Ko) :한국지반공학회 논문집
  • Volume : 32
  • No :7
  • Pages :5-14
  • Received Date : 2016-04-14
  • Revised Date : 2016-05-23
  • Accepted Date : 2016-06-21
  • DOI :https://doi.org/10.7843/kgs.2016.32.7.5
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