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Prediction of Ground Thermal Properties from Thermal Response Test

현장 열응답 시험을 통한 지중 열물성 추정

  • Yoon, Seok (Radioactive Waste Disposal Research Division, KAERI) ;
  • Lee, Seung-Rae (Dept. of Civil and Environmental Eng., KAIST) ;
  • Kim, Young-Sang (Dept. of Marine and Civil Eng., Chunnam National Univ.) ;
  • Kim, Geon-Young (Radioactive Waste Disposal Research Division, KAERI) ;
  • Kim, Kyungsu (Radioactive Waste Disposal Research Division, KAERI)
  • 윤석 (한국원자력연구원 방사성폐기물처분연구부) ;
  • 이승래 (KAIST 건설및환경공학과) ;
  • 김영상 (전남대학교 해양토목공학과) ;
  • 김건영 (한국원자력연구원 방사성폐기물처분연구부) ;
  • 김경수 (한국원자력연구원 방사성폐기물처분연구부)
  • Received : 2016.04.04
  • Accepted : 2016.06.21
  • Published : 2016.07.31

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.

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.

Keywords

Acknowledgement

Supported by : 한국연구재단

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