Journal of the Korean Society for Geothermal and Hydrothermal Energy (한국지열·수열에너지학회논문집)

Korean Society for Geothermal and Hydrothermal Energy (한국지열·수열에너지학회)
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Thermal conductivity and viscosity of graphite-added bentonite grout for backfilling ground heat exchanger

지중 열교환기용 뒤채움재로서 흑연을 첨가한 벤토나이트 그라우트재의 열전도도 및 점도 특성

  • Lee, Chul-Ho (School of Civil, Environmental and Architectural Engineering, Korea University) ;
  • Lee, Kang-Ja (School of Civil, Environmental and Architectural Engineering, Korea University) ;
  • Choi, Hang-Seok (School of Civil, Environmental and Architectural Engineering, Korea University) ;
  • Choi, Hyo-Pum (Research&Development Institute, Kunhwa Co., Ltd.)
  • 이철호 (고려대학교 건축.사회환경공학부) ;
  • 이강자 (고려대학교 건축.사회환경공학부) ;
  • 최항석 (고려대학교 건축.사회환경공학부) ;
  • 최효범 ((주) 건화 기술연구소)
  • Published : 2009.06.01
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Abstract

Bentonite-based grouting has been usually used for sealing a borehole installed for a closed-loop vertical ground heat exchanger in a geothermal heat pump system (GHP) because of its high swelling potential and low hydraulic conductivity. The bentonite-based grout, however, has relatively lower thermal conductivity than that of ground formation. Accordingly, it is common to add some additives such as silica sand into the bentonite-based grout for enhancing heat transfer. In this study, graphite is adapted to substitute silica sand as an addictive because graphite has very high thermal conductivity. The effect of graphite on the thermal conductivity of bentonite-based grouts has been quantitatively evaluated for seven bentonite grouts from different product sources. In addition, the viscosity of graphite-added bentonite grout was measured to evaluate the field pumpability of the grout.

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