지중 열교환기용 벤토나이트 뒤채움재의 화학적, 물리적 영향 요소에 관한 연구Chemical and Physical Influence Factors on Performance of Bentonite Grouts for Backfilling Ground Heat Exchanger
- Other Titles
- Chemical and Physical Influence Factors on Performance of Bentonite Grouts for Backfilling Ground Heat Exchanger
- Authors
- 이철호; 위지혜; 박문서; 최항석; 손병후
- Issue Date
- 2010
- Publisher
- 한국지반공학회
- Keywords
- Bentonite grout; Ground heat exchanger; Segregation effect; Thermal conductivity; Viscosity; Bentonite grout; Ground heat exchanger; Segregation effect; Thermal conductivity; Viscosity
- Citation
- 한국지반공학회논문집, v.26, no.12, pp.19 - 30
- Indexed
- KCI
- Journal Title
- 한국지반공학회논문집
- Volume
- 26
- Number
- 12
- Start Page
- 19
- End Page
- 30
- URI
- https://scholar.korea.ac.kr/handle/2021.sw.korea/117643
- ISSN
- 1229-2427
- Abstract
- Bentonite-based grout has been widely used to seal a borehole constructed 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. Three types of bentonites were compared one another in terms of viscosity and thermal conductivity in this paper. The viscosity and thermal conductivity of the grouts with bentonite contents of 5%, 10%, 15%, 20% and 25% by weight were examined to take into account a variable water content of bentonite grout depending on field conditions. To evaluate the effect of salinity (i.e., concentration of NaCl : 0.1M, 0.25M, and 0.5M) on swelling potential of the bentonite-based grouts, a series of volume reduction tests were performed. In addition, if the viscosity of bentonite-water mixture is relatively low, particle segregation can occur. To examine the segregation phenomenon, the degree of segregation has been evaluated for the bentonite grouts especially in case of relatively low viscosity. From the experimental results, it is found that (1) the viscosity of the bentonite mixture increased with time and/or with increasing the mixing ratio. However, the thermal conductivity of the bentonite mixture did not increase with time but increased with increasing the mixing ratio; (2) If bentonite grout has a relatively high swelling index, the volume reduction ratio in the saline condition will be low; (3) The additive, such as a silica sand, can settle down on the bottom of the borehole if the bentonite has a very low viscosity. Consequently, the thermal conductivity of the upper portion of the ground heat exchanger will be much smaller than that of the lower portion.
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Collections - College of Engineering > School of Civil, Environmental and Architectural Engineering > 1. Journal Articles
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