• 제목/요약/키워드: Ground effective thermal Conductivity

검색결과 8건 처리시간 0.037초

밀폐형 지중열교환기 설계를 위한 지중 유효열전도도 데이터베이스 구축 (Construction of Ground Effective Thermal Conductivity Database for Design of Closed-Loop Ground Heat Exchangers)

  • 최재호;손병후;임효재
    • 대한설비공학회:학술대회논문집
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    • 대한설비공학회 2008년도 하계학술발표대회 논문집
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    • pp.776-781
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    • 2008
  • A ground heat exchanger in a GSHP system is an important unit that determines the thermal performance of a system and its initial cost. The Size and performance of this heat exchanger is highly dependent on the thermal properties. A proper design requires certain site-specific parameters, most importantly the ground effective thermal conductivity, the borehole thermal resistance and the undisturbed ground temperature. This paper is part of a research project aiming at constructing a database of these site-specific properties, especially ground effective thermal conductivity. The objective was to develop and evaluation method, and to provide this knowledge to design engineers. To achieve these goals, thermal response tests were conducted using a testing device at nearly 150 locations in Korea. The in-situ thermal response is the temperature development over time when a known heating load imposed, e.g. by circulating a heat carrier fluid through the test exchangers. The line-source model was then applied to the response test data because of its simplicity. From the data analysis, the range of ground effective thermal conductivity at various sites is $1.5{\sim}4.0\;W$/mK. The results also show that the ground effective thermal conductivity varies with grouting materials as well as regional geological conditions and groundwater flow.

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지중열교환기 설치 조건이 지중 유효 열전도도에 미치는 영향 (Effect of Some Parameters on Ground Effective Thermal Conductivity)

  • 최재호;임효재;공형진;손병후
    • 대한설비공학회:학술대회논문집
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    • 대한설비공학회 2008년도 동계학술발표대회 논문집
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    • pp.33-38
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    • 2008
  • A ground-loop heat exchanger in a ground source heat pump system is an important unit that determines the thermal performance of a system and its initial cost. The Size and performance of this heat exchanger is highly dependent on ground thermal properties. A proper design requires certain site-specific parameters, most importantly the ground effective thermal conductivity, the borehole thermal resistance and the undisturbed ground temperature. This study was performed to investigate the effect of some parameters such as borehole lengths, various grouting materials and U-tube configurations on ground effective thermal conductivity. In this study, thermal response tests were conducted using a testing device with 9-different ground-loop heat exchangers. From the experimental results, the length of ground-loop heat exchanger affects to the effective thermal conductivity. Among the various grouting materials, the bentonite-based grout with silica sand shows the largest thermal conductivity value.

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지중열교환기 설치 조건이 지중 유효 열전도도와 보어홀 열저항에 미치는 영향 (The Effects of the Installation Conditions of Ground Loop Heat Exchanger to the Thermal Conductivity and Borehole Resistance)

  • 임효재;공형진;강성재;최재호
    • 설비공학논문집
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    • 제23권2호
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    • pp.95-102
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    • 2011
  • A ground loop heat exchanger in a ground source heat pump system is an important unit that determines the thermal performance of a system and its initial cost. A proper design requires certain site specific parameters, most importantly the ground effective thermal conductivity, the borehole thermal resistance and the undisturbed ground temperature. This study was performed to investigate the effect of some parameters such as borehole lengths, various grouting materials and U tube configurations on ground effective thermal conductivity and borehole thermal resistance. In this study, thermal response tests were conducted using a testing device to 9 different ground loop heat exchangers. From the experimental results, the length of ground loop heat exchanger affects to the effective thermal conductivity. The results of this experiment shows that higher thermal conductivity of grouting materials leads to the increase effective thermal conductivity from 22 to 32%. Also, mounting spacers have increased by 14%.

지중열교환기 설치 조건이 지중 유효 열전도도에 미치는 영향에 관한 실험적 연구 (An Experimental Study on the Effect of Ground Heat Exchanger to the Overall Thermal Conductivity)

  • 공형진;임효재;최재호;손병후
    • 대한설비공학회:학술대회논문집
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    • 대한설비공학회 2009년도 하계학술발표대회 논문집
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    • pp.45-51
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    • 2009
  • A ground-loop heat exchanger in a ground source heat pump system is an important unit that determines the thermal performance of a system and its initial cost. The size and performance of this heat exchanger is highly dependent on ground thermal properties. A proper design requires certain site-specific parameters, most importantly the ground effective thermal conductivity, the borehole thermal resistance and the undisturbed ground temperature. This study was performed to investigate the effect of some parameters such as borehole lengths, various grouting materials and U-tube configurations on ground effective thermal conductivity. In this study, thermal response tests were conducted using a testing device with 9-different ground-loop heat exchangers. From the experimental results, the length of ground-loop heat exchanger affects to the effective thermal conductivity. Among the various grouting materials, the bentonite-based grout with silica sand shows the largest thermal conductivity value.

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그라우팅 재료가 지중 유효열전도도에 미치는 영향 (Effect of Grouting Materials on Ground Effective Thermal Conductivity)

  • 손병후
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2007년도 춘계학술대회B
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    • pp.3371-3376
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    • 2007
  • The design of a ground-source heat pump system includes specifications for a ground loop heat exchanger where the heat transfer rate depends on the thermal conductivity of the ground. To evaluate this heat transfer property, in-situ thermal response tests on four vertical test boreholes with different grouting materials were conducted by adding a monitored amount of heat to water over various test lengths. By measuring the water temperatures entering and exiting the loop, water flow rate, and heat load, effective thermal conductivity values of the ground were determined. The effect of increasing thermal conductivity of grouting materials from 0.82 to 1.05 W/m$^{\circ}C$ resulted in overall increases in effective ground thermal conductivity by 25.8% to 69.5%.

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단순 선형열원 모델을 이용한 지중 유효 열전도도와 보어홀 유효 열저항 산정 (Evaluation of Ground Effective Thermal Conductivity and Borehole Effective Thermal Resistance from Simple Line-Source Model)

  • 손병후
    • 설비공학논문집
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    • 제19권7호
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    • pp.512-520
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    • 2007
  • The design of a ground-source heat pump system includes specifications for a ground loop heat exchanger where the heat transfer rate depends on the effective thermal conductivity of the ground and the effective thermal resistance of the borehole. To evaluate these heat transfer properties, in-situ thermal response tests on four vertical test boreholes with different grouting materials were conducted by adding a monitored amount of heat to circulating water. The line-source method is applied to the temperature rise in an in-situ test and extended to also give an estimate of borehole effective thermal resistance. The effect of increasing thermal conductivity of the grouting materials from 0.818 to $1.104W/m^{\circ}C$ resulted in overall increases in effective thermal conductivity by 15.8 to 56.3% and reductions in effective thermal resistance by 13.0 to 31.1%.

저심도 대구경 지중열교환기의 설치조건에 따른 성능 연구 (Performance Evaluation of Large Borehole Ground-Loop Heat Exchanger)

  • 유규상;박일문;최재호;신현준
    • 대한설비공학회:학술대회논문집
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    • 대한설비공학회 2009년도 하계학술발표대회 논문집
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    • pp.58-63
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    • 2009
  • A ground-loop heat exchanger for the ground source heat pump system is the core equipment determining the thermal performance and initial cost of the system. The size and performance of the heat exchanger is highly dependent on the ground thermal properties - the ground effective thermal conductivity, the borehole thermal resistance and the undisturbed ground temperature. Nowadays, precast concrete piles using steel reinforced precast concrete piles - energy piles - are used to reduce the installing cost of the ground-loop heat exchanger. We were carried out some tests to investigate the effects of some parameters such as borehole length, grouting materials and U-tube configuration of the energy piles. 4 concrete piles, each measuring $250mm{\sim}400mm$ in diameter and approx. 10m in length, and rigged with single spiral and 3 U-tube loop of $16mm{\times}2.3mm$ PB piping. The thermal response tests were conducted using a testing device for 4-different ground-loop heat exchangers. During the heating period, the energy piles absorb the heat of 0.89kW to 1.37kW.

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지중 유효 열전도도의 지역별 분포 (A Study on Regional Distribution of the Ground Effective Thermal Conductivity)

  • 공형진;권순기;지승규
    • 대한기계학회논문집 C: 기술과 교육
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    • 제4권1호
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    • pp.43-47
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    • 2016
  • 지열 히트펌프 시스템은 환경 친화적이고 에너지 절감 시스템으로 알려져 있다. 특히 지중 열교환기는 초기투자비와 시스템 성능을 결정하는 매우 중요한 요소다. 수직형 지열 시스템 설계를 위해서는 현장 열응답 테스트를 통해 지중 유효 열저항을 고려해야 한다. 본 연구에서는 지열이용검토서를 통해 접수된 전국의 지중 열전도도를 지역별로 분석하였다. 전국 평균 지중 열전도도는 2.56 W/mK로 분석되었다. 지중 열전도도가 가장 높은 지역은 서울로 평균 2.68 W/mK이고, 가장 낮은 지역은 부산으로 2.28 W/mK다. 또한 해안을 접하고 있는 지역의 열전도도는 전국 평균에 비해 약 30% 낮다.