| Title |
Evaluation of Effective Thermal Conductivity and Thermal Resistance in Ground Heat Exchanger Boreholes |
| Keywords |
Effective thermal conductivity ; 유효 열전도도 ; Effective borehole thermal resistance ; 보어홀 유효 열저항 ; In-situ thermal response test ; 현장 열응답 시험 ; Parameter estimation model ; 변수 평가 모델 ; Formation ; 그라우트/토양 혼합층 |
| Abstract |
The objective of this study is to determine the effective thermal conductivity and thermal resistance values in test boreholes with three different fill materials. To evaluate these heat transfer properties, in-situ tests on four vertical boreholes were conducted by adding a monitored amount of heat to water over various test lengths. Two parameter estimation models, line-source and numerical one-dimensional models, for evaluation of thermal response test data were compared when applied on the same four data sets. Results show that the average thermal conductivity deviation between measured data and these two models is in the range of 3.03% to 4.45%. The effect of increasing grout thermal conductivity from 1.34 to 1.82 W/m℃ resulted in overall increases in effective formation thermal conductivity by 11.1% to 51.9% and reductions in borehole thermal resistance by 11.6% to 26.1%. |