| Title |
Evaluation of Ground Effective Thermal Conductivity andBorehole Effective Thermal Resistance from Simple Line-Source Model |
| Keywords |
지중 유효 열전도도 ; 보어홀 유효 열저항 ; 현장 열응답 시험 ; 선형열원 모델 ; 그라우팅 재료 Ground effective thermal conductivity ; Borehole effective ther- mal resistance ; In-situ thermal response test ; Line-source model ; Grouting materials |
| Abstract |
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℃ resulted in overall increases in effective thermal conductivity by 15.8 to 56.3% and reductions in effec- tive thermal resistance by 13.0 to 31.1%. |