Effect of Some Parameters on Ground Effective Thermal Conductivity

지중열교환기 설치 조건이 지중 유효 열전도도에 미치는 영향

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.