Effects of the geothermal load on the ground temperature recovery in a ground heat exchanger

Abstract

The effects of the geothermal load on the ground temperature recovery in a ground heat exchanger (GHE) were investigated. A three-dimensional equivalent transient GHE analysis model was developed and validated against measured thermal response test (TRT) data and sandbox reference dataset. The effects of amount of geothermal load, duration of the recovery time per day, and daily geothermal load pattern on the ground temperature recovery were examined. The results showed that decreasing the amount of geothermal load and increasing the recovery time can improve the ground temperature recovery. However, there is little correlation between the daily geothermal load pattern and ground temperature recovery. The effects of the geothermal load on ground temperature recovery were also analyzed under different soil thermal conductivity conditions. The duration of the recovery time significantly influences the ground temperature recovery at low soil thermal conductivity. These results demonstrate the importance of considering the recovery time in the GHEs design stage to reduce the borehole length.