Thermal response test for ground source heat pump based on constant temperature and heat-flux methods

TRT has been a useful and consolidated tool to determine the ground thermal properties for GSHP. In this paper, six TRTs were carried out to analyze the heat transfer performance of GHE based on constant temperature and heat-flux methods. Vertical temperatures were measured using temperature sensors installed along GHE pipes. A multi-layer cylindrical source model was developed to estimate thermal conductivity distributions in the ground around GHE based on the vertical temperatures. The results showed that the constant temperature method had many advantages in shortening test period, operating stability and test accuracy compared with the traditional constant heat-flux method. The estimated thermal conductivities obtained based on the multi-layer cylindrical source model were consistent with the geological conditions and groundwater aquifer.