In-Situ Thermal Response Test for Closed-Loop Vertical Ground Heat Exchanger in Shanghai, China

Ground source heat pump (GSHP) systems exchange heat with the ground, often through a closed-loop, vertical, borehole heat exchanger (BHE). The performance of the BHE depends on the thermal properties of the ground formation, as well as soil or backfill in the borehole. The design and economic probability of GSHP systems need the thermal conductivity of geological structure and thermal resistance of BHE. Thermal response test (TRT) method allows the in-situ determination of the thermal conductivity (λ) of the ground formation in the vicinity of a BHE, as well as the effective thermal resistance (Rb) of this latter. Thermal properties measured in laboratory experiments do not comply with data of in-situ conditions. The present article describes the results of thermal properties of the BHE whose depth is 80m in Qingpu District, Shanghai, China. As shown in these results, λ and Rb of borehole are determined as 1.97 W·m^-1·K^-1and 0.129 (m·K·W^-1) respectively.