A model of groundwater seepage and heat transfer for single-well ground source heat pump systems

In China, for the limitation of land, many buildings intending to utilize ground source heat pump systems install "single-well" systems, which drill only one well for both the pumping and reinjection of the groundwater. A model of groundwater seepage and heat transfer for single-well ground source heat pump systems has been established and validated against the experiment conducted in Denmark. In a unitary homogenous confined aquifer, the analytic seepage solution has been derived. Moreover, equations of steady drawdown, seepage velocity, quasi-steady time and hydraulic effective radius are achieved. Results show that groundwater seepage can achieve steady state quickly. In addition, the thermal performance of groundwater and aquifer on a case study in Beijing, China has been simulated. The simulation indicates that the large thermal effective radius (far to 40 m), which is much larger than that of ground-coupled heat pump, makes one single-well accommodate large space heating and cooling loads.