Thermal resistance and capacity model for standing column wells operating under a bleed control

A fully coupled multiphysics model involving heat transfer and groundwater flow within a standing column well and its surrounding ground was modeled by means of a thermal resistance and capacity network coupled to an analytical solution. The transient groundwater velocity field and aquifer drawdown are addressed by applying a temporal superposition technique to the so-called Theis analytical equation. The heat pumps are integrated into the model, thereby allowing the effect of its entering water temperature on its capacity and coefficient of performance to be accounted for. To increase the flexibility of the approach, a three-level bleed control and an on-off sequence is included in the model, in order to allow the simulation of the dynamics of a system operation. The results show that the model developed in this paper is consistent with numerical reference solutions.