Full-scale model to predict borehole fluid temperature with groundwater advection

Abstract

Ground source heat pump (GSHP) system is one of the major techniques that utilize shallow geothermal energy and borehole heat exchangers (BHEs) is the key component in GSHP system. Although most proposed analytical models for the thermal analysis of vertical BHEs take into account of the effects of either groundwater flow or axial heat conduction in the soil, the time scale of heat transfer in the BHEs is not well treated. In this study, an analytical full-scale model was developed to efficiently include the effects of the coupled transient heat transfer in the borehole, the axial heat conduction along the borehole and the effect of horizontal flow of groundwater. Results derived from the new model were compared with solutions of other traditional analytical and numerical models with the same configuration. The impacts of axial heat transfer and groundwater flow on the thermal response in the full time scale were also analyzed based on the proposed model.