Heat transfer model for a standing column well geothermal system

A coupled heat transfer model for the standing column well (SCW) of a geothermal assisted heat pump system was established based on conversion of energy. This allows investigation of the complicated heat transfer characteristics of SCW. Heat exchange between the casing of the supply pipe and the borehole wall was included in the control equations to produce a whole-field solution to the temperatures of aquifer, borehole and supply pipe. Thermal dispersion was included in the heat transfer model of the aquifer. Numerical simulations of an in-situ test of SCW were created. The simulation showed that the output of the model was sensitive to the permeability coefficient and the thermal dispersion tensor of the aquifer, with the thermal dispersion tensor highly significant. Because of this, inclusion of thermal dispersion had a significant impact on results, suggesting thermal dispersion must be included when calculating heat transfer. The simulation results showed that there was a good agreement between the temperatures of pumped groundwater predicted by the model. In tests, the error was less than ten percent. This preliminary validation shows that the coupled heat transfer model for SCW systems is accurate enough to be useful for simulations.