Analysis of heat transfer in a borehole heat exchanger (BHE) with the OpenGeoSys model

We simulated thermal dispersion of a borehole heat exchanger (BHE) with a thermal response test (TRT) data by using the OpenGeoSys model. The analysis of the heat transfer is critical for the design of ground source heat pump (GSHP) system because the system performance is related mostly to the geometry of BHE and the thermal properties of each material. The adapted system is double U-tube type and the borehole depth is 200 m and a model was set up according to the BHE specification in 40 x 40 m in x, y scale. Inside area of two inlet and two outlet fluid pipes, different temperature of circulation fluid were determined according to the test data. The simulated temperature variation around the well and borehole wall is compared with the temperature distribution obtained by the line source model. The differences were studied to evaluate the developed model and heat exchange rates were calculated during an operation period. As well as the heat transfer simulation by the ground water flow in fracture were conducted.