Numerical simulation and analysis for the U-tube heat exchanger of ground source heat pump

In this paper, a three-dimensional numerical heat transfer model of the vertical U-tube is established using FLUENT software to research on its unsteady fluid-structure heat transfer process in order to better simulate the heat transfer area of the underground pipes in ground source heat pump system. In winter, the simulation results coincide with the experimental dates. In addition, this paper also analyzes the effects of the flow rate within the pipe, the thermal conductivity of grout, the shank spacing of U-tube and the borehole depth on the heat transfer rate. The simulation results show that the heat transfer of underground pipe per meter is proportional to the flow rate within the pipe, the thermal conductivity of grout and the shank spacing of U-tube, while it has an inverse relationship with the borehole depth.