Research on the Utilization of Ground Heat Resource and the Numerical Simulation of the Heat Exchange of Underground U-Tube

Ground heat resource is a kind of renewable energy source, widely existing in the soil and groundwater of the shallow constant temperature layer; and its utilization has raised great attention of many countries. In this paper, the commercial CFD software is used for the research of 3D unsteady fluid-solid coupling heat exchange of underground U-tube. In order to facilitate computation, a steady computation is adopted for the flow field firstly. Then, the calculation of unsteady temperature field of fluid-solid coupling heat exchange is done. The difference of heat exchange between the multilayer soil structure and the monolayer soil structure with the soil´s physical property parameter a weighted average, is compared. In this approach, the temperature change of fluid at U-tube´s outlet, the heat exchange of fluid at different sections of the tube and its averaged heat exchange value, in various velocities of flow, are also investigated, as well as the possibility of appearing the heat short circuit. Finally, it discusses the trait of heat exchange of various sections of U-tube at different well-depth. This paper will be an essential basis for the future short-cut computation about the heat exchange of underground U-tube.