Heat Transfer Model of Geothermal Heat Exchangers Embedded in Diaphragm Walls

Abstract:

The technology of embedding absorber tubes in diaphragm walls is a new developing direction of Ground Source Heat Pump. As the diaphragm walls are located in the ground where temperature remains constant all year around, the shallow geothermal energy may be obtained for space cooling and heating by circulating the medium in absorber tubes. According to the structure and heat transfer characteristics of geothermal heat exchangers, two heat transfer models and their analytical solutions were obtained. One model is for the section over the excavation surface, and the other is for the section under the excavation surface. The models may be employed to calculate the temperature field of diaphragm walls and the surrounding soil under non-homogeneous boundary conditions and varying internal heat source. The models may also be used to optimize the system parameters, including the layout and spacing of heat exchangers, the running time of intermittent operation.