Analysis of Influences of Soil Characteristics on the Underground Heat Exchanger With a Novel Heat and Mass Transfer Model

In this paper, a novel heat and mass transfer model was used to simulate the temperature field of both the U-tube heat exchanger and soil around it. Beside two-dimensional N-S equations were solved to consider the seepage of groundwater, an energy equation coupling thermal conduction and groundwater advection was enclosed in the model as well. The energy equation was built according to the real conditions of the U-tube and seepage flow in the soil. Through analyzing the simulation results, the effects of groundwater seepage to the heat transfer process and thermal short-circuiting among U-tube legs are obtained. The influences of soil type, soil physical aspects and backfill on the soil temperature field around the single U-tube of an underground heat exchanger were studied at the same time. The conclusions had great academic significance to the analysis and designing of the underground heat exchanger.