Abstract:In order to solve the problem of negative heat transfer effect caused by excessive buried depth of vertical ground heat exchanger, a numerical model of single U-type ground heat exchanger with axial rock-soil body stratification was established according to the geological conditions in loess Plateau area. Through numerical simulation, the influence of changing the aquifer thickness, the seepage velocity, and the height of the water table on the heat transfer performance of the ground heat exchanger is analyzed, and a method to determine the optimal buried depth of the exchanger based on the typical aquifer thickness is proposed. The results show that when the actual aquifer thickness does not exceed the typical aquifer thickness, the optimal buried depth of ground heat exchanger is the bottom of the actual aquifer. On the contrary, the optimal buried depth is the bottom of typical aquifer. With the decrease of seepage velocity, the thickness of typical aquifer first increases and then tends to remain unchanged, reaching a maximum of 30 m when the seepage velocity is 1×10-6m/s. The increase of the groundwater table has no effect on the thickness of the typical aquifer, but it increases the location of the typical aquifer, making the optimal buried depth smaller.#$NL