Discussion on geothermal recovery process of deep borehole heat exchanger in layered stratum

To explore the characters of geothermal recovery process of deep borehole heat exchanger, a geothermal recovery process was simulated to explore the difference in stratum temperature distribution change under layered model and uniform model. The results indicated that the geothermal recovery rate is sharp at first and slow down then. The outlet temperature would be higher in the next heat extraction stage if the longer geothermal recovery period was adopted. Considering the time cost during the geothermal recovery period, the suggesting proportion of heat extraction and geothermal recovery could adopt 1:1. In addition, the uniform model cannot reveal the ground temperature variety of layered in geothermal recovery process accurately.