Immediately after the burial was co

Immediately after the burial was completed, the tube was filled with clean water and sealed. After 48 hours, the backfill material in the hole had fully solidified, and the clear water in the tube had fully exchanged heat with the formation. Therefore, the test must be performed 48 hours after the buried tube was sealed. Before the heater is put into operation, start the system water pump to cycle for 2 hours, observe the change curve of the fluid inlet and outlet temperature, and the outlet temperature when the temperature reaches a stable level can be regarded as the temperature of the underground soil without interference. The relationship between inlet and outlet temperature and time is shown in Figure 5.1. As can be seen from Figure 5.1, after a period of operation, the inlet and outlet water temperature of the buried pipe is basically stable, and the outlet temperature fluctuates around 15.10 ° C. Therefore, the initial ground temperature is considered to be 15.10 ° C.