Immediately after the installation

Immediately after the installation of the buried pipe, the pipe is filled with clean water and sealed. After 48 hours, the backfill material in the hole has fully solidified, and the clean water in the pipe has fully exchanged heat with the formation. Therefore, the test must be performed 48 hours after the buried pipe is sealed. Before the heater is put into operation, the system starts the system water pump for 2 hours and observes the change curve of the fluid inlet and outlet temperature. The outlet temperature when the temperature reaches a stable temperature 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 5.5. As can be seen from Figure 5.5, after a period of operation, the inlet and outlet water temperature of the buried pipe is basically stable, and the outlet temperature fluctuates around 15.55 ° C. Therefore, the initial ground temperature is considered to be 15.55 ° C.