(a) Experimental data and simulation results [17
]. (b) Variation of rock temperature with radial distance at the end of first and tenth heating seasons with a depth of 2500 m. (c) Variation of the annual mean extracted thermal output with time. The symbol Q represents the extracted thermal output from DBHE, Tin
is the injection water temperature, Tout
is the extracted water temperature, and r is the radial distance from the well tube.