Abstract：

Taking the double-U type ground heat exchanger (GHE) as example, performs in-situ thermal response tests in three different seasons, and the results show that there does exist the seasonal effect. For the same heating power, the thermal performance of GHE in winter is better than that in summer, where the difference is mainly caused by the seasonal variation of the initial temperature and thermal conductivity of the ground. Besides, the disturbance of the boring process on the initial ground temperature is different with the seasonal variation. Suggests that the above seasonal effect should be taken into full consideration during the design of large-scale ground-source heat pump systems.