Tian You

Dynamic Soil Temperature of Ground-Coupled Heat Pump System in Cold Region

Ground-coupled heat pump (GCHP) has been widely used as an energy-saving and environment-friendly heating and cooling system. But for the buildings in cold regions, because the heat extracted from ground is much larger than the heat rejected into it, the ground cannot keep thermal balance and consequently the soil temperature will decrease year by year. With the decrease of the soil temperature, the ground-coupled heat pump system declines in performance or even stops running after a longtime operation. This paper aims at specifically revealing the phenomenon of soil temperature decrease in cold regions by an integrated dynamic simulation. 10 year’s dynamic soil temperatures of GCHP used for just heating and for both heating and cooling in four typical cities are simulated and compared. The results show that the office building using GCHP just for heating has a severer soil temperature decrease: the temperature drop is respectively 11.7 °C in Harbin, 9.6 °C in Shenyang, 9.0 °C in Beijing, 5.8 °C in Zhengzhou. For the system with both heating and cooling, the soil temperature drop is 8.2 °C and 3.4 °C in Harbin and Shenyang, while the soil temperature rise is 0.02 °C and 5.5 °C in Beijing and Zhengzhou. The results of simulation are valuable for the design and operation of GCHP system applied in cold region.