Simulation study on the effect of thermal barrier well on the heat transfer of groundwater heat pump

GWHP system is easy to cause the thermal breakthrough which will reduce the operation efficiency, when the site area is small. In the design of GWHP, by setting up a thermal barrier well between the pumping and recharging well can reduce the heat transfer speed between pumping and recharging well, which is conducive to prolonging the occurrence time of thermal breakthrough. 36 groups of GWHP operation scenarios under the cooling condition are simulated through heat transfer model, and the influence of the location, structure and recharge quantity of the thermal barrier well on the thermal breakthrough and the aquifer’s temperature field are analyzed. The results show that the increase of recharge quantity of the thermal barrier well is conducive to improving the thermal barrier effect, but the degree of improvement decreases with the increase of recharge quantity. At the same time, with the increase of recharge quantity, the maximum drawdown will increase linearly. The location of the thermal barrier well has little influence on the aquifer temperature field and the closer the barrier well is to the recharging well, the later the thermal breakthrough time will be. Increasing the length of the filter tube in the heat barrier well can improve the thermal barrier effect, and the effect of the thermal barrier is gradually enhanced with the increase of the recharge quantity. In addition, through the long-time simulation of model, it is found that the operation of the heat barrier well can concentrate the energy near the recharging well. When the GWHP adopts the exchange operation mode of pumping and recharging well, it can make full use of the aquifer energy storage and improve the operation efficiency of heat pump.