Analysis on thermal behavior of the type of filter tubes of extraction-injection wells in geothermal utilization

Groundwater heat pump (GWHP) has recently gained popularity because of its high efficiency, energy conservation, environment protection, etc. However, thermal breakthrough restricts its sustainable development. In order to delay and minimize thermal breakthrough, a new type of filter tube named as semi-circumference filter tube was proposed and numerical simulations followed. The reliability of the simulation has been validated. The extraction-injection well spacing and the degree of thermal imbalance were selected as the independent variable to study thermo-fluid difference between the semi-circumference filter tube and the traditional one. The pumping temperature evolution, the extent of thermal breakthrough and the energy loss resulting from thermal breakthrough were analyzed. Results show that the semi-circumference filter tube can delay the occurrence time of thermal breakthrough and decrease the energy loss. With a proper extraction-injection well spacing, the pumping temperature of the semi-circumference filter tube can almost keep a constant value, which is in favor of stable and long-term operation of the system.