Thermal performance of a standing column well geothermal heat exchanger system using re-injection of bleeding water

Abstract

A study on the change in thermal conductivity according to the bleeding rate of a standing column well (SCW)-type geothermal heat exchanger is experimentally performed in which the thermal conductivity of the geothermal heat exchanger is improved by approximately 165.4% at a bleeding rate of 10%. In studies conducted overseas, a numerical analysis was conducted, in which the effective thermal conductivity was improved by approximately 186.8% at a maximum bleeding rate of 30%. In this study, the change in the thermal conductivity was investigated when the bleeding water of a submerged heat-exchanger was re-injected into other adjacent SCW-type subsea heat exchangers using an artificial recharging method. The thermal conductivity in the two-well type SCW geothermal heat exchanger was 4.0 times higher than that of a single-well type SCW geothermal heat exchanger measured at the same bleeding rate. We consider that the two wells in the SCW geothermal heat exchangers are connected to each other by 90 and 280 m underground. Additionally, we consider that the bled discharge water in each geothermal heat exchanger is returned to the other underground heat-exchanger.