| Title | Studies on the Borehole Heat Exchanger Performance Enhanced by Ground Water Flow in a GSHP |
|---|---|
| Authors | Byoung Ohan SHIM, Seong-Kyun KIM |
| Year | 2020 |
| Conference | World Geothermal Congress |
| Keywords | borehole heat exchanger, GSHP, closed loop, open loop, ground water flow, heat transfer rate |
| Abstract | Many types of borehole heat exchanger (BHE) have been developed in several countries according to the status of geological and hydrological conditions. The heat transfer rate (HTR) of BHE is depends on the thermophysical parameters. The range of HTR can be highly different in closed and open loop type having pros and cons based on hydrogeological status. It is generally known that the ground water flow over certain velocity would increase the HTR of closed loop BHE and the effect of ground water movement is critical for the performance. We installed a pilot GSHP system with open loop and closed loop type BHE for three stories building having one BHE well in 200 mm diameter installed with closed loop and open loop together, one injection well and one observation. The hydraulic tests were conducted in the wells and the effective thermal conductivity was measured by thermal response test in the BHE. HTR tests by four different conditions associated with the control of ground water pumping and GSHP operation were continued during about a month in heating season. From these tests we estimated the sustainability of the GSHP performance and ground temperature. The average circulation fluid temperature was converged at around 10 degree Celsius during the test condition with ground water pumping during a specified heating load. This study would provide the improved design information of GSHP with a ground water flow and various BHE types. |