Temperaturzoner för lagring av värmeenergi i cirkulärt borrhålsfält
G-functionBore holeThermal energy storageEEDEarth Energy DesignerFLSFinite Line SourceCOMSOLBorehole thermal energy storageGround source heat pumpsBorehole heat exchangerG-funktionGeoeneriBorrhålBergvärmeSEECCOMSOLEEDFLSBorrhålslagerEarth Energy DesignerBerggrund
The thermal response of a borehole field is often described by non?dimensional response factors called gfunctions.The g?function was firstly generated as a numerical solution based on SBM (Superposition BoreholeModel). An analytical approach, the FLS (Finite Line Source), is also accepted for generating the g?function. In thiswork the potential to numerically produce g?functions is studied for circular borehole fields using the commercialsoftware COMSOL. The numerical method is flexible and allows the generation of g?functions for any boreholefield geometry. The approach is partially validated by comparing the solution for a square borehole field containing36 boreholes (6x6) with g?functions generated with the FLS approach and with the program EED (Earth EnergyDesigner). The latter is based on Eskilsons SBM, one of the first documents where the concept of g?functions wasintroduced. Once the approach is validated, the square COMSOL model is compared with a circular geometryborehole field developed by the same method, consisting of 3 concentric rings having 6, 12, and 18 boreholes.Finally the influence on the circular geometry g?function is studied when connecting the boreholes in radial zoneswith different thermal loads.