Sizing Calculation Spreadsheet Vertical Geothermal Borefields
Résumé
A simple design procedure for single and multiple borehole configurations for designing vertical geothermal systems based on the borehole sizing equation given in ASHRAE Handbook is presented. Sizing equation proposed by S.P. Kavanaugh and K. Rafferty and recast by M. Bernier is used that is derived by assuming that heat transfer in the ground occurs only by conduction and that moisture evaporation and underground water movement are not significant. For single borehole, it is found that on an annual basis, the net amount of heat rejected into the ground is equivalent to a heat pump operating one-eighth of the time, which corresponds to 1.5 kW. Iterative method is used for multiple boreholes, and it is found that in this case borefield length is 10 150 m with a corresponding borehole depth of 84.6 m and temperature penalty T p is -0.24°C after 10 years of operation