Welcome to the seventh part of the course ‘Design borefields with confidence’.
Summary of part 6
In the last part of the course, we stepped away from the traditional, smooth geothermal probes and looked at some innovative solutions and the advantages they bring to the design table.
In Part 6.1, the TurboCollector from MuoviTech was introduced. This is a regular circular probe with internal fins that enhance turbulence. Due to these fins, the transition from laminar to turbulent flow now occurs at Re = 1700 instead of around Re = 2300.
In Part 6.2, the younger cousin of the TurboCollector, the MuoviELLIPSE was discussed. As the name suggests, this is now not a circular probe but an elliptical one with the same internal fins to enhance the turbulence. Due to its elliptical design, the MuoviELLIPSE can be used in smaller boreholes.
In Part 6.3, the GEROtherm VARIO and FLUX probes from HakaGerodur were discussed. These are circular probes with a varying wall thickness in order to minimise pressure losses whilst maintaining the same pressure rating as a regular probe.
Content of part 7
Up until now, the course has been rather general, talking about thermal and hydraulic models as well as sensitivities in design. In this part, the focus will be on the actual design of shallow geothermal projects with the help of the methods provided to you in GHEtool Cloud.
In the first chapter, we’ll revisit the temperature profiles once again, talking about the difference between inlet, outlet and average fluid temperatures in borefield design. Understanding this difference is key when talking about the required borefield size.
In the second chapter, the different methodologies to calculate the required borehole depth will be discussed, together with an explanation of the very common gradient error.
In chapter 3, the methodology to calculate both the required depth and the optimal borefield configuration will be discussed, together with the importance of using an artificial neural network.
In the last chapter of this part, the importance of thermal response tests will be discussed, together with how you can analyse them in GHEtool. Although somewhat different from the other topics in this chapter, knowing the ground properties is really important when determining the actual required borefield size.