.Buildings.Fluid.Geothermal.Boreholes.BaseClasses.HexInternalElement

Information

Model for the heat transfer between the fluid and within the borehole filling. This model computes the dynamic response of the fluid in the tubes, the heat transfer between the fluid and the borehole filling, and the heat storage within the fluid and the borehole filling.

This model computes the different thermal resistances present in a single-U-tube borehole using the method of Bauer et al. (2011) and computing explicitly the fluid-to-ground thermal resistance R_b and the grout-to-grout resistance R_a as defined by Hellstroem (1991) using the multipole method. The multipole method is implemented in Buildings.Fluid.Geothermal.Boreholes.BaseClasses.singleUTubeResistances. The convection resistance is calculated using the Dittus-Boelter correlation as implemented in Buildings.Fluid.Geothermal.Boreholes.BaseClasses.convectionResistance.

The figure below shows the thermal network set up by Bauer et al. (2010).

References

G. Hellström. Ground heat storage: thermal analyses of duct storage systems (Theory). Dept. of Mathematical Physics, University of Lund, Sweden, 1991.

D. Bauer, W. Heidemann, H. Müller-Steinhagen, and H.-J. G. Diersch. Thermal resistance and capacity models for borehole heat exchangers . International Journal Of Energy Research, 35:312–320, 2011.

Contents

Revisions

• May 6, 2015, by Michael Wetter:
  Removed assignement of vol.allowFlowReversal as this is done in the base class.
• June 18, 2014, by Michael Wetter:
  Added initialization for temperatures and derivatives of capFil1 and capFil2 to avoid a warning during translation.
• February 14, 2014, by Michael Wetter:
  Removed unused parameters B0 and B1.
• January 24, 2014, by Michael Wetter:
  Revised implementation, added comments, replaced HeatTransfer.Windows.BaseClasses.ThermalConductor with resistance models from the Modelica Standard Library.
• January 23, 2014, by Damien Picard:
  First implementation.