functioninternalResistancesOneUTube

Thermal resistances for single U-tube, according to Bauer et al. (2011)

Extends from AixLib.Fluid.Geothermal.Borefields.BaseClasses.Boreholes.BaseClasses.Functions.partialInternalResistances (Partial model for borehole resistance calculation).

Information

This model computes the different thermal resistances present in a single-U-tube borehole using the method of Bauer et al. (2011). It also computes the fluid-to-ground thermal resistance Rb and the grout-to-grout thermal resistance Ra as defined by Claesson and Hellstrom (2011) using the multipole method.

References

J. Claesson and G. Hellstrom. Multipole method to calculate borehole thermal resistances in a borehole heat exchanger. HVAC&R Research, 17(6): 895-911, 2011.

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.

Inputs

TypeNameDefaultDescription
Booleanuse_Rb (from partialInternalResistances)falseTrue if the value Rb should be used instead of calculated
RealRb (from partialInternalResistances)Borehole thermal resistance
Modelica.Units.SI.HeighthSeg (from partialInternalResistances)Height of the element
Modelica.Units.SI.RadiusrBor (from partialInternalResistances)Radius of the borehole
Modelica.Units.SI.RadiusrTub (from partialInternalResistances)Radius of the tube
Modelica.Units.SI.LengtheTub (from partialInternalResistances)Thickness of the tubes
Modelica.Units.SI.Lengthsha (from partialInternalResistances)Shank spacing, defined as the distance between the center of a pipe and the center of the borehole
Modelica.Units.SI.ThermalConductivitykFil (from partialInternalResistances)Thermal conductivity of the grout
Modelica.Units.SI.ThermalConductivitykSoi (from partialInternalResistances)Thermal conductivity of the soi
Modelica.Units.SI.ThermalConductivitykTub (from partialInternalResistances)Thermal conductivity of the tube
Modelica.Units.SI.ThermalConductivitykMed (from partialInternalResistances)Thermal conductivity of the fluid
Modelica.Units.SI.DynamicViscositymuMed (from partialInternalResistances)Dynamic viscosity of the fluid
Modelica.Units.SI.SpecificHeatCapacitycpMed (from partialInternalResistances)Specific heat capacity of the fluid
Modelica.Units.SI.MassFlowRatem_flow_nominal (from partialInternalResistances)Nominal mass flow rate
StringinstanceName (from partialInternalResistances)"undeclared caller"Instance name of the model or block that calls this function

Outputs

TypeNameDefaultDescription
Realx (from partialInternalResistances)Capacity location
Modelica.Units.SI.ThermalResistanceRgbThermal resistance between grout zone and borehole wall
Modelica.Units.SI.ThermalResistanceRggThermal resistance between the two grout zones
Modelica.Units.SI.ThermalResistanceRCondGroThermal resistance between: pipe wall to capacity in grout

Revisions

  • July 9, 2025, by Jianjun Hu:
    Added missing value assignment.
    This is for IBPSA, #2030.
  • November 22, 2023, by Michael Wetter:
    Corrected use of getInstanceName() which was called inside a function which is not allowed.
    This is for IBPSA, #1814.
  • February 7, 2022, by Michael Wetter:
    Changed function to be pure.
    This is for IBPSA, #1582.
  • December 11, 2021, by Michael Wetter:
    Added impure declaration for MSL 4.0.0.
  • July 18, 2018 by Massimo Cimmino:
    Implemented multipole method.
  • February 14, 2014 by Michael Wetter:
    Added an assert statement to test for non-physical values.
  • February 12, 2014, by Damien Picard:
    Remove the flow dependency of the resistances, as this function calculates the conduction resistances only.
  • January 24, 2014, by Michael Wetter:
    Revised implementation.
  • January 23, 2014, by Damien Picard:
    First implementation.