This model computes the different thermal resistances present in a double 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.
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.
function internalResistancesTwoUTube extends IBPSA.Fluid.Geothermal.Borefields.BaseClasses.Boreholes.BaseClasses.Functions.partialInternalResistances; output Modelica.SIunits.ThermalResistance Rgb "Thermal resistance between a grout capacity and the borehole wall, as defined by Bauer et al (2010)"; output Modelica.SIunits.ThermalResistance Rgg1 "Thermal resistance between two neightbouring grout capacities, as defined by Bauer et al (2010)"; output Modelica.SIunits.ThermalResistance Rgg2 "Thermal resistance between two grout capacities opposite to each other, as defined by Bauer et al (2010)"; output Modelica.SIunits.ThermalResistance RCondGro "Thermal resistance between a pipe wall and the grout capacity, as defined by Bauer et al (2010)"; end internalResistancesTwoUTube;