.Buildings.Fluid.HeatExchangers.RadiantSlabs.BaseClasses.Functions.AverageResistance

Information

This function computes a fictitious thermal resistance between the pipe outer wall and a fictitious, average temperature of the plane that contains the pipes. The equation is the same as is implemented in TRNSYS 17 Type 56 active layer component, manual page 197-201. Different equations are used for

• floor heating systems (if sysTyp == Buildings.Fluid.HeatExchangers.RadiantSlabs.Types.SystemType.Floor),
• radiant heating or cooling systems in ceilings and walls (if sysTyp == Buildings.Fluid.HeatExchangers.RadiantSlabs.Types.SystemType.Ceiling_Wall_or_Capillary and disPip/dPipOut ≥ 5.8), and
• capillary tube systems (if sysTyp == Buildings.Fluid.HeatExchangers.RadiantSlabs.Types.SystemType.Ceiling_Wall_or_Capillary and disPip/dPipOut < 5.8).

Limitations

The resistance Rx is based on a steady-state heat transfer analysis. Therefore, it is only valid during steady-state. For a fully dynamic model, a finite element method for the radiant slab would need to be implemented.

Interface

function AverageResistance
  extends Modelica.Icons.Function;
  input Modelica.Units.SI.Distance disPip "pipe distance";
  input Modelica.Units.SI.Diameter dPipOut "pipe outside diameter";
  input Modelica.Units.SI.ThermalConductivity k "pipe level construction element thermal conductivity";
  input Buildings.Fluid.HeatExchangers.RadiantSlabs.Types.SystemType sysTyp "Type of radiant system";
  input Modelica.Units.SI.ThermalConductivity kIns "floor slab insulation thermal conductivity";
  input Modelica.Units.SI.Thickness dIns "floor slab insulation thickness";
  output Modelica.Units.SI.ThermalInsulance Rx "Thermal insulance";
end AverageResistance;

Revisions

• June 16, 2020, by Ettore Zanetti and Michael Wetter:
  Corrected inequality test on alpha, and changed print statement to an assertion with assertion level set to warning.
  This is for issue 2009.
• April 17, 2012, by Michael Wetter:
  Added term 1/s in computation of infSum.
• April 5, 2012, by Michael Wetter:
  Revised implementation.
• April 3, 2012, by Xiufeng Pang:
  First implementation.