functionAverageResistance

Average fictitious resistance for plane that contains the pipes

Extends from Modelica.Icons.Function (Icon for functions).

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.

Inputs

Type	Name	Description
Modelica.Units.SI.Distance	disPip	pipe distance
Modelica.Units.SI.Diameter	dPipOut	pipe outside diameter
Modelica.Units.SI.ThermalConductivity	k	pipe level construction element thermal conductivity
Buildings.Fluid.HeatExchangers.RadiantSlabs.Types.SystemType	sysTyp	Type of radiant system
Modelica.Units.SI.ThermalConductivity	kIns	floor slab insulation thermal conductivity
Modelica.Units.SI.Thickness	dIns	floor slab insulation thickness

Outputs

Type	Name	Default	Description
Modelica.Units.SI.ThermalInsulance	Rx		Thermal insulance

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.