Buildings.HeatTransfer.Data.BaseClasses

Base classes for package Data

Information

Extends from Modelica.Fluid.Icons.BaseClassLibrary (Icon for library).

Package Content

NameDescription
Buildings.HeatTransfer.Data.BaseClasses.Material Material Thermal properties of materials w/o storage


Buildings.HeatTransfer.Data.BaseClasses.Material Buildings.HeatTransfer.Data.BaseClasses.Material

Thermal properties of materials w/o storage

Information


This is the base record for materials that declares the thermal properties. 

The specific heat capacity can be zero, in which case the material will be modeled as a thermal resistor that does not store energy.

Note that the thermal resistance is in units of m2*K/W and not K/W because this record does not have the surface area as a parameter. The surface area will be defined in the model of the construction that uses this material. This allows use of the same material in walls, floors and ceilings of different surface area.

Extends from Modelica.Icons.Record (Icon for a record).

Parameters

TypeNameDefaultDescription
Lengthx Material thickness [m]
ThermalConductivityk Thermal conductivity [W/(m.K)]
SpecificHeatCapacityc Specific heat capacity [J/(kg.K)]
Densityd Mass density [kg/m3]
RealR Thermal resistance of a unit area of material [m2.K/W]
IntegernStaRef3Number of state variables in a reference material of 0.2 m concrete
BooleansteadyState(c == 0 or d == 0)Flag, if true, then material is computed using steady-state heat conduction
Advanced
IntegernStamax(1, integer(ceil(nStaReal...Actual number of state variables in material
RealpiRef331.4Ratio x/sqrt(alpha) for reference material of 0.2 m concrete
RealpiMatif steadyState then piRef el...Ratio x/sqrt(alpha)
RealnStaRealnStaRef*piMat/piRefNumber of states as a real number

Modelica definition

record Material "Thermal properties of materials w/o storage"
  extends Modelica.Icons.Record;
  parameter Modelica.SIunits.Length x "Material thickness";
  parameter Modelica.SIunits.ThermalConductivity k "Thermal conductivity";
  parameter Modelica.SIunits.SpecificHeatCapacity c "Specific heat capacity";
  parameter Modelica.SIunits.Density d "Mass density";
  parameter Real R(unit="m2.K/W") 
    "Thermal resistance of a unit area of material";
  parameter Integer nStaRef(min=0) = 3 
    "Number of state variables in a reference material of 0.2 m concrete";
  parameter Integer nSta(min=1)=max(1, integer(ceil(nStaReal))) 
    "Actual number of state variables in material";
  parameter Boolean steadyState= (c == 0 or d == 0) 
    "Flag, if true, then material is computed using steady-state heat conduction";
  parameter Real piRef=331.4 
    "Ratio x/sqrt(alpha) for reference material of 0.2 m concrete";
  parameter Real piMat=if steadyState then piRef else x*sqrt(c*d)/sqrt(k) 
    "Ratio x/sqrt(alpha)";
  parameter Real nStaReal(min=0) = nStaRef*piMat/piRef 
    "Number of states as a real number";

end Material;

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