WOLFRAM SYSTEM MODELER

TableBased

Incompressible medium properties based on tables

Package Contents

	invertTemp Function to invert temperatures
	BaseProperties Base properties of T dependent medium
	setState_pTX Returns state record, given pressure and temperature
	setState_dTX Returns state record, given pressure and temperature
	setState_pT Returns state record as function of p and T
	setState_phX Returns state record, given pressure and specific enthalpy
	setState_ph Returns state record as function of p and h
	setState_psX Returns state record, given pressure and specific entropy
	setState_ps Returns state record as function of p and s
	setSmoothState Return thermodynamic state so that it smoothly approximates: if x > 0 then state_a else state_b
	specificHeatCapacityCv Specific heat capacity at constant volume (or pressure) of medium
	specificHeatCapacityCp Specific heat capacity at constant volume (or pressure) of medium
	dynamicViscosity Return dynamic viscosity as a function of the thermodynamic state record
	thermalConductivity Return thermal conductivity as a function of the thermodynamic state record
	s_T Compute specific entropy
	specificEntropy Return specific entropy as a function of the thermodynamic state record
	h_T Compute specific enthalpy from temperature
	h_T_der Compute specific enthalpy from temperature
	h_pT Compute specific enthalpy from pressure and temperature
	density_T Return density as function of temperature
	temperature Return temperature as a function of the thermodynamic state record
	pressure Return pressure as a function of the thermodynamic state record
	density Return density as a function of the thermodynamic state record
	specificEnthalpy Return specific enthalpy as a function of the thermodynamic state record
	specificInternalEnergy Return specific internal energy as a function of the thermodynamic state record
	T_ph Compute temperature from pressure and specific enthalpy
	T_ps Compute temperature from pressure and specific enthalpy
	specificEnthalpyOfT Protected Return specific enthalpy from pressure and temperature, taking the flag enthalpyOfT into account

Package Constants (51)

ThermoStates	Value: if enthalpyOfT then Modelica.Media.Interfaces.Choices.IndependentVariables.T else Modelica.Media.Interfaces.Choices.IndependentVariables.pT Type: IndependentVariables Description: Enumeration type for independent variables
mediumName	Value: "tableMedium" Type: String Description: Name of the medium
substanceNames	Value: {mediumName} Type: String[:] Description: Names of the mixture substances. Set substanceNames={mediumName} if only one substance.
extraPropertiesNames	Value: fill("", 0) Type: String[:] Description: Names of the additional (extra) transported properties. Set extraPropertiesNames=fill("",0) if unused
singleState	Value: true Type: Boolean Description: = true, if u and d are not a function of pressure
reducedX	Value: true Type: Boolean Description: = true if medium contains the equation sum(X) = 1.0; set reducedX=true if only one substance (see docu for details)
fixedX	Value: true Type: Boolean Description: = true if medium contains the equation X = reference_X
reference_p	Value: 1.013e5 Type: AbsolutePressure (Pa) Description: Reference pressure of Medium: default 1 atmosphere
reference_T	Value: 298.15 Type: Temperature (K) Description: Reference temperature of Medium: default 25 deg Celsius
reference_X	Value: fill(1 / nX, nX) Type: MassFraction[nX] (kg/kg) Description: Default mass fractions of medium
p_default	Value: 101325 Type: AbsolutePressure (Pa) Description: Default value for pressure of medium (for initialization)
T_default	Value: Modelica.Units.Conversions.from_degC(20) Type: Temperature (K) Description: Default value for temperature of medium (for initialization)
h_default	Value: specificEnthalpy_pTX(p_default, T_default, X_default) Type: SpecificEnthalpy (J/kg) Description: Default value for specific enthalpy of medium (for initialization)
X_default	Value: reference_X Type: MassFraction[nX] (kg/kg) Description: Default value for mass fractions of medium (for initialization)
C_default	Value: fill(0, nC) Type: ExtraProperty[nC] Description: Default value for trace substances of medium (for initialization)
nS	Value: size(substanceNames, 1) Type: Integer Description: Number of substances
nX	Value: nS Type: Integer Description: Number of mass fractions
nXi	Value: if fixedX then 0 else if reducedX then nS - 1 else nS Type: Integer Description: Number of structurally independent mass fractions (see docu for details)
nC	Value: size(extraPropertiesNames, 1) Type: Integer Description: Number of extra (outside of standard mass-balance) transported properties
C_nominal	Value: 1.0e-6 * ones(nC) Type: Real[nC] Description: Default for the nominal values for the extra properties
enthalpyOfT	Value: true Type: Boolean Description: True if enthalpy is approximated as a function of T only, (p-dependence neglected)
densityOfT	Value: size(tableDensity, 1) > 1 Type: Boolean Description: True if density is a function of temperature
T_min	Value: Type: Temperature (K) Description: Minimum temperature valid for medium model
T_max	Value: Type: Temperature (K) Description: Maximum temperature valid for medium model
T0	Value: 273.15 Type: Temperature (K) Description: Reference Temperature
h0	Value: 0 Type: SpecificEnthalpy (J/kg) Description: Reference enthalpy at T0, reference_p
s0	Value: 0 Type: SpecificEntropy (J/(kg⋅K)) Description: Reference entropy at T0, reference_p
MM_const	Value: 0.1 Type: MolarMass (kg/mol) Description: Molar mass
npol	Value: 2 Type: Integer Description: Degree of polynomial used for fitting
npolDensity	Value: npol Type: Integer Description: Degree of polynomial used for fitting rho(T)
npolHeatCapacity	Value: npol Type: Integer Description: Degree of polynomial used for fitting Cp(T)
npolViscosity	Value: npol Type: Integer Description: Degree of polynomial used for fitting eta(T)
npolVaporPressure	Value: npol Type: Integer Description: Degree of polynomial used for fitting pVap(T)
npolConductivity	Value: npol Type: Integer Description: Degree of polynomial used for fitting lambda(T)
neta	Value: size(tableViscosity, 1) Type: Integer Description: Number of data points for viscosity
tableDensity	Value: Type: Real[:,2] Description: Table for rho(T)
tableHeatCapacity	Value: Type: Real[:,2] Description: Table for Cp(T)
tableViscosity	Value: Type: Real[:,2] Description: Table for eta(T)
tableVaporPressure	Value: Type: Real[:,2] Description: Table for pVap(T)
tableConductivity	Value: Type: Real[:,2] Description: Table for lambda(T)
TinK	Value: Type: Boolean Description: True if T[K],Kelvin used for table temperatures
hasDensity	Value: not size(tableDensity, 1) == 0 Type: Boolean Description: True if table tableDensity is present
hasHeatCapacity	Value: not size(tableHeatCapacity, 1) == 0 Type: Boolean Description: True if table tableHeatCapacity is present
hasViscosity	Value: not size(tableViscosity, 1) == 0 Type: Boolean Description: True if table tableViscosity is present
hasVaporPressure	Value: not size(tableVaporPressure, 1) == 0 Type: Boolean Description: True if table tableVaporPressure is present
invTK	Value: if size(tableViscosity, 1) > 0 then if TinK then 1 ./ tableViscosity[:, 1] else 1 ./ Cv.from_degC(tableViscosity[:, 1]) else fill(0, neta) Type: Real[neta]
poly_rho	Value: if hasDensity then Polynomials.fitting(tableDensity[:, 1], tableDensity[:, 2], npolDensity) else zeros(npolDensity + 1) Type: Real[:]
poly_Cp	Value: if hasHeatCapacity then Polynomials.fitting(tableHeatCapacity[:, 1], tableHeatCapacity[:, 2], npolHeatCapacity) else zeros(npolHeatCapacity + 1) Type: Real[:]
poly_eta	Value: if hasViscosity then Polynomials.fitting(invTK, Math.log(tableViscosity[:, 2]), npolViscosity) else zeros(npolViscosity + 1) Type: Real[:]
poly_pVap	Value: if hasVaporPressure then Polynomials.fitting(tableVaporPressure[:, 1], tableVaporPressure[:, 2], npolVaporPressure) else zeros(npolVaporPressure + 1) Type: Real[:]
poly_lam	Value: if size(tableConductivity, 1) > 0 then Polynomials.fitting(tableConductivity[:, 1], tableConductivity[:, 2], npolConductivity) else zeros(npolConductivity + 1) Type: Real[:]

Information

This information is part of the Modelica Standard Library maintained by the Modelica Association.

This is the base package for medium models of incompressible fluids based on tables. The minimal data to provide for a useful medium description is tables of density and heat capacity as functions of temperature.

It should be noted that incompressible media only have 1 state per control volume (usually T), but have both T and p as inputs for fully correct properties. The error of using only T-dependent properties is small, therefore a Boolean flag enthalpyOfT exists. If it is true, the enumeration Choices.IndependentVariables is set to Choices.IndependentVariables.T otherwise it is set to Choices.IndependentVariables.pT.

Using the package TableBased

To implement a new medium model, create a package that extends TableBased and provides one or more of the constant tables:

tableDensity        = [T, d];
tableHeatCapacity   = [T, Cp];
tableConductivity   = [T, lam];
tableViscosity      = [T, eta];
tableVaporPressure  = [T, pVap];

The table data is used to fit constant polynomials of order npol, the temperature data points do not need to be same for different properties. Properties like enthalpy, inner energy and entropy are calculated consistently from integrals and derivatives of d(T) and Cp(T). The minimal data for a useful medium model is thus density and heat capacity. Transport properties and vapor pressure are optional, if the data tables are empty the corresponding function calls can not be used.

Wolfram Language

In[1]:=

SystemModel["Modelica.Media.Incompressible.TableBased"]

Out[1]:=

Extended by (2)

Essotherm650

Modelica.Media.Incompressible.Examples

Essotherm thermal oil

Glycol47

Modelica.Media.Incompressible.Examples

1,2-Propylene glycol, 47% mixture with water

Enable JavaScript to interact with content and submit forms on Wolfram websites. Learn how »