Modelica.Media.IdealGases.Common.Functions

Basic Functions for ideal gases: cp, h, s, thermal conductivity, viscosity

Information

Extends from Modelica.Icons.Package (Icon for standard packages).

Package Content

Name	Description
excludeEnthalpyOfFormation=true	If true, enthalpy of formation Hf is not included in specific enthalpy h
referenceChoice=Modelica.Media.Interfaces.Choices.ReferenceEnthalpy.ZeroAt0K	Choice of reference enthalpy
h_offset=0.0	User defined offset for reference enthalpy, if referenceChoice = UserDefined
methodForThermalConductivity=1
cp_T	Compute specific heat capacity at constant pressure from temperature and gas data
cp_Tlow	Compute specific heat capacity at constant pressure, low T region
cp_Tlow_der	Compute specific heat capacity at constant pressure, low T region
h_T	Compute specific enthalpy from temperature and gas data; reference is decided by the refChoice input, or by the referenceChoice package constant by default
h_T_der	Derivative function for h_T
h_Tlow	Compute specific enthalpy, low T region; reference is decided by the refChoice input, or by the referenceChoice package constant by default
h_Tlow_der	Compute specific enthalpy, low T region; reference is decided by the refChoice input, or by the referenceChoice package constant by default
s0_T	Compute specific entropy from temperature and gas data
s0_Tlow	Compute specific entropy, low T region
s0_Tlow_der	Compute derivative of specific entropy, low T region
dynamicViscosityLowPressure	Dynamic viscosity of low pressure gases
thermalConductivityEstimate	Thermal conductivity of polyatomic gases(Eucken and Modified Eucken correlation)

Modelica.Media.IdealGases.Common.Functions.cp_T

Compute specific heat capacity at constant pressure from temperature and gas data

Information

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

Inputs

Name Description

data Ideal gas data

T Temperature [K]

Name	Description
data	Ideal gas data
T	Temperature [K]

Outputs

Name Description

cp Specific heat capacity at temperature T [J/(kg.K)]

Name	Description
cp	Specific heat capacity at temperature T [J/(kg.K)]

Modelica.Media.IdealGases.Common.Functions.cp_Tlow

Compute specific heat capacity at constant pressure, low T region

Information

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

Inputs

Name Description

data Ideal gas data

T Temperature [K]

Name	Description
data	Ideal gas data
T	Temperature [K]

Outputs

Name Description

cp Specific heat capacity at temperature T [J/(kg.K)]

Name	Description
cp	Specific heat capacity at temperature T [J/(kg.K)]

Modelica.Media.IdealGases.Common.Functions.cp_Tlow_der

Compute specific heat capacity at constant pressure, low T region

Information

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

Inputs

Name Description

data Ideal gas data

T Temperature [K]

dT Temperature derivative

Name	Description
data	Ideal gas data
T	Temperature [K]
dT	Temperature derivative

Outputs

Name Description

cp_der Derivative of specific heat capacity

Name	Description
cp_der	Derivative of specific heat capacity

Modelica.Media.IdealGases.Common.Functions.h_T

Compute specific enthalpy from temperature and gas data; reference is decided by the refChoice input, or by the referenceChoice package constant by default

Information

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

Inputs

Name Description

data Ideal gas data

T Temperature [K]

exclEnthForm If true, enthalpy of formation Hf is not included in specific enthalpy h

refChoice Choice of reference enthalpy

h_off User defined offset for reference enthalpy, if referenceChoice = UserDefined [J/kg]

Name	Description
data	Ideal gas data
T	Temperature [K]
exclEnthForm	If true, enthalpy of formation Hf is not included in specific enthalpy h
refChoice	Choice of reference enthalpy
h_off	User defined offset for reference enthalpy, if referenceChoice = UserDefined [J/kg]

Outputs

Name Description

h Specific enthalpy at temperature T [J/kg]

Name	Description
h	Specific enthalpy at temperature T [J/kg]

Modelica.Media.IdealGases.Common.Functions.h_T_der

Derivative function for h_T

Information

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

Inputs

Name	Description
data	Ideal gas data
T	Temperature [K]
exclEnthForm	If true, enthalpy of formation Hf is not included in specific enthalpy h
refChoice	Choice of reference enthalpy
h_off	User defined offset for reference enthalpy, if referenceChoice = UserDefined [J/kg]
dT	Temperature derivative

Outputs

Name Description

h_der Specific enthalpy at temperature T

Name	Description
h_der	Specific enthalpy at temperature T

Modelica.Media.IdealGases.Common.Functions.h_Tlow

Compute specific enthalpy, low T region; reference is decided by the refChoice input, or by the referenceChoice package constant by default

Information

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

Inputs

Name	Description
data	Ideal gas data
T	Temperature [K]
exclEnthForm	If true, enthalpy of formation Hf is not included in specific enthalpy h
refChoice	Choice of reference enthalpy
h_off	User defined offset for reference enthalpy, if referenceChoice = UserDefined [J/kg]

Outputs

Name Description

h Specific enthalpy at temperature T [J/kg]

Name	Description
h	Specific enthalpy at temperature T [J/kg]

Modelica.Media.IdealGases.Common.Functions.h_Tlow_der

Compute specific enthalpy, low T region; reference is decided by the refChoice input, or by the referenceChoice package constant by default

Information

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

Inputs

Name	Description
data	Ideal gas data
T	Temperature [K]
exclEnthForm	If true, enthalpy of formation Hf is not included in specific enthalpy h
refChoice	Choice of reference enthalpy
h_off	User defined offset for reference enthalpy, if referenceChoice = UserDefined [J/kg]
dT	Temperature derivative [K/s]

Outputs

Name Description

h_der Derivative of specific enthalpy at temperature T [J/(kg.s)]

Name	Description
h_der	Derivative of specific enthalpy at temperature T [J/(kg.s)]

Modelica.Media.IdealGases.Common.Functions.s0_T

Compute specific entropy from temperature and gas data

Information

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

Inputs

Name Description

data Ideal gas data

T Temperature [K]

Name	Description
data	Ideal gas data
T	Temperature [K]

Outputs

Name Description

s Specific entropy at temperature T [J/(kg.K)]

Name	Description
s	Specific entropy at temperature T [J/(kg.K)]

Modelica.Media.IdealGases.Common.Functions.s0_Tlow

Compute specific entropy, low T region

Information

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

Inputs

Name Description

data Ideal gas data

T Temperature [K]

Name	Description
data	Ideal gas data
T	Temperature [K]

Outputs

Name Description

s Specific entropy at temperature T [J/(kg.K)]

Name	Description
s	Specific entropy at temperature T [J/(kg.K)]

Modelica.Media.IdealGases.Common.Functions.s0_Tlow_der

Compute derivative of specific entropy, low T region

Information

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

Inputs

Name Description

data Ideal gas data

T Temperature [K]

T_der Temperature derivative

Name	Description
data	Ideal gas data
T	Temperature [K]
T_der	Temperature derivative

Outputs

Name Description

s Specific entropy at temperature T [J/(kg.K)]

Name	Description
s	Specific entropy at temperature T [J/(kg.K)]

Modelica.Media.IdealGases.Common.Functions.dynamicViscosityLowPressure

Dynamic viscosity of low pressure gases

Information

The used formula are based on the method of Chung et al (1984, 1988) referred to in ref [1] chapter 9. The formula 9-4.10 is the one being used. The Formula is given in non-SI units, the following conversion constants were used to transform the formula to SI units:

Const1_SI: The factor 10^(-9.5) =10^(-2.5)*1e-7 where the factor 10^(-2.5) originates from the conversion of g/mol->kg/mol + cm^3/mol->m^3/mol and the factor 1e-7 is due to conversion from microPoise->Pa.s.
Const2_SI: The factor 1/3.335641e-27 = 1e-3/3.335641e-30 where the factor 3.335641e-30 comes from debye->C.m and 1e-3 is due to conversion from cm^3/mol->m^3/mol

References:

[1] Bruce E. Poling, John E. Prausnitz, John P. O'Connell, "The Properties of Gases and Liquids" 5th Ed. Mc Graw Hill.

Author

T. Skoglund, Lund, Sweden, 2004-08-31

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

Inputs

Name Description

T Gas temperature [K]

Tc Critical temperature of gas [K]

M Molar mass of gas [kg/mol]

Vc Critical molar volume of gas [m3/mol]

w Acentric factor of gas

mu Dipole moment of gas molecule [debye]

k Special correction for highly polar substances

Name	Description
T	Gas temperature [K]
Tc	Critical temperature of gas [K]
M	Molar mass of gas [kg/mol]
Vc	Critical molar volume of gas [m3/mol]
w	Acentric factor of gas
mu	Dipole moment of gas molecule [debye]
k	Special correction for highly polar substances

Outputs

Name Description

eta Dynamic viscosity of gas [Pa.s]

Name	Description
eta	Dynamic viscosity of gas [Pa.s]

Modelica.Media.IdealGases.Common.Functions.thermalConductivityEstimate

Thermal conductivity of polyatomic gases(Eucken and Modified Eucken correlation)

Information

This function provides two similar methods for estimating the thermal conductivity of polyatomic gases. The Eucken method (input method == 1) gives good results for low temperatures, but it tends to give an underestimated value of the thermal conductivity (lambda) at higher temperatures.
The Modified Eucken method (input method == 2) gives good results for high-temperatures, but it tends to give an overestimated value of the thermal conductivity (lambda) at low temperatures.

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

Inputs

Name Description

Cp Constant pressure heat capacity [J/(kg.K)]

eta Dynamic viscosity [Pa.s]

method 1: Eucken Method, 2: Modified Eucken Method

data Ideal gas data

Name	Description
Cp	Constant pressure heat capacity [J/(kg.K)]
eta	Dynamic viscosity [Pa.s]
method	1: Eucken Method, 2: Modified Eucken Method
data	Ideal gas data

Outputs

Name Description

lambda Thermal conductivity [W/(m.k)] [W/(m.K)]

Name	Description
lambda	Thermal conductivity [W/(m.k)] [W/(m.K)]

Automatically generated Mon Sep 23 17:21:02 2013.