Chao-Seader¶

Chao-Seader correlation for hydrocarbon mixtures with hydrogen and light gases: liquid fugacity from a pure-component correlation and a regular-solution activity coefficient, vapor from the Redlich-Kwong equation of state, enthalpy from Lee-Kesler.

DWSIM.Thermodynamics.PropertyPackages.ChaoSeaderPropertyPackage
Assembly DWSIM.Thermodynamics.dll · Object ← PropertyPackage ← ChaoSeaderPropertyPackage
Name in the flowsheet Chao-Seader · FluentAPI PropertyPackages.ChaoSeader

Scope¶

Chao-Seader (CS) is a semi-empirical correlation for hydrocarbon mixtures with hydrogen and light gases: refinery and gas-plant streams, hydrotreater and reformer separators, crude and naphtha fractionation. The guide gives its range as heavy hydrocarbon systems below 10 342 kPa (1500 psia) and between -18 and 260 °C. The DWSIM property package selection guide lists it, with Grayson-Streed and Lee-Kesler-Plöcker, for systems with a high hydrogen content.

The K-value of each compound is φ_i^L / φ_i^V. The liquid fugacity coefficient is the product of two terms:

a pure-component term ν_i, log ν_i = log ν_i⁽⁰⁾ + ω_i log ν_i⁽¹⁾, where log ν⁽⁰⁾ is a polynomial in the reduced temperature with pressure terms (with coefficient sets of its own for hydrogen and methane) and ω_i is the Chao-Seader acentric factor;
a regular-solution activity coefficient, ln γ_i = V_i (δ_i - δ̄)² / RT, with the liquid molar volume V_i, the solubility parameter δ_i, and δ̄ their volume-fraction average over the liquid.

The vapor fugacity coefficient comes from the Redlich-Kwong equation of state. These correlations give only the phase equilibrium: enthalpy, entropy and heat capacities of both phases are Lee-Kesler departure functions, the vapor density comes from the Lee-Kesler compressibility factor, and the liquid density from the experimental data or the Rackett and COSTALD correlations.

The package has no binary interaction parameters. Each compound carries three Chao-Seader parameters: the modified acentric factor, the solubility parameter and the liquid molar volume (the compound creator and the petroleum characterization tools fill them). Without a modified acentric factor the ordinary acentric factor is used; a compound without a solubility parameter is treated as an ideal liquid component (activity coefficient 1) and is left out of the volume-fraction averages.

DWSIM supplies analytical temperature derivatives of the fugacity coefficients of this package for the flash and the column solvers; the composition derivative falls back to finite differences.

Limitations¶

The correlation was built for hydrocarbons with hydrogen and light gases; water and polar compounds need another package.
Keep to its range (below 10 342 kPa, -18 to 260 °C). For heavy hydrocarbon systems with a high hydrogen content the guide recommends Grayson-Streed.

Example¶

This code runs on every build of this site, and the output below is what it printed.

Python

feed = {"Hydrogen": 60.0, "Methane": 8.0, "Ethane": 4.0, "Propane": 3.0,      # mol/s
        "N-butane": 3.0, "N-pentane": 4.0, "N-hexane": 8.0, "N-heptane": 10.0}
fs = (Flowsheet.Create("ChaoSeaderExample")
      .WithCompounds(*feed)
      .WithPropertyPackage(PropertyPackages.ChaoSeader))

effluent = fs.AddMaterialStream("Separator feed").At(Q.Celsius(40.0), Q.Bar(25.0))
for name, flow in feed.items():
    effluent.SetCompoundMolarFlow(name, flow)

fs.Solve()

s = effluent.Object
vapor, liquid = s.Phases[2], s.Phases[3]
K = lambda c: vapor.Compounds[c].MoleFraction / liquid.Compounds[c].MoleFraction
print(f"Vapor fraction           = {vapor.Properties.molarfraction:.4f}")
print(f"Hydrogen in the vapor    = {vapor.Compounds['Hydrogen'].MoleFraction:.4f} (mole fraction)")
print(f"Hydrogen in the liquid   = {liquid.Compounds['Hydrogen'].MoleFraction:.4f} (mole fraction)")
print(f"K-values H2 / CH4 / C7   = {K('Hydrogen'):.2f} / {K('Methane'):.2f} / {K('N-heptane'):.4f}")
print(f"Liquid / vapor density   = {liquid.Properties.density:.1f} / {vapor.Properties.density:.2f} kg/m3")

Output

Vapor fraction           = 0.7480
Hydrogen in the vapor    = 0.7966 (mole fraction)
Hydrogen in the liquid   = 0.0165 (mole fraction)
K-values H2 / CH4 / C7   = 48.15 / 7.39 / 0.0082
Liquid / vapor density   = 633.2 / 7.60 kg/m3

DWSIM 10.2.11.0, generated 2026-10-08.

Property methods¶

How the package calculates each property, as it reports it in PropertyMethodsInfo (the property package editor shows the same list).

Property	Method
Vapor fugacity	Redlich-Kwong EOS
Liquid fugacity	Chao-Seader EOS
Vapor enthalpy, entropy, Cp/Cv	Lee-Kesler
Liquid enthalpy, entropy, Cp/Cv	Lee-Kesler
Vapor density	Lee-Kesler
Liquid density	Experimental / Rackett / COSTALD
Vapor viscosity	Experimental / Lucas / Jossi-Stiel-Thodos
Liquid viscosity	Experimental / Letsou-Stiel
Vapor thermal conductivity	Experimental / Ely-Hanley
Liquid thermal conductivity	Experimental / Latini
Surface tension	Experimental / Brock-Bird
Solid density	Experimental Data / User-Defined
Solid enthalpy, entropy, Cp/Cv	Experimental Solid Cp / From Liquid Phase Enthalpy + Enthalpy of Fusion

Default flash algorithm: Universal.

Configuration saved with the flowsheet¶

The package writes its settings to the simulation file (SaveData) and reads them back on load (LoadData). The elements below are the ones this package adds to those of every property package, as written for the example.

This package adds no elements of its own.

Settings common to every property package, as saved for the example

Element	Value
`Type`	63 characters
`ComponentName`	`Chao-Seader`
`ComponentDescription`
`Tag`	`Chao-Seader`
`UseHenryConstants`	`true`
`AutoEstimateMissingNRTLUNIQUACParameters`	`true`
`UseImmiscibleListForLiquid2InitialEstimates`	`true`
`SingleCompoundCheckThreshold`	`0.99999`
`OverrideKvalFugCoeff`	`false`
`OverrideEnthalpyCalculation`	`false`
`OverrideEntropyCalculation`	`false`
`LiquidDensityCalculationMode_Subcritical`	`Rackett_and_ExpData`
`LiquidDensityCalculationMode_Supercritical`	`Rackett_and_ExpData`
`LiquidDensity_CorrectExpDataForPressure`	`true`
`LiquidDensity_UsePenelouxVolumeTranslation`	`true`
`LiquidViscosityCalculationMode_Subcritical`	`ExpData`
`LiquidViscosityCalculationMode_Supercritical`	`Letsou_Stiel`
`LiquidViscosity_CorrectExpDataForPressure`	`true`
`LiquidViscosity_MixingRule`	`MoleAverage`
`VaporPhaseFugacityCalculationMode`	`Ideal`
`SolidPhaseFugacityCalculationMethod`	`FromLiquidFugacity`
`SolidPhaseFugacity_UseIdealLiquidPhaseFugacity`	`false`
`SolidPhaseEnthalpy_UsesCp`	`false`
`EnthalpyEntropyCpCvCalculationMode`	`LeeKesler`
`LiquidEnthalpyEntropyCpCvCalculationMode_EOS`	`EOS`
`LiquidFugacity_UsePoyntingCorrectionFactor`	`true`
`ActivityCoefficientModels_IgnoreMissingInteractionParameters`	`false`
`IgnoreVaporFractionLimit`	`false`
`IgnoreSalinityLimit`	`false`
`CalculateAdditionalMaterialStreamProperties`	`true`
`FlashCalculationApproach`	`NestedLoops`
`DisplayMissingCompoundPropertiesWarning`	`false`
`ForcedSolids`	`[]`
`PropertyOverrides`	`{}`
`FlashSettings`	36 `Setting` entries

Learn more¶

User guide
Used with

API members¶

Public members declared by this class. Inherited members are documented on the base classes.

Constructors¶

ChaoSeaderPropertyPackage()

C#VB.NET

public ChaoSeaderPropertyPackage()

Public Sub New()

ChaoSeaderPropertyPackage(bool)

Parameter	Type	Description
`comode`	`Boolean`

C#VB.NET

public ChaoSeaderPropertyPackage(bool comode)

Public Sub New(comode As Boolean)

Properties¶

ImplementsAnalyticalDerivatives

C#VB.NET

public override bool ImplementsAnalyticalDerivatives { get; }

Public Overrides ReadOnly Property ImplementsAnalyticalDerivatives As Boolean

MobileCompatible

C#VB.NET

public override bool MobileCompatible { get; }

Public Overrides ReadOnly Property MobileCompatible As Boolean

Methods¶

AUX_VAPDENS(double, double)

Parameter	Type	Description
`T`	`Double`
`P`	`Double`

C#VB.NET

public override double AUX_VAPDENS(double T, double P)

Public Overrides Function AUX_VAPDENS(T As Double, P As Double) As Double

AUX_Z(double[], double, double, PhaseName)

Parameter	Type	Description
`Vx`	`Double[]`
`T`	`Double`
`P`	`Double`
`state`	`PhaseName`

C#VB.NET

public override double AUX_Z(double[] Vx, double T, double P, PhaseName state)

Public Overrides Function AUX_Z(Vx As Double(), T As Double, P As Double, state As PhaseName) As Double

ConfigParameters()

C#VB.NET

public override void ConfigParameters()

Public Overrides Sub ConfigParameters()

dfidRbb_H(object, object, object, object, object, object, object, object)

Parameter	Type	Description
`Rbb`	`Object`
`Kb0`	`Object`
`Vz`	`Object`
`Vu`	`Object`
`sum_Hvi0`	`Object`
`DHv`	`Object`
`DHl`	`Object`
`HT`	`Object`

C#VB.NET

public double dfidRbb_H(object Rbb, object Kb0, object Vz, object Vu, object sum_Hvi0, object DHv, object DHl, object HT)

Public Function dfidRbb_H(Rbb As Object, Kb0 As Object, Vz As Object, Vu As Object, sum_Hvi0 As Object, DHv As Object, DHl As Object, HT As Object) As Double

dfidRbb_S(object, object, object, object, object, object, object, object)

Parameter	Type	Description
`Rbb`	`Object`
`Kb0`	`Object`
`Vz`	`Object`
`Vu`	`Object`
`sum_Hvi0`	`Object`
`DHv`	`Object`
`DHl`	`Object`
`ST`	`Object`

C#VB.NET

public double dfidRbb_S(object Rbb, object Kb0, object Vz, object Vu, object sum_Hvi0, object DHv, object DHl, object ST)

Public Function dfidRbb_S(Rbb As Object, Kb0 As Object, Vz As Object, Vu As Object, sum_Hvi0 As Object, DHv As Object, DHl As Object, ST As Object) As Double

DW_CalcCompPartialVolume(Phase, double, double)

Parameter	Type	Description
`phase`	`Phase`
`T`	`Double`
`P`	`Double`

C#VB.NET

public override void DW_CalcCompPartialVolume(Phase phase, double T, double P)

Public Overrides Sub DW_CalcCompPartialVolume(phase As Phase, T As Double, P As Double)

DW_CalcCp_ISOL(Phase, double, double)

Parameter	Type	Description
`Phase1`	`Phase`
`T`	`Double`
`P`	`Double`

C#VB.NET

public override double DW_CalcCp_ISOL(Phase Phase1, double T, double P)

Public Overrides Function DW_CalcCp_ISOL(Phase1 As Phase, T As Double, P As Double) As Double

DW_CalcCv_ISOL(Phase, double, double)

Parameter	Type	Description
`Phase1`	`Phase`
`T`	`Double`
`P`	`Double`

C#VB.NET

public override double DW_CalcCv_ISOL(Phase Phase1, double T, double P)

Public Overrides Function DW_CalcCv_ISOL(Phase1 As Phase, T As Double, P As Double) As Double

DW_CalcdKdT(double[], double[], double, double, string)

Parameter	Type	Description
`Vx`	`Double[]`
`Vy`	`Double[]`
`T`	`Double`
`P`	`Double`
`type`	`String`

C#VB.NET

public override double[] DW_CalcdKdT(double[] Vx, double[] Vy, double T, double P, string type = "LV")

Public Overrides Function DW_CalcdKdT(Vx As Double(), Vy As Double(), T As Double, P As Double, type As String = "LV") As Double()

DW_CalcdLnFugCoeffdT(double[], double, double, State): Temperature derivative of the natural logarithm of the fugacity coefficients, d(ln phi_i)/dT, for the given phase.

Temperature derivative of the natural logarithm of the fugacity coefficients, d(ln phi_i)/dT, for the given phase. Base implementation is a forward finite difference; EOS/activity packages override this with a closed-form expression. Distinct from DW_CalcdFugCoeffdT, which returns d(phi)/dT (not the logarithm).

Parameter	Type	Description
`Vx`	`Double[]`
`T`	`Double`
`P`	`Double`
`st`	`State`

C#VB.NET

public override double[] DW_CalcdLnFugCoeffdT(double[] Vx, double T, double P, State st)

Public Overrides Function DW_CalcdLnFugCoeffdT(Vx As Double(), T As Double, P As Double, st As State) As Double()

DW_CalcEnergyFlowMistura_ISOL(double, double)

Parameter	Type	Description
`T`	`Double`
`P`	`Double`

C#VB.NET

public override double DW_CalcEnergyFlowMistura_ISOL(double T, double P)

Public Overrides Function DW_CalcEnergyFlowMistura_ISOL(T As Double, P As Double) As Double

DW_CalcEnthalpy(Array, double, double, State): Calculates the enthalpy of a mixture.

Calculates the enthalpy of a mixture.

Parameter	Type	Description
`Vx`	`Array`	Vector of doubles containing the molar composition of the mixture.
`T`	`Double`	Temperature (K)
`P`	`Double`	Pressure (Pa)
`st`	`State`	State enum indicating the state of the mixture (liquid or vapor).

C#VB.NET

public override double DW_CalcEnthalpy(Array Vx, double T, double P, State st)

Public Overrides Function DW_CalcEnthalpy(Vx As Array, T As Double, P As Double, st As State) As Double

DW_CalcEnthalpyDeparture(Array, double, double, State): Calculates the enthalpy departure of a mixture.

Calculates the enthalpy departure of a mixture.

Parameter	Type	Description
`Vx`	`Array`	Vector of doubles containing the molar composition of the mixture.
`T`	`Double`	Temperature (K)
`P`	`Double`	Pressure (Pa)
`st`	`State`	State enum indicating the state of the mixture (liquid or vapor).

C#VB.NET

public override double DW_CalcEnthalpyDeparture(Array Vx, double T, double P, State st)

Public Overrides Function DW_CalcEnthalpyDeparture(Vx As Array, T As Double, P As Double, st As State) As Double

DW_CalcEntropy(Array, double, double, State): Calculates the entropy of a mixture.

Calculates the entropy of a mixture.

Parameter	Type	Description
`Vx`	`Array`	Vector of doubles containing the molar composition of the mixture.
`T`	`Double`	Temperature (K)
`P`	`Double`	Pressure (Pa)
`st`	`State`	State enum indicating the state of the mixture (liquid or vapor).

C#VB.NET

public override double DW_CalcEntropy(Array Vx, double T, double P, State st)

Public Overrides Function DW_CalcEntropy(Vx As Array, T As Double, P As Double, st As State) As Double

DW_CalcEntropyDeparture(Array, double, double, State): Calculates the entropy departure of a mixture.

Calculates the entropy departure of a mixture.

Parameter	Type	Description
`Vx`	`Array`	Vector of doubles containing the molar composition of the mixture.
`T`	`Double`	Temperature (K)
`P`	`Double`	Pressure (Pa)
`st`	`State`	State enum indicating the state of the mixture (liquid or vapor).

C#VB.NET

public override double DW_CalcEntropyDeparture(Array Vx, double T, double P, State st)

Public Overrides Function DW_CalcEntropyDeparture(Vx As Array, T As Double, P As Double, st As State) As Double

DW_CalcFugCoeff(Array, double, double, State): Calculates fugacity coefficients for the specified composition at the specified conditions.

Calculates fugacity coefficients for the specified composition at the specified conditions.

Parameter	Type	Description
`Vx`	`Array`	Vector of doubles containing the molar composition of the mixture.
`T`	`Double`	Temperature in K
`P`	`Double`	Pressure in Pa
`st`	`State`	Mixture state (Liquid or Vapor)

C#VB.NET

public override double[] DW_CalcFugCoeff(Array Vx, double T, double P, State st)

Public Overrides Function DW_CalcFugCoeff(Vx As Array, T As Double, P As Double, st As State) As Double()

DW_CalcK_ISOL(Phase, double, double)

Parameter	Type	Description
`Phase1`	`Phase`
`T`	`Double`
`P`	`Double`

C#VB.NET

public override double DW_CalcK_ISOL(Phase Phase1, double T, double P)

Public Overrides Function DW_CalcK_ISOL(Phase1 As Phase, T As Double, P As Double) As Double

DW_CalcMassaEspecifica_ISOL(Phase, double, double, double)

Parameter	Type	Description
`Phase1`	`Phase`
`T`	`Double`
`P`	`Double`
`Pvp`	`Double`

C#VB.NET

public override double DW_CalcMassaEspecifica_ISOL(Phase Phase1, double T, double P, double Pvp = 0)

Public Overrides Function DW_CalcMassaEspecifica_ISOL(Phase1 As Phase, T As Double, P As Double, Pvp As Double = 0) As Double

DW_CalcMM_ISOL(Phase, double, double)

Parameter	Type	Description
`Phase1`	`Phase`
`T`	`Double`
`P`	`Double`

C#VB.NET

public override double DW_CalcMM_ISOL(Phase Phase1, double T, double P)

Public Overrides Function DW_CalcMM_ISOL(Phase1 As Phase, T As Double, P As Double) As Double

DW_CalcOverallProps()

C#VB.NET

public override void DW_CalcOverallProps()

Public Overrides Sub DW_CalcOverallProps()

DW_CalcPhaseProps(Phase)

Parameter	Type	Description
`Phase`	`Phase`

C#VB.NET

public override void DW_CalcPhaseProps(Phase Phase)

Public Overrides Sub DW_CalcPhaseProps(Phase As Phase)

DW_CalcProp(string, Phase): Provides a wrapper function for CAPE-OPEN CalcProp/CalcSingleProp functions.

Provides a wrapper function for CAPE-OPEN CalcProp/CalcSingleProp functions.

Parameter	Type	Description
`property`	`String`	The property to be calculated.
`phase`	`Phase`	The phase where the property must be calculated for.

C#VB.NET

public override void DW_CalcProp(string property, Phase phase)

Public Overrides Sub DW_CalcProp([property] As String, phase As Phase)

DW_CalcPVAP_ISOL(double)

Parameter	Type	Description
`T`	`Double`

C#VB.NET

public override double DW_CalcPVAP_ISOL(double T)

Public Overrides Function DW_CalcPVAP_ISOL(T As Double) As Double

DW_CalcTensaoSuperficial_ISOL(Phase, double, double)

Parameter	Type	Description
`Phase1`	`Phase`
`T`	`Double`
`P`	`Double`

C#VB.NET

public override double DW_CalcTensaoSuperficial_ISOL(Phase Phase1, double T, double P)

Public Overrides Function DW_CalcTensaoSuperficial_ISOL(Phase1 As Phase, T As Double, P As Double) As Double

DW_CalcViscosidadeDinamica_ISOL(Phase, double, double)

Parameter	Type	Description
`Phase1`	`Phase`
`T`	`Double`
`P`	`Double`

C#VB.NET

public override double DW_CalcViscosidadeDinamica_ISOL(Phase Phase1, double T, double P)

Public Overrides Function DW_CalcViscosidadeDinamica_ISOL(Phase1 As Phase, T As Double, P As Double) As Double

IntegralSimpsonCp(double, double, double, string)

Parameter	Type	Description
`a`	`Double`
`b`	`Double`
`Epsilon`	`Double`
`subst`	`String`

C#VB.NET

public double IntegralSimpsonCp(double a, double b, double Epsilon, string subst)

Public Function IntegralSimpsonCp(a As Double, b As Double, Epsilon As Double, subst As String) As Double

IntegralSimpsonCp_T(double, double, double, string)

Parameter	Type	Description
`a`	`Double`
`b`	`Double`
`Epsilon`	`Double`
`subst`	`String`

C#VB.NET

public double IntegralSimpsonCp_T(double a, double b, double Epsilon, string subst)

Public Function IntegralSimpsonCp_T(a As Double, b As Double, Epsilon As Double, subst As String) As Double

RET_KIJ(string, string)

Parameter	Type	Description
`id1`	`String`
`id2`	`String`

C#VB.NET

public double RET_KIJ(string id1, string id2)

Public Function RET_KIJ(id1 As String, id2 As String) As Double

RET_VCSAc()

C#VB.NET

public double[] RET_VCSAc()

Public Function RET_VCSAc() As Double()

RET_VCSS()

C#VB.NET

public double[] RET_VCSS()

Public Function RET_VCSS() As Double()

RET_VKij()

C#VB.NET

public override double[,] RET_VKij()

Public Overrides Function RET_VKij() As Double(,)

RET_VVL()

C#VB.NET

public double[] RET_VVL()

Public Function RET_VVL() As Double()

SupportsComponent(ICompoundConstantProperties)

Parameter	Type	Description
`comp`	`ICompoundConstantProperties`

C#VB.NET

public override bool SupportsComponent(ICompoundConstantProperties comp)

Public Overrides Function SupportsComponent(comp As ICompoundConstantProperties) As Boolean

Fields¶

ClassId

C#VB.NET

public const string ClassId = "8079D263-219C-4df6-BB7D-D034DEE9C464"

Public Const ClassId As String = "8079D263-219C-4df6-BB7D-D034DEE9C464"

m_cs

C#VB.NET

public CS m_cs

Public m_cs As CS

m_lk

C#VB.NET

public LeeKesler m_lk

Public m_lk As LeeKesler

m_pr

C#VB.NET

public PengRobinson m_pr

Public m_pr As PengRobinson

MAT_KIJ

C#VB.NET

public object[,] MAT_KIJ

Public MAT_KIJ As Object(,)