This method is used to calculate the natural logarithm of the fugacity coefficients (and optionally their derivatives) in a single Phase mixture. The values of temperature, pressure and composition are specified in the argument list and the results are also returned through the argument list.

Namespace: DWSIM.Thermodynamics.Streams
Assembly: DWSIM.Thermodynamics (in DWSIM.Thermodynamics.dll) Version: 8.8.1.0

Syntax

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public void CalcAndGetLnPhi(
	string phaseLabel,
	double temperature,
	double pressure,
	Object moleNumbers,
	int fFlags,
	ref Object lnPhi,
	ref Object lnPhiDT,
	ref Object lnPhiDP,
	ref Object lnPhiDn
)

Public Sub CalcAndGetLnPhi ( 
	phaseLabel As String,
	temperature As Double,
	pressure As Double,
	moleNumbers As Object,
	fFlags As Integer,
	ByRef lnPhi As Object,
	ByRef lnPhiDT As Object,
	ByRef lnPhiDP As Object,
	ByRef lnPhiDn As Object
)

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Parameters

phaseLabel String: Phase label of the Phase for which the properties are to be calculated. The Phase label must be one of the strings returned by the GetPhaseList method on the ICapeThermoPhases interface.
temperature Double: The temperature (K) for the calculation.
pressure Double: The pressure (Pa) for the calculation.
moleNumbers Object: Number of moles of each Compound in the mixture.
fFlags Int32: Code indicating whether natural logarithm of the fugacity coefficients and/or derivatives should be calculated (see notes).
lnPhi Object: Natural logarithm of the fugacity coefficients (if requested).
lnPhiDT Object: Derivatives of natural logarithm of the fugacity coefficients w.r.t. temperature (if requested).
lnPhiDP Object: Derivatives of natural logarithm of the fugacity coefficients w.r.t. pressure (if requested).
lnPhiDn Object: Derivatives of natural logarithm of the fugacity coefficients w.r.t. mole numbers (if requested).

Implements

ICapeThermoPropertyRoutine.CalcAndGetLnPhi(String, Double, Double, Object, Int32, Object, Object, Object, Object)

Remarks

This method is provided to allow the natural logarithm of the fugacity coefficient, which is the most commonly used thermodynamic property, to be calculated and returned in a highly efficient manner. The temperature, pressure and composition (mole numbers) for the calculation are specified by the arguments and are not obtained from the Material Object by a separate request. Likewise, any quantities calculated are returned through the arguments and are not stored in the Material Object. The state of the Material Object is not affected by calling this method. It should be noted however, that prior to calling CalcAndGetLnPhi a valid Material Object must have been defined by calling the SetMaterial method on the ICapeThermoMaterialContext interface of the component that implements the ICapeThermoPropertyRoutine interface. The compounds in the Material Object must have been identified and the number of values supplied in the moleNumbers argument must be equal to the number of Compounds in the Material Object. The fugacity coefficient information is returned as the natural logarithm of the fugacity coefficient. This is because thermodynamic models naturally provide the natural logarithm of this quantity and also a wider range of values may be safely returned. The quantities actually calculated and returned by this method are controlled by an integer code fFlags. The code is formed by summing contributions for the property and each derivative required using the enumerated constants eCapeCalculationCode (defined in the Thermo version 1.1 IDL) shown in the following table. For example, to calculate log fugacity coefficients and their T-derivatives the fFlags argument would be set to CAPE_LOG_FUGACITY_COEFFICIENTS + CAPE_T_DERIVATIVE. code numerical value no calculation CAPE_NO_CALCULATION 0 log fugacity coefficients CAPE_LOG_FUGACITY_COEFFICIENTS 1 T-derivative CAPE_T_DERIVATIVE 2 P-derivative CAPE_P_DERIVATIVE 4 mole number derivatives CAPE_MOLE_NUMBERS_DERIVATIVES 8 If CalcAndGetLnPhi is called with fFlags set to CAPE_NO_CALCULATION no property values are returned. A typical sequence of operations for this method when implemented by a Property Package component would be: - Check that the phaseLabel specified is valid. - Check that the moleNumbers array contains the number of values expected (should be consistent with the last call to the SetMaterial method). - Calculate the requested properties/derivatives at the T/P/composition specified in the argument list. - Store values for the properties/derivatives in the corresponding arguments. Note that this calculation can be carried out irrespective of whether the Phase actually exists in the Material Object.

Reference

MaterialStream Class

DWSIM.Thermodynamics.Streams Namespace