Excel Add-In for Thermodynamic Calculations

Introduction

The DWSIM Excel Add-In exposes some of the internal Thermodynamic Property Calculation Routines to Microsoft Excel, including:

• Single Compound Properties (i.e. Boiling Point, Heat Capacity, Viscosity...)
• Single Phase Mixture Properties (i.e. Enthalpy, Entropy, Molar Weight, Thermal Conductivity, Viscosity...)
• Pressure-Temperature, Pressure-Enthalpy, Pressure-Entropy, Pressure-VaporFraction and Temperature-VaporFraction Flash Calculators, using an algorithm of your choice
• Other auxiliary functions

Property and Equilibrium calculation functionality is now available to Excel just as any other add-in function.

Installation

The Excel Add-In is part of DWSIM Simulator for Windows Desktop - <a href="/wiki/index.php?title=Downloads" title="Downloads">you must install it first</a>.

Remember the location where DWSIM was installed, as you'll use this location to find the Add-In XLL file.

After installing DWSIM, open Excel and go to File > Options > Add-Ins > Manage (Excel Add-Ins) > Go > Browse. More information: <a rel="nofollow" class="external text" href="https://support.office.com/en-us/article/add-or-remove-add-ins-in-excel-0af570c4-5cf3-4fa9-9b88-403625a0b460">Add or remove add-ins in Excel</a>

Look for DWSIM.xll in DWSIM's installation directory if you're running the 32-bit Excel version, otherwise look for for DWSIM_64.xll if you're running the 64-bit version.

Usage

Functions exposed by this add-in will be grouped in a category named DWSIM:

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Property and Equilibrium calculation functions require parameters that must be one or more values returned by GetPropPackList, GetCompoundList, GetPropList, GetCompoundPropList and GetPhaseList. They are self-explanatory, and will return values listed in a single column, so you probably will have to select some cells in a single column and call the functions using Ctrl+Shift+Enter:

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For example, the PTFlash function requires the name of the Property Package to use, the compound names and mole fractions, temperature in K, pressure in Pa and you may optionally provide new interaction parameters that will override the ones used internally by DWSIM. The calculation results will be returned as a (n+2) x (4) matrix, where n is the number of compounds. First row will contain the phase names (Vapor, Liquid, Liquid2 and Solid, in this order), the second will contain the phase mole fractions and the other lines will contain the compound mole fractions in the corresponding phases:

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For PH, PS, TVF and PVF flash calculation functions, and additional line is returned that will contain the temperature in K or pressure in Pa in the first column.

Overriding Interaction Parameters

You can directly override the interaction parameters used by Property Packages when calling calculations from Excel by providing n x n matrices containing the values, where n is the number of compounds. This feature is optional and should be used only when you know exactly what you are doing.

The following table shows the user-definable interaction parameters for each Property Package:

Property Package	IP Set #1	IP Set #2	IP Set #3	IP Set #4	IP Set #5	IP Set #6	IP Set #7	IP Set #8
PC-SAFT	PC-SAFT kij	Not used	Not used	Not used	Not used	Not used	Not used	Not used
Peng-Robinson (PR)	PR kij	Not used	Not used	Not used	Not used	Not used	Not used	Not used
Soave-Redlich-Kwong (SRK)	SRK kij	Not used	Not used	Not used	Not used	Not used	Not used	Not used
Peng-Robinson-Stryjek-Vera 2 (PRSV2)	PRSV2-M kij	PRSV2-M kji	Not used	Not used	Not used	Not used	Not used	Not used
Peng-Robinson / Lee-Kesler (PR/LK)	PR kij	Not used	Not used	Not used	Not used	Not used	Not used	Not used
UNIFAC	PR kij	Not used	Not used	Not used	Not used	Not used	Not used	Not used
UNIFAC-LL	PR kij	Not used	Not used	Not used	Not used	Not used	Not used	Not used
Modified UNIFAC (Dortmund)	PR kij	Not used	Not used	Not used	Not used	Not used	Not used	Not used
NRTL	PR kij	NRTL A12 (cal/mol)	NRTL A21 (cal/mol)	NRTL Alpha	NRTL B12 (cal/mol.K)	NRTL B21 (cal/mol.K)	NRTL C12 (cal/mol.K²)	NRTL C21 (cal/mol.K²)
UNIQUAC	PR kij	UNIQUAC A12 (cal/mol)	UNIQUAC A21 (cal/mol)	UNIQUAC B12 (cal/mol.K)	UNIQUAC B21 (cal/mol.K)	UNIQUAC C12 (cal/mol.K²)	UNIQUAC C21 (cal/mol.K²)	Not used
Chao-Seader	Not used	Not used	Not used	Not used	Not used	Not used	Not used	Not used
Grayson-Streed	Not used	Not used	Not used	Not used	Not used	Not used	Not used	Not used
Lee-Kesler-Plöcker	LKP kij	Not used	Not used	Not used	Not used	Not used	Not used	Not used
Raoult's Law	Not used	Not used	Not used	Not used	Not used	Not used	Not used	Not used
COSMO-SAC (JCOSMO)	PR kij	Not used	Not used	Not used	Not used	Not used	Not used	Not used
IAPWS-IF97 Steam Tables	Not used	Not used	Not used	Not used	Not used	Not used	Not used	Not used

Property Methods and Correlation Profiles

View the <a href="/wiki/index.php?title=Property_Methods_and_Correlation_Profiles" title="Property Methods and Correlation Profiles">Property Methods and Correlation Profiles</a> page for a list of Property Packages and their models/correlations used to calculate properties.

Flash Algorithms and Results Validation

Flash Algorithms

The Flash Algorithms in DWSIM are the components responsible for determining a particular set of phases at thermodynamic equilibrium, their amounts (and the amounts of the compounds on each phase) at the specified conditions like Temperature, Pressure, Total Enthalpy and Total Entropy. Some Flash Algorithms are capable of predicting equilibrium between one vapor and one liquid phase, while others support another co-existing liquid and/or solid phase. As the amount of phases considered in equilibrium increases, the calculation time/complexity also increases while the results' reliability decreases.

Some flash algorithms are more capable/reliable than others, depending on the mixture for which the flash calculation request is being requested. DWSIM features a selection of flash algorithms that are capable of calculating VLE, VLLE and SLE. They are:

• Nested Loops (default): recommended for the vast majority of VLE systems;

• Nested Loops (VLLE): recommended for mixtures which exhibit liquid phase splitting;

• Inside-Out (2 or 3-Phase): recommended for petroleum simulations. The 3-phase option must be used when a second liquid phase is expected (i.e. free water);

• Gibbs Minimization (2 or 3-phase): recommended for difficult, highly non-ideal chemical systems;

• Nested Loops for Eutectic Solid Systems: Calculates Solid-Liquid Equilibria for eutectic systems considering the solid phase as being ideal.

• Nested Loops for Solid Solution Systems: Calculates Solid-Liquid Equilibria for solid solution systems considering the solid phase as being ideal.

• Nested Loops (3-phase immiscible VLLE): Fast algorithm for systems with an immiscible second liquid phase (VLLE). The first compound in the list will be the immiscible one.

Validation of Equilibrium Calculations

Not all thermodynamic models are adequate for all types of mixtures/systems. It is easy to be mistaken by an apparently suitable model for your system because it will always return a result, which may be correct or not depending on a number of factors:

• Inadequate/limited background theory for thermodynamic calculations
• Missing binary interaction parameters (BIPs)
• Unsuitable flash algorithm

You must know a priori what to expect from a flash calculation. For example, for a mixture of hydrocarbons with water, a liquid phase split is expected because water and hydrocarbons are almost completely immiscible. In this case a VLE Flash Algorithm is not suitable for equilibrium calculations. You must use one of the three-phase flash algorithms available.

Validation of flash results is carried out automatically by DWSIM if you're doing a simulation through its own interface, but if you're using the Excel Add-In you must take some extra precautions to understand what's being given as a result.

To validate the equilibrium calculation results, you can take advantage of the fact that the Gibbs Free Energy will always decrease on a phase split. If there's no phase split, the Gibbs energy will remain the same, otherwise it must decrease. Using the definition G = H - TS (Gibbs Energy = Enthalpy - Temperature x Entropy), you can use the available functions in the DWSIM Excel Add-In to validate the results.

For more details, <a rel="nofollow" class="external text" href="http://sourceforge.net/projects/dwsim/files/DWSIM/DWSIM%203.0/Flash%20Calculation%20Validation.xls/download">download this Excel sheet</a> which contains an example of a flash calculation validation.

Property Identifiers and Units

The following tables show the property identifiers and their units of measure as returned by the Add-In. The tables were copied directly from the CAPE-OPEN Thermo 1.1 standard document.

Please note that not all properties are implemented in DWSIM – if you ask for a property that is not available, a NotImplemented exception will be returned by the Add-In.

Single compound constant properties

Identifier	meaning	units
acentricFactor	Pitzer acentric factor
associationParameter	association-parameter (Hayden-O’Connell)
bornRadius		m
charge
criticalCompressibilityFactor	critical compressibility factor Z
criticalDensity	critical density	mol/m3
criticalPressure	critical pressure	Pa
criticalTemperature	critical temperature	K
criticalVolume	critical volume	m3/mol
diffusionVolume	diffusion volume	m3
dipoleMoment	dipole moment	Cm
energyLennardJones	Lennard-Jones energy parameter (divided by Boltzmann constant)	K
gyrationRadius	radius of gyration	m
heatOfFusionAtNormalFreezingPoint	enthalpy change on melting at normal freezing point (101325 Pa)	J/mol
heatOfVaporizationAtNormalBoilingPoint	enthalpy change on vaporization at normal boiling point (101325 Pa)	J/mol
idealGasEnthalpyOfFormationAt25C		J/mol
idealGasGibbsFreeEnergyOfFormationAt25C		J/mol
liquidDensityAt25C	liquid density at 25 ºC	mol/m3
liquidVolumeAt25C	liquid volume at 25 ºC	m3/mol
lengthLennardJones	Lennard-Jones length parameter	m
molecularWeight	relative molar mass
normalBoilingPoint	boiling point temperature at 101325 Pa	K
normalFreezingPoint	melting point temperature at 101325 Pa	K
Identifier	meaning	units
parachor	Parachor	m3 kg0.25/(s0.5 mol)
standardEntropyGas	Standard entropy of gas	J/mol
standardEntropyLiquid	standard entropy of liquid	J/mol
standardEntropySolid	standard entropy of solid	J/mol
standardEnthalpyAqueousDilution	Standard aqueous infinite dilution enthalpy	J/mol
standardFormationEnthalpyGas	standard enthalpy change on formation of gas	J/mol
standardFormationEnthalpyLiquid	standard enthalpy change on formation of liquid	J/mol
standardFormationEnthalpySolid	standard enthalpy change on formation of solid	J/mol
standardFormationGibbsEnergyGas	standard Gibbs energy change on formation of gas	J/mol
standardFormationGibbsEnergyLiquid	standard Gibbs energy change on formation of liquid	J/mol
standardFormationGibbsEnergySolid	standard Gibbs energy change on formation of solid	J/mol
standardGibbsAqueousDilution	Standard aqueous infinite dilution Gibbs energy	J/mol
triplePointPressure	triple point pressure	Pa
triplePointTemperature	triple point temperature	K
vanderwaalsArea	van der Waals area	m2
vanderwaalsVolume	van der Waals volume	m3

Single compound temperature-dependent properties

Identifier	Meaning	units
cpAqueousInfiniteDilution	Heat capacity of a solute in an infinitely dilute aqueous solution.	J/(mol K)
dielectricConstant	The ratio of the capacity of a condenser with a particular substance as dielectric to the capacity of the same condenser with a vacuum for dielectric.
expansivity	Coefficient of linear expansion for a solid:	1/K
	(where L is the length) at 1 atm
fugacityCoefficientOfVapor	Fugacity coefficient of vapour on the saturation line
glassTransitionPressure	Glass transition pressure	Pa
heatCapacityOfLiquid	Heat capacity (Cp) of liquid on the saturation line	J/(mol K)
heatCapacityOfSolid	Solid heat capacity (Cp) at 1 atm	J/(mol K)
heatOfFusion	Enthalpy change on fusion for the solid on the melting line	J/mol
heatOfSublimation	Enthalpy change on evaporation of the solid on the sublimation line	J/mol
heatOfSolidSolidPhaseTransition	Enthalpy change on phase transition	J/mol
heatOfVaporization	Enthalpy change on evaporation of the liquid on the saturation line	J/mol
idealGasEnthalpy	Enthalpy of ideal gas	J/mol
idealGasEntropy	Temperature-dependent part of entropy of ideal gas	J/(mol K)
idealGasHeatCapacity	Heat capacity (Cp) of ideal gas	J/(mol K)
meltingPressure	Pressure on melting line	Pa
selfDiffusionCoefficientGas	Self-diffusion coefficient in gas phase at 1 atm	M2/s
Identifier	Meaning	units
selfDiffusionCoefficientLiquid	self-diffusion coefficient in liquid phase on saturation line	M2/s
solidSolidPhaseTransitionPressure	Pressure at phase transition	Pa
sublimationPressure	Vapour pressure of solid on the sublimation line	Pa
surfaceTensionSatLiquid	Surface tension of liquid on the saturation line	N/m
thermalConductivityOfLiquid	Thermal conductivity of liquid on saturation line	W/(m K)
thermalConductivityOfSolid	Thermal conductivity of solid at 1 atm	W/(m K)
thermalConductivityOfVapor	Thermal conductivity of dilute gas	W/(m K)
vaporPressure	Vapour pressure of saturated liquid	Pa
virialCoefficient	Second virial coefficient of gas	M3/mol
viscosityOfLiquid	Viscosity of liquid on saturation line	Pas
viscosityOfVapor	Viscosity in dilute gas state	Pas
volumeChangeUponMelting	Volume change for the solid on the melting line	m3/mol
volumeChangeUponSolidSolidPhaseTransition	Volume change upon solid-solid phase transition	m3/mol
volumeChangeUponSublimation	Volume change for the solid on the sublimation line	m3/mol
volumeChangeUponVaporization	Volume change for the liquid on the saturation line	m3/mol
volumeOfLiquid	Volume of liquid on saturation line	m3/mol
volumeOfSolid	Volume of solid at 1 atm	m3/mol

Single compound pressure-dependent properties

Identifier	Meaning	units
boilingPointTemperature	Temperature at liquid-vapour transition	K
glassTransitionTemperature	Glass transition temperature	K
meltingTemperature	Temperature on melting line	K
solidSolidPhaseTransitionTemperature	Temperature at phase transition	K

Non-constant single-phase mixture properties

Identifier	Meaning	units	basis	overall
activity	Activity		U
activityCoefficient	Activity coefficient		U
compressibility	Isothermal compressibility	1/Pa	U
compressibilityFactor	Compressibility factor		U	Y
density	Density	mol/m3	mole/mass	Y
diffusionCoefficient	Binary diffusion coefficients for all species in mixture relative to all other species	m2/s	U
dissociationConstant	Chemical equilibrium constant corresponding to a dissociation reaction.		U
enthalpy	Enthalpy	J	mole/mass	Y
entropy	Entropy	J/K	mole/mass	Y
excessEnthalpy	Excess enthalpy	J	mole/mass
excessEntropy	Excess entropy	J/K	mole/mass
excessGibbsEnergy	Excess Gibbs energy	J	mole/mass
excessHelmholtzEnergy	Excess Helmholtz energy	J	mole/mass
excessInternalEnergy	Excess internal energy	J	mole/mass
excessVolume	Excess volume	m3	mole/mass
flow	Flows of each Compound in a given Phase (or the overall mixture)	mol/s	mole/mass	Y
fraction	Molar (or mass) fractions of each Compound in a given Phase (or the overall mixture)		mole/mass	Y
fugacity	Fugacity	Pa	U
fugacityCoefficient	Fugacity coefficient		U
gibbsEnergy	Gibbs energy	J	mole/mass	Y
heatCapacityCp	Heat capacity at constant pressure (Cp)	J/K	mole/mass	Y
heatCapacityCv	Heat capacity at constant volume (Cv)	J/ K	mole/mass	Y
helmholtzEnergy	Helmholtz energy	J	mole/mass	Y
internalEnergy	Internal energy	J	mole/mass	Y
jouleThomsonCoefficient		K/Pa	U
logFugacity	Natural logarithm of fugacity (expressed in Pa)		U
logFugacityCoefficient	Natural logarithm of fugacity coefficient		U
meanActivityCoefficient	The geometrical mean of the activity coefficients of the ions in an electrolyte solution.		U
molecularWeight	Mixture average molecular weight (relative molar mass)		U
pH	pH		U
pOH	pOH		U
phaseFraction	The molar (or mass) fraction of the fluid that is in the specified phase		mole/mass
pressure	Pressure	Pa	U	Y
speedOfSound	Thermodynamic speed of sound	m/s	U
temperature	Temperature	K	U	Y
thermalConductivity	Thermal conductivity	W/(m K)	U
totalFlow	Matter flow of a Phase or the overall mixture	mol/s	mole/mass	Y
viscosity	Viscosity	Pa s	U
volume	Volume	m3	mole/mass	Y