Excel AddIn for Thermodynamic Calculations
Contents 
[edit] Introduction
The DWSIM Excel AddIn enables usage of some lowlevel internal functions in DWSIM, exposed so far only to CAPEOPEN compatible software. Some of the functions exposed include:
 Single Compound Property Calculator
 Single Phase Mixture Property Calculator
 PT, PH, PS, PVF and TVF 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 addin function.
[edit] Installation
The Excel addin is included within the DWSIM software package and can be installed using the normal procedure for XLL addins. Just look for the “DWSIM.xll” file in the DWSIM installation directory and you’re set:
[edit] Usage
Functions exposed by this addin will be grouped in a category named “DWSIM”:
Property and Equilibrium calculation functions require parameters that must be one or more values returned by GetPropPackList, GetCompoundList, GetPropList, GetCompoundPropList and GetPhaseList. They are selfexplanatory, 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:
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:
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.
[edit] 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 userdefinable interaction parameters for each Property Package:
Property Package 








PCSAFT 








PengRobinson (PR) 








SoaveRedlichKwong (SRK) 








PengRobinsonStryjekVera 2 (PRSV2) 








PengRobinson / LeeKesler (PR/LK) 








UNIFAC 








UNIFACLL 








Modified UNIFAC (Dortmund) 








NRTL 








UNIQUAC 








ChaoSeader 








GraysonStreed 








LeeKeslerPlöcker 








Raoult's Law 








COSMOSAC (JCOSMO) 








IAPWSIF97 Steam Tables 








[edit] Property Methods and Correlation Profiles
View the Property Methods and Correlation Profiles page for a list of Property Packages and their models/correlations used to calculate properties.
[edit] Flash Algorithms and Results Validation
[edit] 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 coexisting 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;
 InsideOut (2 or 3Phase): recommended for petroleum simulations. The 3phase option must be used when a second liquid phase is expected (i.e. free water);
 Gibbs Minimization (2 or 3phase): recommended for difficult, highly nonideal chemical systems;
 Nested Loops for Eutectic Solid Systems: Calculates SolidLiquid Equilibria for eutectic systems considering the solid phase as being ideal.
 Nested Loops for Solid Solution Systems: Calculates SolidLiquid Equilibria for solid solution systems considering the solid phase as being ideal.
 Nested Loops (3phase immiscible VLLE): Fast algorithm for systems with an immiscible second liquid phase (VLLE). The first compound in the list will be the immiscible one.
[edit] 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 threephase 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 AddIn 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 AddIn to validate the results.
For more details, download this Excel sheet which contains an example of a flash calculation validation.
[edit] Property Identifiers and Units
The following tables show the property identifiers and their units of measure as returned by the AddIn. The tables were copied directly from the CAPEOPEN 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 AddIn.
[edit] Single compound constant properties
Identifier  meaning  units 
acentricFactor  Pitzer acentric factor  
associationParameter  associationparameter (HaydenO’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  LennardJones 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  LennardJones 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 
[edit] Single compound temperaturedependent 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  Temperaturedependent 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  Selfdiffusion coefficient in gas phase at 1 atm  M2/s 
Identifier  Meaning  units 
selfDiffusionCoefficientLiquid  selfdiffusion 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 solidsolid 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 
[edit] Single compound pressuredependent properties
Identifier  Meaning  units 
boilingPointTemperature  Temperature at liquidvapour transition  K 
glassTransitionTemperature  Glass transition temperature  K 
meltingTemperature  Temperature on melting line  K 
solidSolidPhaseTransitionTemperature  Temperature at phase transition  K 
[edit] Nonconstant singlephase 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 