Property Package Selection
This guide will help you on selecting the best Thermodynamic Model/Property Package for your system.
- 1 General Observations
- 2 Models by System Type
- 2.1 Non-polar gases at low pressures (< 10 atm)
- 2.2 Non-polar gases at high pressures (> 10 atm)
- 2.3 Polar gases at high pressures (> 10 atm)
- 2.4 Systems with high Hydrogen content
- 2.5 Air Separation / Refrigeration systems
- 2.6 Steam/Water simulations
- 2.7 Polar chemicals
- 2.8 Salt/Water systems
- 2.9 Aqueous Electrolytes
- 3 External Resources
Most thermodynamic models have binary interaction parameters which are fitted to match experimental data. Always check if the selected thermodynamic model has interaction parameters for the compounds in the simulation, if required. To view the list of IPs, open the Property Package Configuration Window and go to the Interaction Parameters tab.
Whenever possible, one should either use experimental data to check the predicted properties, or to use these data to fit suitable thermodynamic models. DWSIM has a tool to regress experimental data and calculate binary interaction parameters for various thermodynamic models. For more information, see <a href="http://dwsim.inforside.com.br/wiki/index.php?title=Using_the_Data_Regression_Utility" title="Using the Data Regression Utility">Using the Data Regression Utility</a>.
Models by System Type
Non-polar gases at low pressures (< 10 atm)
Use the Raoult's Law Property Package. It assumes that both phases (gas and liquid) are ideal.
Non-polar gases at high pressures (> 10 atm)
Use one of the Equation of State models like Peng-Robinson, Soave-Redlich-Kwong and PRSV2.
Polar gases at high pressures (> 10 atm)
Use the PRSV2 Property Package. Check if it has the required parameters for your system as DWSIM lacks many parameters for this model. If it doesn't, fallback to an EOS model like PR or SRK.
Systems with high Hydrogen content
You can use the Chao-Seader, Grayson-Streed or Lee-Kesler-Plöcker model. The LKP model is very slow but can be more reliable depending on the system. The LKP model is very sensitive to the interaction parameter values being used.
Air Separation / Refrigeration systems
Use the CoolProp or FPROPS Property Package.
Use the Steam Tables Property Package.
Use one of the activity coefficient models like NRTL or UNIQUAC. If no interaction parameters are available for your system, you can fallback to one of the UNIFAC-type models. Modified UNIFAC (NIST) is recommended.
Use the Seawater Property Package.
DWSIM has limited support for aqueous electrolytes due to the lack of model parameters. You can try the Extended UNIQUAC model, but be ready for many convergence errors. It may or may not work. If you don't need information about pH and/or don't care about precipitation of solids, you can always use one of the available activity coefficient models instead.