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06-‐321 ChemE Thermodynamics
Ge8ng Started with Aspen v8 Physical Property PredicCon
Bruno A. Calfa
Last Update: August 27th, 2014
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Aspen Products • Aspen Technology, or AspenTech, is a provider of soNware
and services for the process industries. • The AspenTech soNware suite includes
– Aspen Plus: steady-‐state simulator – Aspen Plus Dynamics: unsteady-‐state simulator – Aspen PIMS: producCon planning and opCmizaCon – Aspen Energy Analyzer: heat exchanger network design opCmizaCon – Aspen Economic Evalua9on: evaluaCon of capital investment – …
• Informally, engineers simply say “Aspen”. • Extensive databases and predicCon models of thermodynamic
and transport properCes è essenCal informaCon for rigorous simulaCon and opCmizaCon.
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Help with Aspen v8 • Web searches (Google it!). • Videos on YouTube
– h^ps://www.youtube.com/user/Lafaye^eChBE/playlists?shelf_id=7&sort=dd&view=50
– h^ps://www.youtube.com/user/evom1973/
Note: The graphical user interface (GUI) of Aspen products dramaCcally changed in version 8. It resembles MicrosoN Office products with the “ribbon style”.
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Opening Aspen Plus • Windows Start bu^on/menu -‐> Aspen Plus.
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IniCal Screen
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CreaCng a Simple Project • New -‐> Chemical Processes -‐> Chemicals with Metric (or English) Units.
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New Empty Project Screen
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Help Help
Ribbon
NavigaCon Pane
Environment Bu^ons
See video for details: h^ps://www.youtube.com/watch?v=en6ZQxnDtI4
Property PredicCon Task • Predict the molar volume of ethane at two condiCons:
– CondiCon 1: P = 1 atm, T = 573.15 K – CondiCon 2: P = 20 atm, T = 298.15 K
• Is the Ideal Gas Law a reasonable assumpCon?
CondiCon 1: V = 47,031.23 mL/mol CondiCon 2: V = 1,223.27 mL/mol
• More rigorous EquaCon of State (EoS) models may be more appropriate depending on the system condiCons.
• Use Aspen to predict the volume for the two condiCons above using an appropriate EoS model.
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Specifying Component(s) • “Find” ethane and add it to the list of components.
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Component Specified • Note change in status (no red symbols) aNer component is added.
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Specify Method • Click on Methods folder. Use Method Assistant.
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Method Assistant • Follow steps: Specify component type -‐> Hydrocarbon system -‐> No.
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Select Appropriate Method • Let us use Peng-‐Robinson EoS model (PENG-‐ROB).
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Pure Component Property • In the Home tab, Analysis task, click on Pure.
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Enter InformaCon for CondiCon 1 • Property V, unit ml/mol, vapor, T, and P. • Click on Run Analysis (green bu^on).
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Results for CondiCon 1 • By default, plot is shown (useful if range of T is given). • Click on item Results under PURE-‐1 subfolder under Analysis folder.
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Enter InformaCon for CondiCon 2 • Click on Pure bu^on again and enter the informaCon for CondiCon 2. • Click on Run Analysis (green bu^on).
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Results for CondiCon 2 • By default, plot is shown (useful if range of T is given). • Click on item Results under PURE-‐2 subfolder under Analysis folder.
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Summary of PredicCons
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• Molar volumes [mL/mol]
• Similar results for CondiCon 1. • For CondiCon 2, Ideal Gas Law overesCmates V by 23% when
compared to PENG-‐ROB. Why? – High pressure, “low” temperature è intermolecular interacCons are
not negligible anymore. Need more rigorous model for more accurate predicCons.
• See file VolumePredicCon.apwz.
Ideal Gas Law PENG-‐ROB
CondiCon 1 47,031.23 46,988.73
CondiCon 2 1,223.27 994.07