Calculation of Thermodynamic Properties of Real Fluids
Using Peng-Robinson EoS Program Provided by
Professor S.I. Sandler
Installation of Visual Basic Program
 Access the CD drive and click "OPEN".
 This should open a listing of the folders on the CD, named for
the assets they contain.
 Select the folder "VISUAL BASIC PROGRAMS"
 Select the folder "Property package"
 Select the icon "setup.exe" and follow the installation instruction.
 This program will allow you to access properties of pure components
 Go back to the folder "Peng Robinson Package"
 Select the icon "setup.exe" and follow the installation instruction.
This program will allow you to calculate thermodynamic properties and VLE of
pure fluid using the Peng-Robinson equation of states
Other Programs
 You can install other programs in a similar manner
 Peng-Robinson for mixtures
 Modified UNIFAC
 Chemical Equilibirum
 A folder "sandler" will appear on the "startup" menu
Ex. 6.65
 Pipelines are used to transport natural gas over thousands of miles with
compressors (pumping stations) at regular intervals along the pipeline to
compensate for the pressure drop due to flow.
 Because of the long distance and good heat transfer, the gas remains at
ambient temperature of 20oC
 At the pumping station the gas is compressed with a single stage
compressor to 4 MPa and then isobarically cooled back to 20 oC
 Because of safety and equipment constraints, the gas temperature
during compression should not exceed 120 oC
 Assuming that the natural gas is methane that is described by the PengRobinson equation of state, how low pressure is allowed before the as
should be recompressed
Solution
Methane
4 MPa, 120 oC
Methane
4 MPa, 20 oC
Cooler
Methane
?? MPa, 20 oC
Compressor
adiabatic
reversible
 Find entropy of methane at 4 MPa and 120oC
 Assume the compression is isenthropic
 Find the pressure of methane at 20 oC that have the same entropy as
methane at at 4 MPa and 120oC
 Activate the "startup" menu and run the "sandler"--"Peng Robinson
equation of state"
 The following window will popup
 Click on "Find Component"
 Type "methane"
 Accept
 The critical properties of methane will appear
 Calculate properties of methane at 120 oC and 4 MPa using filling in the
conditions and pressing the button "Calculate EOS"
 Entropy of methane at 120 oC and 4 MPa is found to be -21 J/(kmol K)
 Calculate the entropy of methane at 20 oC and different pressure
 The entropy of methane at 20 oC was found to be -21 J/(kmol K) at ~11
MPa