Calculation of Thermodynamic Properties of Real FluidsUsing 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

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

Other Programs

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 Peng-Robinson equation of state, how low pressure is allowed before the as should be recompressed

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

Solution

Methane 4 MPa, 120 oC

Cooler

Methane 4 MPa, 20 oC

Methane ?? MPa, 20 oC

Compressoradiabatic reversible

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