liquid density of mixtures, Peneloux vs. extended EOS

[mrbabu]

To simulate a pipeline I am calculating several tables with values of liquid densities (for generic hydrocarbon mixtures C1...C13) at different temperature and pressures (up to 35 C and 60 Bar),

I use PRODE PROPERTIES and Excel,

the method = EStrLD(stream,t,p)

returns directly the calculated liquid density at specified temperature and pressure,

for liquid density PRODE allows to select different models as Extended PR or SRK or a EOS with Peneloux correction,
according my tests it seems that Extended PR or Extended SRK are more accurate that equivalent versions with Peneloux correction,
this is has been confirmed in another forum

for liquid densities with EOS PRODE PROPERTIES allows three options (in addition to std. version which calculates density and volume from EOS),

1) std. version with Peneloux correction (available for both Peng Robinson and Soave Redlich Kwong EOS)

2) extended EOS with 3 parameters calculated to fit vapor pressure, heat capacity and liquid density of each pure component

3) extended EOS with 5 parameters calculated to fit vapor pressure, heat capacity and liquid density of each pure component

option 2) is available for SRK, PR, CPA etc. in base version

option 3) is available for SRK, PR, CPA etc. in extended versions

option 1) is the less accurate (but better than density calculated from EOS without correction)

option 2) is accurate (generally within 5%) for most hydrocarbons

option 3) is the most accurate

in Excel you can calculate the density at specified temperature and pressure by entering the macro

=EStrLD(stream,t,p)

this macro solves phase equilibria at specified t and p and then returns the liquid density calculated with selected models.

so for these cases I would recommend to select the Extended EOS option

[carlo.stenali]

thanks mrbabu for the information