2.3 Results and discussion
2.3.1 Pure components
The pure component data, namely, the vapor pressure, saturated liquid densities
and liquid densities from PvT data were fitted to obtain the pure component param-
eters, chain length(m), segment diameter(σ) and the segment energy parameter(e/k).
These parameters were obtained for n-alkane series from n-C3 to n-C20. The re-
gression was done using Levenberg-Marquardt algorithm by minimizing the objective
function
№æ₽ z ∩exp _ Qcalc ∖ 2
F(m,σ,e∕k) = ∑U xpi ∖ , (2.30)
i=l × i '
where θi is the thermodynamic property, namely vapor pressure or saturated liquid
density or PvT data, considered for regression. Once the parameters were obtained,
the average absolute deviation (AAD%) was calculated for both vapor pressure and
saturated liquid density data. The parameters along with the AAD% are presented
in table 2.2.
The pure component vapor-liquid equilibria predictions of the new EOS are com-
pared to experimental data in figure 2.4 for selected n-alkanes. The temperature
range of the experimental data used for regression is the same as that used for de-
termining the PC-SAFT parameters for these components [48]. ADD% for both Psat
and puq for the new EOS are smaller than PC-SAFT for the n-alkanes considered.
Based on these parameters, the critical temperatures and pressures were computed.
48