Lupong Kaewsichan, Katawut Keowkrai and Nurak Grisdanurak

pp. 907 - 916

Abstract

The UNIQUAC activity coefficient model and fugacity coefficient model of modified Redlich-Kwong
predicted vapor-liquid equilibrium between carbon dioxide and water efficiently. The activity coefficient
model needed the energy interaction parameters between molecules of carbon dioxide and water. Those
parameters can be obtained by non-linear regression method of the experimental data of the vapor-liquid
equilibria of carbon dioxide and water (Lide, 1992). The fugacity coefficient model of modified RedlichKwong needed only some physical properties of carbon dioxide and water without any interaction parameters. The experimental data had ranges of temperature and partial pressure of carbon dioxide between
10 to 100ºC and 5 to 1,200 kPa, respectively. The parameters for the activity coefficient model are temperature dependent but are not concentration dependent. The regression results gave good agreements with
the experimental data in which the mean absolute error (MAE) between experiment and calculated partial
pressure of carbon dioxide was 2.72% and the mean absolute standard deviation (MAD) of that error was
1.35%. Comparing the effects of activity coefficients and fugacity coefficients, we found that the non-ideality
in vapor phase was more influential than the non-ideality in liquid phase.

Keywords

• carbon dioxide
• UNIQUAC
• modified Redlich-Kwong
• VLE