Songklanakarin Journal of Science and Technology (SJST) (Nov 2004)
UNIQUAC activity coefficient model and modified Redlich- Kwong EOS for the vapor liquid equilibrium systems of carbon dioxide-water
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 Redlich- Kwong 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.
