II. Prediction of component fugacities and related properties of mixtures

Abstract

AbstractA computer program based on the theory of Part I is developed for calculating equilibrium ratios and related thermodynamic properties of mixtures, and a variety of data are used to test the method. For the carbon dioxide‐n‐butane system both liquid and gaseous compressibility factors are predicted with an average absolute deviation from experimental values of 1.3% for a wide range of conditions. A maximum deviation of 5.4% occurs in the critical region. Derivative properties such as component fugacities and equilibium ratios show somewhat larger deviations as expected. For the same system average deviations are 2.7% for carbon dioxide fugacities, 2.6% for n‐butane fugacities, and 3.3% for carbon dioxide and n‐butane equilibrium ratios. Average deviation for predicted equilibrium ratios for eight binary systems and 574 data points is 4.6%. Equilibrium ratios for two ternary systems are also predicted accurately. The major advantage of the method, however, is the small or negligible amount of experimental mixture data required. The method has not been tested below a mixture reduced temperature of 0.8, the lower limit of the Pitzer tables. Without density corrections to the scaling parameters best results are obtained if all binary pairs in a mixture fall within range 0.25 <VCj TCj/VCi TCi < 4.0.