Construction of phase envelopes for binary and multicomponent mixtures with Euler-Newton predictor-corrector methods

Abstract

New algorithms for the calculation of constant composition phase envelopes of binary and multicomponent mixtures and constant temperature (P-x,y), constant pressure (T-x,y) phase diagrams of binary mixtures are presented. The proposed numerical methods are Euler-Newton predictor-corrector methods that sequentially trace the entire family of solutions (phase diagrams), corresponding to given specifications. Different sets of independent variables are used for the sequential calculation of constant composition phase envelopes of mixtures and the resulting methods are compared. The variable set that shows the best behavior in terms of efficiency, robustness and conditioning is utilized subsequently in constructing new methods that trace phase diagrams of binary mixtures at constant temperature or pressure. In this case, the methods are based on different combinations of thermodynamic equations and are evaluated with respect to the condition number of the corresponding Jacobian matrix and the ability to trace different types of phase diagrams.