APPLICATIONS OF COMPLEX-DOMAIN IN VAPOR-LIQUID-EQUILIBRIUM CALCULATIONS USING A CUBIC EQUATION OF STATE

A new method is proposed to identify the spurious root (density or com pressibility) in a cubic equation of state when it is used for phase p roperty calculations and also to evaluate the pseudo root for an unfea sible phase specification based on a heuristic approach. The variation of real and real part of the complex roots with pressure for a cubic equation of state at constant temperature and composition is taken int o consideration in the development. A complete set of analytical expre ssions is developed for the implementation of the method. The validity of the method is demonstrated through examples. The proposed method i s simple and easy to use. Moreover, the computational load involved in the implementation of the proposed method is minimal because no itera tive strategy is required.