Applications of Complex Domain in Vapor−Liquid Equilibrium Calculations Using a Cubic Equation of State

• Published in: Industrial & engineering chemistry research Vol. 37; no. 5; pp. 1625 - 1633
• Main Authors: Zhao, Ensheng, Saha, Sanjoy
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Washington, DC American Chemical Society 04-05-1998
• Subjects: Chemical thermodynamics; Chemistry; Exact sciences and technology; General and physical chemistry; General. Theory; Liquid vapor equilibrium; Equations of state; Thermodynamic model; Phase equilibrium; Analytical method
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/ie970639k

A new method is proposed to identify the spurious root (density or compressibility) in a cubic equation of state when it is used for phase property calculations and also to evaluate the pseudo root for an unfeasible 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 into consideration in the development. A complete set of analytical expressions is developed for the implementation of the method. The validity of the method is demonstrated through examples. The proposed method is simple and easy to use. Moreover, the computational load involved in the implementation of the proposed method is minimal because no iterative strategy is required.