An algorithm for convergent solutions in vapor–liquid equilibrium calculations using an equation of state

Lee, Ju Ho; Kang, Jeong Won; You, Seong Sik; Lee, Chul Soo

doi:10.1016/j.fluid.2005.05.009

Cited by 2 publications

(2 citation statements)

References 20 publications

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“…This feature also allows a fast and robust evaluation of the density root at the given pressure because there is no need for checking the additional Maxwell loop. Although an algorithm is available for solving a quintic EOS, the numerical solving for the density root is adopted for the present model.…”

Section: Results and Discussionmentioning

confidence: 99%

Development of an Accurate Quintic Equation of State: The Necessity of the Irreducible Quadratic Polynomial in the Attractive Term

Lee

Jeon

Lee

et al. 2015

Ind. Eng. Chem. Res.

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In conventional van der Waals type equation of state (EOS) modeling, the denominator of the attractive contribution is regarded as being a necessarily factorable quadratic polynomial for the closed-form expression of the corresponding Helmholtz free energy. This study evaluates the effect of the opposite case, irreducible quadratic polynomial, on the description of the volumetric behavior of real fluid through a comparison with the critical isotherm data, coexistence curve and PVT isotherm data. In a generalized cubic EOS, an irreducible quadratic polynomial was found to yield an improved description of the flattened region around the critical density while a nonclosed form of Helmholtz free energy is resulted. For an improved volumetric description using irreducible quadratic polynomial and a derivation of the closed-form of Helmholtz free energy, we developed a quintic EOS containing seven parameters, two of which are determined by correlating the critical isotherm data and others by regressing the sub and supercritical properties.In the description of the critical isotherms of nine pure compounds, a comparison with BenedictWebb-Robinson-Soave(BWRS) EOS showed that the present model exhibits slightly larger deviations than BWRS EOS, however, a good agreement was obtained with the reference model of REFPROP 8.0 in the description of the saturated vapor pressure, saturated density and PVT isotherm data over a wide range of temperature.

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Section: Results and Discussionmentioning

confidence: 99%

Development of an Accurate Quintic Equation of State: The Necessity of the Irreducible Quadratic Polynomial in the Attractive Term

Lee

Jeon

Lee

et al. 2015

Ind. Eng. Chem. Res.

Self Cite

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“…It can be overwritten by the Specific Packages, such as an analytic volume root-finding algorithm for CEOS. Non-CEOS could also have their special procedures for guessing the initial volume and other special treatments, such as how to handle the situation when no corresponding volume root exists for the specified phase status. − …”

Section: General Structurementioning

confidence: 99%

An Object-Oriented Approach for Structure Design of Property Calculation Programs Using Equations of State

Shi

2011

Ind. Eng. Chem. Res.

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A new object-oriented approach for designing general property calculation programs using different types of equations of state (EoS) is presented in this work. It helps to ease the programs' extensibility, reusability, and maintainability and, at the same time, minimize the code redundancy. The approach consists of two parts: (a) the total Helmholtz free energy function is separated into specific terms, based on physical meanings or mathematical expressions, independent of the properties of interest, and the same or similar specific terms used in different equations of state are abstracted to general algorithms; (b) the general relationships between these algorithms and the properties of interest are implemented at the highest level of the program. According to this strategy, a general cubic algorithm can be abstracted for all of the cubic EoS. The general hard-sphere, hard-chain, and association algorithms can be aggregated into different Statistical Associating Fluid Theory (SAFT) family EoS with different dispersion algorithms. Similarly, the general cubic and association algorithms can be aggregated into Cubic Plus Association (CPA) EoS. Taking Perturbed-Chain SAFT (PC-SAFT) EoS as an example, this manuscript demonstrates a clear object-oriented structure for developers, with regard to how to design a complete thermodynamic model package using this approach.

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An algorithm for convergent solutions in vapor–liquid equilibrium calculations using an equation of state

Cited by 2 publications

References 20 publications

Development of an Accurate Quintic Equation of State: The Necessity of the Irreducible Quadratic Polynomial in the Attractive Term

Development of an Accurate Quintic Equation of State: The Necessity of the Irreducible Quadratic Polynomial in the Attractive Term

An Object-Oriented Approach for Structure Design of Property Calculation Programs Using Equations of State

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