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Phase equilibria calculations with a modified redlich‐kwong equation of state
Author(s) -
Medani M. S.,
Hasan M. A.
Publication year - 1978
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.5450560214
Subject(s) - acentric factor , thermodynamics , equation of state , fugacity , isothermal process , enthalpy , chemistry , constant (computer programming) , phase (matter) , saturation (graph theory) , physics , mathematics , organic chemistry , combinatorics , computer science , programming language
A modified Redlich‐Kwong equation of state for pure substances in the liquid‐vapour coexisting phase region is suggested in which the fugacity coefficients of the two phases are equated and the resulting relationship is solved by assuming ω b to be temperature dependent while ω a remains constant. A generalised correlation for ω b is found with the acentric factor as a parameter. This approach is compared with the other two possible modifications, i.e. when ω a is a funtion of temperature while ω b is constant, and when both ω a and ω b are temperature dependent. Comparison revealed the excellent attainment of the equilibrium conditions when the proposed method is applied. Predicted volumetric properties and isothermal enthalpy departures of the liquid and vapour as well as the saturation vapour pressures are also compared which reveal the adequacy of the new modification. With the application of the mixing rules, the proposed modified equation is successfully applied to VLE calculations for binary mixtures of different complexities.