Fugacity Expressions Using the Peng-Robinson EoS

Any cubic equation of state can give an expression for the fugacity of species i in a gaseous or in liquid mixture. For example, the expression for the 

To calculate the fugacity of each species in a gaseous mixture using the above equation at specified T, P, and mole fractions of all components yi. y2., the following procedure is used 

Obtain the parameters a, and b, for each pure species (component) of the mixture from Equation 14.5. 

Solve the above cubic equation for the compressibility factor, zv 

Use the value of zv to compute the vapor phase fugacity for each species from Equation 14.9. 

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