G.H.PATEL COLLEGE OF ENGINEERING AND TECHNOLOGY Chemical Engineering Thermodynamics-2 Code – Topic:-Fugacity and Fugacity coefficient for pure species and species in solution

Presented By CHINTAN PATEL( ) DHRUV R. PATEL( ) DHRUV V. PATEL( ) HARDIK PATEL( ) HARSH PATEL( )

Index Fugacity and fugacity coefficient :pure species Fugacity coefficients from the generic cubic equation of state Vapour /liquid equilibrium for pure species Fugacity of pure liquid Fugacity and fugacity coefficient: species in solution The fundamental residual-property relation Fugacity coefficient from the virial equation of state

Fugacity and fugacity coefficient :Pure species Chemical potential: provides fundamental criterion for phase equilibria however, the Gibbs energy, hence μ i, is defined in relation to the internal energy and entropy - (absolute values are unknown). Fugacity: The origin of fugacity concept resides in equation given below, valid for pure species I in the ideal-gas state. For a real gas fluid, we write an analogous equation that defines the fugacity of pure species I. …….(1) With units of pressure

Residual Gibbs energy Fugacity coefficient

FUGACITY COEFFICIENTS FROM THE GENERIC CUBIC EQUATION OF STATE Evaluation of fugacity coefficients through cubic equations of state follows directly from combination of following equations G R /RT = Z-1-ln(Z-β)-q×I From above equations we can write ln Ø i = Z i -1 - ln ( Z i – β i ) – q i

Where β i, q i and I i are given by following equations, all written for pure species i. β = b × P /RT q = a(T)/ b × RT I = (1/(σ-ε))× ln (Z+σβ/Z+εβ)

VAPOUR/LIQUID EQUILIBRIUM FOR PURE SPECIES Equation Which defines the fugacity of pure species i, may be written for species I as a saturated vapor and as a saturated liquid at the same temperature.

The fugacity of pure species i as an ideal gas is necessarily equal to its pressure. If we subtract the following equations, Both are written for the same temperature and pressure we get following equation. Where G i -G ig is the residual Gibbs energy.

Thus, Where the dimensionless ratio f i / P has been defined as Another new property, the fugacity coefficient, given by symbol Ø i.

“For a pure species coexisting liquid and vapor phases are in equilibrium when they have the same temperature, pressure, and fugacity.” An alternative formulation is based on corresponding fugacity coefficients.

Where above equation expressing equality of fugacity coefficients of vapor/liquid equilibrium for pure species.

Fugacity of pure liquid

Fugacity And Fugacity Coefficient: Species in Solution

The Fundamental Residual-Property Relation

Fugacity coefficient from the virial equation of state

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