High-Pressure Vapor-Liquid Equilibrium Data for a Binary Mixture: the Poynting Factor Correction

pressure in kPa

303.975

option

isobaric VLE diagram

Consider a binary mixture composed of

n

-hexane and

n

-heptane. This Demonstration computes and plots the isobaric vapor-liquid equilibrium diagram, the equilibrium curve, the relative volatility, the

K

-value, the gas-phase fugacity coefficients using the Soave–Redlich–Kwong equation of state (EOS), and the Poynting correction factor for user-specified values of the pressure. The Demonstration takes into account deviation from ideal behavior in the gas phase by including gas phase fugacity coefficients. Thus high-pressure VLE data can be obtained. This Demonstration allows for the Poynting factor correction. Snapshots present calculations at a pressure approximately equal to 303.975 kPa.

VLE data is computed using the following formula (the gamma-phi-poy equation):

ϕ

i

y

i

P=

g

i

x

i

sat

P

i

exp

L

v

i

P-

sat

P

i



RT

, where

y

i

and

x

i

are the vapor and liquid mole fractions of component

i

,

P

is the total pressure,

sat

P

i

is the saturation vapor pressure of component

i

,

ϕ

i

is the vapor-phase fugacity coefficient, and

g

i

is the liquid-phase activity coefficient, where

ϕ

i

and

g

i

are determined using the Soave–Redlich–Kwong equation of state and the Wilson model, respectively;

L

v

i

is the liquid molar volume of molecule

i

determined using the Rackett equation.