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

Consider a binary mixture composed of -hexane and -heptane. This Demonstration computes and plots the isobaric vapor-liquid equilibrium diagram, the equilibrium curve, the relative volatility, the -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):

, where and are the vapor and liquid mole fractions of component , is the total pressure, is the saturation vapor pressure of component , is the vapor-phase fugacity coefficient, and is the liquid-phase activity coefficient, where and are determined using the Soave–Redlich–Kwong equation of state and the Wilson model, respectively; is the liquid molar volume of molecule determined using the Rackett equation.