Equilibrium Measurements by the Vapor-Liquid Flow Method

A method for the measurement of vapor-liquid equilibrium is described which is based on a dynamic flow type "vapor-liquid flow method". The method consists of passing a gaseous mixture under steady state conditions through an equilibrium cell where partial condensation occurs. An equilibrium state is obtained between the liquified porition and remaining gas and these two phases are removed continuously to gas sampling ports.Vapor-liquid equilibrium data are reproted for n-butane-isobutane, n-butane-vinyl chloride, and n-butane-carbon dioxide systems at isothermal condition of 0°C. These data were used to compare with ideal behaviors and the authors' previous results taken at higher temperature and pressure conditions.From experimental results for n-butane-isobutane which is believed to form an ideal solution, negative deviation from ideality was shown and the activity coefficients for lighter component (isobutane) was shown to be less than unity and no cross-point in activity coefficient was found for the system.Finally, experimental data for n-butane-isobutane and n-butane-vinyl chloride were tabulated in smoothed forms which were obtained using a smoothing method proposed by the authors which was based on a simple relation in equilibrium ratio of the constituents.