Modeling approach for the high pressure solid-fluid equilibrium of asymmetric systems

S.B. RODRIGUEZ REARTES ; M. CISMONDI; M.S. ZABALOY

INDUSTRIAL & ENGINEERING CHEMICAL RESEARCH

AMER CHEMICAL SOC

Lugar: Washington, DC; Año: 2011 vol. 50 p. 3049 - 3059

0888-5885

In this work, we evaluate the potential of a modeling approach for describing the solid-fluid equilibria of highly asymmetric mixtures over a wide pressure range. The model uses a mathematical expression for the fugacity of a pure heavy compound in solid state for which the reference state is the saturated solid under conditions of solid-liquid (melting) equilibrium at the system temperature T. Such reference state differs from a common choice which corresponds to the pure solid under conditions of solid-vapor (sublimation) equilibrium at T. By construction, the present modeling approach matches the solid-liquid equilibria at high concentration of the heavy component. We discuss and test here a parameterization strategy for avoiding the simultaneous correlation of fluid-fluid and solid-fluid experimental data: first the fluid-fluid equilibrium experimental data are correlated in the conventional way, and, next, the solid-fluid equilibrium data are correlated by fitting a parameter that has no influence on the equation of state that describes the fluid phases. In this work, we study in detail the highly asymmetric system methane + n-triacontane, for which experimental data are available over a wide range of conditions1. To model this system we use a specific form of the present modeling approach. Such specific model gives a good quantitative performance even at pressures in the order of 2000 bar. Besides, we present additional modeling results for two other systems, i.e., for methane + n-eicosane and methane + n-tetracosane, which are also highly asymmetric.