Vapor — Liquid Equilibrium in Multicomponent Mixtures of Hydrogen’s Isotopes

Abstract

An important issue in the separation of hydrogen's isotopes using cryogenic distillation is the precise knowledge of the vapor-liquid equilibrium. To computes the equilibrium, we considered the non-idealities both in the vapor and in the liquid phase. We computed the specific volumes of hydrogen's isotopes with the aid of the virial equation of state and the Redlich-Kwong equation of state. The enthalpy of evaporation was computed with the aid of the Clausius-Clapeyron equation, where the saturation pressure for hydrogen's isotopes was expressed with the Mittelhauser equation. For the activity coefficients on the liquid phase, we made a comparative study of Hildebrand and Margules theories applied to mixtures of hydrogen's isotopes. The model is in good agreement with experimental data obtained for mixtures: H2-D2 and H2-HD. Relevant data obtained on ternary mixtures are presented (as Gibbs diagrams).