Thermodynamics of 3-Phase Equilibrium in Argon Based on a Perfect Solid and a Perfect Liquid (v2)

Abstract

Three-phase equilibrium in argon was obtained based on the thermodynamics of a perfect solid and a perfect liquid (v2). The equation of state (EOS) for a perfect solid was obtained from our previous study of a pure substance using spherical molecules. The EOS for a perfect liquid is a van der Waals EOS with the Carnahan-Starling repulsion term to explain 3-phase equilibrium. The Lennard-Jones parameters for argon are applied to these EOSs. The pressure-volume-temperature relations on the equilibrium lines are comparable with experimental and molecular simulation results. The thermodynamic properties under low pressures have reasonable temperature dependences.