Investigation on Solid–Liquid Equilibrium for Nitrogen + Argon and Nitrogen + Tetrafluoromethane Binary Systems

Abstract

The solid–liquid equilibrium (SLE) at cryogenic temperature is crucial foundational information in various fields, including mixed-refrigerant refrigeration technology, high-temperature superconductors, and aerospace propellants. In this study, SLE data for binary mixtures of nitrogen (N₂) + argon (Ar) and nitrogen (N₂) + tetrafluoromethane (CF₄) were experimentally measured over the full composition range. The experimental measurements were conducted using a combined visual and thermal analysis method. The temperature range for the N₂ + Ar system was from 62.75 to 76.78 K, while the N₂ + CF₄ system data were obtained in the temperature range from 61.78 to 86.76 K, showing eutectic behavior. Several thermodynamic models were applied to correlate the data, among which the NRTL model demonstrated the best correlation, with an average absolute relative deviation (AARD_T) of 1.40%.