Vapor–Liquid Equilibrium Property Measurements and Helmholtz Energy Mixture Models for R1123/CO2 and R1123/R1234ze(E) Binary Mixtures

Abstract Binary mixtures of R1123/CO2 and R1123/R1234ze(E) will be used as next-generation environmentally friendly refrigerants, new measurements and development of mixture models are required. This study measured vapor–liquid equilibrium properties for these two binary mixtures with high accuracy. The measured values were obtained with a recirculation-type apparatus, which consists of a sample equilibrium system, an evaporative expansion system, and a gas chromatograph. Measured vapor–liquid equilibrium properties were obtained in the temperature range from 288 to 328 K for these binary mixtures. The expanded uncertainties (k = 2) are 0.03 K for temperature and 0.28 to 1.1 kPa for 0.6 to 5.3 MPa for pressure. Uncertainties in composition are 0.78 mol % for R1123/CO2 mixtures and 0.47 mol % for R1123/R1234ze(E) mixtures. The measured values were used to obtain the parameters for the Helmholtz energy mixture models. We successfully developed models that accurately reproduce measured boiling-point pressures within approximately ±3% across all temperature and pressure ranges where measured data are available. Extrapolation to states beyond the measurements shows good thermodynamic behavior and the models can be used with confidence.