Thermodynamic Property Measurements of Binary Refrigerant Blends HFO1123 + R290

PVTx properties of 0.80 mass fraction HFO1123 + 0.20 mass fraction R290 and 0.65 mass fraction HFO1123 + 0.35 mass fraction R290 refrigerant blends were measured in the temperature range from 300 K to 400 K and at pressures up to 6.9 MPa by the isochoric method along 6 isochores for each blend including the vapor and liquid phases. The expanded uncertainties in temperature and pressure are estimated to be 5 mK and 1.0 kPa (k = 2). The relative expanded uncertainties in density and mass fraction are estimated to be 0.15% and 0.0005 (k = 2), respectively. Saturated densities of these blends were directly measured in the temperature range between 319 K and 342 K by the visual observation of the meniscus disappearance, and also determined from the inflection points of the PVTx isochore-lines. Finally, the critical points of the blends were determined by the consideration of the meniscus disappearing level as well as the intensity of the critical opalescence as T_c = 334.91 ± 0.01 K, ρ_c = 402 ± 3 kg·m⁻³ and P_c = 4392 ± 3 kPa for 0.80 mass fraction HFO1123 + 0.20 mass fraction R290, and T_c = 340.94 ± 0.02 K, ρ_c = 357 ± 3 kg·m⁻³ and P_c = 4429 ± 5 kPa for 0.65 mass fraction HFO1123 + 0.35 mass fraction R290. A Helmholtz energy equation of state (EOS) was compared with the experimental data, and is in good agreement with the obtained PVTx property data with an absolute average deviation (AAD) of 1.1% for 0.80 mass fraction HFO1123 + 0.20 mass fraction R290, and that of 0.7% for 0.65 mass fraction HFO1123 + 0.35 mass fraction R290 in density. In addition, vapor-liquid equilibrium data of HFO1123 + R290 blends were obtained from 263 K to 323 K based on the recirculation method. A mixing parameter of a simple cubic EOS was determined, and the EOS represents the VLE data with an AAD of 0.73% in pressure and 0.010 mol·mol⁻¹ in mole fraction.