Vapor-Phase (p,ρ,T) Behavior of Difluoromethane (R32) + Trifluoroiodomethane (R13I1), Pentafluoroethane (R125) + R13I1, and R32 + R125 + R13I1 Mixtures: Experimental Measurements Based on the Isochoric Method and Verification with a Generalized Virial Equation of State

Mixing R13I1 with flammable or weakly flammable refrigerants is an approach to reduce both their flammability and global warming potential (GWP); however, thermodynamic property data of mixtures containing R13I1 are currently scarce. In this work, experimental measurements were performed for the (p, ρ, T) behavior in the vapor-phase of R32 + R13I1, R125 + R13I1, and R32 + R125 + R13I1 mixtures. The measurements were made at temperatures from 300 K to 400 K and pressures up to 6.3 MPa, and 44 data points were obtained for the R32 + R13I1 mixture and 25 data points for the R125 + R13I1 mixture. For the ternary mixture, 25 data points were obtained at the composition of R466A (R32:R125:R13I1 = 49:11.5:39.5 mass %). The validity of the experimental data was verified by comparing to the virial equation of state generalized for nonpolar or weakly polar fluids based on the corresponding states principle. The comparison showed that deviations between the experimental and calculated pressures are generally minor and less scattered; this suggests that the (p, ρ, T) data obtained in this work are reasonable in terms of the law of corresponding states.