Experimental measurements and molecular simulations for pvTz properties of carbon dioxide (CO2) + 1,1-difluoroethylene (R1132a) binary system in the two-phase and superheated vapor regions

This study provides 23 two-phase and 133 vapor-phase pressure-specific volume-temperature-composition (pvTz) measurements for the mixture containing carbon dioxide (CO2) and 1,1-difluoroethylene (R1132a), considered a potentially low global warming potential (GWP) alternative for ultralow temperature refrigeration systems. Vapor-liquid equilibrium (VLE) and vapor-phase pvTz properties predicted through molecular dynamics (MD) simulations are also presented. An isochoric apparatus was used to measure the properties for ten CO2 mole fractions along ten isochores with specific volumes equal to (0.016846, 0.018521, 0.028775, 0.029922, 0.029931, 0.032358, 0.037241, 0.039089, 0.052176, 0.083492) m3 kg−1 in the temperature and pressure ranges from (228.15 to 303.15) K and from (404.5 to 2519.9) kPa, respectively. The two-phase measurements were used to assess the VLE of the binary system by the flash method with the Peng-Robinson (PR) and PC-SAFT equations of state (EoSs), yielding average absolute relative deviations (AARDs) between experimental and calculated pressures of 0.20% and 0.19%, respectively. The values calculated with the PR and PC-SAFT EoSs showed qualitative agreement with the VLE properties from MD simulations, yielding AARD(p) of 3.44 % and 3.32 %, respectively. The measurements carried out in the superheated vapor region were compared with calculations from the PR and PC-SAFT EoSs, obtaining low deviations (AARD(p) of 0.38 % for the PR EoS and 0.33 % for the PC-SAFT EoS). Finally, a qualitatively good agreement between the MD simulations and the EoS calculations was also observed in the superheated vapor region (AARD(p) of 1.02 % for the PR EoS and 1.00 % for the PC-SAFT EoS).