Isothermal measurement and modeling of VLE properties for 2,3,3,3-tetrafluoroprop-1-ene + trifluoromethane + tetrafluoromethane ternary system at temperatures from 253.15 K to 273.15 K
Abstract At present, the difficulty in the research of auto cascade refrigeration system lies in the selection of the mixed refrigerant ratio and the design of system process. Accurate thermodynamic data is the key to solve those problems. In this paper, isothermal vapor liquid equilibrium (VLE) behavior was experimentally studied for the strongly-zeotropic ternary mixture 2,3,3,3-tetrafluoroprop-1-ene (R1234yf) + trifluoromethane (R23) + tetrafluoromethane (R14) at 253.15 K, 263.15 K, and 273.15 K. The pressures and the vapor mass fractions were found to be thermodynamically consistent and were satisfactorily correlated with the NRTL-RK model and the MUNIFAC-SRK model. The average absolute relative deviations of pressure (AARD-p), and the average absolute deviations of vapor phase mass fraction (AAD-y1, AAD-y2 and AAD-y3) are less than 0.25%, 0.0032, 0.0048 and 0.0040 for the MUNIFAC-SRK model, respectively, which are better than those of 0.4%, 0.0138, 0.0198 and 0.0049 for the NRTL-RK model. The results of the MUNIFAC-SRK model showed excellent agreement with the experimental values. The isothermal three-dimensional VLE behavior and the isothermal-isobaric ternary VLE diagrams under 1500 kPa were also established using a flash calculation method.