Speed of Sound Measurements of Binary Mixtures of -1,2-Difluoroethylene (R-1132(E)) with Difluoromethane (R-32) or 2,3,3,3-Tetrafluoropropene (R-1234yf).

The speed of sound of two binary mixtures containing 0.336 mole fraction -1,2-difluoroethylene (R-1132(E)) with difluoromethane (R-32) and 0.435 mole fraction R-1132(E) with 2,3,3,3-tetrafluoropropene (R-1234yf) was measured with a dual-path pulse-echo instrument. The speed of sound was measured along several pseudoisochores for each blend at temperatures ranging from 230 to 325 K for blends with R-32 and to 342 K for blends with R-1234yf. Measurements started at pressures just above each mixture's bubble point pressure and were limited to 8 MPa to avoid potential disproportionation reactions of R-1132(E). The data were compared to multifluid models incorporating Helmholtz-energy-explicit equations of state (EOS) for each pure fluid. No binary interaction parameters for either the R-1132(E)/32 or R-1132(E)/1234yf system are currently available. Therefore, binary interaction parameters for chemically similar systems suggested by REFPROP version 10.0 were used. Deviations from the measured data to the EOS ranged from 5.5 to 11.0% for the R-1132(E)/32 system and from 0.4 to 1.8% for the R-1132(E)/1234yf system. These data will be used to refit the R-1132(E) EOS and fit mixture models for R-1132(E) blends with R-32 and R-1234yf.