Acoustic Properties and Derived Virial Coefficients for Gaseous Mixtures of 2,3,3,3-Tetrafluoropropene (R1234yf) + Hexafluoropropylene (R1216)

The thermodynamic performance, safety, and environmentally friendly demands of the thermodynamic cycle are driving the exploration of new working fluid mixtures. Mixtures containing the fourth-generation refrigerant 2,3,3,3-tetrafluoropropene (R1234yf) show high application potential in many thermodynamic and refrigeration systems. Herein, we first measured the speed of sound of R1234yf + hexafluoropropylene (R1216) binary mixtures from 298 to 358 K and 45 to 1010 kPa with a relative combined uncertainty (k = 2) of 0.03%. Using the speed of sound data, we determined the compositions with an absolute combined uncertainty (k = 2) of 0.0013 mole fraction and determined the parameters of the hard core square well molecular potential model at the compositions. The interaction virial coefficients were derived experimentally and theoretically and were roughly consistent with each other over a far wider temperature range than the experimental temperatures. The current thermodynamic models were examined using the speed of sound data, and room for improvement was discovered.