Experimental speed of sound for cis-1,3,3,3-tetrafluoropropene (R1234ze(Z)) and hexafluoropropene (R1216) in gaseous phase

Abstract

cis-1,3,3,3-Tetrafluoropropene (R1234ze(Z)) and hexafluoropropylene (R1216) are considered the alternative low-global-warming-potential working fluids due to their good performance in high-temperature heat pumps and organic Rankine cycle (ORC) systems. Thermodynamic data with high precision are required for performance analysis and industrial application, among which speed of sound data are essential for designing the system components and deriving other thermodynamic properties. In this work, we measured the speed of sound in the gaseous phase of R1234ze(Z) and R1216 using a fixed-path cylindrical acoustic resonator. The experimental temperature and pressure ranges of R1234ze(Z) are (303.15 to 363.15) K and (129 to 730) kPa, respectively; and those for R1216 are (293.15 to 363.15) K and (130 to 1001) kPa. The ideal-gas heat capacity and the virial coefficients up to 3th order were calculated from the experimental data. The uncertainties of the measured and derived properties are exhaustively analyzed and calculated. The combined expanded relative uncertainties (k=2) of the measured sound of speed are 2.8×10−4 for R1234ze(Z) and 2.4×10−4 for R1216. The combined expanded relative uncertainties (k=2) of the derived ideal-gas heat capacity are 0.018 for R1234ze(Z) and 0.010 for R1216. The combined expanded relative uncertainties (k=2) of the second density virial coefficient are 0.033 for R1234ze(Z) and 0.013 for R1216.