Measurements of vapor pressure, vapor-liquid coexistence curve and critical parameters of refrigerant 152a

Forty-four vapor pressures of Refrigerant 152 a (CH₃ CHF₂ : 1, 1-difluoroethane) between 273 and 386 K were measured in the range of pressures from 0.26 to 4.48 MPa. Ten saturated liquid densities and eleven saturated vapor densities near the critical point were also measured in the range of temperatures from 370 K to the critical temperature which corresponds to a density variation of 153 to 635 kg·m^-3. The experimental uncertainties of temperature, pressure and density measurements were estimated within ±10 mK, ±0.8 kPa and ±0. 55 %, respectively. On the basis of these results, the critical temperature, critical pressure and critical density of R 152 a were determined to be 386.44 K, 4.5198 MPa and 368 kg·m^-3, respectively, in consideration of the meniscus disappearing level as well as the intensity of the critical opalescence. In addition, the correlation of vapor pressure and that of the vapor-liquid coexistence curve were also proposed.