AN EXPERIMENTAL-STUDY OF THE THERMODYNAMIC PROPERTIES OF 1, 1-DIFLUOROETHANE

Experimental vapor pressures and P - rho - T data of an important alternative refrigerant, 1, 1-difluoroethane (HFC-152a), have been measured by means of a constant-volume method coupled with expansion procedures. Sixty P - rho - T data were measured along eight isochores in a range of temperatures T from 330 to 440 K, at pressures P from 1.6 to 9.3 MPa, and at densities rho from 51 to 811 kg . m-3. Forty-six vapor pressures were also measured at temperatures from 320 K to the critical temperature. The uncertainties of the temperature and pressure measurements are within +/- 7 mK and +/- 2 kPa, respectively, while the uncertainty of the density values is within +/- 0.1%. The purity of the sample used is 99.9 wt%. On the basis of the measurements along each isochore, five saturation points were determined and the critical pressure was determined by correlating the vapor-pressure measurements. The second and third virial coefficients for temperatures from 360 to 440 K have also been determined.