AN EXPERIMENTAL-STUDY OF THE THERMODYNAMIC PROPERTIES OF THE REFRIGERANT MIXTURE - (1,1,1,2-TETRAFLUOROETHANE (R 134A)+1,1-DIFLUOROETHANE (R 152A))

The thermodynamic properties of (1,1,1,2-tetrafluoroethane (R 134a) + 1,1-difluoroethane (R 152a)) have been measured in an extended range of pressure p and temperature T. 959 (p, ρ, T, x) values were obtained with a vibrating-tube apparatus between T = 243.27 K and 413.15 K and p up to 16 MPa. 718 values were measured with a Burnett apparatus between T = 293.15 K and 433.15 K for p up to 16 MPa. The (vapour + liquid) equilibrium has been investigated for 23 temperatures and compositions between T = 303.15 K and 378.15 K. By extrapolation of measured liquid densities on subcritical isotherms, 42 saturated-liquid densities were derived. All measurements were performed for mixtures with 0.25, 0.50, and 0.75 mole fraction of R 134a. The measurements in the single-phase region were used to establish equations of state for the liquid and for the superheated vapour. Both equations represent the input values within 0.0005·ρ. The (vapour + liquid) equilibrium has been described by a modified Redlich-Kwong equation. Mixing effects are generally small. In the single-phase region, the volume of mixing rarely exceeds 3 per cent and can be neglected for most technical applications. The (vapour + liquid) equilibrium shows a slightly negative deviation from Raoult's law. © 1993 Academic Press. All rights reserved.