Coexistence curve of HFC-134a and thermal conductivity of HFC-245fa

The present paper deals with the experimental results for the refractive in dex of the saturated vapor and liquid of HFC-134a and the thermal conductiv ity of HFC-245fa in the liquid phase. The coexistence curve of the refractive index of HFC-134a up to the critica l temperature has been measured. The density coexistence curve of HFC-134a in the critical region is calculated from the refractive index data by usin g the Lorentz-Lorenz equation. Assuming as the critical density rho (C) = 5 11.0 kg m(-3), the critical temperature T-C = 374.107 +/- 0.020 K and the c ritical index beta = 0.348 +/- 0.001 are obtained. The calculated density c oexistence curve proved to be reasonable from the agreement with the direct ly measured values of density and the equation of state recently reported. The thermal conductivity of HFC-245fa in the liquid phase has been measured by using a transient hot-wire method. The nominal diameter of the long and short wires is 20 mum and the effective length of them is around 60 mm. Me asurements are carried out in the range from 253 to 315 K and up to 15 MPa. The results for the thermal conductivity are correlated by the equation of temperature and pressure. The present results of KFC-245fa are compared wi th the predicted values of HFC-245fa as well as the experimental values of some propane series refrigerants. (C) 2000 Elsevier Science B.V. All rights reserved.