Burnett measurements and correlation of gas-phase ( P, ρ, T) of 1,1,1,2-tetrafluoroethane (R 134a) and of 1,1-difluoroethane (R 152a)

Abstract

Extensive measurements of (p, ρ, T) in the gas phase of the refrigerants R 134a and R 152a were performed with a Burnett apparatus. For R 134a, a total of 411 points located on 19 isotherms between 293.15 K and 453.15 K were obtained at pressures between 0.1 MPa and 16 MPa. A total of 335 (p, ρ, T) triplets for R 152a were determined in the same pressure range on 17 isotherms between 293.15 K and 433.15 K. Estimated uncertainties of temperature, pressure, and density are 5 mK, 0.0001 · p, and 0.0003 · ρ, respectively. The new (p, ρ, T) results are represented by truncated virial equations of state within their estimated uncertainties for pressures up to 4.5 MPa. Second virial coefficients obtained during reduction of Burnett results show good agreement with second virial coefficients reported by other research groups mostly derived from speed-of-sound measurements.