The (p, ρ,T) behaviour of 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea) measured with a Burnett apparatus

Abstract

A Burnett-type apparatus for the determination of the compression factor and virial coefficients of gases has been constructed and calibrated by helium. The apparatus operates from near room temperature toT=473 K and pressures up to 60 MPa. To evaluate the capability of the apparatus, Burnett expansion series were performed with 1,1,1,2-tetrafluoroethane (HFC-134a) atT=393 K. The new measured data for HFC-227ea at the temperatures 393 K and 423 K and pressures ranging from 0.2 MPa to 50 MPa are presented. A finite density virial expansion was employed to derive compression factors and second virial coefficients from the data obtained. The experimental densities and second virial coefficients are compared with values calculated by the internationally agreed equations of state of helium and HFC-134a. The experimental uncertainty of the measurements is estimated to be ±0.0002<@TBLEND>pin pressure and ±0.005 K in temperature. The uncertainties involved in the measurement of the density and the virial coefficients are discussed.