Relative permittivity of liquid HFC-236ea and HFC-245fa at temperatures from 293 to 343 K and pressures up to 50 MPa

The static relative permittivity (dielectric constant) of 1,1,1,2,3,3-hexafluoropropane (HFC-236ea) and 1,1,1,3,3-pentafluoropropane (HFC-245fa) in the liquid phase has been measured by a concentric cylinder-type high pressure capacitor with an LCR-meter at temperatures from 293 to 343 K and pressures up to 50 MPa. The uncertainty of the measurements is estimated to be within 1%. The relative permittivity of liquid HFC-236ea and HFC-245fa increases with increasing pressure and decreases with increasing temperature. The data obtained along an isotherm were correlated with pressure using the Owen–Brinkley equation within the experimental uncertainty. Density dependence of the relative permittivity was also investigated. Based on the experimental data the apparent dipole moment of liquid HFC-236ea and HFC-245fa were determined with the Kirkwood theory.