Relative Permittivity and Resistivity of Liquid HFC Refrigerants Under High Pressure

The static relative permittivity (dielectric constant) and the resistivity of HFC- 236ea (CF3-CHF-CHF2) and HFC-245fa (CF3-CH2-CHF2) in the liquid phase were studied at temperatures from 293 to 343 K and pressures from 0.1 to 50 MPa. The relative permittivity was measured by a concentric-cylindertype capacitance cell with an LCR meter with an uncertainty of less than 0.1 %. The resistivity was measured by a high resistance meter using plane-parallel platinum electrodes installed in a borosilicate glass syringe. It was found that the relative permittivities and the resistivities of liquid HFC-236ea and HFC- 245fa at 303 K and 0.101325 MPa are about 5.13 and 6.54 and 1.5 x 1010 and 0.2 x 1010 O.cm, respectively. The relative permittivity and the resistivity increase monotonically with increasing pressure and decreasing temperature.