DIELECTRIC-CONSTANT AND DIPOLE-MOMENTS OF 1,1,1-TRIFLUORO-2,2-DICHLOROETHANE (HCFC-123) AND 1,1-DIFLUOROETHANE (HFC 152A) IN THE LIQUID-PHASE

Experimental data of the dielectric constant of HCFC 123 and HFC 152a as a function of pressure and temperature in the temperature range fro m 200 to 300 K and pressures up to 18 MPa were correlated as a functio n of pressure and temperature, with an uncertainty of +/-0.01 for HCFC 123 and +/-0.12 for the HFC 152a, and as a function of density and te mperature with an uncertainty of +/- 0.005 for HCFC 123 and +/-0.034 f or HFC 152a. The uncertainty of the results obtained for the dielectri c constant was estimated at a 95% confidence level to be +/-7.27 x 10( -3) for HCFC 123 and +/-3.26 x 10(-2) for HFC 152a. The theory develop ed by Vedam and Chen [K. Vedam, C, Chen, Importance of using eulerian representation of strain in high pressure studies on liquids, J. Chem. Phys., Vol. 77, 1982, pp. 1461-1463] and adapted by Diguet [R. Diguet , Density dependence of refractive index and static dielectric constan t, Physica, 139 and 140B, 1986, pp. 126-130] and the Kirkwood modifica tion of the Onsager equation for the variation of the modified molar p olarization with temperature and density were applied to analyse the d ata and to obtain the dipole moment of both refrigerants in the liquid state. These were found to be 2.13 D for HCFC 123 and 3.69 D for HFC 152a. (C) 1998 Elsevier Science B.V. All rights reserved.