Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

This paper provides reliable dielectric property information on two refrigerant mixtures regarded as replacements for chorodifluoromethane (CAS no. 75-45-6) (HCFC22) and R502 (CHClF2 + CClF2CF3) (w1 ) 0.49; w2 ) 0.51). Liquid phase relative permittivity measurements are reported for R408A (CHF2CF3 + CF3CH3 + CHClF2) (w1) 0.07; w2) 0.46; w3) 0.47) and R409A (CHClF2 + CHClFCH3 + CClF2CH3) (w1 ) 0.60; w2 ) 0.25; w3 ) 0.15). The measurements were performed by using a direct capacitance method at temperatures from T ) (233 to 303) K under pressures up to 16 MPa. A complete set of tables of experimental data, covering dielectric property needs for most engineering applications, is provided. The data obtained was correlated as a function of density, pressure, and temperature. The apparent dipole moments (i/) of R408A and R409A in the liquid state were obtained from the Kirkwood modification of the Onsager equation for the variation to the modified molar polarization with temperature and density. The i/ value found for R408A was 1.043 * 10-29 C*m and 1.047 * 10-29 C*m for R409A. The coefficient of thermal expansion and the coefficient of compressibility in the liquid state were derived from the experimental data, with uncertainties better than 2 % and 0.3 %, respectively.