Dielectric Constant of the Nearly Azeotropic Mixture R410A1

The purpose of this paper is to present dielectric constant measurements of R410A, a chlorine-free refrigerant, which is a 50/50 (mass %) mixture of R32/125. The measurements on R410A were performed as a function of pressure and temperature ranging from 2 to 16 MPa and from 217 to 304 K, respectively, by using a direct capacitance method. The values of dielectric constant have an estimated repeatability of ±0.01% and an accuracy of ±0.1%. The data were correlated as a function of density and pressure. The theory developed by Vedam et al., and adapted by Diguet, and the Kirkwood modification of the Onsager equation for the variation of the modified molar polarization with temperature and density were applied to analyze the data and to obtain the dipole moment of R410A in the liquid state. This was found to be 3.31 Debye.