Transport properties of refrigerants R32, R125, R134a, and R125+R32 mixtures in and beyond the critical region

A practical representation for the transport coefficients of pure refrigera nts R32, R125, R134a, and R125 + R32 mixtures is presented which is valid i n the vapor-liquid critical region. The crossover expressions for the trans port coefficients incorporate scaling laws near the critical point and are transformed to regular background values far away from the critical point. The regular background parts of the transport coefficients of pure refriger ants are obtained from independently fitting pure fluid data. For the calcu lation of the background contributions of the transport coefficients in bin ary mixtures, corresponding-states correlations are used. The transport pro perty model is compared with thermal conductivity and thermal diffusivity d ata for pure refrigerants, and with thermal conductivity data for R125 + R3 2 mixtures. The average relative deviations between the calculated values o f the thermal conductivity and experimental data are less than 4-5% at dens ities rho greater than or equal to 0.1 rho(c) and temperatures up to T = 2T (c). (C) 1999 Elsevier Science Ltd and IIR. All rights reserved.