Pseudo-Pure Fluid Equations of State for the Refrigerant Blends R-410A, R-404A, R-507A, and R-407C
Eric W. Lemmon
Pseudo pure-fluid equations of state explicit in Helmholtz energy have been developed to calculate the thermodynamic properties of the refrigerant blends R-410A, R-404A, R-507A, and R407C. The equations were fitted to calculated values from a mixture model developed in previous work for mixtures of R-32, R-125, R-134a, and $-143a. The equations may be used to calculate the single phase thermodynamic properties of the blends; dew and bubble point properties are calculated with the aid of additional ancillary equations for the saturation pressures. Differences between calculations from the pseudo pure-fluid equations and the full mixture model are on average 0.01%, with all calculations less than 0.1% in density except in the critical region. For the heat capacity and speed of sound, differences are on average 0.1% with maximum differences of 0.5%. The equations are valid from 200 to 450 K and can be extrapolated to higher temperatures.