R438A
R438A is a zeotropic mixture consisting of 8.5 weight% R32, 45 % R125, 44.2% R134a, 1.7% Butane and 0.6% Isopentane. It is also known as Freon M099. According to the manufacturer, it is a replacement for R-22 in direct expansion (DX) air conditioning and refrigeration systems. R438A has a molar mass of 99.1 kg/kmol.
Thermodynamic data are provided using a pseudo-pure fluid model in the manner described by:
E. Lemmon
"Pseudo-Pure Fluid Equations of State for the Refrigerant Blends R-410A, R-404A,R-507A, and R-407C"
International Journal of Thermophysics, Vol. 24, No. 4, July 2003
The generalized equation of state was fit by F-Chart Software using thermodynamic property data provided by the manufacturer and the REFPROP 10 program. The reference state for enthalpy and entropy is the IIR recommendation in which the specific enthalpy and entropy of saturated liquid are 200 kJ/kg and 1.0 kJ/kg-K, respectively. The model is applicable for temperatures between 160 K and 460 K with pressures up to 20 MPa.
Transport properties are estimated using data from REFPROP 10.