Application of a nonazeotropic mixture to a refrigeration machine offers a new degree of freedom in controlling machine performance by control of circulating mixture composition. Presenting possible thermodynamic cycles of such a machine operating with different mixture compositions requires developing appropriate thermodynamic charts with refrigerant mixture composition as a variable.

This paper presents thermodynamic charts developed for a nonazeotropic mixture, R13B1/R152a. The developed charts (pressure-enthalpy, temperature-entropy, and enthalpy-composition), though for sake of clarity showing limited data, offer important insight for understanding vapor compression cycles for different compositions. An equation of state capable of describing both the liquid and vapor phases, property algorithms and iteration schemes used in determination of the nonazeotropic mixture thermodynamic properties have been explained.