This varies from about 0.62 to about 0.83, depending on the application.
Because of the thermodynamic properties of gases,
a compressor’s overall adiabatic efficiency does not completely indicate its individual stage performance.
The same compressor produces different adiabatic results with different refrigerants and with the same refrigerant at different suction conditions.
In spite of its shortcomings, isentropic analysis has a definite
advantage in that adiabatic work can be read directly from thermodynamic
tables and charts similar to those presented in Chapter 30 of the 2009 ASHRAE Handbook—Fundamentals.
Where these are unavailable for the particular gas or gas mixture, they can be a accuratelycal culated and plotted using thermodynamic relationships.