Compressors are machines used to increase the pressure of the working fluid. There are several types
of compressors. The most important types of rotating compressors are radial-flow, axial-flow and
positive displacement.
The compression process (1-2) is irreversible but approximately adiabatic. The work input to the
compressor is:
Win = m (h2 - h1)
Where m= mass flow of air
h2=Enthalpy at outlet
h1=Enthalpy at inlet
The pressure ratio of a compressor is defined as:
r=Po/Pi
where Po=Absolute pressure at outlet Pi=Absolute pressure at inlet
= (h2s-h1)/(h2-h1)