Compressor power equations

Asalamoalekum,

i am doing calculation for compressor power requirement, though its an vendor item but as an assignment form my boss i need to find equations for calculation of compressor power.:cupcake:

I used thermodynamic equation of polytropic head to find compressor power, but he is insisting that there are 2 more equation to calculate power of compressor.:suspicion:

Searching every where to get those equation but i am unable to find it from process side.

help me out

thankx in advance...