What factors affect the efficiency of compressors?

[chhitiz]

given the same volume and rate of air flow, which would be more efficient compressor between a rotary vane compressor and a bellow?

 

[Q_Goest]

Hi chhitz. What do you mean by a bellow compressor? I've heard of compressors that use edge welded bellows as the sealing and compressing mechanism, is that what you're referring to?

Regardless of what kind of compressor you refer to, let me also ask you, what do you think the various factors are that reduce isentropic efficiency? Note that a reduction in isentropic efficiency generally implies an increase in power required over and above that for a perfectly isentropic compression.

Alternatively, we might recognize that some compression processes are closer to isothermal, in which case, what do you think happens to the power required to compress a given gas a given dP and a given mass flow rate as you approach the isothermal case?