Editing Compressor (section)

===Isentropic compressor===
A compressor can be idealized as internally reversible and [[adiabatic]], thus an [[isentropic]] steady state device, meaning the change in [[entropy]] is 0.<ref name="Cengel, Yunus A. 2012">Cengel, Yunus A., and Michaeul A. Boles. Thermodynamics: An Engineering Approach. 7th Edition ed. New York: Mcgraw-Hill, 2012. Print.</ref> 

The enthalpy change for a flow process can be calculated.<ref>{{cite web |last1=Alvi |title=TdS Equations |url=https://web1.eng.famu.fsu.edu/~alvi/EML3015/Lecture-notes/lecture%20notes/entropy%20change/tsld004.htm |website=Florida State University |publisher=Famu |access-date=1 February 2023}}</ref>

dH = VdP +TdS

Isentropic dS is zero.

dH = VdP

Non flow isentropic processes like some positive displacement compressors may use a different equation.<ref>{{cite web |last1=Mae |title=Non-Flow Thermodynamic Processes |url=http://wwwcourses.sens.buffalo.edu/mae431/ES12Ch04.pdf |website=courses.sens |publisher=buffalo.edu |access-date=2 February 2023}}</ref>

dH = PdV 

By defining the compression cycle as [[isentropic]], an ideal efficiency for the process can be attained, and the ideal compressor performance can be compared to the actual performance of the machine. Isotropic Compression as used in [[ASME]] PTC 10 Code refers to a reversible, adiabatic compression process<ref name="PTC 10 - Compressors and Exhauters">{{Cite web|url=https://www.asme.org/codes-standards/find-codes-standards/ptc-10-performance-test-code-compressors-exhausters|archive-url=https://web.archive.org/web/20150619013643/https://www.asme.org/products/codes-standards/ptc-10-1997-performance-test-code-compressors|url-status=dead|title=PTC-10 Performance Test Code on Compressors & Exhausters - ASME|archive-date=June 19, 2015|website=www.asme.org}}</ref>

Isentropic efficiency of Compressors:
: <math> \eta _C = \frac{\rm Isentropic \;Compressor\;Work}{\rm Actual\;Compressor\; Work}=\frac{W_s}{W_a} \cong \frac{h_{2s}-h_1}{h_{2a}-h_1}  </math>

: <math> h_1 </math> is the [[enthalpy]] at the initial state
: <math> h_{2a}</math> is the [[enthalpy]] at the final state for the actual process
: <math> h_{2s}</math> is the [[enthalpy]] at the final state for the isentropic process