rQuestionEngineering
Mechanical
Why API 617 compressors use Polytropic efficiency as a performance parameter ?
What is it not Isentropic ?
What is it not Isentropic ?
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Why API 617 compressors use Polytropic efficiency as a performance parameter ?
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Because p1 V1^n = p2 V2^n
A black swan to a turkey is a white swan to the butcher ... and to Boeing.
A black swan to a turkey is a white swan to the butcher ... and to Boeing.
georgeverghese
Chemical
Good question.
Believe that poly E is used in compressors for a given gas composition, since this value remains (more or less) constant for this gas for a given flow and speed, even though pressure ratio across the multistage compressor may change for various operating cases. While isentropic E changes for a given flow and speed as pressure ratio changes.
Isentropic E is only used in gas expansion turbines. There is some explanation given for this in Perry Chem Engg Handbook, but I've yet to understand it.
Believe that poly E is used in compressors for a given gas composition, since this value remains (more or less) constant for this gas for a given flow and speed, even though pressure ratio across the multistage compressor may change for various operating cases. While isentropic E changes for a given flow and speed as pressure ratio changes.
Isentropic E is only used in gas expansion turbines. There is some explanation given for this in Perry Chem Engg Handbook, but I've yet to understand it.
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