1 reply to this topic

[Kakka]

Hi everyone,

I recently got an opportunity to work as a condition monitoring engineer and have been studying compressor performance as part of my role. It's been an exciting journey, but each time I dive deeper into the subject, I find myself with new questions that aren’t easily answered online.

Thanks to this platform, I can reach out to experienced professionals for guidance.

 

Here’s one of my current doubts:
Does the polytropic head change with the density of the gas? From the equation, I understand that it is proportional to the pressure ratio and inversely proportional to the molecular weight. This pressure ratio itself is influenced by the mass flow rate or density ratio.

Based on this understanding, I’ve been thinking that as the mass flow rate increases, the polytropic head should reduce for the same energy supply. Additionally, I suspect that a compressor's characteristic curve (head vs. flow) for a specific gas density might not hold true if the gas density changes.

Could someone kindly confirm if this reasoning is correct or point out where I might be going wrong?

Looking forward to your insights!

 

Best regards,
Nidhin 

[PingPong]

From the equation, I understand that it is proportional to the pressure ratio and inversely proportional to the molecular weight.

 

No, it is the other way around.

A centrifugal compressor delivers a Head. The resulting pressure ratio is a function of that Head as well as the temperature and physical properties of the gas.
 

 

Note what I wrote earlier in this topic:

https://www.cheresou...olytropic-head/

 

Note also the documents that breizh posted there, as well as in this topic:

https://www.cheresou...al-compressors/