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Performance curve

A

AhmadAPC

Mechanical
Joined
May 30, 2025
Messages
2
A liquid ring compressor is available with its performance curves. As we know, the performance test of the compressor is done with air fluid. Now we want to use this compressor for ethylene gas. In this case, how can we use the performance curve to determine the power consumption of the compressor and the electric motor?
Thank you for your guidance.
 
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Hi,
Don't duplicate posts.
Attached documents to support your query.
Edit: a liquid ring vacuum compressor is a displacement compressor, not a centrifugal compressor.
Good luck.
Pierre
 

Attachments

Last edited:
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The given document is for centrifugal compressors.

For positive displacement compressors, a more accurate equation is
1748667221257.png

n_v=gamma=C_p/C_v
R= specific gas constant
m=mass flow rate
T_1=inlet temp, K
Between air and ethylene, the parameters R, n_v, and Z will change. The performance curves need to be modified to take care of the above. Similarly, discharge pressures need to be changed if size and speed are given.

Reference: Compressor Handbook by Paul C. Hanlon
 
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Hi,
Pay attention to the units. The relation above did not state it clearly.
For SI system consider the relation underneath.
k=cp/cv
Qm: mass flow kg/s
T1: inlet temperature K
Pierre




1748829679290.png
 
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