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# Enthalpy Of The Exit Stream Corresponding To The Inlet Entropy

compressor calculations hysys

3 replies to this topic
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### #1 rahza.izak

rahza.izak

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Posted 22 September 2022 - 11:03 AM

Hi,

I am trying to learn calculations for Compressor efficiency and my college has Hysys available, I am going through its operations Guide and i am able to reasonable understand and do the calculations in excel for the most part. I am stuck at Isentropic path where I need to calculate either the enthalpy or density of the exit stream corresponding to the inlet entropy. Can some one please explain or show an equation that can be used to do this.

1. For example to calculate Isentropic power, the volume exponent has log to base e of density of the exit stream corresponding to the inlet entropy divided by density of inlet stream. how do I calculate the density of the exit stream corresponding to the inlet entropy.

2. Similarly, for the correction factor there is enthalpy of the exit stream corresponding to the inlet entropy, please help me to calculate this, I cannot understand/find any equation to do this.

Thanks

### #2 PaoloPemi

PaoloPemi

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Posted 23 September 2022 - 04:15 AM

there are several methods available for solving a polytropic stage, see for example ASME PTC-10 (based on Schultz formulations), Huntington (based on  integration of Hi =  Viavg*Dpi) etc.

With Excel, OpenOffice and Python I utilize a different software (Prode Properties)  which allows to solve the complete set of flash operations (in addition to include methods for polytropic stages) , by writing a simple iterative procedure one can solve the polytropic stage, the results are about the same of the specific methods included in the software

### #3 breizh

breizh

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Posted 23 September 2022 - 05:01 AM

Hi,

To support your work following Paolo's recommendation , let you study the doc attached .

Breizh

### #4 rahza.izak

rahza.izak

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Posted 17 October 2022 - 09:36 AM

Thanks, I am going through PTC-10 and it seems to have the answer, will take a while for me to get that done. Thanks again for pointing me in the right direction.