Compressor

Simulate chemical processes using advanced thermodynamic models

Brought to you by: danwbr

Compressor

Forum: Help (Classic UI)

Creator: Juan Ignacio Manassaldi

Created: 2018-03-22

Updated: 2018-04-06

Juan Ignacio Manassaldi - 2018-03-22

Hello, when changing the calculation type in the compressor the results are not the same.
Calculation type: Power requirement (40 kw) oulet pressure 6.91 bar
Calculation type: oulet pressure 6.91 bar Power requirement (36.068 kw)

For the first case, if I calculate manually (the power requeriment) it does not coincide with the specified 40 kw.

Am I wrong?
Bye!

Last edit: Juan Ignacio Manassaldi 2018-03-22

compressor.dwxmz

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Juan Ignacio Manassaldi - 2018-03-23

I looked the manual in more detail and I think it's because of the calculation sequence used by the unit.
Thanks

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ioncube - 2018-03-24

Weird! I am reproducing the same problem. Juan, however, if you look at the popup menu of energy streams for both compressors the power is ~36kW

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Daniel Medeiros - 2018-03-24

The equation used to calculate outlet pressure from power is based on an ideal assumption. I'll fix that on the next release.

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Juan Ignacio Manassaldi - 2018-03-24

Hi Daniel, I discovered it after posting.
When I solve a similar problem manually, the sequence I use is:
- Hout from the power input
- Hisout from efficiency deffinition
- Pou and Tisout from a 2x2 system of equations.
Sisout = f (Tisout, Pout, composition)
Hisout = f (Tisout, Pout, composition)
- Tout from outlet stream enthalpy

Nomenclature
Hout: outlet stream enthalpy
Hisout: isentropic outlet stream enthalpy
Sisout: isentropic outlet stream entropy (equal to the input entropy)
Pout: outlet pressure
Tout: outlet stream temperature
Tisout: isentropic outlet stream temperature

Bye!

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Daniel Medeiros - 2018-03-26

Thanks for the report guys, this will be fixed on the next release.

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Daniel Medeiros - 2018-03-26

https://github.com/DanWBR/dwsim5/commit/700adb4770afba827e5b4a847ca2eff4402a622a#diff-0414981edc96695492651c60799d8a6a

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Juan Ignacio Manassaldi - 2018-04-06

I used Python UO to solve this problem. Its implementation in simple because I am not python user.
Thanks Again!

power_compressor.dwxmz

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