Normal volume flow computation

Discusses use of COCO, the process simulation and modelling software suite from AmsterCHEM, downloadable from http://www.cocosimulator.org

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Normal volume flow computation

Postby spertant » 01 March 2024, 13:43

Dear Jasper,

I'm facing issues with the computation of the normal volume flow in my simulation. Indeed, the measured normal volume flow does not give the same value as the normal volume flow that I compute, using the total molar flow and the ideal gas law.
It is especially obvious after a mixer, as you can see in the attached file.
How can this be explained ?

Thanks for your help.

Best Regards,
Savinien
Attachments
TEST_FLOWRATE_NM3H.fsd
TEST NORMAL VOLUME FLOW COMPUTATION
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spertant
 
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Re: Normal volume flow computation

Postby jasper » 01 March 2024, 14:37

Before the mixer: the values match to the 4th digit (corresponding with the accuracy of the gas constant you put in the information calculator) if you switch the vapor phase thermo to Ideal Gas. But in the document as attached, the vapor phase is set to Peng Robinson.

After the mixer: If you bring stream 4 to 101325 Pa and 273.15 (the normal conditions selected in the measure unit), you will see that there is 4.5% liquid under these conditions, which causes the much larger mismatch with the ideal vapor calculation.
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Re: Normal volume flow computation

Postby spertant » 05 March 2024, 12:20

Ok, I thought that the normal volume flow was always computed using the Ideal Gas law, regardless of the selected equation of state.
Thanks
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Re: Normal volume flow computation

Postby jasper » 05 March 2024, 14:06

The MeasureUnit help explains what the MeasureUnit does: https://www.cocosimulator.org/index_hel ... reunit.htm

I do not think there is one single definition that fits all purposes. If you need the ideal gas volume, I suggest you use the approach you sketched with the information calculator.
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