Dynamic setting Flash drum TOP oultet stream MoleFlow

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

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ioncube
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Joined: 30 December 2017, 20:13

Dynamic setting Flash drum TOP oultet stream MoleFlow

Post by ioncube »

I am attaching a screenshot & a case file for twin staged refrigeration cycle. I cannot resolve my issue ...which is detailed below:
The ChemsepFlash_UO is fed with a stream containing vapour as well as liquid phase where vapour phase is to be completely separated. Now if I know vapour fraction & flow in my feed stream how can I modify my case such as the TOP outlet flow from ChemsepFlash_UO is auto-adjusted ...& I don't have to manually input it using ChemSep GUI (added screenshot)
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PROPANE_REFRIGERATION_LOOP_CHALLENGE_bug.fsd
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_bug.png
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jasper
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Re: Dynamic setting Flash drum TOP oultet stream MoleFlow

Post by jasper »

1) double click the column, hit in the chemsep GUI, hit Edit. Select CAPE-OPEN in the tree. Click Show All Options. In variables, add (input) Flash Vapour Flow. Save and close.
2) on the Port page, Port Operations, Add Virtual information port, Input, Flash Vapour Flow
3) hook the new port up to a controller
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ioncube
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Re: Dynamic setting Flash drum TOP oultet stream MoleFlow

Post by ioncube »

Jasper ...I cannot find thanks button inn this forum :D
Attached is the corrected sheet.
My other query is ...what is SCALE parameter in Controller? I cannot find comprehensive literature on it. What if I want convergence to be NOT so accurate ...say an accuracy of 0.01 is acceptable how do I do that?
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PROPANE_REFRIGERATION_LOOP_CHALLENGE_bug_fixed.fsd
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jasper
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Re: Dynamic setting Flash drum TOP oultet stream MoleFlow

Post by jasper »

Glad it worked out.

Setting the scale to 1e-3 causes a relative error on the measurement to be relative w.r.t. 1/1e-3. So if your rel. tolerance is set to the default of 1e-5, an error of 0.01 would pass (given zero error anywhere else as the norm of the total error vector is tested).

https://www.cocosimulator.org/index_hel ... /units.htm (see controllers)
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jasper
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Re: Dynamic setting Flash drum TOP oultet stream MoleFlow

Post by jasper »

Correction - if you specify scale, the absolute, not the relative, error is scaled.
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