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Hysys Dynamic Simulation, Negative Mass Flow

dynamcis aspenhysys flow

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#1 Seung


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Posted 22 September 2022 - 06:25 AM



I want to simulate a two stage brayton cycle with Aspen HYSYS V11 for H2 liquefaction plant.

So, I build a simple two stage example and run it. But, when I start it  in dynamcis, it has a negative mass flow (seems like flow is reversed).


It looks good in steady state (with 204 g/s of helium). How can I fix it ??


This is my flowsheet and workbook

Attached Files

Edited by Seung, 22 September 2022 - 06:29 AM.

#2 Pilesar


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Posted 22 September 2022 - 01:41 PM

Try putting a flow control loop in the dynamic simulation. Dynamic simulations are picky about details. It may be worth your time reviewing some training materials.

#3 latexman


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Posted 22 September 2022 - 02:01 PM

I use a simulator occaisionally.  I am no expert.  And, I have never used a dynamic simulator.  The mass/molar flow is positive.  That's good.  The temperature of the stream is decreasing from start/inlet to finish/outlet.  That's good.  And, the heat flow is decreasing from start/inlet to finish/outlet, which, in my mind, aligns with the temperature decreasing.  Yes, steady-state looks good.


Try putting a check valve in the line.

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