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[Bug] Dynamic modelling for water heat exchanger does not work #429
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@WYuanJun can you share the flowsheet? |
Hi Dan, The testHX6 file is the original with the problem but the "given key not present" error has somehow gone away but the model still does not show the correct temperature, pressure and mass flow as I would expect. The testHX7 file is also another model with the exact same process model I tried to recreate but with different heat exchanger parameter, UA and area but I am still not getting the correct output for temperature, pressure and flow rates. Your support and advice would be great appreciated! Thank you! |
@WYuanJun something is missing here: as for HX7, it doesn't look right indeed. I'll take a look |
Oh yes for the screenshot I had the other outlet streams from the heat exchanger before and it had the same problem as HX7 so I deleted those streams (it was named 8 & 9) so that is why it is missing from the monitored variables. Sorry I forgot I did that. Maybe that is what is causing the problem. But yes HX7 still has some issues I believe |
…am connection button in editor; fixed issue #429
@WYuanJun what exactly are you trying to control? you selected mass flow but inserted a value like 1 bar, this doesn't make sense. |
@WYuanJun it doesn't make sense to control pressure if you have only liquid in the process. |
Hi Dan You are right I should be using flow in the dynamics tab to control the flow. I guess I wasn't thinking it through at the time, but I was just trying to copy the heat exchanger example but with just water instead. For HX7 I was trying to control the outlet (stream 10) temperature to be at 50C by changing the opening of valve 3 to do so to change the flow rate to control the outlet temperature. Sorry I am not very experienced with dynamic modelling and are trying to learn. Many thanks! Cheers |
Or to control stream 12 temperature by changing the valve 3 opening. |
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IMPORTANT: This section is for code-related bugs. For usage issues, please go to the Support Forums.
Describe the bug
When trying to solve a water to water heat exchanger in dynamic mode the pressure and temperature goes out of range. The model solves in steady state mode.
It then has an error: the given key was not present in dictionary.
Note: The thermodynamic property package used is Raoult's Law. (The same problem happens in IAPWS steam table package)
To Reproduce
Steps to reproduce the behavior:
Expected behavior
I would expect the heat exchanger to find a valve opening percentage with the correct pressure and flow in dynamic mode.
Screenshots
![image](https://user-images.githubusercontent.com/125230606/218355900-19ca9981-e830-41d2-a2f5-0735c890c96f.png)
![image](https://user-images.githubusercontent.com/125230606/218355935-7571d85b-4e62-4a86-aa88-7c8516c826dd.png)
If applicable, add screenshots to help explain your problem.
Desktop (please complete the following information):
Additional context
Add any other context about the problem here.
The heat exchanger calculation type is calculate outlet temperatures (UA) mode.
This is in normal DWSIM not the Cross Platform
Many thanks
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