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IDAES / examples-pse

(ARCHIVED - use IDAES/examples) Example Python code, Jupyter Notebooks, and other files for the IDAES PSE
https://idaes.github.io/examples-pse/
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Fix NGCC + SOEC cost optimization #158

Closed eslickj closed 1 year ago

eslickj commented 1 year ago

Fixes # .

The cost optimization was failing for the NGCC + SOEC flowsheet. I found two problems.

  1. There were what a comments said were dummy variables for length and diameter of the SOEC module. They were initialized to zero but not fixed. I'm not sure but I think they were there so that the SOEC costing could be build on a generic vessel costing block. After adding the capital costing equations there were two extra degrees of freedom, which I think were probably the SOEC length and diameter. I fixed them, but fixing them to 0 failed, so I fixed them to 0.1 m which should be small enough to not matter. I assume the reason 0 didn't work is that there is a positive lower bound on vessel weight.
  2. The costing constraints and variables were really badly scaled, so I tried to improve the scaling. I got the condition number of the problem from 3e20 to 2e9.

This fixes the convergence issues, but the result is a bit deferent than the results recored in the SOFC-IES report. There isn't a huge difference. I'm not sure if there were changes to the SOEC model or the Costing framework or some other mystery change. After the report QC, I think we should add some asserts to make sure know if the results change.

This PR replaces #157.

Proposed changes:

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eslickj commented 1 year ago

You can see the changes in the costing file ngcc_soec_costing.py, but the notebook, you can't really see the changes. I just added a bunch or scaling factors. The rest is just making sure the saved states are up to date.