Issue 718 cooling area

[brosaplanella]

Description

The lumped thermal model now takes an option to choose between arbitrary geometry (default) or a pouch geometry. The arbitrary geometry takes a total heat transfer coefficient, surface cooling area and cell volume. The pouch geometry calculates it from the different parts of the pouch (including tabs).

Fixes #718

Type of change

Please add a line in the relevant section of CHANGELOG.md to document the change (include PR #) - note reverse order of PR #s. If necessary, also add to the list of breaking changes.

• New feature (non-breaking change which adds functionality)
• Optimization (back-end change that speeds up the code)
• Bug fix (non-breaking change which fixes an issue)

Key checklist:

• No style issues: $ flake8
• All tests pass: $ python run-tests.py --unit
• The documentation builds: $ cd docs and then $ make clean; make html

You can run all three at once, using $ python run-tests.py --quick.

Further checks:

• Code is commented, particularly in hard-to-understand areas
• Tests added that prove fix is effective or that feature works

[brosaplanella]

Oh yes, in that case it makes sense. Is it only for dimensionality = 2 x-lumped model? Do we want to throw an error or just a warning?

[rtimms]

the x-lumped models assume a pouch cell for conditionality 1 and 2. I think it would be good to raise an option error. If people really want to to do it they can bypass the option error by manually changing submodels

[brosaplanella]

Actually, x-lumped models of higher dimension already assume pouch (I have only implemented arbitrary geometry for lumped models). Dimensionality 0 will fall back to the lumped model I think so then the arbitrary geometry is fine.

[rtimms]

Yeah it is probably fine as is. I was just worried that people might choose the options {"dimensionality": 2, "thermal": "x-lumped", "geometry": "arbitrary"} which at the moment silently works ok, but people might not realise that choosing "arbitrary" has no effect. Maybe there could be a setter for geometry that picks the default based on some other options (if it isn't provided). But perhaps I am unnecessarily worried and that is too complicated!