Gas mixture simon

[kbensafta]

This PR rectifies the gas mixture compressiblity calculation and merges the changes from the master branch in the kbensafta:gas_mixture_simon branch to make the latter pass the tests.

The SRK method has been implemented for the compressibility calculation (see G. Soave, Equilibrium constants from a modified Redlich-Kwong equation of state). The new function is calculate_mixture_compressibility_fact in properties_toolbox.py. Among other changes, the gas mixture compressibility takes now the temperature into account. A test has been added (test_compressibility in pandapipes/test/api/test_special_networks.py) to compare the results of the calculation with CoolProp results.

Minor changes:

• rectification of the calculate_molar_fraction_from_mass_fraction function (also in properties_toolbox.py)
• add critical data to the fluids text files and (critical temperature, critical pressure and acentric factor) to the Fluid class.

Note: The folder tests_gas_mix is not necessary and have to be ignored during the final PR to the develop branch. SRK_TEST.ipynb contains the script that produces the CoolProp results for the compressiblity. This could/should be saved somewhere outside of the pandapipes repository.

[jkisse]

Can you make the tests pass, e.g. by merging the current develop into this PR? (or at least delete Python 3.7 from the test pipeline)

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 81.93018% with 616 lines in your changes are missing coverage. Please review.

Project coverage is 83.55%. Comparing base (f9b7cb0) to head (1623ae4). Report is 67 commits behind head on gas_mixture.

:exclamation: Current head 1623ae4 differs from pull request most recent head 9a8fb85. Consider uploading reports for the commit 9a8fb85 to get more accurate results

Files	Patch %	Lines
pandapipes/converter/stanet/table_creation.py	66.11%	184 Missing :warning:
pandapipes/create.py	72.22%	70 Missing :warning:
pandapipes/properties/fluids.py	48.00%	65 Missing :warning:
pandapipes/converter/stanet/preparing_steps.py	81.30%	43 Missing :warning:
pandapipes/properties/properties_toolbox.py	68.61%	43 Missing :warning:
pandapipes/std_types/std_type_class.py	64.03%	41 Missing :warning:
...es/multinet/control/controller/multinet_control.py	48.14%	28 Missing :warning:
pandapipes/component_models/pump_component.py	77.27%	20 Missing :warning:
pandapipes/pf/derivative_toolbox_numba.py	25.00%	18 Missing :warning:
pandapipes/converter/stanet/stanet2pandapipes.py	78.20%	17 Missing :warning:
... and 21 more

Additional details and impacted files

@@               Coverage Diff               @@
##           gas_mixture     #550      +/-   ##
===============================================
- Coverage        87.07%   83.55%   -3.53%     
===============================================
  Files               79       93      +14     
  Lines             4681     7277    +2596     
===============================================
+ Hits              4076     6080    +2004     
- Misses             605     1197     +592     

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