v0.2.2 - Rankine's Realm (March, 6, 2020)
+++++++++++++++++++++++++++++++++++++++++

New Features
############
- Allow initialisation for the primary variables from previous calculation.
  Until now, the user needed to save the network's state and reload that state
  for his next simulation. This feature is enabled as default. If you want to
  disable this feature, you need to state
  :code:`mynetwork.solve(..., init_previous=False)`
  (`PR #156 <https://github.com/oemof/tespy/pull/156>`_).
- Extrapolation for characteristic lines is available. In default state, the
  upper or lower value range limit is used when a characteristic line is
  evaluated outside of the available x-value range. The :code:`extrapolate`
  parameter allows linear extrapolation, for an example see the corresponding
  sections in the online documentation:
  :ref:`component characteristics <component_characteristic_specification_label>`,
  :ref:`tespy characteristics <tespy_modules_characteristics_label>`
  (`PR #159 <https://github.com/oemof/tespy/pull/159>`_).
- Add a new component evaporator for geothermal organic rankine cycle. The
  component has inlets for geothermal steam brine. On the cold side, the orc
  working fluid is evaporated. Read more about this component in the API
  documentation: :py:class:`tespy.components.customs.orc_evaporator`
  (`PR #148 <https://github.com/oemof/tespy/pull/148>`_).

Documentation
#############
- Add method for automatic citations and references
  (`PR #163 <https://github.com/oemof/tespy/pull/163>`_).

Parameter renaming
##################

Testing
#######
- Add convergence checks for all component tests. Some tests did not fail, even
  if the calculation did not converge
  (`PR #153 <https://github.com/oemof/tespy/pull/153>`_).
- Improve coverage of the networks module
  (`PR #153 <https://github.com/oemof/tespy/pull/153>`_).
- Add tests for characteristic line and map evaluation
  (`PR #159 <https://github.com/oemof/tespy/pull/159>`_).

Bug fixes
#########
- Fix the bugged tests for compressor characteristic maps
  (:py:meth:`tespy.components.turbomachinery.compressor.char_map_func`). The
  pressure ratio factor of the lowest speedline available in the default data
  ranges from about 0.2 to 0.5. Therefore the design pressure ratio should be
  higher than 5 (`PR #156 <https://github.com/oemof/tespy/pull/156>`_).

Other changes
#############
- Use the method :py:meth:`tespy.components.components.component.fluid_deriv`
  for all components, that do not change composition between an inlet and the
  respective outlet (`PR #153 <https://github.com/oemof/tespy/pull/153>`_).
- Adjust the method :py:meth:`tespy.components.components.component.zeta_func`
  to work with all zeta value specifications
  (`PR #153 <https://github.com/oemof/tespy/pull/153>`_).

Contributors
############
- Francesco Witte (`@fwitte <https://github.com/fwitte>`_)
- `@maltefritz <https://github.com/maltefritz>`_
- `@ChaofanChen <https://github.com/ChaofanChen>`_
