API

Module for fluid property diagram creation.

This file is part of project fluprodia (github.com/fwitte/fluprodia). It’s copyrighted by the contributors recorded in the version control history of the file, available from its original location src/fluprodia/fluid_property_diagram.py

SPDX-License-Identifier: MIT

class fluprodia.fluid_property_diagram.FluidPropertyDiagram(fluid, backend=None)

Bases: object

Short summary.

Parameters:

• fluid (str) – Fluid for diagram.

• width (float) – Width of all diagrams (default value: width=16.0).

• height (float) – Height of all diagrams (default value: height=10.0).

Example

This is a small example of how to create a fluid property dataset for water and export to Ts-, hs- and logph-diagram.

>>> from fluprodia import FluidPropertyDiagram
>>> import matplotlib.pyplot as plt
>>> import numpy as np
>>> diagram = FluidPropertyDiagram('water')

After object creation it is possible to specify isolines. There are default isolines available, but these might not suit your requirements. We will define temperature and enthalpy isolines for this case. Before that, we need to specify the units if we do not want to use SI units. For available units see the fluprodia.fluid_property_diagram.FluidPropertyDiagram.set_unit_system() documentation.

>>> diagram.set_unit_system(T='°C', p='MPa', s='kJ/kgK', h='kJ/kg')
>>> iso_T = np.arange(50, 701, 50)
>>> iso_h = np.arange(0, 3601, 200)
>>> diagram.set_isolines(T=iso_T, h=iso_h)

Now we can calculate the diagram data and create the diagram, the data should be plotted to. If you want to plot additional data to your diagram, first call the draw_isolines method, and then plot your data.

>>> diagram.calc_isolines()

After that it is possible to specify the view range of the plot and draw the isolines of a specific type of diagram. Last step is to export your diagram. Any file format supported by matplotlib is possible.

>>> fig, ax = plt.subplots(1)
>>> diagram.draw_isolines(diagram_type='Ts', fig=fig, ax=ax, x_min=0, x_max=8, y_min=0, y_max=700)
>>> plt.tight_layout()
>>> fig.savefig('Ts_Diagramm.pdf')

If we want to create a different diagram, e.g. hs-diagram, it is not necessary to recalculate the isolines. Instead, create a new figure and draw the isolines for a different diagram.

>>> fig, ax = plt.subplots(1, figsize=(8, 5))
>>> diagram.draw_isolines(diagram_type='hs', fig=fig, ax=ax, x_min=0, x_max=8, y_min=0, y_max=3600)
>>> plt.tight_layout()
>>> fig.savefig('hs_Diagramm.pdf')

>>> fig, ax = plt.subplots(1, figsize=(8, 5))
>>> diagram.draw_isolines(diagram_type='logph', fig=fig, ax=ax, x_min=0, x_max=3600, y_min=1e-2, y_max=5e2)
>>> plt.tight_layout()
>>> fig.savefig('logph_Diagramm.pdf')

It is also possible to specify/modify the isolines to plot. For example, the lines of constant specific enthalpy should be plotted in red color and with a linewidth of 2. Also, the lines of constant specific volumen should not be plotted at all. For more information see the fluprodia.fluid_property_diagram.FluidPropertyDiagram.draw_isolines() method.

>>> fig, ax = plt.subplots(1)
>>> diagram.draw_isolines(
...     diagram_type='Ts', fig=fig, ax=ax,
...     isoline_data={
...         'h': {
...            'values': iso_h,
...            'style': {'linewidth': 2, 'color': '#ff0000'}
...         }, 'vol': {'values': np.array([])}},
...     x_min=0, x_max=8, y_min=0, y_max=700
... )
>>> plt.tight_layout()
>>> fig.savefig('Ts_Diagramm.pdf')

It is also possible to export the data of a diagram:

>>> diagram.to_json("./tmp/water.json")

And, if you have your data ready to use, you can import the data again like this:

>>> diagram = FluidPropertyDiagram.from_json("tmp/water.json")
>>> diagram.fluid
'water'
>>> len(diagram.pressure["isolines"])
20

calc_individual_isoline(isoline_property=None, isoline_value=None, isoline_value_end=None, starting_point_property=None, ending_point_property=None, starting_point_value=None, ending_point_value=None)

Return data points of an individual isoline within.

Pass the isoline type, its value in the diagrams unit system, as well as the start and the endpoint of the line. Styling can be changed using the line_style property.

Parameters:

• isoline_property (str) – Type of the isoline. Choose from line_type='...':

  • pressure ('p')

  • specific volume ('vol')

  • temperature ('T')

  • enthalpy ('h')

  • entropy ('s')

• isoline_value (float) – Value of the isoline specified in the respective unit.

• starting_point (dict) – Dictionary holding the starting property and its value in the unit used for plotting the diagram, e.g. starting_property{'p': 1e5}

• ending_point (dict) – Dictionary holding the ending property and its value in the unit used for plotting the diagram, e.g. ending_property{'p': 1e4}

Returns:

datapoints (dict) – Dictionary holding the isoline datapoints for:

• pressure (key=:code:’p’)

• specific volume (key=:code:’vol’)

• temperature (key=:code:’T’)

• enthalpy (key=:code:’h’)

• entropy (key=:code:’s’)

Example

A full example can be found in the class documentation.

calc_isolines()

Calculate all isolines.

clear_isolines()

convert_from_SI(value, property)

Convert a value from SI to the active unit.

Delegates to fluprodia._units.Units.from_SI(). Works on scalars and NumPy arrays alike.

convert_to_SI(value, property)

Convert a value from the active unit to SI.

Delegates to fluprodia._units.Units.to_SI(). Works on scalars and NumPy arrays alike.

draw_isolines(fig, ax, diagram_type, x_min, x_max, y_min, y_max, isoline_data=None, latex_units=True)

Draw the isolines onto an axes within a matplotlib figure

Parameters:

• fig (matplotlib.pyplot.figure) – Figure to draw into

• ax (matplotlib.pyplot.axes) – Axes to draw into

• diagram_type (str) – Name of the diagram

• x_min (number) – Minimum for x range

• x_max (number) – Maximum for x range

• y_min (number) – Minimum for y range

• y_max (number) – Maximum for y range

• isoline_data (dict, optional) – Dictionary holding additional data on the isolines to be drawn, by default None. These are per isoline type

  • the isoline values with key values,

  • the isoline style with key style,

  • the number of labels per isoline labels_per_line (default: 1) and

  • label every n-th line only label_every_nth (default: 1)

  following this structure: {“Q”: {“values”: np.array([0.0, 1.0])}}

  The islonline style is another dictionary holding keyword arguments of a matplotlib.lines.Line2D object. See https://matplotlib.org/stable/api/_as_gen/matplotlib.lines.Line2D.html for more information.

• latex_units (bool, optional) – Axis and isoline labels using LaTeX style units, by default True

draw_isolines_plotly(diagram_type, x_min, x_max, y_min, y_max, isoline_data=None)

Draw isolines and return a plotly.graph_objects.Figure.

The interface mirrors draw_isolines(). Isoline styles are specified with the same matplotlib-style keys (color, linewidth, linestyle) and are mapped to plotly equivalents internally.

Parameters:

• diagram_type (str) – Name of the diagram, same choices as for draw_isolines().

• x_min (number) – Minimum for x range.

• x_max (number) – Maximum for x range.

• y_min (number) – Minimum for y range.

• y_max (number) – Maximum for y range.

• isoline_data (dict, optional) – Same structure as for draw_isolines(). The style sub-dict accepts color, linewidth and linestyle (matplotlib keys; mapped to plotly line.color, line.width and line.dash respectively).

Returns:

plotly.graph_objects.Figure – Fully configured figure; add further traces to overlay custom data (e.g. state points from a cycle simulation).

classmethod from_json(path)

set_isolines(**kwargs)

Set the isolines.

Parameters:

• p (ndarray) – Isolines for pressure.

• T (ndarray) – Isolines for temperature.

• Q (ndarray) – Isolines for vapor mass fraction.

• s (ndarray) – Isolines for specific entropy.

• h (ndarray) – Isolines for specific enthalpy.

• vol (ndarray) – Isolines for specific volume.

set_isolines_subcritical(T_min, T_max)

set_unit_system(units=None, **kwargs)

Set the unit system for the fluid properties.

Delegates to fluprodia._units.Units.set_defaults(). Any pint-compatible unit string that is dimensionally consistent with the property is accepted.

Both short-form keys (p, T, vol, h, s, Q) and long-form keys (pressure, temperature, volume, enthalpy, entropy, quality) are supported.

A tespy.tools.units.Units instance (or any object with a default attribute that is a plain dict) may be passed as the first positional argument. Keyword arguments are merged on top and take precedence. tespy properties that have no fluprodia equivalent (e.g. mass_flow, power) are silently ignored.

Parameters:

• units (object, optional) – An object with a default dict, e.g. network.units from a tespy simulation. Its entries are used as base values; any **kwargs override them.

• p / pressure (str) – Unit of pressure, e.g. 'Pa', 'bar', 'MPa'.

• T / temperature (str) – Unit of temperature, e.g. 'K', '°C', '°F'.

• s / entropy (str) – Unit of specific entropy, e.g. 'J/kgK', 'kJ/kgK'.

• h / enthalpy (str) – Unit of specific enthalpy, e.g. 'J/kg', 'kJ/kg'.

• vol / volume / specific_volume (str) – Unit of specific volume, e.g. 'm^3/kg', 'l/kg'.

• Q / quality (str) – Unit of vapour quality, e.g. '-', '%'.

to_json(path)

Export the diagram data as json file to a path.

Parameters:

path (str, path-like) – Name of the file to export the data to.