encomp 0.1.9

General-purpose library for engineering computations

encomp

General-purpose library for engineering computations, with focus on clean and consistent interfaces.

Package documentation at https://encomp.readthedocs.io/en/latest/

Features

Main functionality of the encomp library:

• Handles physical quantities with a magnitude, unit and dimensionality

  • Module encomp.units, encomp.utypes
  • Extends the pint library
  • Uses Python's type system to validate dimensionalities
  • Integrates with np.ndarray and pd.Series
  • Automatic JSON serialization and decoding

• Implements a flexible interface to CoolProp

  • Module encomp.fluids
  • Uses quantities for all inputs and outputs
  • Fluids are represented as class instances, the properties are class attributes

• Extends Sympy

  • Module encomp.sympy, encomp.balances
  • Adds convenience methods for creating symbols with sub- and superscripts
  • Additional functions to convert (algebraic) expressions and systems to Python code that supports Numpy arrays

• Jupyter Notebook integration

  • Module encomp.notebook
  • Imports commonly used functions and classes
  • Defines custom Jupyter magics

The other modules implement calculations related to process engineering and thermodynamics. The module encomp.serialize implements custom JSON serialization and decoding for classes used elsewhere in the library.

This library is under work: all features are not yet implemented.

Installation

Install with pip:

pip install encomp

This will install encomp along with its dependencies into the currently active Python environment.

CoolProp is not installable with pip for Python 3.9. Install manually with conda for now:

conda install conda-forge::coolprop

Development environment

Install Miniconda or Anconda if not already installed. Clone this repository, open a terminal and navigate to the root directory. Setup a new environment using conda:

conda env create -f environment.yml

This will install the necessary dependencies into a new conda environment named encomp-env. The dependencies (except for scipy and jupyter) are installed with pip.

Install encomp into the new environment:

conda activate encomp-env
pip install .

Removing the conda environment

To completely remove the conda environment for encomp:

conda remove -y --name encomp-env --all

Getting started

To use encomp from a Jupyter Notebook, import the encomp.notebook module:

# imports commonly used functions, registers Notebook magics
from encomp.notebook import *

This will import commonly used functions and classes. It also registers the %read and %%write Jupyter magics for reading and writing custom objects from and to JSON.

Some examples:

# converts 1 bar to kPa, displays it in case it's the cell output
Q(1, 'bar').to('kPa')

# creates an object that represents water at a certain temperature and pressure
Water(T=Q(25, 'degC'), P=Q(2, 'bar'))

The Quantity class

The main part of encomp is the encomp.units.Quantity class (shorthand Q), which is an extension of pint.Quantity. This class is used to construct objects with a magnitude and unit. It can also be used to restrict function and class attribute types. Each dimensionality (for example pressure, length, time) is represented by a subclass of Quantity.

Use type annotations to restrict the dimensionalities of function parameters and return values.

In case the ENCOMP_TYPE_CHECKING environment variable is set, the typeguard.typechecked decorator is automatically applied to all functions and methods inside the main encomp library. To use it on your own functions, apply the decorator explicitly:

from typeguard import typechecked
from encomp.api import Quantity

@typechecked
def some_func(T: Quantity['Temperature']) -> tuple[Quantity['Length'], Quantity['Pressure']]:
    """
    Takes a temperature or temperature difference and
    returns length and a pressure quantities.
    """

    return T * Quantity(12.4, 'm/K'), Q(1, 'bar')

some_func(Q(12, 'delta_degC'))  # the dimensionalities check out
some_func(Q(26, 'kW'))  # raises an exception
# TypeError: type of argument "T" must be Quantity[Temperature]; got Quantity[Power] instead

The dimensionality of a quantity can be specified with string values like 'Temperature' or pint.UnitsContainer objects. To create a new dimensionality (for example temperature difference per length), combine the pint.UnitsContainer objects defined in encomp.utypes using * and /:

from encomp.api import Quantity
from encomp.utypes import Temperature, Length

qty = Quantity[Temperature / Length](1, 'delta_degC / km')

# raises an exception since liter is Length**3 and the Quantity expects Length**2
another_qty = Quantity[Temperature / Length**2](1, 'delta_degC / liter')

# create a new subclass of Quantity with restricted input units
CustomQuantity = Quantity[Temperature / Length**3]

# pint handles a wide range of input formats
CustomQuantity(1, '°F per yard³')

Settings

The attributes in the encomp.settings.Settings class can be modified with an .env-file. Place a file named .env in the current working directory to override the default settings. The attribute names are prefixed with ENCOMP_. See the file .env.example in the base of this repository for examples.

TODO

• Check compatibility with MyPy and other type checkers
  • Would be nice to see issues with dimensionality directly in the IDE
  • Might not be possible since the subclass Quantity['Temperature'] is constructed at runtime
• Combine EPANET (wntr) for pressure / flow simulation with energy systems simulations (omeof)
• Make a web interface to draw circuits (using a JS node-graph editor) and visualize results.

Ensure compatibility with

• numpy

• pandas

• Excel (via df.to_excel, both with openpyxl and xlsxwriter

  • parse units from Excel (header name like "Pressure [bar]" etc...)

• nbconvert (HTML and Latex/PDF output)

  • figure out how to typeset using SIUNITX
  • look into JupyterBook and similar projects

• http://www.thermocycle.net/

• https://github.com/topics/process-engineering

• https://github.com/oemof/tespy

• https://github.com/oemof

• https://python-control.readthedocs.io/en/0.9.0/index.html

• https://ruralwater.readthedocs.io/en/dev/readme.html