pygfunction: A g-function calculator for Python

What is pygfunction?

pygfunction is a Python module for the calculation of thermal response factors, or g-functions, for fields of geothermal boreholes. g-functions form the basis of many simulation and sizing programs for geothermal heat pump systems. g-Functions are superimposed in time to predict fluid and ground temperatures in these systems.

At its core, pygfunction relies on the analytical finite line source solution to evaluate the thermal interference between boreholes in the same bore field. This allows for the very fast calculation of g-functions, even for very large bore fields with hundreds of boreholes.

Using pygfunction, g-functions can be calculated for any bore field configuration (i.e. arbitrarily positionned in space), including fields of boreholes with individually different lengths and radiuses. For regular fields of boreholes of equal size, setting-up the calculation of the g-function is as simple as a few lines of code. For example, the code for the calculation of the g-function of a 10 x 10 square array of boreholes (100 boreholes total):

import pygfunction as gt
import numpy as np
time = np.array([(i+1)*3600. for i in range(24)]) # Calculate hourly for one day
boreField = gt.boreholes.rectangle_field(N_1=10, N_2=10, B_1=7.5, B_2=7.5, H=150., D=4., r_b=0.075)
gFunc = gt.gfunction.gFunction(boreField, alpha=1.0e-6, time=time)
gFunc.visualize_g_function()

Once the g-function is evaluated, pygfunction provides tools to predict borehole temperature variations (using load aggregation methods) and to evaluate fluid temperatures in the boreholes for several U-tube pipe configurations.

Requirements

pygfunction was developed and tested using Python 3.7. In addition, the following packages are needed to run pygfunction and its examples:

• matplotlib (>= 3.5.1),
• numpy (>= 1.21.5)
• scipy (>= 1.7.3)
• SecondaryCoolantProps (>= 1.1)

The documentation is generated using Sphinx. The following packages are needed to build the documentation:

• sphinx (>= 4.4.0)
• numpydoc (>= 1.2.0)

Quick start

Users - Download pip and install the latest release:

pip install pygfunction

Alternatively, download the latest release and run the installation script:

pip install .

Developers - To get the latest version of the code, you can download the repository from github or clone the project in a local directory using git:

git clone https://github.com/MassimoCimmino/pygfunction.git

Install pygfunction in development mode (this requires pip >= 21.1):

pip install --editable .

Once pygfunction is copied to a local directory, you can verify that it is working properly by running the examples in pygfunction/examples/.

Documentation

pygfunction's documentation is hosted on ReadTheDocs.

License

pygfunction is licensed under the terms of the 3-clause BSD-license. See pygfunction license.

Contributing to pygfunction

You can report bugs and propose enhancements on the issue tracker.

To contribute code to pygfunction, follow the contribution workflow.

Contributors

Massimo Cimmino 💻 📖 💡 :rocket: 🤔 🚧 👀

Jack Cook 💻 💡 🤔 📖

Matt Mitchell 💻 🤔

Wouter Peere 💻 🤔 🐛

Tobias Blanke 💻 🤔 🐛

This project follows the all-contributors specification. Contributions of any kind welcome!