Thermonet Dimensioning Tool

The tool can be used to dimension the diameters of gridpipes in a thermonet as well as the length of Borehole Heat Exchangers (BHES) or Horizontal Heat Exchangers (HHEs) supplying the grid.

Input

Inputs are supplied by a combination of plain text data files and input parameters for class objects (e.g. brine, BHEs etc.). Please refer to the accompanying example files.

Input parameters for class objects are defined below:

Brine

Var	Description	Unit
rho	density	[kg/m3]
c	specific heat	[J/kg K]
mu	dynamic viscosity	[Pa s]
l	thermal conductivity	[W/m K]

Thermonet

Var	Description	Unit
D_gridpipes	distance between forward/return pipe centers	[m]
l_p	pipe thermal conductivity	[W/m K]
l_s	soil thermal conductivity	[W/m K]
rhoc_s	soil volumetric heat capacity	[J/m3 K]
z_grid	burial depth of grid pipes	[m]
T0	yearly average surface temperature	[°C]
A	amplitude of sinusoidal yearly temperature variation	[°C]

Heatpump and aggregated load

Var	Description	Unit
Ti	inlet temperature	[°C]
f_peak	Fraction of peak load supplied by heatpumps	[-]
t_peak	duration of peak load	[h]

Borehole Heat Exchangers (BHE)

Var	Description	Unit
q_geo	geothermal heat flux	[W/m2]
r_b	borehole radius	[m]
r_p	U-pipe outer radius	[m]
SDR	U-pipe SDR value	[-]
l_ss	average soil thermal conductivity along BHE	[W/m K]
rhoc_ss	average soil volumetric heat capacity along BHE	[J/m3 K]
l_g	grout thermal conductivity	[W/m K]
rhoc_g	grout volumetric heat capacity	[J/m3 K]
D_pipes	U-pipe wall to wall distance	[m]
NX	Number of BHEs in x-direction	[-]
D_x	Spacing between BHEs in x-direction	[m]
NY	Number of BHEs in y-direction	[-]
D_y	Spacing between BHEs in x-direction	[m]
gFuncMethod	method for evaluating g-function	N/A

Note the gFuncMethod is a string input, and may currently be set to 'ICS' for Infinite Cylinder Source or 'PYG' for the pygfunction implementation of the finite line source. If no input is given the default is 'ICS'.

Horizontal Heat Exchangers (HHE)

Var	Description	Unit
N_HHE	Number of HE loops	[-]
d	outer diameter of HE pipes	[m]
SDR	SDR values for HE pipes	[-]
D	pipe segment spacing	[m]

Getting started

Download the latest version of the code from github. Navigate to the base folder (the folder that contains the file setup.py) and install

pip install -e .

You should now be able to run the examples provided in \src\thermonet\dimensioning\examples