Include short-term effects in sizing

[wouterpeere]

Right now, GHEtool ignores the internal capacity of the borehole, by making use of the equivalent borehole thermal resistance. This short-term effects however, can play an important role in some cases.

A resistance-capacitance model can be implemented like the one from (Minaei and Maerefat, 2017).

[wouterpeere]

A first short-term effect (cylindrical correction) was added in issue #187

[LoneMeertens]

Validation will done on two levels

• Inter software tool (and other GHEtool methods) comparison based on Add validation based on Ahmadfard & Bernier #243
• Dynamic simulation model (ibpsa modelica borehole model)

Next steps should focus on the following improvements:

• Develop a more general method for determining the far field radius that is applicable to non-rectangular shapes.
• Calculate the fluid factor based on the borehole configuration.
• Extend the numerical model to be able to handle double u-tubes

The sensitivity analysis should consider the following parameters:

• Borehole spacing
• The num_intervals parameter in the numerical model
• Time step used in numerical model