The CarrollNode is a composant only used for a better
graphical representation. With the carroll method to treat
radiative exchanges, all the surfaces exchange with a fictive node
(see figure bellow). To avoid to connect all the
CarrollRadiation modules together to get the ficitve node,
there are all connected to the CarrollNode module. It is less
confusing for the understanding of the user than multiple graphical
connections everywhere.
By flow conservation, this node has a zero flow balance at its heat
port. Therefore, the temperature of its heat port is the Mean
Radiant Temperature (MRT). This node corresponds to the 'Jmrt'
point on the figure bellow (picked up from the FviewCalculator
description)