The attached upstream and downstream piping systems are
dealt with as individual networks of piping, fittings and other
equipment (e.g. other heat exchangers, vessels, pumps, valves, etc.).
The dynamics occurring in these systems are triggered by changes
in the pressure in the shell of the exchanger under evaluation. That
is, one of the boundary conditions imposed on either piping system
is the variation in the pressure at the respective connecting flanges
to the exchanger under evaluation. The other boundary conditions
are those prevailing at all other ends (e.g. far upstream, and far
downstream) of the respective cooling or heating piping systems.
The dynamics in these two systems can be described by the onedimensional
conservation equations of the flow through each
piping element as follows Botros and van Hardveld (2012):