
This models the dynamic behaviour of a shell and tube heat exchanger in order to predict the variation of temperature, with respect to both axial distance along the exchanger and flow time.
The problem involves the two independent variable, time and length. The distance variable can be eliminated by finite differencing the exchanger into N equal sized segments (N=8 in this model) of length L such that N*L = total length of the exchanger.
In this model, except for the end sections, the average temperatures of the section are used to calculate the convection terms.
Assumptions
Heat losses and heat conduction along the metal wall are assumed to be negligible, but the dynamics of the wall are significant
The length is broken into 8 segments here. Thus if the length is quite large , the user might consider breaking the length into more no. of segments to get a better result and that would imply building in more of the energy balance blocks |