Baffles are commonly placed in the shell to force the
shell-side fluid to flow across the shell to enhance heat transfer and to maintain
uniform spacing between the tubes. Despite their widespread use, shelland-
tube heat exchangers are not suitable for use in automotive and aircraft
applications because of their relatively large size and weight. Note that the
tubes in a shell-and-tube heat exchanger open to some large flow areas called
headers at both ends of the shell, where the tube-side fluid accumulates before
entering the tubes and after leaving them.