A shell and tube heat exchanger is a cylindrical vessel
housing a set of tubes (called the tube bundle) containing
a fluid at some temperature and immersed in another
fluid at a different temperature. The transfer of heat
occurs between the fluid flowing over the tubes and the
fluid flowing inside the tubes. The fluid flow inside the
tubes is said to be “tube side” and the fluid flow external
to the tube bundle is said to be “shell side”.
While there is an enormous variety of specific design
features that can be used in shell and tube exchangers,
the number of basic components is relatively small.