A shell and tube heat exchanger (STHE) is a type of heat exchanging device constructed using a large cylindrical enclosure, or shell that has bundles of perfectly spaced tubing compacted in its interior. Heat exchanging is the transfer of heat from one substance or medium to a similar substance or medium. Shell and tube heat exchangers are the most common form of heat exchange design. They are classified according to their properties, tubing type, and other characteristics.