Heat Exchanger are devices to enhance or facilitate the flow of heat. Heat Exchanger used to transfer heat between two or more streams of fluid. Tubular heat exchanger are found in the great majority of applications, primarily for historical and economic reason. They have been in use for a long time and are familiar to many engineers. Standard models are available in a wide range of capacities at reasonable cost, as are the custom made units found in oil refineries and chemical process plants and in the power industries.
The best know standards for tubular heat exchanger are the Tema standards of the Tubular Exchanger Manufactures Association, which include a basic nomenclature and classification scheme for tube and shell heat exchanger.