What is the working principle of heat exchangers?

Heat Transfer is one of the most important industrial processes. Throughout any industrial facility, heat must be added, removed, or moved from one process stream to another. There are three basic types of Heat Transfer: conduction, convection and radiation. A heat exchanger is a system used to transfer heat between a source and a working fluid. A finned tube heat exchanger are used in both cooling and heating processes. A heat exchanger typically involves two flowing fluids separated by a solid wall. Many of the heat transfer processes encountered in industry involve composite systems and even involve a combination of both conduction and convection.

All heat exchangers do the same job—passing heat from one fluid to another—but they work in many different ways. The two most common kinds of heat exchanger are the shell-and-tube and plate/fin. Shell and Finned tube heat exchangers consist of a series of tubes which contain fluid that must be either heated or cooled. The usage of fins in a tube-based heat exchanger is common when one of the working fluids is a low-pressure gas, and is typical for heat exchangers that operate using ambient air.