Heat exchangers are devices used to transfer heat from a hot fluid to a cold fluid to meet specified process requirements and are an industrial application of convective heat transfer and heat conduction. Heat exchangers can be classified in different ways. Its operation process can be divided into three main categories: inter-wall, hybrid, and heat storage. According to its surface compactness can be divided into two categories: compact and non-compact. Next, let's learn about the history of heat exchanger development.