A heat exchanger is a device used to transfer thermal energy between two or more fluids, which are at different temperatures. In most cases, the fluids can exchange heat without direct contact.
In the diagram below, fluid 1 is at a low temperature, T1, and fluid ② is at a high temperature T2. Heat transfer occurs from fluid ② to fluid ①, resulting in an increase in the temperature of fluid ①.
Heat exchangers have applications in many products such as area heating, air-conditioning, chemical processing or waste heat recovery.