A heat exchangeris a device designed to efficiently transfer thermal energy between two or more fluids (liquids or gases) without mixing them. Widely used in industries such as HVAC, power generation, chemical processing, and refrigeration, heat exchangerscome in various types, including shell-and-tube, plate, double-pipe, and air-cooled designs. They optimize heat transfer through conductive surfaces (tubes, plates, or fins) while maintaining separation between hot and cold media. Key performance factors include thermal efficiency, pressure drop, fouling resistance, and material compatibility (e.g., stainless steel for corrosion resistance). Advanced applications leverage compact designs (like microchannel exchangers) and smart controls to enhance energy recovery and reduce operational costs in systems ranging from industrial boilers to automotive radiators.