What are the main types of heat exchangers and their applications?

Major types include: Shell-and-tube (most common in refineries, power plants due to high pressure/temperature capability), Plate heat exchangers (compact, high efficiency, used in HVAC, dairy industry), Double-pipe (simple, small capacity applications), Finned-tube (air-cooled condensers, car radiators), and Regenerators (gas turbines, steel plants). Selection depends on fluid types, pressure/temperature requirements, space constraints, and maintenance accessibility. Shell-and-tube can handle fouling better, while plate exchangers offer higher effectiveness in a smaller footprint.