Radiator (engine cooling)

Radiators are heat exchangers used for cooling internal combustion engines, mainly in automobiles but also in piston-engined aircraft, railway locomotives, motorcycles, stationary generating plants or any similar use of such an engine. Internal combustion engines are often cooled by circulating a liquid called engine coolant through the engine block and cylinder head where it is heated, then through a radiator where it loses heat to the atmosphere, and then returned to the engine.

Source: Wikipedia — Radiator (engine cooling) (CC BY-SA 4.0)