Radiators

In automobiles with an internal combustion engine, a radiator is connected to channels running through the engine and cylinder head, through which is pumped a liquid. This liquid is typically a mixture of distilled water with ethylene glycol (a.k.a. antifreeze). The fluid moves in a closed system from the radiator to the engine, where it conducts heat away from the engine parts and carries the heat primarily to the radiator. The radiator is typically mounted behind the vehicle's grille, with outside air driven through the radiator by the vehicle's forward motion, often supplemented by a cooling fan. The radiator transfers the heat from the fluid inside to the air, thereby cooling the engine. A system of valves and/or baffles is usually incorporated to simultaneously operate a small radiator inside the car; this small radiator is called the heater core and serves to warm the interior cabin.

The size of the radiator is usually chosen so that it can keep the engine at the designed temperature under the most extreme conditions a car is likely to encounter (such as climbing a mountain, while fully loaded, on a hot day)

The invention of the automobile water radiator is attributed to Karl Benz. Some engines have an additional oil cooler; a separate small radiator to cool the motor oil. Cars with an automatic transmission often have extra connections to the radiator, allowing the transmission fluid to transfer its heat to the coolant in the radiator. Turbo charged or supercharged engines may have an intercooler, which is an air-to-air or air-to-water radiator used to cool the incoming charge and not to cool the engine.