Active cooling
An active cooling system can be as simple as a fan that blows air over the object to be cooled.
Or, to greatly increase its capacity to remove heat, the system may use a pump to circulate a coolant. The coolant picks up heat as it passes over or through the object that is being actively cooled (such as an automobile engine). The coolant may pass through a radiator in order to rapidly cool it before it makes another pass through the cooling system.