Answer for What is the process of water getting cool in a radiator ?

In a radiator there is an upper tank and a lower tank. Both are connected by thin copper tubes. When hot water comes down from upper tank it comes into contact with the cold copper tubes. Thus the heat of water is absorbed by the copper tubes and water of normal temperature comes down into the tank and then goes into the engine again. Hot tubes keep on getting cool with the air and a fan is fixed there, which brings in air from outside the radiator.