The function of the radiator explained

The function of the radiator is to ensure close contact of the hot water coming out of the engine with outside air, to ensure high rates of heat transfer from the water to air. A radiator consists of an upper tank, core and the lower tank. Besides, an overflow pipe in the header tank and a drain pipe in the lower tank are provided.

There are two basic types of radiator cores, tubular type and cellular type. In the former, it is the water that flows through tubes air passes through the tubes and water flows in the spaces in between them. Out of these, tubular type cores are the most commonly used which are further classified depending upon the shape of the fins around the tubes, which are meant to increase the area for heat transfer from water to the cooling air.

The materials used for radiators should be resistant to corrosion, possess higher thermal conductivity and form easily, apart from having adequate strength. Copper and yellow brass are the widely used materials for radiators. Aluminium is also used for weight and cost consideration.

For heavy-duty applications, radiator shutters are also sometimes used. They are automatically controlled through the compressed air taken from the brake system. The shutter control mechanism is installed with the upper hose of the cooling system. 

Depending upon the coolant temperature coming from the engine, which itself depends upon the engine temperature the shutter control mechanism causes the shutter to open to close. Thus, for example, the shutter remains closed during starting and it gradually opens up as the engine attains its working temperature, thus allowing the fresh air to come into contact with the radiator.