8.14.2 NATURAL CIRCULATION SYSTEM
The system is closed one and designed so that the water may circulate naturally because of the
difference in density of water at different temperatures. Fig. 8.14 shows a natural circulation cooling
system. It consists of water jacket, radiator and a fan. When the water is heated, its density decreases and
it tends to rise, while the colder molecules tend to sink. Circulation of water then is obtained as the water
heated in the water jacket tends to rise and the water cooled in the radiator with the help of air passing
over the radiator either by ram effect or by fan or jointly tends to sink. Arrows show the direction of
natural circulation, which is slow.