AC & R and many other industrial requirements run on water. This water is kept cool by the Cooling tower. Cooling tower facilitates cooling by increasing the water surface area. More the surface area, more water comes in contact with air and gets evaporate leaving behind the cool water.
On the grounds of the operations that they carry out, cooling towers are available into two basic categories, Mechanical draft cooling tower, where air draft is created through fans and Natural draft cooling tower, where air draft is generated naturally without the use of any fan.Mechanical Draft cooling tower:
There are two types of cooling towers generating the air draft mechanically, which are:
- Induced Draft: In these cooling towers, fans are placed at the top of the suction of the Cooling Tower. Again there are two verities in induced draft cooling towers: counterflow cooling tower and crossflow cooling tower. In counterflow cooling towers, the air and water run in opposite direction. Downwards flowing water generates counter currents against upward flowing air. In a cross-flow cooling tower, the water flows downwards but the slanting shape of the tower allows the air to flow in 90 degrees to water. Counterflow cooling towers offer more compactness than a cross-flow cooling tower.
Natural Draft Cooling Tower:
- Forced Draft: In these towers, the fans are placed at the side bottom to forcefully pull the air into the cooling tower in order to create the air draft.
In these towers, the shape of the tower and the difference of water density in the outlet and inlet, causes the air draft and no fans are required. For larger cooling water requirements like 40,000 CMH plus, using these towers is very profitable as these occupy less space, demand minimum maintenance and no expenditure for fans operations. But capital cost of this tower is more comparing to induced one.