TYPES OF COOLING TOWERS CLASS NOTES
Cooling towers cool the hot water from
the condenser for reuse. A cooling tower
reduces the cost of water used in
condenser. Use of water in the condenser
is for condensing refrigerant for medium
cooling plants. Cooling tower is a
special type of heat exchanger. In this, hot
water and atmospheric air come in
direct physical contact. Air heats up
& water gets cooled. Thus, some amount
of water evaporates and goes
away with air. Water cooled
condensers require cooling towers. Thus,
power plants, chemical processing
industries and steel mills use cooling towers.
Types of Cooling Towers
Relative flow of water and air classify cooling towers. These are cross flow, counter flow and hyperbolic types. These are also classified on how air enters drawn into it. These have natural, induced, forced & balanced drafts of air.
Cross flow cooling tower
Water falls down vertically downwards. Air is blown in a perpendicular direction to the flowing water.
Counter flow type
Water falls down and air goes up.
This type is due the shape of the cooling tower. It is like a natural draft type. It uses a fan. Its shape increases the flow of air. Cooling is obtainable with evaporative cooling. It finds use in nuclear and power plants. These are vertical thus compact. Its efficiency is extremely high.
(i) Natural draft cooling tower
Uses no blower.
(ii) Forced draft cooling tower
When a blower from below introduces air into the cooling tower.
(iii) Induced draft cooling tower
When a blower is placed at the top of the cooling tower & sucks air into it.
(iv) Balanced cooling tower
When uses both induced and forced drafts.
Out of these cooling towers, natural and forced cooling towers are more common in refrigeration and air conditioning.
Advantages of a cooling tower
(i) Significantly reduces the cost of water used in the condenser.
Normally mount it on the roof of a building. It is in the vertical orientation.
Difference between Natural Draft and Forced Draft Cooling Towers
Natural Draft Cooling Tower
Forced Draft Cooling Tower
Natural air using free convection cools hot water of the condenser.
Air with a blower cools hot water of the condenser.
It is widely open on sides.
It is less open on sides.
It occupies more space.
It occupies less space and hence is compact.
It is less efficient.
It is more efficient.
It is cheap.
It is costly.
Install it in the open space where natural air is available freely.
Install it at the roof of the building.
Used for less refrigeration requirements.
Used for large refrigeration requirements.