Induced Draft Cooling Tower
An Induced Draft Cooling Tower is a mechanical draft cooling tower in which the fan is placed at the top of the tower. The fan pulls (induces) air upward through the fill and discharges it into the atmosphere at a high velocity.
It is the most commonly used cooling tower type in industries and HVAC systems.
Working Principle
- Hot water inlet – Warm water from the plant/condenser enters the tower and is sprayed over the fill media.
- Air movement by fan – A large fan at the top of the tower pulls air in through the louvers at the bottom/sides.
- Heat transfer – As water flows downward over the fill, it comes into contact with upward-moving air.
- A small portion of water evaporates.
- This evaporation absorbs heat from the remaining water, cooling it.
- Moist air exit – The fan at the top induces a draft and expels warm, moist air into the atmosphere at high velocity.
- Cooled water collection – The cooled water collects in the cold water basin at the bottom and is pumped back to the process.
Features
- Fan at the top → pulls air upward (induced draft).
- Ensures uniform air distribution through the fill.
- Discharges moist air at high velocity → reduces recirculation (hot air re-entering the tower).
Advantages
- More efficient than forced draft towers.
- Handles large cooling loads (power plants, industries).
- Less prone to recirculation of moist air.
- Lower power consumption compared to forced draft (fan works against less resistance).
Applications
- Power plants (thermal, nuclear, gas)
- Refineries & petrochemical plants
- HVAC systems for large buildings
- Steel, cement, and process industries