Natural Draft Cooling Tower
A natural draft cooling tower is a type of cooling tower that relies on the natural convection of air (without fans) to circulate air through the tower for cooling.
Working Principle
- Hot water from the plant is sprayed at the top of the tower and distributed over fill media.
- Inside the tall hyperbolic (chimney-like) tower, warm, moist air is lighter than the cooler outside air.
- This density difference creates a natural upward draft (chimney effect).
- As air rises, part of the water evaporates, absorbing heat and cooling the rest.
- The cooled water collects at the bottom basin and is pumped back to the process.
Features
- No fans → airflow depends only on temperature difference between inside moist air and outside ambient air.
- Large hyperboloid concrete structures (you often see them in power plants).
- Economical for handling very large water flow rates.
Advantages
- No fan power consumption → lower operating cost.
- Long service life (made of reinforced concrete).
- Suitable for very large power plants & industries.
- Low maintenance (no moving parts like fans).