A cooling tower is a heat rejection device that removes waste heat from a water stream and releases it into the atmosphere. It is commonly used in industries, power plants, and HVAC systems to cool water that has been heated by industrial processes or air conditioning systems.
How Does a Cooling Tower Work?
- Hot Water Inlet – Warm water from industrial processes or condensers is pumped into the cooling tower.
- Distribution System – The water is spread over a fill media (a structure that increases surface area for better heat transfer).
- Airflow & Evaporation – Air is drawn through the tower (either naturally or by fans), causing a small portion of the water to evaporate, which removes heat.
- Cooled Water Collection – The remaining cooled water is collected in a basin and recirculated back into the system.
- Heat Discharge – The warm, moist air is expelled into the atmosphere.
Types of Cooling Towers
- Natural Draft Cooling Tower – Uses buoyancy-driven airflow (no fans). Common in large power plants.
- Mechanical Draft Cooling Tower – Uses fans to force or induce airflow:
- Forced Draft – Fan at the base pushes air in.
- Induced Draft – Fan at the top pulls air through.
- Crossflow & Counterflow – Refers to the direction of airflow relative to water flow.
- Closed-Circuit (Dry) Cooling Tower – Uses a heat exchanger to avoid direct water-air contact.
Applications
- Power plants (nuclear, coal, gas)
- Oil refineries & chemical plants
- HVAC systems (large buildings, data centres)
- Manufacturing processes (steel, plastics, food processing)
Advantages
- Energy-efficient cooling.
- Reduces water Disadvantages Consumtion (compared to once-through cooling).
- Can handle large heat loads.
Disadvantages
- Water loss due to evaporation & drift.
Requires maintenance to prevent scaling, corrosion, and bacterial growth (e.g., Legionella