Cooling Tower
A cooling tower is a heat rejection device that removes waste heat from a water stream (usually from industrial processes or HVAC systems) by evaporative cooling. It transfers heat to the atmosphere, allowing the cooled water to be recirculated.
Types of Cooling Towers
1. Based on Air Flow Generation
- Natural Draft Cooling Tower
- Uses buoyancy-driven airflow (no fans).
- Large hyperbolic shape (common in power plants).
- Low operating cost but high initial cost.
- Mechanical Draft Cooling Tower
- Uses fans to force or induce airflow.
- Forced Draft: Fan at the air inlet (noisy, high maintenance).
- Induced Draft: Fan at the air outlet (more efficient, common in industries).
2. Based on Heat Transfer Method
- Wet Cooling Tower (Evaporative Cooling)
- Water contacts air directly, causing evaporation and cooling.
- Most efficient but requires water treatment to prevent scaling & algae.
- Dry Cooling Tower (Air-Cooled)
- Uses finned tubes (no water loss, but less efficient).
- Common in water-scarce regions.
- Hybrid Cooling Tower
- Combines wet & dry cooling for efficiency and water savings.
Working Principle
- Hot Water Inlet – Warm water from the process is pumped to the top.
- Distribution System – Spray nozzles or fill media spread water to maximize surface area.
- Airflow – Air passes over/through the water, causing evaporation and cooling.
- Cooled Water Collection – Cold water collects at the basin for recirculation.
- Heat Discharge – Warm, moist air exits the tower.
Key Components
- Fill Media – Increases water-air contact (splash or film type).
- Drift Eliminators – Prevent water droplets from escaping with air.
- Fans – Move air (forced/induced draft).
- Water Distribution System – Evenly spreads water.
- Basin – Collects cooled water.
Applications
- Power Plants (condenser cooling in steam cycles).
- HVAC Systems (large buildings, data centres).
- Oil Refineries & Chemical Plants.
- Manufacturing (steel, plastics, food processing).