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Cooling towers are classified based on their airflow mechanism, design, and heat transfer method. Here are the main types of cooling towers:

1. Based on Airflow Generation

A. Natural Draft Cooling Tower

• Uses natural convection (no fans).
• Hot air rises due to buoyancy, pulling in cooler air at the base.
• Types:
  • Hyperbolic towers (common in power plants).
  • Rectangular towers (less common).
• Advantages: Low energy Disadvantages ConsConsumtion, high capacity.
• Disadvantages: Huge structure, expensive to build.

B. Mechanical Draft Cooling Tower

• Uses fans to force or induce airflow.
• Types:
  • Forced Draft
    • Fan at the bottom pushes air upward.
    • More efficient but noisy.
  • Induced Draft
    • Fan at the top pulls air through the tower.
    • More common, less noise, better air distribution.
• Advantages: Compact, controllable airflow.
• Disadvantages: Higher energy use than natural draft.

2. Based on Water & Air Flow Direction

A. Crossflow Cooling Tower

• Air flows horizontally across falling water.
• Gravity distribution (no spray nozzles needed).
• Advantages: Lower pump pressure, easy maintenance.
• Disadvantages: Larger footprint.

B. Counterflow Cooling Tower

• Air flows upward, opposite to falling water.
• Uses spray nozzles for better water distribution.
• Advantages: More efficient, smaller footprint.
• Disadvantages: Higher pump pressure required.

3. Based on ConsConstruction of Material

A. Wooden Cooling Towers

• Used in older systems (rare today).
• Prone to decay and fire hazards.

B. Fiberglass (FRP) Cooling Towers

• Lightweight, corrosion-resistant.
• Common in industrial applications.

C. Concrete Cooling Towers

• Used in large power plants.
• Durable but expensive.

D. Metal (Steel/Stainless Steel) Cooling Towers

• Used in harsh environments.
• Resistant to corrosion but costly.

4. Based on Heat Transfer Method

A. Open (Wet) Cooling Tower

• Direct contact between air & water.
• Advantages : High efficiency, lower cost.
• Disadvantages : Water loss due to evaporation, scaling, and biological growth.

B. Closed-Circuit (Dry) Cooling Tower

• Uses a heat exchanger (no direct water-air contact).
• Advantages: No water loss, minimal scaling.
• Disadvantages: Higher initial cost, less efficient than wet towers.

C. Hybrid (Wet/Dry) Cooling Tower

• Combines wet & dry cooling for efficiency.
• Reduces water usage while maintaining performance.

5. Specialized Types

• Field-Erected Cooling Towers (Large, built on-site for power plants).
• Package Cooling Towers (Prefabricated, small-scale for HVAC).
• Evaporative Cooling Towers (Uses evaporation for cooling).
• Dry Cooling Towers (Uses only air, no water loss—common in water-scarce areas).

Which Type is Best?

• Power plants → Natural draft or large induced draft.

Industries → Mechanical draft (crossflow/counterflow