Cooling Tower - SARKARI LIBRARY

A cooling tower is a heat rejection system that removes excess heat from a building or industrial process by using water evaporation or air circulation. It is commonly used in HVAC, power plants, and manufacturing industries.

Types of Cooling Towers
Cooling towers are classified based on:
1️⃣ Airflow direction
2️⃣ Heat transfer method
3️⃣ Construction type
A. Based on Airflow Direction
- ✅ Natural Draft Cooling Tower
  🔹 Uses buoyancy (hot air rises, cold air enters).
  🔹 Used in power plants & large-scale industries.
  🔹 Advantage: No mechanical fans = Low energy cost.
  🔹 Disadvantage: Large size & high initial cost.
- ✅ Mechanical Draft Cooling Tower
  🔹 Uses fans or blowers for airflow.
  🔹 Types:
  - Forced Draft: Fans push air from bottom → top.
  - Induced Draft: Fans pull air from the top.
    🔹 Advantage: More compact & efficient.
    🔹 Disadvantage: Higher energy consumption.
B. Based on Heat Transfer Method
- ✅ Wet Cooling Tower (Open Circuit)
  🔹 Water is sprayed, and some evaporates to remove heat.
  🔹 Advantage: High cooling efficiency.
  🔹 Disadvantage: Water loss & scaling.
- ✅ Dry Cooling Tower (Closed Circuit)
  🔹 Uses air instead of water for cooling.
  🔹 Advantage: No water loss, eco-friendly.
  🔹 Disadvantage: Lower efficiency than wet cooling.
- ✅ Hybrid Cooling Tower
  🔹 Combination of wet & dry cooling.
  🔹 Advantage: Saves water & maintains efficiency.

Cooling Tower Construction
🔹 Frame & Structure → Made of steel, FRP (Fiberglass Reinforced Plastic), or concrete.
🔹 Fill Media → Plastic or wooden grids to increase heat transfer.
🔹 Drift Eliminators → Prevent water loss due to wind.
🔹 Fans & Louvers → Improve airflow for heat removal.
🔹 Basin & Piping → Collects cooled water for recirculation.

Cooling Tower Capacity Calculation
📌 Capacity (Tons) = (Water Flow Rate × Temperature Drop × 500) / 12,000
Where:
✔️ Water Flow Rate = GPM (Gallons per Minute)
✔️ Temperature Drop = (Hot Water Temp – Cooled Water Temp)
✔️ 500 = Water’s heat absorption rate
✔️ 12,000 = BTU per Ton of cooling
🔹 Example:
If Water Flow = 1000 GPM,
Temp Drop = 10°F,
Then Capacity = (1000 × 10 × 500) / 12,000 = 416.6 Tons

Cooling Tower Efficiency
📌 Efficiency (%) = (Cooling Range / (Cooling Range + Approach)) × 100
🔹 Cooling Range = Hot Water Temp – Cooled Water Temp
🔹 Approach = Cooled Water Temp – Wet Bulb Temp
✅ Example:
✔️ Hot Water = 95°F
✔️ Cooled Water = 85°F
✔️ Wet Bulb Temp = 78°F
✔️ Range = 95 – 85 = 10°F
✔️ Approach = 85 – 78 = 7°F
✔️ Efficiency = (10 / (10 + 7)) × 100 = 58.8%

Advantages & Disadvantages of Cooling Towers
✅ Advantages
- ✔️ Removes excess heat efficiently 🔥
  ✔️ Saves energy compared to air-cooled systems ⚡
  ✔️ Extends equipment lifespan 🏭
  ✔️ Low operating cost 💰
❌ Disadvantages
- ❌ Water loss due to evaporation 💦
  ❌ Requires chemical treatment (scaling & corrosion) ⚠️
  ❌ Large footprint for natural draft towers 📏