1. Definition & Working Principle
A Closed Circuit Cooling Tower is a heat rejection device that cools process fluids (water, oil, glycol, etc.) in a completely sealed loop, preventing contamination and minimizing water loss. It combines evaporative cooling and air convection for high efficiency.
How It Works:
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Hot fluid circulates through internally finned or smooth coils.
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Spray water is pumped over the coil exterior, forming a thin film.
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Airflow (induced by fans) evaporates the water film, absorbing heat.
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The cooled fluid returns to the system, while the unevaporated water recirculates.
2. Key Components
| Component | Function |
|---|---|
| Heat Exchanger Coil | Sealed tubes (stainless steel/copper) to transfer heat without fluid exposure. |
| Spray System | Nozzles distribute water evenly over coils for evaporative cooling. |
| Fan & Drives | Axial or centrifugal fans to force/pull air across the coil (up to 5 m/s). |
| Water Basin | Collects and recirculates spray water; includes filtration and bleed-off. |
| Drift Eliminator | Reduces water droplet carryover (drift loss ≤ 0.001%). |
3. Advantages vs Open Towers
| Feature | Closed-Circuit Tower | Open Cooling Tower |
|---|---|---|
| Fluid Protection | Zero contamination (closed loop). | Exposed to air/dust. |
| Water Savings | 30–50% less consumption (no evaporation loss). | High makeup water demand. |
| Energy Efficiency | Lower condensing temperatures (approach wet-bulb temp). | Less efficient. |
| Maintenance | Reduced scaling (clean fluid inside). | Frequent cleaning is required. |
4. Technical Specifications
| Parameter | Typical Range | Notes |
|---|---|---|
| Capacity | 10–2,000 RT (Refrigeration Tons) | 1 RT ≈ 3.5 kW cooling. |
| Flow Rate | 5–500 m³/h | Depends on ΔT (5–15°C typical). |
| Operating Pressure | 1.0–4.0 MPa | Higher for industrial systems. |
| Materials | Coils: 304/316SS, Copper, Titanium | Shell: Galvanized steel/FRP. |
| Fan Power | 1–100 kW (VFD options available). | Axial fans for low noise. |