Comparison with Open (Direct-Contact) Towers
| Parameter | Closed-Circuit (Indirect) Tower | Open (Direct-Contact) Tower |
| Process Fluid | Isolated in sealed coils | Exposed directly to air |
| Heat Transfer | Fluid → Coil → Water Film → Air (Indirect) | Water → Air (Direct Contact) |
| Water Treatment | Only for small spray loop | Required for entire system volume |
| Freeze Risk | Very low (primary loop protected) | High (exposed water in basin/lines) |
| Contamination Risk | Negligible for process fluid | High (airborne debris, microbes) |
| Approach to WBT | Larger (8-15°F typical) | Smaller (5-10°F typical) |
| Maintenance Focus | Coil cleaning, spray nozzles | Fill cleaning, basin, water chemistry |
| Installation Cost | Higher (up to 2-3x) | Lower |
Common Applications
Closed-circuit towers are specified when process fluid integrity is paramount:
- Critical Industrial Processes:
- Laser cooling water
- Injection molding machines
- Chemical process cooling
- Food & beverage production
- Pharmaceutical manufacturing
- Sensitive HVAC/Mechanical Systems:
- Chiller condenser loops where water treatment is problematic
- Glycol-cooled systems
- Heat pump source/sink loops
- High-Tech Facilities:
- Data center cooling (chip-level water cooling)
- Medical equipment cooling (MRI machines)
- Laboratory equipment
- Water-Scarce/Problematic Areas:
- Where makeup water quality is poor (high solids, silica)
- Where water conservation is critical (lower evaporation than open towers)