Cooling tower Performance – Summer Vs Winter
| Aspect | Summer Performance | Winter Performance |
| Cooling Capacity | Reduced, struggles to meet load | Excellent, can exceed design capacity |
| Driving Force (ΔT) | Small | Very Large |
| Approach | Wide (larger difference from WBT) | Narrow (can get very close to WBT) |
| Fan Operation | Max speed, continuous operation | Cycled, low speed, or off to prevent over-cooling |
| Water Consumption | Highest | Lower |
| Primary Challenge | Achieving sufficient cooling | Preventing freeze damage |
| Process Impact | Chiller/process may run less efficiently | Risk of water being too cold for the process |
The Real-World Implication: Control is Everything The massive performance swing means a cooling tower cannot be a “set it and forget it” system. Modern towers use sophisticated controls that automatically adjust based on the
load and, most importantly, the ambient wet-bulb temperature.
- A controller constantly measures the outlet water temperature.
- It compares this to a setpoint.
- In summer, it commands the fans to speed up to increase cooling.
- In winter, it commands the fans to slow down or cycle off to reduce cooling and, crucially, to activate freeze protection sequences.
In essence, a cooling tower is fighting to reject heat in the summer and fighting to avoid rejecting too much heat in the winter.