Drift Explained: Understanding Water Loss in Cooling Towers

For HVAC professionals, understanding the dynamics of cooling towers is critical for optimizing performance and sustainability. One crucial aspect that often gets overlooked is drift—the water lost from a cooling tower as liquid droplets entrained in the exhaust air. This phenomenon plays a significant role in the overall efficiency and environmental impact of cooling tower operations.

What is Drift?

Drift is defined as the water that escapes from a cooling tower in the form of tiny droplets carried away by the exhaust air. This loss is independent of the water lost through evaporation, which is a common consideration when calculating water usage in cooling operations. Drift loss can be quantified in terms of weight, typically measured in lbs/hr, or as a percentage of the circulating water flow.

Why is Drift Important?

Understanding drift is vital for several reasons:

• Water Conservation: Excessive drift results in significant water loss, which is crucial in water-scarce regions. Minimizing drift helps conserve precious water resources.
• Chemical Loss: The water carried away by drift droplets may contain chemicals, such as biocides or water treatment additives, diminishing their effectiveness and increasing operating costs.
• Environmental Impact: Drift can lead to contamination of surrounding areas with water treatment chemicals, potentially harming local ecosystems and leading to regulatory concerns.

Controlling Drift with Drift Eliminators

One effective solution to control drift is the use of drift eliminators. These devices are designed to capture and condense the droplets, redirecting the water back into the cooling tower. Properly designed and maintained drift eliminators can significantly reduce drift loss, making cooling tower operations more efficient and environmentally friendly.

Conclusion

As HVAC professionals, it’s essential to include drift management in your cooling tower maintenance practices. By understanding the mechanics of drift and implementing effective solutions such as drift eliminators, you can enhance water conservation, reduce chemical loss, and minimize environmental impact. Staying informed about drift will ensure that your cooling tower operations are not only efficient but also sustainable.