Cooling Tower Rule of Thumb

Definition

A practical relationship stating that evaporating about 1% of the recirculating water lowers the bulk water temperature by roughly 10 degrees F.

It emerges directly from latent heat, since evaporating 1% of a 1,000 gpm flow removes about 81,000 BTU per minute, which cools the remaining bulk by about 9.8 degrees F. The calculation shows latent heat doing the heavy lifting for cooling. It is a memorable shortcut for estimating cooling tower performance and water loss.

Related concepts

Evaporative Cooling · Latent Heat of Vaporization · Heat Load

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Part of The Blueprint of Water · 🛠️ operations