Evaporation Rate from Heat Load (Method 1)

Calculates evaporation in lb/hr from the heat rejected, assuming all heat rejection occurs through evaporation. Uses the rounded latent heat of 1,000 BTU/lb for field calculations.

$$E_{\text{lb/hr}}=\frac{Q}{h_{fg}}$$

Variables

Symbol	Meaning	Unit
E	Evaporation rate	lb/hr
Q	Heat load	BTU/hr
$h_{f}g$	Latent heat of vaporization (about 1,000 BTU/lb in cooling towers)	BTU/lb

Worked example

For Q = 6,000,000 BTU/hr: E = 6,000,000 / 1,000 = 6,000 lb/hr. Converting to gpm: E = 6,000 / (8.34 x 60) = 12.0 gpm.

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Part of The Blueprint of Water