Cooling Towers

A.  With industrial cooling towers, cooling to 90% of the ambient air saturation level is possible.
B.  Relative tower size is dependent on the water temperature approach to the wet bulb temperature:
	Twater-Twb	Relative Size
	5	2,4
	15	1.0
	25	0,55
C.  Water circulation rates are generally 2-4 GPM/sq. ft (81-162 L/min m2) and air velocities are usually 5-7 ft/s (1.5-2.0 m/s)
D.   Countercurrent induced draft towers are the most common.  These towers are capable of cooling to within 2 °F (1.1 °C) of the wet bulb temperature.  A 5-10 °F (2.8-5.5 °C) approach is more common.
E.   Evaporation losses are about 1% by mass of the circulation rate for every 10 °F (5.5 °C) of cooling.  Drift losses are around 0.25% of the circulation rate.  A blowdown of about 3% of the circulation rate is needed to prevent salt and chemical treatment buildup.