Equation 6.8 correlated mechanical-draft performance data

For one- or two-cell cooling towers the water flow is normally maintained, and to limit the fall in water temperature the air flowrate is controlled through the tower. The simplest method is an on/off control of the air fan by means of a thermostat with a sensing element in the water leaving the tower. Another relatively simple method of control is to use a two-speed motor together with a two-step thermostat to have high-speed or low-speed fan rpm, depending on the water temperature. [Pg.142]

Towers that operate in freezing weather required special consideration to provide dependable service and to prevent damage from freezing and ice accumulation. The most prevalent winter operating problem of water cooling towers is the formation of ice on the louvers to the extent of seriously, or even totally, restricting the air flow. [Pg.142]

under the most severe conditions, ice does accumulate on the louvers to a detrimental degree, operation of the fans in reverse will force warm air out through the louvers, melting the accumulated ice. Reverse operation of fans is used only to eliminate ice, not prevent it. Unfortunately, most fan drive units are not designed for continuous reverse operation. (See Chapter 9 for a discussion of ice prevention systems for cooling towers.) [Pg.143]

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