Countercurrent cooling tower rating chart for 15 range

The lowest possible temperature that water can be cooled to in a cooling tower is the wet-bulb temperature of the air. However, this should not be viewed as a practical temperature limit as the vapor pressure out of the water and in the air is the same when the water reaches the wet-bulb temperature, a 

A common fallacy arises that cooling towers cannot function when the inlet air is at its wet-bulb temperature. To the contrary, when air at the wet-bulb temperature enters the tower it acquires sensible heat from the hot water, thereby raising its temperature so that it is no longer saturated. Consequently, water evaporates continuously into the air phase as it ascends through the tower and cooling takes place. 

Staging is a technique used for overcoming small L G ratios. Staging in effect involves the use of two or more towers in series. Water introduced to the top of the first tower is hot and first contacts air of enthalpy, H2, along 

Elevation can also play a role, for at reduced atmospheric pressure the saturation curve will be higher. This causes an increase in the potential and 

In the first design, a small L G ratio must be used. Since G cannot be increased beyond certain limitations (because of economics), L should be small. Experiments on cooling towers have indicated that their characteristics break sharply when L approaches a critical point varying with design. The 

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Figure 6.4 Countercurrent cooling tower rating chart for 15° range. McDowell [ 1 ] provides a family of charts for different ranges.

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