Counterflow cooling tower performance

Figure 9-126A. eS F wet bulb 30°F range, counterflow cooling tower performance curves. Used by permission of Counterflow Cooling Tower Performance, The Pritchard Corp. (now, Black and Veatch Pritchard Corp.) (1957). 

Counterflow Cooling Tower Performance, J. F. Pritchard and Co. of California, Kansas City, Mo. (1957). 

Increases in loading, cooling range and humidity all tend to improve cooling tower performance. Two basic types of hyperbolic towers are counterflow and crossflow, as shown in Figure 4.12. 

Wrinkle, R. B. Chem. Eng. Progr., 67 (1971) 45. Performance of counterflow cooling tower ceils. 

In 1974 the Atlantic City Electric Co. placed Unit 3 of its B L England Station into commercial operation. Condenser cooling for the unit is provided by circulating sea water in a closed-cycle, natural-draft system. The cooling tower selected for the site was a hyperbolic, counterflow unit. The thermal test instrumentation procedures and test data as well as drift measurement results are given. The paper indicates that the tower operates within design specifications for thermal performance and that it meets the environmental criteria regarding the drift. 

Figure 12-8c shows the relationship of the hot water, cold water, and wet-bulb temperatures to the water concentration. From this, the minimum area required for a given performance of a well-designed counterflow induced-draft cooling tower can be obtained. Figure 12-Hd gives the horsepower per square foot of tower area required for a given performance. These curves do not apply to parallel or cross-flow cooling, since these processes are not so efficient as the counterflow process. Also, they do not apply when the approach to the cold water temperature is less than 2.8°C (5°F). These charts should be considered approximate and for preliminary estimates only. Since many factors not shown in the graphs must be included in the computation, the manufacturer should be consulted for final design recommendations.

Counterflow-induced draft towers, Figure 9.17(d), are the most commonly used in the process industries. Mechanical draft towers are capable of greater control than natural draft and in some cases can cool water to below a 5°F approach. The flow of air is quite uniform at a high velocity and the discharge is positive so that there is a minimum of backflow of humid air into the tower. The elevated fan location creates some noise and structural problems. It has been reported that mechanical draft towers at low water rates (19,800 gpm) perform better than natural draft towers. 

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