General operating diagram for a cooling tower

Note that Ntu is determined from process conditions imposed on the operation. It is not based on the performance of the tower itself. The water temperature unfortunately is not a simple function of Hvap0I, hence Equation 5.33 must be solved either numerically or via graphic solution. 

The area of the plot bound between the equilibrium curve (saturation curve) and the operating line represents the potential that drives the total 

Before applying our generalized equations to sizing cooling towers, we need to review some of the criteria for specifying operating conditions. The critical conditions that must be established before the design is initiated are the heat load, wet-bulb temperature, hot and cold water temperature and water rate. 

The determination of the heat to be dissipated by a cooling tower is an essential factor that not only affects the tower size, but also its effectiveness. If the heat load. determination is not accurate, either too high or too low, a larger or smaller size tower than is needed for a particular job could be selected. 

Dependable information has been developed for the heat rejector requirements of different types of power equipment air compressors, refrigeration equipment, steam condensers, diesel engines and natural gas engines. Table 5.1 gives information on the heat absorbed by cooling water for this type of power equipment. 

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Figure 5.7 General operating diagram for a cooling tower.

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