Cooling towers thermal performance

Effect of Maintenance on Cooling Tower Thermal Performance... 

Kroger, D. G. (2004) Air-cooled Heat Exchangers and Cooling Towers Thermal-flow Performance Evaluation and Design, Vol. 1 (PennWell). 

FIG. 12-22 Universal performance chart for natural-draft cooling towers. (Risk and Steel, ASCE Symposium on Thermal Power Plants, October 1958. )... 

Cooling towers fall under the general category of direct-contact equipment. In direct-contact equipment, fouling resistances are automatically eliminated because a surface is no longer available on which they can form. This is a unique feature because it allows direct-contact equipment to operate indefinitely without interruption in thermal performance. 

The principal design feature that permits economical application of the wet/dry tower is the summer damper component. This is a door-like air flow restrictor that is located in the heated dry air stream between the air-cooled heat exchanger and the fan. Its purpose is to reduce the air flow through the dry stream, while boosting the air flow in the wet stream, thereby enhancing the wet section thermal performance during summer operation. 

An important thermodynamic parameter in cooling tower calculations is the ratio of the thermal capacity of the water stream to that of the sir stream. This parameter is referred to as, the tower capacity factor. It is shown that when air or water efficiency, are plotted against the capacity factor test points for a given tower are found to lie on a single smooth curve. The correlation is obtained, irrespective of whether the equipment is used as a water cooler or air cooler, and irrespective of the temperature levels, temperature ranges and barometric pressures. The paper also shows that when a specified amount of heat has to be rejected into a specified air stream, optimum performance giving the lowest average water temperature is obtained when the water flow rate is chosen so that its thermal capacity is equal to the potential thermal capacity of the air stream. 13 refs, cited. 

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. 

The Influence of Temperature Stratification on the Thermal Performance of a Natural Draft, Dry Cooling Tower Buxmann, J. 

Typically limit to 2500 to 3500 ppm TDS maximum in the cooling system, depending on circumstances. High levels can increase the tendency for galvanic corrosion. Levels of over 5000 ppm TDS can affect thermal performance and may be detrimental to wood in alternatively wet/dry cooling tower zones, such as the fan deck and louver faces. 

J. R. Singham, The Thermal Performance of Natural Draft Cooling Towers, Imperial CoUege of Science and Technology, Department of Mechanical Engineering, London, 1967. 

Mechanical-draft cooling towers are the type most often found in the process industries. These provide their own air flow, and wind direction and velocity therefore do not greatly affect their thermal performance. They can be classified in several different ways ... 

Thermal performance of a cooling tower depends on a specific mass fiow rate of air through the fill (pounds of dry air per minute), whereas the fan does its job purely in terms of volume (cubic feet per minute). Since the specific voliune of air (cubic feet per pound) increases with temperature, it can be seen that a larger volume of air leaves the tower than enters it. The actual cfin handled by the fan is the product of mass fiow rate times the specific volume of dry edr corresponding to the temperature at which the air leaves the tower. This volumetric flow rate is the Q used in the following formulas, and it must be sufficient to produce the correct mass flow rate or the tower will be short of thermal capacity. 

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