Counterflow tower

These contain tiers of splash bars or decks to aid in the breakup of water drops to increase the total water surface and, subsequently, the evaporation rate. 

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Figure 12-12 illustrates water and air relationships and the driving potential which exist in a counterflow tower, where air flows parallel but opposite in direction to water flow. An understanding of this diagram is important in visualizing the cooling-tower process. 

Figure 9. Compares cross flow and counterflow towers.

System designers often think dampers bloek airflow and are suitable to prevent baek drafts in idle towers. This is not the ease. Airfoil dampers simply hamper fan housing efficiency- they do not block airflow. Air Inlet Screens are always part of blow through, counterflow towers to protect people from rotating equipment. Some designs can be a hazard when accessible from the underside and require the specifier to call out additional screening. They can be a worthwhile accessory when there are nearby trees even when not required for safety reasons. Air inlet screens should be eliminated on towers utilizing inlet ductwork. Inlet ductwork may also make it necessary to block extraneous air entry such as from the underside when towers are elevated. 

Distribution System Mechanical method of passing hot water over the fill uniformly. Low-pressure spray-through piping and nozzles are usually used in counterflow towers gravity drop is normally utilized in crossflow towers. 

In the spray-type distribution system, normally employed for counterflow towers, a main header carries water to spray trees containing a battery of nozzles. The nozzles are sized and arranged to provide an even distribution of water over the fill. 

SPRAY-TYPE DISTRIBUTION SYSTEM FOR COUNTERFLOW TOWER... 

Crossflow mechanical draft towers are thermally less efficient. They offer less resistance to air flow and can operate at higher velocities than counterflow towers, which means less horsepower and smaller cell sizes for comparable outputs. In practice, however, both crossflcw and counterflow designs have advantages and limitations, depending on the type of application. 

Thus, both cross- and counterflow towers have the same minimum coefficient at an L G ratio of zero and both increase to infinity at (L G)max. A... 

A low air rate requires a large tower, while a high air rate in a smaller tower requires greater fan power. Limitations in air velocities are typically 300-500 fpm in counterflow towers, and 350-650 fpm in crossflow towers. 

The paper considers the state-of-the-art in cooling towers, covering various types of towers in use. It discusses how they respond to the present and the future needs of the industry. A trend toward the counterflow design in the heat exchanger is indicated, and a forced draft counterflow tower is described. The design of the fan-assisted tower using both mechanical and natural draft is briefly dealt with. 1 ref. cited. 

Fig. 1.3 (a) Natural draft, hyperbolic, counterflow tower (b) Natural draft, hyperbolic crossflow tower (c) Induced draft, crossflow tower (d) Induced draft, counterflow tower (e) Forced draft, galvanized, evaporative condenser (f) Induced draft, FRP, bottle tower. 

In crossflow towers, the plenum area occupies the center of the tower, usually in a V shape, from the base of the tower to the fan. In counterflow towers, the plenum area occupies the entire top third plan area of the tower. 

Counterflow, as would be expected, allows more efficient transfer of heat and mass. With the application of a modem high-efficiency fill, the counterflow tower has become the most effective and most compact type of unit [11]. It is less open in its constmction than the crossflow type. This reduces the penetration of sunlight and the rate of growth of... 

Counterflow tower One in which air, drawn in through the air intakes (induced draft) or forced in at the base by the fan (forced draft), flows upward through the fill material and interfaces conntercnrrently with the falling hot water. 

Partitions. Towers consisting of two or more cells shall have a solid transverse partition wall between all cells which extends from louver face to louver face and from basin-curb level to fan-deck (counterflow towers) and distribution-deck lev-... 

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