Cooling Towers

Cooling towers are defined as any open water recirculation device that uses fans or natural draft to draw or force air to contact and cool water by evaporation. When one thinks of cooling towers, the hyperbolic towers associated with nuclear power plants probably come to mind.  While these cooling towers are an extreme case in terms of size, they are exactly the types of apparatus being described.  These and other smaller towers are used widely in industrial applications.

Cooling towers may use a number of different techniques to draw (draft) air into the system as a coolant.  The three most common draft types are forced draft, induced draft, and natural draft.  Forced draft cooling towers have a fan, or collection of fans, located at the bottom of the tower. The fans are used to push air up through stack.  By contrast, induced draft cooling towers have the fans in the top of the stack to pull air upwards. Natural draft cooling towers use natural convective airflow moving up the stack to cool the water. These systems are very large, very expensive and used mostly by power utility companies.

In addition to their drafting method, cooling towers are differentiated by their functional designs, which describe how water and air are mixed to cool down the system.  The four main types of cooling tower designs are cross flow, counter flow, closed loop, and open loop systems.  Cross flow design mixes air and water at a 90-degree angle. The advantages of this design include low pressure drop and low power consumption. Counter flow design mixes air and water in a vertical flow method where the water is falling and the air is rising. The advantage of this design is a smaller footprint. A closed loop system works similarly to a refrigeration system. The cooling water is contained inside a closed piping system and evaporative cooling occurs by running water over the pipe containing the heated water. An open loop system pumps the heated water into a tank at the top of the tower. The water cascades down through a series of louvers or plates in the system while cooling air is moving upwards. The evaporative effect removes heat from the water that is then recirculated back into the process.

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Part Numbers for Cooling Towers