Click here to enlarge imageEvaporative coolers are also used for adding capacity in “thermally challenged” plants. This allows for additional direct cooling without having to add tower capacity or buy additional makeup water.Water ConservationWith water supply restrictions and the price of clean water increasing, many believe that a dry, air-cooled unit is the only option. This, however, may not be the case.For water-limited applications, when not enough water is available for cooling the entire load, a hybrid unit incorporating a dry and wet section can be used (see Figure 3).In addition to materials and water quality, there are many factors considered in the design optimization of evaporative systems including pressure drop, fouling factors, noise, footprint and horsepower. There are tradeoffs between tube material and water quality and treatment (see Figure 4). Consequently, a water treatment professional should be part of the design process.ConclusionWater (resource) issues will continue to have an increased impact on plant design and operation. Closed-loop, evaporative coolers can help maintain plant performance while utilizing water streams that are currently unusable with conventional towers and heat exchangers. About the Author: Peter G. Demakos, P.E., is president of Niagara Blower Co., based in Buffalo, NY. This article is based on a presentation made to the 66th International Water Conference in Orlando, FL.