Determining Proper Cooling Tower Size

Determining Proper Cooling Tower Size

To maximize the benefits of a water cooling tower, the appropriate tower size must be selected, requiring the identification of several critical factors. Cooling towers are a relatively inexpensive and reliable way of expelling heat from a number of industrial processes, including nuclear & thermal power plants, petroleum refineries, petrochemical plants, food processing plants. As the worldwide market for these applications continues to grow, so does the need to address the issue: How large should an industrial cooling tower be to efficiently handle a specific application. “There are a lot of different applications where you certainly don’t want an undersized cooling tower,” says Luke LIU, president of LATINO.“For example, if an undersized cooling tower is not producing cold enough water to cool the condenser loop of an office building’s HVAC chiller, then the chiller could shut down. That would probably mean some expensive repairs plus a lot of angry tenants.” On the industrial side, Luke advises that insufficient tower cooling capacity can cause breakdowns or even severe damage to costly process equipment, resulting in extensive losses in productivity. In fact, determining the minimum size for almost any application is critical. Cooling towers are known, generally, for their ability to expel “waste” heat from an industrial process or the condenser in a comfort-cooling application. Wet cooling towers achieve this function by evaporating a small portion of the recirculating water, resulting in significant cooling of the returning water to the process.

Cooling Tower Sizing

For most wet cooling tower applications, optimum cooling tower size may be determined by a combination of four different metrics: Heat Load, Range, Approach, and Wet Bulb Temperature. “When three of four sizing factors are held constant, the requirement for cooling tower size varies directly with Heat Load, but inversely with Range, Approach, and Wet Bulb Temperature,” Luke explains. “So, there can be several design decisions to make that will impact the ultimate size of the required cooling tower.”

Efficiency Matters

Luke adds that maintaining cooling tower efficiency is important to most applications. In many cooling towers, particularly the wet metal-clad models, cooling efficiency is compromised when necessary aggressive chemical treatments are limited due to the risk of damage to metal surfaces. Also, chemicals such as those used to rid water of biological growth can cause fouling buildup inside the tower, which reduces cooling efficiency. “This is one of the reasons why cooling towers composed of FRP plastic are becoming more popular,” Luke says. “With the FRP towers, you can treat the water more aggressively and don’t have to worry about corrosion problems at the tower.” Another efficiency-related advantage of FRP cooling towers is they are impervious to corrosion. The corrosives present in saltwater air or the caustic atmosphere of many industrial sites continuously attack metal-clad towers, making them less efficient and prone to maintenance and unscheduled shutdowns. Because FRP towers are unaffected by corrosives, they require little maintenance and provide a much longer service life. Latino for example, all have a 20-year warranty. Cooling tower efficiency can also be affected by tower footprint. “Some companies choose a tower with a smaller footprint to conserve on space,” Luke notes. “But that may require using more power to drive the tower, and energy savings is high on a lot of companies’ priorities. So, in those cases, a cooling tower with a bigger footprint may consume much less energy, and therefore would be the more efficient choice.” Luke adds that for most industrial and commercial applications, it is highly beneficial to consult with an experienced cooling tower engineer before finalizing plans to purchase a tower for a facility. Latino provides assistance in determining cooling tower size in a range of different tower designs through the web site: https://www.tianjinlatino.com/