Evaporative Cooling Towers are commonly used to dissipate heat from industrial process operations by cooling water through a combination of heat and mass transfer. An evaporative cooling tower can operate over a wide range of recirculating water rates, air velocity rates, and heat loads with variation in the approach of cold water to the ambient wetbulb air temperature. Designed to manage summer worst case ambient conditions, the actual long term water and/or energy usage is overestimated, increasingly so for locations which experience extremes in seasonal weather. For instance, some evaporative cooling systems managing a constant industrial heat load can cool over 50% by non-evaporative air-cooled heat transfer; during reduced ambient air temperatures. This paper presents a procedure for predicting long term water usage of a cooling system based on regional climactic data. The analysis focuses on industrial cooling systems consisting of wet towers that supply a common set of process loop heat exchangers, typically arranged in parallel; and will provide analysis for water or energy minimization. The estimated water usage on a typical monthly, seasonal or annual basis is presented to demonstrate the energy –water tradeoff for sites across the continental United States. The results estimate how much operational flexibility is available for a cooling system and offers an understanding of the interaction between water and energy requirements under varying climate conditions.
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