Comprehensive Environmental Assessment for Cooling Towers with Various Controls

Cooling towers are generally used in water-cooled chiller systems, which provide cooling energy for commercial buildings. This article assesses how the various control systems of cooling towers influence plume emissions and the electricity and water consumption of a chilled water system. Integrated with real control of cooling tower fans, chiller and cooling tower models were developed to analyze how the energy performance of a chiller and the water loss rate varied under different operating conditions. The status of air flows through the cooling tower was investigated to judge plume formation under various cooling tower controls. A simulation analysis on a chilled water system serving an office building showed that optimizing the fan speed control of cooling towers enables the annual electricity and water consumption costs to save 4.6% while also reducing the plume generation. The optimum control means adjusting the temperature of cooling water leaving the cooling tower in response to the chiller load and wet bulb outdoor temperature. The results of this article provide important insights into how to enhance the environmental performance of cooling towers for use in water-cooled chiller systems.