A Dynamic Model for Performance and Efficiency of Evaporative Cooling Towers

Abstract

Abstract. Evaporative cooling towers are critical solutions to engineering design. Due to the complexity of the heat rejection mechanism and the commonality of the evaporative cooling application, there exists a significant opportunity for efficiency improvements. To mitigate the complexity issue, a model was developed that focuses on the quantification of benefits for efficiency projects. This tool can quantify the reductions in water usage, energy consumption, carbon dioxide emissions, and operational costs for industrial cooling towers for various projects using dynamic, hourly weather data inputs. A validation study using an industrial cooling tower was completed to compare the model and field data. The validation study completed by field data collection showed that the model's emphasis on simplicity does not negatively impact the accuracy of the model's outputs. A distinctive feature of this model is the ability to estimate the tower performance from design parameters and hourly weather conditions through various efficiency projects to the resulting energy, water, carbon dioxide emissions, and cost reductions. Since a cooling tower is a heat rejection device, the cooling capacity is a critical parameter for operation. This parameter was studied through the measured quantities for air discharge temperature, cooling tower fan power, and makeup water flowrate where the model predicts difference values with the field data of 4.3%, 4.7%, and 7.6%, respectively. Another parameter studied was the cooling efficiency, or approach, which the model predicts an average difference of 14% compared to the field data. This is a parameter that is highly dependent on physical design conditions for the cooling tower. Finally, the resultant parameters of the electrical and water consumptions were studied through the fan power and makeup water flowrate, respectively.