Comparative study of cooling tower fills: experimental analysis and CFD simulation of an alternative fill

• Published in: Journal of the Brazilian Society of Mechanical Sciences and Engineering 2024-07, Vol.46 (7), Article 412
• Main Authors: Araujo, S. D. O., Lages, A. S., Dutra, J. C. C., Primo, A. R. M., Michalewicz, J. S., Da Costa, J. A. P., Ochoa, A. A. V., Tomás, A. C. C., Alcântara, S. C. S.
• Format: Article
• Language: English
• Subjects: Air flow; Climate; Comparative studies; Cooling; Cooling towers; Energy efficiency; Engineering; Heat; Heat transfer; Mass transfer; Mathematical analysis; Mechanical Engineering; Numerical models; Parameter identification; Performance evaluation; Polyethylene terephthalate; Sensitivity analysis; Shear stress; Technical Paper; Turbulence models; Water flow; Water temperature; Water vapor
• ISSN: 1678-5878; 1806-3691
• DOI: 10.1007/s40430-024-04990-z

A novel numerical and experimental analysis was conducted to assess the energy efficiency of alternative fill materials in small cooling towers under tropical climate conditions. The study encompassed two main objectives: first, experimental validation through the manufacturing, construction, and testing alternative fill prototypes in a small cooling tower, evaluating their energy performance under varying air and water flow conditions at inlet temperatures of 34 °C, 37 °C, and 40 °C. The second aspect involved the computational simulation of heat and mass transfer phenomena using the Euler–Lagrange technique for biphasic flow and turbulent airflow modeled using the SST (shear stress transport) turbulence model and heat and mass transfer between air and water calculated via the liquid evaporation model. The parameters identified in the study include temperatures at the cooled water and air outlets, mass fraction of water vapor, and absolute humidity at the outlet. The numerical model was validated against experimental data, followed by a detailed sensitivity analysis of thermal and hydraulic performance comparing alternative and conventional industrial fill materials. The study's main contribution lays in evaluating the energy efficiency and feasibility of utilizing PET bottlenecks for constructing cooling tower fills in the specific climate conditions of northeastern Brazil. Results indicated a 5.0% difference in cooling efficiency between the fill materials, with industrial fill demonstrating approximately 1.25% higher heat and mass transfer coefficients than fill with bottlenecks. Ultimately, the study concluded that utilizing PET bottlenecks in a criss-cross arrangement presents a promising alternative in terms of efficiency, maintaining a temperature difference of less than 1 °C compared to industrial fill at inlet water temperatures up to 8.0 °C. This research contributes to advancing knowledge in cooling tower technology, particularly in material innovation, numerical modeling techniques, and environmental sustainability. The data indicate a tendency to replace polypropylene (PP), frequently used in industrial fillers, with polyethylene terephthalate (PET), a widely consumed recyclable material, resulting in significant environmental damage.