CFD Assessment of Age-of-Air Distribution and Air-Change Effectiveness in a Detention Facility

Mechanical Engineering Department, FEU Institute of Technology, Sampaloc, Manila, 1015, Philippines

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Abstract

Overcrowded detention cells often suffer from inadequate ventilation, posing significant health risks to inmates due to the buildup of airborne contaminants. To improve indoor air quality and comfort in such confined environments, this study investigates the influence of different supply air configurations on the age-of-air (AoA) distribution and air-change effectiveness (ACE) in detention cells of a city jail in the Philippines. Computational Fluid Dynamics (CFD) simulations using the standard k–ε turbulence model with scalable wall functions were conducted to evaluate four ventilation setups varying in the number of ducting lines and air supply grilles. CFD serves as a powerful and non-intrusive tool for analyzing ventilation systems, particularly in environments where physical testing is impractical or unsafe. Results show that configurations with three ducting lines provide more uniform airflow distribution across bunk levels, while increasing the number of supply air grilles decreases the average AoA and enhances ACE. Among the four setups, the configuration with three ducting lines and ten supply air grilles per duct achieved the most balanced performance in terms of airflow comfort and ventilation efficiency. The findings highlight the potential of CFD-assisted design optimization in improving air quality management in detention facilities and other densely occupied confined spaces.