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Improper HVAC design can facilitate airborne pathogen spread in indoor environments. This study investigates particle release from fibrous filters in a heat-based filter disinfection system, where upstream and downstream mechanical gates regulate airflow and isolate disinfection units during operation. Gate movement induces aerodynamic disturbances capable of dislodging trapped particles. Experimental and numerical analyses were conducted to evaluate the influence of gate rotation speed on flow dynamics and particle release. Experiments with shock, 2-second, and 10-second gate rotations quantified released particles by measuring filter weight differences before and after gate movements, while CFD simulations examined transient air velocity, acceleration, and turbulent kinetic energy (TKE) on the filter surface. Results showed that rapid gate movement significantly increases particle detachment. The gate motion with a shock caused about 5.9% release, whereas a 10-second rotation yielded 10 times lower particle release compared to the shock case. Simulations confirmed that longer gate durations minimize flow acceleration and TKE growth, indicating that abrupt transient flow changes promote particle release from loaded filters. • Gate movement can create vortices and increase turbulence in the disinfection unit. • Filter weight loss confirms particle release from the filters due to aerodynamic effects. • Gate movement with a shock released 5.9% of particles entrapped with the filter. • The 10-second gate rotation cuts turbulence growth by 78% versus the 2-second case. • Slower gate rotation lowers particle release by reducing flow disturbances.
Rasouli et al. (Mon,) studied this question.