Modeling particle dispersion and deposition in indoor environments

Area of Science:

• Environmental Engineering
• Indoor Air Quality
• Fluid Dynamics

Background:

• Particle dispersion and deposition significantly impact occupant health in enclosed spaces.
• Understanding indoor particle behavior is crucial for designing healthier built environments.

Purpose of the Study:

• To develop and validate a 3D drift-flux model for particle movement in indoor airflow.
• To investigate particle deposition rates and human exposure under different ventilation strategies.

Main Methods:

• A 3D drift-flux model coupled with Eulerian approaches was developed.
• A semi-empirical deposition model resolved size-dependent deposition characteristics.
• The model was validated against experimental data from scaled and full-scale chambers.

Main Results:

• A V-shaped deposition velocity curve was observed for particles from supply air, with minimum deposition at 0.1 µm.
• Ventilation type and air exchange rate had minimal effect on supermicron particle deposition.
• Submicron particles behaved like tracer gases; larger particles showed gravitational settling.
• Human exposure depended on occupant proximity to air outlets, with larger particles posing less risk.
• Displacement ventilation (DV) and under-floor air distribution (UFAD) showed concentration stratification for small particles, benefiting the occupied zone.

Conclusions:

• The validated drift-flux model provides accurate predictions of indoor particle behavior.
• Ventilation strategies like DV and UFAD can reduce human exposure to certain particle sizes.
• Particle size is a critical factor influencing deposition, settling, and human exposure indoors.