Experimental and numerical study on particle distribution in a two-zone chamber.

Area of Science:

• Environmental Science
• Aerosol Science
• Indoor Air Quality

Background:

• Understanding aerosol dynamics is crucial for accurate personal exposure assessments in indoor environments.
• The limitations of the well-mixed model in exposure assessments are known, but research on discrepancies with models including gravitational effects is scarce.

Purpose of the Study:

• To develop and validate a new Eulerian-type drift-flux model for simulating particle dispersion and personal exposure in a two-zone environment.
• To compare exposure predictions from the new model with those from the traditional well-mixed model.

Main Methods:

• Developed a new Eulerian-type drift-flux model incorporating drift velocity from gravitational settling and diffusion.
• Validated the model using a small-scale chamber with airflow and particle concentration measurements via Phase Doppler Anemometry.
• Applied the validated model to a hypothetical two-zone scenario to compare exposure predictions.

Main Results:

• Simulated airflow and concentration profiles closely matched experimental results.
• Observed significant inhomogeneous concentration for 10 μm aerosols experimentally.
• The drift-flux model showed different transport and dispersion rates compared to the well-mixed model, especially for coarse particles.

Conclusions:

• The well-mixed model tends to overpredict concentrations in the source zone and underpredict in the exposed zone.
• The drift-flux model provides a more realistic assessment of personal exposure, particularly for coarse aerosols.
• The well-mixed assumption should be used cautiously for exposure assessments involving coarse particles due to potential inaccuracies.