Comparison of Diffusion Characteristics of Aerosol Particles in Different Ventilated Rooms by Numerical Method

Particle diffusion with gravitational sedimentation in displacement and mixing ventilated rooms is investigated numerically. The drift flux model, which considers the settling of particles under the effect of gravitational sedimentation, is adopted to simulate particle diffusion, while the simplified
model for solving the continuous fluid flow is combined. Since the PM 2.5 and PM 10 particles are mostly concerned in indoor environment, passive contaminant and 2.5-20 micron particles are investigated in this paper. The numerical results show that in a mixing ventilated room, the
distribution of nonpassive particles does not differ much from that of passive contaminant when the particle diameter is less than 20 microns. Meanwhile, in the displacement ventilated room, the gravitational settling should be taken into account when particle diameter is larger than 10 microns.
Comparison also demonstrates that displacement ventilation will bring particle contaminants generated by mannequins to the working zone and upper part of the room; in contrast, mixing ventilation will carry up the pollutant in a relatively small amount.