Numerical Study of Particle Dispersion in Displacement Ventilated Rooms

A three-dimensional drift-flux model combined with the deposition boundary conditions for wall surfaces in ventilated rooms are presented to study the particle dispersion in displacement ventilation rooms. Three ventilating air flow rates, 2 ACH, 5 ACH, 8 ACH and several particle sizes, 1, 2.5, 5, 7.5, 10 micron, are investigated. The results show that the particle dispersion characteristics are very different in displacement ventilated rooms with different air supply volume. In rooms with the same air supply volume, large-diameter particles diffuse more widely than small ones. The concentration of large-diameter particles in the lowert part is higher than that of the upper part while that of the small-diameter particle is contrary. Small size particles diffuse in the whole ventilated room while large size particles diffuse to the upper part of the room when the air supply volume increase.