Particle deposition in indoor environments: analysis of influencing factors.

In this paper, several factors influencing particle deposition in indoor environments are analyzed with an analytical model and a three-dimensional drift flux model combined with the particle deposition boundary conditions for wall surfaces. The influences of flow conditions near the wall surfaces, surface roughness and particle concentration distribution on particle deposition indoors are studied. By modeling particle deposition onto surfaces with the analytical model, it is found that larger friction velocity near the wall surfaces and rougher surface may lead to larger particle deposition velocity when the particle size is small, but when particle size is large enough (the range is up to the actual friction velocity and in this study it is about 1-5 microm), the influence of the friction velocity and roughness could be neglected. Furthermore, the three-dimensional numerical simulations indicate that particle concentration distribution may be very different even for the same particle source and air change rate, which cause a different deposited particle flux. As the particle concentration distribution may not be uniform in most cases, especially for the ventilated rooms, it is important to incorporate particle concentration distribution when analyzing particle deposition in indoor environments. Some suggestions or rules for particle deposition controlling are also presented based on the analysis.