Investigation of electrostatic forces on particle deposition in a test chamber

Particle deposition under the influence of an electrostatic force is very common but is usually ignored as a factor in many indoor environments and controlled chamber studies. A new model accounting for Brownian and turbulent diffusion, inertia effect, Coulombic (field) and image forces has been formulated. Electrostatic-enhanced deposition velocity was quantitatively investigated and compared with the experimental results. An experimental test chamber facility of 1.8 m(3) was designed to study particle deposition under the influences of electrostatic forces using monodisperse tracer particles in the size range of 3.5-9.0 mu m. The test sample surfaces were acetate sheet, plain smooth glass plate and thin copper coil. In another set of experiments, the surfaces were treated with commercial anti-electrostatic spray. The results reveal that deposition velocity onto the acetate sheet is significantly higher than that onto the plain glass and copper surfaces showing that the electrostatic attraction force must be taken into account. The key mechanism for deposition onto acetate sheet is by electrostatic attraction. Deposition onto the acetate sheet pre-treated with an anti-static spray shows deposition significantly reduced by 93%. The results also shows that glass surfaces should be first pre-treated to reduce static before deposition velocity measurements. By treating the glass surface with the spray, the deposition velocity was reduced by 68%. A similar reduction was observed for copper foil samples.