Effects of wall materials and particulate size on the removal of indoor particulates by negative air ions
Date Issued
2011
Date
2011
Author(s)
Peng, Chang-Jhe
Abstract
Suspended particulates are major indoor air pollutants. The purpose of this study was to evaluate the effect of aerosol particle size and wall surface characteristics of materials in indoor environment on the control of aerosol particles by the negative air ions. In this study, the aerosol particles where composed of NaCl in the range of 30 nm to 300 nm (30 nm, 50 nm, 80 nm, 100 nm, 200 nm, 300 nm) and were injected into an experimental chamber of stainless steel. Then the experimental chamber wall surface were covered by six species of common decorating materials panel (two wood materials, two paint materials, two wallpaper material). This study investigated the removal efficiency, and ECR value (effective cleaning rate) for quantitative assessment. Diffusion increases as particle size reduction
The removal efficiency was found the highest at 50 nm. Diffusion of particle decrease with particle size, electric charges increases with partice size. Electric field-induced mechanism is more significant for larger particle. At 50 nm the two mechanisms works strongly. As for the wall surface materials, in case of 50 nm, the control efficiency of wall paper is better (76.44%) than that of others, as well as that of the paint material is the lowest (70.92%) in this study. In case of 300 nm, the control efficiency of wood materials is better (53.74%) than that of others, as well as that of the paint material is the lowest (49.23%) in this study.
When particle size is small, the diffusion mechanism is more significant. Surface roughness significantly has obvious impact on the ECR. The wall paper has highest surface roughness in this study .In the case of 50nm, the ECR of the wallpaper is higher (26.90 Lpm) than that of others. When particle size is larger, the electric field-induced mechanism is more significant. Dielectric constant and surface resistivity have obvious impact on the ECR. The walnut wood materials have highest Dielectric constant and surface resistivity in this study. In the case of 50nm, the ECR of the walnut wood is higher (5.5Lpm) than that of others.
Subjects
suspended particulates
diameter of particle
negative air ion
ECR
surface roughness
dielectric constant
resistance
Type
thesis
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