The effect of wall surface materials on the control of suspended particulates by negative air ions
Date Issued
2009
Date
2009
Author(s)
Wang, Shou-Wen
Abstract
The suspended particulate is one of the major air pollutants in indoor environment. Generally, the removal methods of the suspended particulate can be classified to filtration and electrostatic collection technologies. The purpose of this work is to evaluate that under how the surface characteristics of indoor surface materials influence the removal efficiency of indoor suspended particulate with different concentration of Negative Air Ions (NAI).n this work, we used negative electric discharge to produce NAI (5×103 ~ 1.0×104 ions/cm3、2×105 ~ 4×105 ions/cm3、8×105 ~ 1.0×106 ions/cm3). Two sizes (30 nm and 300 nm) of NaCl were selected as the test aerosol to be input to the chamber which was manufactured form stainless steel to simulate indoor environment. We select three kinds of common indoor materials (wallpaper, wood and cement paint) to adhere to the surface of the wall inside the chamber, and investigate that how dielectric constant, surface roughness and surface resistance influence the ECR value.he experimental results showed that when the ventilation is 1.0/h, and the NAI was turned off, the 300 nm-particle control efficiency of the wood is highest(54.80%) and that of the wallpaper is lowest(45.34%). For 30 nm-particle, the control efficiency of wood is better(65.19%) than that of others, as well as that of the wallpaper is the lowest(52.89%). While the NAI was turned on, the 300 nm-particle control efficiency of the wood is largest(85.58%), and the second one is cement paint(84.62%), the wallpaper is smallest(75.62%). With 30 nm-particle, the control efficiency of the wood is highest(88.02%) and that of the wallpaper is lowest(59.6%). The experimental results showed that the control efficiency of 30 nm-particle and 300 nm-particle increased with the NAI concentration.ith regard to the ECR of 300 nm particle, ventilation is 1.0/h, the ECR of the wallpaper is 26.90 Lpm, wood is 38.09 Lpm, cement paint is 37.96 Lpm. For 30 nm particle, ventilation is 1.0/h, the ECR of the wallpaper is 33.08 Lpm, wood is 47.02 Lpm, cement paint is 40.01 Lpm. With regard to the particle diameter, the removal efficiency of 30 nm-particle is better than that of 300 nm-particle with the aid of NAI.s for texture surface roughness, we compare the three kinds indoor materials (wallpaper, wood and cement paint). Surface roughness(μm) for wallpaper is 0.32 ~ 0.40, 2.61 ~ N.D for wood, and 2.12 ~ 2.34 for cement paint. The ECR is higher when the texture surface roughness increases. As for material dielectric constant, dielectric is 1.91~1.93 for wallpaper, 2.89~2.92 for wood, and 2.78~2.80 for cement paint. The ECR is higher when the dielectric constant increases. As for material resistance, resistance is higher than 109 (Ω．cm) for wood and cement paint, 4.6×104 (Ω．cm) for wallpaper. The ECR is also higher when the resistance increases.
Subjects
suspended particulate
Negative air ion, ECR
texture surface roughness
dielectric constant
resistance
Type
thesis
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