壁面材質對室內環境中空氣負離子控制懸浮微粒影響之研究

Abstract

懸浮微粒為室內空氣主要污染物之一，而其控制技術一般可分為過濾去除與靜電收集兩類。本研究的目的為評估室內材質表面特性對於空氣負離子(Negative Air Ion, NAI)控制懸浮微粒效率之影響。 NAI為一種帶有電荷，無污染性的物質，本研究利用針尖放電的原理來產生實驗所需的空氣負離子，分別產生5×103 ~ 1.0×104 ions/cm3、2×105 ~ 4×105 ions/cm3 、8×105 ~ 1.0×106 ions/cm3三種不同濃度範圍之空氣負離子。本研究以氯化鈉為氣膠物種，選取30 nm與300 nm二種粒徑分別注入不銹鋼製成的環境模擬箱中進行實驗，再選取三種常見的室內表面材質(壁紙、木材材質、水泥漆材質)貼附於模擬箱內壁進行室內環境模擬，探討表面粗糙度和介電常數以及材質表面電阻對有效清淨速率ECR (effective cleaning rate)之影響。 控制效率ka部分，在換氣率1.0/h下，關閉NAI實驗時，300 nm微粒以木材材質控制效率最佳(54.80%)，壁紙材質效率最差(45.34%);而30 nm微粒也是木材材質控制效率最佳(65.19%)，壁紙材質效率最差(52.89%)。開啟NAI實驗時，300 nm微粒以木材材質控制效率較佳(85.58%)，其次為水泥漆材質(84.62%)，壁紙材質最差(75.62%); 而30 nm微粒也以木材材質控制效率較佳(91.51%)，其次為水泥漆材質(88.02%)，壁紙材質最差(82.53%)。本實驗也證實300 nm與30 nm微粒之控制效率會隨著NAI之增加而變好。 在有效清淨速率ECR部分，300 nm微粒在換氣率1/h下之ECR分別為壁紙材質(26.90 Lpm)、木材材質(38.09 Lpm)、水泥漆材質(37.96 Lpm)；而30 nm微粒在換氣率1/h下之ECR分別為壁紙材質(33.08 Lpm)、木材材質(47.02 Lpm)、水泥漆材質(40.01 Lpm)。由此可得知，空氣負離子對30 nm微粒的控制效率大於300 nm微粒。 在壁面材質表面粗糙度方面，三種壁面材質之平均表面粗糙度(μm)分別為壁紙材質(0.32 ~ 0.40)、木材材質(2.61 ~ N.D)、水泥漆材質(2.12 ~ 2.34)，ECR似乎有隨著表面粗糙度增加而增加的趨勢。在壁面材質介電常數方面，三種壁面材質之介電常數分別為壁紙材質(1.91~1.93)、木材材質(2.89~2.92)、水泥漆材質(2.78~2.80) 。ECR值似乎會隨著材質介電常數增加而增加。在壁面材質電阻率測試中，木材材質與水泥漆材質之電阻率皆大於109 (Ω．cm)，壁紙材質之電阻率為4.6×104 (Ω．cm)。ECR似乎也會隨著表面電阻率增加而增加。

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). In 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. The 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. With 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. As 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.