Effects of roughness, dielectric constant and electrical resistivity of wall on deposition of submicron particles driven by ionic air purifier

Abstract

The surface characteristics of wall play an important role in the deposition rate of submicron aerosol particles (SAPs) in a room. However, the effects of wall characteristics, including surface roughness (SR), dielectric constant (DC) and electrical resistivity (ER), on the deposition of SAPs driven by the ionic air purifier (IAP) is still unclear, and this study aims to investigate this important issue.The experiments were conducted in a stainless steel chamber equipped with an IAP. The surfaces of chamber wall were covered by six different wall materials for testing. In the experiments, the NaCl(s) monodisperse SAPs in the range of 50 to 300nm (50, 80, 100, 200 and 300nm) were introduced into the chamber, and then the decay of particle number concentration was monitored continuously. The effects of wall surface characteristics on the performance of IAP is analyzed by mixed model to recognize the effectiveness of each parameter.SR of the wall is the key parameter response for the IAP performance on the deposition of SAPs. SR may diminish the thickness of particle-concentration boundary layer and change the air flow pattern near the walls and is hence beneficial to the IAP performance. Besides, SRof the test wall materials is negatively correlated to the DC, and the effect of SR may overwhelm the effect of DC. Hence, these two effects are highly correlated. Additionally, when the IAP is operating, the “back corona” develops more likely on the materials with higher ER. The back corona significantly reduces the IAP performance.