Electrostatically assisted air coarse filtration for energy efficient ambient particles removal: Long-term performance in real environment and influencing factors

Abstract

Electrostatically assisted air (EAA) coarse filter can improve the particle filtration performance of low efficiency filters without increasing their pressure drop. In this study, we investigated the long-term single pass filtration efficiency for 0.3–10 μm ambient particles, pressure drop, PM2.5 collecting amount, and energy consumption of an EAA coarse filter during a 51-day operation period. We found that the efficiency of EAA coarse filter varied with average values of 87.6%–97.1% for 0.3–10 μm particles, respectively, while the pressure drop increased from 14.6 Pa to 63.1 Pa at face air velocity of 1 m/s. Using K-means clustering and principal components analysis methods, we discovered that before 33 days, the significant influencing factors of the efficiency for 0.3–0.5 μm particles included air temperature, air moisture content, 3–10 μm particle number concentration, and PM2.5 collecting amount. While after 33 days, only PM2.5 mass collecting amount has a significant negative correlation with the efficiency for 0.3–0.5 μm particles. The efficiency became relatively unsteady and the PM2.5 collecting amount reached 131 g/m2 after 33 days. The total energy consumption of EAA coarse filter rose more slowly as PM2.5 collecting amount increased when compared with that of a conventional electret filter (KAFPO78A4, Daikin Inc., Japan). We suggest the high efficiency EAA coarse filtration as an energy efficient method for ambient particle removal in the view of its long-term performance.