Efficiently remove submicron particles by a novel foldable electrostatically assisted air coarse filter

Abstract

Electrostatic assisted air (EAA) coarse filters combine the benefits of electrostatic precipitators and fibrous filters, achieving high filtration efficiency for submicron particulate matters (PM), low pressure drop, and large dust-holding capacity. For application in heating, ventilation, and air conditioning (HVAC) systems, PM removal technology is required to work at high air duct velocity, for example, 1 to 3 m/s. However, both theory and experience have revealed that the pressure drop will increase at large airflow rates. Here, we developed a novel foldable EAA coarse filter by shaping the polarizing electrodes into a zigzag structure and folding the coarse filter between the electrodes. High filtration efficiency for submicron PM (85.0–94.0% for 0.3–0.5 µm PM, 92.0–96.5% for 0.5–1 µm PM) and low pressure drop (5.9–26.4 Pa) at high air duct velocity (1–3 m/s) are achieved by optimizing folding angle (θ) to 45°. We found that θ determines the shape of the PET fold and the nature of electric field, leading to different filtration performances. In order to get the module with better applicability, the optimum θ was determined simultaneously by both filtering velocity and effective polarizing area. The results are expected to facilitate the wide application of EAA coarse filters in HVAC systems for a healthy and energy-saving indoor environment.