A lottery draw machine-inspired movable air filter with high removal efficiency and low pressure drop at a high flow rate
A lottery draw machine-inspired novel movable air filter (MAF) system is presented in which MAFs are vigorously moved or rotated to generate a high electric field and capture particulate matter (PM) particles. The MAF system purified 500 mL of a hazardous level of PM particles (2016 μg m−3 PM10 and 1040 μg m−3 PM2.5) at a high flow rate of 2.5 m s−1 with high removal efficiencies (99.7% and 98.8% for PM10 and PM2.5, respectively) in 1 min. The MAF system also had a small pressure drop of 3–6 Pa, which was approximately an order or orders of magnitude lower than previously reported values, even at a high flow rate of an order of magnitude higher than previously reported values. The MAF system exhibited excellent recyclability of up to 300 cycles with high removal efficiencies (99.7–98% and 98.8–96.2% for PM10 and PM2.5, respectively). Furthermore, the MAF system could effectively remove 500 mL of PM particles at extremely high concentrations (over 10 000 μg m−3 PM10 and over 3000 μg m−3 PM2.5) with very high efficiencies (over 99.8% and 99.6%, respectively) and a very low pressure drop (6 Pa), and these properties led to the conversion to clean ambient air (24 μg m−3 PM10 and 12 μg m−3 PM2.5) in 15 min.