Submicrometer particle removal indoors by a novel electrostatic precipitator with high clean air delivery rate, low ozone emissions, and carbon fiber ionizer.

A novel positive-polarity electrostatic precipitator ( ESP) was developed using an ionization stage (0.4 × 0.4 × 0.14 m3) with 16 carbon fiber ionizers in each channel and a collection stage (0.4 × 0.4 × 0.21 m3) with parallel metallic plates. The single-pass collection efficiency and clean air delivery rate ( CADR) were measured by standard tests using KCl particles in 0.25-0.35 μm. Performance was determined using the Deutsch equation and established diffusion and field charging theories and also compared with the commercialized HEPA filter-type air cleaner. Experimental results showed that the single-pass collection efficiency of the ESP ranged from 50 to 95% and decreased with the flow rate (10-20 m3/min), but increased with the voltage applied to the ionizers (6 to 8 kV) and collection plates (−5 to −7 kV). The ESP with 18 m3/min achieved a CADR of 12.1 m3/min with a voltage of 8 kV applied to the ionization stage and with a voltage of −6 kV applied to the collection stage. The concentration of ozone in the test chamber (30.4 m3), a maximum value of 5.4 ppb over 12 h of continuous operation, was much lower than the current indoor regulation (50 ppb). [ABSTRACT FROM AUTHOR]