Development and experimental investigation of the narrow-gap coated electrostatic precipitator with a shield pre-charger for indoor air cleaning

We designed and evaluated a two-stage electrostatic precipitator with a shield pre-charger and a narrow precipitator for indoor air cleaning. Unlike the conventional ESP-type air cleaner, the ion generation and particle charging regions were separated by a perforated plate with bias voltage. The electrical energization was achieved by connecting a large resistor in series with the shield electrode. A narrow-gap plate-plate precipitator was placed after the pre-charger for a strong electric field and a high specific collection area. The performance of the shield pre-charger, the narrow precipitator and their integration in lab-scale of 62 m3/h and pilot-scale of 500 m3/h were evaluated. The overall collection efficiency was 98.6 % and 75.5 % for gas flow velocities of 0.4 m/s and 1.2 m/s, respectively. The ozone concentration was around 0.2 ppm for a 24 h continuous operation. Our study showed a close relationship between particle charging and shield voltage with charging current, and a relatively stable performance under high gas flow velocity. The particle collection efficiency was 2.5 times higher than that of a conventional ESP-type air cleaner of similar size at a gas velocity of 1.2 m/s.