How critical is geometrical confinement? Analysis of spatially and temporally resolved particulate matter removal with an electrostatic precipitator.

This study investigates the spatial and temporal dispersion of particulate matter (PM) when using a needle-type electrostatic precipitator (ESP). The ESP is installed in tubes of 3 and 10 cm diameter. A simple light scattering setup integrated with image processing is built to evaluate and quantify the spatial and temporal dispersion of PM. The ESP is operated under stationary and continuous flowing modes to test its PM removal capability. Under the stationary mode, PM is removed efficiently in 10 and 45 seconds when using a 3 and 10 cm tube, respectively. In a more geometrically confined system, a large spatial particulate concentration gradient is seen from 18 to 24 cm, indicating that the cleaning capability can be controlled within a localized space. By modulating the applied voltage from direct current (DC) to a low-frequency pulse with 50% duty, the ozone concentration can be reduced by nearly 50% while maintaining the cleaning efficiency. The analysis with spatially and temporally resolved particulate dispersion provides a novel strategy for testing the performance of an ESP. Furthermore, physical confinement enhances both the spatial and temporal removal efficiency, which is crucial for indoor and personal air cleaning devices. These results will contribute to air purification and environmental monitoring.