Performance evaluation of a miniature UV particle charger

A mini-UV aerosol charger was designed, and its charging performance was investigated in this work. The performance of a mini-UV aerosol charger was evaluated using DMA-classified silver (Ag) particles in the sizes ranging from 7 to 100 nm under varying exposure times and irradiation intensities. The intrinsic and extrinsic charging efficiencies, and charge distribution of test particles under different operational conditions were measured. It was found that the particle charging with 5 W UV lamps, emitting both wavelengths of 185 and 254 nm, achieved the optimal performance for the charger when operated at a flowrate of 0.3 LPM. The intrinsic and extrinsic charging efficiencies of sodium chloride (NaCl) and Di-Ethyl-Hexyl-Sebacat (DEHS) particles were also measured. The extrinsic charge distribution of test particles was lastly measured. This study further proposed the improvement of the photo-charging model based on the Fowler-Nordheim law (for the calculation of charge distribution of particles) by considering the field distribution of particle residence time in the charger.