Unipolar Charging of Aerosol Particles in the Size Range of 75-500 nm by Needle-plate Corona Charger

摘要

A simple unipolar needle-plate corona charger (NPC) was designed, fabricated and tested on aerosol Al2O3 particles in the size range 75-500 nm. The intrinsic charging efficiency, particle electrostatic losses, and extrinsic charging efficiency were investigated depending on the corona current (35-215 μA), corona polarity, and aerosol flow rate (12-250 l/min). It was found that the intrinsic charging efficiency of the NPC is growing with increase in the corona current and the particle size and decrease in the aerosol flow rate. However, the extrinsic charging efficiency is lower than intrinsic one due to the particle electrostatic losses. Although the NPC has very simple design, it provides the extrinsic charging efficiency comparable with that of unipolar corona chargers of other types having more complicated design. The maximum value of the extrinsic charging efficiency was more than 40% for particles in the size range from 98 to 210 nm.