The properties of the needle-ring shaped DC ion airflow generator

A DC ion airflow generator with needle-ring electrode arrangement has been investigated for use in electrostatic elimination systems. The experimental results show that the amount of drawing-off ion airflow I ₂ and the drawing-off efficiency η can be greatly increased by connecting an inducing resistor in series with the inducing ring, and they reach saturation values as the resistance increases. While the hole diameter of the inducing ring is 3.0 mm, the needle-ring distance zero, the total corona current 25.0 μA and the air flow rate 7.0 m³/h, I₂ and η can be increased from 1.0 μA and 4% to saturation values of 4.75 μA and 19% respectively, with the resistance increasing from zero to 150 MΩ and over. I₂ and η can also be increased with the airflow rate, and reduced with needle-ring distance and the hole diameter of the inducing ring. With an inducing resistance of 200 MΩ, hole diameter of 1.5 mm, needle-ring distance of zero, air flow rate of 5.6 m³/h and corona voltage of -15.0 kV, I₂ and η grow to 17.4 μA and 30% respectively. When corona voltage and corona current are increased, I₂ is increased, but η is reduced. These results are valuable to the design and performance improvement of DC ion airflow electrostatic eliminators, electrostatic spraying and coating guns and negatively ionized air generators