Evaluation of the Performance in Charging Efficiencies and Losses of Ultrafine Particles Ranging in Sizes from 15 to 75 nm in a Unipolar Corona-based Ionizer

Abstract For this study, a unipolar corona-based ionizer was constructed and experimentally evaluated for charging efficiencies and losses of ultrafine particles in the size range of 15–75 nm at different corona voltage, ion trap voltage and particle flow rate. The corona voltage was applied to the...
Ausführliche Beschreibung

Abstract For this study, a unipolar corona-based ionizer was constructed and experimentally evaluated for charging efficiencies and losses of ultrafine particles in the size range of 15–75 nm at different corona voltage, ion trap voltage and particle flow rate. The corona voltage was applied to the ionizer between 2.0–3.0 kV. The discharge currents increased from 0.16 nA to 4.23 μA and the ion number concentration increased from 6.27 × $ 10^{9} $ to 1.36 × $ 10^{14} $ ions/$ m^{3} $. Increasing the corona voltage lead to a higher discharge current and ion number concentration in the ionizer. The best intrinsic charging efficiency of the ionizer was about 92.15–99.33% for particle diameters ranging from 15 to 75 nm, and occurred at corona voltage, ion trap voltage and particle flow rate of about 3.0 kV, 100 V, 0.6 L/min, respectively. At a given corona voltage, the extrinsic charging efficiency increased as the particle flow rate increased. The best extrinsic charging efficiency ranged from 14.93 to 57.70% for particle diameters increasing from 15 to 75 nm, and occurred at corona voltage, ion trap voltage and particle flow rate of about 2.6 kV, 100 V, and 1.5 L/min, respectively. In the present ionizer, the highest electrostatic loss was observed for particles with a diameter of about 45 nm, and it was about 88.03% at a corona voltage of 3.0 kV and an ion trap voltage of 200 V. Finally, the highest diffusion loss of about 22.66% was seen to occur with singly charged particles with a diameter of 15 nm at the particle flow rate of about 0.6 L/min. Ausführliche Beschreibung