Theoretical and experimental evaluation of a mixing-type bipolar charger using corona-discharge at high pressure

A Mixing-type Bipolar Charger using Corona-discharge at High Pressure (MBCCHP) is subjected to both theoretical and experimental evaluation. In theoretical studies, the charging model for the MBCCHP is developed to determine the influences of the residence time t_R, the number ratio of negative ions to positive ions N^- /N⁺, and the number ratio of particles to bipolar ions n₀/N_B (where N_B=N⁺+N^-) on the charge distribution. The charge distribution recorded experimentally at various values of n₀ /N_B and N^-/N⁺ is compared with theoretical results. The comparisons indicate that the theoretical results can be used to adequately explain well the experimental data. Both sets of results demonstrate that the MBCCHP is capable of generating equilibrium charge distributions of aerosol particles within errors of 10%. The diameter of the particles ranges between 10-500 nm and the particle number concentration n0 is less than 3.0 × 10¹²m^-3 under operating conditions of 0.5>t_R> 0.1 s, with a frequency >100 Hz, a voltage of 9.0 kV_0-P, and a high-pressure ionizer operating at 0.4MPa.