Charging Efficiency of the Electrical Low Pressure Impactor's Corona Charger: Influence of the Fractal Morphology of Nanoparticle Aggregates and Uncertainty Analysis of Experimental Results

摘要

The charging efficiency function of the Electrical Low Pressure Impactor (ELPI) corona charger was estimated for spherical, cubical, and fractal particles having an electrical mobility diameter D_b ranging from 0.01 to 0.5 mu m. Uncertainty analysis was performed on the experimental results for comparison with previous results for reference aerosols (spherical and cubical). Significant discrepancies were observed for the reference aerosols relative to Marjamaki et al. (2000,2002). For fractal particles, charging efficiency follows a power-law function; the coefficients show significant discrepancies with those estimated for the reference aerosols. Consequently, fractal particles present higher charging efficiency than reference particles with a similar electrical mobility diameter. Two approaches are proposed to estimate the equivalent charge diameter of particles denoting fractal morphology. The work of Rogak and Flagan (1992) provides the best agreement between the experimental results and the theoretical representation of the ELPI charging efficiency.