Design Principles for Sensing Particle Number Concentration and Mean Particle Size With Unipolar Diffusion Charging

• Published in: IEEE sensors journal Vol. 19; no. 4; pp. 1392 - 1399
• Main Authors: Schriefl, M. A., Bergmann, A., Fierz, M.
• Format: Journal Article
• Language: English
• Published: New York IEEE 15-02-2019; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Aerosol instrumentation; Analytical models; Atmospheric measurements; automotive exhaust; Calibration; Charging; Configurations; Current measurement; Diffusion; diffusion charging; Dimensional analysis; Electrostatic measurements; Modelling; particle charging; Particle measurements; particle number concentration; Particle size; real driving emissions; Sensors; Three dimensional models
• ISSN: 1530-437X; 1558-1748
• DOI: 10.1109/JSEN.2018.2880278

Diffusion charging followed by particle capture and measurement is a promising method for determining particle number concentration of automotive exhaust. In addition, the method allows for the determination of a mean particle size, which is of high relevance with respect to health impacts. We investigate three different measurement configurations based on unipolar diffusion charging and electrostatic particle capture, using an analytical non-dimensional model, as well as a transient, multi-physical 3D model. The comprehensive modeling techniques enable prediction of the transient electrical current signals induced by the motion of charged aerosols. Comparison of the multi-physical modeling approach to analytical calculations and experimental data demonstrate model validation. The understanding gained from the modeling techniques enables a study of sensor design and calibration. Particle number concentration sensing is demonstrated for both a modulated precipitation configuration and a two-stage measurement configuration. With the latter, additional information on the mean particle size is extracted.