Airflow development and distribution, and deposition of particulate matter under the influence of air speed, charging voltage, and initial number concentration

The study aims to evaluate the possible improvement in the particulate deposition efficiency by investigating bipolar charger agglomeration. The particles were derived from biofuel flue gases produced by burning wood chips and wheat straw and were collected in an electrostatic precipitator and a cyclone bunker. A rectangular bipolar DC-agglomeration device with rectangular chambers was designed to stabilise flow and enhance the mixing of charged particles. The charging voltage and airspeed were investigated in the ranges of 12 kV to 17.5 kV and 1 m/s to 5 m/s, respectively. At a maximum charging voltage and constant initial particle number concentration of 2.0∙10 4 1/cm 3 , the change in the airspeed from 5 m/s to 1 m/s resulted in a decrease of the total particle number concentration from 2% to 67%. Agglomeration effect peaked at 30.8% (wood chips) and 25.7% (wheat straw) at 6 mg/s and ±17.5 kV. A further increase in the charging voltage to 17.5 kV resulted in electrical discharges.