Precipitation of inhalable smoke particles using electrostatic ultrasonic nozzle

The paper presents the result of a research study on precipitation efficiency of inhalable dust particles using electrostatically charged water spray generated by an ultrasonic nozzle. During experiments a commercially available ultrasonic nozzle, LECHLER US1, was used to produce water spray under various operational conditions. The spray generated was charged using induction techniques. The optimal position of the charging electrodes, which create electric field with appropriate spatial distribution required to charge the spray to a desired level of specific charge, was established by applying reverse field modelling technique. A finite element computer software was utilised for this purpose. The shape of the spray cone required optimization of electrode geometry and was examined using a Pulnix TM-765 high speed CCD camera in conjunction with a computerised image grabbing system. The experiments were carried out using cigarette smoke as inhalable test particles with a VMD less than 5 μm. The precipitation efficiency was examined using a test chamber and He-Ne laser based sedimentation system. The precipitation efficiency of the smoke was also investigated using bipolar ions created by corona discharge. Based on the experimental results a semi-empirical model has been developed to predict precipitation efficiency for a wider range of spray parameters