M. Lackowski

Efficiency of smoke removal by charged water droplets

The removal of fine aerosol particles such as dust or smoke by charged droplets was investigated experimentally. The droplets were sprayed by a rotary atomiser and simultaneously charged inductively. The cigarette smoke was used as a source of submicrometer dust. Smoke was charged in a specially designed corona-discharge charger. The suppression of particle concentration was determined after different time intervals of spraying of water. The electrical charging of droplets significantly increases the efficiency of removal of fine particles from air as compared to the uncharged aerosol. Further improvement was obtained after charging smoke particles. The cleaning process was up to four times better for charged smoke and droplets than that for uncharged species.

Unipolar charging of aerosol particles in alternating electric field

Abstract Electrostatic charging of fine aerosol particles in an ionic current and alternating electric field enables charge imparted to the particle to be close to the Pauthenier limit. The charging process was simulated numerically and compared with the experimental results. The numerical simulation takes into account the gravitational, drag, inertial and electrohydrodynamic forces influencing the particle motion in the alternating electric field charger. The increase in the charge on the particle during its flow through the charger and the effect of the frequency of the electric field on the charging process were also determined.

Dust particles motion in back discharge

The back discharge is a type of discharge that takes place in the electrostatics precipitation process, especially in coal-fired power plants for coal of low content of sulfur. This type of discharge takes place in the presence of corona discharge and occurs on an electrode covered with a high resistivity dust layer. The breakdown of dielectric layer causes an increase in the discharge current and re-entrainment of dust particle from collection electrode into the flowing gas. The investigations of the motion of dust particle emitted from the collection electrode are presented in this paper. Additionally, acrylic powder layer placed between a mica plate with a small pinhole and the plate electrode were also used in the experiments in order to generate repeatable back discharge. An effect of back discharge on the collection efficiency in the electrodes system was also presented.

Electrostatic method for the production of polymer nanofibers blended with metal-oxide nanoparticles

The paper presents investigations of a method of the production of non-woven polymer fabrics with incorporated metal oxide nanoparticles based on electrospinning and electrospraying. Two main configurations of electrospraying/electrospinning systems have been tested: two-step process of electrospinning of polymer solution followed by electrospraying of nanoparticle suspension, and simultaneous electrospinning of polymer solution and electrospraying of nanoparticle suspension. By this method TiO2, MgO, or Al2O3 nanoparticles of the size from 20 to 100 nm were deposited onto electrospun PVC nanofibers.

Spectroscopic studies of back-discharge

Different forms of low current back-discharge in air at atmospheric pressure with fly ash used as a dielectric barrier are discussed in the paper. The discharge was characterized in terms of optical emission spectra and current-voltage characteristics. The discharge emission spectra in the wavelength range of 200÷540 nm have been measured to investigate behavior of the species present in the fly ash when back-discharge is initiated. In normal conditions the emission spectra are dominated by atmospheric components (molecular nitrogen, atomic oxygen and nitrogen) but atomic lines due to chemical composition of the fly ash were also identified.

Nanofabric nonwoven mat for filtration smoke and nanoparticles

The process of production of filtration mats of various thickness from PVC and PVDF polymers by the electrospinning method is presented in the paper. Filtration of nanoparticles and submicron particles is an important problem in industry and health protection systems, in particular in air-conditioning and ventilation appliances. This problem can be effectively solved by application of non-woven fibrous filtration mats. The experimental investigations of mechanical properties of nanofibrous filtration mats produced by electrospinning and the measurements of removal efficiency of submicron particles from flowing gas have indicated potential usefulness of these nanomats for gas cleaning of air-conditioning systems and/or ventilation ducts. The experimental results obtained for cigarette smoke of a mass median diameter of about 1 μm, used as test particles, have shown that nonwoven nanofibrous filtration mats produced by electrospinning have a good filtration efficiency for nano- and submicron particles, owing to a pressure drop similar to HEPA filters. Particles of this size are particularly difficult to be removed from the flow by a conventional method, for example, by a cyclone or electrostatic precipitator.

Studies of Low‐Current Back‐Discharge in Point‐Plane Geometry with Dielectric Layer

The paper presents results of spectroscopic investigations of back‐discharges generated in the point‐plane electrode geometry in ambient air at atmospheric pressure, with the plane electrode covered with a dielectric layer. Fly ash from an electrostatic precipitator of a coal‐fired power plant was used as the dielectric layer in these investigations. The discharges for positive and negative polarities of the needle electrode were studied by measuring optical emission spectra at two regions of the discharge: near the needle electrode and dielectric layer surface. The visual forms of the discharge were recorded and correlated with the current‐voltage characteristics and optical emission spectra. The back‐arc discharge was of particular interest in these studies due to its detrimental effects it causes in electrostatic precipitators.