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The purpose of this article is to show the validity of the simulation result for particle charge and trajectory in an electrostatic precipitator (ESP) with multiple wire electrodes, and the effect of the number of wire electrodes on the relationship between collection efficiency and discharge power. The ESP in this article has wires-and-plates configuration. The potential, the electric field intensity, the negative ion density, the ionic gas flow, the charge of the particles and the charged particle trajectory in the ESP were calculated. In the experiment, the charged particle trajectory was measured by a particle image velocimetry (PIV). In addition, the analysis and the experimental collection efficiencies as a function of input power in the ESPs with a single wire electrode and three wire electrodes were compared, and the effect of the number of wire electrodes on the power consumption was investigated. As a result, the x and y components of the particle velocity measured using the PIV almost agreed with the simulated result. The validity of the simulation result for charged particle trajectory, which was calculated by fitting the analyzed corona current to the experimental value, in an ESP with multiple wire electrodes was demonstrated. Also, both analysis and experimental collection efficiencies by the ESP with three wire electrodes were greater than those with the single wire electrode at the same input power. An analysis revealed that this was because the residence time of the particles in the ESP with three wire electrodes was longer than that with the single wire electrode. [ABSTRACT FROM AUTHOR]

In this article, an electrostatic precipitators (ESP) with high electric field, which does not use corona discharge, was investigated. The ESP had a parallel plate configuration composed of a high voltage application plate electrode and grounded plate electrode with a gap of 5 mm. The electrode length was between 150 and 450 mm. The air was flowed at the gas velocity between 0.5 and 5 m/s in the ESP by a fan. A voltage up to 12.5 kV was applied to the high voltage application electrode, whereby the electric field intensity of 25 kV/cm was generated between the electrodes. The particle concentration in the air for the particle size between 0.3 and 5 μm was measured to calculate the collection efficiency. The collection efficiency in a conventional two-stage type ESP was also measured, and compared to the result in the ESP with high electric field. As a result, the collection efficiency at the electrode length of 450 mm was 77.6% at 12.5 kV, when the ratio of the input power was lower than 0.33 W/(m3/s), in the ESP with high electric field. On the other hand, the collection efficiency in the conventional ESP was 65.6% or 82.0% at the input power of 14.2 W/(m3/s) or 24.8 W/(m3/s). Therefore, it is revealed that the ESP with high electric field is effective for energy saving. [ABSTRACT FROM AUTHOR]

The aim of this paper is to evaluate the collection efficiency of submicron particles using electrically charged nonwoven filter media. A triode-type electrode arrangement consisting of a high-voltage wire-type ionizing electrode, a metallic grid, and grounded plate electrode is employed to control the distribution of electric charges deposited on the media. Surface electric potential measurement is carried out to study the evolution in time and the repartition in space of deposited charges. The collection efficiency is estimated by measuring the particle concentrations downstream and upstream of the charged filter media. The main results show good correlation between the surface potential level and the collection efficiency of submicron particles for several charging conditions. In particular, filtration performance increases with increasing the corona current through the media during the charging process. Increasing the electric field between the grid and the media during corona charging has also a positive effect on the collection efficiency. Results indicate that high collection performances could not be achieved using thin monolayer media. [ABSTRACT FROM AUTHOR]

In this paper, particle velocity fields inside three electrostatic precipitators (ESPs) are investigated experimentally using particle image velocimetry (PIV). The reference case is a typical wire-to-plane ESP under negative and positive dc high voltages. The two other ESPs use an ac high voltage to generate a dielectric barrier discharge (DBD) in wire-to-plane and plane-to-plane configurations. The main objective of this paper is to analyze the effect of the ionic wind on the particle collection efficiency in such systems. The high voltage magnitude and the frequency are the major parameters taken into account. With the wire-to-plane ESPs, PIV results show a strong interaction between the primary flow and the secondary flow (ionic wind). Near the wire electrode, the strong electric forces move the particles from the central part of the channel to the plate electrodes. Within the drift region, the velocity magnitude depends essentially on the balance between the electric and viscous forces. With this configuration, the particle trajectory is 3-D. In the case of the plane-to-plane ESP, a 2-D analysis of the time-averaged flow can be accepted. The time-averaged flow is only modified in the boundary layer, which becomes thinner. The time-averaged effect of the ionic wind on the primary flow in such a configuration is negligible. The correlation between the electrohydrodynamic flow and the collection efficiency shows that increasing the ionic wind magnitude did not improve necessarily the electrostatic precipitation effectiveness of submicrometer particles, particularly using DBD precipitators. [ABSTRACT FROM AUTHOR]

A novel wet electrostatic precipitator is designed for control of fine aerosol from humid effluent gases. It operates on the principle of unipolar particle charging in a dc corona discharge in a high-velocity (> 20 m/s) ionizing stage and aerosol precipitation in the low-velocity (< 3 m/s) collection stage under the field of the particle's own space charge. The high gas velocity in the ionizing section diminishes the corona suppression at high particle number concentrations of H2SO4 and HCl aerosol. [ABSTRACT FROM AUTHOR]

Portable air cleaners are becoming increasingly popular in household applications. Many different designs and technologies are currently available, and most cleaners are striving for Energy Star certification that requires certain performance and electrical efficiency levels. One of the most important criteria is electrical efficiency. The appliance has to be at least two CADR/W, where CADR is Clean Air Delivery Rate as measured per ANSI/AHAM AC-1-2002 standard and W is input power of the air cleaner. However, there are only a few serious attempts to significantly improve the efficiency of such devices beyond that required by Energy Star standards. This paper investigates relationships between intensity of the electric field inside the collector assembly of an electrostatic precipitator (ESP) and the effectiveness of the ESP operation. Single-pass collection efficiency and other parameters of the ESP were measured under various conditions and optimized for performance and energy efficiency. This paper describes a new collector assembly design. It allows an increase of the electric field in the collection area of the ESP of more than two times when compared to the electric field in conventional ESP designs. This results in an increase in single pass collection efficiency. Other improvements lead to an extremely efficient design that achieves electrical efficiencies as high as 15 to 20 CADR/W compared to the five CADR/W that only a few of the best models can demonstrate. Testing of the new design confirmed the expected bactericidal effect of the technology. The combination of a strong electric field, plasma of the corona discharge and ozone generated during ESP operation effectively kill the microorganisms. All three components (electric field, plasma and ozone) are created as byproducts of ESP operation and do not require additional energy input. Unique catalytic filters optimized for the design remove the ozone without excessive energy consumption. As a result, this new technology, does a better job of removing particles from the air, using less than 30% of the energy of the best rated portable air cleaners and kills bacteria in the air at the same time. The significance of this paper is particularly important for possible industrial and commercial applications where energy savings could be considerably more beneficial than in consumer applications. [ABSTRACT FROM AUTHOR]