Electrode geometry effects on the collection efficiency of submicron and ultrafine dust particles in wire-plate electrostatic precipitators

Recent interest in emission control of fine particulate matter has resulted from scientific studies on the effect of fine particulate matter on human health. Hence, many western countries introduced a new emission regulation known as PM2.5, that regulates particles less than 2.5 microns in diameter. The existing particle separation devices such as electrostatic precipitators (ESPs) are of particular interest since they can economically capture particles effectively with a low pressure drop. The present ESPs provide high collection efficiencies of around 99.99% for micron and larger particles. However, the collection efficiency of submicron particles in the range from 0.1 to 1 ~m and ultrafine particles, that is with particle diameters less than 0.1 Jlm, can be less than 50%. In this work, numerical and experimental studies were conducted to examine the effect of electrode geometries on the improvement of collection efficiency of submicron and ultrafine dust particles in electrostatic precipitators. The collection efficiency prediction was based on a modified Deutsche's equation after calculation of the three-dimensional electric potential and ion distribution. The particle charging models for diffusion and field charging methods were considered, based on the Knudsen number (Kn=2A/dp), where Ai is the mean free path of negative ions and dp is the dust particle diameter. The constitutive relationship developed from the optical emission experiments was implemented to simulate ion distribution of corona discharge for various discharge electrodes. Experimental validations for total and partial collection efficiencies for particle size from 10-2 to 20 mm were conducted for bench and full scale ESPs. Results show that the collection efficiency of submicron and ultrafine particles can be predicted with good accuracy for various geometries of discharge and dust collection electrodes. The spike-type discharge electrode with the I-type collecting electrode improves collection efficiency of fine particles when compared to the wire or rod discharge electrode with I-type collecting electrode. In the case of U and C-type collecting electrodes, there is an optimum fin length for which the highest collection efficiency can be reached. Comparison of experimental and predicted results shows that the total collection efficiency predicted by the present model agrees well with experimental results for the bench-scale ESPs. For the large-scale wire-plate type ESP, the present simulation results conducted for various gas temperatures and dust resistivities agree quantitatively and qualitatively with the experimental results. The model proved to be useful for prototype design of collecting and discharge electrodes, modification and existing ESP's and scale-up of new ESP's in order to meet new emission regulations.Doctor of Philosophy (PhD

Modern Surface Engineering Treatments

Surface engineering can be defined as an enabling technology used in a wide range of industrial activities. Surface engineering was founded by detecting surface features which destroy most of pieces, e.g. abrasion, corrosion, fatigue, and disruption; then it was recognized, more than ever, that most technological advancements are constrained with surface requirements. In a wide range of industry (such as gas and oil exploitation, mining, and manufacturing), the surfaces generate an important problem in technological advancement. Passing time shows us new interesting methods in surface engineering. These methods usually apply to enhance the surface properties, e.g. wear rate, fatigue, abrasion, and corrosion resistance. This book collects some of new methods in surface engineering

Advanced Materials and Technologies in Nanogenerators

This reprint discusses the various applications, new materials, and evolution in the field of nanogenerators. This lays the foundation for the popularization of their broad applications in energy science, environmental protection, wearable electronics, self-powered sensors, medical science, robotics, and artificial intelligence

Spacelab Science Results Study

Beginning with OSTA-1 in November 1981 and ending with Neurolab in March 1998, a total of 36 Shuttle missions carried various Spacelab components such as the Spacelab module, pallet, instrument pointing system, or mission peculiar experiment support structure. The experiments carried out during these flights included astrophysics, solar physics, plasma physics, atmospheric science, Earth observations, and a wide range of microgravity experiments in life sciences, biotechnology, materials science, and fluid physics which includes combustion and critical point phenomena. In all, some 764 experiments were conducted by investigators from the U.S., Europe, and Japan. The purpose of this Spacelab Science Results Study is to document the contributions made in each of the major research areas by giving a brief synopsis of the more significant experiments and an extensive list of the publications that were produced. We have also endeavored to show how these results impacted the existing body of knowledge, where they have spawned new fields, and if appropriate, where the knowledge they produced has been applied

Closed-Cycle, Frequency-Stable CO2 Laser Technology

These proceedings contain a collection of papers and comments presented at a workshop on technology associated with long-duration closed-cycle operation of frequency-stable, pulsed carbon dioxide lasers. This workshop was held at the NASA Langley Research Center June 10 to 12, 1986. The workshop, jointly sponsored by the National Aeronautics and Space Administration (NASA) and the Royal Signals and Radar Establishment (RSRE), was attended by 63 engineers and scientists from the United States and the United Kingdom. During the 2 1/2 days of the workshop, a number of issues relating to obtaining frequency-stable operation and to the catalytic control of laser gas chemistry were discussed, and specific recommendations concerning future activities were drafted

Current Air Quality Issues

Air pollution is thus far one of the key environmental issues in urban areas. Comprehensive air quality plans are required to manage air pollution for a particular area. Consequently, air should be continuously sampled, monitored, and modeled to examine different action plans. Reviews and research papers describe air pollution in five main contexts: Monitoring, Modeling, Risk Assessment, Health, and Indoor Air Pollution. The book is recommended to experts interested in health and air pollution issues

Plasma Science and Technology

Plasma science and technology (PST) is a discipline investigating fundamental transport behaviors, interaction physics, and reaction chemistry of plasma and its applications in different technologies and fields. Plasma has uses in refrigeration, biotechnology, health care, microelectronics and semiconductors, nanotechnology, space and environmental sciences, and so on. This book provides a comprehensive overview of PST, including information on different types of plasma, basic interactions of plasma with organic materials, plasma-based energy devices, low-temperature plasma for complex systems, and much more

Advanced Topics in Mass Transfer

This book introduces a number of selected advanced topics in mass transfer phenomenon and covers its theoretical, numerical, modeling and experimental aspects. The 26 chapters of this book are divided into five parts. The first is devoted to the study of some problems of mass transfer in microchannels, turbulence, waves and plasma, while chapters regarding mass transfer with hydro-, magnetohydro- and electro- dynamics are collected in the second part. The third part deals with mass transfer in food, such as rice, cheese, fruits and vegetables, and the fourth focuses on mass transfer in some large-scale applications such as geomorphologic studies. The last part introduces several issues of combined heat and mass transfer phenomena. The book can be considered as a rich reference for researchers and engineers working in the field of mass transfer and its related topics

CHARACTERIZATION AND FLOW PHYSICS OF PLASMA SYNTHETIC JET ACTUATORS

Plasma synthetic jet actuators are investigated experimentally, in which the geometrical design of single dielectric barrier discharge (SDBD) plasma actuators is modified to produce zero-mass flux jets similar to those created by mechanical devices. The SDBD plasma actuator consists of two rectangular electrodes oriented asymmetrically and separated by a layer of dielectric material. Under an input of high voltage, high frequency AC or pulsed DC, a region of plasma is created in the interfacial air gap on account of electrical breakdown of the ambient air. A coupling between the electric field in the plasma and the neutral air near the actuator is introduced, such that the latter experiences a net force which results in a horizontal wall jet. This effect of the actuator has been demonstrated to be useful in mitigating boundary layer separation in aerodynamic flows. To increase the impact that a plasma actuator may have on the flow field, this research investigates the development and characterization of a novel flow control device, the plasma synthetic jet actuator, which tailors the residual air in the form of a vertical jet resembling conventional continuous and synthetic jets. This jet can be either three dimensional using annular electrode arrays, or nearly two dimensional using two rectangular strip exposed electrodes and one embedded electrode. Detailed measurements on the isolated plasma synthetic jet reveal that pulsed operation of the actuator results in the formation of multiple counterrotating vortical structures in the flow field. The output jet velocity and momentum are found to be higher for unsteady pulsing as compared to steady operation. In the case of flow over a flat plate, the actuator is observed to create a localized interaction region within which the baseline flow direction and boundary layer characteristics are modified. The efficiency of the actuator in coupling momentum to the neutral air is found to be related to the plasma morphology, pulsing frequency, actuator dimension, and input power. An analytical scaling model is proposed to describe the effects of varying the above variables on the output jet characteristics and actuator efficiency, and the experimental data is used for model validation