6 research outputs found
Superposition of DC voltage and submicrosecond impulses for energization of electrostatic precipitators
No full textThis paper discusses the development of an impulsive microelectrostatic precipitation technology, which uses superposition of submicrosecond high-field pulses and dc electric field. Short impulses allow the application of higher voltages to the ionization electrodes of a precipitation system without the initiation of breakdown. These higher levels of electric field generate higher ionic concentrations, resulting in more efficient charging of the airborne particles, and can potentially improve precipitation efficiency. This work is focused on the analysis of the behavior of impulsive positive corona discharges in a coaxial reactor designed for precipitation studies. The efficiency of precipitation of coarse and fine particles has been investigated using different dc and impulse voltage levels in order to establish optimal energization modes
Investigation of high altitude/tropospheric correction factors for electric aircraft applications
No full textWith rising fuel costs and CO2 emissions, the aviation industry is moving rapidly toward increased electrification of aircraft, and power demand for propulsion and safety critical systems necessitates a move to on-board distribution voltages in excess of 1 kV. The increased stress experienced by cable insulation, connectors and other equipment, combined with extreme and dynamic environmental conditions experienced in flight, presents a number of technical challenges.
This research project proposes to quantify the effect of atmospheric conditions on partial discharge thresholds in uprated aircraft electrical systems, and to derive atmospheric correction factors appropriate to in-service operating conditions to assist the aircraft electrical design engineer in the insulation coordination of modern aviation systems.
The development of a controlled atmospheric test facility for the precise replication of in-flight conditions is outlined, and an initial visual assessment of partial discharge activity in an ex-service wire harness at a range of pressures is presented. We also present plans for the ongoing development of the facility and test capabilities
Analysis of particle charging mechanism for optimisation of precipitation efficiency
No full textThe present paper analyses the space charge influenced electric field in a coaxial electrostatic precipitation reactor and discusses the charging process of particles in an impulsive electric field. An analytical expression for the transient non-compensated charge on the particle surface has been obtained. It has been shown that this charge depends of the dielectric properties of the external medium and the particle. The efficiency of micro-electrostatic precipitation process (μ-ESP) in which a combination of DC voltage and high voltage impulses is used to energise the double stage precipitation reactor has been evaluated. It has been shown that this μ-ESP process can provide high removal efficiency for particles as small as 250 nm
The use of impulsive corona discharges for the removal of fine particles in a novel coaxial electrostatic precipitator
No full textSummary form only given. Power plants, internal combustion engines and other sources produce micron and sub-micron particles, which contaminate the air. This problem is faced mainly in large cities where both population and industrial activities are higher leading to significantly reduced air quality. Recent research has pointed out particles less than 2.5 μm in diameter (PM2.5) as a potential health hazard. In the light of these results directives and strict legislation has been put into force in order to reduce PM2.5 emissions. This research paper is focused on an impulsive microelectrostatic precipitation technology in order to charge and remove suspended particles from the air in an economically feasible way. HV impulses together with dc voltage has been used in order to energise the reactor as it has been shown to enhance the precipitation efficiency. In the present work a compact, yet larger in scale, coaxial precipitator has been developed for possible indoor applications. This precipitation system has been tested for removal of smoke and fine airborne particles from ambient air. In addition to the experimental part, analytical work has been conducted in order to optimize the electrostatic precipitation process and reduce power consumption
Removal of fine and ultrafine particles from air by microelectrostatic precipitation
No full textParticles with dimensions less than 2.5 μm (PM2.5) have been identified as being potentially hazardous to human health. The electrostatic precipitation process, which is mainly used in industrial applications, displays a drop in the precipitation efficiency for particles in the range 0.1-1 μm. This paper is focused on the development of an impulsive microelectrostatic precipitation (μ-ESP) technology for indoor air cleaning applications. Short (microsecond) high-voltage impulses are used in this technology, which allows the magnitude of the electric field that particles experience to be increased without complete spark breakdown occurring and also reduces the energy consumption compared to that of dc-energized systems. The charging process of particles in the impulsive electric field used in the reactor has been analyzed. Ambient laboratory air and air-diluted cigarette smoke, which contain a significant proportion of PM2.5 particles, were used in the precipitation tests. In order to optimize performance for the μ-ESP process, different energization modes of the developed precipitation reactor were studied: dc energization, impulsive energization, and their combination. It has been shown that combined dc and impulsive energization of the two stage μ-ESP reactor produces the maximum precipitation effect. In both cases, ambient laboratory air and diluted smoke, 100% precipitation efficiency has been achieved for fine (250 nm and above) particles; in the tests with diluted smoke, a fine mesh filter was incorporated in the precipitation system to achieve this level of performance
Sub-microsecond impulsive corona discharges for electrostatic precipitation applications
No full textThe present paper discusses the development of the impulsive micro-electrostatic precipitation technology (μ-ESP), which uses superposition of sub-microsecond high field pulses and DC electric field. Short impulses allow the application of higher voltages to the ionisation electrodes of a precipitation system without the initiation of breakdown. These higher levels of electric field generate higher ionic concentrations, resulting in more efficient charging of the airborne particles and can potentially improve precipitation efficiency. The present work is focused on analysis of the behavior of impulsive positive corona discharges in coaxial reactor designed for precipitation studies. The efficiency of precipitation of coarse and fine particles has been investigated using the different DC and impulse voltage levels in order to establish optimal energisation modes
