Performance Evaluation of Air Cleaner Filter for Ultra-Fine Particle Penetration: An Air Filtration Application

Filtration efficiency of an electrostatic fibrous filter: Studying filtration dependency on ultrafine particle exposure and composition

The effect of air supply and air exhaust locations on the efficiency of restraining particles from entering the laboratory and the efficiency of particle removal from the laboratory were investigated by simulating the flow conditions, accompanied by a Lagrangian particle-tracking method to calculate the trajectories of the particles in the laboratory. Three cases with air supplied from different locations in the laboratory were used to investigate the restraint and removal effects in the study. The results indicate that for the case with air supplied from the air supply located on the ceiling near the door, the efficiency of restraining particles from entering the laboratory is the best among the three cases. However, for the particle removal efficiency, the case with the air supplied from the air supply located on the ceiling in the center of the laboratory possesses the best removal performance. For the case with air supplied from the air supply located on the ceiling far away from the door, the particle restraint and removal efficiencies are not obvious. By tracing and calculating the trajectories of micro-particles in time, the particle restraint and removal effects can be explicitly indicated by calculating the amount of particles that enter or leave the laboratory. Key words: Particle, air supply, air exhaust, Lagrangian, restraint, removal effects.

The Adjuvant Effect of Ambient Particulate Matter Is Closely Reflected by the Particulate Oxidant Potential

The removal of particulate matter (PM) from air streams is essential for advancing environmental technologies and safeguarding public health. This study explores the performance of an electrostatic precipitator (ESP) in eliminating fine and ultra-fine PM under varied experimental conditions. It uniquely examines the influence of PM size and feed rate on ESP removal efficiency. The system’s use of low voltages enhances energy sustainability, while its innovative design improves corona discharge, leading to significant reductions in fine and ultra-fine PM emissions. Plants using electrical devices are increasingly being incorporated into material processing lines to reduce pollution in the surrounding work area, as well as to collect particle emissions in the atmosphere. It is also possible to recycle some raw materials in this way with low energy consumption. This cleaning technology increases the added value of industrial equipment, which affects its competitiveness and its impact on sustainable manufacturing. The experimental results indicate a steady electrostatic field voltage of 15.1 kilovolts, with an airflow maintained at 0.8 m/s through a doser at 2.5 bar, eliminating the need for a fan. The PM feed rate varied between 2 and 20 mm/h, with six trials conducted to ensure the data were consistent. Preliminary studies devoid of ESP intervention demonstrated little PM removal, since buildup on the chamber walls distorted the results. The installation of the ESF markedly enhanced the removal efficiency, achieving up to 95.5%. Further analysis revealed that ESP performance depended on PM concentration in the agglomeration chamber, achieving a clearance rate exceeding 98% under optimal conditions. Fine PM (0.35 to 8.7 µm) was more efficiently removed than ultra-fine PM (0.2 to 0.35 µm). The highest removal efficiency was observed at a feed rate of 0.962 mg/s, while the lowest occurred at 0.385 mg/s. A strong positive correlation between particle concentration and removal efficiency (Pearson value up to 0.829) was observed, particularly at feed rates of 0.128, 0.641, and 1.283 mg/s. The study’s findings confirm that the ESP is highly effective in removing particulate matter, particularly fine and ultra-fine particles, with an optimal feed rate, significantly enhancing the system’s performance.

ABSTRACTElectrostatic precipitation is considered as an effective technology for fine particle removal. A lab-scale wet electrostatic precipitator (ESP) with wire-to-plate configuration was developed to study particle migration and collection. The performance of the wet ESP was evaluated in terms of the corona discharge characteristics, total removal efficiency and fractional removal efficiency. The corona discharge characteristics and particle removal abilities of the wet ESP were investigated and compared with dry ESP. Particle removal efficiency was influenced by discharge electrode type, SO2 concentration, specific collection area (SCA) and particle/droplet interaction. Results showed that the particle removal efficiency of wet ESP was elevated to 97.86% from 93.75% of dry ESP. Three types of discharge electrodes were investigated. Higher particle removal efficiency and larger migration velocity could be obtained with fishbone electrode. Particle removal efficiency decreased by 2.87% when SO2 concentration increased from 0 ppm to 43 ppm as a result of the suppression of corona discharge and particle charging. The removal efficiency increased with higher SCA, but it changed by only 0.71% with the SCA increasing from 25.0 m2/(m3/s) to 32.5 m2/(m3/s). Meanwhile, the increasing of particle and droplet concentration was favorable to the particle aggregation and improved particle removal efficiency.Implications: This work tends to study the particle migration and collection under spraying condition. The performance of a wet electrostatic precipitator (ESP) is evaluated in terms of the corona discharge characteristics, total particle removal efficiency, and fractional particle removal efficiency. The effects of water droplets on particle removal, especially on removal of particles with different sizes, is investigated. The optimization work was done to determine appropriate water consumption, discharge electrode type, and specific collection area, which can provide a basis for wet ESP design and application.

Enhanced size-dependent efficiency of removal of ultrafine particles: New solution of two-stage electrostatic precipitator with thermophoresis

Permeable pavement is a technology that allows rainwater to infiltrate into the pavement. Permeable pavements not only help reduce surface runoff by allowing rainwater to infiltrate into the pavement, but also improve water quality with the filter layer that removes particulate matter pollutants. This study evaluated the particulate matter removal efficiency of bottom ash-sand mixtures as filter layers for removing fine (≤10 μm) or ultrafine (≤2.5 μm) particulate matter in the laboratory. Five filter media were tested: silica sand, bottom ash, and bottom ash-sand mixtures with 30:70, 50:50, and 70:30 ratios. The mixed filters exhibited more consistent and stable particulate matter removal efficiency over time than either the uniform sand or bottom ash filter. The 50:50 bottom ash-sand mixture demonstrated removal rates of 58.05% for 1.8 μm particles, 93.92% for 10 μm particles, and 92.45% for 60 μm particles. These findings highlight the potential of bottom ash-sand mixtures as effective filter media for removing PM10 road dust, although field validation with actual pavement systems is necessary.

Developing new filters for the effective removal of high-temperature particulate matter is of great importance but still remains a challenge. Herein, we demonstrate a novel and facile strategy for producing hierarchical ceramic foams with three-dimensional interconnected porous architecture via the combination of chemical grafting of pore-forming agent and polyurethane foaming technique. Carbamate groups are directly grafted onto carbon black surface to enhance its dispersion. Abundant micrometer-sized pores are generated on the cell walls of porous frameworks to form three-dimensional interconnected porous architectures, resulting in the mullite foam with high particulate matter removal efficiency and relatively low pressure drop. The optimized mullite foam exhibits integrated properties of high particulate matter removal efficiency (96.7%), ultralow pressure drop (35 Pa), and outstanding recyclability. Our results open new opportunities for fabricating efficient particulate matter filters used in high-temperature environmental fields.

Ambient particulate matter has been associated consistently with an increased risk for mortality largely due to cardiovascular diseases.1 Although the relative risk estimates from epidemiological studies are small, they apply to almost the entire population of the United States. Consequently, exposure to ambient particles produces considerable burden of disease, and its mitigation offers the benefit of improving life expectancy.2 Articles see pp 941 and 949 Over the past decade, research has substantiated the understanding of the pathophysiological mechanisms linking ambient particles to the cardiovascular system3,4 once it was noted that ambient air pollution elicits systemic inflammatory responses in the general population.5 An update of the American Heart Association statement on air pollution and cardiovascular disease3 is under way. Mechanisms considered for active and secondhand smoke as well as ambient air pollution are strikingly similar.4,6,7 They include progression of atherosclerotic plaques to vulnerable forms, prothrombotic states, endothelial dysfunction, and altered autonomic nervous system control (Figure). Increased systemic oxidative stress is considered the key mechanism responsible for most of these pathophysiological changes. Increased risks for cardiovascular disease in general and coronary artery disease in particular have been documented for active and secondhand smoke as well as ambient particulate matter. Deep venous thrombosis has been added to this list recently.8 Figure. Overview on pathomechanism linking ambient air pollution,4 secondhand smoke,7 and active smoking to acute coronary syndromes. Nevertheless, the public health relevance of particulate matter in the light of the smoking literature remains hotly debated. Smokers are exposed to considerably higher cumulative doses of particulate matter than the general nonsmoking population. Mortality due to low doses of ambient particles may be considered counterintuitive compared with doses of particles tolerated by smoking individuals. A systematic assessment of the exposure-response function ranging from low doses of inhaled particles …

Extreme ultraviolet lithography (EUVL) is the most promising lithography technique for the 22 nm half-pitch and beyond. The EUV patterned masks work in a reflective mode and it has 40 to 50 pairs of MoSi multilayer to reflect EUV radiation. This multilayer is capped by a 2.5 nm Ru thin film to protect the MoSi multilayer. Since EUV mask does not have a pellicle which protects mask surface from the contaminants. Therefore, EUV mask is more vulnerable to particle contamination during lithography processing which is a major yield loss in device fabrication. No study has been reported on the effect of particle size on CD variation if they exist on EUV mask. The critical defect size, which can cause 10 % CD error, has to be removed from the mask surface. When the defect is located between line and space patterns on the mask, the reflectivity will be reduced due to defect absorption. Simulation predicted that 30 nm sized silica particles can cause 10 % CD error on 16 nm line and space pattern. Thus, these contaminant particles have to be removed from EUV mask surface for preventing CD variation. In order to evaluate the 30 nm sized silica particle removal test, we adopted 30 nm standard spherical silica particles. Actually, it is a challenge to evaluate 30 nm particles removal test without inspection tools. So, we used atomic micro scope (AFM) for the evaluation of these particles. The silica particles were intentionally deposited on Ru surface using spinning method. Cleaning test was performed with twin type megasnoic. 30 nm silica particles removal efficiency was drastically decreased as compared with 137 nm silica particles at 1 MHz megasonic cleaning. Because the megasonic cleaning force was reduced to ultra-fine particles due to boundary layer thickness. Therefore, higher megasonic cleaning force is required to remove ultra-fine particles to overcome boundary layer thickness. It is well known that the large cleaning force is induced, not only particle removal efficiency but also pattern damage will be increased. Thus, megasonic cleaning process without causing pattern damage has to be optimized.In this study, we shall discuss the effect of megasonic frequency on the removal of ultra-fine particles and pattern damage. Also, gas dissolved water and dilute alkali cleaning solution are adopted to high frequency megasonic cleaning process to achieve ultra-fine particles removal without pattern damage effectively. Figure 1

Fine particulate: it matters.

The RCA cleaning process is a standard wet cleaning process for removal of contaminants from silicon wafer surface. As well known, the SC1 cleaning solution which consists of a mixture of NH4OH (ammonium hydroxide), H2O2 (hydrogen peroxide) and H2O is an efficient particle removal. Cleaning mechanism of SC1 cleaning solution on particles removal from silicon surface is slightly surface etching and lift off the particles from the Si surface by electrostatic repulsive force between particles and surface. SC1 cleaning process may etch a few angstrom (Å) level of silicon surface. However, metal contaminant which has a high redox potential is critical when bare silicon is exposed. Metal deposition on Si surface is induced by the oxidation reduction reaction between metal ion and Si surface. Metal ion can take electrons from Si surface and are reduced to become metal. Si surface beneath the metal particles is oxidized to become SiO2 and is etched away by OH- in SC1 solution. The metal pit is a form of localized etching that leads to the creation of small hole under the metal. Thus, the etching has a crucial effect on the formation of defects and removal of particles. The etch rate of Si increased with NH4OH concentration whereas it decreased with H2O2 concentration. This indicates that metal pitting increased with NH4OH concentration while H2O2 inhibits it. However, particle removal efficiency (PRE) decreased in high H2O2concentration. Particle removal is affected by etch rate and pH of cleaning solution. For high pH value in the SC1 solution, particles take on a strongly negative charge. The particles are repelled from a Si surface. This electrostatic interaction prevents recontamination by particles to Si surface. Therefore, it is important to optimize SC-1 cleaning process in Si surface cleaning process. In this study, we investigated the relationship between PRE, surface etch rate and removal of metal contaminant with various concentrations of SC1 cleaning solution. The thermally oxidized 200 mm p-type Si (100) wafers were used. To identify relationship between etch rate and formation of defect, etch depth was measured for various composition of SC-1 solution by using atomic force microscopy. The Cu ions were used as a source of metal pitting to making Cu precipitate on Si surface. Si wafers were contaminated with Cu ions and particles by dipping method. Cu precipitate and particles on Si surface were counted using atomic force microscopy and a dark field optical microscope to confirm cleaning efficiency of SC1 solution. Etching of Si wafer surface in SC1 solution was evaluated as a function of composition of SC1 solution. It was shown that Cu precipitates decreased with H2O2 concentration in SC1 solution. But PRE also decreased. It was suggested that H2O2 reduced the formation of Cu precipitates and PRE was dependent of NH4OH concentration. This study proposes cleaning process to minimize Cu precipitates with a high PRE in the optimized SC1 solution. Figure 1

Feasibility of applying an electrostatic precipitator integrated with a naturally ventilated double-skin façade in residential buildings

Experimental evaluation of separation performance of fine particles of circulatory circumfluent cyclone separator system

IIt has been assumed that damage from exposure to tobacco smoke and other particulate air pollutants is imposed primarily on the lungs and is associated with increased morbidity and mortality rates in patients with preexisting lung disease. This is supported by a considerable amount of previous data, such as the mortality data from the December 1952 London smog disaster, which may have caused as many as 12 000 deaths, almost all in patients with preexisting lung disease.1 Total suspended particulate matter (PM) was as high as 3000 μg/m3. Similar patterns of elevated morbidity and mortality rates, primarily in patients with preexisting lung disease, have been documented in other acute episodes of air pollution in the past.2 However, evidence from the past 10 years shows that sudden increases in ambient air pollution can also rapidly raise morbidity and mortality rates in patients with existing cardiovascular disease, as much or more than the rise associated with lung disease. In the present issue of Circulation , Pope and associates3 report interesting new data on the effects on mortality rate of long-term differences, as opposed to sudden transient increases, in levels of air pollution. Data were derived from a large, comprehensive study initiated by the American Cancer Society and linked to cancer prevention. The study involved a large population of subjects enrolled in 1982 from metropolitan centers in all 50 states and Puerto Rico. Vital status of participants was collected every 2 years for the subsequent 16 years, and a cause of death was identified for 98% of the known fatalities. Metropolitan area of residence was known for each participant, and particle counts of fine particulates were averaged over quarterly intervals throughout the year for each included metropolitan area. A questionnaire provided additional data, allowing for differences in mortality …