Simulation Study of a Novel Cylindrical Micro-Electrostatic Particulate Air Filter with High Filtration Efficiency and Low Resistance

The purification of indoor pathogenic microorganisms has become a topic of concern. The use of nonwoven media air filters causes high resistance, and the problem of noise limited their application under high air volume. Thus, we propose a micro-electrostatic filter, which has improved performance compared to an electrostatic filter, with a new type of cylindrical structure to tackle indoor pathogenic microbial aerosol pollution. Through simulation, it is found that the filtration performance of a cylindrical structure is better than that of a plate structure under all simulation conditions. For particles larger than 1 μm, the shortest theoretical length of the dust collecting plate required for the cylindrical structure is 34% shorter than that for the plate structure. For 0.1 μm particles, the filtration efficiency of the cylindrical structure is nearly 20~30% (the maximum value is 29.76%) higher than that of the plate structure, while the air velocity is 1.5 m/s~2.5 m/s. The resistance of the cylindrical micro-electrostatic filter is only half of that of the combined plate type micro-electrostatic filter, indicating that the cartridge structure has enormous energy-saving potential. The introduction of the quality factor further proves that the integrated filtration performance of the cartridge micro-electrostatic filter is better. The application of cylindrical micro-electrostatic filters in HVAC systems can help improve indoor air quality and reduce health risks.

Efficiency of the Vehicle Cabin Air Filters for Removing Black Carbon Particles and BTEX from the Air Intake

A laboratory study was conducted to evaluate 11 vehicular cabin filters (including electrostatic filters) in removing fine particles. Two filters with charcoal were also evaluated to understand their usefulness in removing five common volatile organic compounds, including benzene, toluene, ethylbenzene, and xylene isomers (BTEX). Filters were found to show considerably different particle filtration efficiencies (FE). Electrostatic filters were found to provide 20–60% better FE across all particle diameters (6–520 nm). For 6 nm particles, FE from 78 to 94% were observed (from the worst to the best filters), while at 520 nm, FE varied from 35 to 60%. The best group of filters provided 44–46% FE for capturing the most penetrating particles (100–300 nm), while the worst group of filters provided only 10–11% FE. The filtration behavior of nominal filters was typically stable (with respect to particle number, black carbon, and particulate matter mass) over the course of 1–2 years of usage. The benefits of the electrostatic filters were significant, but such advantages were observed to gradually dissipate over the course of about 1 year; by then, the electrostatic filter becomes no different compared to a nominal filter in terms of filtration behavior. Charcoal filters showed variabilities in removing BTEX, and removal efficiencies varied from 11 to 41%.

Generation of Negative Air Ions by Use of Piezoelectric Cold Plasma Generator

The negative air ions (NAI) are used for the removal of particles or droplets from the air. In this study, three types of piezoelectric cold plasma generators (PCPG), in combination with cylindrical electrostatic ion filters, are applied for NAI production. The high voltage on the filter cylinder is induced by the electric field from the piezoelectric transformer of the PCPG. To achieve the dc bias, the cylinder of the electrostatic filter is connected to the ground over ultrafast switching diodes. The ion concentrations are measured for different airflows, PCPG powers, and electrostatic filter geometries. The NAI concentration in the order of magnitude of 107 cm−3, and a negative-to-positive ion concentration ratio of over 200 is reached. The production of ozone is evaluated and the PCPG configuration with a minimum ozone production rate is proposed. The ozone concentration below 60 ppb is reached in the airflow of 90 m3/h.

Low-cost device for active saliva droplet filtration and pathogen inactivation

This work presents a device capable of performing sanitization in environments using an electrostatic filter and ultraviolet light. Recognized techniques were employed in an innovative and low-cost construction model, like Corona Discharge and UVC germicidal light, using elements of easy acquisition and construction. The device consists of a tube with several electrostatic filters. On one side of the tube, an exhaust fan is installed to collect the air to be disinfected. So the air passes through the tubes with the electrostatic filter, which is responsible for collecting the particles suspended in the passing air, attracting them to the metal surface. Allied with this, UVC lights are also inserted in the structure, ensuring greater effectiveness in decontaminating the air that passes through the tubes. In the posterior side to the exhaust fan, the disinfected air is returned to the original environment. A Fluid dynamics simulation was made to investigate the airflow in a room. Standard strains for antimicrobial susceptibility testing were used for bioaerosols assay. The result is a low-cost equipment with great potential to deactivate several kinds of viruses, most especially the Sars-CoV-2 (Coronavirus), that is the main responsible for the global health crisis, designed to be used indoors with low ventilation.

Wood ashes from electrostatic filter as a replacement for the fly ashes in concrete

Many concrete technologists are looking for a solution to replace Fly Ashes that would be unavailable in a few years as an element that occurs as a major component of many types of concrete. The importance of such component is clear - it saves cement and reduces the amount of CO2 in the atmosphere that occurs during cement production. Wood Ashes from electrostatic filter can be used as a valuable substitute in concrete. The laboratory investigations showed that the wood ash concrete had a compressive strength comparable to coal fly ash concrete. These results indicate that wood ash can be used to manufacture normal concrete.

Electrostatic Filters to Reduce COVID-19 Spread in Bubble CPAP: An in vitro Study of Safety and Efficacy

<b><i>Background:</i></b> Bubble CPAP may be used in infants with suspected or confirmed COVID-19. Electrostatic filters may reduce cross infection. This study aims to determine if including a filter in the bubble CPAP circuit impacts stability of pressure delivery. <b><i>Methods:</i></b> A new electrostatic filter was placed before (pre) or after (post) the bubble CPAP generator, or with no filter (control) in an in vitro study. Pressure was recorded at the nasal interface for 18 h (6 L/min; 7 cm H₂O) on 3 occasions for each configuration. Filter failure was defined as pressure &#x3e;9 cm H₂O for 60 continuous minutes. The filter was weighed before and after each experiment. <b><i>Results:</i></b> Mean (SD) time to reach the fail point was 257 (116) min and 525 (566) min for filter placement pre- and post-CPAP generator, respectively. Mean pressure was higher throughout in the pre-generator position compared to control. The filter weight was heavier at end study in the pre- compared to the post-generator position. <b><i>Conclusions:</i></b> Placement of the filter at the pre-generator position in a bubble CPAP circuit should be avoided due to unstable mean pressure. Filters are likely to become saturated with water over time. The post-generator position may accommodate a filter, but regular pressure monitoring and early replacement are required.

Humidification and the HME filter

The process of intubation and ventilation bypasses both the physiological humidification system and protective filtering processes. Various devices have been developed to aid in providing humidification of medical gasses and to serve as filters to reduce transmission of microbes. The following types of devices are available: * Heat and moisture exchanger without filter (HME) * Electrostatic filter with or without HME * Pleated filter with or without HME

Time-focusing time-of-flight, a new method to turn a MAC-E-filter into a quasi-differential spectrometer

Spectrometers based on the magnetic adiabatic collimation followed by an electrostatic filter (MAC-E-filter) principle combine high angular acceptance with an excellent energy resolution. These features make MAC-E-filters very valuable for experiments where the kinetic energy of ions or electrons from rare processes has to be measured with utmost sensitivity and precision. Examples are direct neutrino mass experiments like KATRIN which investigate the energy of electrons in the endpoint region of the tritium $$\beta $$ β -spectrum. However, the MAC-E-filter is a very sharp energy high-pass filter but not a differential spectrometer. To determine a spectral shape of a charged particle source, different electric retarding potentials have to be used sequentially, reducing the statistics. In a previous work we have shown that the advantages of the standard MAC-E-filter can be combined with a measurement of the time-of-flight (TOF), allowing to determine spectral information over a certain energy range with one retarding potential only, with the corresponding gain in statistics. This TOF method requires one to know the start time of the charged particles, which is not always possible. Therefore, we propose a new method which does not require the determination of the start time and which we call “time-focusing time-of-flight” (tfTOF): by applying a time dependent acceleration and deceleration potential at a subsequent MAC-E-filter, an energy dependent post-bunching of the charged particles is achieved.

Electrostatic filters to reduce COVID-19 spread in bubble CPAP: an in vitro study of safety and efficacy.

Background: Bubble CPAP may be used in infants with suspected or confirmed COVID-19. Electrostatic filters may reduce cross-infection. This study aims to determine if including a filter in the bubble CPAP circuit impacts stability of pressure delivery. Methods: A new electrostatic filter was placed before (pre) or after (post) the bubble CPAP generator, or with no filter (control) in an in vitro study. Pressure was recorded at the nasal interface for 18 h (6 L/min; 7 cmH2O) on three occasions for each configuration. Filter failure was defined as pressure >9 cmH20 for 60 continuous minutes. The filter was weighed before and after each experiment. Results: Mean (SD) time to reach the fail-point was 257 (116) min and 525 (566) min for filter placement pre- and post-CPAP generator, respectively. Mean pressure was higher throughout in the pre-generator position compared to control. The filter weight was heavier at study end in the pre- compared to the post-generator position. Conclusions: Placement of the filter at the pre-generator position in a bubble CPAP circuit should be avoided due to unstable mean pressure. Filters are likely to become saturated with water over time. The post-generator position may accommodate a filter, but regular pressure monitoring and early replacement are required.