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Diagram of the modified cyclone dust collector. 1 -inlet tangential nozzle, 2 -outlet nozzle, 3 -casing, 4 -ultrasonic disk radiator, 5 -separation chamber, 6 -bunker; 7 -direction of gas flow in the separation chamber (upstream), 8 -direction of particles in the bunker, 9 -downstream. https://doi.org/10.1371/journal.pone.0239593.g004
Source publication
The method for increasing the separation efficiency of particles smaller than 2.5 micrometers by combined ultrasonic agglomeration and swirling flow technique is proposed in the article. The swirling flow creates areas with an increased concentration of particles on the outer radius of the vortex. The ultrasonic exposure on these areas leads to mor...
Contexts in source publication
Context 1
... confirm the effectiveness of the proposed method of cleaning gases from the dispersed particles, the device for forming a swirling flow (the agglomerator) was completed with a known cyclone dust collector [39]. The cyclone dust collector was modified by installing an ultrasonic disk radiator, which was developed by the authors (Fig 4). The cyclone dust collector inlet was connected to the agglomerator outlet. ...
Citations
... For these reasons, the low probability of particle collision, especially at low concentrations (large distances between particles) leads to the fact that, even at the maximum permissible sound pressure level (before the destruction of the formed agglomerates), increasing the efficiency of agglomeration of particles smaller than 2.5 µm due to ultrasonic vibrations becomes virtually impossible. For example, in [19] it is shown that ultrasonic coagulation studies were carried out under conditions of high mass concentration of particles in the range from 0.2 to 5 g/m 3 . Such conditions are typical during the production of any product and its capture in the form of highly dispersed particles. ...
... In [19,23], it was proposed to increase the efficiency of agglomeration by swirling the flow with dispersed particles at the entrance to the agglomeration chamber. Due to this, a swirling flow is created in the agglomeration chamber and the particles (under the influence of centrifugal forces) are pushed to the outer part of the vortex. ...
The article is devoted to the study of ultrasonic agglomeration of PM 2.5 in homogeneous and inhomogeneous ultrasonic fields. The possibility of increasing the efficiency of ultrasonic agglomeration by initiating acoustic streams in a resonant inhomogeneous ultrasonic field is shown. A inhomogeneous ultrasonic field with zones of high and low sound pressure levels formed using a bending-oscillating disk transmitter made it possible to initiate acoustic vortex-type streaming that promotes the movement of particles into the nodal areas of a standing wave and between them. Due to the formation of a inhomogeneous ultrasonic field, the efficiency of particle collection is increased: for PM 2.5, the efficiency reaches 95%; PM 1.5—92%; PM 0.5—85%. The results were obtained under the following conditions: concentration 2 × 10−2 g/m3, sound pressure level 165 dB, flow rate 6.2 m3/h. For comparison, when a homogeneous ultrasonic field is formed in the agglomeration chamber (under similar conditions), the efficiency of particle capture by inertial gas cleaning equipment does not exceed the following: for PM 2.5—89%; PM 1.5—85%; and PM 0.5—76%. The obtained research results made it possible to propose a design for an agglomeration chamber that can greatly increase the productivity of ultrasonic flow processing.
... This indicates that coagulation processes have almost no effect on the disperse composition of the formed droplets. This is due to the fact that the ultrasonic frequency used (22.2 kHz) is significantly higher than that required for coagulation of the formed liquid droplets, and does not engage them with oscillatory motion [30][31][32]. This fact is the subject of future studies. ...
Spraying various liquids (primarily aqueous solutions of various substances) is widely used in various technological processes. For most of them, high dispersibility and narrow droplet size distribution are essential. This facilitates ultrasonic spray technique. However, the higher the dispersity of droplets produced by ultrasonic spray, the lower the spray productivity. To solve this problem, we proposed a method of multistage spraying, consisting in generation of a large number of particles of large initial size (to ensure high productivity) and their subsequent destruction by propagation in a periodic ultrasonic field (to ensure small droplet sizes at high productivity). To experimentally determine the capabilities of this technique, a tubular emitter in the shape of a cylinder of stepped-variable cross-section was designed. Configuration of the ultrasonic field inside the emitter (22.2 kHz; 182 dB) implements three-stage spraying (the number of sputtering stages corresponds to the number of anti-nodes along the emitter axis). The effectiveness of proposed and developed technique suitable for generation of droplets sized less than 40 µm with performance exceeding the known ultrasonic spray techniques at least 10 times has been confirmed in the course of conducted research.
... For these reasons, the low probability of particle collision, especially at low concentrations (large distances between particles) leads to the fact that, even at the maximum permissible sound pressure level (before the destruction of the formed agglomerates), increasing the efficiency of agglomeration of particles smaller than 2.5 μm due to ultrasonic vibrations becomes virtually impossible [19]. ...
... For example, in [19] it was shown that studies of ultrasonic agglomeration were carried out under conditions of detection of high particles in concentrations from 0.2 to 5 g/m 3 . Such conditions are typical during the production of any product and its capture in the form of highly dispersed particles. ...
The article is devoted to the study of ultrasonic agglomeration of PM2.5 in uniform and non-uniform ultrasonic fields. The possibility of increasing the efficiency of ultrasonic agglomeration by initiating acoustic streams in a resonant non-uniform ultrasonic field is shown. A non-uniform ultrasonic field with zones of high and low sound pressure levels formed using a bending-oscillating disk transmitter made it possible to initiate acoustic vortex-type streaming that promote the movement of particles into the nodal areas of a standing wave and between them. The efficiency of ultrasonic treatment was determined indirectly by the degree of inertial trapping of agglomerates. It has been established that the impact of an non-uniform ultrasonic field in comparison with the impact of a uniform ultrasonic field makes it possible to increase the efficiency of inertial capture of agglomerates PM2.5 from 89% to 95%, PM1.5 from 85% to 92%, PM0.5 from 76% to 85%. The results obtained made it possible to propose a design for an agglomeration chamber, which allows for a multiple increase in the productivity of ultrasonic processing of a gas-dispersed flow.
... Coagulation is accelerated in turbulent flows [48], under the action of acoustic waves [49,50], under the combined action of ultrasound and vortex motion. Such a combined effect is successfully studied in the works of Khmelev et al. [51][52][53]. ...
The present review is concerned with the motion of aerosol particles, including that under the exposure to external fields, with special focus being put on the problems related to the similarity theory and invariants that manifest themselves as symmetry in physics. Research on the mechanics of aerosols is extremely important for managing environmental practices. Ultrasonic and electrostatic effects are used in technological processes for cleaning industrial aerosol emissions. In addition, aerosol systems are commonly used to prevent emergency situations (fire extinguishing, fog deposition). Understanding these processes requires knowledge of aerosol mechanics. At the same time, fundamental laws of particulate matter behavior have not been established until now, especially in the presence of external fields. In this paper, we consider the main similarity criteria that are applied for aerosol description. The motion of aerosol particles in the gravitational, electric, and ultrasonic fields is described. The results from studies into acoustic and electrostatic aerosol coagulations are presented herein.
The relevance. The urgent need to deal with fog for preventing limited visibility and creating improved meteorological conditions. Exposure to gas dispersed systems by mechanical vibrations of the ultrasonic frequency can be considered as the most effective way to deal with fog formation. However, the acoustic method has not found an industrial application for fog destruction mainly due to the lack of effective sources of acoustic exposure. Therefore, it is necessary to create emitters of higher power that provide a significantly greater range of radiation with a sound pressure level of at least 140 dB and study of their functionality. The main aim. Determination of the effectiveness of fog destruction through the use of ultrasonic vibrations generated by the developed ultrasonic emitters; identification of the most promising design of ultrasonic equipment that ensures effective destruction of fogs in open areas. Objects. Combining fog droplets under high-intensity ultrasonic exposure using specially designed ultrasonic emitters for gas media of four types. Methods. Experimental method for studying fog droplets combination under the influence of ultrasonic vibrations and their gravitational deposition. To determine the aerosol (water content and disperse composition) characteristics, during experimental studies, the authors have used the TIPAS-1 meter based on the method of small-angle scattering and the method of spectral transparency. Results. The authors established and shown the effectiveness of ultrasonic effect on fogs, as well as the possibility of its use for fog destruction in an open area. All developed disc ultrasonic emitters are capable of forming a sound pressure level within 140... 145 dB at 22±2.0 kHz. The time of fog natural destruction in the aerosol chamber is reduced by up to 11.5 times. The results obtained demonstrate that it is necessary to use more powerful disc emitters, since they can significantly reduce the time of fog destruction and increase the volumes voiced at the same time. The minimum time for establishing the required metrological range of visibility is provided by means of a directional emitter with a stepped-variable surface, forming a flat wave.
