Solid Dust Particles Research Articles

Shock wave kinematics in an inviscid gas with solid dust particles

Shock wave kinematics in an inviscid gas with solid dust particles

Morphology and elemental composition of individual solid dust particles: From different sources to the atmosphere

This study investigates the morphology and elemental composition of individual solid dust particles from various sources (e.g., thermal power plant, domestic coal combustion, building construction dust, wind-blown dust, Asian dust storm, and road related dust) to the atmosphere under high and low relative humidity (RH) conditions in a coastal city of north China by using high-resolution electron microscopes. The results showed that distinct variations between dust particles from thermal power plant and domestic coal combustion, despite both using coal as fuel. Specifically, 88.6% (by number) of thermal power plant particles were spherical, whereas only 2 out of 347 particles from domestic coal combustion exhibited a spherical shape. Furthermore, domestic coal combustion particles showed a higher proportion of Ca-rich particles compared to those from thermal power plant. The wind-blown dust and Asian dust storm particles were mainly “Si + Al” subtype (52.0% v.s. 75.3%) and Si-dominant subtype (16.4% v.s. 11.7%) particles, which were mainly from crustal sources. However, wind-blown dust contained a higher fraction of Ca-rich (11.6%) and Fe-rich (5.3%) particles than Asian dust. The building construction dust particles primarily consisted of irregular Ca-dominant (39.4%) and “Ca + Si” subtype (29.8%) particles. Road related dust were also mainly Si-rich particles (52.9%), likely from re-suspended soil, along with a notable presence of spherical (8.0%) and Fe-rich particles (19.3%), possibly linked to vehicle emissions and brake wear. Additionally, relative number percentage of Na-rich particles and the average weigh ratios of Na in the atmospheric particles were higher than those from all above-mentioned source samples, suggesting that sea-salt related particles might be an important source of the atmospheric dust at the coastal city. The results indicated that Ca-rich particles were significantly modified by S and NaCl particles might lose Cl through heterogeneous reactions under higher RH.

Assessment of regulatory ecosystem services of green plants in urban ecosystems

The article presents the results of research on the assessment of ecosystem services of green tree stands on the territory of the first academic campus of the National University of Kyiv-Mohyla Academy using the MyTree tool. It is a part of the i-Tree tool set developed by the Forest Service of the United States Department of Agriculture (USDA) of the comprehensive program, designed to assess the ecosystem services provided by individual trees or small groups of trees. Research has established that the most important regulatory services were carbon dioxide absorption, microclimate regulation, energy saving, air purification from ozone and sulfur dioxide. Calculations by the MyTree tool show the annual cost of tree planting services on campus and its projected cumulative growth after 20 years. According to the calculations of the MyTree tool, this year’s cost of tree plantation services of the first academic campus of the National University of Kyiv-Mohyla Academy was $847.29, and according to forecasts, after 20 years it will cumulatively increase to $18,895.36. Estimates of the cost of individual components of regulatory ecosystem services are provided. The cumulative estimate over the next 20 years for CO2 sequestration was $4,129.15, which includes the sequestration of 21,963.55 kg of carbon. Air purification for 20 years is estimated at $1,342.66, which includes absorption and neutralization of 656.24 kg of O3, 117.47 kg of SO2, 54.45 kg of NO2, and 34.26 kg of solid dust particles PM2.5. Energy savings are estimated at $10,791.14, which includes energy savings of 100,448.21 kW. The tree species Aesculus hippocastanum (Bitter chestnut), Picea abies (European spruce), Picea pungens (Blue spruce), Betula pendula (Hanging birch) and Ulmus laevis (Smooth elm) provide the highest value of services. The results of this study can be used in the future to improve the planning and management of green areas of the university campus, taking into account the value of their ecosystem services.In general, the study confirmed the importance of monitoring and evaluating the ecosystem services of green spaces in urban ecosystems for making sustainable decisions regarding the development of urban areas, supporting the well-being and health of the population.

Into the thick of it: ALMA 0.45 mm observations of HL Tau at a resolution of 2 au

To comprehend the efficiency of dust evolution within protoplanetary disks, it is crucial to conduct studies of these disks using high-resolution observations at multiple wavelengths with the Atacama Large Millimeter/submillimeter Array (ALMA). In this work, we present high-frequency ALMA observations of the HL Tau disk using its Band 9 centered at a wavelength of 0.45 mm. These observations achieve the highest angular resolution in a protoplanetary disk to date, 12 milliarcseconds (mas), allowing the study of the dust emission at scales of 2 au. We used these data to extend the previously published multiwavelength analysis of the HL Tau disk, constraining the dust temperature, dust surface density, and maximum grain size throughout the disk. We performed this modeling for compact solid dust particles as well as for porous particles. Our new 0.45 mm data mainly trace optically thick emission, providing a tight constraint to the dust temperature profile. We derive maximum particle sizes of $ cm from the inner disk to $ au. Beyond this radius, we find particles between 300 mu m and 1 mm. The total dust mass of the disk is 2.1 J $ with compact grains, and it increases to 6.3 M$_ J $ assuming porous particles. Moreover, an intriguing asymmetry is observed at 32 au in the northeast inner part of the HL Tau disk at 0.45 mm. We propose that this asymmetry is the outcome of a combination of factors, including the optically thick nature of the emission, the orientation of the disk, and a relatively large dust scale height of the grains that is preferentially traced at 0.45 mm. To validate this, we conducted a series of radiative transfer models using the software RADMC-3D. Our models varying dust masses and scale heights successfully replicate the observed asymmetry in the HL Tau disk. If this scenario is correct, our measured dust mass within 32 au would suggest a dust scale height H/R$>0.08$ for the inner disk. Finally, the unprecedented resolution allowed us to probe the dust emission down to scales of a few au for the first time. We observed an increase in brightness temperature inside the estimated water snowline, and we speculate whether this might indicate a traffic-jam effect in the inner disk. Our results show that 0.45 mm observations of protoplanetary disks can be used to robustly constrain the radial profile of their dust temperature. Additionally, the higher optical depths at this wavelength can be used to constrain the vertical scale height of the dust. Finally, these higher frequencies allow us to reach higher spatial resolutions, which have the potential to resolve the region within the water snowline in disks.

Diverse features of dust particles and their aggregates inferred from experimental nanoparticles

ABSTRACT Nanometre- to micrometre-sized solid dust particles play a vital role in star and planet formations. Despite of their importance, however, our understanding of physical and chemical properties of dust particles is still provisional. We have conducted a condensation experiment of the vapour generated from a solid starting material having nearly cosmic proportions in elements. A laser flash heating and subsequent cooling has produced a diverse type of nanoparticles simultaneously. Here we introduce four types of nanoparticles as potential dust particles in space: amorphous silicate nanoparticles (type S); core/mantle nanoparticles with iron or hydrogenized iron core and amorphous silicate mantle (type IS); silicon oxycarbide nanoparticles and hydrogenized silicon oxycarbide nanoparticles (type SiOC); and carbon nanoparticles (type C), all produced in a single heating–cooling event. Type IS and SiOC nanoparticles are new for potential astrophysical dust. The nanoparticles are aggregated to a wide variety of structures: compact, fluffy, and networked. A simultaneous formation of these nanoparticles, which are diverse in chemistry, shape, and structure, prompts a re-evaluation of astrophysical dust particles.

Mitigating dust particle contamination in an afterglow plasma by controlled lifting with a DC electric field

Particle contamination due to plasma processing motivates the design of a method of electrically lifting particles in a time interval after a plasma’s power is turned off. Small solid dust particles have electric charges that are not frozen until a late stage of the plasma afterglow. Beyond that time, before they fall to a surface below and cause defects, particles can be lifted in a controlled manner by applying an appropriate direct-current (DC) electric field, as we demonstrate experimentally. A few milliseconds after an argon plasma’s capacitively coupled radio-frequency power is switched off, a vertical DC electric field is applied. Thereafter, video imaging shows that the falling of the particles is slowed or stopped altogether, depending on the magnitude of the upward electric force.

The growth and decay of nonlinear wave in polytropic reacting gas with small solid dust particles

The aim of this study is to examine the evolutionary process of shock waves along the characteristic path under the effect of dust particles in a polytropic reacting gas. Testing the nature of the governing quasilinear of this system as a coordinate, we reconstruct the governing equations as Bernoulli’s differential equation and obtain the results. The results in the characteristic plane can display a non-linear behavior in the physical plane. It is shown how the reacting gas parameter influences the evolutionary process of the compressive and expansive waves, respectively, in reacting gas flows. Also, it is shown how the existence of dust in reacting gas influences the growth and decay of the compressive and expansive waves. The transport equation leading to the evolution of shock waves is determined and used to derive the condition for the shock formation. The comparative study of the effect of reacting gas parameters and dust particles on the flow patterning and distorting of shock waves for planar, cylindrically and spherically symmetric flows is also performed.

Numeric Investigation of Non-Stationary Dust-Containing Airflow and Deposition of Dust Particles in the Lower Airways

Within creation of the mathematical model to describe the human respiratory system, we accomplished numeric investigation of non-stationary dust-containing airflow as well as dust particle deposition in the lower airways with the real anatomic geometry based on CT scans. Inhaled air is considered a multi-phase mixture of a homogenous gas and solid dust particles. Motion of a basic carrier gas phase is described using the Euler approach. Solid dust particles are a dispersed carried phase, which is described with the Lagrange approach. The k-ω model is used to describe turbulence. We consider non-stationary airflow during calm inhalation. The article presents calculated flow streamlines for the velocity of particles in inhaled air in the lower airways at different moments. We quantified a share of deposited particles (SDP) with various dispersed structure (between 10 nm and 100 µm) and density (1000 kg/m3, 2000 kg/m3, 2700 kg/m3) in the lower airways; the article provides computed motion paths of particulate matter. Solid particle deposition in the airways has different efficiency depending on particle sizes and density. SDP goes down as their sizes and masses decrease. Particle density mostly influences differences in deposition of micro-sized particles (2.5–20 µm): as particle mass and density grow, SDP in the airways also increases. SDP with their diameter being less than 1 µm amounts to approximately 20 % of all the particles that reach the inlet to the trachea. According to the results obtained by numeric modeling, the greatest share of dust particles penetrates the right main bronchus, predominantly the right middle and inferior lobar bronchi. Dust particles are able to induce diseases of the lungs, pneumoconiosis included.

Analysis of the Severe Dust Process and Its Impact on Air Quality in Northern China

Extreme meteorological events can influence air quality. In March 2021, northern China experienced a severe dust event, leading to widespread air quality deterioration. Using reanalysis datasets and station data, we investigate the synoptic weather patterns, dust transport characteristics, and associated impacts on air quality during this event. The results are as follows. (1) The dust event is closely linked to the Mongolian cyclone, providing favorable conditions for dust emission and long-distance transport. (2) The Gobi Desert in Mongolia is the primary source, with dust particles transported from Mongolia to northern China via the northwesterly flow. Dust transport exhibits a complex three-dimensional structure, with the most intense dust transport at approximately 2500 m altitude. (3) The impact of this dust event on air quality was characterized by its remarkable intensity, extensive spatial coverage, and prolonged duration. Additionally, 58.8% of the stations in northern China experienced pollution, 36.3% of them reached severe pollution levels or higher, and 35.9% of the sites experienced more than 12 h of pollution. (4) The visibility at the northern stations near the dust source rapidly decreases due to solid dust particles. In contrast, the southern stations, with higher moisture content, are primarily affected by liquid particles in terms of visibility. After the frontal passage, wet deposition from the precipitation process gradually improves visibility.

Filtration Performance of 3D-Printed Ceramic Pellets: Investigation Using CFD and Computed Tomography

This study demonstrates the potential for computer-aided engineering and additive manufacturing techniques to fabricate protective layer materials with a novel design of filtration channels. Using computational fluid dynamics (CFD) simulation for channels of various geometries, potential locations of the capture of solid dust particles in ceramic filter pellets were identified. The filter pellets were fabricated from ceramic material using laser stereolithography. The printed samples were subjected to a filtration test. The CFD simulation of the pellet channels to identify potential filtration locations, followed by a comparative assessment of the simulation results and the post-test X-ray computed tomography (CT) scan of the 3D-printed pellets, demonstrated the feasibility of CFD models for the design of filter materials. The study findings are intended for the development of innovative protective materials with filtering capabilities to be implemented in specific industrial refining applications

SCIENTIFIC SUBSTANTIATION OF ENVIRONMENTAL MONITORING SYSTEMS AT THE REGIONAL LEVEL USING THE EXAMPLES OF PM2.5, PM10 AND OZONE IN WARTIME CONDITIONS

SCIENTIFIC SUBSTANTIATION OF ENVIRONMENTAL MONITORING SYSTEMS AT THE REGIONAL LEVEL USING THE EXAMPLES OF PM2.5, PM10 AND OZONE IN WARTIME CONDITIONS

Time-Synchronized Microwave Cavity Resonance Spectroscopy and Laser Light Extinction Measurements as a Diagnostic for Dust Particle Size and Dust Density in a Low-Pressure Radio-Frequency Driven Nanodusty Plasma

In a typical laboratory nanodusty plasma, nanometer-sized solid dust particles can be generated from the polymerization of reactive plasma species. The interplay between the plasma and the dust gives rise to behavior that is vastly different from that of pristine plasmas. Two of the key parameters in nanodusty plasma physics are, among other things, the dust particle size and the dust density. In this work, we introduce a novel method for the determination of these two quantities from the measurement of the free electron density using microwave cavity resonance spectroscopy and laser light extinction measurements. When comparing these two measurements to theory, one can determine the best-fitting dust particle size and dust density. Generally, cyclic behavior of the dust particle size and dust density was observed, of which the trends were relatively insensitive to varying the most stringent input assumptions. Finally, this method has been used to explore the behavior of the dust particle size and dust density for varying plasma powers.

Development and validation of a new cloud simulation experiment for lab-based aerosol-cloud studies.

The Aerosol Interaction and Dynamics in the Atmosphere (AIDA) cloud expansion chamber with a volume of 84m3 was extended for the small cloud expansion chamber AIDA mini (AIDAm) with a volume of 20 L. AIDAm is located in the cold room of AIDA and can perform automated ice-nucleation measurements over longer time periods of hours to days. AIDAm samples from the AIDA chamber, which acts as a reservoir of atmospheric aerosol types, which can slowly be modified by physical or chemical processes similar to those occurring in the atmosphere. AIDAm was validated for accurate ice-nucleation temperature control by measuring homogeneous freezing of pure water droplets at temperatures around -34 °C and for immersion freezing induced by dust aerosol particles in the temperature range between -20 and -30 °C. Further validation experiments at cirrus cloud temperatures of -45 °C revealed that AIDAm can distinguish between heterogeneous ice formation on mineral dust aerosols and homogeneous freezing of sulfuric acid solution particles. The contribution of homogeneous and heterogeneous ice formation processes to the ice-nucleation activity of coated dust particles was investigated in a 7 h long experiment, where solid dust particles were slowly coated with sulfuric acid. The continuous AIDAm measurements with a time resolution of 6minshowed a substantial suppression of the heterogeneous freezing phenomenon and an increasing role of homogeneous freezing while the coating amount was slowly increased. This experiment proved the capability of AIDAm to sensitively detect small changes in the ice-nucleation ability of aerosols, which undergo slow processing like chemical surface coating.

STUDY OF SMOKE OF EXHAUST GASES OF INTERNAL COMBUSTION ENGINES OPERATING ON DIESEL FUEL WITH BIOPLE ELEMENTS

The most popular vehicle in the world is the car, their number is constantly increasing. Older cars are being replaced by improved models, and new car designs and systems are being developed and implemented. Areas of improving the design of the car, in addition to improving safety, fuel economy and comfort, include improving environmental safety, as the car is a source of environmental pollution. Internal combustion engines are the main source of man-made air pollution. The operation of the internal combustion engine is accompanied by the formation of emissions of sulfur dioxide and nitrogen oxides, which is the cause of acid precipitation. Smog and the greenhouse effect due to hydrocarbon emissions are inevitable, and solid dust and soot particles cause weather changes (cold, fog and rain). All these factors, together with industrial emissions, are leading to global climate change. Fuel evaporation, crankcase and exhaust gases are among the main phenomena of harmful effects of the internal combustion engine on the environment and account for up to 78%. This article highlights the problem of soot formation in the soot filters of the car exhaust system. Groups of chemical elements that are part of exhaust gases are considered. The existing directions of reducing the toxicity of exhaust gases are analyzed. The influence of different types of fuel on the toxicity of exhaust gases and soot formation is determined. The principle of soot filter operation during filtration and regeneration is described. Types of regeneration and the principle of their action are described. Smoke of soot filters at different mileage was studied. The principle of using the Infracar D smoke meter is described. An experimental study of ultrasonic soot filter cleaning was performed. Based on the information received, conclusions are drawn.

Characterization of cyclic dust growth in a low-pressure, radio-frequency driven argon-hexamethyldisiloxane plasma

In a dusty plasma, nanometer-sized solid dust particles can be grown by the polymerization of plasma species from a reactive precursor gas. This type of plasma can be found in large-scale astrophysical objects, as well as in semiconductor manufacturing and material processing. In a laboratory environment, the plasma parameters can be carefully controlled and the dynamics of dust growth as well as the interaction between the plasma and the dust can be studied. In this work, we investigate the cyclic growth of dust particles in a low-pressure, radio-frequency driven argon-hexamethyldisiloxane plasma using a multitude of diagnostics in a time-synchronized fashion. The combination of microwave cavity resonance spectroscopy, plasma impedance measurements, laser light scattering, laser light extinction measurements and optical emission spectroscopy offers a broad view on the temporal behavior of the plasma in concert with the plasma-grown dust particles. We have studied the variation of several discharge parameters such as plasma power and hexamethyldisiloxane content. Therefore, this multi-diagnostic approach contributes to the fundamental understanding of the mechanisms behind dust growth in low-pressure plasmas.

Propagation of shock wave in a non-ideal dusty gas in rotating medium using Lie group theoretic method: Isothermal flow

This paper concerns with the similarity solutions using Lie group theoretic method for one-dimensional unsteady isothermal flow behind the shock wave in the mixture of non-ideal gas and small solid particles in rotating medium. Group theoretic technique brings the different possible cases of potential solutions with the power law, particular case of power law and exponential law shock paths with the different choices of constants present in the generators of the Lie group of transformations. Similarity solutions for non-ideal dusty gas (a mixture of non-ideal gas and small solid dust particles) exist if the density of the ambient medium is constant. Solutions are obtained for both exponential law and power law shock paths. The effects of the variation of the physical parameters on the flow variables distribution behind the shock wave front, and on the shock are discussed. The shock strength increases with an increase in the ratio of the specific heat of the solid particles to the specific heat of the gas at constant volume [Formula: see text], the initial azimuthal velocity variation index [Formula: see text], and the ratio of the density of solid particles to the initial density of the gas [Formula: see text]. The shock wave decays with an increase in the value of gas non-idealness parameter [Formula: see text].

Spatial distribution of aerosol and dust man-made emissions in external influence zone of metallurgical enterprises

The study presents the method for calculating the distribution of dust and aerosol particles entering the external air environment as a result of man-made emissions of metallurgical cycle enterprises. The paper proposes the method for predicting the degree of pollution of the enterprises influence zones by constructing geographical maps-schemes of industrial regions with application of the areas with a high content of dust particles on them. This method is based on determination of the sedimentation time of dust particles of different fractions in atmospheric air using Stokes’ law (motion of solid particles in liquid or gaseous media), the height of dust particles departure from the chimney and the speed of prevailing wind over the studied period of time. The data necessary for the analysis (wind direction, amount of dust emitted, its fractional and chemical compositions) were found in open sources, reports of the enterprise, statistical data of the region and the metallurgical industry. An estimated calculation of the spread of dust emissions was carried out on the example of the Magnitogorsk Iron and Steel Works PJSC (MMK) during various annual seasons. It was found that the influence of activity of a metallurgical enterprise in Russia can adversely affect cities and residents of neighboring states that are located in the sedimentation zone of solid dust particles. The issue of transfer of sulfuric and nitric acids by dust particles formed in the pores of aerosol particles is considered. The authors calculated the amount of acid that can be carried into the zones of influence of the enterprise in the pores of solid dust particles. The considered calculation model makes it relatively quick and easy to assess the influence zone of the enterprise, assess risks and take measures to modernize, optimize the production process or aspiration systems.

On the evolution of magnetic shock wave in the mixture of gas and small solid dust particles

The paper aims to analyze the evolutionary behavior of weakly nonlinear waves propagating in one-dimensional unsteady flow of perfectly conducting compressible fluid subjected to a transverse magnetic field with dust particles. The method of progressive wave approach is utilized to determine the evolution equation characterizing the propagation of wave and also obtained the condition for first wave breaking at finite time. Further, we analyze the behavior of acceleration wave propagating in the medium considered. Also, the propagation of disturbances in the form of sawtooth wave (half N-wave) is studied here. It is observed that the presence of mass fraction of solid particles (kp) and β both causes to slow down the decay process. Also, the effect of axial magnetic field is to increase the growth rate of sawtooth wave (Half N-wave) as compared to in the absence of axial magnetic field. Further, the effect of magnetic field is to slow down the decay process in the presence of mass fraction of solid particles (kp).

Mathematical Model of Airflow and Solid Particles Transport in The Human Nasal Cavity

As part of the mathematical model of the human respiratory system, a submodel is considered for the study of the non-steady airflow with solid particles (suspended particulate matter (PM) / dust particles) and the deposition of particles of various sizes in the human nasal cavity. It is assumed that the nasal cavity is divided by the bone-cartilaginous septum into two symmetrical (relative to the nasal septum) parts; the average geometry of the right part of the human nasal cavity is considered. The inhaled air is considered as a multiphase mixture of homogeneous single-component gas and solid dust particles. The Eulerian-Lagrangian approach to modeling the motion of a multiphase mixture is used: a viscous liquid model is used to describe the motion of the carrier gas phase; the carried phase (dust particles) is modeled as separate inclusions of various sizes. The process of heating the inhaled air due to its contact with the walls is also taken into account. The features of the unsteady flow of a multiphase air mixture with dust particles were obtained using Ansys CFX for several scenarios. It has been noted that when studying the airflow in the nasal cavity, it is necessary to take into account the presence of turbulence, for which it is proposed to use the k-ω model. The velocity fields of inhaled air in the nasal cavity have been obtained; presented temperature distributions in the nasal cavity at different time points; made estimates of air heating at different temperatures of inhaled air; gave estimates of the proportion of deposited particles in the nasal cavity depending on the particle size for real machine-building production; presented trajectories of movement of suspended particles. Thus, it is shown that more than 99.7 % of particles with a diameter of more than 10 microns deposit in the human nasal cavity; as the particle diameter and mass decrease, the proportion of deposited particles decreases. Suspended particles with a size of less than 2.5 microns almost do not deposit in the nasal cavity. They can penetrate deeper into the lower airways and lungs of a person with the inhaled air and, having fibrogenic and toxic effect, can cause diseases. The results obtained are in good agreement with the results of individual studies performed by other scientists. Further development of the model involves studying airflow in the human lungs and modeling the formation of diseases caused by the harmful effects of environmental factors (including dust particles) entering the human body by inhalation.

Contribution of leading edge shape to a damaging of castellated tungsten targets exposed to repetitive QSPA plasma loads

The castellated tungsten monoblock is considered one of the preferred reference designs of components faced to plasma in the divertor of a fusion reactor. The behavior of such components during the development of transient events (disruptions or/and of Edge Localized Modes (ELMs)) is still among the most critical issues for future thermonuclear devices. Experimental studies of castellated tungsten surface erosion have been performed within the powerful quasi-stationary plasma accelerator QSPA Kh-50 in conditions relevant to unmitigated ITER Type I ELMs. The surface energy load from the impacting hydrogen plasma streams was 0.9 MJ m−2 during 0.25 ms to achieve pronounced melting of the target surface. The studies of solid and liquid particle generation were performed at sequentially oblique plasma exposure of the different chosen edges of the castellated structure. It was determined that most of the W droplets are ejected from the sharp leading edge of the target due to the development of instabilities in the plasma-liquid metal interface. At the same time, the formation of solid dust particles is mainly attributed to the cracking during the surface cooling after the plasma pulse. Particle velocities typically achieve tens m s−1. Both the re-solidified droplets as well as dust particles have been collected on the special plate near the exposed surface. The maximal size of collected particles reached tens of micrometers. Such particles could either fly away with the next plasma pulses or mix with the material of the collecting plate in the course of repetitive plasma pulses. Thin (submicron) layers of re-deposited tungsten also formed on the surface of the collecting plate.