High Dust Research Articles

Decoupling of dust cloud and embedding plasma for high electron depletion in nanodusty plasmas

In recent years nanoparticles have become key technological products, e.g., as coatings with tunable optical gap in third generation solar cells, as nanocrystals for photonic applications, and as pharmaceutical nanocarriers. In particle sources, that use reactive, nanodusty plasmas, a high dust density changes the properties of the dusty plasma compared to a dust free plasma considerably, as electron depletion leads to a reduced number of free electrons. This is called the Havnes effect and was central for the understanding of the famous spokes in Saturns rings. We see here, that it is also important for technological applications. Using self excited dust density waves (DDW) as a diagnostic tool, we completely characterize an argon discharge with embedded amorphous hydrocarbon nanoparticles of different size and density. The results show, that electron depletion governs the charge of dust grains, while the size of the particles has only a weak influence. The ion density and electric potential profile are almost independent of both, dust size as well as dust density. This suggests, that the rf generated plasma and the dust cloud seem to coexist and coupling of both is weak.

Measurement report: The Urmia playa as a source of airborne dust and ice-nucleating particles – Part 1: Correlation between soils and airborne samples

Abstract. The emergence of desiccated lake bed sediments and their exposure to wind erosion as a consequence of climate change and drought in arid and semiarid regions of the world poses a growing hazard. Airborne dust originating from such soils can create health and environmental issues due to their high salt content and the presence of toxic elements. The aim of the present study is twofold, namely to investigate the newly emerged playa surfaces of western Lake Urmia (LU) in Iran and their contribution to aerosol in the region by means of physicochemical, mineralogical, and elemental analyses and to study the ice nucleation (IN) activity of both surface-collected soil and airborne dust samples. The playa surfaces created by desiccation of LU on the western shores were mapped and sampled at 130 locations. Soil samples were subjected to physicochemical analyses, and their erodible fraction was determined. Based on these analyses, four highly erodible playa surfaces from the northwest to the south of LU were selected as sites for collection of dust by impaction and soil samples from the uppermost surface. Their particle physicochemical properties (size distribution, elemental and mineralogical composition) were compared with their IN activity determined by emulsion freezing experiments in a differential scanning calorimeter (DSC) in two suspension concentrations of 2 wt % and 5 wt %. The physicochemical soil properties differed significantly between the different playa surfaces, which affects their susceptibility to wind erosion. Sand sheets and sandy salt crusts were the most erodible playa surfaces due to their high sand fraction and low organic matter and clay content, favouring the presence of small aggregates. Mineralogical analyses document the prevalence of quartz, carbonates, and clay minerals, such as kaolinite, palygorskite, and chlorite in all of the samples. The predominant elements in the samples are Ca, Fe, Al, Si, and Na (and in some cases Ba, Sr, and Zn). The correlation between soil and dust samples based on mineralogical composition, elemental enrichment factors, and physicochemical properties confirm that the playa surfaces are the major contributors to dust in the region. IN activity with onset temperatures ranging from 245 to 250 K demonstrates the high potential of dust blown from Urmia playa surfaces to affect cloud properties and precipitation. Freezing onset temperatures and the fraction of heterogeneously frozen droplets in the emulsions reveal variations in IN activity depending on the mineralogical composition of the samples but which are also influenced by organic matter, salinity, and pH. Specifically, IN activity correlates positively with organic matter and clay minerals and negatively with pH, salinity, and (surprisingly) K-feldspar and quartz content. The high wind erodibility and dust production of the LU playa surfaces together with their high IN activity can play an important role in the climate of the region and thus needs careful monitoring and specific attention.

Modernization of hopper car for transportation of agglomerate and other materials

The paper considers results of the analysis of operability of the transporting equipment at agglomeration shops of the Ural metallurgical enterprises. It was established that during long-term operation of the hopper car for transportation of hot agglomerate, dust settles on its walls, growths of accumulated dust are formed, and the effect of vaulting occurs. Due to compaction and increase in dust layer, useful volume of the hopper car decreases which in turn leads to the need to carry out dangerous work to clean the dust directly inside the hopper car. Manual labor is used for this purpose. Such works are very dangerous for human health due to high dust content and high injury risk. In order to eliminate the problem of vaulting and accumulation of dust on the car walls, it is proposed to use the installation of two vibrating devices of the “False wall” type together with a vibrating neck (vibrating beam). The vibrating element of the device is a plate that is mounted on the inner wall on flexible suspensions (round link chain). Rubber shock absorbers are installed between the plate and the hopper wall, which are used as rubber-fabric conveyor belt. A vibrator is mounted to the plate through the support post, and the transmission of vibrations to the agglomerate is carried out using a vibrating hump, which is welded to the plate (false wall). Introduction of the designed device ensures reduction of unplanned downtime of the hopper cars team and rejection of hazardous to human health work related to the bunkers cleaning. The economic calculation confirms feasibility of the ongoing measures for reengineering of hopper cars in the conditions of agglomerate production at metallurgical enterprises.

Spatio-temporal changes of spring-summer dust AOD over the Eastern Mediterranean and the Middle East: Reversal of dust trends and associated meteorological effects

High dust concentrations in the Eastern Mediterranean - Middle East (EMME) region have serious effects on air quality, human health and climate. This study used long-term aerosol datasets during the main dusty season (April–July: AMJJ) over the EMME from 2000 to 2020, based on Moderate-Resolution Imaging Spectroradiometer (MODIS)/Terra-C6.1, Modern-Era Retrospective Analysis for Research and Applications version 2 (MERRA-2), and Copernicus Atmosphere Monitoring Service Reanalysis (CAMSRA) retrievals and analyzed the spatio-temporal variations and trends of dust, as well as the influencing factors. The dust aerosol optical depth (DAOD) experienced a significant upward trend during 2000–2010, followed by a significant decrease during 2010–2017. After 2017 and till 2020, the DAOD presented rather a stable trend. Aerosol Robotic Network (AERONET) data in the EMME region display trends compatible to those of both MERRA-2 and CAMSRA DAOD. The DAOD trends were linked to changes in regional meteorological parameters in the EMME. A significant downward trend in AMJJ sea-level pressure (SLP) during the early period (2000−2010) induced hot and dry winds from desert regions towards the EMME, which reduced relative humidity (RH) and raised temperature, thus favored soil drying and dust outbreaks through enhancing evaporation. In contrast, a significant increase in winter SLP during the late period (2010–2017), accompanying an increase in North Atlantic Oscillation index, induced cold, wet winds from northwest regions, which increased RH and lowered temperature, thus reducing dust loading in EMME. Positive anomalies in winter soil moisture persisted in the following AMJJ, and consequently suppressed dust activity. DAOD variability over the dust-prone regions was linked to various meteorological parameters via a multiple linear regression (MLR) model. The results show that climatic variability strongly affects the dust trends and contribute to better understanding of meteorological – dust dynamics in the EMME region.

Pose Measurement Technology of Roadheader Body based on Fusion of Visual and SINS*

In order to solve the problem of pose measurement of roadheader body in low illumination and high dust environment in coal mine, a pose measurement technology of roadheader body based on visual and strapdown inertial navigation system (SINS) is proposed. By extracting the point and line features and using the monocular vision positioning principle based on the gate three lines, the spatial pose of the roadheader body measured by vision is obtained according to the spatial matrix transformation. At the same time, the spatial pose of the roadheader body measured by SINS is calculated by gyroscope and accelerometer. Then the least square method is used to align the two-sensor data, and the registration data is fused based on the extended Kalman filter fusion algorithm to obtain the final fusion roadheader pose data. The experimental results show that the measurement error of the roadheader body position in the x axis direction of the roadway coordinate system is less than ± 20 mm, the error of the y axis direction is less than ±35 mm, the error of the z axis direction is less than ± 10 mm, the yaw angle error is between-0.4° to 0.7°, the roll angle error is between -0.2° and 0.6°, and the pitch angle error is between -0.02° and 0.5°. This method can be used to measure the pose of the roadheader stably and accurately in the complex environment of high dust, miscellaneous light and low illumination.

System Design of Temperature Measurement and Sampling Robot in Steel Plan

In the traditional steel-making production process, the workers use a 20kg temperature measuring gun to insert into the ladle with more than 1500 degrees Celsius for temperature measurement and sampling. Each furnace must take the temperature at least 4 to 6 times, with sampling 3 to 5 times. The labor intensity is heavy. Due to the high temperature and dust at the furnace’s mouth, the environment is bad, and there are unforeseen emergencies such as molten steel explosion, which has a large potential safety hazard. Therefore, using industrial robots’ temperature measurement and sampling can reduce the labor intensity of workers and improve safety factors. This paper studies and designs the temperature measurement and sampling robot system in the steel plant, in order to avoid manual temperature sampling. Using industrial robots as the platform, using SolidWorks software to model and build the system. The path planning and simulation of the temperature measurement sampling robot is conducted through Robot Studio software, and then Adams software is used to conduct the dynamic simulation analysis, the results show the motion of the robot after visual simulation and obtain the dynamic parameters and verify the reasonable feasibility of the path.

A First Look into the Nature of JWST/MIRI 7.7 μm Sources from SMACS 0723

Until now, our knowledge of the extragalactic universe at mid-infrared (mid-IR) wavelengths (>5 μm) was limited to rare active galactic nuclei and the brightest normal galaxies up to z ∼ 3. The advent of JWST with its Mid-Infrared Instrument (MIRI) will revolutionize the ability of the mid-IR regime as a key wavelength domain to probe the high-z universe. In this work we present a first study of JWST MIRI 7.7 μm sources selected with >3σ significance from the lensing cluster field SMACS J0723.3-7327. We model their spectral energy distribution (SED) fitting with 13 JWST and Hubble Space Telescope broad bands, in order to obtain photometric redshifts and derived physical parameters for all these sources. We find that this 7.7 μm galaxy sample is mainly composed of normal galaxies up to z = 4 and has a tail of about 2% of sources at higher redshifts to z ≈ 9–10. The vast majority of our galaxies have [3.6]–[7.7] < 0 colors and very few of them need high dust extinction values (A V = 3–6 mag) for their SED fitting. The resulting lensing-corrected stellar masses span the range 107–1011 M ⊙. Overall, our results clearly show that the first MIRI 7.7 μm observations of deep fields are already useful to probe the high-redshift universe and suggest that the deeper 7.7 μm observations to be available very soon will open up, for the first time, the epoch of reionization at mid-IR wavelengths.

OPPS Fibers with High Temperature Resistance and Excellent Antioxidant Properties by an Oxidation Method.

Polyphenylene sulfide (PPS) fiber products have been widely used for separation and filtration in harsh environments due to their excellent chemical resistance and relatively economical price. However, the poor temperature and weak oxidation resistance of PPS significantly shorten its service life under high temperature and strong oxidation environments. Herein, we report a type of oxidation-modified PPS (OPPS) fibers with excellent high temperature and oxidation resistance. This is achieved by oxidizing the thioether sulfide groups in PPS molecular chains into sulfoxide and sulfone groups and cross-linking the intermolecular chains. Both experiments and density functional theory (DFT) calculations indicate that hypochlorous acid (HClO) molecules can rapidly oxidize the PPS fiber surface. In addition, molecular dynamics (MD) simulations prove that there are strong hydrogen bonds and van der Waals interactions between HClO molecules and OPPS molecular chains, which promote the penetration of HClO molecules into the interior of the fiber to complete the layer-by-layer oxidation. The prepared OPPS-20 fibers exhibit excellent structural stability under high temperature and strong oxidant environments. Impressively, the OPPS-20 nonwoven filter still exhibits a high dust filtration efficiency of 99.95% after aging at 320 °C for 12 h, and the corresponding pressure drop is 24 Pa. In addition, the OPPS-20 nonwoven filter also maintains excellent filtration performance after aging in 60% HNO3 solution for 12 h, and the filtration efficiency and pressure drop are 99.96% and 29 Pa, respectively. This work demonstrates that the novel OPPS fibers have excellent application prospects in the field of separation and filtration in harsh environments.

Prolonged Drought Enhances Northwest China Dust Storm Activity

AbstractThe patterns and forcing mechanism of dust storms in arid Northwest China remain unclear and debated due to lack of reliable long‐term geological records. Here we present a ∼1,600‐year dust storm history in Northwest China based on the sedimentary coarse fraction (&gt;63 μm) retrieved from Lake Hurleg and Lake Qinghai on the northeastern Tibetan Plateau (NETP). The NETP dust storm history, which agrees well with those from North China, shows two prolonged intervals of high dust storm occurrences during the Medieval Warm Period and the past century, and two prolonged weakened dust storm intervals from ∼400 to 700 CE and during the Little Ice Age. The temporal variation in NETP dust storm activities is out‐of‐phase with moisture records over central Asia, with enhanced dust storms corresponding to warm‐dry intervals, and vice versa. The prolonged centennial warm‐dry climates over arid Northwest China to arid central Asia could have led to decreased soil moisture, deteriorated vegetation cover, and increased dust particle supply and dust storm activities; while the prolonged centennial cold‐wet climates could have increased soil moisture, vegetation cover, and decreased dust storm activities. We contend that whilst human impact could be responsible for the obviously increased eolian dust flux in the most recent century, it is most likely that the prolonged natural hydroclimatic conditions regulate the global dust storm activity before the Anthropocene.

Review of Filters for Air Sampling and Chemical Analysis in Mining Workplaces.

This review considers the use of filters to sample air in mining workplace environments for dust concentration measurement and subsequent analysis of hazardous contaminants, especially respirable crystalline silica (RCS) on filters compatible with wearable personal dust monitors (PDM). The review summarizes filter vendors, sizes, costs, chemical and physical properties, and information available on filter modeling, laboratory testing, and field performance. Filter media testing and selection should consider the characteristics required for mass by gravimetry in addition to RCS quantification by Fourier-transform infrared (FTIR) or Raman spectroscopic analysis. For mass determination, the filters need to have high filtration efficiency (≥99% for the most penetrable particle sizes) and a reasonable pressure drop (up to 16.7 kPa) to accommodate high dust loading. Additional requirements include: negligible uptake of water vapor and gaseous volatile compounds; adequate particle adhesion as a function of particle loading; sufficient particle loading capacity to form a stable particle deposit layer during sampling in wet and dusty environments; mechanical strength to withstand vibrations and pressure drops across the filter; and appropriate filter mass compatible with the tapered element oscillating microbalance. FTIR and Raman measurements require filters to be free of spectral interference. Furthermore, because the irradiated area does not completely cover the sample deposit, particles should be uniformly deposited on the filter.

A neural networking based fault detection system for pitch and yaw control of a HAWT under different operating conditions

A fault detection system for the pitch and yaw control of a 1.5 MW horizontal axis wind turbine based on a data-driven technique is proposed. The impact of high ambient temperature and dust accumulation on the proposed fault detection technique was investigated. The system was modeled using the simulation programs FAST, TurbSim, and MATLAB under various operating scenarios and wind speeds. Pitch angle faults from −10° to 15°, blade imbalance faults from −3% to 7%, and nacelle-yaw angle faults from −10° to 20° were investigated. Furthermore, fault detection was considered under different operating temperatures. The Fast Fourier Transform (FFT) was applied to the Tower Top Deflection (TTD) data. Results show that the peaks of the TTD while applying faults to the blade are in the range of 5.09 to 21.42 Hz. YAW faults produce a single peak at 5.67 Hz while blade faults have two peaks. Moreover, the ambient temperature affects both the frequency and amplitude spectrum values. The TTD data were utilized to develop a Neural Network that can identify the errors in the pitch and yaw control systems. This network categorizes the faults into three categories with a best validation performance of 0.0086482.

Eurasian Ice Sheet derived meltwater pulses and their role in driving atmospheric dust activity: Late Quaternary loess sources in SE England

The role of Quaternary ice sheet fluctuations in driving meltwater pulses and ocean circulation perturbations is widely acknowledged. What is less clear is the role of these processes in driving changes in past atmospheric dust activity, and possible wider links between dust and climate. Terrestrial windblown dust (loess) deposits along the northern fringe of the European loess belt potentially record past atmospheric dust emission from regions close to the former Eurasian Ice Sheet (EIS) and provide a means to evaluate the role of ice sheet fluctuations in the past dust cycle. Numerical loess chronologies across this region generally agree on greatly enhanced dust deposition rates during MIS 2, when the EIS reached its maximum extent. Yet, uncertainties over the sources of this material prevent understanding of the precise causes of this greatly enhanced atmospheric dustiness, and any potential link to ice sheet fluctuations and climate. In southeast England, loess accumulation dominantly occurred in two phases centered on 25–23.5 ka and 20–19 ka, matching the timing of coalescence of the Fennoscandian and British-Irish ice sheets and specifically advances and retreats of nearby ice lobes in the western North Sea. As such, these deposits provide an ideal test of the role of ice sheet fluctuations in atmospheric dust dynamics. Here we undertake such a test through a detailed provenance study of loess in southeast England and potential dust source sediments across the North Sea region. We group extensive new and published data sets of detrital zircon U–Pb ages from basement rocks and Cenozoic sediments in the North Sea area, which not only provide new insight into both loess source, but also the nature of sediment transport over NW Europe into the North Sea basin more widely. Multi-proxy evidence allows us to unambiguously identify ice sheet derived sediments in the exposed North Sea basin as the dominant source of loess in southeast England, while fluvial sediments delivered by rivers draining Continental Europe possibly contributed additional source material to the first loess accumulation phase. We propose that sudden retreats of the North Sea Lobe released substantial amounts of sediment rich meltwater into the southern North Sea and Channel basins, driving accelerated dust emission, loess deposition and provenance variability in NW Europe during MIS 2. Moreover, we propose that this model of dust activity driven by proglacial sediment availability may be applicable for EIS marginal regions more widely, even where resultant loess cover is rarely preserved due to extensive erosion and reworking along the ice marginal spillway. This implies the role of ice sheets in controlling wider dust emission may be underestimated. In addition to driving changes in ocean circulation through meltwater pulses, ice sheet dynamics in the Quaternary may have also driven substantial and abrupt changes in atmospheric dust activity. This mechanism may in part explain the coupling between dust and climate events widely seen in Quaternary dust sediment records and suggests a possible major role of high latitude dust emission in MIS 2 dustiness across Europe and beyond.

Limnological Investigations of Sewage Stabilization Ponds at Sewage Treatment Plant in Bikaner (NW Rajasthan)

Abstarct: Geographically Bikaner has four natural slopes, one towards the vallabh garden area, where the three anaerobic and two aerobic stabilization ponds of sewage treatment plant are situated in the North –West part of the Rajasthan. The Thar desert lies which is characterized by typical arid conditions like scarcity of water, low rainfall, intense radiations, violent winds, high temperature fluctuations and dust storms. This paper is based on the chemical limnological study of three anaerobic and two aerobic stabilization ponds of sewage treatment plant. The study was carried out for a period of 15 months from March 2010 to May 2011. The chemical parameters measured include pH, EC (electrical conductance), TDS (total dissolve solids), and Free CO2. The parameters of three anaerobic stabilization ponds of water was ranged pH (6.7 to 8.2), EC (1.5 mmhos/cm to 2.0 mmhos/cm), TDS (960 mg/l to 1280 mg/ l), Free CO2 (172 mg/l to 294 mg/l) and two aerobic stabilization ponds of water was ranged pH (7.3 to 8.4), EC (1.3 mmhos/cm to 1.8 mmhos/cm), TDS (832 mg/l to 1152 mg/ l) and Free CO2 (152 mg/l to 270 mg/l) were recorded.

A Global-Scale Mineral Dust Equation.

A robust method to estimate mineral dust mass in ambient particulate matter (PM) is essential, as the dust fraction cannot be directly measured but is needed to understand dust impacts on the environment and human health. In this study, a global-scale dust equation is developed that builds on the widely used Interagency Monitoring of Protected Visual Environments (IMPROVE) network's "soil" formula that is based on five measured elements (Al, Si, Ca, Fe, and Ti). We incorporate K, Mg, and Na into the equation using the mineral-to-aluminum (MAL) mass ratio of (K2O+MgO+Na2O)/Al2O3 and apply a correction factor (CF) to account for other missing compounds. We obtain region-specific MAL ratios and CFs by investigating the variation in dust composition across desert regions. To calculate reference dust mass for equation evaluation, we use total-mineral-mass (summing all oxides of crustal elements) and residual-mass (subtracting non-dust species from total PM) approaches. For desert dust in source regions, the normalized mean bias (NMB) of the global equation (within ±1%) is significantly smaller than the NMB of the IMPROVE equation (-6% to 10%). For PM2.5 with high dust content measured by the IMPROVE network, the global equation estimates dust mass well (NMB within ±5%) at most sites. For desert dust transported to non-source regions, the global equation still performs well (NMB within ±2%). The global equation can also represent paved road, unpaved road, and agricultural soil dust (NMB within ±5%). This global equation provides a promising approach for calculating dust mass based on elemental analysis of dust.

Uptake of Hg0(g) on TiO2, Al2O3, and Fe2O3 Nanoparticles: Importance in Atmospheric Chemical and Physical Processes.

Mineral dust aerosols play an important role in tropospheric chemistry and aerosol-cloud interaction processes. Yet, their interactions with gaseous elemental mercury (Hg0(g)) are not currently well understood. Using a coated-wall flow tube (CWFT) reactor, we measured the uptake of Hg0(g) on some common components of mineral dust aerosols, including TiO2, Al2O3, and Fe2O3, and the effects of irradiation (dark, visible and UV-A) and relative humidity (<2% to 60%) on the uptake kinetics. Under UV-A irradiation (320-400 nm) in dry air, we measured uptake coefficients (γ) equal to >1 × 10-3 and (3 ± 1) × 10-6 on TiO2 and Al2O3, respectively. Under visible light irradiation (380-700 nm), Hg0(g) uptake was only observed on TiO2, with γ = (4 ± 3) × 10-4. Raising the relative humidity inhibited the uptake on both TiO2 and Al2O3, and the uptake coefficient at 60% RH for TiO2 under UV-A irradiation was lower by ca. 3 orders of magnitude than dry conditions. Furthermore, we observed that water vapor induced the desorption of two distinct fractions from Hg-exposed surfaces via the displacement of weakly, physisorbed Hg and the photocatalyzed reduction of chemisorbed Hg. Based on the uptake coefficients from this report, we estimate that heterogeneous interactions with mineral dust may be significant under conditions with low relative humidity (<30%) and high dust loading masses. We herein discuss the implication of this study on understanding the life cycle analysis of atmospheric mercury in nature.

Synergistic experimental investigation of the nano-ceramic cover sheet on the PV module performance

Due to the accumulation of the heat on surface of the photovoltaic collector as well as the module’s components, the efficiency of photovoltaic (PV) module is influenced by the increase of temperature in particular at high load (high voltage). Therefore, the efficiency and the current output decrease dramatically, and the full performance of the module tends to be zero in these conditions. In the present work, an experimental comparison between a controlled active water-cooling system and nano-ceramic cover sheet system is performed to get the best performance in high load. Water-cooling system is designed to minimize this effect of the high temperature and dust on the photovoltaic module. In addition, the nano-ceramic cover sheet is installed on the module to reduce the infrared permeability. Furthermore, Experiments were performed on the plain module without active cooling or nano-ceramic cover. After the experimental comparison, the results indicated that the controlled active water-cooling system is extremely improve the performance on the contrary the nano-ceramic cover sheet system which reduces the performance.

Group velocity of obliquely propagating Alfvén waves in a magnetized dusty plasma

ABSTRACT In this work, we investigate the characteristics of the group velocity of obliquely propagating Alfvén waves in a dusty plasma typical of a stellar wind. The dispersion relation is derived with the aid of the kinetic theory for a magnetized dusty plasma consisting of electrons and ions, with distribution of momenta described by a Maxwellian function. The dust particles are considered to be immobile and have all the same size; they are electrically charged by absorption of plasma particles via inelastic collisions and by photoionization. We numerically solve the dispersion relation and calculate the components of group velocity (along and transverse to the magnetic field) for the normal modes, namely the compressional and shear Alfvén waves (CAW and SAW). The results show that the direction of the group velocity of CAWs is greatly modified with the wave-vector direction. On the other hand, SAWs will present group velocity propagating practically along the magnetic field. The changes in dust parameters, such as number density and equilibrium electrical charge, may significantly change the waves’ characteristics. It is seen that for sufficiently high dust to ion number density ratio, the SAWs may present perpendicular group velocity propagating in opposite direction to the perpendicular phase velocity, in a small interval of wavenumber values; we also notice that this interval may change, or even vanish, when the flux of radiation incident on the dust is altered, changing the equilibrium electrical charge of the grains.

The Complexity in Dust Charging Process With Relativistic OLM Theory

The ability to self-organization is one of the important features of complex systems that is considered in the process of dust particle charging in space plasmas. The dust grain charging process is considered by the orbital-limited motion theory (OLM) theory with help of the relativistic kappa distribution, the relativistic cross section, and the kinetic model. It is indicated that the critical areas have unique properties that show the complexity in dusty plasma systems. In these areas, the Coulomb force between dust grain and plasma particle plays an important role and has a great influence on the charging process of dust grains. It is obtained that by increasing the electron-to-ion temperature ratio in the high dust grain densities, the relativistic effects increase and the electric potential of dust grain decreases. Moreover, it is indicated that by moving away from thermodynamic equilibrium (Maxwellian), the system tends to form multicomponent plasma more. As another result, the electric potential of the dust grain is much more affected by the nonextensive degree of the electron than the ion. Finally, it is observed that with the increase of dust grain density, the transition from dust in plasma to dusty plasma occurs and multicomponent plasma is formed.

Effect of bubble cutting on spray characteristics and dust control performance in the effervescent atomization

Effervescent atomization performance depends on the bubble size inside the mixing chamber, consequently influencing the spray dust control performance. This paper proposes an optimization of atomization quality and dust control performance by incorporating a bubble cutter in the atomizer mixing chamber. The effects of the bubble cutter aperture on spray characteristics and flow characteristics were experimentally investigated under different operating conditions. Experimental results showed that Sauter means diameter (SMD) decreases with increasing injection pressure and gas-liquid mass flow ratio (GLR). Furthermore, SMD initially increased and then decreased by reducing the aperture of the bubble cutter from 500 µm to 80 µm. In particular, high injection pressure (Pi =0.6 MPa) and low gas-liquid mass flow ratio (GLR=0.09) strengthened the effects of the bubble cutter aperture on SMD. Moreover, bubble cutter causes a contiguous concentrated droplet size distribution, but it has little effect on droplet velocity. Ultimately, the optimal bubble cutter aperture on the efficiency of respirable dust control efficiencies was theoretically calculated. The dust control efficiency is a maximum at the bubble cutter with an aperture of 230 µm for the effervescent atomizer in this paper. Spray dust control efficiency reaches 93.15 %, which effectively solves the problem of high dust concentration pollution in the mechanized working environment.

Influence of seasonal effect on dust accumulation on Photovoltaic panels that operate light posts

Dust accumulation on Photovoltaic (PV) panels is a severe threat that decreases the energy production of PV panels and therefore, lowers their efficiency especially in the Middle East and North Africa (MENA) region. Cleaning of the PV panels has always been a challenge for most of the countries in this region due to scarcity of water resources and high dust accumulation rates throughout the year. A new dust mitigation technique has been developed in this research, which consists of a wind shield, antistatic hydrophilic coating and a mechanical vibrator. The objective of this research is to study the seasonal effects on the performance of this new dust mitigation technique for PV panels that operate street light posts. Two experiments were conducted for six weeks in 2021; the first one was in winter while the other one was in summer. In both experiments, two PV panels were examined. The first PV panel is used as a reference panel for comparison and the second panel is provided with a wind shield and a mechanical vibrator, in addition to being coated with an antistatic hydrophilic coating. The function of the wind shield is to obstruct the wind coming from the South direction. The antistatic coating prevents the dust particles from adhering to the panel’s surface. The role of the mechanical vibrator is to shake off the deposited dust particles on the panel’s surface. The experimental results show that applying the antistatic coating together with the wind shield with vibrating the panel in case of the winter experiment preserved the efficiency of the panel, such that the drop in efficiency did not exceed the maintenance limit of 10% during the experiment. While in the summer experiment, the maintenance limit has been exceeded in the fifth week. This is mainly due to the effect of wind direction and rainfalls, which were present in the winter, unlike the summer experiment where winds and rainfalls are rarely found. This clearly shows that the combination of the wind shield and the mechanical vibrator together with the coating is a promising dust mitigation technique for PV panels operating light posts especially in winter.