Dust Particle Size Research Articles

Analytical Solution and Energy Behavior to a Forced Shock Wave Problem Under Dusty Gas Regime

ABSTRACTIn the presented research work, we have solved a new kind of problem of forced shock waves in a compressible inviscid perfect gas having dirty (dust) particles of small size in a one‐dimensional unsteady adiabatic flow. The approach that we have used is referred to as the generalized geometry approach. Here, we investigated how the density of the zone, which is undisturbed, changes as a function of the position from the point of the source of explosion. In addition, we have obtained analytically a novel solution to the problem in the form of a new rule of power of time and distance. Further, we have investigated the energy behavior of forced shock waves and interaction within the environment containing dust particles. Also, the behavior of the entire energy of a forced shock wave is expounded at different Mach numbers, respectively, for planar geometry, cylindrically symmetric geometry, and spherically symmetric geometry under a dusty gas medium. Furthermore, the findings show that dust particles in a gas produce a more sophisticated representation rather than the standard gas dynamics.

Study on improving self-cleaning performance of hydrophobic coating surface through freeze-thaw cycles

ABSTRACT This study employed a freeze-thaw cycle visualization platform alongside CCD imaging technology to conduct microscopic investigations into the freeze-thaw process under typical conditions. The observations identified three distinct stages in the freeze-thaw cycle: freezing, melting and disintegration, and melting and movement. Additionally, the experiment analyzed the particle size and composition of adhesive dust, as well as the effects of freezing temperature, freezing time, and thawing temperature on the contact angle between a hydrophobic surface and dust particles. Under a combination of influencing factors (freezing temperature of −8°C, freezing time of 60 minutes, melting temperature of 40°C, particle size of 800 mesh, and an impurity ratio of 1:1:1), the self-cleaning performance of the hydrophobic surface was significantly enhanced – the contact angle increased by 39.67% compared to standard surfaces. The maximum dust removal efficiency achieved was 37.52% in a single freeze-thaw cycle on hydrophobic surfaces. These findings present a novel approach to improving hydrophobic surface self-cleaning technology, with promising practical applications.

Synergy of chelating agents and surfactants on the wettability and pore structure of coal dust: Experimental study and molecular simulation

To reduce the hazards of coal dust pollution to miner health and the environment, and to realize efficient wetting and settling of coal dust, this paper evaluates the wettability of tetrasodium glutamate diacetate (GLDA)–aliphatic alcohol polyoxyethylene ether sodium sulfate (AES), hereafter termed G–A, by selecting the surfactant through macroscopic experiments and microscopic simulations. With the help of molecular simulation to study the synergistic mechanism of the surfactants and chelating agents, the functional group changes and mesoscopic modification of coal dust particles were evaluated in combination with characterization experiments. Comprehensive analysis showed that the G-A solution had the best wettability with a low surface tension of 22.77 mN/m, the diffusion rate of the solution increased to 1.25°/s, and the contact angle with the coal dust decreased to 18° within 12 s. After infiltration, the median particle size of coal dust reached 38.140 μm, which increased by 148 %. The pores and slits on the surface of the coal dust particles are further increased, providing surfactants with more extensive adsorption sites, and the proportion of hydrophilic groups on the surface of coal increased by 8.42 %, with the consequent improvement of wettability. This study provides a theoretical basis for the research and development of more environmentally friendly and efficient dust reducing agents in the field of spray dust reduction.

Self-cleaning of photovoltaic modules: The role of liquid droplets on hydrophobic surfaces in surface dust removal

Dust accumulation on photovoltaic (PV) panels reduces their energy efficiency. Although droplets play a crucial role in the self-cleaning of dust on the surface of PV panels, the underlying mechanism of surface dust self-cleaning in the presence of droplets has not been fully understood. This study aims to investigate the dust removal mechanisms on the surface of blank and coated PV panels and analyze the effects of factors such as dust particle size, PV panel tilt angle, and ash density on droplet self-cleaning efficiency. Our experiments show that superhydrophobic coatings can significantly improve the droplet self-cleaning efficiency and output power of PV panels. The maximum relative power recovery rate of the coated sample is 78.53%, which is much higher than 27.83% of the blank sample. To better understand the droplet self-cleaning mechanism, we analyze the differences in droplet self-cleaning between blank and coated PV panels from a mechanical perspective. Our model explains the main forces and motion modes of dust particles in the presence of droplets, and we find that smaller dust particles are easier to remove than larger particles. Additionally, we find that a smaller inclination angle of the PV panel surface inhibits the dust particle removal process. Finally, we conduct a comparative study between droplet self-cleaning and other self-cleaning methods to evaluate their effectiveness. Our results show that droplet self-cleaning is a more efficient and effective method for removing dust from PV panels.

Investigation of the Minimum Ignition Energy Required for Combustion of Coal Dust Blended with Fugitive Methane

Ventilation Air Methane (VAM) significantly contributes to global warming. Capturing and mitigating these emissions can help combat climate change. One effective method is the thermal decomposition of methane, but it requires careful control to prevent explosions from the high temperatures involved. This research investigates the influence of methane concentration and coal dust particle properties on the minimum ignition energy (MIE) required for fugitive methane thermal decomposition and flame propagation properties. This knowledge is crucial for the mining industry to effectively prevent and mitigate accidental fires and explosions in VAM abatement plants. Coal dust samples from three different sources were selected for this study. Experiments were conducted using a modified Hartmann glass tube and a Thermal Gravimetric Analyser (TGA). The chemical properties of coal dust were determined through ultimate and proximate analysis. The particle size distribution was determined using a Mastersizer 3000 apparatus (manufactured by Malvern Panalytical, Malvern, UK). The results showed that the MIE is significantly affected by coal dust particle size, with smaller particles (<74 µm) requiring less energy to ignite compared to coarser particles. Additionally, blending methane with coal dust further reduces the MIE. Introducing methane concentrations of 1% and 2.5% into the combustion space reduced the MIE by 25% and 74%, respectively, for the <74 µm coal dust size fraction. It was observed that coal dust concentration can either raise or lower the MIE. Larger coal dust concentrations, acting as a heat sink, reduce the likelihood of ignition and increase the MIE. This effect was noted at a methane concentration of 2.5% and coal dust levels above 3000 g/m3. In contrast, small amounts of coal dust had little impact on MIE variation. Moreover, the presence of methane during combustion increased the upward flame travel distance and propagation velocity. The flame’s vertical travel distance increased from 124 mm to 300 mm for a coal dust concentration of 300 g·m−3 blended with 1% and 2.5% methane, respectively.

Enhanced mass scattering efficiencies of background dust aerosols over East Asia following the passage of dust plumes

The transported dust particles significantly impact global weather and climate. Previous studies focused primarily on the physical and chemical properties of dust plumes, but the interaction mechanism between these dust plumes and background dust aerosols remains unclear. We explored this issue using in-situ observation data of the East Asia dust from the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) during January 2013. We identified a dust plume originating from the Gurbantunggut Desert, which triggered a four-day dust event with an average dust concentration of 67.2 μg m−3. Notably, this dust event led to a significant increase in mass scattering efficiencies of dust, shifting from an inverted U-shape to a continuously increasing pattern with wavelength. The enhanced dust mass scattering efficiency inhibited the development of the planetary boundary layer. These changes persisted for at least two weeks after the event, primarily due to the resuspension of deposited dust particles altering the size of background dust particle. Our findings highlight the ability of dust plumes to enhance the scattering efficiency of background dust aerosols and providing new insights into the complex interactions between dust and the atmosphere.

Experimental study of influence of coal dust physical–chemical properties on indirect dust suppression effect

Indirect dust suppression parameters are one of the main indicators for evaluating the performance of dust reduction, and the physical and chemical properties of coal dust are important factors affecting the indirect dust reduction effectiveness. To clarify the influence of coal dust physical and chemical properties on the indirect dust suppression effect, atomic force microscope(AFM), laser particle sizer, infrared spectrometer were used to analyse raw coal dust characteristics (the particle size, roughness, adhesion force and functional groups) sampled from different mines, and sedimentation and agglomeration experiments were used to study the indirect dust suppression effect (the law of wettability and agglomeration) of the coal dust under different characteristics. The results showed that the median particle size of SY and DJH coal dusts was significantly lower than that of HL and YH coal dusts. The average roughness ranged from 1.10 to 2.62 nm, and the maximum roughness ranged from 7.18 to 26.7 nm. The coal dust had a small adherence force, and the agglomeration ability occurred by itself was difficult. Furthermore, the difference of the functional groups structure for four coal dusts was small, but it showed an obvious difference in the proportion of functional groups. As the decrease of particle size, the roughness of coal dusts increased, and its wetting velocity decreasing trend showed a power function. The higher the surface roughness of coal dust, the stronger the hydrophobicity of coal dust. With the hydroxyl proportion percentage increased, the coal dust wetting velocity increased linearly, and the increase of hydroxyl functional group proportion greatly promoted the agglomeration of fine particle coal dust. The agglomeration effect enhanced first and weakened after with coal dust particle size decreased, which reflected the fact that the large-size coal dust was more easily wetted by reagents, but it was difficult to form stable liquid bridges. Furthermore, the smaller size of coal dust showed a poorly wettability, it was unable to form effective agglomerates. Coal dust adhered to the surface of the droplets under the action of the liquid bridging force, and as the water evaporated, the coal dust formed stable solid bridges between them.

Effect of Cutting Conditions on the Size of Dust Particles Generated during Milling of Carbon Fibre-Reinforced Composite Materials.

Conventional dry machining (without process media) of carbon fibre composite materials (CFRP) produces tiny chips/dust particles that float in the air and cause health hazards to the machining operator. The present study investigates the effect of cutting conditions (cutting speed, feed per tooth and depth of cut) during CFRP milling on the size, shape and amount of harmful dust particles. For the present study, one type of cutting tool (CVD diamond-coated carbide) was used directly for machining CFRP. The analysis of harmful dust particles was carried out on a Tescan Mira 3 (Tescan, Brno, Czech Republic) scanning electron microscope and a Keyence VK-X 1000 (Keyence, Itasca, IL, USA) confocal microscope. The results show that with the combination of higher feed per tooth (mm) and lower cutting speed, for specific CFRP materials, the size and shape of harmful dust particles is reduced. Particles ranging in size from 2.2 to 99 μm were deposited on the filters. Smaller particles were retained on the tool body (1.7 to 40 μm). Similar particle sizes were deposited on the machine and in the work area.

Sources and health risks of heavy metals in kindergarten dust: The role of particle size

Particle size effects significantly impact the concentration and toxicity of heavy metals (HMs) in dust. Nevertheless, the differences in concentrations, sources, and risks of HMs in dust with different particle sizes are unclear. Therefore, guided by the definition of atmospheric particulate matter, dust samples with particle sizes under 1000 μm (DT1000), 100 μm (DT100), and 63 μm (DT63) from Beijing kindergartens were collected. The concentrations of HMs (e.g., Cd, Pb, Zn, Ni, Cr, Ba, Cu, V, Mn, Co, and Ti) in dust samples with different particle sizes were measured. Besides, the differences in HM concentrations, contamination levels, sources, and source-oriented health risks in dust samples of different particle sizes were systematically explored. The results show that the concentrations of Mn, V, Zn, and Cd gradually increase with decreasing dust particle sizes, the concentrations of Ba and Pb show a decreasing trend, and the concentrations of Cr, Cu, Ni, and Co display an increasing and then decreasing trend. The degree of contamination of HMs in dust of different particle sizes varies, with Cd being the most dominant contaminant. Compared with DT1000 and DT63, DT100 is the most polluted. In addition, the sources of HMs in DT1000, DT100, and DT63 become more single with decreasing particle size, which may be mainly due to the particle-size effect inducing the redistribution of HMs in different sources. Notably, the potential health risk is higher in DT100 than in DT1000 and DT63. The highest contribution of industrial sources to the health risk is found in DT100, which is mainly caused by highly toxic chromium (Cr). This work emphasizes the importance of considering particle size in risk assessment and pollution control, which can provide a theoretical basis for precise management of HMs pollution in dust.

Sufficiency of near-surface water ice as a driver of dust activity on comets

Context. Nearly all contemporary theoretical research on cometary dust activity relies on models depicting heat transfer and sublimation products within the near-surface porous layer. Gas flow exerts a pressure drag to the crust agglomerates, counteracting weak gravity and the tensile strength of that layer. Our interpretation of data from the Rosetta mission, and our broader comprehension of cometary activity, hinges significantly on the study of this process. Aims. We investigate the role played by the structure of the near-surface porous layer and its associated resistance to gas flow, tensile strength, pressure distribution, and other characteristics in the scenario of the potential release of dust agglomerates and the resulting dust activity. Methods. We employ a thermophysical model that factors in the microstructure of this layer and radiative heat conductivity. We consider gas flow in both the Knudsen and transition regimes. To accomplish this, we use methods such as test-particles Monte Carlo, direct-simulation Monte Carlo, and transmission probability. Our study encompasses a broad spectrum of dust-particle sizes. Results. We evaluated the permeability of a dust layer composed of porous aggregates in the submillimetre and millimetre ranges. We carried out comparisons among various models that describe gas diffusion in a porous dust layer. For both the transition and Knudsen regimes, we obtained pressure profiles within a non-isothermal layer. We discuss how the gaps in our understanding of the structure and composition could impact tensile strength estimates. We demonstrate that for particles in the millimetre range, the lifting force of the sublimation products of water ice is adequate to remove the layer. This scenario remains feasible even for particles on the scale of hundreds of microns. This finding is crucial as the sublimation of water ice continues to be the most probable mechanism for dust removal. Conclusions. This study partially overturns the previously held, pessimistic view regarding the possibility of dust removal via water sublimation. We demonstrate that a more precise consideration of various physical processes allows elevation of the matter of dust activity to a practical plane, necessitating a fresh quantitative analysis.

Experimental investigation on the impact of water immersion time and particle size on the ignition characteristics of coal dust

After drying, water-immersed coal is more prone to spontaneous combustion than raw coal. However, the influence mechanisms of particle size and water immersion duration on the physicochemical properties of coal dust, as well as the explosion and fire hazards of water-immersed coal dust, have not been sufficiently investigated. In this study, two particle sizes of coal dust were selected, and experiments were conducted using the Godbert-Greenwald furnace, Hartmann tube, Muffle furnace, and Fourier Transform Infrared Spectrometer. The study investigated the impact of different water immersion times, dust particle sizes, and dust concentrations on the sensitivity of coal dust fires and explosions, analyzed the process of functional group changes in coal dust particles in water and other mechanisms of transformation. The results indicated that the water immersion process increased the number of active functional groups on the surface of coal dust, significantly reducing the Minimum Ignition Temperature (MIT) and Minimum Ignition Energy (MIE) values for different samples, and also enhancing the ignition sensitivity and peak temperature of coal dust layer fires. This study contributes to a deeper understanding of the characteristics of coal dust and is of great significance for improving the prevention and control of coal dust fires and explosions.

Characterising polycyclic aromatic hydrocarbons in road dusts and stormwater in urban environments.

The presence of polycyclic aromatic hydrocarbons (PAHs) pollution on urban road surfaces is one of the major environmental concerns. However, knowledge on the distribution variability of PAHs in road dusts (RDS) and stormwater is limited, which would restrict the further risk evaluation and mitigation implementation of PAHs in road stormwater runoff. This study collected RDS samples and stormwater samples on fourteen urban roads in Shenzhen, China. This study investigated the variation of sixteen PAHs species in RDS and stormwater, and further evaluated the intrinsic and extrinsic factors which influence PAHs accumulation on urban road surfaces. The research outcomes showed significant differences on spatial distribution of PAHs in RDS and in stormwater. The land use types, industrial, commercial and port areas and vehicular volume have a positive relationship with PAHs abundance while dust particle size showed a negative correlation with PAHs abundance. For two phases in stormwater, fluctuation of PAHs with the rainfall duration in total dissolved solid (TDS) was more intensive than in dissolved liquid phase (DLP). This indicated when PAHs attached to RDS enter stormwater, most of PAHs still tend to be on solid particles than in liquid. The study outcomes are expected to contribute to efficient designs of PAHs polluted stormwater mitigation.

Numerical simulation of dust deposition characteristics of photovoltaic arrays taking into account the effect of the row spacing of photovoltaic modules

Dust deposition on the surfaces of Photovoltaic (PV) arrays during their operation markedly affects their power generation efficiency. Previous research has overlooked the impact of the row spacing of PV modules on the actual dust deposition on PV arrays. This study investigates the dust deposition process and its behavior on PV arrays considering variations in row spacings, inlet wind speeds, dust particle sizes, and dust particle counts. By employing commercial Computational Fluid Dynamics (CFD) software, incorporating the SST k-ω turbulence model and discrete particle model, numerical simulations were performed to analyze the airflow field, dust particle trajectories, dust deposition patterns, and deposition rates on the PV array through grid-independent verification and numerical validation. At the same time, we performed a comparative analysis of the deposition rate considering the rebound of dust particles on the PV module surface versus the case where rebound is not considered. Results revealed that the maximum dust deposition rates at different inlet wind speeds were 6.84 %, 8.84 %, 11.0 %, and 14.6 %, corresponding to dust sizes of 50 μm, 100 μm, 120 μm, and 300 μm, respectively. Smaller dust particles exhibited lower deposition rates, while larger particles were influenced more by mass inertia and gravity, leading to predominant deposition on the front row of PV modules. Larger dust particles are more likely to deposit primarily on the front row of PV modules in a PV array. The tilt angles of 30°, 45°, and 60° were chosen to study the effects of different tilt angles on the dust deposition of PV arrays, and the results show that the dust deposition rate decreases as the tilt angle increases, and it is worth noting that the larger the tilt angle, the larger the dust deposition rate is when the dust particles are especially small as 5 μm. When wind speeds are low and dust particles are small, the dust deposition rate gradually rises as the row spacing increases. However, at higher wind speeds with small dust particles, the row spacing has minimal impact on the dust deposition rate. Conversely, with larger dust particles, increasing the row spacing results in a lower dust deposition rate. These findings underscore the significance of optimizing PV array design for enhanced power generation efficiency.

Research on particle size distribution and composition of road deposit dust in Xi'an: From the perspective of non-exhaust emissions

Road dust, containing tire-road wear particles, atmospheric dust, or construction-related particles, contaminates road environments and poses a health hazard when inhaled by humans. To further explore the particle size and composition of road deposit dust, this study collects these particles in Xi'an, considering various road grades, materials, service conditions, sections, and locations. The collected particles undergo electron microscopy, laser particle size, thermal, mass spectrometry, infrared spectroscopy, and inductively coupled plasma analyses. Qualitative and quantitative analysis of the particles has been conducted, leading to the following conclusions: Asphalt & tire contribute 8.5% of the road deposit dust, while wear from calcium carbonate accounts for approximately 30%. The average particle size on urban roads (392 μm) is 1.25 times that of rural roads (312 μm). The smaller particles on rural roads are more easily resuspended and inhaled, posing health risks and requiring more attention. Brake zones, which often have 1.4 times the metal content compared to mid-sections, including potentially carcinogenic chromium (Cr), should receive focused watering and adsorption due to brake zone where is also at intersections and pedestrian crossing. New roads, which generate 3-6 times more organic matter than old roads, requires continuous cleaning after opening to traffic. Surface-blocked asphalt concrete (AC) pavements, as their lack of pores can lead to easy re-suspension of deposited particles due to tire-road interaction should also be attention. This study aims to contribute to the field of traffic-related dust pollution cleaning strategies and non-exhaust emissions mitigation measures in the future.

Enhancing submicron dust capture in high-temperature flue gases: A computational study on gradient pore-buried tube granular bed filters

Granular bed filters (GBF) represent a highly effective technology for purifying high-temperature dusty flue gases, although their efficiency in capturing submicron particles remains limited. A novel gradient porosity GBF model with varying bed structures and heat exchange capabilities was proposed. In this research, we employed CFD software to elucidate the movement and heat transfer process of 1 μm dust particles within gradient porosity GBFs and heat exchanger tubes. By optimizing the model under the conditions of a 0.5 m/s inlet flue gas flow rate and 1 μm dust particle size, we achieved a 345.62% increase in filtration efficiency and a 76.61% reduction in pressure drop. The findings indicate that the proposed GBF outperforms other models across various flue gas flow rates in terms of filtration efficiency. The impact of the flue gas flow rate on the combined filtration efficiency for submicron dust on the proposed GBF model was notably significant.

Impact of Respiratory Dust on Health: A Comparison Based on the Toxicity of PM2.5, Silica, and Nanosilica.

Respiratory dust of different particle sizes in the environment causes diverse health effects when entering the human body and makes acute or chronic damage through multiple systems and organs. However, the precise toxic effects and potential mechanisms induced by dust of different particle sizes have not been systematically summarized. In this study, we described the sources and characteristics of three different particle sizes of dust: PM2.5 (<2.5 μm), silica (<5 μm), and nanosilica (<100 nm). Based on their respective characteristics, we further explored the main toxicity induced by silica, PM2.5, and nanosilica in vivo and in vitro. Furthermore, we evaluated the health implications of respiratory dust on the human body, and especially proposed potential synergistic effects, considering current studies. In summary, this review summarized the health hazards and toxic mechanisms associated with respiratory dust of different particle sizes. It could provide new insights for investigating the synergistic effects of co-exposure to respiratory dust of different particle sizes in mixed environments.

Experimental Study on Flame Spread of Pine Wood Dust Layer Under Horizontal Rotation Condition

ABSTRACT The rotating discs of wood polishing machines and the rotating bases of winding machines rotate horizontally during operation, and a layer of wood dust may be deposited on their surfaces. The study of flame spreading of wood dust layer in the rotating state has not been reported in the literature. Based on this situation, in this study, the flame spreading of pine wood dust layers in three particle size ranges under stationary and different rotating conditions were carried out and analyzed comparatively. The results show that the flame spreading speed of the pine wood dust layer from 74~100 micrometers positively correlates with the rotational angular velocity. The flame-spreading speed of a pine wood dust layer larger than 100 micrometers negatively correlated with the rotational angular velocity. This indicates that the flame spreading speed of the pine wood dust layer is affected by the combined effect of dust particle size and dust layer motion state. The flame propagation speed of the 74~100 micron pine dust layer was 3.3 mm/s when the rotational angular velocity was 0.167 rad/s, which was the maximum flame propagation speed in all experimental conditions. The maximum flame height of the pine dust layer in the rotating state was at least 55.6% higher than that in the stationary state.From the combined view of the three parameters of flame spreading speed, flame duration, and maximum flame height, the fire danger is greater in the rotating state than in the stationary state. Within a certain range, the larger the rotational angular velocity, the greater the fire hazard.

Dynamic wetting characteristics of two droplets impacting a spherical dust particle

The removal of dust based on water misting is one of the most effective measures for dust control, and the basis of this method lies in the liquid–solid impact behavior. To further improve the dust removal efficiency, in this work, the removal mechanism was studied at the microscopic level, and the dynamic impact between two water droplets and a spherical dust particle was simulated using the coupled level-set/volume-of-fluid (CLSVOF) method. The optimal parameter ranges for micron-level dust removal were determined through the method of variable control, and the reliability of the obtained results was experimentally verified. When two droplets continuously or simultaneously impact a spherical particle, the liquid film formed undergoes deformation phenomena such as fusion, rupture, stretching, contraction, and fragmentation. The liquid film is more likely to break at higher droplet velocities, leading to the filling of the gas film and hindering the wetting process. The optimum contact angle and velocity range of the liquid droplets to completely encapsulate the dust particles were found to be θ = 2 and V = 10–20 m/s, respectively. The experimental results also showed that for the same dust particle size, the dust removal efficiency initially increased but then decreased with increasing dust concentration. The optimum dust removal efficiency of 98.1 % was achieved for θ = 2 and V = 10 m/s. This study sheds new light on the dust removal mechanism of water mist-based dust removal technologies and can aid in the design and parameter optimization of more effective dust suppression systems.

Research of dust removal performance and power output characteristics on photovoltaic panels by longitudinal high-speed airflow

Photovoltaic (PV) panels' photoelectric conversion efficiency will decrease as dust deposition on their surface. An approach to dust removal on the PV panel's surface by longitudinal high-speed airflow was investigated to increase the output power. In this paper, commercial CFD software was used to numerically simulate the characteristics of dust removal by longitudinal high-speed airflow. The PV panels' output characteristic model under the action of dust removal by high-speed airflow is established by Simulink software, and the influence of high-speed airflow on the output characteristic is studied. Firstly, the dust removal mechanism of the PV panel under high-speed airflow is studied. Secondly, the impact of different tilt angles of the PV panel, dust particle size, airflow velocity, and blowing time on the dust removal effect of the PV panel surface were studied. The optimal airflow velocity and blowing time were obtained according to the airflow velocity and blowing time and their influence on the dust removal rate. Finally, the effect of high-speed airflow dust removal on PV power generation's efficiency and output characteristics is studied. The findings demonstrate that as the tilt angle increases, so does the dust removal rate increases continuously. In addition, the rate at which dust is removed increases with airflow velocity and blowing time. When the tilt angle is 30°, the best airflow velocity of dust removal is 5 m/s, and the best blowing time is 8 s. When the tilt angle is 45°, the best airflow velocity of dust removal is 10 m/s, and the best blowing time is 5 s. With the increase in airflow velocity and blowing time, the output power of PV panels continues to increase. When the airflow velocity is 10 m/s, and the blowing time is 5 s, 7.5 s, 12.5 s, and 15 s, the maximum output power after dust removal is increased by 15.44 %, 23.05 %, 23.38 %, and 23.39 %. This paper's research results can guide the design of the practical engineering application of longitudinal blowing high-speed airflow in the dust removal of PV panels.

Variation Law of Hybrid Explosion Characteristic Parameters of Gas and Coal Dust Coupled with Multiple Factors.

This study aims at extensively investigating the explosion characteristics of a hybrid mixture of gas and coal dust. Accordingly, the standard 20 L spherical explosion system was applied to measure parameters such as the lower explosion limit, maximum explosion pressure, and index of the hybrid mixture of different concentrations of gas and coal dust. Moreover, different coal dust particle sizes and components were measured. With regard to coal dust with different particle sizes and components, the obtained results revealed that, while the addition of gas significantly reduced the lower explosion limit, the maximum explosion pressure and index were increased; that is to say, the presence of gas will increase the explosion risk of coal dust. However, under conditions in which the particle size of the coal dust was large or the volatile content was low, the addition of gas was found to lead to a higher decrease of the lower explosion limit; this is, while the maximum explosion pressure and explosion index were increased. Consequently, gas can be argued to have a greater influence on the explosion risk of coal dust with a large particle size or low volatile content. Furthermore, regardless of the particle size or the volatile content of coal dust, the maximum explosion pressure and explosion index of the hybrid mixture were observed to be higher than that of the pure coal dust but lower than that of the pure gas. That is to say, the explosion intensity of the gas/coal dust composite system is higher than that of pure coal dust but less than that of pure gas. The research results can provide theoretical basis for coal mine explosion disaster prevention and control and have important significance.