Distribution Characteristics Of Particles Research Articles

Theoretical generation and manipulation of concentric rings by light waves on scattering from a collection of anisotropic particles

A theoretical method is proposed for generating far-zone scattered fields with concentric ring-like intensity distribution by properly controlling the distribution characteristics of particles. As an example, a collection of anisotropic Gaussian-centered determinate particles with quasi-homogeneous distribution is discussed. The results show that the number and size of concentric rings can be flexibly adjusted by controlling the structural parameters of the collection of particles. In addition, by adjusting the effective length of each particle’s scattering potential in different directions, a conversion of the distribution of the scattered field from the concentric ring to the crescent lobe can be achieved.

Whole Process Analysis and Fate Behavior of Microplastics in Urban Wastewater Treatment Plants, Including their Occurrence Forms, Components, and Removal Efficiency

Microplastics are among the most difficult new pollutants to remove in wastewater treatment plants. In order to explore the occurrence form, size distribution, composition, removal efficiency, migration law, and fate behavior characteristics of microplastic particles in sewage plants, taking a sewage treatment plant in Hohhot as an example, a total of 17 sampling sites were set up. The LAS X software counted the shape, abundance, and size of microplastics and conducted a full-process analysis. The results showed that： fibrous microplastics had the highest abundance and widest distribution and were the main form of existence, accounting for 61.8% of the total abundance； the size of microplastics ranged mainly between 0 and 1.00 mm, and among the four sizes, the abundance of microplastics 0.25 to 0.50 mm in China was the highest, accounting for 32.9%. Among the eight types of plastic components detected, polyester substances （PET, PBT）, cellulose, and polypropylene （PP） were the main components, accounting for 25%, 21%, and 17%, respectively. The influent abundance of the sewage plant was （73 ±5） n·L-1, the effluent abundance was （14 ±2） n·L-1, and the overall removal rate was （80.8 ±12.1）%. Among the three treatment stages of the sewage plant, only the primary treatment played a role in removal, and the abundance of microplastics surged in the secondary treatment. Different structures playing a major role in the removal of microplastics were fine grids （49.2 ±7.4）% and secondary sedimentation tanks （92.4 ±13.9）%. Microplastics mainly existed in the form of fibers, fragments, and films. The proportion of fibers was approximately 70%, and the size of fragments was mainly concentrated between 0.50 and 5.00 mm. Most fragments were in the range of 5.00 mm, accounting for 50%, making them the main form apart from fibrous. The film-like size was mostly concentrated in the range of less than 0.50 mm, accounting for more than 10%. Therefore, improving the removal of small-sized fibrous and film-like microplastics and large-sized fragmented microplastic particles can effectively reduce the pollution risk of microplastics in the environment caused by sewage plant drainage.

Removal of micro-nano particles based on water-assisted enhanced plasma shock wave

Foreign micro/nanoparticles can compromise the production and performance of semiconductors, high-energy laser systems, and other technologies. Owing to the strong adhesion (in GPa) of these particles to the surfaces of these devices, removing them using traditional methods such as ultrasound is difficult. Laser plasmas at high temperatures and pressures can effectively clean the micro/nanoparticles. Compared with traditional air media, laser plasma generates stronger shock waves and water flow erosion underwater, which can effectively clean these particles. In this study, we analysed the particle removal process under the action of laser plasma in water dielectrics, primarily the distribution characteristics of particles under spatial phase transition, final removal efficiency, removal thresholds, and optimal removal regions of particles with different sizes, as well as the corresponding academic analysis based on thermodynamic effects. We used a silicon wafer that was subjected to a high-energy laser beam to generate plasma shock waves underwater, which were used to remove micro- and nano-sized impurities. We found that the shock wave pressure of the plasma and water flow gradually decreased from the centre to the outside, and the corresponding action region could be divided into three areas, namely, 0–30°, 30–45°, and 45–50°, with particle removal rates of 96.93 %, 75.52 %, and 36.60 %, respectively. For particles in the 0–30° and 30–45° regions, the maximum removal rate corresponded to particle sizes ranging from 50–200 nm and greater than 200 nm, respectively. However, in the 45–60° region, the pressure of the shock wave was lower than the fragmentation threshold and, hence, had the worst particle removal effect owing to the lowest pressure. We believe that these findings will provide guidance for the subsequent development of particle removal technologies using underwater laser plasma shock waves.

Study on Sensitivity Mechanism of Low-Permeability Sandstone Reservoir in Huilu Area of Pearl River Mouth Basin

Reservoir sensitivity is a parameter that is used to evaluate the degree of change in reservoir permeability under the influence of external fluids. Accurate evaluation of reservoir sensitivity is conducive to the optimization of fluid parameters during exploration and development. Taking the Wenchang Formation and Enping Formation of the Paleogene in the Huilu area of the Pearl River Mouth Basin as the research object, reservoir sensitivity experiments were carried out. Combined with the corresponding experimental results obtained using methods such as thin section identification, scanning electron microscopy (SEM), X-ray diffraction (XRD), mercury intrusion porosimetry (MIP), and screening analysis, based on mineral sensitization and pore structure sensitization, qualitative and quantitative evaluations of reservoir sensitivity were carried out, and factors affecting sensitivity and sensitization mechanisms were analyzed. This work shows the following: (1) The sandstone reservoirs in the two areas have the same clay type, but the total clay content of the Wenchang Formation is greater than that of the Enping Formation. The porosity of the Wenchang Formation is less developed than the Enping Formation. (2) The Wenchang Formation has weak or moderately weak water sensitivity and moderately weak or moderately strong flow velocity sensitivity. The water sensitivity of the Enping Group samples is moderately weak or moderately strong, the flow rate sensitivity is moderately weak, the alkali sensitivity is weak, the acid sensitivity is moderately weak, and the salinity sensitivity is moderately weak or moderately strong. (3) The sensitivity of the Wenchang Formation is mainly affected by the content of clay minerals. The sensitivity of the Enping Formation is also affected by the clay content and type. Although the clay content is not high, the permeability is more susceptible to sensitivity due to the pore structure and debris particle distribution characteristics. These conclusions are beneficial for the selection of fluid parameters and efficient reservoir development.

Distribution and movement of fine particles injected in a gas–solid fluidized bed with hydrocarbon liquid spray

In a gas–solid fluidized bed with hydrocarbon liquid spray, a liquid-affected zone (cloudy zone) and a gas–solid zone (non-cloudy zone) coexist. Fine particles with different diameters are injected and shuttle between the two zones to simulate the motion of growing catalyst particles in an industrial fluidized bed reactor. The movement and distribution patterns of the fine particles are investigated via high-speed image and infrared image approaches developed. The probability density based on the coordinates of fine particles reflects clearly the distribution characteristics of fine particles in the bed at different times. Fine particles with smaller diameters are more easily enriched locally during the injection and diffusion process. Moreover, the proportion of fine particles in the cloudy zone to the total fine particles increases with the diameter of fine particles.

Characteristics of Soil Particle Sizes and Fractal Parameters under Different Plantation Types of Populus alba

Vegetation plays a leading role in restoring desert ecosystems and increasing productivity. In this study, we elucidate the improvement effects of different restoration areas of Populus alba on the soil particle distribution, sedimentation environment, and fractal characteristics. We selected the restoration areas of P. alba × Caragana korshinskii (YN), P. alba × Hedysarum leave (YY), and P. alba × Hedysarum scoparium (YH), which have a history of twenty-one years. We analyzed the soil nutrients, soil particle size, soil particle size parameters, soil fractal dimension (D) values, and soil multifractal parameters at soil depths of 0–80 cm. We found that the YN, YY, and YH significantly increased the soil nutrients and soil fine particles (p < 0.05) and changed the deposition pattern of the soil particles in the sandy area. The YN, YY, and YH promote soil particle refinement and reduce the sorting performance of the soil particles. The vegetation promotes extremely positive-skewed and very leptokurtic soil particle distributions. The D values in the YN, YY, and YH restoration areas increased by 7.62%–27.94%, 7.36%–26.28%, and 7.10%–17.92%, respectively, relative to those of the LS. The construction of the different restoration areas of P. alba has made the distribution of the soil particles nonuniform. Compared with the YY and YH plantations, the distribution range of the soil particles in the YN plantation is wider, and the distribution heterogeneity is greater. In addition, we found that the fractal parameters are influenced by the soil physicochemical properties, the depositional environment, and vegetation factors. Therefore, we believe that D values and multifractal parameters are necessary as additional information for desert soil texture improvement. The results of this study provide a scientific and theoretical basis for the future revegetation of deserts.

Determining the optimal gradation of mixed recycled aggregate containing coal gangue brick aggregate

Aggregate grading design is the foundation of concrete mix proportion design. Existing aggregate grading design methods are based on the tightest accumulation theory of homogeneous natural aggregates. However, this method has not been applied to mixed recycled aggregate (MRA) containing coal gangue brick aggregate (CGBA) (hereinafter referred to as MRA) due to significant differences in physical and mechanical properties. In this study, we subjected five types of MRA (initial particle size: 19–26.5 mm) to confined crushing, sieving, and grading composition analysis, then configured recycled concrete. We investigated the determination method of the optimal gradation of MRA, summarized the composition, particle distribution characteristics, and fractal characterization of the optimal gradation. This study focused on analyzing the factors that affect the compressive strength of recycled concrete, as well as examining the mix proportion design method. The results reveal that the optimal gradation of MRA can be determined using the five-stage loading method for approach minimum porosity. Our analysis of MRA gradation suggests that the mix proportion design of recycled concrete should be determined by considering the porosity of optimal gradation and the surplus volume coefficient of slurry. Finally, we determined that the water-binder (W/B) ratio is the primary factor that affects the compressive strength, while the CGBA’s intrinsic strength has a minimal impact. The replacement ratio of CGBA primarily affects the porosity of MRA and the W/B ratio, indirectly reducing recycled concrete’s compressive strength. Based on our findings, we recommend that the replacement ratio of CGBA should not exceed 50%. This study can promote the recycling of recycled concrete containing CGBA.

Particle distribution and two-phase flow characteristics of twin-screw pump during solid-liquid transfer

The twin-screw pump is a kind of positive displacement machinery with smooth pressure and flow pulsation and strong self-priming ability, which is widely used in the fields of oilfield production, marine engineering, and other fields. However, in the process of conveying liquid-phase media, it is difficult to avoid the inclusion of solid impurities and grit, resulting in wear of the pump casing and rotor, and the pump’s pressurization capacity is reduced or even shut down. At present, the solid-liquid two-phase flow characteristics within the twin-screw pump have not been clarified, which hinders the study of particle wear in the pump. In this paper, a solid-liquid two-phase flow study is carried out on a twin-screw pump through numerical simulation and experimental testing. The distribution of particles with different diameters in the rotor domain with the liquid-phase transport process is explored by simulating the two-phase flow under different differential pressures and particle concentrations. The results show that the particles in the rotor domain are mainly distributed in the region away from the male and female rotor engagement, and the number of particles near the engagement is small but the velocity is higher under the influence of the clearance jets; the elevation of the differential pressure and the particle concentration increase the risk of the particles to collide with the rotor more frequently and at higher velocity; at different particle concentrations, new localized vortices are caused by particle conveying which compared to pure liquid transport, but there are also cases where the original vortices are suppressed. The results will provide a theoretical basis for further research on particle wear characteristics in twin-screw pumps.

Effect of Mineral Grain and Hydrate Layered Distribution Characteristics on the Mechanical Properties of Hydrate-Bearing Sediments

The mechanical characteristics of gas hydrate-bearing sediments (HBS) are important for evaluating reservoir stability. The interbedded formation of HBS is common in target mining reservoirs. Existing studies on the triaxial mechanical properties of HBS are primarily based on homogeneous and isotropic samples. Therefore, the stress–strain law of the target mining reservoirs cannot be predicted accurately. In this study, a series of sediment models with interlayers of coarse and fine mineral grains were established based on the PFC3D code, and the influence of the layered distribution characteristics of sediment particles and hydrates on the macroscopic mechanical behaviour of the reservoir was comprehensively analysed. The triaxial compression simulation results indicate that the peak strength, deformation modulus, and cohesion of the layered HBS are significantly lower than those of the homogeneous model. The deformation modulus of the reservoir is mainly affected by the fine-grained layer without hydrates. When the coarse and fine grains correspond to different mineral components, the two minerals are heterogeneous in terms of their micromechanical parameters, which can further reduce the macroscopic mechanical parameters of the HBS. In addition, the layered distribution of hydrate results in significant anisotropy of the reservoir. This study constitutes a reference regarding the control mechanism of gas hydrate reservoir strength.

Multi-scale analysis of damping characteristics of dry mixed rubberized porous asphalt mixtures for tire-pavement noise reduction

Waste rubber particles have the potential to enhance the damping performance of asphalt pavement. However, there is a scarcity of research on the mechanism of the influence of rubber particles on the damping characteristics of asphalt mixtures. The purpose of the paper is to explore the influence of rubber particles on the damping characteristics, and reveal the noise-damping mechanism of dry mixed rubberized porous asphalt mixture (RPAM). The dynamic modulus test based on UTM was used to characterize the dynamic stiffness characteristics and energy dissipation capacity of RPAM. The self-made free vibration-damping test was applied to evaluate the damping properties of RPAM. X-ray Computed Tomography (CT) was used to scan the specimens of RPAM, and image analysis techniques were established to study the distribution characteristics of rubber particles. The correlation between the distribution characteristics of rubber particles and damping properties was constructed to explore the damping mechanism of the RPAM. The results showed that with the increase of rubber particle content, the stiffness of RPAM decreases. From an energy perspective, RPAM with more rubber particles has a stronger energy dissipation ability, resulting in better damping properties. From a microscopic perspective, RPAM with more rubber particles has a larger proportion of effective rubber particles, which are key to improving damping properties. It is worth noting that the rubber particle content should not exceed 3% to meet the requirements of pavement performance. The findings offer practical guidelines for the design of low noise pavement.

Distribution and Fractal Characteristics of Outdoor Particles in High-Rise Buildings Based on Fractal Theory

It is of great significance to understand the particle distribution characteristics at different heights to effectively control particle pollution. Based on fractal theory, the fractal dimension of outdoor particles in a high-rise building in Xi’an and its relationship with the concentration of particles with different particle sizes are discussed and analyzed in this paper. The results indicate that the atmosphere in Xi’an is mainly composed of fine particles and that the average proportion of particles ranging from 0 to 1.0 µm is approximately 99.885% of the total particulates. The fractal dimension of particles in the atmosphere at different heights ranges from 5.014 to 5.764, with an average fractal dimension of 5.456. In summer, the fractal dimension of the outdoor particles on the 17th floor was the largest, at 5.764. The fractal dimension in summer is relatively high, being 0.158 higher than that in winter on average. The larger the fractal dimension, the higher the proportion of fine particles. In addition, the fractal dimension can characterize the adsorption of toxic and harmful gases by particles well. It provides parameter support for understanding particle distribution and the effective control of atmospheric particles at different heights and application values.

The spatial phase transition of micro/nano particles and its effect on the cleaning efficiency of laser-plasma shock wave cleaning

Plasma cleaning is an effective method for removing micro/nanoparticle particles, thus solving the pollution problem of micro/nanoparticle instruments. However, the lack of research on the phase transition evolution law of micro/nanoparticles under the action of plasma affects the popularization and application of this method and is the key factor that affects the cleaning quality. The focus of this study is to analyze this law. Through experimental observation and finite element simulation, the spatial phase transition distribution characteristics of particles and the influence law of laser parameters are analyzed. Moreover, the effect of the particle phase transition on the cleaning process is discussed. The removal threshold and the best removal area of different particles are presented, and a reference and guidance for the follow-up development of laser-plasma shock wave removal technology are provided.

Plastic and paint debris in marine protected areas of Peru

Contamination with anthropogenic debris, such as plastic and paint particles, has been widely investigated in the global marine environment. However, there is a lack of information regarding their presence in marine protected areas (MPAs). In the present study, the abundance, distribution, and chemical characteristics of microplastics (MPs; <5 mm), mesoplastics (MePs; 5–25 mm), and paint particles were investigated in multiple environmental compartments of two MPAs from Peru. The characteristics of MPs across surface water, bottom sediments, and fish guts were similar, primarily dominated by blue fibers. On the other hand, MePs and large MPs (1–5 mm) were similar across sandy beaches. Several particles were composite materials consisting of multiple layers confirmed as alkyd resins by Fourier-transformed infrared spectroscopy, which were typical indicators of marine coatings. The microstructure of paint particles showed differentiated topography across layers, as well as different elemental compositions. Some layers displayed amorphous structures with Ba-, Cr-, and Ti-based additives. However, the leaching and impact of potentially toxic additives in paint particles require further investigation. The accumulation of multiple types of plastic and paint debris in MPAs could pose a threat to conservation goals. The current study contributed to the knowledge regarding anthropogenic debris contamination in MPAs and further elucidated the physical and chemical properties of paint particles in marine environments. While paint particles may look similar to MPs and MePs, more attention should be given to these contaminants in places where intense maritime activity takes place.

Distribution Characteristics of Cooking Oil Fume Particles in Residential Kitchens in Cold Regions

A kitchen is an important part of a residence, and air quality in kitchens is a major factor affecting residents’ health and performance. Its influence is especially more evident in kitchens with typical Chinese cooking. Thus, it is important to understand distribution characteristics of oil fume particles in Chinese kitchens, and research on typical Chinese kitchen environments and movement characteristics of soot particles should be emphasized. Therefore, to understand the air pollution in kitchen environments, a full-scale experimental platform was built based on common Chinese-style residential kitchens to monitor the soot particles, explore the space–time distribution characteristics of the soot particles, and analyze the variation characteristics and distribution laws of number concentration (NC) and mass concentration (MC). The results indicated that NC0.3μm value fluctuated slightly during the whole cooking process, while NC0.3μm~0.5μm and NC0.5μm~1.0μm fluctuated sharply. During the peak period, NC0.3μm~0.5μm and NC0.5μm~1.0μm were significantly higher than those at the beginning and end of cooking (p &lt; 0.05), and there was no significant difference between values of NC0.3μm~0.5μm and NC0.5μm~1.0μm at the beginning and end of cooking (p &gt; 0.05 for both). NC0.3μm and NC0.3μm~0.5μm were significantly different between each position (p &lt; 0.05 for all). There were also significant differences in NC0.3μm between pure meat dishes, pure vegetable dishes, and mixed dishes (p &lt; 0.001). The proportion of cooking meat will significantly affect the composition and concentration of lampblack particles. Type of dishes is an important influencing factor for the emission rates of particulate pollutants. Small-sized lampblack particles were more likely to diffuse to the surroundings and affected the air quality of the whole room. Particulate matter in the kitchen space during the frying process is more harmful to the health of personnel.

Cometary dust collected by MIDAS on board Rosetta

Context. The Micro-Imaging Dust Analysis System (MIDAS) atomic force microscope (AFM) on board the Rosetta comet orbiter has been dedicated to the collection and 3D topographical investigation of cometary dust in the size range of a few hundreds of nanometers to tens of micrometers with a resolution down to a few nanometers. Aims. We aim to catalog all dust particles collected and analyzed by MIDAS, together with their main statistical properties such as size, height, basic shape descriptors, and collection time. Furthermore, we aim to present the scientific results that can be extracted from the catalog, such as the size distribution and statistical characteristics of cometary dust particles. Methods. Through a careful re-analysis of MIDAS AFM images, we make a significant update and improvement to the existing MIDAS particle catalog, resulting in the addition of more particles and newly developed shape descriptors. The final product is a comprehensive list of all possible cometary dust particles detected by MIDAS. The catalog documents all images of identified dust particles and includes a variety of derived information tabulated one record per particle. Furthermore, the best image of each particle was chosen for subsequent studies. Finally, we created dust coverage maps and clustering maps of the MIDAS collection targets and traced any possible fragmentation of collected particles with a detailed algorithm. Results. The revised MIDAS catalog includes 3523 MIDAS particles in total, where 1857 particles are expected to be usable for further analysis (418 scans of particles before perihelion + 1439 scans of particles after perihelion, both after the removal of duplicates), ranging from about 40 nm to about 8 μm in size. The mean value of the equivalent radius derived from the 2D projection of the particles is 0.91 ± 0.79 μm. A slightly improved equivalent radius based on the particle’s volume coincides in the range of uncertainties with a value of 0.56 ± 0.45 μm. We note that those sizes and all following MIDAS particle size distributions are expected to be influenced by the fragmentation of MIDAS particles upon impact on the collection targets. Furthermore, fitting the slope of the MIDAS particle size distribution with a power law of a · rb yields an index b of ~−1.67 to −1.88. Lastly, based on the created dust coverage maps and clustering maps of the MIDAS collection targets, we determined the particle fragmentation ratio of 4.09 for nominal activity and 11.8 for the outburst, which underlines that parent particles with faster impact velocity are more likely to be fragmented during dust collection.

Numerical study on particle distribution characteristics of slush hydrogen in a cryogenic tank

A numerical model considering phase change and heat transfer was established by the Euler-Euler two-fluid method to investigate the storage characteristics and two-phase flow field of slush hydrogen. Numerous numerical simulations were performed to discuss the effect of particle diameter (dp = 0.02–0.5 mm), content of solid hydrogen (αs = 10%–50%), and heat leakage (q = 50–200W·m−2) on the flow field. It was found that particle deposition could occur during the storage process, and there exist moving vortices with contrary directions under specific conditions. The sedimentation characteristics and vortex size are influenced by many factors including particle size, solid hydrogen content, and heat leakage. An increase in particle size could lead to the strengthening of precipitation and the expansion of the counterclockwise vortex region on the right side of the tank. And the increase in solid hydrogen content could result in more deposition and more collisions and friction between particles. Moreover, the increase in heat leakage could increase the area of the counterclockwise vortex. Numerical results of the deposition and flow field characteristics in the storage tank could clearly show the physical law of the slush hydrogen so that the uniform distribution of slush hydrogen could be promoted for efficient storage and application.

A Localized and Surprising Source of Energetic Ions in the Uranian Magnetosphere Between Miranda and Ariel

AbstractIn situ exploration of Uranus has been limited to a single flyby encounter by the Voyager 2 spacecraft in January 1986. Nonetheless, new investigation has led to significant questions about the origin of energetic ions observed in the region between its moons Miranda and Ariel. Radial and pitch angle diffusion modeling suggests that typical magnetospheric sources cannot explain the observed characteristics of these energetic ions. We suggest that these are likely being introduced by a source from one of these moons and give rise to waves that could result in the observed particle distribution characteristics. This may reveal that internal plasma sources in the system may be important for Uranus' magnetospheric dynamics and may contribute to its unexpectedly strong radiation belts.

Simulation analysis of gas–solid flow characteristics and water evaporation in flue gas semi‐dry desulphurization process based on CPFD method

AbstractThe gas–solids flow in an industrial‐scale semi‐dry method desulphurization tower is simulated by the computational particle fluid dynamics (CPFD) approach. Compared with previous studies on desulphurization towers, this study focuses on analyzing particle distribution characteristics such as particle volume fraction, temperature distribution, and residence time. The simulation fully considered the particle–fluid, particle–particle, and particle–wall interactions in the desulphurization tower. Based on these considerations, the effects of flue gas inlet velocity and temperature on the gas–solid distribution characteristics of the desulphurization tower are simulated. An optimization scheme for adjusting the gas–solid flow in the desulphurization tower is proposed. The research results show that the error between the CPFD simulation data and experimental data is small and the changing trend is consistent. The particles in the bed of the desulphurization tower show a typical core–annulus flow. The distribution of gas and particles in the bed has a serious deviation with the increase of the flue gas inlet velocity and temperature. As the axial height of the desulphurization tower increases, the flue gas velocity, temperature, particle concentration, and water vapour distribution in the bed become more uniform. The relatively stable operating conditions for the gas–solid flow in the desulphurization tower is that the flue gas inlet velocity and temperature are 15 m/s and 393 K, respectively. Under these operating conditions, the pressure loss caused by the venturi accounted for 73.6% of the total pressure loss of the desulphurization tower. When the particle radius is between 0–150 μm, the particle size and the flue gas inlet velocity have the greatest influence on the particle residence time. Finally, the distribution of gas and particles before and after the adjustment of the desulphurization tower is compared, which showed that adjusting the bottom structure of the desulphurization tower could optimize the gas–solid flow.

Numerical simulation study of ionization characteristics of argon dielectric barrier discharge

In order to better analyze the characteristics of particle distribution and its influencing factors in the ionized space during the process of coaxial dielectric barrier discharge, a self-designed two-dimensional axisymmetric structure exciter was used to carry out optical diagnosis, with the electron temperature calculated through Gaussian fitting. A plasma model was applied to conduct research on the discharge process through numerical simulation, with the changes in electron density and electron temperature were analyzed by using different discharge parameters. The research results show that with an increase in discharge voltage, pressure inside the reactor and relative permittivity, the discharge process is promoted. In addition, a rise in current density leads to an increase in the number of charged particles on the surface of the medium during the discharge process, while a rise in discharge intensity causes an increase in the electron density. Electron temperature decreases due to the increased loss of collision energy between particles. These results were confirmed by comparing experimental data with simulation results.

Numerical Investigation of Recommended Operating Parameters Considering Movement of Polymetallic Nodule Particles during Hydraulic Lifting of Deep-Sea Mining Pipeline

Previously conducted studies have established that pipeline hydraulic transport systems are currently the most promising deep-sea mining systems, and the pipeline transport performance of polymetallic nodules is one of the technical priorities. In this paper, a coupled CFD–DEM approach is adopted to numerically calculate the solid–liquid two-phase flow of seawater with polymetallic nodules. Small-scale experiments were conducted to validate the coupled model. Particle dynamics analysis was carried out under different inlet flow rates, feed concentrations and nodule fragmentation levels. The simulation results show that different operating parameters have significant effects on the pipeline transportation process. With low inlet flow rate, high feed concentration, and high percentage of large particles, the particle distribution and motion characteristics show a trend that is not conducive to safe transport. A set of recommended operating parameters for hydraulic transport of polymetallic nodule pipelines was summarized.