Particle Deposition Characteristics Research Articles

Migration and Deposition Characteristics of Sand Particles on Mesh Filter Surfaces in Water-Saving Irrigation Systems: Evidence from Simulation and Experimental Verification

Migration and Deposition Characteristics of Sand Particles on Mesh Filter Surfaces in Water-Saving Irrigation Systems: Evidence from Simulation and Experimental Verification

Investigation of inter-subject variation in ultrafine particle deposition across human nasal airways: A study involving children, adults, and the elderly

The airflow and particle dynamics in adult nasal airways have been extensively investigated, but the impact of age-related anatomical changes in children and the elderly remains underexplored. This study systematically investigates age-related anatomical variations and associated influence on nasal airflow dynamics and ultrafine particle deposition characteristics by using Computational Fluid-Particle Dynamics (CFPD) approach. Numerical simulations were conducted for 9 healthy nasal subjects spanning a wide age range. 6 Nasal subjects from the Development Group were used as the primary models for data analysis and deposition correlation development, while 3 subjects from the Validation Group were used to validate the reliability of the derived total and subregional deposition correlations. Our results reveal distinctive variations across age groups. Specifically, the elderly and children exhibit unique patterns that differ from those of young adults. While total deposition efficiency differs significantly between children and adults, filtration efficiency in the subregion with most deposition, main respiratory, remains consistent. Lastly, overall and subregional empirical equations for deposition efficiency were developed by incorporating the combined diffusion parameter, Sca∆b, corroborating the use of geometrical characteristic parameters for each specific subject in predicting nasal deposition efficiency across different age groups. Our findings are expected to improve the predictive nanoparticle exposure analysis in nasal airways across different age groups, thereby improving the respiratory health for individuals throughout the life span.

Effect of different PV modules surface energies and surface types on the particle deposition characteristics and PV efficiency

The particle deposition behavior of solar photovoltaic (PV) modules and its effect on PV efficiency were numerically investigated using computational fluid dynamics (CFD) methods. The surface flow field of PV modules using the shear stress transfer (SST) k-ω model with a user-defined function (UDF) for the development of entrance boundaries is predicted. A UDF coupled discrete phase model (DPM) that takes into account wall bounce and hydrophobic properties is used to predict particulate deposition in the flow field. Mesh independence and average pressure coefficients are verified. The effects of particle diameter, boundary type, surface energy and surface type on particle deposition of PV panel and PV efficiency are investigated. The results show that the smaller the surface energy γ, the smaller the particle deposition rate. At dp = 150 μm, γ = 0.001J/m2, it showed that the most significant reduction of 427.3 % in particle deposition rate compared to the trap boundary type, and γ = 0.001J/m2 showed a 210 % reduction in particle deposition rate compared to γ = 0.1J/m2. However, at dp ≤ 50 μm, the change in surface energy has little effect on the deposition rate. The effect of convex PV modules on particle deposition is more obvious at low surface energy (γ ≤ 0.001J/m2) compared to planar. The reduction in PV efficiency caused by particle deposition at different surface energies is predicted using an empirical model of PV output reductions developed by the researcher.

Study on Flow Heat Transfer and Particle Deposition Characteristics in a Kettle Reboiler

Study on Flow Heat Transfer and Particle Deposition Characteristics in a Kettle Reboiler

Study on the deposition characteristics of fine particles at local components in air conditioning ventilation ducts

Air conditioning ventilation ducts are widely used in contemporary buildings. The change of airflow direction in the ducts local components can easily lead to the deposition of particles, which can easily form a secondary source of indoor air pollution and have an adverse effect on human health. Based on this, this paper utilizes the existing experimental data to validate the numerical simulation. The Reynolds stress turbulence model combined with the method of enhanced wall function was used to investigate the deposition characteristics of fine particles in different local components. For the first time, local deposition rates and deposition hotspots were proposed to analyze the simulation results. The results show that the local deposition rate of the particles with a particle size of 1μm do not differ much on each wall surface, and the particles are deposited more uniformly on each wall at the local components, with a difference of less than 10 %, and the maximum local deposition rate is on the outer wall of the local components. When the particle size is larger than 10μm, the local deposition rate on the outer wall of the local component increases significantly, with a maximum increase of 23.3 % (compared to 5μm particles), and the maximum local deposition rate increases slowly with increasing air velocity, with a maximum increase of less than 8 %. The effect of increasing particle size on the maximum local deposition rate is much greater than the increase in air velocity. With the increase of air velocity and particle size, the deposition hotspots of both the 90° bend and the T-type tee duct migrate to the middle of the wall, and the deposition hotspots of the 4-way duct migrate to the inside of the wall.

Comparing Deposition Characteristics of Various Embolic Particles Using an In Vitro Prostate Microvasculature Model

PurposeTo compare spatial distributions of radiopaque glass (RG) microspheres, tris-acryl gelatin (TAG) microspheres, and polyvinyl alcohol (PVA) nonspherical foam particles within a planar in vitro microvascular model of the hyperplastic hemiprostate. Materials and MethodsA microvascular model simulating hyperplastic hemiprostate was perfused with a water-glycerin mixture. A microcatheter was positioned distal to the model’s prostatic artery origin, and embolic particles (RG, 50 μm, 100 μm, and 150 μm; TAG, 100–300 μm and 300-500 μm; and PVA, 90–180 μm and 180–300 μm) were administered using a syringe pump. Microscopic imaging and subsequent semantic segmentation were performed to quantify particle distributions within the models. Distal penetrations were quantified statistically via modal analysis of the particle distributions. ResultsMaximum distal penetration was observed for RG microspheres of 50 μm, followed by RG microspheres of 100 μm and then TAG microspheres of 100–300 μm and RG microspheres of 150 μm. TAG microspheres of 300–500 μm, PVA particles of 90–180 μm, and PVA particles of 180–300 μm exhibited the lowest distal penetrations. The distal penetration metrics between groups were significantly different (P < .05) except between TAG microspheres of 100–300 μm and RG microspheres of 150 μm and between PVA particles of 90–180 and 180–300 μm. ConclusionsComparing the spatial distributions of embolic particles in an in vitro microvascular model simulating the hyperplastic hemiprostate revealed that noncompressible particles and those with narrower size calibrations and smaller relative diameters exhibited higher degrees of distal packing. The embolization front was less distinct for particles with wider size calibrations, which resulted in smaller, more distal emboli along with larger, more proximal emboli. Both PVA particles and TAG microspheres of 300–500 μm exhibited relatively low overall distal penetration.

Design and optimization of gradient fibrous media using the method of moments

The goal of this work is to optimize the deposition mass distribution of polydisperse particles inside the fibrous media by modifying the distribution of the fiber packing density across filter depth. Two types of gradient fibrous media with linear and exponential fiber packing density distribution along the flow direction were derived. The method of moments was employed to study the transport and deposition characteristics of polydisperse aerosol particles inside the fibrous media. The reliability of the calculated results by the method of moments was confirmed by the numerical simulations based on the discrete phase model (DPM). Results indicate that the gradient fibrous media allows more particles to transport and deposit into the interior of the fibrous media, which improves the uniformity of particle deposition distribution across filter depth. There exists an optimal fiber packing density distribution ratio for the gradient fibrous media where the non-uniformity of deposition mass distribution of polydisperse particles across filter depth is minimized. In this way, uniform deposition distribution along the flow direction can be generally achieved by optimizing the fiber packing density distribution, which will contribute to the optimal design of microstructures for the fibrous filter.

A CFD numerical simulation of particle deposition characteristics in automobile tailpipe: power abatement pathways

The study of the movement of pollutants through ducts facilitates the assessment and control of ambient air quality problems (AQ). Among other things, understanding the deposition and distribution of particulate matter in elbows is important for practical engineering applications. In this study, the turbulent flow field and particle deposition in a 90° bend is investigated using RANS simulation. The RNG k-ε turbulence model was employed to calculate the airflow flow field and the discrete phase model (DPM) was used to simulate the particle phase motion. Where for the discrete phase, the Discrete Random Wander (DRW) model was considered and the deposition of particles with sizes of 1, 3, 5, 10, 20, and 40 μm in the flow field was investigated separately. Grid-independent validation of the models used in the simulations was performed. The effects of inlet velocity, particle size, and direction of gravity on the flow field and particle deposition in the elbow were considered. The results show that the flow field in the bend is strongly influenced by the above parameters. Among them, the turbulent disturbance in the bend section is the most intense, with high turbulent energy value, and it is also the region with the largest energy loss. The inlet velocity is negatively correlated with the deposition rate, and the particle size is positively correlated with the deposition rate.

Effect of gas-solid flow parameters and fracture structure parameter on particle deposition characteristics in the mining-induced fracture

The particle deposition in mining-induced fracture is an important reason for the sudden drop in gas drainage flow. In this study, particle deposition characteristics in fracture were investigated. The results showed that the particle deposition bed had prominent regional distribution characteristics along the axial direction of the fracture, and a humped distribution of the particle deposition height was observed along the radial direction of the fracture. In addition, the mechanism of the influence of the operating parameters of the gas-solid flow and the fracture shrinkage ratio factors on the particle deposition scale in the fracture differed fundamentally. The operating parameters of gas-solid flow mainly affected the deposition range of the transitional deposition bed. In contrast, the fracture shrinkage ratio mainly affected the deposition range of the local and transitional deposition beds. The results can provide guidance for understanding the particle deposition characteristics in fractures with a fracture shrinkage structure.

A CFD Study of Particulate Deposition on Dimple-Type Flue Walls of Coal-Fired Power Plants

The study of particle deposition in bends is always a continuous challenge in various engineering and industrial applications. New types of channels with special microstructures on the surfaces can be effective in modifying the flow field structure as well as particle deposition in channels. In this study, a 90° circular bend with a convex dimple structure was used, and the flow field and the deposition of particles in the channel were analyzed; the Stokes numbers (St) used were 0.016, 0.355 and 1.397. The reliability of the model was ensured by mesh-independence validation as well as speed validation. In a 90° bend channel with convex dimples, the temperature distribution, particle deposition distribution, flow structure and secondary flow were examined. The effects of the number of convex dimples and St in the bend on the flow field structure and particle deposition characteristics were analyzed. The results show that the main factors affecting the deposition characteristics of particles in bends are St, gravitational deposition, thermophoretic force, turbulent vortex clusters and secondary flow distribution. The effect of St is more pronounced, with the deposition rate increasing as the St increases, and the deposition location of the particles is mainly clustered on the outside of the bend structure of the elbow.

Study on the Particle Deposition Characteristics of Transpiration Cooling Structures with Sintered Wire Mesh.

Transpiration cooling based on a porous structure has an ultra-high cooling efficiency, which is expected to be one solution to improve the cooling technology of aero-engine turbine blades. However, particulate impurities in the gas flow channel continue to deposit on the surface of turbine components, blocking cooling holes, which causes great harm to the cooling of turbine blades. In this study, a sintered metal mesh plate was selected as the transpiration cooling structure, and the evolution of particle deposition quality and deposition thickness on the transpiration cooling surface with time, as well as spatial distributions of particle deposition thickness at different times, were explored through experimental and simulation methods. The results showed that, with the increase in spray time, deposition quality and maximum deposition thickness of the transpiration cooling surface gradually increased. Along the main-stream direction, when spray time was short, deposition thickness was higher in a narrow range upstream of the experimental specimen. With the increase in spray time, deposition thickness gradually decreased along the direction of the transpiration cooling mainstream. In the spanwise direction, when spray time was very short, deposition thickness in the spanwise direction was more consistent and, after spray time increased further, the deposition thickness distribution began to tend to a "&cap;"-type distribution. It can be seen from the simulation results of the metal wire mesh particle deposition that particles were easily deposited on the windward side of the metal wire in the main-stream direction, which agreed with the experimental distribution characteristics of the metal wire mesh deposition. Moreover, the increase in blowing ratio reduced the deposition of particles on the wall of the metal wire mesh.

Analysis of the correlation between mechanical and physicochemical properties of particles based on a diesel oxidation catalytic system

The mechanical and physicochemical properties of diesel engine exhaust particles before and after diesel oxidation catalyst (DOC) treatment are analyzed. It is considered important to explore the interrelationships between these attributes in order to understand their relevance. Understanding of these properties provides insights into the deposition characteristics of particles within the system and the evolution of the particles after the DOC treatment, which may help the selection of appropriate aftertreatment strategies. In this paper, particle samples were collected before and after the DOC to explore the variations in the mechanical and physicochemical properties of the particles under different operating conditions. Atomic force microscopy, thermogravimetric analysis, transmission electron microscopy, and Raman spectroscopy were employed to investigate the attraction force, adhesion force, adhesion energy, oxidative reactivity, primary particle size, nanostructure, and graphitization degree of the particles. The results indicated that under post-injection conditions, the attraction force, adhesion force, and adhesion energy of the particles increased significantly. However, when the particles passed through the DOC, these properties decreased to varying degrees. By analyzing the combination of physicochemical properties, it was determined that the attraction force of the particles was primarily influenced by the primary particle size and the particle's graphite structure. The adhesion force was found to be closely related to the content of soluble organic matter. Additionally, the soluble organic matter affected the degree of particle agglomeration by altering the adhesion energy of the particles.

Numerical study on particle deposition characteristics of turbine blade with cooling film

The aircrafts face the serious issue of particle deposition on blade surface when inevitably working in the dust environment. A simplified C3X turbine blade within film holes is selected to investigate the particle deposition characteristics on blade surface. The EI-Batsh deposition model is applied to observe the particle deposition process and the dynamic grid method is used to rebuild the surface morphology of deposit layer. It is found that the particle deposition rate rises with the increasing particle size due to the increasing impacting frequency of particles. But the deposition rate gradually decreased when the particle diameter increasing to the constant value (15 μm). The particle density has a little influence on particle deposition in comparison to the particle size, especially when particle density increases to 1700 kg/m3, density no longer affects the deposition rate. Besides, the deposit layer on blade surface leads to the increase of particle deposition rate due to the increasing roughness when St < 1.

Effect of particle size distribution on the transmission efficiency of atomized water to the tracheal tube

Ultrasonic atomization is a widely used technology. As the atomization device, lead zirconate titanate (PZT) and lithium niobate (LN) are comparatively investigated through experimental and numerical schemes. However, knowledge on a profitable scheme by which to efficiently deliver the atomized particles into the tracheal tube remains unclear. In this study, the physical difference of the transmission efficiency of water particles atomized by PZT and LN devices was measured. The water particles atomized by PZT and LN were injected into a human airway model including a nasal cavity and bronchial tube. The distribution of the amount of transmitted particles deposited at each of the monitoring positions was then estimated using the results of image analysis of color intensity. As a result, the atomized particles of the PZT device, which produced larger particles than the LN device, were more strongly affected by inertia and tended to be deposited at the area closer to the entrance of the nasal cavity. In contrast, the particles produced by the LN device tended to be transmitted deeper into the trachea. The experimental results indicated that the particle size distribution of PZT and LN, which have quite different maximum sizes of particles, largely influences the spatial distribution characteristics of particle deposition along the airway from the nasal cavity to the trachea.

Numerical simulations on film cooling performance of turbine blade before and after particles deposition

In the present study, a C3X turbine blade with film holes is selected to investigate the effect of blowing ratio on particle deposition and heat transfer characteristics on the blade surface. The deposition characteristics of the blade surface are obtained based on the EI⁃Batsh particle deposition model, and the surface morphology of the deposited layer is reproduced using the dynamic mesh model. The results show that the particle deposition mainly occurs at the leading edge and pressure surface of the blade, but the large-size particles will be deposited on the suction surface due to rebound. The effect of blowing ratio on large-size particles is more obvious, and the deposition rate tends to decrease and then increase with the increase of blowing ratio. Within the range of blowing ratios in this paper, particle deposition leads to an improvement in the cooling efficiency of the air film in the pressure surface along the flow direction near the air film hole region, but a significant decrease in the cooling efficiency near the trailing edge region. Overall, particle deposition caused an increase in overall blade temperature.

Numerical study on transport and deposition characteristics of particles associated with heat setting process in opposed jet flow field

The transport and deposition of particles accompanying the heat setting process in the opposed jet air supply system have a significant impact on the equipment safety. This paper used the Realizable k–ε model to simulate the flow field distribution of the impinging jet and the Lagrange method to track the trajectory of particles, by considering factors, such as jet velocity (7–13 m/s), oven temperature (413–473 K), and particle size (1–30 μ m ) changes, the instantaneous force process of particles was analyzed and their deposition mechanism was revealed. The numerical results have been well validated, with the root mean square error of within 10%. The results indicate that the flow field form of the opposed jet significantly affects particle placement on the surface of the air duct, the maximum turbulent vortex structure appears at the inlet of the air duct on both sides of the protruding nozzle, enhancing the capture of particles. Under the influence of gravity, the lower surface of the air duct becomes the main deposition surface, this phenomenon becomes more pronounced as the particle size increases and the maximum deposition rate difference between the upper and lower layers is 37%. The number of particles deposited on the rear end of the air duct is greater than that on the front end, and the deposition rate decreases with the increase in jet velocity. In the initial stage, a temperature gradient appeared in the machine room, which provided upward lift for the particles, resulting in more small diameter particles ( d p < 10 μ m ) depositing on the upper surface of the air duct. The results can provide theoretical support for the fire prevention and pollutant purification of equipment, such as heat setting machines.

Hybrid manipulation of inkjet-printing deposition pattern of high particle concentration droplet by means of thermal and binary solvent effects

Inkjet-printing of functional material is a well-known drop-on-demand technology used in a wide range of modern applications, such as flexible electronics, biomedical testing, etc. It enables to deliver small amount of materials as ink to the specific location on target substrates. However, it is challenging to precisely manipulate the particle deposition characteristics which is crucial to the quality of the fabricated device. Unlike the traditional passive methods by manipulating the nanoparticle, solvent or substrate surface condition, we propose a passive-active hybrid manipulation method by employing a binary mixture solvent and heating substrate. In this paper, the effects of the solvent mixing ratio, the substrate temperature, the substrate thermal properties on the deposition characteristics of high concentration ITO nano-ink were investigated. Interestingly, we have observed a transition of the classic slim coffee-ring to a fat coffee-ring with a large ring width. A dimensionless number was developed to predict the transition boundary from fat-ring pattern to slim-ring pattern. Finally, the phase diagrams of deposition patterns on three substrates were developed, which were convenient for deposition pattern manipulation in real applications.

The CPFD approach was used to investigate the particle flow characteristics and auxiliary air inlet in an ash transfer pipe

Numerical simulations for the air-solid two-phase flow in a horizontal pipe with a diameter of 125 mm and a length of 10 m were carried out using the Computational Particle Fluid Dynamics (CPFD) method. The deposition characteristics of particles in the pipe were investigated at various inlet flow rates and velocities, and the effect of the auxiliary inlet with different structural parameters on the evacuation of particles in the pipe after the auxiliary inlet was added to the horizontal pipe was compared. The results show that when the volume fraction of particles in the tube is less than 0.6, the flow of particles is relatively stable, and when the volume fraction of particles is greater than 0.8, the particles are seriously deposited and easily form a blockage; the auxiliary air inlet speed is proportional to the effect at the same tilt angle; when the air inlet speed is constant, the auxiliary air inlet angle increases from 35° to 55°, the effect of auxiliary air inlet increases and then decreases, and the effect of auxiliary air inlet reaches its peak at around 45°. The study's findings have implications for long-distance particle transport in horizontal pipelines.

Effects of water-based SiO2 nanofluids on the wettability of coal dust and particle deposition characteristics

Coal wettability plays a crucial role in the prevention of coal mine dust and associated disasters such as coal and gas outbursts. Water-based SiO2 nanofluids have emerged as promising wetting agents because of their sustainable wetting effects on coal. However, the current research on the wetting characteristics of nanofluids has predominantly focused on small coal fragments, with limited studies on coal dust. This study aims to investigate the influence of water-based SiO2 nanofluids with varying particle concentrations on the wettability of coal dust via physical experiments. The findings revealed that the modification by nanofluids significantly reduced the contact angles of the coal dust particles with the particle size ranges of 60–80, 80–100, and 100–150 mesh, compared to the initial contact angles. Moreover, higher particle concentrations resulted in smaller contact angles. Notably, the wetting effects of the nanofluid modification on coal dust were particularly prominent for larger particles. Furthermore, compared with water immersion, nanofluid modification demonstrated a significantly more positive impact on the wettability of coal dust. Notably, the SiO2 nanoparticles exhibited a wide distribution and substantial adsorption capacity on the coal surface, enabling the formation of a hydrophilic structure coverage. This study contributes to a comprehensive understanding of the wetting behavior of coal dust when exposed to water-based SiO2 nanofluids. These findings underscore the potential of nanofluids to enhance coal dust prevention and control, and provide valuable insights for future research in this field.

Characteristics of Coal Dust Deposition in Boiler Tail Gas Pipelines

Coal dust deposition in boiler tail gas pipelines can significantly affect boilers’ thermal and energy efficiency. This study investigates the deposition characteristics of coal dust particles in boiler tail gas tubes in variable cross-section tubes. Numerical simulations were performed using the Reynolds Stress Model and the Discrete Particle Model. User-defined functions coding is used to construct the particle deposition model in the particle deposition model. The study analyses the distribution of turbulent kinetic energy locations in the gradient tube, compares the distribution of particle deposition on its wall, and concludes that the deposition distribution of coal dust particles in the gradient tube is slightly different for different particle sizes. Smaller particles have a higher deposition efficiency in equal cross-section pipes than larger particles. Particle size also has a significant effect on pipe taper and expansion. The results of this study can provide theoretical guidance for optimising the design of boiler tail gas pipelines, improving energy efficiency, and reducing environmental pollution.