Particle Deposition Process Research Articles

Direct observation of particle clustering and gas breakdown in charged granular streams

The dust layer formed by charged particles deposition significantly limit the collection efficiency and stable application of electrostatic precipitators (ESPs). However, the deposition characteristics and re-entrainment mechanism of charged particles in electric field still remain unclear. In this study, a transparent ESP was designed to investigate the dynamic process of charged particle deposition, clustering and gas breakdown in electric field. The results showed that deposited particles will aggregate and gradually grow in chains in high-voltage electric field. The length of chain agglomerates can exceed 10 mm. And interelectrode gas breakdown could suddenly occur, which significantly changed the particle charging characteristics and increased particle emission at the outlet. In addition, a perforated plate was proposed to inhibit the gas breakdown and particle re-entrainment. The mass concentrations of particle re-entrainment decreased by 85.2 % and 79.1 % for the spike electrode and the arista electrode at the applied voltage of 30 kV, respectively.

Investigating the formation of soot in CH4 pyrolysis reactor: A numerical, experimental, and characterization study

Methane pyrolysis is a promising method for eco-friendly hydrogen production, but soot formation and carbon interaction pose challenges for scaling up. Therefore, understanding the dynamics of soot formation and carbon deposition is crucial. This study delves into the intricacies of soot formation in methane pyrolysis under industrially relevant conditions, namely operations at atmospheric pressure, employing a H2:CH4 ratio of 2 and exploring a range of hot zone temperatures (1473 K, 1573 K, 1673 K, and 1773 K) with a 5 s residence time. Utilizing a detailed gas-phase kinetic model with direct carbon deposition reactions, the research adopts the method of moments coupled with a one-dimensional plug flow reactor model to simulate soot formation. The model is validated by characterizing soot particles that were produced in a pyrolysis reactor by means of transmission electron microscopy, Dynamic light scattering (DLS), and Raman spectroscopy. Results show that lower temperatures lead to nucleation-dominated growth, whereas higher temperatures significantly restrain particle growth due to carbon deposition. DLS data indicate a complex balance between particle growth and deposition processes. These findings provide insights into operational parameters that can enhance reactor performance and sustainability in hydrogen production processes by mitigating soot and carbon deposition.

Impacts of Stefan Blowing on Thermophoretic Particle Deposition in Sisko Nanofluid Flow Over a Riga Plate with Soret and Dufour Effects

The proposed framework considers the thermosolutal Marangoni convective flow of Sisko [Formula: see text] nanofluid over a Riga surface with the effects of Stefan blowing and thermophoretic particle deposition. The phenomena of mass and heat are discussed in relation to Soret and Dufour impacts. Electrodes and magnets are arranged on a plate to make up the Riga plate. Since the fluid conducts electricity, the Lorentz force upsurges exponentially in the vertical direction. There are numerous possible uses for this study in different disciplines. The design and production of thin films, coatings, and nanostructured materials can be enhanced by knowledge of how nanoparticles settle onto surfaces under various fluid flow conditions. By optimizing fluid flow and particle deposition processes, engineering insights from this work can guide the development of more efficient heat transfer systems, such as heat exchangers and cooling technologies. The nonlinear governing PDEs are converted into nonlinear ODEs using appropriate transformations. The resultant system of highly nonlinear equations can be solved analytically by using the homotopy analysis method (HAM). The significance of factors on the flow, thermal, and concentration fields are thoroughly explained with the use of tables and figures. Higher Marangoni convection parameter in more effective heat and mass transport within the liquid as well as higher induced flows when the Marangoni convection parameter is increased. A more uniform distribution of these properties throughout the liquid is the result of decreasing temperature and concentration profiles.

Electroless Copper Plating on a Cotton Surface: Effect of Metal Ion Ligand Stability Constant on Reduction Deposition.

Electroless plating facilitates the metallization of nonconductive substrate surfaces, and of note, the precise control of the bath stability constant influences the deposition process of metal particles. In this paper, trisodium citrate, potassium sodium tartrate, nitrogen triacetic acid, thiourea, and ethylenediamine tetraacetic acid disodium were selected as coordination agents, and the effect of the metal ion ligand stability constant on the reduction deposition was studied. Coordination bonds can be established between the Cu2+ and O/N/S particles in the ligand because paired electrons in O/N/S hybrid orbitals tend to occupy empty Cu2+ hybrid orbitals and establish coordination bonds. More importantly, the copper-potassium sodium tartrate ligand exhibits the lowest stability constant and lowest reduction barrier. As an exception, a consecutive Cu-plated coating with an excellent crystallinity property was deposited on the cotton surface when potassium sodium tartrate was used as the coordination agent in the plating solution. The deposition amounts are 55.2% and 74.1% after 1 and 4 h of electroless copper plating, respectively. The surface resistivity of Cu-plated cotton is 0.38 Ω/cm2, and additionally, the surface resistivity ratio before and after 1000 cycles fluctuated between 0.9 and 1.1, indicating that the Cu-plated cotton exhibits outstanding flexibility. In this paper, the deposition rate can be optimized by adjusting the copper particle ligand stability constant in the plating solution, aiming to achieve optimal results.

Research Progress on Numerical Simulation of the Deposition and Deformation Behavior of Cold Spray Particles

It is of significant theoretical and practical value to study the deposition process and deformation behavior of cold-sprayed particles to find the deposition mechanism of cold-sprayed coatings, further improve the coating performance, and expand its application scope. However, observing the deposition process and particle behavior through experiments is difficult due to the brief deposition duration of cold spray particles. Numerical simulation offers a means to slow the deposition process and predict the critical velocity, deformation behavior, bonding mechanism, and residual stress of cold-sprayed particles. This paper uses finite element analysis software, including ANSYS LS Dynamic-2022 R1 and ABAQUS-6.14, alongside various prevalent finite element methods for numerically simulating cold spray particle deposition. These methods involve the Lagrange, Euler, arbitrary Lagrange-Euler (ALE), and Smoothed Particle Hydrodynamics (SPH) to investigate the cold spray particle deposition process. The recent literature primarily summarizes the simulation outcomes achieved by applying these methodologies for simulating the deposition process and deformation characteristics of different particles under varying cold spraying conditions. In addition, the reliability of these simulation results is analyzed by comparing the consistency between the simulation results of single-particle and multi-particle and the actual experimental results. On this basis, these methods’ advantages, disadvantages, and applicability are comprehensively analyzed, and the future simulation research work of particle deposition process and deformation behavior of cold spraying prospects is discussed. Future research is expected to provide a more in-depth study of the micro-mechanisms, such as the evolution of the inter-particle and internal organization of the particles, near the actual situation.

A Roundness Calculation Method and Physical Parameter Analysis of A Porous Medium Model

The rounding degree of particles is an important index of particle morphology. It represents the degree of rounding of the original edges and corners of debris particles. To a certain extent, it can reflect the transportation and deposition process of debris particles and the source properties. Therefore, it is of great significance to explore the rounding law of gravel and the influencing factors of rounding degree for the study of geological sedimentary environment, source analysis and mass transfer process. Therefore, this paper proposes a rounding degree calculation algorithm for fractal porous media model particles with rounding characteristics. Through numerical simulation and theoretical analysis, combined with the geometric parameters of particle morphology, the relationship between particle roundness and area and perimeter parameters is discussed in detail. The results show that roundness is an important factor in the geometric parameters of particles. The change of roundness can significantly affect the geometric shape of particles, and then affect the size and area of particles. It is of great significance for understanding and optimizing the flow characteristics of porous media models.

Printing Completely Conformal Liquid Metal Circuits on Arbitrary Curved Surfaces via Customized Conformal Mask

Owing to the excellent mechanical adaptability to curved surfaces and high circuit flexibility, conformal electronics have been developed for extensive applications including aeronautics and wearable electronics. However, conventional methods for fabricating conformal circuits are often constrained by planar structures, limiting the design flexibility and applicability of electronic devices on more complex and varied surfaces. In this study, we propose a facial approach by combining a 3D‐printed customized conformal mask (CCM) with liquid metal inkjet printing, to establish the completely conformal liquid alloy circuits printing technique on arbitrary curved surfaces. We develop a two‐dimensional transient mathematical model to simulate the particle deposition process during inkjet printing and predict the form of the circuits on curved surfaces. Moreover, we characterize parameters such as line resistance and cross‐sectional morphology of liquid metal circuits on both deformable and non‐deformable surfaces. Various conformal liquid metal circuits, such as contour lines, expressions, text patterns, LED array illumination patterns, and multi‐channel pressure array intelligent skin on curved surfaces are demonstrated. Compared to traditional conformal electronics manufacturing methods, this new approach offers the advantages of simple processes, flexibility, low cost (within $0.01/cm2), and high efficiency (exceeding 1cm2/s), making it suitable for mass conformal electronics production.This article is protected by copyright. All rights reserved.

Motion of fine particles in a temperature gradient: Experiment, visualization, and numerical simulation studies

The migration and deposition processes of fine particles under the influence of temperature gradients and fluid flow are widely prevalent. Investigating the mechanisms of particle interactions in these processes contributes to the development of efficient dust removal techniques. In this work, experimental and numerical studies of particle motion in temperature gradient fields are conducted. The research encompasses both qualitative and quantitative analyses of particle motion influenced by thermophoresis and particle diameter. Qualitative analysis reveals that the motion characteristics of particles are jointly determined by gravity, drag force, and thermophoretic force, and the diameter range that exhibiting a notable influence of the thermophoretic force is 20–30 μm. Quantitative analysis shows that the manifestations of deposition and diffusion become more evident with an increasing temperature gradient. For instance, in comparison to the working condition with ΔT = 0 K and dp = 20 μm, the deposition mass increases by approximately 23% when ΔT = -15 K; conversely, it diminishes by about 11% when ΔT = 15 K. Additionally, the Discrete Phase Model (DPM) is employed to simulate the motion of gas-solid flow. This study presents a novel visualization system to observe particle motion in gas-solid systems to elucidate the mechanisms underlying the thermophoretic effect and establish a robust theoretical foundation for thermophoretic dust removal technology.

Significance of heat generation and thermophoretic particle deposition in Marangoni convective driven boundary layer flow of cross nanofluid with activation energy

The thermo-solutal Marangoni boundary layer flow has been studied because it has a number of real-world uses, such as drying silicon wafers, applying thin coats of paint or glue, employing adhesive in heat exchangers, and growing crystals in space. The physical phenomenon of Cross (FeSO4−(CMC−H2O(<0.4%)) nanofluid flow in a porous medium with thermophoretic particle deposition and Marangoni convective flow is explored. Non-Newtonian Cross nanofluid flow is explored in relation to the effect of activation energy. The process of thermophoretic particle deposition, which is important in both electrical engineering and aero-solution, is one of the most fundamental methods for transferring small particles across a heat gradient. Cross nanofluid containing FeSO4 as nanoparticle, and based fluid is (CMC- water). Using the appropriate similarity variables, the set of governing PDEs is transmuted into a set of ODEs. The RKF-45th method is used to numerically solve these simplified equations. The graphic examination of the concentration, velocity and thermal fields is developed for the embedded non-dimensional characteristics. By raising the Marangoni ratio parameter, the surface tension gradient gets stronger, causing the induced flows to get stronger through the liquid more effectively. The concentration and thermal profiles fall with an enhancement in Marangoni ratio parameter.

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.

Prediction of grain size and dislocation density in the cold spraying process using a dislocation-based model

The cold spray particle deposition process was simulated by modeling the high-velocity impacts of spherical particles onto a flat substrate at different velocities. In addition to simulating the single particle, this study also employed a unique simulation technique to predict the evolution of the material's microstructure under real process conditions. A dislocation-based model was implemented as a VUMAT subroutine to model the microstructure. Additionally, Python scripting was also utilized in the multi-particle impact simulation to create particles and assign velocity and interaction randomly. The relationships between stress-strain values and material microstructure are linked together. By using this model, calculations were done for the equivalent plastic strain, dislocation density, and grain size in the particle, substrate, and interface. At the interface, there were high levels of plastic strain and strain rates reaching up to, which formed a bond between the particles and the substrate. It was found that a minimum plastic strain of approximately 1 is needed to create this bond. At velocities exceeding a critical velocity, a jet was produced. The particle grain size in regions distant from the interface measured between 200 and 500 nm, which is in good agreement with the experimental results. The smallest grain size was observed at the interface, measuring 140 nm. The validation outcomes demonstrated that the suggested model effectively replicates the cold spraying process. As a result, the suggested model has the capability to predict and evaluate the changes in the material's microstructure during the cold spraying process using various factors.

In situ multi-perspective scanning of 3D particle deposition on flat plates with film cooling and determination of practical model parameters

A practical strategy for three-dimensional morphology measurement in the particle deposition process is of great importance to deepen the understanding of deposition physical processes. Due to the methodology limitations, it is difficult to obtain the formation process of deposition morphology. In this work, an in situ multi-perspective scanning (MPS) method using structured light was developed to capture the formation process of deposits. The point cloud registration algorithm was adopted to reconstruct the deposition morphology. Based on the validation results of Vernier caliper, the MPS method provides an uncertainty of ±0.056 mm at 4 mm. To verify the potential application of in situ measurement in gas turbine diagnostics, MPS method was preliminarily applied to the flat plate test with film cooling in particle-laden flow. The application demonstrated that this method successfully reconstructed the deposition morphology on a flat plate in the presence of film cooling. Furthermore, the obtained morphology results revealed that deposition roughness lied in the 0.35–0.56 mm and increased with an increase of blowing ratio. Additional comparisons with film cooling effectiveness showed the deposition distribution was related to the film cooling process. The detailed three-dimensional (3D) deposition morphology determined the mean curvature and mass of deposits, which may improve the prediction accuracy of deposition models in numerical simulations.

Refined interpretation of electron temperature response to neutral beam injection at DIII-D

Accurate particle and power deposition profiles of neutral beam injection (NBI) are essential to transport studies, and that information is usually acquired through Monte Carlo simulations with a given collisional model. The deposition process of the energetic beam particles leads to the informative electron temperature (Te) evolution trajectory, which can be captured by electron cyclotron emission (ECE) system due to its good spatial and temporal resolution. Previously, some work has been done to interpret the Te responses to the pulsed NBI as a linear heating source with Fourier-based techniques, although that approach fell short when the fast ion slowing-down time becomes significant (∼100 ms). It has been observed in DIII-D that the modulated NBI pulses (10–50 Hz) reduce local core Te values ∼0.1 keV through cold electron dilution in high-Te (&amp;gt;2 keV) plasmas alongside accumulative heating. Here, a novel approach to interpret the Te response to NBI was developed by linearizing and modeling the detailed Te evolution trajectory using coherently averaged ECE data based on the different time scales of the terms in the local power and particle balance equations. The technique does not require absolute calibrations of ECE and is independent of collisional models. The resulting beam deposition profiles show good consistency and reasonable agreement with Monte Carlo calculations based on the atomic data from the Atomic Data and Analysis Structure (ADAS). Local electron density response measured by Thomson scattering (TS) also suggests the same features when the beam pulse is large enough for that diagnostic to resolve. The remaining discrepancies are also discussed.

Solid-state cold spray welding: Evaluation and future direction

Welding is an important manufacturing process for joining complex parts. Despite their widespread use, there exist some drawbacks in the existing liquid-state (e.g., formation of undesirable heat-affected zones around weld area) and solid-state (e.g., high equipment and tooling costs, low production rates, and difficulty in joining intricate geometries) methods. These limitations continually spur the search for new joining processes to improve existing welding methods or develop new ones that circumvent these limitations. To provide a “greener” and low-cost alternative to the traditional welding processes that often produce “soft” heat affected zones (HAZs), we develop and evaluate the expansion of cold spray process—a solid-state high-velocity particle deposition process—to solid-state welding, a process we term cold spray welding (CSW). Using well-defined processing parameters, we cold spray welded (CSWed) AA 6061-T651 plate and compared the results with Tungsten inert gas (TIG) welded counterpart. Although TIG-welded samples exhibit higher tensile properties than CSWed samples (at least based on the CS processing parameters used in this study), our findings show that CSW indeed circumvents major drawbacks in traditional welding processes, including negligible microstructural alterations and the inhibition of deleterious phase transformation and suppression of deleterious HAZ. The examination of CSWed parts reveals low yield strength is connected to ubiquitous microvoids that are formed due to lack of metallurgical bonding; these microvoids act as microcrack initiation sites. We proceed to establish a failure mechanism in the CSWed part to provide direction for future optimization.

Electrostatic Powder Coating as a Novel Process for High‐Voltage Insulation Applications

A novel strategy for manufacturing of the main insulation of high‐voltage rotating machines is presented. The developed process is based on established electrostatic powder coating equipment. Using complete automation enables the precise and reproducible application of homogeneous powder coating layers. Individual layers can be stacked by process repetitions to achieve a desired layer thickness. This coating strategy alters the particle deposition process by introducing additional capillary bridges that significantly increase powder adhesion. A systematic parameter study is performed to provide process–structure relations connecting various process parameters with the resultant coating thickness and homogeneity. The parameters of the developed coating process are iteratively improved to maximize coating homogeneity and minimize defect density, the most critical parameters in high‐voltage insulation applications. The obtained powder coatings with a target thickness of 1.5 mm are subjected to electrical testing to examine the partial discharge activity as a key criterion for a functional insulating coating. The measurements reveal no significant partial discharge activity up to an electric field strength of 10 kV mm−1, demonstrating that this novel strategy for the production of the main insulation of high‐voltage rotating equipment surpasses the state‐of‐the‐art process in terms of partial discharge activity.

Numerical analysis of catalyst particle deposition characteristics in a flue gas turbine with an improved particle motion and deposition model

To more accurately understand and predict the deposition behavior of catalyst particles in the flue gas turbine cascade, test and numerical combined study is performed in this paper. Based on the systematic analysis of the deposition process and physical mechanism of the catalyst particles, the traditional DRW model, critical velocity particle deposition model and removal model were corrected with the user defined function custom function and validated with the actual deposition morphology. On this basis, the effects of the particle Stokes number and flue gas parameters on the particle deposition characteristics of the flue gas turbine cascade were detailed investigated. The results show that the revised DRW model, critical velocity and removal model can more accurately predict the deposition location and deposition rate of particles in the turbine cascade. With the increase in the Stokes number of particles, the average particle impact rate on the blade surface gradually increased, while the average deposition rate showed a trend of first increasing and then decreasing. The average deposition rate of particles in the rotor blade surface is roughly twice as high as that in the stator surface. With the increase of the flue gas expansion ratio, the deposition rate of particles less than 3 μm gradually increases, while the deposition rate of particles greater than 3 μm tends to decrease. In addition, the change in the flue gas expansion ratio has no obvious effect on the particle deposition distribution in different size ranges.

A particle deposition model considering particle size distribution based on the Eulerian approach

The problem of ash deposition on heat exchange surfaces is one of the main causes hindering the safe and efficient operation of conventional boilers. Hence, looking into the particle deposition characteristics on heat transfer surfaces as well as the formation process and the deposition mechanism is essential. In this study, a particle deposition model considering the particle size distribution based on the Eulerian approach is presented to predict the dynamic deposition process of multi-sized particles on the surfaces of heat exchange tubes. The model harnesses the advantages of the Eulerian approach and takes into account the particle size distribution as well as the interaction between them. By coupling computational fluid dynamics (CFD) analysis with the population balance model, and the embedding user-defined function code with the deposition model, the deposition characteristics of the multi-sized particles are predicted. It is established that the simulation findings of this model, as opposed to models for average-sized particles, are in greater accord with the experimental data by comparing the model predictions against published experimental results, with the average relative deviations are reduced by 9.28%, 8.11%, and 7.14%, respectively. The weighted average of the latter three dimensionless deposition velocities of multi-sized particles are all greater than those of average-sized particles. Moreover, the net deposition mass of multi-sized particles is 9.34% higher than that of average-sized particles.

From successive deposition to clogging of poly(styrene) particles in the cross-flow through a T-shaped microchannel

Predicting and mitigating pore clogging are complex and challenging problems in fluid transport and filtration systems. This paper investigates the mechanism of particle deposition and pore clogging in a T-shaped microchannel under cross-flow conditions, using polystyrene particles dispersed in the glycerol solution. In this study, the flow rate and glycerol concentration are systematically controlled to analyze the effect of hydrodynamic stress on the clogging mechanism. Through flow visualization and image processing, the study identifies the step-by-step process of particle deposition and accumulation including the phenomena like “edge deposition”, “growth of deposition”, “rolling”, and “agglomerate breakup”. This study suggests that there is a critical stress that inhibits particle deposition and prevents pore clogging, and this stress is determined by the balance between the hydrodynamic force and the colloidal interaction force. The study also quantifies the clogging with the “blockage ratio” and “deposition ratio”, and shows that the stress correlates with the number of particles required for clogging. The methodology and findings of this study can aid in designing flow operating conditions to control particle deposition and clogging in various filtration systems and can serve as a critical first step toward understanding the behavior of particles in complex fluids with viscoelastic properties.

Numerical simulation of wear particle deposition in ferrograph based on coupled analysis of magnetic, fluid and solid field

Ferrography is a significant means of wear particle detection for mechanical equipment. In view of the issue that the wear particle deposition process by a ferrograph is difficult to accurately adjust to avoid accumulation or escape, the deposition behavior of wear particles coupled with the magnetic, fluid and solid field in a ferrograph is studied by the finite element method. The wear particle force and its deposition principle are first analyzed, and the theoretical deposition law is obtained. By building 3D finite element model, setting the magnetic, flow field and wear particle parameters, the coupled simulation based on the particle tracking is carried out. According to the process of wear particles flowing out of the oil tube and then depositing on the ferrogram slide, the effect of oil pressure, viscosity, density, ferrogram slide inclination angle, distance between oil tube and ferrogram slide and the particle release mode on the particle deposition behavior is studied. Based on the velocity and displacement of particles, the reasonable parameter ranges are obtained, and the sensitive variables are determined. In order to verify the numerical law through experiments, the area and perimeter of wear particles are adopted, meanwhile the oil viscosity is selected as the adjustable parameter, and the tested results prove the numerical simulation correct.

Numerical simulation on the deposition characteristics of MSWI fly ash particles in a cyclone furnace

In melting municipal solid waste incineration (MSWI) fly ash by cyclone furnace, the deposition characteristics of particles affect the slag flow and the secondary MSWI fly ash formation. In this study, the composition mechanism based on critical viscosity is selected as the particle deposition model to predict the deposition and rebound of particles on the furnace wall. The Riboud model with an accurate viscosity prediction performance is selected, then the particle deposition model is integrated into a commercial computational fluid dynamics (CFD) solver through the user-defined function (UDF) to realize the coupling of particle motion and deposition process. The results show that under the same case, the deposition rate decreases obviously with the increase of MSWI fly ash particle size. And the escape rate reaches a maximum at particle size 120 μm. Controlling the particle size of fly ash particles within 60 μm can effectively reduce the generation of secondary MSWI fly ash. During the forward movement of the fly ash inlet position, the escape of MSWI fly ash particles with large particle sizes has been significantly weakened. This measure not only lowers the post-treatment cost but also dramatically reduces the pretreatment step of MSWI fly ash before the melting and solidification process. In addition, the deposition rate and quality will reach the maximum values, respectively, along with gradually increasing MSWI fly ash input flow. Overall, this study has the guiding significance for reducing the pretreatment steps and post-treatment costs of MSWI fly ash by melting in the cyclone furnace.