Separation Of Particles Research Articles

The Halbach and alternating polarity linear magnets array are designed for microparticle separation, based on magnetophoresis

Abstract Particle separation using magnetophoresis requires an inhomogeneous magnetic field which affects the microparticle. The more changes in the magnetic field, the greater the magnetic force. The changes could exist in various ways. In this article, the change to produce a more intensive inhomogeneous magnetic field is generated by rotating the magnets to a specific degree. The analyses are done for three-state magnet arrays. For this purpose, a device is fabricated and the mentioned arrays are embedded in it. First, the results are simulated. The mathematical piecewise algorithm is used to validate the simulation. By examining the states in the fabricated device the experimental results are extracted. Overall, the results demonstrated that the Halbach and alternating polarity linear arrays (both 90, and 180 degrees) have better efficiency and throughput than the regular design array (without magnet rotating). The Halbach designs are illustrated with approximately the same results. However, in alternating polarity linear array, 180 degrees the particle capturing rate stood in a better place than the other design. 

Effect of the Cross-Sectional Geometry of the Mixed Particle Zone on the Spiral Separation Process and Its Structural Optimization

Cross-sectional geometry is of significance in determining the flow characteristics and the particles separation in spiral concentrators. The effects of the cross-sectional geometry within the mixed particle zone on the secondary flow and the separation process of hematite and quartz particles with a size of 89.5 μm were investigated via a computational fluid dynamics (CFD) approach. The optimization of the line segment slopes was conducted using response surface methodology (RSM). The results indicate that the peak radial fluxes and average radial velocities of the secondary flow are positively correlated with the corresponding line segment slope. The independent adjustment of line slopes in regions Ⅰ and Ⅱ, and the interaction of line slopes in regions Ⅰ and Ⅲ, influence the separation efficiency of hematite and quartz particles significantly. The separation performance of the experimental spiral concentrator with a cross-sectional profile of the optimized line segments for a feed of hematite and quartz with a size range of -100+75 μm is remarkably improved by nearly 5%. This study provides insights for the cross-section design of spiral concentrators for the effective separation of coarse-grained hematite and quartz.

Impact of Process and Machine Parameters in the Charging Section on the Triboelectric Separation of Wheat Flour in a Vertical Separator

Triboelectric separation has recently been investigated as a novel process for dry enrichment and separation of protein of various crops like wheat flour. The triboelectric effect allows for the separation of starch and protein particles in an electric field based on their different charging behavior despite having a similar density and size distribution. Particles are triboelectrically charged in a charging section before being separated in an electric field based on their polarity. While the charging section is crucial, the influence of process parameters remains largely unexplored. Thus, the influence of the charging sections’ dimensions and the particle concentration as process key parameters was investigated experimentally. Varying the length (0, 105, and 210 mm) showed that the protein shift increases with the length (max. 0.53%) during separation. Varying the diameter (6, 8, and 10 mm) influenced the charging behavior, resulting in an increase in protein accumulation on the negative electrode as the diameter decreased. Varying the mass flow of flour (40, 80, 160, and 320 g·h−1) also affected the separability, leading to a maximum protein shift of 0.61%. Based on the observed results, it is hypothesized that the electrostatic agglomeration behavior of oppositely charged particles is directly affected by alterations in machine parameters. These agglomerates have a charge-to-mass ratio that is too low for separation in the electric field.

Transport and Plugging Performance Evaluation of a Novel Recrosslinkable Microgel Used for Conformance Control in Mature Oil Fields with Superpermeable Channels

Summary Although recrosslinkable preformed particle gel (RPPG) has been successfully evaluated in the literature for mitigating conformance problems in open-fracture applications, there are no studies that have examined the transportation and plugging performance of microsized RPPGs (micro-RPPG) in high-permeability channels. We systematically evaluated a novel micro-RPPG and its transportation mechanism in matrix-like media. The micro-RPPG can recrosslink to form a bulk gel after being placed in the reservoir, combining the advantages of both in situ and preformed particle gel (PPG) systems. This recrosslinking ability prevents the gel from being washed out easily, ensuring sustained performance under reservoir conditions. In this study, the micro-RPPG characterization, self-healing process, transportation behavior, and plugging performance were investigated. A sandpack model with multipressure taps was utilized to assess the micro-RPPG suspension’s transport behavior and plugging efficiency. In addition, micro-optical visualization of the gel particles was deployed to study the particle size changes before and after the swelling process. Bottle tests showed that micro-RPPG could be dispersed and remain as separate particles in water with a concentration below 8,000 ppm, which is a favorable concentration for particle gel pumping. However, during the flooding test, the amount of micro-RPPG can be entrapped in the sandpack, resulting in a higher microgel concentration (higher than 8,000 ppm), endowing the gel particles with recrosslinking ability even with excessive water. The micro-RPPG could propagate through the sandpack model, and the required pressure gradient mainly depends on the average particle/pore ratio and gel concentration. The gel suspension significantly reduced channel permeability, providing sufficient resistance to post-waterflooding (more than 99.97% permeability reduction). In addition, the evaluation of micro-RPPG retention revealed that it is primarily affected by both gel concentration particle/pore ratios. We have demonstrated that the novel recrosslinkable micro-RPPG can transport through large channels, and it can also provide effective plugging due to its unique recrosslinking property. However, by this property, the new microgel exhibits enhanced stability and demonstrates resistance to being flushed out in such high-permeability environments. Furthermore, with the help of novel technology, it is possible to overcome the inherited problems commonly associated with in-situ gel treatments, including chromatographic issues, low-quality control, and shearing degradation.

A method for measuring the critical pore diameter of a homogeneous microchannel separator based on image analysis and a simulation comparison of CFD-DEM

Fine particles being captured or escaping from particle beds (microchannel separator) is a widespread phenomenon, with the size and distribution of pores (microchannel) significantly affecting these phenomena. However, due to the complexity of the pore structure, accurately measuring and validating it poses challenges. This paper introduces a new method to calculate the critical pore diameter of homogeneous microchannel separators (three types of homogeneous separation media with particle sizes of 0.8 mm, 1.0 mm and 1.2 mm). Initially, particle bed units with a thickness twice the diameter of the separation media were captured from multiple orthogonal projection directions to obtain high-resolution images of the pore structure. Then, the Feret diameter distribution of the pores were analyzed to quantify pore size and distribution. Next, unresolved CFD-DEM method was used to simulate the capture of fine particles to optimize and supplement the results. The results show that the average Feret diameter of the pores differs by only 0.85 μm, 1.70 μm, and 2.46 μm from the simulation results, and it is noted that the critical pore diameter is approximately 0.153 times that of the separation media diameter, the numerical difference from the critical dimension ratio is only 0.0017. Additionally, when the diameter of the fine particles is 0.155 to 0.165 times the diameter of the separation media, the homogeneous microchannel separator exhibits the highest efficiency during the deep bed filtration process. The study also examines the separation of homogeneous fine particles at varying inlet liquid flow rates, which can offer theoretical guidance for analyzing the porosity of microchannel separators and the efficient removal of solid pollutants, thus contributing novel ideas to deep bed filtration research.

Experiment investigation and multiscale modeling of biomass oxidative fast pyrolysis in a fluidized bed reactor

Experiments were conducted in a fluidized bed reactor to study the oxidative fast pyrolysis of biomass. The pressure drops along the bed height were measured, and the yield and composition of gas, liquid, and solid products were analyzed at various O2 concentrations. It was found that with the increase in oxygen concentration, the yield of biogas increased, especially CO2 and CO, while yields of bio-oil and biochar decreased. Under oxidative conditions, the fraction of tar in bio-oil was significantly reduced. A multiscale model was developed in the open-source code MFiX by integrating the reactor model based on the coarse-grained DEM-CFD, the intraparticle model, and the biomass oxidative fast pyrolysis kinetics. The model was verified by comparison with experimental data. As the oxygen concentration increases, the mixing and separation of biomass particles decreases, the residence time increases, the axial distribution moves upward, and the Lacey mixing index decreases. This study established experimental and theoretical foundations for designing and scaling up oxidative fast pyrolysis of biomass in fluidized beds.

Viscoelastic particle focusing and separation in a microfluidic channel with a cruciform section.

Considerable attention has been given to elasto-inertial microfluidics, which are widely applied for the focusing, sorting, and separation of particles/cells. In this work, we propose a novel yet simple fabrication process for a microchannel with a cruciform section, where elasto-inertial particle focusing is explored in a viscoelastic fluid. SU-8 master molds for polydimethylsiloxane (PDMS) structures were fabricated via standard photolithography, and then plasma bonding, following self-alignment between two PDMS structures, was performed for the formation of a microchannel with a cruciform section. The particle behaviors inside the fabricated microchannel were experimentally investigated for various flow rates and particle sizes and compared with those inside a microchannel with a square cross section. The experimental results revealed that 3D particle focusing was achieved in the center under viscoelastic fluid flow over a wide range of flow rates without any shear thinning. Even for small particles (∼2 μm), single-line particle focusing was observed in the microchannel with a cruciform section but not in a square microchannel with the same hydraulic diameter (Dh = 75 μm). The effects of four reflex angles (270°) on particle focusing were quantitatively evaluated through numerical simulation. The simulation revealed that the migration pattern of particles is governed by the combined effect of the reflex angles and fluid inertia, leading to characteristic particle focusing behavior within the cross section of the cruciform microchannel. These findings agree well with the experimental results, which highlight the superior capability of the cruciform microchannel for inertial particle focusing across a wide range of particle sizes.

Application of some cationic pullulan and curdlan derivatives as flocculants in fungicides-containing wastewater purification

The ability of some cationic pullulan (TMAPx-P) and curdlan (TMAP0.4-C) derivative to remove different fungicide particles from synthetic wastewater has been studied. Commercial fungicides formulations of different type, Bordeaux mixture (BM), Dithan M45 (Dt) and Melody Compact49 WG (MC) have been used. The influence of some parameters related to the dispersion characteristics (suspension pH and salinity) and the polysaccharide derivatives (polymer dose, the ionic groups content, flexibility) on the separation process have been assessed. All the polysaccharide samples revealed a good removal efficiency (RE%) for the fungicide formulations prepared in saltless aqueous solutions, namely between 94 and 98 % for BM, 81.5–85 % for Dt, 88–91 % for MC. Slightly higher residual fungicides absorbance percent values for the suspensions prepared in the presence of salts (up to 7 %) than those prepared in water have been noticed. Less amount of BM and MC particles were removed in acidic pH than in water and basic pH, while contrary results were recorded in case of Dt ones, irrespective of the flocculant used. However, the RE% values were located between 79 % and 98 % over the entirely suspension pH investigated. Both zeta potential and floc size measurements indicated the charge patch flocculation mechanism for the fungicide particles separation.

Factors governing crusting formation in soils in Southern Mali, West Africa: Evaluation of susceptibility indices

In Southern Mali and neighboring semi-arid Sahel regions, soil crusting and sealing are common and significant phenomena for people who depend on agriculture for their livelihoods. These processes form hard, impermeable layers on the soil surface, reducing water infiltration, increasing runoff and erosion, and hindering germination, seedling emergence, and productivity. Factors such as rainfall intensity, topography, soil attributes, and poor management practices contribute to these phenomena. Here, we aimed to analyze soil attributes affecting crust formation and evaluate them using indicators like the structural stability index (StI), particle separability index (PSI), and crusting susceptibility index (CSI). Soils samples from agricultural and native areas in Southern Mali were analyzed for physical, chemical, mineralogical, and micromorphological attributes. Results revealed that the soils in these regions have high silt and fine sand content and low organic carbon content. Poor soil management, leading to prolonged periods of bare soils, significantly contributes to crusting. Kaolinitic clays, Ca2+ and Mg2+ contents did not appear to affect crusting. The PSI revealed a high risk of aggregate disruption in both agricultural and native lands, demonstrating soil vulnerability to degradation. The StI showed limited risk of structural degradation in native lands, while agricultural soils were more susceptible to crusting. The CSI indicated moderate crusting susceptibility across the regions. By examining the three indices related to texture attributes and organic carbon, this study provides insights into estimating susceptibility to crusting through the evaluation of the risk of soil structural degradation, particle separation, and overall soil susceptibility to surface crusting, all of which underscore the need for improved soil attributes. It emphasizes the importance of implementing effective soil management strategies, particularly the adoption of cover crops, to enhance organic carbon content and increase vegetation cover. These measures are essential for improving soil health and minimizing the risk of crusting.

Evaluating the capacity of magnetic ionic liquids for separation and concentration of non-enveloped viral particles and free viral genomic RNA.

Magnetic ionic liquids (MILs) have proven effective as capture reagents for foodborne bacterial pathogens; however, there are currently no published studies regarding their use with foodborne, non-enveloped viruses. In this study, a protocol was evaluated for capture and recovery of bacteriophage MS2, a human norovirus surrogate, and purified viral genomic single stranded RNA (ssRNA) from an aqueous suspension using MILs. Transition metal-based MILs showed similar capture and recovery efficiency for both targets. A rare earth metal-based MIL showed much greater capture efficiency than the transition metal-based MILs, but displayed similar recovery. All tested MILs showed slightly higher capture and recovery efficiency for free RNA in comparison to intact virus, though overall trends were similar, and most MILs could recover both targets at as little as 102 PFU/mL intact MS2 or copies/mL purified RNA. A plaque assay confirmed that contact with MILs did not significantly reduce viral infectivity. Adjusting MIL volume gave no significant changes in capture or recovery, likely due to interplay between volume for the hydrophobic MIL and dispersion. Reducing the elution volume gave a slight increase in recovery, indicating MILs could be used for target enrichment after further optimization. MILs could also capture MS2 from romaine lettuce rinsate at comparable or even higher levels than from pure suspension, though loss in recovery was observed when the rinsate was prepared in an alkaline elution buffer. Overall, these results demonstrate the potential utility of MILs as concentration reagents for foodborne viruses, particularly for in-field applications.

Permeability–selectivity trade-off for a universal leaky channel inspired by mobula filters

Mobula rays have evolved leaf-shaped filter structures to separate food particles from seawater, which function similarly to industrial cross-flow filters. Unlike cross-flow filtration, where permeability and selectivity are rationally designed following trade-off analyses, the driving forces underlying the evolution of mobula filter geometry have remained elusive. To bridge the principles of cross-flow and mobula filtration, we establish a universal framework for the permeability–selectivity trade-off in a leaky channel inspired by mobula filters, where permeability and selectivity are characterized by the pore-scale leaking rate and the cut-off particle size, respectively. Beyond the classic pore-flow regime in cross-flow filtration, we reveal transition and vortex regimes pertinent to mobula filtration. Combining theory, physical experiments, and simulations, we present distinct features of water permeability and particle selectivity across the three regimes. In particular, we identify an unreported 1/2-scaling law for the leaking rate in the vortex regime. We conclude by demonstrating that mobula filters strike an elegant balance between permeability and selectivity, which enables mobula rays to simultaneously satisfy biological requirements for breathing and filter feeding. By integrating cross-flow and mobula filtration into a universal framework, our findings provide fundamental insights into the physical constraints and evolutionary pressures associated with biological filtration geometries and lay the foundation for developing mobula-inspired filtration in industry.

Dual solutions of hybrid nanofluid flow past a permeable melting shrinking sheet with higher-order slips, shape factor and viscous dissipation effect

Purpose This paper aims to explore dual solutions for the flow of a hybrid nanofluid over a permeable melting stretching/shrinking sheet with nanoparticle shape factor, second-order velocity slip conditions and viscous dissipation. The hybrid nanofluid is formulated by dispersing alumina (Al2O3) and copper (Cu) nanoparticles into water (H2O). Design/methodology/approach The governing partial differential equations (PDEs) are first reduced to a system of ordinary differential equations (ODEs) using a mathematical method of similarity transformation technique. These ODEs are then numerically solved through MATLAB’s bvp4c solver. Findings Key parameters such as slip parameter, melting parameter, suction parameter, shrinking parameter and Eckert number are examined. The results reveal the existence of two distinct solutions (upper and lower branches) for the transformed ODEs when considering the shrinking parameter. Increasing value of Cu-volume fraction and the second-order velocity slip enhances boundary layer thicknesses, whereas the heat transfer rate diminishes with rising melting and suction parameters. These numerical results are illustrated through various figures and tables. Additionally, a stability analysis is performed and confirms the upper branch is stable and practical, while the lower branch is unstable. Practical implications The analysis of hybrid nanofluid flow over a shrinking surface has practical significance with applications in processes such as solar thermal management systems, automotive cooling systems, sedimentation, microelectronic cooling or centrifugal separation of particles. Both steady and unsteady hybrid nanofluid flows are relevant in these contexts. Originality/value While the study of hybrid nanofluid flow is well-documented, research focusing on the shrinking flow case with specific parameters in our study is still relatively scarce. This paper contributes to obtaining dual solutions specifically for the shrinking case, which has been less frequently addressed.

Precision Macroporous Monoliths Made Using High‐Throughput Microfluidic Emulsification

Materials with pore sizes ranging from micrometers to millimeters find use in thermal insulation, acoustics, separation, and energy‐related applications. While several routes have been developed to manufacture such macroporous materials, current fabrication technologies remain limited in either scalability or pore size control. Herein, a scalable microfluidic approach is reported to create macroporous materials with precisely controlled pore sizes from monodisperse emulsion templates. Emulsion droplets produced in a parallelized step emulsification device are assembled by gravity and converted into macroporous monoliths by polymerization and drying. Microstructural analysis and model filtration experiments show that the pore windows of the bulk macroporous material can be tightly controlled and used for the size‐selective separation of particles from suspensions. By heat treating macroporous structures of selected compositions, one can also create bulk carbon and silica glass monoliths with unique cellular architectures for potential applications as filters, separation membranes, or catalyst supports.

SELECTION OF TOOLS AND MACHINING PARAMETERS FOR PIPE WALLS

This review paper examines the techniques and factors involved in pipe wall processing, with a focus on the essential technologies utilized in this field. The study revealed crucial elements, such as ASTM A350-LF2 Class 1 carbon steel, renowned for its exceptional mechanical qualities and ability to withstand low temperatures. An exhaustive analysis has been conducted on the chemical makeup of this steel to comprehend its capacity to adjust and endure in various operational environments. The study focused on examining several particle separation processes, including as turning, milling, drilling, and grinding, in order to determine the exact equipment and criteria needed for each technique. The cooling and lubricating process received particular emphasis, with thorough investigation of several agents, including CASTROL HYSOL T15, and their impact on surface quality and tool longevity. The utilization of these compounds has been discovered to substantially decrease tool temperature and enhance machining quality. Upon closer examination of the processing techniques specified in section A-A of the tube wall, it was determined that advanced procedures such as floating plug drawing and micro-sized spiral tube hydroforming were discovered. These techniques allow the attainment of superior surface quality and precise dimensions, which are crucial for guaranteeing the structural integrity of the pipe. Cutting tools, processing equipment, and coolants and lubricants are essential components in the manufacturing of pipe walls. Nanoparticulate cooling and lubrication systems, which are advanced technologies, have demonstrated their effectiveness in minimizing friction and heat during machining. As a result, these systems enhance productivity and prolong the lifespan of tools. According to the article, the essential components for attaining high-quality manufacture of pipe walls are cutting tools, processing equipment, and coolants and lubricants. Additional study is advised to enhance processing parameters, create eco-friendly coolants and lubricants, and utilize artificial intelligence for predictive modeling and optimization of processing. This establishes the groundwork for future research and innovation in the pipe wall production business, with the objective of attaining enhanced efficiency and sustainability in production processes.

Numerical Implementation of Electrostatic Solver Within OpenFOAM for Gas Turbine Intake Filtration

Abstract Gas turbines require filtered air to preserve operability, availability, and efficiency. Fouling, corrosion, and erosion severely affect the performance of the axial compressor and it can be in part prevented by filtering the air intake. For this reason, several stages of filters can be used in series to catch pollutant particles gradually smaller and with a high level of capturing efficiency. Traditionally, the separation is obtained using cartridges of porous material, which provide a high level of filtration but at the same time generate a pressure drop increasing over time. Another common type of filter is the inertial one, whose operating principle is based on the inertial force acting on the solid particles to separate them from the mainstream. The capturing efficiency of the inertial filter is not comparable with the porous one and for this reason, it is used upstream as a pre-filter. In recent years, another technique has been developed to filter air flows thanks to an electrostatic field, that is induced inside the flow. The electrostatic force generated is able to attract and separate metallic particles. In the present work, numerical investigations are carried out to simulate the effect of the electrostatic force for gas turbine filtering systems. The computational fluid dynamics tool used is openfoam, whose official release can simulate inertial and porous filtering media, while for electrostatic one is not possible due to the absence of a library able to simulate the electrostatic force that acts on the discrete phase. A new library was developed in order to calculate the electric field, the electric potential, and the charge density of the continuous phase. Simulation results show how the calculation of these quantities allows us to predict the electrostatic force acting on particle flows in the presence of electrostatic fields.

Comparative Analyses of Dynamic Characteristics of Gas Phase Flow Field Within Different Structural Cyclone Separators

The gas phase flow field inside a cyclone separator is crucial to the particle separation process. Previous studies have paid attention to the steady-state characteristics of the gas phase flow field, while research on its dynamic characteristics remains insufficient. Meanwhile, cyclone separators often adopt different structural forms according to the process requirements, the evolution laws of the dynamic characteristics flow field within them are still not well understood. Therefore, in this study, a hot-wire anemometer (HWA) was employed to measure the instantaneous tangential velocity of the gas phase flow fields within different structural cyclone separators (cylinder type, cylinder–cone (no hopper), and cylinder–cone (with hopper)). Comparative analyses and discussions were conducted regarding the dynamic characteristic distribution rules of the flow field in the time domain and the frequency domain. The results revealed that the dimensionless tangential velocity distributions of different types of cyclone separators all conformed to the Rankine vortex structure. The instantaneous tangential velocity fluctuated with low frequency and high amplitude, and the low-frequency velocity fluctuation exhibited a transfer behavior along the radial direction. Compared with the cylinder–cone-type cyclone separator, the tangential velocity in the cylinder-type cyclone separator fluctuated more greatly, and its quasi-periodic behavior was also more obvious. The time-averaged tangential velocity, the tangential velocity fluctuation intensity (Sd), and the dominant fluctuation frequency all had obvious attenuation along the axial direction in the cylinder-type cyclone separator, while the above-mentioned parameters had no attenuation along the axial direction in cylinder–cone-type cyclone separators. Additionally, the backflow from the hopper of the cylinder–cone-type cyclone separator (with hopper) led to an increase in the instantaneous tangential velocity fluctuation intensity of the local flow field near the dust outlet, as well as the occurrence of the “double dominant frequencies” phenomenon.

Ultra-Stretchable Microfluidic Devices for Optimizing Particle Manipulation in Viscoelastic Fluids.

Viscoelastic microfluidics leverages the unique properties of non-Newtonian fluids to manipulate and separate micro- or submicron particles. Channel geometry and dimension are crucial for device performance. Traditional rigid microfluidic devices require numerous iterations of fabrication and testing to optimize these parameters, which is time-consuming and costly. In this work, we developed a flexible microfluidic device using ultra-stretchable and biocompatible Flexdym material to overcome this issue. Our device allows for simultaneous modification of channel dimensions by external stretching. We fabricated a stretchable device with an initial square microchannel (30 μm × 30 μm), and the channel aspect ratio can be adjusted from 1 to 5 by external stretching. Next, the effects of aspect ratio, particle size, flow rate, and poly(ethylene oxide) (PEO) concentration that make the fluid viscoelastic on particle migration were investigated. Finally, we demonstrated the feasibility of our approach by testing channels with an aspect ratio of 3 for the separation of both particles and cells.

Optimization analysis of the particle focusing and separation parameters of a sheathless microfluidic device using standing surface acoustic waves

Flow-based particle separation usually requires a sheath flow for particle manipulation. Sheath fluid is a specialized buffer solution that directs the alignment of particles or cells into the center of the stream. By utilizing sheath flow, the particles or cells can be focused on the middle line of the microchannel, where they can be individually analyzed. However, the method requires an additional design for creating a suitable sheath flow. Purity and separation efficiency may also be influenced by the sheath flow. In this study, we present a sheathless device for particle focusing and separation using standing surface acoustic waves (SSAWs). The device comprises two regions: the focusing and separation regions. In the focusing region, particles in a continuous flow are aligned in the middle of the microchannel by SSAWs; in the separation region, tilted-angle SSAW-based particle separation is used to control particle migration. Varying particle sizes were focused in the focusing region and then separated in the separation region in the sheathless device. Experiments and simulations were also utilized to optimize a sheathless device. 10 and 20 μm particle focusing and separation were conducted in a sheathless device for the first time. We demonstrate that the separation of particles with a diameter of 10 and 20 μm has 90.8 ± 1.75% and 99.5 ± 0.8% separation efficiency, and 98 ± 3.4 and 97.9 ± 0.9% purity. Compared with other focusing and separation technologies, our device can also provide high purity, high separation efficiency, and high device density.

CFD analysis of microscopic particle separation in low-volumetric classifiers: DPM tracking and experimental validation for enhanced efficiency using geometric modification strategy

The increasing demand for advanced air quality management technologies highlights the need for efficient separators capable of classifying microparticles by size. This study introduces a novel approach of geometric modifications to optimize low-volumetric environmental separators through Computational Fluid Dynamics (CFD) simulations. This study investigated micron particle flow behaviour, vortex strength, and separation chamber design using Lagrangian particle tracking to capture the complex particle–fluid interactions. Key geometry modifications included optimizing internal configurations, such as tube arrangements and discharge tube lengths, which resulted in significantly improved separation efficiency. The CFD simulations were validated against experimental data with flow rates ranging from 10 to 20 LPM (Re = 1008, 1512, 2016), demonstrating flow patterns, vorticity, and particle retention. A major contribution of this study is the particle retention efficiency analysis across a wide range of particle sizes. Particles larger than 10 µm were captured with near-perfect efficiency, while capturing finer particles (1–8 µm) proved more challenging, highlighting areas for future improvement. Notably, increasing the number of separation tubes from 3 to 4 and adjusting their heights led to a 10 % increase in particle retention for particle diameters of 10 and 20 µm. Additionally, higher flow rates, especially at 17 LPM (Re = 1714), increased capture rates for medium-sized particles by prolonging residence times through increased turbulence. This research advances micron particle separation technologies through design optimizations, supported by experimental and numerical analysis. The findings have broad implications for improving the performance of environmental separators in industrial applications, and for future developments in air quality management systems.

Design and testing of an innovative electro-dynamic filter for gas turbine intake systems

Abstract Gas turbines require filtered air to preserve the efficiency and the life of the system. Different degradation processes can occur depending on the size and composition of the contaminants. The compressor’s performance can be negatively impacted by fouling and erosion, which alter the shape and roughness of the blades. To limit the effects of the aforementioned phenomena, multistage filtration systems are commonly installed to reduce the contamination at the gas turbine inlet. Traditionally, particle separation is performed through mechanical filtration, which means that the particles are trapped inside cartridges of porous materials. This typology of filter guarantees a high filtration efficiency but on the other hand, generates remarkable pressure drop increasing over time. Inertial filters instead separate contaminants from the flow by utilizing the effect of inertial force acting on solid particles. In recent years, electrostatic filters have become widespread. The fibers of the filters are charged with an electrostatic field before installation and this charge is capable of separating and attracting metallic particles from the airflow. However, the electrostatic field’s effect diminishes with the exposure time with this type of filter. This work presents an innovative electro-dynamic filtration system for gas turbine application. The geometry and electrical features of the devices are designed to keep low-pressure drop and high capturing efficiency over time. To achieve these goals, a numerical campaign is performed using an in-house OpenFOAM solver, which takes into account the effect of the electrostatic force of the Lagrangian phase. After the definition of the optimal geometry, experimental tests are performed to validate the numerical results. Finally, a comprehensive laboratory-scale campaign is carried out to evaluate filtration efficiency under various environmental conditions, including different types of contaminants, concentrations, and exposure times.