Particle Flow Rate Research Articles

Design and evaluation of a dilute flow particle-to-air heat exchanger for energy storage applications

The use of inert and redox-active particles for high-temperature energy storage requires the development of components that can efficiently transfer energy to high-pressure working fluids like supercritical carbon dioxide (sCO2). Dilute flow reactors can enable high working fluid outlet temperatures and minimal parasitic losses compared to moving packed bed and fluidized bed reactors. This research uses both computational and experimental methods to explore the design trade-offs and practical challenges of a novel component for transferring energy from dilute flows of hot, reduced metal oxide (MOx) particles to sCO2 in tubes. A discretized thermal resistance network model, which accounts for particle hydrodynamics, multi-mode heat transfer, and reaction equilibrium, guides the design of a prototype device. This device is experimentally tested with a surrogate heat transfer fluids and inert particle temperatures up to 400 °C and a heat duty exceeding 1 kW. The data are used to validate the thermal hydraulic sub-models, allowing for the simulation of reacting particle scenarios. Under nominal design conditions, the flow rate of reactive particles is predicted to be 30 % lower than that of inert particles for the same energy recovered, with over 70 % of the stored particle energy transferred to the sCO2. These findings can inform the design of more efficient energy recovery reactors for particle-based systems and can be integrated into system-level concentrated solar power models with thermal storage to optimize operating conditions.

Finite Element Simulation of Aerosol Particle Trajectories in a Cantilever-Enhanced Photoacoustic Spectrometer for Characterization of Inertial Deposition Loss

The cantilever-enhanced photoacoustic spectrometer is a sensitive instrument developed originally for trace gas measurements and has lately been successfully applied for measuring light-absorbing particles, such as aerosols. The finite inertia of aerosol particles can cause the particles to be deposited on the walls in the spectrometer’s flow channels, which creates a source of uncertainty for the measurement process. In this study, we characterized this inertial deposition in the spectrometer using finite element-based modeling. First, computational fluid dynamics was used to calculate the distribution of airflow within a 3D model of the spectrometer’s flow channels. Then, the trajectories of aerosol particles were computed to evaluate the inertial deposition losses. The modeling method was validated by computing inertial deposition for two known cases of laminar flow, namely particles flowing through a pipe with a 90-degree bend and a pipe with an abrupt contraction. The particle transmission of the photoacoustic spectrometer was experimentally measured. Differences and similarities between measured and modeled results are discussed. The modeled inertial deposition losses ranged from approximately 5% to 70% for particle diameters between 50 and 500 nm. This modeling approach provides valuable insight into the influence of particle size and flow rate on the inertial deposition and also pinpoints the physical location of the loss within the spectrometer, which is valuable for improving the measurement process.

Solid-electrolyte-inspired totally asymmetric simple exclusion process with parallel channels and random defects

We propose a simplified probabilistic model to investigate the fundamental physics of particle transport in parallel channels having bypasses and defects, mimicking the distinctive pathways found in a class of solid-electrolyte materials. Our results reveal that increases in the bypass interval and the number of defects induce significant macroscopic density fluctuations, substantially reducing overall flow rates. Notably, we find that the particle flow rate decreases exponentially with the product of bypass interval and defect probability. The decay exponent was dependent on the particle density, which reflects the nonlinear effects of particle congestion. Our findings may suggest that the presence of more bypass sites and fewer defects in the pathways has a significant impact on the performance of electrolyte materials. Published by the American Physical Society 2024

Optimizing Railway Tribology: A Systematic Review and Predictive Modeling of Twin-Disc Testing Parameters

Twin-disc testing is crucial for understanding wheel–rail interactions in railway systems, but the vast array of testing parameters and conditions makes data interpretation challenging. This review presents a comprehensive analysis of the twin-disc literature experimental data, focusing on how various parameters influence friction and wear characteristics under stationary contaminant conditions. We systematically collected and analyzed data from numerous studies, considering factors such as contact pressure, speed, material hardness, sliding speeds, adhesion, and a range of contaminants. This research showed inconsistent data reporting across different studies and statistical analyses revealed significant correlations between testing parameters and wear rates. For sand-contaminated tests, a correlation between particle size and flow rate was also highlighted. Based on these findings, we developed a simple predictive model for forecasting wear rates under varying conditions. This model achieved an adjusted R2 of 0.650, demonstrating its potential for optimizing railway component design and maintenance strategies. Our study provides a valuable resource for researchers and practitioners in railway engineering, offering insights into the complex tribological interactions in wheel–rail systems and a tool for predicting wear behavior.

Analysis and mitigation of erosion wear of transfer ducts in a falling particle CSP system

Solid particles are effective heat capture and transfer media for next-generation (Gen3) concentrating solar power (CSP) plants that offer high-temperature operability, lower levelized cost, and higher efficiency. However, the relative motion of the solid particles with respect to the CSP system components causes significant wear of the wall materials in the form of erosion and abrasion. The transfer duct is one of the prevalent components in the falling particle CSP system that experiences erosion wear due to the impact of particles on its surface, which depends on several factors, such as duct design, material, and particle flow rate, among others. In this work, erosion wear in the transfer duct and its mitigation were studied computationally through different duct designs and particle flow parameters, including transfer duct length, diameter, slanted angle of the duct, and entrance velocity. Computational simulations based on particle tracking and discrete element modeling were used to understand erosion behavior systematically and, in turn, identify areas most prone to erosive wear. It was found that the use of erosion-resistant coatings in selected locations determined from the simulations was sufficient to mitigate overall erosion wear in the component. This study provides fundamental insight into the erosion wear of a key component of the falling particle CSP system for the first time and the design approaches to mitigate wear.

Numerical Investigation of Erosion in Pipeline Bends Using CFD Simulation

Erosion in pipeline bends is a significant issue in various industrial applications, particularly in oil and gas transportation systems. This study presents a numerical investigation of erosion in pipeline bends using Computational Fluid Dynamics (CFD) simulation. The primary focus is to predict erosion rates and identify erosion-prone areas based on different flow conditions, particle properties, and bend geometries. A multiphase flow model incorporating Eulerian-Lagrangian approaches was used to simulate the interaction between fluid and solid particles. The erosion rates were evaluated using empirical models that relate particle impact characteristics, such as velocity and angle of impingement, to material degradation. Simulations were conducted for various particle sizes, velocities, and flow rates, allowing for a comprehensive analysis of erosion patterns. Results indicate that erosion is concentrated on the outer walls of the bend, with higher particle velocities exacerbating material wear. Additionally, increasing particle size and flow velocity significantly influence the erosion rates. The findings of this study provide valuable insights into optimizing pipeline design and flow conditions to mitigate erosion, thereby extending the lifespan of pipeline systems in industrial applications.

Microfluidic device with three-dimensional microtip electrodes for efficient capture and concentration of bacteria-sized microparticles using dielectrophoresis

Microfluidics-based systems have gained considerable attention in the lab-on-chip field owing to their ability to separate, concentrate, and analyze microparticles. Concentrating microparticles is crucial for the high-sensitivity measurement of biomarkers in the analysis of cells or bacteria. This study presents a microfluidic chip using dielectrophoresis (DEP) to capture bacterial microparticles. The chip features a vertically arranged microtip electrode and an indium tin oxide (ITO) electrode, enhancing the electric field concentration effect and enabling optical analysis of the collected particles. The device was designed and fabricated using microfabrication techniques that incorporate a patterned array of microtip electrodes on a polydimethylsiloxane (PDMS) substrate. Experimental studies and numerical simulations were conducted to evaluate the device performance. The fabricated device was applied to the concentration of fluorescent beads with various variables such as particle size, frequency, voltage, and flow rate. The experimental results demonstrated the successful trapping and concentration of microparticles using DEP forces. The recovery rates of the 2.29 µm and 4.42 µm PS beads, when introduced at a flow rate of 1 μL/min and subjected to an applied alternating current (AC) voltage of 200 kHz and 10 Vpp at the microtip electrode, were measured to be 85.50±2.69 % and 91.83±0.63 %, respectively. Additionally, to assess the applicability of the microtip electrode-based DEP device proposed here for bacteria concentration, capture experiments were conducted using Escherichia coli, demonstrating a recovery rate performance of 77.93±7.31 %. These findings highlight the potential of the proposed microfluidic chip for the concentration and measurement of bacteria, such as E. coli.

Non-steady flow decomposition behaviors of heat and mass transfer on intrinsic kinetics for methane hydrate particles transported in pipelines

The differential equations governing the decomposition rate and activation energy, convective mass transfer, methane diffusion and fugacity, as well as heat conduction and enthalpy change were derived by integrating thermal convection, heat conduction, mass transfer and intrinsic kinetics. Mathematical models for decomposition kinetics and thermodynamics in a non-steady field were solved using a radial logarithmic grid for node division and discretization of the equations. The study elucidated the heat and mass transfer processes as well as decomposition kinetics in pipelines by analyzing the impacts of particle size, temperature, pressure, flow rate and activation energy on decomposition rate. The results indicated that compared with the isothermal decomposition of the intrinsic kinetic model and static experimental decomposition, the complex non-steady multiphase flow model offers a more accurately simulation of hydrate decomposition as well as associated heat and mass transfer processes. Hydrate decomposition is characterized as a non-isothermal dynamic ablation process with heat transfer rate and intrinsic kinetics dominating during the preliminary stage and the stable stage, respectively. An increasing in the slurry temperature, temperature fluctuation and flow rate accelerated the heat transfer rate capacity, enhanced convective heat transfer capacity and facilitated hydrate decomposition, with the mass transfer rate exhibiting lesser influence. The particle surface area and slurry temperature exhibited the most significant influence on hydrate decomposition, which was followed by flow rate. Upon increasing particle size from 1 mm to 5 mm and the temperature from 293 K to 313 K, the decomposition rate increased by 20.7 times and 13.5 times, respectively. Furthermore, enhancing temperature and flow rate while decreasing particle size and pressure decreased both the decomposition time and the duration required for the decomposition rate to reach its peak. Additionally, the decomposition rate and its constant vary with the activation energy.

Optimization and analysis of the inflow distribution influence on the middle discharge blow tank pneumatic conveying characteristics

The influence of different inflow gas distribution modes on the pneumatic conveying characteristics of the middle discharge blow tank was studied using an in-house pneumatic conveying experimental setup. The flow rates of pressurized gas, supplementary gas, and fluidized gas were varied in this study. The gas distribution mode was then optimized to improve the energy efficiency of the blow tank of a pneumatic conveying system. The results show that the particle mass flow rate, the solid-to-gas ratio, and the pressure drop increase first and then decrease with the pressurized gas and fluidized gas valves opening. In the case of supplementary gas, the particle mass flow rate and solid-to-gas ratio increase first and then decrease. However, an opposite trend is observed for the pressure drop, which decreases first and then increases. The results highlighted that the optimized gas distribution mode increases the mass flow rate of particles and the solid-to-gas ratio by 28.48% and 15.15%, respectively. The pressure drop of the blow tank has also increased slightly, by 0.88%. Therefore, the delivery capacity and efficiency of the middle discharge blow tank are greatly improved at the cost of a slight increase in energy consumption.

Numerical simulation of non-stationary regime of a submerged combustion setup operation

Relevance. The need to evaporate large quantities of brines at potash industry enterprises. Evaporation of brines in surface evaporators is difficult due to the encrustation of heat exchange surfaces by salt deposits. Therefore, such evaporation is most expedient to be carried out in submerged combustion apparatuses, since they do not contain heat-transmitting surfaces. However, in this type of apparatus, malfunctions may occur due to uncontrolled solid phase deposition. At the moment, the dynamics of the solid phase in submerged combustion devices is poorly studied. This study is part of a scientific program aimed at a comprehensive review of the laws of motion of solid particles in submerged combustion apparatuses. Aim. To study the hydrodynamic processes in the submerged combustion setup in the time interval corresponding to the beginning of its operation; describe the patterns of solid phase motion as a function of time. Object. Laboratory setup of submerged combustion. A simplified model of the thermal mode of operation without the subsequent transition of the liquid phase to steam is analyzed. Methods. The study was conducted by numerical experiment. The hybrid finite volume method was used in simulation in combination with the technology of the finite element method. The multiphase system was considered as two coexisting subsystems: gas–liquid and liquid–solid. Results. The paper considers the final time interval of the setup operation. It is found that during the time under consideration, a stationary mode of solid particle deposition is achieved. The authors have detected liquid flow velocity oscillations, leading to fluctuations in the mass flow rate of solid particles at the bottom of the setup. It was found that the velocity at the tip of the flue gas jet escaping from the burner nozzle, as well as the pressure at the nozzle section, have a similar form of oscillation. The authors substantiated the hypothesis about the determining influence of the instability of the jet movement of flue gases on the oscillatory behavior of the entire hydrodynamic system.

Nozzle Wear in Abrasive Water Jet Based on Numerical Simulation.

Particle diameters and jet pressure in abrasive water jet (AWJ) are significant jet properties which deserve a better understanding for improving AWJ machining performance. Some influence factors have been verified regarding nozzle wear in abrasive water jet polishing application. A three-dimensional model of a nozzle is established to analyze the influence of internal multi-phase flow field distribution, which is based on Euler-Lagrange methodology. With the increase of jet pressure, the erosion rate decreases; with the increase of the diameter and mass flow rate of the erosion particles, the erosion speed increases as well. When the diameter of the outlet is worn to 1.6 mm, the pressure on the work piece caused by the abrasive water jet increases by more than double compared to the non-worn nozzle; when the diameter of the nozzle outlet is worn to 1.6 mm, the shear force is 2.5 times higher than the shear force when the diameter is 1.0, which means that the jet force is divergent when the diameter is 1.6 mm, and the damage of the work piece is very serious. The obtained results could improve polishing efficiency on the work piece, extend nozzle lifetimes, and guide the future design of AWJ nozzles.

Clogging transition of granular flow in porous structures

The clogging transition of granular flow through a disordered porous structure is investigated by three-dimensional discrete element simulations. Results reveal the existence of an intermittent flow state, which has been already observed for active particles or agitated grains, but is absent in single-pore flows of passive particles. Interestingly, the analysis of the intermittent dynamics shows similar attributes to the bottleneck flow of active grains, i.e., exponential distribution of flowing intervals and power-law tails for the clogging times. Precisely, based on the exponent of the power-law tail, a clogging phase diagram for porous structures is proposed in the plane of the scaled pore size D/dp and the friction coefficient μs. Then, we demonstrate that the intermittency arises from a delay in the dissipation of particles' kinetic energy after clogging imposed by the porous structure. Finally, the maximum achievable particle flow rate driven by gravity is predicted from the Froude number Frm, which linearly scales with the pore size and the friction coefficient. Published by the American Physical Society 2024

Erosion Characterization Of Gas-Solid Jets Impinging Onto Inclined Surfaces

Erosion caused by solid particles is an important phenomenon in many industrial applications. Wear modelling is a complex phenomenon due to the many relevant variables. In any event, the dynamics of the fluid flow and particles need to be characterized so that their interrelations are well understood and models can be advanced. Depending on their sizes, particles immersed in solid-gas flows may deviate from the fluid stream, meaning that any deployed measuring technique must take this into account. The work describes through PIV and PTV the flow and particle dynamics of a round air-jet loaded with carbon silicate particles (SiO2) impinging onto an inclined surface. Flow conditions are set for two different Reynolds numbers and four impinging angles. The experimental results are compared with numerical simulations furnished by a two-way coupling scheme. The results show that erosion wear is highly dependent on the kinetic energy of the particle at impact. The larger the size of the particle or the larger its velocity, the larger is the damage it causes. A correlation between the thickness of removed material with particle size distribution and flow rate is presented. For low flow rates, the distinction between the damage caused by particles of various sizes is small.

Effect of variable conditions on transient flow in a solid–liquid two-phase centrifugal pump

To investigate the influence of altering operational parameters on the transient flow characteristics within the flow channel of a solid–liquid two-phase centrifugal pump, this study employs a particle model based on the Euler–Euler method. Utilizing the standard k–e model, flow field simulations are conducted using the ANSYS-CFX software. Specifically, the study focuses on throttle regulation scenarios, monitoring and comparing the external and internal flow parameters of the solid–liquid two-phase pump with those of a clear water medium centrifugal pump. The results indicate notable modifications in head, efficiency, and shaft power due to the presence of solid particles in the two-phase flow. Decreasing flow rates during throttle regulation lead to fluctuations in pressure and turbulence energy distribution. Furthermore, under identical operational conditions, the variable working conditions of the solid–liquid pump result in increased flow rates of solid-phase particles near the impeller's outer edge, with particles shifting toward the middle and tail of the vane suction surface. This phenomenon exacerbates wear on the vane tail of the suction surface. Moreover, the study identifies that changing operational conditions in the solid–liquid dual-flow centrifugal pump contribute to increased axial forces, consequently leading to pump vibrations. Overall, this research elucidates the transient flow characteristics within the flow channel of solid–liquid two-phase centrifugal pumps under varied operational conditions, serving as a foundational reference for assessing the stability of such pumps.

The bimolecular reactive transport in heterogeneous porous media: Sub-diffusion in interpretation of laboratory experiment

This present work consists of investigating the effects of particle size heterogeneity and flow rates on transport-reaction kinetics of CuSO4 and Na2EDTA2− in porous media, via the combination of a bimolecular reaction experiment and model simulations. In the early stages of transport, a peak is observed in the concentration breakthrough curve of the reactant CuSO4, related to the delayed mixing and reaction of the reactants. The numerical results show that an increase in flow rate promotes the mixing processes between the reactants, resulting in a larger peak concentration and a slighter tail of breakthrough curves, while an increase in medium heterogeneity leads to a more significant heavy tail. The apparent anomalous diffusion and heavy-tailing behavior can be effectively quantified by a novel truncated fractional derivative bimolecular reaction model. The truncated fractional-order model, taking into account the incomplete mixing, offers a satisfactory reproduction of the experimental data.

Effective adsorption of phosphate using a Mg–Al–La composite from synthetic/real wastewater: adsorptive behaviour, column tests and economic evaluation

ABSTRACT The present study utilised an adsorbent that integrates Mg with Al and La (i.e. MAL composite) to remove low-concentration phosphate from wastewater. The adsorption properties of MAL were identified through batch experiments of phosphate removal, in which the impacts of influencing factors such as initial pH and reaction time on the phosphate adsorption by MAL adsorbent were explored. Besides, the thermodynamics and kinetics were also investigated, where the phosphate adsorption follows the pseudo-second-order kinetics, indicating that chemisorption and internal diffusion control dominate the phosphate removal. Dynamic phosphate removal by MAL adsorbent was investigated using a fixed-bed column at different adsorbent particle sizes, flow rates and temperatures, in which the breakthrough curves were simulated. The phosphate removal by MAL adsorbent was examined at practical wastewater treatment, which achieves high efficiency and thus provides a preliminary basis for the commercial use of the adsorbent. Apart from this, the techno-economic analysis of phosphate adsorption was also conducted.

Polystyrene composite system: An alternative for wastewater treatment.

Rapid population growth intensifies water scarcity, highlighting the importance of treatment technologies such as reverse osmosis and membrane filtration to ensure safe drinking water and preserve resources. The use of polystyrene as a filter for polluted water is valuable due to its porous surface, efficiently retaining impurities. The system, a tubular reactor with a mixed polystyrene bed, underwent evaluations with varying particle sizes, flow rates and times, operating in dead-end mode and series system without recirculation with theoretical residence times between 180 and 360 min. The study, divided into two phases, optimized the system in the first phase, characterizing the filter bed and carrying out maintenance for 360 min at 0.5 L/min. Phase two evaluated the performance of the reactor in treating wastewater with flow rates of 0.5 and 1 L/min for 180 min. Under the best conditions of Phase I, 55% of Escherichia coli and turbidity were deactivated, not meeting potability standards. In Phase II, there was efficiency in the removal of several parameters, such as chemical oxygen demand (78.26%), total phosphorus (75%), nitrate (73.42%), ammonia (73.13%), nitrite (69.33%), potassium (70.83%), and sodium (68.75%). In addition, 98.32% of E. coli was deactivated, meeting CONAMA Class 2 and 3 irrigation standards.

Research on Erosion Mechanism and Protection Technology of Sand Bearing Fluid Pipeline

The purpose of this study is to explore the influencing factors of sand bearing fluid on pipeline erosion and evaluate the effects of different protection technologies. Through the construction of erosion testing equipment, the influence of sand particle size, concentration and flow rate on the erosion rate was systematically studied. The results show that the increase of sand particle size and concentration and the increase of flow rate will significantly increase the erosion rate. In addition, coating protection technology and alloying technology have been proved to be effective in reducing the erosion rate, and coating protection technology shows better protection effect. It provides theoretical basis and data support for pipeline design and protection in sand bearing fluid environment.

Modelling Drug Delivery to the Small Airways: Optimization Using Response Surface Methodology

AimThe aim of this in silico study was to investigate the effect of particle size, flow rate, and tidal volume on drug targeting to small airways in patients with mild COPD.MethodDesign of Experiments (DoE) was used with an in silico whole lung particle deposition model for bolus administration to investigate whether controlling inhalation can improve drug delivery to the small conducting airways. The range of particle aerodynamic diameters studied was 0.4 – 10 µm for flow rates between 100 – 2000 mL/s (i.e., low to very high), and tidal volumes between 40 – 1500 mL.ResultsThe model accurately predicted the relationship between independent variables and lung deposition, as confirmed by comparison with published experimental data. It was found that large particles (~ 5 µm) require very low flow rate (~ 100 mL/s) and very small tidal volume (~ 110 mL) to target small conducting airways, whereas fine particles (~ 2 µm) achieve drug targeting in the region at a relatively higher flow rate (~ 500 mL/s) and similar tidal volume (~ 110 mL).ConclusionThe simulation results indicated that controlling tidal volume and flow rate can achieve targeted delivery to the small airways (i.e., > 50% of emitted dose was predicted to deposit in the small airways), and the optimal parameters depend on the particle size. It is hoped that this finding could provide a means of improving drug targeting to the small conducting airways and improve prognosis in COPD management.

Linking Enceladus’ plume characteristics to the crevasse properties

Supersonic plumes of water vapour and icy particles have been observed by the Cassini spacecraft during several flybys over Enceladus. These plumes originate from the Tiger Stripes located in the South Polar Terrain (SPT), and indicate the presence of a subsurface ocean under the icy crust which is salty and contains complex organic molecules. Other characteristics of the plumes, such as the vent temperature, mass flow rate, velocity and mass fraction of icy particles can be used to determine the conditions in the channel, linking the subsurface ocean to the icy surface. In this paper, we developed a fluid dynamics model that accounts for nucleation, particle growth, wall accretion and sublimation. The channel behaves similarly to a converging–diverging nozzle, which forms supersonic plumes due to a pressure difference between the reservoir where the subsurface ocean is located and the exosphere. The geometry of the channel and its evolution with accretion of gas and sublimation of ice are studied to reproduce the characteristics of the plumes observed by Cassini. We first performed a parameter study on the channel geometry to determine how it influences the plumes’ velocity, solid fraction and exit temperature. Our results show that the size of the icy particles is primarily dependent on the length of the channel, indicating that large particles (∼75μm) must originate from within a kilometer below the surface, while smaller particles (∼3μm) can originate from only hundreds of meters below the surface. We further show that the velocity of the flow, exit temperature and nucleation depend directly on the exit-to-throat size ratio. We find that the channel geometry evolves within a few tens of hours until an equilibrium is reached, when considering the accretion of gas to the walls, or sublimation of ice from the walls. As the channel closes due to accretion, the flow becomes thinner, which in turn reduces accretion. After around 70 h, the accretion is sufficiently slowed such that the geometry does not evolve anymore. This equilibrium geometry produces higher Mach numbers and a larger particle size and solid fraction compared to the initial geometry.