Different Sizes Of Glass Beads Research Articles

Raman Spectroscopy of Disperse Systems with Varying Particle Sizes and Correction of Signal Losses.

In this paper, a dispersion of glass beads of different sizes in an ammonium nitrate solution is investigated with the aid of Raman spectroscopy. The signal losses caused by the dispersion are quantified by an additional scattered light measurement and used to correct the measured ammonium nitrate concentration. Each individual glass bead represents an interface at which the excitation laser is deflected from its direction causing distortion in the received Raman signal. It is shown that the scattering losses measured with the scattered light probe correlate with the loss of the Raman signal, which means that the data obtained can be used to correct the measured values. The resulting correction function considers different particle sizes in the range of 2-99 µm as well as ammonium nitrate concentrations of 0-20 wt% and delivers an RMSEP of 1.952 wt%. This correction provides easier process access to dispersions that were previously difficult or impossible to measure.

Characterization of Bubble Transport in Porous Media Using a Microfluidic Channel

This study investigates the effect on varying flow rates and bubble sizes on gas–liquid flow through porous media in a horizontal microchannel. A simple bubble generation system was set up to generate bubbles with controllable sizes and frequencies, which directly flowed into microfluidic channels packed with different sizes of glass beads. Bubble flow was visualized using a high-speed camera and analyzed to obtain the change in liquid holdup. Pressure data were measured for estimation of hydraulic conductivity. The bubble displacement pattern in the porous media was viscous fingering based on capillary numbers and visual observation. Larger bubbles resulted in lower normalized frequency of the bubble breakthrough by 20 to 60 percent. Increasing the flow rate increased the change in apparent liquid holdup during bubble breakthrough. Larger bubbles and lower flow rate reduced the relative permeability of each channel by 50 to 57 percent and 30 to 64 percent, respectively.

Removal of powders from cavities in contaminated surfaces by shock and plasma generated by an adjacent electro-static discharge

An electrostatic discharge (ESD) produced between pin electrodes above a cavity filled with powder is explored as means of contactless removal of particles from contaminated surfaces. The ESD is produced by discharging a capacitor through an air gap. Glass beads of different sizes serve as model powders filling cavities of different depths. Masses of both loaded and ejected powders are measured. The motion of the ejected particles is studied using high-speed video. Most of the ejected particles move vertically up with the initial velocities varied from ca. 4 to 11 m/s. Changing the mechanical properties of the substrate holding the powder does not significantly affect the velocities of the ejected particles. For powders removed from cavities as a result of interaction with the shock and plasma produced by ESD, the number of particle layers ejected is determined by the particle size and the ESD energy, but is not significantly affected by the cavity depth. A single ESD pulse can be effective in the complete removal of powder particles from relatively shallow, 0.2-mm deep cavity. Estimates suggest that the particles are primarily ejected due to the lift forces produced by local velocity gradients of the gas above the loaded powder layer.

Model Test of the Water and Sand Mixture Inrush in the Mining-Induced Caving Zone

In western China coal mines, the mining-induced caving zone is regarded as a main pathway for water and sand inrush mixture hazards. The paper experimentally studied the flow behavior and the mechanism of water and sand mixture through mining-induced caving zones. Transport experiments are performed by using a laboratory-scale model, and the caving zone is modelled by using different sizes of glass beads. Four different sand sizes are used for the sand layer. The test results reveal that the mass flow rate of sand and water mixture increases with the increase of the initial water head. And an equation is proposed for the mass flow rate of sand and water mixtures that correctly reproduces the data for all the conditions. In addition, the sudden decreases in water head loss is monitored at the commencement of the water and sand flow, which would result in a large number of sand particles that rapidly start up and make the kinetic energy transfer from water to sand.

Quantification of sonochemical and sonophysical effects in a 20 kHz probe-type sonoreactor: Enhancing sonophysical effects in heterogeneous systems with milli-sized particles

Even though acoustic cavitation has been widely investigated, only few researchers focused on the relationship between sonochemical and sonophysical activities and on the enhancement of sonophysical activity. In this study, sonochemical and sonophysical activities were investigated in a heterogeneous system to understand the relationship between these two activities and to suggest optimal conditions for ultrasonic desorption/extraction processes comprising milli-sized glass beads. The sonochemical activity was quantitatively analyzed using potassium iodide dosimetry in homogeneous and heterogeneous systems. Sonophysical activity was quantitatively and qualitatively analyzed using paint-coated bead desorption tests and aluminum foil erosion tests under three probe positions of “T” (1 cm below the liquid surface), “B” (1 cm above the vessel bottom), and “M” (midpoint between “T” and “B”). Three different sizes of glass beads (diameter: 0.2, 1.0, and 4.0 mm) were used in this study. The highest sonochemical activity was obtained at “B” in both homogeneous and heterogeneous systems. However, three times lower sonochemical activity was observed in the heterogeneous system than in the homogeneous system because significant attenuation and unstable reflection of ultrasound occurred in the bead layer and suspension. Higher sonophysical activity was observed, when the bead size decreased and the probe approached the bottom. However, no significant sonophysical activity was detected when the beads were attached to the bottom. Therefore, the sonophysically active region was the zone around the probe body, opposite to the ultrasound irradiation tip, and only suspended beads could undergo severe cavitational actions. This was confirmed via aluminum foil tests. Several erosion marks on the foil were observed in the area around the probe body, whereas no severe damage was observed at the bottom. Moreover, the degree of sonophysical activity did not change for various saturating gases. This might be due to the different thresholds of sonochemical and sonophysical activities.

Visualization study of polymer enhanced foam (PEF) flooding for recovery of waterflood residual oil: Effect of cross flow

Foam injection is an emerging EOR technology that increases oil recovery by reducing gas mobility, especially in heterogeneous reservoirs with permeability variations. Foam can divert flow from high permeability regions to low permeability regions, provided that its stability is high enough to maintain pressure. In this work, a visualization study of foam flow through a two-layer heterogeneous model is presented and the performance of a surfactant-polymer mixture as the foam stabilizer is evaluated. We compared the efficiency of conventional foam (stabilized by a surfactant) and polymer enhanced foam (PEF) flooding (stabilized by a combination of surfactant and PVA polymer) in the glass bead packed models with three permeability ratios (PR) including 2:1, 4:1, and 8:1. Our particular interest was to visualize the effect of the cross-flow mechanism on PEF performance. To achieve the desired permeability ratio, the model was packed with different sizes of glass beads ranging from 150 to 600 μm. The conventional foam and PEF were injected at the tertiary mode for the recovery of waterflood residual oil. Both foam and PEF injection were significantly more efficient than the gas injection; however, the PEF front advancement was more pistonwise; the ultimate oil recovery by PEF flooding was 15–20% more than the conventional foam flooding in all cases of heterogeneous packed models. At higher permeability contrast of the porous medium that the ability of the foam to sweep the porous medium decreases, the PEF still performs better through the cross-flow mechanism due to its higher stability. This makes the PEF injection a more decent candidate for fractured reservoirs where the heterogeneity contrast is high.

Low-velocity impacts into granular material: application to small-body landing

ABSTRACT With the flourishing number of small body missions that involve surface interactions, understanding the mechanics of spacecraft – surface interactions is crucial for improving our knowledge about the landing phases of space missions, for preparing spacecraft operations, and for interpreting the results of measurements made during the surface interactions. Given their regolith-covered surfaces, the process of landing on a small body can be considered as an impact at low-velocity on to a granular material in reduced-gravity. In order to study the influence of the surface material, projectile shape, and gravity on the collision dynamics, we used two experimental configurations (one for terrestrial gravity experiments and one for reduced-gravity experiments) to perform low-velocity collisions into different types of granular materials: quartz sand, and two different sizes of glass beads (1.5 and 5 mm diameter). Both a spherical and a cubic projectile (with varying impact orientation) were used. The experimental data support a drag model for the impact dynamics composed of both a hydrodynamic drag force and quasi-static resistance force. The hydrodynamic and quasi-static contributions are related to the material frictional properties, the projectile geometry, and the gravity. The transition from a quasi-static to a hydrodynamical regime is shown to occur at lower impact velocities in reduced-gravity trials than in terrestrial gravity trials, indicating that regolith has a more fluid-like behaviour in low-gravity. The reduced quasi-static regime of a granular material under low-gravity conditions leads to a reduction in the strength, resulting in a decreased resistance to penetration and larger penetration depths.

Effects of permeability on CO2 dissolution and convection at reservoir temperature and pressure conditions: A visualization study

When CO2 is injected into aquifers, CO2 will dissolve into the water phase. CO2 dissolution initiated by diffusion, will increase the density of the water phase and thereby commence the convective flow of CO2. The objective of the presented work was to visually investigate the effects of permeability on the convective mixing of supercritical CO2 with water at realistic reservoir conditions (pressure and temperature). This required construction of a high-pressure transparent Hele-Shaw cell that allowed visualization of CO2 transport, and the development of experimental procedures.To develop the high-pressure Hele-Shaw cell, stress/strain calculations and simulations were carried out to select the best building materials for realistic working pressure and temperature and required dimensions to study convection. Porous media of different permeabilities were prepared using glass beads of different sizes. The experiments were carried out at 100 bar and 50 °C using a deionized water solution with Bromothymol blue (BTB) as pH indicator.In the constructed Hele-Shaw 2D-cell, the cell volume was formed by two glass plates separated by an adjustable spacer. In the present study, the cell thickness was 5.0 mm in the main part of the cell volume. The high-pressure Hele-Shaw cell has made it possible to investigate CO2-dissolution and mixing with water at pressures and temperatures realistic for CO2-storage reservoirs in a porous medium for the first time.CO2 mixing and finger initiation in the water phase without the presence of porous media was an instantaneous process. The rate for CO2 dissolution and mixing with water was found to increase with increasing permeability. The CO2 dissolution pattern was found to depend on the permeability. Fingering of CO2-rich high-density water was observed with the highly permeable porous medium. Piston-like displacement was observed in lower permeable porous medium.

Modeling the Thermal Conductivity Inhomogeneities of Injection-Molded Particle-Filled Composites, Caused by Segregation.

Many applications require new materials that have good thermal conductivity, are electrical insulators and can be processed easily and with relatively little energy. A new innovative solution for this problem is thermally conductive composites, which can replace metals in many cases. Many papers have focused on the prediction of their thermal conductivity. At the same time segregation has to be taken into account in the case of composites because it affects the distribution of thermally conductive particles, and thus local thermal conductivities. In this paper, we examined and modeled segregation during injection molding and its effect on thermal conductivity. We injection-molded samples from polypropylene with glass beads of different sizes and analyzed their filler content as a function of the flow path. We described the distribution of the filler with a mathematical model. Using this, we created a new, segregation-dependent model that describes the local thermal conductivity of polymer composites as a function of filler content with great accuracy.

Evaporation From Multilayered Heterogeneous Bare Soil Profiles

AbstractEvaporation from homogeneous and multilayered soil profiles was studied under laboratory conditions using columns packed with different sand types and containers packed with glass beads of different sizes. The impact of positive and negative permeability gradients, and the effect of layer thickness (H), has been investigated. The cumulative evaporation from the fine‐to‐coarse (F‐C) multilayered profile is higher than the one from the coarse‐to‐fine (C‐F) profile. The homogeneous columns evaporate more or less than the multilayered ones depending on the thickness of the layers and the characteristic length of the soil in the top layer. The trends are in agreement with the preliminary results generated by the numerical solution of the flow equations. Cumulative evaporation at the end of stage 1 increases with the layer thickness for the multilayered systems and is larger for the F‐C configuration than for the C‐F one. Glass beads evaporation experiments revealed the existence of a cascade of bursts of air when the invading gas phase reaches the successive fine/coarse layer interfaces in the case of the F‐C configuration. While the evaporation front moves gradually downward during drying in the C‐F multilayered system, it appears to move upward toward the surface in the F‐C multilayered one. It is shown that soil heterogeneity has a significant impact on evaporation. Multilayered soil profiles could be harnessed to reduce water losses or to accelerate drying, depending on the sequence, the thicknesses, and the properties of the layers.

Bed expansion ratio of mono-sized and binary mixtures in fluidized, spouted, and spout-fluid beds

ABSTRACTStudies on bed expansion ratio were carried out in fluidized, spouted, and spout-fluid beds. A single column has been used to compare the characteristics of fluidized, spouted, and spout-fluid beds. Experiments were carried out using air and glass beads under fluidized, spouted, and spout-fluid bed conditions separately to study the effect of gas velocity, bed mass, and particle size on bed expansion ratio. Glass beads of different sizes (0.75, 1.2, 1.7, and 3.075 mm) have been used as solid bed material. Bed expansion ratio was determined for mono-size particles and binary mixtures (different diameter ratios and composition). It was found that the bed expansion ratio decreases with increase in bed mass for only spouting condition and spout-fluidization conditions. The bed expansion ratio increases with increase in bed mass for only fluidization condition.

Experimental and numerical investigation of liquid–solid binary fluidized beds: Radioactive particle tracking technique and dense discrete phase model simulations

Liquid–solid binary fluidized beds are widely used in many industries. However, the flow behavior of such beds is not well understood due to the lack of accurate experimental and numerical data. In the current study, the behavior of monodisperse and binary liquid–solid fluidized beds of the same density but different sizes is investigated using radioactive particle tracking (RPT) technique and a dense discrete phase model (DDPM). Experiments and simulations are performed in monodisperse fluidized beds containing two different sizes of glass beads (0.6 and 1mm) and a binary fluidized bed of the same particles for various bed compositions. The results show that both RPT and DDPM can predict the mixing and segregation pattern in liquid–solid binary fluidized beds. The mean velocity predictions of DDPM are in good agreement with the experimental findings for both monodisperse and binary fluidized beds. However, the axial root mean square velocity predictions are only reasonable for bigger particles. Particle–particle interactions are found to be critical for predicting the flow behavior of solids in liquid–solid binary fluidized beds.

Sediment Resuspension and Transport in Water Distribution Storage Tanks

Computational and experimental studies were conducted to better understand conditions that affect particle resuspension and movement in water storage tanks. Parameters that were investigated included inlet/outlet (I/O) line location and diameter, flow rate, particle size, and filling versus draining cycles. Simulation results showed that smaller particle sizes, higher flow rates, and draining cycles yielded the greatest potential for particle resuspension, which was generally limited to regions near the I/O line. Small‐scale experiments were also performed using different sizes of glass beads and silica sand; the results generally validated the models. Mitigation methods were also presented to reduce the amount of particle resuspension. A pipe that extended from the I/O line into the tank (slightly above the bottom floor) was found to significantly reduce the potential for particle resuspension in both the computational models and experiments.

LAMINAR SETTLING OF GLASS BEADS IN VISCO-PLASTIC LIQUIDS

The paper deals with a determination of the terminal settling velocity of coarse particles in quiescent visco-plastic liquids of Herschel-Bulkley type. Experiments on laminar settling of glass beads of different sizes were conducted in transparent Carbopol solutions of various rheological properties in a sedimentation column. The terminal settling velocity of a solitude bead was determined together with the rheological parameters of the Carbopol liquid. An evaluation of the experimental results confirms the existence of the laminar regime for all tests and compares the measured velocities with predictions by Wilson et al. method. Furthermore, an alternative method is proposed for a prediction of the terminal settling velocity in the laminar regime which uses a particle-based determination of the strain rate in the expression for the equivalent viscosity. A comparison with our experimental results shows that the predictions using the proposed method agree well with the experiments and the proposed method is in the laminar settling regime more accurate than the Wilson et al. method.

Preparation of polylactide microcapsules at a high throughput with a packed‐bed premix emulsification system

ABSTRACTCore–shell polymer microcapsules are well known for their biomedical applications as drug carriers when they are filled with drugs and gas‐filled microcapsules that can be used as ultrasound contrast agents. The properties of microcapsules are strongly dependent on their size (distribution); therefore, equipment that allows the preparation of small and well‐defined microcapsules is of great practical relevance. In this study, we made polylactide microcapsules with a packed‐bed premix emulsification system that previously gave good results for regular emulsions. Here, we tested it for applicability to a system in which droplets shrank and solidified to obtain capsules. The packed‐bed column was loaded with glass beads of different sizes (30–90 µm) at various bed heights (2–20 mm), and coarse emulsions consisting of the polymer, a solvent, and a nonsolvent were pushed repeatedly through this system at selected applied pressures (1–4 bar). The obtained transmembrane fluxes (100–1000 m3 m−2 h−1) were much higher than those recorded for other membrane emulsification techniques. The average size of the obtained microcapsules ranged between 2 and 8 µm, with an average span of about 1; interestingly, the capsules were 2–10 times smaller than the interstitial voids of the beds. The droplets were larger when we used thicker beds and larger glass beads, and these effect correlated with the pore Reynolds number (Rep). Two breakup mechanisms were identified: spontaneous droplet snap‐off dominated the system at low Reps, and localized shear forces dominated the system at higher Rep. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43536.

Effects of different sizes of glass beads on the release of sporocysts from Eimeria tenella oocysts.

The oocyst wall is severed by means of mechanical injury or chemical agents. This study reports the percentage of in vitro sporocyst release following mechanical shaking in the presence of varying sizes of glass beads. Glass beads measured 0.5, 1, and 3 mm in diameter and were shaken with the oocysts for different times ranging from 5 sec to 5 min. Approximately 80% of sporocysts were released with 5 min of shaking in the presence of 3 mm glass beads, as well as 30 sec with 0.5 mm beads and 1 mm glass beads. The release of sporocysts of E. tenella was most efficient using 1 mm glass beads and treatment times of 30 sec to 1 min. Therefore, the use of 1 mm glass beads with 30 sec to 1 min of agitation is recommended in order to maximize sporocyst release and recovery and to improve the yield of viable sporozoites for use in biochemical, tissue culture, and immunological applications of coccidia.

Hydrodynamics of Liquid-Solid Semi-fluidized Bed with Regular Homogenous Ternary Mixture

Hydrodynamics studies in Semi-fluidized bed relating to bed pressure drop, height of top packed bed, minimum and maximum semi-fluidization velocities with regular (spherical glass beads) homogeneous ternary mixtures, have been made in 0.01, 0.025, 0.037, 0.05, and 0.065 m internal diameter Perspex columns, with water as the fluidizing medium. Ternary mixtures of glass beads of different sizes (-8+10, -10+12 and -12+14 BSS) have been used as the semi-fluidized solids. Experimental studies relate to establish the effect of system parameters viz. column diameter, average particle size of semi-fluidized solid and initial static bed height and operating parameters viz. superficial liquid velocity and bed expansion ratio on the above mentioned system variables. Empirical and semi-empirical models have been developed using dimensional as well as statistical analyses. The calculated values from the predicted models have been compared with their experimental counterparts and fairly good agreement has been obtained. The results have also been compared with those available in the literature for irregular homogenous ternary mixtures.

Prediction of bed fluctuation and expansion ratios for homogeneous ternary mixtures of spherical glass bead particles in a three‐phase fluidised bed

AbstractThe prediction of the fluctuation and expansion ratios in three‐phase fluidised beds of homogeneous particles is of prime importance in designing the equipments and evaluating the efficiency of a number of physical and/or chemical operations of industrial importance. A clear knowledge of the hydrodynamic behaviour in a three‐phase fluidised bed is a prerequisite for this purpose. To explore this, a series of experiments have been carried out for homogeneous well‐mixed ternary mixtures of three different sizes of glass beads of varying compositions in a three‐phase fluidised bed. The hydrodynamic characteristics determined include the bed fluctuation and expansion ratios. The dependence of these quantities on the average particle diameter, superficial gas velocity and initial static bed height has been discussed. Based on dimensional and statistical analyses, correlations have been developed with the system parameters, viz., average particle diameter, initial static bed height and superficial velocity of the fluidising medium. Experimental values of bed fluctuation and expansion ratios have been found to agree well with those calculated from developed correlations.

Monitoring accelerated clogging of a model horizontal sub-surface flow constructed wetland using magnetic resonance transverse relaxation times

Horizontal sub-surface flow wetlands are essentially a bed of porous material in which suitable plants are grown to facilitate the removal of organic matter and particulates from wastewater. The aim of this study is to assess the reliability and accuracy of magnetic resonance transverse relaxation time for monitoring clogging development in a constructed wetland. In this study, three different horizontal sub-surface flow constructed wetland models have been produced using tubes packed with different sizes of glass beads with diameter 3, 8 and 14 mm. Accelerated clogging has been achieved by pumping sludge extracted from a real clogged wetland through the bead pack. A desktop MRI tomography system has been used to monitor the transverse relaxation rate as a function of position along the tube and hydraulic conductivity. To corroborate the clogging with magnetic resonance measurements, the head loss was monitored to determine the hydraulic conductivity. Using a bi-exponential fit to the spin echo train data, the slow relaxation rate contribution shows good correlation with the changing hydraulic conductivity. Both fast and slow contributions map well to the expected clog patterns for a constructed wetland. We have demonstrated that there is a linear correlation between the hydraulic conductivity and both parameters of a bi-exponential fit to R 2 eff , but particularly for the case of the short T 2 component.

MRI measurements of dynamic clogging in porous systems using sterilised sludge

Constructed wetlands are used in various stages of wastewater treatment around the world. They usually consist of a gravel matrix in which water loving plants are grown and through which wastewater flows. Over time the gravel matrix becomes clogged as a result of particulates accumulation and biofilm growth. The aim of this study is to investigate the spatially resolved changes in the values of MR parameter T2eff (transverse relaxation time) as the clogging is increased. This provides a better understanding of the pattern and location of clogging. In this study two different sizes of glass beads, 8 and 14mm packed in 1m long acrylic tubes, were used to produce laboratory model systems of constructed wetlands through which sterilised sludge is pumped to provide accelerated clogging. The MSME (Multi Slice Multi Echo) sequence was run on a 2.35 T Bruker Biospec scanner to image at six different locations along the length of the tube during the clogging process. The overall hydraulic conductivity of the system was monitored by measuring the flow rate after every three minutes of accelerated clogging and the pressure drop using take off tube manometers. The sensitivity of T2eff to clogging is shown and the evolution of two well defined peaks can be seen on the corresponding T2eff distributions, respectively due to the presence of bound water and free water. Results demonstrate that T2eff decreases as the clogging is increased and T2eff distributions demonstrate that the information about the amount of free water present inside the tube is essentially described by bi-exponential contributions to the overall signal.