Showing papers in "Particulate Science and Technology in 2012"
TL;DR: In this article, FTIR spectroscopy along with other characterizing method such as x-ray diffraction and xray fluorescence is used for characterization of bentonites.
Abstract: Bentonite particles are widely used for different applications such as drilling fluid, bleaching earth, catalyst, nanoclays, etc. Bentonite is rich in Montmorillonite, which is a nanostructured and nanoporous clay mineral. To characterize bentonite it is important to distinguish different components of clay mineral admixtures from each other and to obtain information regarding their structure, composition, and structural changes. In this research, bentonites are first screened and purified using sedimentation through dispersing 13% concentrations of bentonites in deionized water. FTIR spectroscopy along with other characterizing method such as x-ray diffraction and x-ray fluorescence is used for characterization of bentonites. Adsorption peaks at 524, 466, and 917 cm−1 confirm the presence of montmorillonite. The broadness of 3623 cm−1 peak shows the isomorphic substitution of octahedral Al3+ by Fe2+ or Mg2+ cations which affects the type and properties of studied bentonites. For samples S3 and G1, most o...
35 citations
TL;DR: In this article, the change of key microstructure parameters such as local void ratio, sphericity, angularity, and coordination number of particles was computed over different volumes of REV for porosity.
Abstract: The concept of representative elementary volume (REV) is critical to understand and predict the behavior of effective properties of complex heterogeneous materials in a multiscale manner. Porosity is usually used to define the REV of a given material, if porosity is stationary over consecutive volumetric increments, the sample is considered as REV regardless of the behavior of other microstructure properties. To investigate this common assumption, the change of key microstructure parameters such as local void ratio, sphericity, angularity, and coordination number of particles was computed over different volumes of REV for porosity. X-ray computed tomography was used to obtain three-dimensional volumes of natural sand packed at four different particle fragments. Efficient and robust algorithms were used to compute the microstructure properties from three-dimensional images. Findings revealed that the REVmin for porosity may not be adequate to be considered as a REV for parameters such as particle size dist...
33 citations
TL;DR: In this article, the Coriolis erosion test rig on the lines proposed by Pagalthivarthi and Helmly (1992) has been suitably modified and fabricated to undertake a comprehensive study on different materials.
Abstract: The erosion wear in slurry pumps has been identified as a major problem during transportation of slurry as it affects the equipment performance and reduces its reliability and operation life. To simulate the erosion mechanism in slurry equipments mainly in casing and impeller, the Coriolis erosion test rig on the lines proposed by Pagalthivarthi and Helmly (1992) has been suitably modified and fabricated to undertake a comprehensive study on different materials. In the present experimental study, systematic experiments have been conducted on brass and mild steel specimen to establish the effect of solid particle size, solid concentration and rotational speed on wear. Slurries of fly ash (FA) and mixtures of fly ash (FA) and bottom ash (BA) in the ratio 4:1 and 3:2 have been used at different concentrations in the range of 20 to 65% (by weight). The test results obtained in terms of weight loss have shown that wear has a strong dependence on size of the solid particles and rotational speed where as its var...
32 citations
TL;DR: In this paper, a dual injector is designed in order to increase the pump efficiency, and the efficiency of the new design is found to be at least 30% higher than that of a conventional design.
Abstract: The airlift pump is a device for raising liquids or mixtures of liquids and solids through a vertical pipe, which partially submerged in the liquid, by using compressed air introduced at the lower end of the pipe. Airlift pumps are finding increasing use where reliability and low maintenance are required, and when compressed air or gas are readily available as an energy source for water and oil pumping applications. In comparison with other conventional pumps, the particular merit of the airlift pump is the mechanical simplicity. However, the main disadvantage of these pumps is their low efficiency especially at low liquid submergence ratio. In the present study, a dual injector is designed in order to increase the pump efficiency. The new injector is manufactured and tested for different water submergence ratios. The efficiency of the new design is found to be at least 30% higher than that of a conventional design. A proposed model for the analysis of the pump performance is presented and validated using...
27 citations
TL;DR: In this paper, the formation of the silver nanoparticles was monitored using ultraviolet-visible absorption spectroscopy, cyclic voltammetry, and particle size analyzer and characterized by transmission electron microscopy (TEM) and x-ray diffraction (XRD).
Abstract: In this study, silver nanoparticles were prepared using silver nitrate as the metal precursor, starch as protecting agent, and sodium borohydride (NaBH4) as a reducing agent by the chemical reduction method. The formation of the silver nanoparticles was monitored using ultraviolet-visible absorption spectroscopy, cyclic voltammetry, and particle size analyzer and characterized by transmission electron microscopy (TEM) and x-ray diffraction (XRD). Synthesis of nanoparticles were carried out by varying different parameters, such as reaction temperature, concentration of reducing agent, concentration of silver ion in feed solution, type and concentration of the stabilizing agent, and stirrer speed expressed in terms of particle size and size distribution. Dispersion destabilization of colloidal nanoparticles was detected by Turbiscan. It was observed that size of the starch stabilized silver nanoparticles were lower than 10 nm. The microbial activity of synthesized silver nanoparticles was examined by modifi...
27 citations
TL;DR: In this paper, the concept of critical filling speed, which was proposed to characterize the flowability with special application to die filling, is evaluated and compared with other powder flow characterization techniques.
Abstract: Inter-tablet variations in composition and weight depend on the flowability of pharmaceutical formulations. In this study, the concept of critical filling speed, which was proposed to characterize the flowability with special application to die filling, is evaluated and compared with other powder flow characterization techniques. It has been found that the critical filling speed provides a consistent gauge of the powder flowability with the poured angle of repose, Carr index, Hausner ratio, and flow functions from shear cell testing. However, the mass flow rate and the time to discharge a certain amount of powder through flowmeters showed a different trend, indicating that different powder flow behaviors are involved in these tests. This implies it is necessary to employ a powder flowability measurement technique that mimics the powder flow behavior in the actual application.
23 citations
TL;DR: In this article, the mutual influence of translational and rotational spherical particle movements in calm water was studied using experimental data and numerical simulation, and the results of the experiments focused on the effects of two dimensionless parameters of the particle motion.
Abstract: The mutual influence of translational and rotational spherical particle movements in calm water was studied using experimental data and numerical simulation. Spherical balls with a density close to that of water were speeded up in special devices, which ensured the required ball rotational and translational velocity in the given plane. A video system was used to record the ball trajectory in water. The values of the drag force, Magnus force, and drag torque coefficients were determined experimentally and compared with the results of the numerical simulation of the particle motion. The evaluation of the experiments focused on the effects of two dimensionless parameters of the particle motion: the translational Reynolds number (or Reynolds number) and rotational Reynolds number. The experiments were carried out for the relatively slow (the dimensionless angular velocity Γ < 3.5) and relatively fast (5 < Г < 10) particle rotation. Relationships describing the abovementioned coefficients were developed, takin...
22 citations
TL;DR: In this paper, nanocrystalline S doped titanium dioxide films were successfully prepared by the improved sol-gel process and the as-prepared specimens were characterized using x-ray diffraction (XRD), X-ray energy dispersive spectroscopy (EDS), high-resolution field emission scanning electron microscopy (FE-SEM), Brunauer-Emmett-Teller (BET) surface area, and ultraviolet-visible diffuse reflectance spectrography.
Abstract: The nanocrystalline S doped titanium dioxide films were successfully prepared by the improved sol-gel process. Here TiO(C4H9O)4 and CS(NH2)2 were used as precursors of titania and sulfur, respectively. The as-prepared specimens were characterized using x-ray diffraction (XRD), x-ray energy dispersive spectroscopy (EDS), high-resolution field emission scanning electron microscopy (FE-SEM), Brunauer-Emmett-Teller (BET) surface area, and ultraviolet-visible diffuse reflectance spectroscopy. The photocatalytic activities of the films were evaluated by degradation of organic dyes in aqueous solution. The results of XRD, FE-SEM, and BET analyses indicated that the TiO2 films were composed of nanoparticles. S doping could obviously not only suppress the formation of brookite phase but also inhibit the transformation of anatase to rutile at high temperature. Compared with pure TiO2 film, S doped TiO2 film exhibited excellent photocatalytic activity. It is believed that the surface microstructure of the modified f...
20 citations
TL;DR: In this article, a new procedure for synthesizing micrometric magnetite by hydrothermal decomposition of the Fe-EDTA complex in the presence of urea, starting from Fe(III)-ferric ammonium sulfate and Na4EDTA as main precursors, was developed.
Abstract: We developed a new procedure for synthesizing micrometric magnetite by hydrothermal decomposition of the Fe-EDTA complex in the presence of urea, starting from Fe(III)-ferric ammonium sulfate and Na4EDTA as main precursors. Microcrystals with superparamagnetic behavior with 25–45 μm in size were obtained (5 emu/g at 3.8 kOe magnetic field).
19 citations
TL;DR: In this article, a simple trajectory model is proposed to estimate the vertical position as a function of the horizontal position using a constant horizontal velocity and a vertical acceleration approximated as a power law.
Abstract: A simple trajectory model has been developed and is presented. The particle trajectory path is estimated by computing the vertical position as a function of the horizontal position using a constant horizontal velocity and a vertical acceleration approximated as a power law. The vertical particle position is then found by solving the differential equation of motion using a double integral of vertical acceleration divided by the square of the horizontal velocity, integrated over the horizontal position. The input parameters are: x(sub 0) and y(sub 0), the initial particle starting point; the derivative of the trajectory at x(sub 0) and y(sub 0), s(sub 0) = s(x(sub 0))= dx(y)/dy conditional expectation y = y((sub 0); and b where bx(sub 0)/y(sub 0) is the final trajectory angle before gravity pulls the particle down. The final parameter v(sub 0) is an approximation to a constant horizontal velocity. This model is time independent, providing vertical position x as a function of horizontal distance y: x(y) = (x(sub 0) + s(sub 0) (y-y(sub 0))) + bx(sub 0) -(s(sub 0)y(sub 0) ((y - y(sub 0)/y(sub 0) - ln((y/y(sub 0)))-((g(y-y(sub 0)(exp 2))/ 2((v(sub 0)(exp 2). The first term on the right in the above equation is due to simple ballistics and a spherically expanding gas so that the trajectory is a straight line intersecting (0,0), which is the point at the center of the gas impingement on the surface. The second term on the right is due to vertical acceleration, which may be positive or negative. The last term on the right is the gravity term, which for a particle with velocities less than escape velocity will eventually bring the particle back to the ground. The parameters b, s(sub 0), and in some cases v(sub 0), are taken from an interpolation of similar parameters determined from a CFD simulation matrix, coupled with complete particle trajectory simulations.
17 citations
TL;DR: In this paper, the phase distribution in a two-phase flow field is reconstructed using electric impedance tomography (EIT), which can reconstruct the resistivity/conductivity distribution gradients from electrical data in a medium subjected to arbitrary excitations.
Abstract: Different approaches have been followed to model the hydraulic transport of particles, ranging from pure empirical correlations to general models based on fundamental principles. However, these models suffer from uncertainties associated with the parameters in the constitutive equations and scarcity of experimental data in the literature. Nonintrusive techniques such as electric impedance tomography (EIT) can be used to circumvent the difficulties associated with sampling techniques. EIT is an imaging technique for the phase distribution in a two-phase flow field, allowing reconstructing the resistivity/conductivity distribution gradients from electrical data in a medium subjected to arbitrary excitations. Our best efforts were concentrated on the development of a new EIT system that is analogue based, portable, low-cost, and capable of providing high-quality sharp images when used to characterize the flow of particle suspensions. A voltage source was used, rather than a more complex and costly current so...
TL;DR: In this paper, particles of ethyl cellulose have been precipitated by SAS using CO2 as antisolvent and dichloromethane (DCM) as solvent, and the effects of concentration on the particle size distribution (PSD) of the precipitates were studied.
Abstract: Supercritical antisolvent (SAS) technique is an appropriate process to obtain micro- and nanoparticles The application of this process has, until now, been explored in a variety of different fields including: explosives, polymers, pharmaceutical compounds, colouring matter, superconductors, catalysts, and inorganic compounds Biocompatible and biodegradable polymers are playing more and more important roles in pharmaceutical areas such as tissue engineering and drug delivery Formulation of these polymers into suitable solid-state forms plays an important role in safety, stability, and efficiency of the products Ethyl cellulose is commonly used as drug carrier in controlled delivery systems In this work, particles of ethyl cellulose have been precipitated by SAS using CO2 as antisolvent and dichloromethane (DCM) as solvent We studied the effects of concentration on the particle size distribution (PSD) of the precipitates Ethyl cellulose size-controlled particles have been produced in the micrometer r
TL;DR: In this article, the synthesis and detailed characterization of nanocrystalline lead sulplide (PbS) as gas sensors was reported. But the results of XRD showed respective crystallite sizes of 17.81 and 14.5 µm.
Abstract: Development of nanostructure gas sensing materials is gaining considerable attention at present times. In this light, the present article reports on the synthesis and detailed characterization of nanocrystalline lead sulplide (PbS) as gas sensors. Sol-gel technique was used in preparing undoped PbS nanocrystalline material at two different reaction temperatures (60°C and 90°C) and was characterized by x-ray diffraction (XRD) as well as scanning electron microscopy (SEM). Results of XRD showed respective crystallite sizes of 17.81 nm and 14.5 nm. Synthesized PbS materials on SEM analysis further showed agglomerated crystalline structure. Response of these materials was studied in presence of water vapors as well as various other gases and vapors of organic solvents at various temperatures (25°C to 90°C). The gas sensing behavior showed that the synthesized nanocrystalline materials were influenced predominantly by NH3 and NO2 amongst many other gases at room temperature.
TL;DR: In this article, the suitability of sweet potato and Stevia powders as tablets in terms of their compaction behavior and mechanical strength in comparison to an established pharmaceutical binder; microcrystalline cellulose was evaluated.
Abstract: This study has been conducted to evaluate the suitability of sweet potato and Stevia powders as tablets in terms of their compaction behavior and mechanical strength in comparison to an established pharmaceutical binder; microcrystalline cellulose. The results indicated that the behavior of the material during compression, namely, the plastic and elastic deformations influences the final tablet mechanical strength. Relatively high plastic deformation of a material during compression enhances the contact area for interparticulate bonding, thus, producing a mechanically strong tablet. It was observed that the compaction of stevia powder produces a mechanically stronger tablet in comparison to the sweet potato tablet.
TL;DR: In this paper, the particle contact evolution at die compaction is investigated and the predictive capability of the fundamental assumptions frequently used in theoretical analyses of compaction problems is determined for a uniaxial situation.
Abstract: Cold compaction of composite powders has been analyzed using a discrete element method (DEM). Powder aggregates consisting of up to approximately 10,000 particles and formed by two powder populations with known material strength and size ratios have been compacted both isostatically and uniaxially (die compaction). The particles were assumed constitutively to be perfectly plastic or rigid and as a result, local contacts between the particles were described by a linear force-displacement relation given by previous in-depth analyses of spherical indentation problems. Particular emphasis has been placed on investigating the particle contact evolution at die compaction and to compare the results with previous ones pertinent to the isostatic case. Consequently, the predictive capability of the fundamental assumptions frequently used in theoretical analyses of compaction problems is determined for a uniaxial situation. The main conclusion is that size ratio effects are substantial at die compaction and when suc...
TL;DR: In this article, a molecularly imprinted self-assembled monolayer (SAM) was fabricated on a gold plate by forming a monoline with both thiol compound and the template molecule, and removing the template molecules by solvent extraction.
Abstract: A molecularly imprinted self-assembled monolayer (SAM) was fabricated on a gold plate by forming a monolayer with both thiol compound and the template molecule, and removing the template molecules by solvent extraction. 1-Dodecanethiol (DDT), 1-hexadecanethiol (HDT), [1,1′:4′,1′′-terphenyl]-4-thiol (TPT), and [1,1′:4′,1′′-terphenyl]-4-propanethiol (TPPT) were used as the thiol compounds. Cholesterol was used as the template molecule, and cholesterol, cholic acid, and deoxycholic acid were used as the substrate molecules. Cyclic voltammograms were obtained using these imprinted gold plates as a working electrode, with Ag/AgCl reference electrode and Pt counter-electrode. Potassium ferricyanide was used as a background material for oxidation and reduction. These imprinted monolayers were capable of discriminating cholesterol that had been imprinted. The order of sensing capability of the thiol compounds was TPPT > HDT > TPT > DDT.
TL;DR: In this article, the synthesis of metal sulfide semiconductor nanoparticles of group II-VI was carried out in a high energy ball mill from corresponding metal acetates and sodium sulfide.
Abstract: Synthesis of metal sulfide semiconductor nanoparticles of group II-VI; namely ZnS, PbS, CdS, and CuS; by mechanochemical method was carried out in a high energy ball mill from corresponding metal acetates and sodium sulfide. The samples were continuously milled for 10 h with sample withdrawal at 2 h time interval. Structural properties of nanoparticles were studied by x-ray diffraction (XRD), transmission electron microscope (TEM), and ultraviolet-visible spectra. Particle size distribution and stability of 10 h milled samples were examined using particle size analyzer and Turbiscan. It was found that nanoparticles synthesized by mechanochemical method had mean particle sizes as small as 2–25 nm, low agglomeration, narrow size distribution, and uniformity of particle structure and morphology.
TL;DR: In this paper, the authors investigated the segregation of commercial dry mineral-based construction products and a mixture resembling these in silos of different scale, and the results imply that the quality of the mixture is mainly determined by the segregation induced at filling and by the discharge flow pattern, that is, no segregation mechanisms are active to a significant degree at discharge.
Abstract: The segregation of commercial dry mineral-based construction products and a mixture resembling these has been investigated in silos of different scale, and the results are presented in two parts. This work encompasses the second part, where the relevant segregation mechanisms for the handling of construction materials in silos have been identified through experiments in small scale (0.5 m3). The radial distribution of the particles at filling was determined by sampling from the upper layers of the heap and the influence of different initial conditions on the segregation at discharge was investigated, the overall discharge flow pattern being identified with tracer particles. The results imply that the quality of the mixture is mainly determined by the segregation induced at filling and by the discharge flow pattern, that is, no segregation mechanisms are active to a significant degree at discharge. The findings from the experiments in the small silo were confirmed both in intermediate (20 m3) and large (70...
TL;DR: In this paper, a series of electrically conductive poly(3,4-ethylenedioxythiophene) (PEDOT)/clay nanocomposites were synthesized by using oxidative polymerization of EDOT in the presence of unmodified and modified montmorillonite.
Abstract: A series of electrically conductive poly(3,4-ethylenedioxythiophene) (PEDOT)/clay nanocomposites were synthesized by using oxidative polymerization of 3,4-ethylenedioxythiophene (EDOT) in the presence of unmodified and modified montmorillonite. Modified montmorillonite was treated by dimethyl benzyl octadecyl ammonium chloride. Sodium dodecylbenzene sulfonate (DBSNa) was used as a surfactant in the polymerization of EDOT. PEDOT/montmorillonite (MMT) and PEDOT/organophilic montmorillonite (OMMT) nanocomposites were characterized by using x-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR) means of investigation. Conductivity measurements of the synthesized samples were also taken. Electrical conductivity of the nanocomposites was found to be dependent on the clay content and the methods of preparation. The highest conductivity value, as high as 0.017 Scm−1, was achieved for PEDOT/montmorillonite (MMT). The measure...
TL;DR: In this article, the influence of the geometry of a cylindrical flat-bottomed hopper orifice on the mass discharge rate of six free-flowable powder excipients with the size fraction 0.050-0.063 cm was investigated.
Abstract: In this work, the influence of the geometry of a cylindrical flat-bottomed hopper orifice on the mass discharge rate of six free-flowable powder excipients with the size fraction 0.050–0.063 cm was investigated. Sixteen combinations of the orifice diameter and the height were used. The influence of the orifice diameter was described by the flow equation. However, the discharge rate was also affected by the orifice height. The influence of the orifice geometry on the powder discharge rate was indirectly studied by the parameters of the Beverloo equation. The value of the coefficient of determination and the precision of the discharge rate prediction were the basic criteria. The mean relative differences between the actual discharge rate at the combination of the orifice diameter and its height and the average discharge rate allowed a direct study of the effect of the orifice geometry. The complex nature of the orifice height impact on the powder discharge rate through the hopper opening has been determined...
TL;DR: In this article, the segregation of commercial dry mineral-based construction products and a mixture resembling these has been investigated in silos of different scale, and the results are presented in two parts.
Abstract: The segregation of commercial dry mineral-based construction products and a mixture resembling these has been investigated in silos of different scale, and the results are presented in two parts. This work encompasses the first part, where the segregation of four different construction products at discharge from a 70 m3 silo is followed at a production plant in Finland. In addition, the segregation of two other construction products at discharge from two different 20 m3 silos is determined. Finally, the segregation of a three-component mixture resembling real construction products is investigated in a small (0.5 m3) silo. The results show that a similar segregation pattern, that is, increase of fine material at the end of discharge, is obtained regardless of scale. Although the degree of segregation depends on silo size and material properties, the results of this work show that segregation of commercial construction products in large scale can very well be investigated with idealized mixtures in small sc...
TL;DR: In this paper, a computational fluid dynamics (CFD) method was used to investigate velocity, temperature, particles trajectories, and aerosol concentration in a natural ribbed smoked sheet rubber factory.
Abstract: A computational fluid dynamics (CFD) method was used to investigate velocity, temperature, particles trajectories, and aerosol concentration in a natural ribbed smoked sheet rubber factory. A model to improve the smoke aerosol particle ventilation was proposed. The simulation was performed using turbulent free convection flows where the Rayleigh number was between 5.3838 × 1010 and 33.2003 × 1010. A total of 2,159,347 mesh volumes were applied to the entire ribbed smoked sheet rubber cooperative. Results from the CFD simulation and experiment showed positive results. The air containing smoke particles moved naturally from ventilating lids of the smoke room to the roof. The smoke particles followed the airflow fields at the junction of the roof and traveled to workplace areas. Results show that the thick cloud of smoke particles remained in the workplace after traveling for more than 200 m. Particle concentration was high in the area above the ceiling and lower along the elevation in a downward direction. ...
TL;DR: In this paper, the authors developed equations for estimating the Bond grindability index by the sink-float test data of pumice, and the relationships between the bond grindability and relative densities were stated as simple equations, and calculated values from equations were compared with the experimental results.
Abstract: In this study, equations for estimating the Bond grindability index by the sink-float test data of pumice were developed. Primarily, the cumulative weight and porosity content of the floating fraction were determined for two different pumice samples in all relative densities. Then, grindability of the pumice samples was determined for its constituent specific gravity fractions. Though the grindability of the constituent specific gravity fractions of both the pumices varies in a systematic manner, certain differences, it can be observed in the variation pattern between the two pumices. These differences included easy washability and moderate difficult washability characteristic pumices. The relationships between the Bond grindability and relative densities and between the Bond grindability and porosity were stated as simple equations, and the calculated values from equations were compared with the experimental results. Finally, the float–sink test results can be stated by simple equations relating to the B...
TL;DR: Bentonite is rich in montmorillonite, which is a nanostructured and nanoporous member of smectite group Mineralogical and physicochemical properties play a key role in choosing appropriate bentonites for different applications.
Abstract: Bentonite is rich in montmorillonite, which is a nanostructured and nanoporous member of smectite group Mineralogical and physicochemical properties of bentonites play a key role in choosing appropriate bentonites for different applications Scanning electron microscopy (SEM) reveals the morphological form and size of mineral phase of the studied bentonite samples X-ray diffraction (XRD) analysis showed that the studied bentonites predominantly consist of montmorillonites accompanying other impurities such as quartz, calcite, and plagio feldspar The amount of organic components CHNO (carbon, hydrogen, nitrogen, and oxygen) in the samples was so low that it had no significant effect on the result of XRF analyses X-ray fluorescence (XRF) analysis showed that there was a large amount of Al2O3 in sample ES3 and this large amount of Al2O3 indicates a greater amount of montmorillonite in this sample compared to that in sample GH1 Due to a larger amount of CaO, the type of GH1 montmorillonite is Ca-montmori
TL;DR: In this paper, the trajectories of droplets were evaluated using the Lagrangian approach by solving the equation of droplet motion that included the inertial, viscous drag, Brownian, Saffman lift, and gravity forces.
Abstract: In this study, droplet transport, dispersion, and deposition in a ventilated office with two manikins were studied using a computer-modeling approach. Different airflow distribution systems were used, and an Eulerian approach was employed for the airflow simulation. The trajectories of droplets were evaluated using the Lagrangian approach by solving the equation of droplet motion that included the inertial, viscous drag, Brownian, Saffman lift, and gravity forces. Droplet evaporation was also taken into account by solving the droplet heat and mass transfer equations, thus, allowing for the variation of the droplet size. Mixing and displacement air distribution systems were examined, and trajectories of droplets in the range of 1 to 100 microns emitted by one of the manikins were simulated under a range of conditions. The simulation results showed that the chance for small droplets to leave the room through the exhaust is relatively high. When the mixing air distribution system is used, the drop dispersion...
TL;DR: In this article, the feasibility of using mechanical properties of granulated powder formulations in low to medium pressure regime (i.e., 0.80) was studied. But the feasibility was not evaluated.
Abstract: This research was carried to study the feasibility of using mechanical properties of granulated powder formulations in low to medium pressure regime ( 0.80; that is, demonstrating the feasibi...
TL;DR: In this article, the advantages and disadvantages of all generic control devices are critically appraised for the better understanding by both the designers and users, and the authors outline how such complications could be avoided by developing an understanding on the criteria of selecting air pollution control devices.
Abstract: Industrialization tends to be accompanied by growing population and increasing awareness on environmental problems, making the use of pollution control equipment imperative. However, the air pollution is a complex phenomenon, as the pollutants distributed in the air are molecularly more random than in other media (soil and water). The control of air pollution, therefore, often becomes a more energy intensive process, leading to increased CO2 emissions. Further, air pollution comprises particulate and gaseous pollutions requiring different control philosophies. When the control of both particulate and gaseous pollutants is required in a single step, the selection of equipment is further complicated. This article outlines how such complications could be avoided by developing an understanding on the criteria of selecting air pollution control devices. The advantages and disadvantages of all generic control devices are critically appraised for the better understanding by both the designers and users. Emission...
TL;DR: In this article, 5 and 10% binders were used to determine mechanical properties using a medium pressure (<10MPa) flexible boundary cubical triaxial tester, and the results showed that bulk modulus, compression index, and spring-back index increased with pressure.
Abstract: Pharmaceutical tablets are formed using formulations consisting of ingredients such as filler, binder, disintegrant, and active pharmaceutical ingredients. These ingredients are granulated followed by compaction. In the present study, the granules were formed using 5 and 10% binders. These granulated formulations were tested to determine mechanical properties using a medium pressure (<10 MPa) flexible boundary cubical triaxial tester. Hydrostatic triaxial compression and conventional triaxial compression tests were conducted at 10 and 20 MPa/min loading rates. Fundamental elastic, elastoplastic, and rate-dependent properties such as bulk modulus, compression index, spring-back index, shear modulus, and failure stress were determined from these tests. Some of the key findings were bulk modulus, compression index, and spring-back index increased with pressure. Shear modulus and failure stress increased with confining pressure; Bulk modulus increased with binder content at 10 MPa/min while decreased at 20 MP...
Abstract: In a modern rice mill, de-awning is an important process before husking operation to eliminate awns of the paddy grains for easy conveying in the elevators, chutes, and hopper orifices. This experiment was conducted to study the effects of independent variables of de-awning percentage, orifice cross-sectional area and paddy grains moisture content on the flowing rate (FR) and variations of flowing rate (VFR) of paddy grains through a horizontal hopper orifice. A local paddy variety, namely, Hashemi, which is characterized by long awns was used as a raw material in the test. The results indicated that flow rate (FR) and variations on flow rate (VFR) significantly (p < 0.01) affected by the de-awning percentage, orifice cross-sectional area and paddy moisture content. FR increased from 45.00 to 87.57 g s−1 and VFR decreased from 54.93 to 21.49%, as de-awning increased from 14.67 to 84.93%. FR increased as the orifice cross-sectional area increased from 12.08 to 34.81 cm2; however, higher VFR was obtained at...
TL;DR: In this article, the influence of particle size, pressure drop, and electrostatic charge on the filtration efficiency of electrostatically charged micro-channel filters under cross-flow conditions was modeled.
Abstract: The flow field and filtration efficiency of electrostatically charged micro-channel filters under cross-flow conditions were modeled. In our simulations, the fluid flows tangentially to the filter face (cross-flow). Particles with diameters larger than 2 μm were considered in this study, hence, the effects of Brownian motion were not included in the simulations. The influence of particle size, pressure drop, and electrostatic charge on the filtration efficiency was investigated. Measurements from performing electrostatic force microscopy (EFM) on the monolith sample confirmed the presence of charge and gave a qualitative measurement of the charge distribution. Results from the flow simulations indicate that the electrostatic forces increased the particle capture efficiency only at lower pressure drop. At higher pressure drops, electrostatic forces did not significantly increase the capture efficiency of the particles. Also, the capture efficiency of relatively small particles is found to be more dependent...