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Volume 40, Issue 11
Special Issue for Process Intensification in Fluid and Particle Engineering
Displaying 1-20 of 20 articles from this issue
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Miloš Marek, Zdenek Grof, Petr Kocí, Martin Kohout, Jura ...Article type: Journal Review
2007 Volume 40 Issue 11 Pages 879-889
Published: November 20, 2007
Released on J-STAGE: November 20, 2007
JOURNAL RESTRICTED ACCESSMethodology for the modelling of transport (convection, diffusion, heat conduction), reaction, and phase transformation processes in spatially complex heterogeneous media is reviewed and demonstrated on several application examples, including computer simulations of polymer particle growth and fragmentation, modelling of reaction and diffusion in a catalyst washcoat, and drying of solvent from a static granular bed. The commonalities and differences between each application are discussed, and perspectives on future research directions in multi-scale modelling are provided.View full abstractDownload PDF (6815K) -
Jie Wu, L. J. Graham, N. Noui-MehidiArticle type: Journal Review
2007 Volume 40 Issue 11 Pages 890-895
Published: November 20, 2007
Released on J-STAGE: November 20, 2007
JOURNAL RESTRICTED ACCESSAn overview of the intensification of industrial mixing will be presented. In many instances, it is not sufficient to increase a chemical reaction rate to achieve process intensification, as the rate of a reaction could be limited by mixing, heat transfer and mass transfer. An important strategy for process intensification is to increase mixing rate, heat transfer rate and mass transfer rate. A range of methods are reviewed, for both conventional stirred reactors and alternative forms of reactors, all with the aims of achieving process intensification through enhanced mixing, heat and mass transfer.View full abstractDownload PDF (1808K) -
Jian-Feng Chen, Lei ShaoArticle type: Journal Review
2007 Volume 40 Issue 11 Pages 896-904
Published: November 20, 2007
Released on J-STAGE: November 20, 2007
JOURNAL RESTRICTED ACCESSThis paper reviewed our group work on the high gravity (Higee) technology and its applications to nanoparticles production, which is fulfilled in a rotating packed bed (RPB). Fundamentals of the fluid flow, mass transfer and micromixing in the RPB are discussed. Various pharmaceutical nanoparticles were prepared via reactive precipitation or anti-solvent precipitation in the RPB reactor. CaCO3 nanoparticles dispersion in overbased petroleum calcium sulfonate was produced by in situ synthesis of amorphous nano CaCO3 in microemulsions formed by neutral petroleum calcium sulfonate and CH3OH in the RPB. Commercial production of CaCO3 nanoparticles by the Higee technology has reached a throughput capacity of 36,000 t/y and a typical production line is illustrated and analyzed. As one example of the application of such commercially produced inorganic nanoparticles, polymer-based nanocomposites were produced by adding CaCO3 nanoparticles into different polymer matrixes such as PVC, ABS, PP, etc., and it was observed that nano CaCO3 significantly improved the mechanical properties of the polymer matrixes.View full abstractDownload PDF (1415K) -
Keita Okuda, Yuusuke Sugikawa, Toshihisa UedaArticle type: Research Paper
2007 Volume 40 Issue 11 Pages 905-912
Published: November 20, 2007
Released on J-STAGE: November 20, 2007
JOURNAL RESTRICTED ACCESSEffect of periodical injection of branching flows perpendicular to the laminar main flow is investigated experimentally and numerically. The periodical injection forms a regular alternative layer of main flow fluid and branching flow fluid. The boundary between main flow fluid and the branching flow fluid is stretched and folded by the parabolic laminar velocity profile in the main flow. The importance of the duty ratio of the branching flow injection, the number of branching flows and the phase of branching flows are discussed.View full abstractDownload PDF (2984K) -
Takashi Goshima, Koichi TerasakaArticle type: Research Paper
2007 Volume 40 Issue 11 Pages 913-919
Published: November 20, 2007
Released on J-STAGE: November 20, 2007
JOURNAL RESTRICTED ACCESSWhen both a gas and liquid are simultaneously introduced into a microreactor, slug bubble flow is often observed. To properly design the microreactor, the estimation of the slug bubble size is very important. In this study, therefore, the slug bubble formation mechanism at a micronozzle inserted into a capillary tube was investigated. The effects of the gas flow rate, nozzle diameter, capillary diameter and liquid velocity on the bubble shape and volume were experimentally examined. To clarify the dynamic behavior of a slug bubble at a micronozzle, the slug bubble formation model was proposed. Bubble volumes, bubble growth curves and bubble shapes experimentally obtained in this study are well predicted by the present model.View full abstractDownload PDF (1198K) -
Shunji Homma, Kozue Akimoto, Jiro Koga, Shiro MatsumotoArticle type: Research Paper
2007 Volume 40 Issue 11 Pages 920-927
Published: November 20, 2007
Released on J-STAGE: November 20, 2007
JOURNAL RESTRICTED ACCESSThe breakup of a laminar liquid jet into drops in non-Newtonian immiscible liquid systems has been studied using a two-dimensional cylindrical axisymmetric front-tracking/finite difference method with the Carreau–Yasuda model for non-Newtonian viscosities. For co-flow condition, where the continuous phase flows with the same velocity as the jet injection velocity, the lengths of the jet and the sizes of the drops are in good agreement between numerical simulations and experiments reported previously. Non-Newtonian effects are discussed by visualizing the distribution of viscosity. The breakup length of the jet becomes large when shear thinning occurs inside the jet, while the jet becomes short when shear thinning occurs in a continuous phase.View full abstractDownload PDF (2194K) -
Hiromoto Susawa, Toshihiro Tsuji, Takashi Jimbo, Tetsuo SogaArticle type: Research Paper
2007 Volume 40 Issue 11 Pages 928-938
Published: November 20, 2007
Released on J-STAGE: November 20, 2007
JOURNAL RESTRICTED ACCESSA diffusion-limited model has been used to describe supersaturation in liquid phase epitaxy (LPE). LPE is not often treated in chemical engineering, but the equations in a diffusion-limited model are similar to those used in thermal engineering. Therefore, we can deal with these equations analytically and solve them numerically. This paper solves the problem that the numerical solutions of the diffusion-limited model depend on the mesh sizes and comprises two parts. The first part provides an update of the traditional equation to describe the initial condition in the diffusion-limited model. The second part is a proposal of methods to calculate the compositional variation using the diffusion-limited model. The mesh sizes for the numerical simulations are determined systematically to calculate the solid phase composition within a desired tolerance limit.View full abstractDownload PDF (459K) -
Mitsuhiro Ohta, Daisuke Kikuchi, Yutaka Yoshida, Mark SussmanArticle type: Short Communication
2007 Volume 40 Issue 11 Pages 939-943
Published: November 20, 2007
Released on J-STAGE: November 20, 2007
JOURNAL RESTRICTED ACCESSWe present the computational results of the dynamics of single bubbles slowly formed from a submerged nozzle in a viscous liquid. Our simulations are carried out by a sharp interface coupled level set/volume-of-fluid (CLSVOF) method and the governing equations based on the CLSVOF method are solved through a hydrodynamic scheme with formal second-order accuracy. The application of two-phase computational fluid dynamics (CFD) for simulating bubble formation dynamics in a viscous liquid is a challenging task. We present unique, quantitative, comparisons between the results from CFD and experimental observations. As a result, it is shown that our computational method is robust to extreme variations in physical properties and extreme variations in interfacial topology, and it is shown that our method gives accurate results.View full abstractDownload PDF (603K) -
Hideki Kawai, Hiroshi Kudo, Hiroshi TakahashiArticle type: Research Paper
2007 Volume 40 Issue 11 Pages 944-950
Published: November 20, 2007
Released on J-STAGE: November 20, 2007
JOURNAL RESTRICTED ACCESSThe purpose of the present study is to experimentally visualize the limit cycle orbit, which has previously only been confirmed numerically in multi-phased Taylor vortex flow (TVF). In the limit cycle, solid particles are gathered in a very limited orbit line. While this phenomenon is unique and does not occur in the general flow region, it is useful for analyzing the anti-plugging characteristics in industrial rotating filter devices. The limit cycle orbit is formed around the central region of each vortex cell as a closed toroidal curvature. In each vortex cell, solid particles approach the limit cycle orbit with time due to the interaction of forces that occurs between fluids and particles. In the present study, experimental visualization of the limit cycle orbit is performed using a TVF device with a short annulus, which has a unique self-excited oscillation mode and could be applied to gentler and more efficient mixing reactors. This orbit appears to be strongly related to the isolated mixing regions, which have been studied previously, that form mainly in the central region of the vortex cell. In addition, we discuss the relationship between the limit cycle orbit and the isolated mixing regions.View full abstractDownload PDF (5252K) -
Mohamed Nabil Noui-Mehidi, Naoto Ohmura, Kazuki Nishiyama, Jie WuArticle type: Research Paper
2007 Volume 40 Issue 11 Pages 951-956
Published: November 20, 2007
Released on J-STAGE: November 20, 2007
JOURNAL RESTRICTED ACCESSA numerical study has been conducted to determine the effect of radial heating on the stability of Taylor vortices in a system formed by concentric conical cylinders. The outer conical cylinder is stationary while the inner conical cylinder rotates. Both conical cylinders have the same apex angle resulting in a constant annular gap. The study of the effects of the introduction of buoyancy on the flow properties has been accomplished by considering both conical cylinders to be isothermal, the inner conical cylinder at a higher temperature than the outer conical cylinder. The calculations are achieved by the use of a Simplified Marker and Cell algorithm using a staggered mesh grid. The investigation is concerned with radius ratios of 0.8 defined at the top of the flow system. The results have shown that the apex angle affected the symmetry of the flow structures and the heat transfer mechanism. It was revealed through the Nusselt number that the overall heat transfer increased when the apex angle was increased.View full abstractDownload PDF (1626K) -
Takashi Saeki, Nobuhiro Ohtake, Kenji ImaiArticle type: Research Paper
2007 Volume 40 Issue 11 Pages 957-963
Published: November 20, 2007
Released on J-STAGE: November 20, 2007
JOURNAL RESTRICTED ACCESSDrag reduction caused by surfactant solutions is considered to be an effective way to reduce the running cost in closed-loop district heating and cooling systems. Conversely, much research has pointed out that heat transfer reduction occurs simultaneously for drag reducing flows. In this study, drag reduction and heat transfer characteristics were measured for drag-reducing additives with two cationic surfactants of different concentrations, particularly in a higher temperature range, that cross the upper limit temperature of drag reducing solutions. Information on what occurs at this higher temperature range is necessary for design and operation with considering heating processes.View full abstractDownload PDF (599K) -
Myung-Geun Koh, Chongyoup KimArticle type: Research Paper
2007 Volume 40 Issue 11 Pages 964-972
Published: November 20, 2007
Released on J-STAGE: November 20, 2007
JOURNAL RESTRICTED ACCESSIn this experimental study, we have investigated the separation of particles with different sizes dispersed in liquids using the flow through branched capillaries. We investigated four different kinds of fluids of a Newtonian fluid, shear thinning fluid, non-shear thinning elastic fluid and shear thinning and elastic fluid. Only in the shear thinning fluid, the separation of large particles from a mixture of particles with different sizes was achieved. This separation has been found to be possible because of the fast migration of non-interacting particles across streamlines and the proper partitioning characteristics at the branch in shear thinning fluids. From the experimental results it has been concluded that the scale down of the system to miniaturize the system will be possible and therefore the process intensification can be achieved.View full abstractDownload PDF (511K) -
Kanako Kameyama, Yoshiyuki Komoda, Hiroshi Suzuki, Hiromoto UsuiArticle type: Research Paper
2007 Volume 40 Issue 11 Pages 973-979
Published: November 20, 2007
Released on J-STAGE: November 20, 2007
JOURNAL RESTRICTED ACCESSThe improvement of the strength and structure of a porous titanium dioxide (TiO2) thin film on a plastic film substrate as an electrode for dye-sensitized solar cells (DSCs) were investigated. Although a film type DSC is lightweight and flexible, it shows a poor binding to a substrate compared with a glass type DSC. By the use of the ordinary TiO2 slurry including a volatile solvent the thin film forms a lot of cracks during the drying process because of a rapid removal rate of the solvent and a strong interaction between TiO2 particles. In this study, we prepared well dispersed TiO2 slurry by using a planetary ball mill and it was condensed by centrifugal sedimentation. High concentration slurry is appropriate for the coating and drying because it has a small amount of solvent and good stability of liquid film after the coating. Further, the crack produced on the surface of the thin film could be reduced in a slow drying process by the control of the pressure and atmosphere. The TiO2 thin film, which was produced by the improved methods of slurry preparation and drying condition, showed good cohesiveness to a plastic film substrate.View full abstractDownload PDF (1951K) -
Dariusz Gudin, Junya Kano, Fumio SaitoArticle type: Research Paper
2007 Volume 40 Issue 11 Pages 980-985
Published: November 20, 2007
Released on J-STAGE: November 20, 2007
JOURNAL RESTRICTED ACCESSAn influence of the operating parameters on the grinding performance of the wet bead mill has been researched experimentally and by using a simulation technique based on the discrete element method (DEM). The rotational speed of the agitator, the beads filling ratio, their diameter and material, and the slurry concentration were the subjects of the investigations. The grinding rate constant of the gibbsite sample was determined experimentally and compared with the specific impact energy calculated from the velocity of the grinding beads simulated. An increase in the rotational speed of the agitator and in the filling ratio and a decrease in the slurry concentration cause an increase in the grinding rate constant. A similar effect of the operating parameters on the specific impact energy has been observed.View full abstractDownload PDF (1025K) -
Shinichi Ookawara, Madhusuden Agrawal, David Street, Kohei OgawaArticle type: Research Paper
2007 Volume 40 Issue 11 Pages 986-992
Published: November 20, 2007
Released on J-STAGE: November 20, 2007
JOURNAL RESTRICTED ACCESSA Macroscopic Particle Model (MPM), which can be regarded as a quasi direct numerical simulation and hence does not need any drag and lift force models, is applied to examine the effect of particle density on lift force-induced separation in a micro-separator/classifier. The computational domain is a 30-degrees arc channel with a radius of 20 mm connecting to 5-mm straight channels at the both ends. In this study the modeled is an upper-half of the channel with a width of 200 μm and a depth of 75 μm. The particle diameter was chosen to be 20 μm, which is well separable in experiments and is suitable for MPM in which a particle should contain several fluid cells. The density was examined in the range of slightly lighter to denser, compared with water. The particle trajectories from representative points are predicted by MPM and also by a traditional particle tracking method (DPM) for comparison. The DPM without a lift force model predicted that the trajectories expanded over the cross-sectional plane with an increase of particle density since a secondary flow pattern called Dean vortices caused strong centrifugal force acting outwards from its center. On the other hand, the trajectories predicted by MPM were almost confined in the outer-half of the plane due to the lift force acting inwards to the vortex center. It seems that encountering lift force due to a steep shear and centrifugal force due to the Dean vortices are balanced regardless of the particle density since both forces likely increase with particle inertia. It is notable that particles can be hydraulically separable regardless of the density ranging slightly lighter to denser compared to the medium.View full abstractDownload PDF (1371K) -
Lei Li, Yoshimasa Urushihara, Junji MatsuiArticle type: Research Paper
2007 Volume 40 Issue 11 Pages 993-998
Published: November 20, 2007
Released on J-STAGE: November 20, 2007
JOURNAL RESTRICTED ACCESSSupercritical carbon dioxide was used as a solvent to modify a nanofiller using small amounts of dispersing additives and a silane coupling agent to obtain modified, non-agglomerated dry nanoparticles. Two types of silica (mono-dispersed, non-agglomerated silica and agglomerated silica) were used in this research, with the silica particles modified by three kinds of dispersing additives and two kinds of silane coupling agent. The particle dispersion and size of the obtained silica particles were evaluated by small angle X-ray scattering (SAXS). An extensive physicochemical evaluation of the obtained modified silica particles was also conducted using Fourier transform infrared (FTIR) analysis. It was found that the silica particles possess mono-dispersed and non-agglomerated properties, and that the surface silanol group of the silica particles reacts with hydrolysable silane alkoxy groups.View full abstractDownload PDF (1020K) -
Takashi Ueda, Yoshiuki Komoda, Hiromoto UsuiArticle type: Research Paper
2007 Volume 40 Issue 11 Pages 999-1006
Published: November 20, 2007
Released on J-STAGE: November 20, 2007
JOURNAL RESTRICTED ACCESSThe swelling rate of latex polymer particles in seed coagulation was shown to be influential in determining the final morphology of the assembly of the latex particles. In the present work, droplets of various monomeric species were used as the coagulation seeds. The latex particles form assemblies by seed coagulation which starts on the surface of the monomer droplets. Assemblies with a dense shell formed when the latex particles swell with the monomer slowly enough to allow the latex particles to densely stack. The layer-by-layer immobilization of the latex particles proceeds without losing the spherical morphology of the individual assemblies. In this case, the final coagulation assembly is obtained as a spherically aggregated flock of the latex particles with a cavity in its center. On the other hand, the primary coagulation layer forms a monolithic hollow structure (shell) in the case where the latex particles on the monomer droplets entirely and rapidly swell before the second coagulation layer is completed. Subsequently, a sparse porous layer of the latex particles forms on the outer surface of primarily formed monolithic inner shell.View full abstractDownload PDF (2237K) -
Michiaki Matsumoto, Masakazu Mikami, Kazuo KondoArticle type: Short Communication
2007 Volume 40 Issue 11 Pages 1007-1010
Published: November 20, 2007
Released on J-STAGE: November 20, 2007
JOURNAL RESTRICTED ACCESSOrganic nitrogen and sulfur compounds were separated from model fuels with supported liquid membranes using ionic liquids, based on 1-alkyl-3-methylimidazorium and quaternary ammonium salts. The organic nitrogen and sulfur compounds selectively permeated the membranes. Liquid membranes that used more hydrophilic ionic liquids yielded higher selectivity. The ionic liquids were retained in membrane pores after ten times repeated experiments. Application of supported liquid membranes based on ionic liquids has potential for the separation process of organic nitrogen and sulfur compounds from the fuels.View full abstractDownload PDF (363K) -
Jian Zou, W. S. Winston HoArticle type: Research Paper
2007 Volume 40 Issue 11 Pages 1011-1020
Published: November 20, 2007
Released on J-STAGE: November 20, 2007
JOURNAL RESTRICTED ACCESSIn this study, a process combining carbon dioxide removal by using a polymeric membrane with a subsequent water gas shift (WGS) reaction was developed to purify hydrogen for fuel cells. The polymeric CO2-removal membranes were synthesized by incorporating amino acid salts and polyamine into crosslinked poly(vinyl alcohol). The membranes showed high CO2 permeability and CO2/H2 selectivity in temperatures ranging from 110 to 170°C. A rectangular membrane permeation cell with well-defined countercurrent gas flows was used to study the CO2 removal. A feed gas consisting of 1% CO, 17% CO2, 45% H2, and 37% N2 was used to simulate the synthesis gas from autothermal reforming of gasoline with air. With this permeation cell running at 120°C, the CO2 concentration in the gas mixture was reduced from 17% to as low as 10 ppm, resulting in more than 99.5% of CO2 removed. Then, with another feed gas consisting of 1.19% CO, 0.10% CO2, 53.87% H2, and 44.84% N2 used to simulate the synthesis gas after the CO2-removal step, a reactor packed with a commercial low-temperature WGS catalyst was operated at 140–150°C to convert CO to H2. With such a low CO2 concentration in the feed gas, the reversible WGS reaction was shifted forward so that the CO concentration was decreased from 1.19% to less than 10 ppm (on dry basis), which met the requirement of proton-exchange membrane fuel cells. The WGS reactor had a gas hourly space velocity of 7650 h–1 at 150°C, and the H2 concentration in the exit was more than 54 mol% (on dry basis).View full abstractDownload PDF (715K) -
Magdalena Kristiawan, Vaclav Sobolik, Mazen Al Haddad, Karim AllafArticle type: Research Paper
2007 Volume 40 Issue 11 Pages 1021-1029
Published: November 20, 2007
Released on J-STAGE: November 20, 2007
JOURNAL RESTRICTED ACCESSDry cananga (Cananga odorata Hook. fil. et Thomson, forma macrophylla) flowers were steamed for a short time after which an abrupt pressure drop into a vacuum (about 5 kPa) was applied (DIC process). This pressure drop provoked auto-vaporization of the volatile compounds, puffing of flowers, breaking of cell walls, and cooling. The yields of major volatile compounds of the cananga oil obtained from the condensate were studied as functions of heating time (0.5 to 20 min) and cycle number (1 to 8) at different steam pressures (0.2 to 0.6 MPa). The results of DIC isolation and steam distillation (SD) were compared. A satisfactory yield of oil without thermal degradation was obtained using several DIC cycles with a high steam pressure (0.6 MPa) and short heating time (<1 min). The quantity of the oil obtained by SD in 12 h was isolated by DIC in 4 min. The quality of DIC oil was better because it contained more light and heavy oxygenated compounds (LOC and HOC) than the SD oil. The DIC isolation kinetics leads to the conclusion that sesquiterpenes and LOC are located in the exogenous site and a majority of HOC in the endogenous site.View full abstractDownload PDF (783K)
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