鈴木 洋 | ![]() |
スズキ ヒロシ | |
大学院工学研究科 応用化学専攻 | |
教授 | |
応用化学関係 |
2021年05月 日本レオロジー学会, 日本レオロジー学会学会賞, 熱輸送の高効率化に対する希薄溶液および微粒子分散系レオロジーの応用
2020年06月 日本伝熱学会, 日本伝熱学会学術賞, 硬殻マイクロカプセル化蓄熱材による未利用熱利用に関する研究
2020年01月 Organizing Committee of the 15th International Workshop for East Asian Young Rheologists, The Best Poster Award of NIHON RHEOLOGY GAKKAISHI, Effects of Relaxation Time of Polyethylene Oxide Solutions on Vortex Deformation and Turbulence Statistics in Two-Dimensional Turbulent Flow
2019年10月 第67回レオロジー討論会実行委員会, 優秀ポスター発表賞, 走査型プローブ顕微鏡を用いた高分子の流動抵抗実測と流体中の高分子形態予測
2017年10月 第65回レオロジー討論会実行委員会, 優秀ポスター発表賞, 粘弾性液滴の壁面衝突挙動に関する研究
2015年03月 化学工学会, 第80年会ポスター発表奨励賞, 変色反応および脱色反応を用いた正逆交互回転翼撹拌における混合過程の評価
2013年03月 化学工学会, Outstanding Paper Award of Journal of Chemical Engineering of Japan, Onion-like Structure of Viscoelastic Surfactant Solution Flow Induced by 4-Blade Paddle Impeller in a Vessel
2013年03月 化学工学会粒子流体プロセス部会, 化学工学会粒子流体プロセス部会動画賞, 正逆交互回転翼の振動条件が槽内流動状態に及ぼす影響
2011年03月 化学工学会, 化学工学会研究賞, 潜熱保有微粒子スラリー輸送によるプロセス強化に関する研究
2009年11月 Organizing Committee of Fluid and Thermal Energy Conversion 2009, Best Paper Award in FTEC 2009, Experimental Study on Water Based Mixture of Coconut Oil and FAME-Rich Mixture to be Use as Secondary Refrigerant in Air Conditioning System
2008年05月 日本レオロジー学会, 日本レオロジー学会論文賞, Structure Analysis of Drag-Reducing Surfactant Rod-like Micelles with Fluorescence Probe
2008年03月 化学工学会, 化学工学会技術賞, 新静止型流体混合・分散器の開発
2007年03月 化学工学会粒子流体プロセス部会, 化学工学会粒子流体プロセス部会技術賞, 新静止型流体混合・分散器の開発
2005年 China/USA/Japan Joint Chemical Engineering Conference, Best Poster Award of China/USA/Japan Joint Chemical Engineering Conference, Latent Heat of Ice Slurries Treated with Surfactant
2004年11月 はりま産業振興会, はりま産業振興会シーズコンペ大賞, すべる水とひっつかない微粒子
1990年05月 日本伝熱研究会, 森康夫学術賞, 円柱によってかく乱を受ける乱流境界層(円柱径および円柱挿入位置の影響)
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Complex fluids have a non-uniform local inner structure. The non-uniformity of polymer and worm-like micellar solutions were characterized by the local viscosity distribution obtained by optical tweezers with the inverse integral transformation method.
Royal Society of Chemistry ({RSC}), 2020年, Soft Matter, 16 (29), #6826 - 6833[査読有り]
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Ammonium alum hydrate is a promising material for a latent heat transportation system for higher temperature around 50 °C. However, there were two big problems to be solved. One is a low fluidity of the slurries due to increasing the viscosity the other is a sedimentation of phase changed ammonium alum hydrate particles in the slurry due to high density of the particle, which causes pipe blockage. In this study, in order to solve these problems, we added drag reducing surfactants and polyvinyl alcohol (PVA) to the ammonium alum hydrate solution, and investigated the effects of them. Particle growth and sedimentation of ammonium alum in the solution were prohibited by adding both surfactants and PVA. Addition of only PVA to ammonium alum solution didn't prevent the particle growth and the sedimentation. That is, the effect was a synergetic effect. In order to understand the synergetic effect, inner structures of a solution containing surfactants and PVA were measured by a dynamic light scattering (DLS). Flow and heat transfer characteristics were also measured and analyzed. Friction coefficients of solutions and slurries were decreased with the drag reducing surfactants, which was not affected by addition of PVA. Heat transfer characteristics of ammonium alum hydrate slurries were higher than that of solution with surfactants and PVA. All the results confirmed the applicability of the ammonium alum hydrate slurries for the high temperature latent heat transportation systems.
Elsevier Ltd, 2018年09月01日, International Journal of Heat and Mass Transfer, 124, 1334 - 1346, 英語[査読有り]
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An experimental study was performed to investigate the relationship between the extensional rheological properties of polymer solutions and vortex deformation in turbulent flow. Polyethyleneoxide as a flexible polymer and hydroxypropyl cellulose as a rigid polymer are added to two-dimensional (2D) turbulent flow. Specifically, 2D flow is advantageous as it examines the effect of the extensional rheological properties of polymers on the flow. In the study, 2D turbulent flow and vortex shedding in 2D turbulent flow were observed using interference patterns and particle image velocimetry (PIV). Power spectrum of the 2D flow images and 2D turbulence statistics calculated by PIV analysis indicated that there are three flow regimes of vortex shedding in the 2D turbulent flow of the polymer solution. The vortex shedding in the 2D flow was categorized into three types, and this was affected by the relaxation time of the polymer solutions.
Elsevier B.V., 2018年04月01日, Journal of Non-Newtonian Fluid Mechanics, 254, 1 - 11, 英語[査読有り]
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In order to clarify the mechanism of the bulge structure appearance observed in a cavity swept by a visco-elastic fluid, velocity fields were measured by a two-dimensional particle image velocimetry (PIV). The rib height, the cavity length, the flow path height and the flow path width were fixed at 20 mm, 100 mm, 40 mm and 75 mm, respectively. The Reynolds number was also fixed at 1,700 where the bulge structure appeared as reported by the previous study. The spanwise positions of the two-dimensional PIV were changed in 6 steps from the center plane to the outer region. From the results, it was found that the bulge structure has high-level fluctuation and its intermittency is related to the longest relaxation time. The bulge structure appears when the main flow separated from the upstream top corner of the cavity is intensified. The separated main flow contracted in the former cavity region expands not only toward the cavity bottom but also toward the outside walls of the flow path. In order to supply the fluid in the center plane, the backward flow occurs in the cavity. This flow motion was concluded to be a basic mechanism of the bulge structure appearance.
Society of Rheology, 2018年, Nihon Reoroji Gakkaishi, 46 (1), 29 - 36, 英語[査読有り]
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Extensional flow properties of dilute viscoelastic solution have attracted much attention for almost three decades. This is because extensional viscosity or relaxation time of viscoelastic solution under extensional stresses add a lot of impact on fluidity of the solution the phenomenon is related to many industrial applications. Several techniques were proposed and many studies were conducted to measure extensional properties of polymer solutions. However, less studies were reported in the case of non-uniform solution, such as suspensions. In this study, we propose a relatively simple method to measure extensional viscosity. We adopt a syringe-shape abrupt contraction channels for the measurement the syringe-shape apparatus is useful to contain non-uniform dilute solutions. As a first step to develop the experimental apparatus and method, we tested polymer solutions. Polymers used to prepare sample solutions were polyethylene oxide (PEO), hydroxypropyl cellulose (HPC) and polyacrylic acid (PAA). Each polymer has different flexibility, which cause different characteristics of the extensional viscosity of polymer solutions. Extensional viscosities obtained in this study detected the characteristic of each polymer solution. Extensional viscosities of PEO solution was increased by increasing extensional rates that of HPC and PAA solution were decreased by increasing extensional rates the tendency was explained by relaxation times of each polymer solution.
Society of Rheology, 2018年, Nihon Reoroji Gakkaishi, 46 (1), 13 - 22, 英語[査読有り]
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We previously reported that a rotationally reciprocating impeller, which slowly rotates back and forth with a sinusoidal change in the rotational speed, can realize superior mixing performance even under moderate fluid flow. In the case of crystallization process, it is expected that the rotationally reciprocating mixing suppresses crystal brakeage caused by collision to impeller plate and inhomogeneous supersaturation due to notable mixing performance. In the present study, we studied reactive crystallization process of salicylic acid and investigated the effect of mixing conditions on the size and shape of crystals. For a steady rotational mixing, the largest crystal size was obtained at the appropriate mixing condition, and the size and shape of crystals are both affected by the rotational speed. Meanwhile, it is found that the size of crystals maintained roughly constant in the wide range of mixing condition of the rotationally reciprocating mixing. Additionally, no significant difference in the shape was observed even at different reciprocating conditions.
Society of Chemical Engineers, Japan, 2018年, Journal of Chemical Engineering of Japan, 51 (2), 159 - 165, 英語[査読有り]
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To investigate the sedimentation and flow characteristics of hard-shell microcapsule/water slurries, the apparent viscosity, apparent dispersion volume fractions, and friction characteristics were measured. The hard-shell microcapsule contains disodium hydrogen phosphate hydrate as a phase change material. Poly (vinyl alcohol) (PVA) with a concentration from 0 to 2,000 ppm was applied as a dispersant. A drag-reducing surfactant system was also added to the slurries to improve the flow characteristics of the slurries. As a drag-reducing surfactant, oleylbishydroxyethylmethylammonium chloride was added at 2,000 ppm with a counter-ion of sodium salicylate. As a trial, the concentration of microcapsules was set at a low value at 1 or 2 wt%. From the results, severe adsorption of surfactants onto the hard-shell microcapsules was found. Then, no drag reduction or sedimentation prevention occurred in the cases without PVA. However, there is a weak sedimentation prevention effect and effective drag reduction effect when PVA is present. Thus, it is concluded that the desorption of surfactants from the microcapsules occurs and forms a synergetic structure with the PVA.
International Institute of Refrigeration, 2018年, Refrigeration Science and Technology, 2018-, 174 - 181, 英語[査読有り]
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For effective use of excess exhaust heat from gas engines, a novel PCM was prepared by adding anhydrous sodium sulfate and D-mannitol to ammonia alum hydrate. It melted and stored latent heat at the temperature range of exhaust heat from gas engines (around 90°C). Heat storage and release characteristics of the novel PCM were investigated with a heat storage tank containing hot water and the novel PCM packaged into resin bags. As a result, the novel PCM stored and released more than 400 MJ×m-3 of heat at the temperature range between 80°C and 90°C. The amount of heat storage and release by the PCM was approximately ten times higher than that of water with same volume. This result indicates that the novel PCM can reduce the volume of hot water tank dramatically in addition to storing and releasing exhaust heat from gas engines.
International Institute of Refrigeration, 2018年, Refrigeration Science and Technology, 2018-, 214 - 221, 英語[査読有り]
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The fabrication method of silica hard shell microcapsules containing disodium hydrogen phosphate dodecahydrate (Na2HPO4 center dot 12H(2)O) has been developed. The effects of the mixing rates for the emulsification, of the volume ratios of solutions and of surfactant concentrations on the size of hollow microcapsules have been also studied. From the results, it was confirmed that silica hard shell microcapsules can contains Na2HPO4 center dot 12H(2)O with the present method using hollow microcapsules. The present micro-encapsulated Na2HPO4 center dot 12H(2)O was also found to cause the supercooling depression effect. As the fabricated microcapsules have no flammability, the present microcapsule was concluded to be a promising item not only for latent heat transportation media but also for the static thermal storage materials for architectural structures. From the studies on the fabrication parameters, it was concluded that the control of the surfactant concentration is effective for controlling the size of microcapsule. (c) 2017 Elsevier Ltd and IIR. All rights reserved.
Elsevier {BV}, 2017年10月, International Journal of Refrigeration, 82, 97 - 105, 英語[査読有り]
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The present study deals with the flow field in the circular cross section of a cylindrical vessel induced by a rotationally reciprocating impeller, rotating back and forth with gradual change in rotational speed. A periodically stable velocity field was measured by PIV and also simulated by CFD. It was revealed that the velocity field near the liquid free surface is basically 2-dimensional, except for the acceleration period at Re = 43, and agrees well with 2-dimensional CFD simulation, except for the development process of 3-dimensional tip vortices at Re = 43. The separation behavior of the vortices originally generated at the impeller tip changed with increasing Reynolds number. No separation was observed at a lower Reynolds number, while the separated vortices turn into 3-dimensional potential vortices and remain as 2-dimensional vortices at the next impeller counterturn at higher Reynolds numbers. The fluctuation of each velocity component was remarkably small, suggesting that the flow field even at the highest Reynolds number was still laminar. It is found that effective transportation of energy from the impeller to 3-dimensional potential vortex is related to a large and constant power number, which is reported in our recent publication.
SOC CHEMICAL ENG JAPAN, 2016年04月, JOURNAL OF CHEMICAL ENGINEERING OF JAPAN, 49 (4), 341 - 349, 英語[査読有り]
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An experimental study has been performed in order to investigate the optimum rheological characteristics for a technique of heat transfer augmentation in a cavity between ribs mounted in parallel plates. The rheological characteristics of visco-elastic fluid were changed by controling the molar ratio of counter-ion to a cationic surfactant. Flow visualization experiments and pressure loss measurements were conducted in the range of solvent Reynolds number from 100 to 2,500 and in the range of molar ratio from 0.50 to 10. Under this condition, the zoro-shear Reynolds number and the Weissenberg number ranged from 2.01 to 120 and from 1.94 X 10(-2) to 9.15, respectively. From the results, flow penetration into the cavity occurred in the cases from 1.5 to 5.0 of molar ratio of counter-ions. However, the pressure loss became large in the cases when the remarkable Barns effect can be observed. On the other hand, the pressure loss became almost the same as that of water in the case when the molar ratio of counter-ions was set at 5.0. From this, it was concluded that the optimum fluid for the heat transfer augmentation in a cavity is required to have suitable elasticity and low viscosity as the molar ratio of counter-ions is set around 5.0.
SOC RHEOLOGY, JAPAN, 2016年, Nihon Reoroji Gakkaishi, 44 (3), 143 - 151, 英語[査読有り]
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In order to study the effects of extensional viscosities on turbulent drag reduction, experimental studies using two-dimensional turbulence have been made. Anisotropic structures and variations of energy transfer induced by polymers are considered. Polyethyleneoxide and hydroxypropyl cellulose having different flexibility are added to 2D turbulence. The different flexibility induces different characteristics of extensional viscosity. In addition, since increases of the extensional viscosity also depends on extensional rate, different extensional rate are added to the flow. Variations of the turbulence are visualized by interference patterns of 2D flow. The interference patterns are analyzed by 2D Fourier transform to detect effects of polymers in the streamwise and in the normal directions. Scaling exponent of power spectrum of the interference patterns indicate how energy transfer was changed by polymer additives. The energy transfer was also discussed by velocity field measured by PIV analysis. Wavelet transform are also applied to detect variations of characteristic scales in 2D turbulence.
SPRINGER, 2016年, Flow Turbulence and Combustion, 96 (1), 227 - 244, 英語[査読有り]
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A flow experiment of a dilute suspension and aggregation/dispersion analysis of fine particles in a non-uniform shear field were performed. We investigated the dispersion characteristics in a microchannel with an abrupt contraction section. The dispersed particles and dispersion media were polystyrene and aqueous glycerine, respectively. The particle diameter and solid volume fraction were 3.5 mu m and 0.001, respectively. Citric acid (0.5 and 1.0 wt%) was added as a non-ionic salt in order to investigate the effect of the aggregational force. The suspension was introduced into the microchannel with a syringe pump at a volume rate of 0.3 mu l-min(-1). The aggregation/dispersion characteristics of the fine particles were observed with a microscope and analyzed by image analysis. We observed the breakup and re-aggregational behavior of the fine particles in a dilute suspension. The cumulative frequencies of fine particles fluctuated through the channel. From the results, we posit the possibility that the non-uniformity of ions affect the aggregational characteristics of fine particles in a shear flow.
SOC RHEOLOGY, JAPAN, 2016年, Nihon Reoroji Gakkaishi, 44 (3), 153 - 158, 英語[査読有り]
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In order to investigate a fouling mechanism, adhesion behavior of a calcium carbonate particle onto various walls having different hydrophilic/hydrophobic characteristics have been studied. First, adhesion force was measured by atomic force microscope, which decreases with hydrophilicity of walls. Second, fouling phenomena on each plate was measured over time. In the case of the hydrophobic surface, bare copper plate, adhesive calcium carbonate crystal was increased, and the amounts reached the constant values. On the other hand, in the case of the hydrophilic surface, glass plate and hydrophilic coated copper, calcium carbonate crystal was adhered for several hours, then the crystal was removed from the plates. Crystal types of calcium carbonate on each plate were also analyzed by a X-ray diffractometer. The crystal type was varied due to the hydrophilic/hydrophobic characteristics of the plates. From the results, it was expected that the hydrophilic treatments to wall surfaces in heat exchanger might be useful to control fouling phenomena. (C) 2015 Elsevier Ltd. All rights reserved.
PERGAMON-ELSEVIER SCIENCE LTD, 2016年, International Journal of Heat and Mass Transfer, 92, 603 - 609, 英語[査読有り]
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The effect of the size of a combination structure of poly(vinyl alcohol) (PVA) as a stabilizer and drag-reducing surfactants in water on the sedimentation of particles of phase change materials (PCMs) in solutions was investigated. Behenyl trimethyl ammonium chloride was used as a surfactant with a 1.5 molar ratio of sodium salicylate as a counter-ion supplier at a constant surfactant concentration of 2,000 ppm in water, while the concentration of PVA was varied from 0 to 2,000 ppm. The structural size of the combined PVA and surfactant was measured with a dynamic light scattering (DLS) system. DLS analysis indicated that a large structure is formed by the interaction between PVA and surfactants. In addition, this structure becomes larger with the PVA concentration, and the occupation volume of the structure expands widely in a fluid. Thus, it was concluded that this large structure formation could cause an effective reduction of particle sedimentation in latent heat systems.
INT INST REFRIGERATION, 2016年, 11TH IIR CONFERENCE ON PHASE CHANGE MATERIALS AND SLURRIES FOR REFRIGERATION AND AIR CONDITIONING, 152 - 161, 英語[査読有り]
研究論文(国際会議プロシーディングス)
A novel fabrication technique of hard-shell microcapsules (HSMC) containing trimethylolethane hydrate as a phase change material has been tested with a double nozzle method. The inner and the outer diameters of the inner nozzle and the inner diameter of the outer nozzle of the double nozzle were fixed at 0.24, 0.46 and 0.8 mm, respectively. The inner/outer flow ratio was changed from 2.50 to 5.00, while the flow rate injected from the outer nozzle was kept constant at 2 ml/h. From the results, it was found that the mean diameter of capsules is 1.58 mm when the flow rate ratio is 2.50. In this case, a reasonable latent heat was also obtained. Thus, it was concluded that the present method for the fabrication of the capsules containing the trimethylolethane hydrate can be a promising method.
INT INST REFRIGERATION, 2016年, 11TH IIR CONFERENCE ON PHASE CHANGE MATERIALS AND SLURRIES FOR REFRIGERATION AND AIR CONDITIONING, 246 - 253, 英語[査読有り]
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Particle aggregates formed in a dispersing medium may be destroyed depending on the shear history applied in the coating process. Yielding behavior of gelled-clay particle dispersion can be interpreted as the destruction of particle network structure with the increase in shear strain. In the present study, gelled-clay particle dispersion was coated at different shear strain to control the initial status of particle aggregation of the drying process. The packing behavior of clay particles in the coated film was investigated from the viewpoint of void fraction in the film by the simultaneous measurements of weight loss and thickness decrease. Additionally, the change of surface roughness was researched based on the scattering pattern analysis. As a result, it was found that dispersed particles started to be packed tightly in the constant drying rate period, and that void fraction and surface structure of particle-packed layer scarcely changed in the latter part of the falling drying rate period. In contrast, if clay particle aggregates remained at the beginning of drying, a loosely packed particle layer was formed without changing surface structure in the constant drying rate period. However, the surface roughness was increased continuously in the falling drying rate period in spite of keeping constant film thickness, probably because void in the particle layer was collapsed.
Springer New York LLC, 2015年09月28日, Journal of Coatings Technology Research, 12 (5), 939 - 948, 英語[査読有り]
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A large plate impeller was rotated back and forth in a cylindrical vessel. Simultaneous and continuous measurements of the rotational torque on the mixing shaft and impeller angular position were carried out. The power consumption was computed by integrating the product of the measured torque and impeller rotational speed. The relationship between the power number and Reynolds number revealed that the Reynolds number became small for the transition in power characteristics and that the constant power number became large for the larger Reynolds number region at a small reciprocating amplitude with a large impeller acceleration. This is because a more remarkable startup flow was frequently repeated. The larger power number suggests that the rotationally reciprocating impeller has more efficient power characteristics compared to common rotational impellers. In terms of the torque variation, the measured torque was mainly dominated by the viscous force in the smaller Reynolds number region. As the Reynolds number increased, the phase lag between the torque and impeller speed increased even in the smaller Reynolds number region, and the measured torque was observed to fluctuate in the transition region. Although the measured torque was mainly dominated by the inertia force, the phase lag and magnitude of fluctuation did not increase any further at large Reynolds numbers.
SOC CHEMICAL ENG JAPAN, 2015年, Journal of Chemical Engineering of Japan, 48 (11), 885 - 890, 英語[査読有り]
研究論文(学術雑誌)
We have investigated the drying process of latex dispersion coating from the perspective of particle packing process. The behavior of particle aggregates in latex dispersions under shear flow was evaluated based on rheological measurement: particle aggregation under steady shear is related to apparent viscosities and time variation of elastic moduli shows reconstruction of aggregates. The effect of applied shear strain in coating on the thinning behavior of the latex dispersion coatings has been investigated. We found that the packing fraction of particles at the end of a constant film thinning rate period or concentration intricately changed with applied shear strain and glass transition temperature, T-g, of latex particle. If particles are completely dispersed, deformable particles having lower T-g are packed up to a maximum packing density, showing a very short falling drying rate period. In the case of insufficient shear strain application, however, aggregates formed a loosely packed layer, resulting in the emergence of a clearly decreasing thinning rate period. In contrast, hard spheres having the highest T-g formed a loosely packing particle layer similar to aggregated lower T-g particles.
SOC CHEMICAL ENG JAPAN, 2015年, Journal of Chemical Engineering of Japan, 48 (1), 87 - 93, 英語[査読有り]
研究論文(学術雑誌)
Cemented carbide is usually produced by sintering particles of metal carbides with binders. The non-aqueous suspension of both materials is spray-dried to produce granules having uniform material distribution, resulting in the excellent toughness of final products after sintering. Although the status of particle aggregation in a suspension should have a strong relationship with granule properties, the effect of surfactant on aggregative nature of particles has not been systematically investigated. In the present study, a new instrument was developed to measure apparent viscosity of metal particle suspension without sedimentation in order to investigate particle aggregation from the theological point of view. Additionally, the particle interaction has been quantitatively evaluated based on Usui's thixotropy model. It is found that the particle interaction was gradually reduced as increasing surfactant concentration, whereas granule properties changed only at higher concentrations. We also found the suspension stability and product functionality are balanced at the critical concentration. (C) 2014 Elsevier B.V. All rights reserved.
ELSEVIER SCIENCE BV, 2015年, Powder Technology, 271, 93 - 99, 英語[査読有り]
研究論文(学術雑誌)
Flow behaviors of sodium hyaluronate (HA-Na) in water solution and in phosphate buffered saline (PBS) solution as a viscoelastic fluids in planer abrupt contraction-expansion channels has been observed in this study. Especially, the effect of the geometry of the flow path on the flow behavior was focused on. The corner vortices in the corner of the upper region in the abrupt contraction-expansion channels were also analyzed to quantify the flow characteristics. The elasticity numbers of the solution, which is affected by rheological properties of the solution and the channel geometry had a big influence on the fluidity, that is, stable or unstable, when the concentration of the solution in lower. It was concluded that such stable and unstable flows are categorized on Wissenberg-Reynolds number space.
American Society of Mechanical Engineers, 2015年, ASME/JSME/KSME 2015 Joint Fluids Engineering Conference, AJKFluids 2015, 2A, 7pages, 英語[査読有り]
研究論文(国際会議プロシーディングス)
Two-dimensional numerical computations of unsteady flow of a suspension between two coaxial cylinders are performed. We investigate the dispersion characteristics based on a novel thixotropy model. The diameter of particles, solid volume fraction, and viscosity of dispersing media are set to 2.5 mu m, 0.15, and 195 Pa.s, respectively. The shear rate is suddenly changed from 0.1 s(-1) to 1 s(-1). For model validation, the numerical results are compared with previously reported experimental results. The mean number of particles in a cluster increases slightly shortly after the shear rate change, reaches a maximum, and subsequently decreases, finally attaining a steady state at 40 s after the shear rate change. Our model better expresses the time variation of the dispersion characteristics than the previous model. After the validation, the effect of bonding energy on the time-variation characteristics is investigated. The bonding energy is varied as 2.7 x 10(-13), 2.7 x 10(-12), and 2.7x10(-11) J. We observe that the asymptotic values of the mean number of particles in a cluster depend on the bonding energy, but this relationship is not linear. From our results, we posit the existence of a certain critical bonding energy with regard to the dispersion characteristics.
SOC RHEOLOGY, JAPAN, 2015年, Nihon Reoroji Gakkaishi, 43 (3-4), 85 - 92, 英語[査読有り]
研究論文(学術雑誌)
Flow characteristics of visco-elastic fluids sweeping a one-side micro-cavity mounted in a micro-duct have been investigated in order to develop a novel technique of a mixing process for micro-reactors. In this paper, effects of the Reynolds number and of the rheological characteristics of the fluids were focused on. The cavity depth, the cavity length and the width of the wider flow path were fixed at 200, 1,000 and 400 gm, respectively. As a visco-elastic fluid, a solution of cationic surfactants with counter-ions was used. The molar ratio of counter-ions to surfactants was changed in four steps in order to change the rheological characteristics of the visco-elastic fluids. The Reynolds number was also changed from 0.100 to 100. From the results, it was found that a tonguing motion of the separation fluid bubble tip formed in the downstream region in the cavity occurs at a certain Weissenberg number larger than 200 due to the elastic instability. The fluctuating bulge structure was also observed on the upstream side wall of the cavity in a higher range of the Weissenberg number. Such a elastic instability can be expected a suitable micro-fluid motion for the micro-mixing. (C) 2015 Elsevier Inc. All rights reserved.
ELSEVIER SCIENCE INC, 2015年, Experimental Thermal and Fluid Science, 67, 96 - 101, 英語[査読有り]
研究論文(学術雑誌)
研究論文(その他学術会議資料等)
研究論文(国際会議プロシーディングス)
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An experimental study has been performed in order to investigate the relationship between the extensional viscosity of polymer solution and the turbulent drag reduction. A flexible polymer and a rigid rod-like polymer were added to the two-dimensional turbulent flow that was visualized by the interference pattern of a flowing soap film and analyzed by a single-image analysis. The power spectra of interference images were obtained, which is related to the water layer fluctuations in turbulence. The power spectra show a scaling behavior and the power components give the information of drag reduction. It was suggested that the energy transfer mechanisms are different in streamwise and normal directions. In the normal direction, the energy transfer was prohibited by the orientation of polymers, while the energy transfer in the streamwise direction was prohibited by extensional viscosity of polymers. The extensional viscosities of polymer solutions were measured by calculating pressure losses at an abrupt contraction flow.
Springer-Verlag Wien, 2014年01月01日, Mechanics and Model-Based Control of Advanced Engineering Systems, 163 - 170, 英語[査読有り]
論文集(書籍)内論文
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研究論文(学術雑誌)
Aluminum ammonium sulfate dodecahydrate (ammonium alum hydrate) slurries are promising latent heat media for high temperature applications. However, a major problem associated with materials developed specifically for high temperature use is sedimentation in the pipes of the device. Thus, the ability of poly vinyl alcohol (PVA) to prevent sedimentation and particle growth of ammonium alum hydrates has been investigated in this study. In order to increase the fluidity of the slurry, a cationic surfactant, behenyl trimethyl ammonium chloride, was used as a drag-reducing agent, and the interaction between the cationic surfactant and PVA was evaluated. The rheological properties of the slurries and solutions were investigated, and they indicated that the drag-reducing cationic surfactant was not disturbed by the PVA.
SOC CHEMICAL ENG JAPAN, 2014年, JOURNAL OF CHEMICAL ENGINEERING OF JAPAN, 47 (2), 169 - 174, 英語研究論文(学術雑誌)
Aluminum ammonium sulfate dodecahydrate (ammonium alum hydrate) slurries are promising latent heat media for high temperature applications. However, a major problem associated with materials developed specifically for high temperature use is sedimentation in the pipes of the device. Thus, the ability of poly vinyl alcohol (PVA) to prevent sedimentation and particle growth of ammonium alum hydrates has been investigated in this study. In order to increase the fluidity of the slurry, a cationic surfactant, behenyl trimethyl ammonium chloride, was used as a drag-reducing agent, and the interaction between the cationic surfactant and PVA was evaluated. The rheological properties of the slurries and solutions were investigated, and they indicated that the drag-reducing cationic surfactant was not disturbed by the PVA.
SOC CHEMICAL ENG JAPAN, 2014年, Journal of Chemical Engineering of Japan, 47 (2), 169 - 174, 英語[査読有り]
研究論文(学術雑誌)
This study deals with fluid mixing process in the circular cross-section of a cylindrical vessel using a rotationally reciprocating (back and forth rotation) plate impeller from the view point of experimental visualization and numerical simulation. We have investigated the fluid deformation process with the visualization of streak lines. It has been found that a pair of vortices generated at the impeller tip plays a crucial role in stretching and folding of streak lines. Additionally, for effective overall mixing, we found that fluid needs to be dragged inward to the region near the mixing shaft, stretched and folded along the impeller plate, and then extensively deformed from the impeller tip. However, since the path of fluid inward motion is rarely disturbed by locally strong vortices generated at the conditions of small amplitude and short period, a poor mixing region expanded from the mixing shaft to the vessel wall, which made two separated mixing regions in a vessel. With increasing amplitude, the poor mixing region shrunk near the mixing shaft. In the case of the largest amplitude and longest period, fluid was effectively deformed everywhere in the vessel, which leads to a highly intensified mixing process.
SOC CHEMICAL ENG JAPAN, 2014年, Journal of Chemical Engineering of Japan, 47 (2), 151 - 158, 英語[査読有り]
研究論文(学術雑誌)
The characteristics of oxygen dissolution accelerated by the use of micro-bubbles in a viscoelastic fluid were studied. An aqueous solution of a combination of a cationic surfactant and of a counter-ion supplier was used as a viscoelastic fluid. Flow visualizations and measurements on the time variation of the oxygen concentration were performed. From the results, it was found that the dissolution of oxygen rapidly occurs by the use of microbubbles, but the dissolution becomes slow in a highly elastic fluid. The flow observation of bubbles in a highly elastic fluid showed a chaining effect with bubble ascension. Bubble chaining was found to accelerate the agglomeration of bubbles and decrease the apparent gas-liquid interface area. Thus, such a chaining effect was concluded to disturb the dissolution of oxygen.
SOC CHEMICAL ENG JAPAN, 2014年, Journal of Chemical Engineering of Japan, 47 (2), 201 - 206, 英語[査読有り]
研究論文(学術雑誌)
A fabrication process via the double-emulsion method is proposed for silica hard-shell microcapsules (HSMCs) that contain trimethylolethane (TME) hydrate. The TME-encapsulating silica-HSMCs are promising materials for reusable phase-change materials for latent-heat transportation systems. The obtained silica-HSMCs were visualized by a scanning electron microscope. The amount of TME hydrate inside the capsules was confirmed using a differential scanning calorimeter. The measured latent heat of the TME-encapsulating silica-HSMC was a reasonable fit to the predicted value.
CHEMICAL SOC JAPAN, 2014年, Chemistry Letters, 43 (6), 820 - 821, 英語[査読有り]
研究論文(学術雑誌)
Aluminum ammonium sulfate dodecahydrate (ammonium alum hydrate) slurry is a promising latent heat medium for high-temperature systems. However, there exist the significant issues with this medium at high temperature with respect to crystal agglomeration, growth, and sedimentation. Therefore, the effects of adding drag-reducing surfactants and poly vinyl alcohol (PVA) on the formation process of ammonium alum hydrates crystals under a controlled shear flow have been investigated in this study. In addition, in order to investigate the impact of the surface hydrophilicity and hydrophobicity of cooling walls on the crystal growth, a copper plate and a silica coated copper plate were used as the substrates of the wall. From the results, it was found that the mean crystal size of the ammonium alum hydrate decreased with increasing shear rates and with the addition of surfactants and PVA. In addition, the crystals on the silica coated copper plate were smaller than those on the copper plate without a coating. Thus, the addition of drag-reducing surfactants and PVA and use of a hydrophilic surface prevented the crystal agglomeration and crysal growth of the ammonium alum hydrate under a shear flow. Furthermore, the viscosity of each solution was also measured, as affected by the various additives and by crystal agglomeration and growth.
SOC RHEOLOGY, JAPAN, 2014年, Nihon Reoroji Gakkaishi, 42 (4), 219 - 226, 英語[査読有り]
研究論文(学術雑誌)
An experimental study has been performed to investigate the relationship between the extensional viscosity of polymers and the turbulent drag reduction. Self-standing flowing soap film was used to generate two-dimensional (2-D) turbulent flow to eliminate shear stress. Two types of polymers having different flexibilities were added to the 2-D turbulence. The effects of these polymers were visualized by the interference pattern of flowing soap films. The vortex deformation by adding polymers was analyzed by Fourier transformation and wavelet transformation. The scaling exponents of the power spectrum of interference patterns indicate that the mechanism of turbulence laminarization due to the extensional viscosity is anisotropic. A wavelet analysis reveals the high and low fluctuations of the polymer-added flow. Results from wavelet analysis indicate disappearing of original vortices, and appearing of new structures in low frequency in 2-D flow. (c) 2014 American Institute of Chemical Engineers AIChE J, 60: 1854-1862, 2014
WILEY-BLACKWELL, 2014年, Aiche Journal, 60 (5), 1854 - 1862, 英語[査読有り]
研究論文(学術雑誌)
In order to study a bulge structure observed in a cavity swept by a viscoelastic fluid, flow visualization experiments have been performed. The cavity depth, the cavity length and the width of flow path were fixed while the water Reynolds number based on the narrow flow path was changed from 680 to 4,200. From the results, the bulge structure formed on the upstream backward-facing side wall of the cavity in the mid-range of the Reynolds number was found to lead a fresh fluid into a cavity and to sweep the fluid near the cavity bottom wall. The bulge structure fluctuates very slowly and this fluctuation induces a tonguing motion of the tip of the separation bubble formed in the downstream region of the cavity. Thus, this structure can be expected to enhance the heat transfer from the cavity bottom.
IOP PUBLISHING LTD, 2014年, Xxi Fluid Mechanics Conference, 530, 01255 - 01262, 英語[査読有り]
研究論文(学術雑誌)
A fabrication process via the double-emulsion method is proposed for silica hard-shell microcapsules (HSMCs) that contain trimethylolethane (TME) hydrate. The TME-encapsulating silica-HSMCs are promising materials for reusable phasechange materials for latent-heat transportation systems. The obtained silica-HSMCs were visualized by a scanning electron microscope. The amount of TME hydrate inside the capsules was confirmed using a differential scanning calorimeter. The measured latent heat of the TME-encapsulating silica-HSMC was a reasonable fit to the predicted value. © 2014 The Chemical Society of Japan.
Chemical Society of Japan, 2014年, Chemistry Letters, 43 (6), 820 - 821, 英語[査読有り]
研究論文(学術雑誌)
研究論文(国際会議プロシーディングス)
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研究論文(国際会議プロシーディングス)
The 10th IIR Conference on Phase-Change Materials and Slurries for Refrigeration and Air Conditioning was held from 29th July to 2nd August 2012 in Kobe, Japan. Emulsion systems of organic phase-change materials such as tetradecane were reported during the conference. Prof. Arydi Suwono discussed trimethylolethane (TME) hydrate systems in his keynote lecture. The flow and heat transfer characteristics of phase-change material slurries were also discussed during the conference. During this conference, several researchers reported novel techniques using nanoparticles and carbon nanotubes in order to enable thermal conductivity improvements of phase change materials. Several authors also reported improvements in the wall in a generator of phase-change materials with nano-composites and with some chemical materials.
2013年09月, International Journal of Refrigeration, 36 (6), 1790 - 1791, 英語[査読有り]
研究論文(国際会議プロシーディングス)
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Experimental studies have been conducted in order to obtain information on thermophysical properties and reaction characteristics of composite reactant of calcium chloride and expanded graphite, which has been developed to improve the performance of a reactor bed used for gas solid chemical heat pumps. Effective thermal conductivity, permeability and reaction rate of the composite reactant have been measured. From the results of heat transfer experiments it was found that the effective thermal conductivity of the composite reactant is more than ten times larger than granular calcium chloride and strongly affected by void fraction. Permeability measurements show that the Darcy number increases rapidly with decreasing void fraction in the range of the void fraction from 0.4 to 0.6. The rate of reaction of composite reactant with water has been measured using a small cell which simulates a part of reactor bed where the reactant is packed between fins of plate-fin heat exchanger. The measured overall reaction rate has been analyzed using a model which is developed by taking account of the influence of adsorption of water molecules on hydration rate. (C) 2011 Elsevier Ltd. All rights reserved.
PERGAMON-ELSEVIER SCIENCE LTD, 2013年, Applied Thermal Engineering, 50 (2), 1627 - 1632, 英語[査読有り]
研究論文(学術雑誌)
A model estimating local particle dispersion/aggregation behaviors in a suspension has been developed for a nonuniform shear flow. In this model, the size distributions of particle clusters were calculated with taking a balance of Brownian and shear coagulationsand shear breakup. A numerical simulation was performed for a two-dimensional backward-step flow as a non-uniform shear flow. A flow experiment using a micro-channel with a rib was also conducted for the verification of the present numerical analysis. The solid volume fraction of the suspension was set at 0.01 and the step height Reynolds number was keptconstant at 1.5×10-4 both for numerical and for experimental studies. The numerical results obtained in this study were rather reasonable compared with the experimental data. From this, it was found that the present numerical model is promising for estimating particle dispersion/aggregation in a non-uniform shear flow. © 2013 The Society of Rheology, Japan.
2013年, Nihon Reoroji Gakkaishi, 41 (2), 75 - 81, 英語[査読有り]
研究論文(学術雑誌)
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An experimental study has been performed to investigate the relationship between the extensional viscosity of polymers and the turbulent drag reduction. In order to obtain the flow which is mostly dominated by extensional flow, two-dimensional (2D) grid turbulence made by flowing soap films was used. Extensional rate added to the flow was controlled by changing the conformation of the grid. Polyethylene oxide, as a flexible polymer, and hydroxypropyl cellulose, as a rigid rod-like polymer were added to the flow. Several extensional rates affect polymer behaviors, which induce different effects. Drag reduction effects of polymers under several extensional rates were visualized and analyzed by image processing. Rheological properties of the polymer solutions were also measured by a rheometer. The results indicated that the mechanisms of energy transfer are different in the streamwise and normal directions. The critical concentration to observe drag reduction effects in 2D turbulence was changed by the extensional rate. When extensional rate is higher, the effects were started to observe from lower concentration. These results were confirmed to correspond to the drag reduction effects obtained by classical pressure drop experiments in a pipe flow.
SPRINGER, 2013年, Rheologica Acta, 52 (10-12), 949 - 961, 英語[査読有り]
研究論文(学術雑誌)
In this paper, aggregation/dispersion behaviors of particle clusters in a non-uniform shear flow have been numerically analyzed using a thixotropy model for estimating local cluster size distributions. The effects of the viscosity of the dispersion media, the solid volume fraction and the Reynolds number on the cluster size distribution in a two-dimensional flow between parallel plates were investigated in order to find the primary factor determining the cluster size distributions. The viscosity of the dispersed media, the solid fraction and the Reynolds number were changed from 195 to 1950 Pa.s, from 0.10 to 0.25 and from 0.1 to 1.0, respectively. From the results, it is found for each case that large clusters are observed at the central area of the channel, but it becomes smaller near the wall where high shear is added. The cluster size near the wall is dominated by the shear stress. On the other hand, it is found that the cross-sectional averaged cluster size depends on the bulk velocity under the present conditions. As the cluster size near the wall can be correlated rather well with the bulk velocity, it is concluded that the bulk velocity is a convenient and useful factor for the dispersion/aggregation behaviors of fine particles under the present conditions.
SOC CHEMICAL ENG JAPAN, 2013年, Journal of Chemical Engineering of Japan, 46 (8), 524 - 529, 英語[査読有り]
研究論文(学術雑誌)
Flow and heat transfer characteristics of ammonium alum hydrate slurries have been investigated. Ammonium alum hydrate has high latent heat of 251 kJ kg(-1) and its melting temperature is 51 degrees C when the concentration of ammonium alum in water was set at 35 wt %. The friction and the melting heat transfer coefficients were measured in a pipe flow with 13 mm of diameter. From the results, it was found that the friction coefficient of ammonium alum hydrate slurry shows almost the same value as that of water. On the other hand, the slurry shows higher heat transfer than that of water. Especially, the heat transfer enhanced rate becomes high when the temperature difference between the slurry and the heating flow was set small. This is because of the temperature sustainability of phase change material slurries. From this, it was concluded that ammonium alum hydrate slurry can be a promising candidate for a heating system. (C) 2012 Elsevier Ltd and IIR. All rights reserved.
ELSEVIER SCI LTD, 2013年, International Journal of Refrigeration-Revue Internationale Du Froid, 36 (1), 81 - 87, 英語[査読有り]
研究論文(学術雑誌)
Polymer solution shows complex behaviors, which are merits and demerits in industries. For a molding process, a fiber spinning process and a turbulent drag reduction system, concentrated or dilute polymer solutions are used. In these processes, characteristics of extensional viscosity should be important. For example, increments of extensional viscosities due to polymers are considered as one of the reasons for the drag reduction occurrence. In this study, we propose a simple technique to measure the extensional viscosity of Newtonian and non-Newtonian fluids in abrupt contraction flows. The abrupt contraction flow was realized by connecting a syringe and a thin glass tube under a polarizing microscope. The syringe was filled with Newtonian and non-Newtonian fluids, and a syringe driver control to push the fluids out. The force to push the syringe was measured by a load cell to calculate the pressure added to the flow. Extensional viscosity was calculated by considering the pressure losses in the abrupt contraction flows. Water was measured as a Newtonian fluid, and polymer solution was measured as a non-Newtonian fluid. Extensional viscosity of the polymer solution measured in this study qualitatively shows the reasonable characteristics. © 2013 The Japan Society of Mechanical Engineers.
2013年, Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B, 79 (803), 1264 - 1268, 日本語研究論文(学術雑誌)
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Dispersion and agglomeration of particles with a drastic change in fluid flow differs from those under a steady shear flow. In this study, the development and destruction of particle agglomerates with step-wise shear rate change were investigated by microscopic observation, and the results were compared with particle dispersibility predicted from rheological data. Polystyrene particles with strong agglomerative properties could be controlled by addition of small amount of carboxymethylcellulose (CMC). Once the particles were sufficiently dispersed, the agglomeration process was dominated by the collision of particles and was not affected by polymer concentration. When the amount of adsorbed CMC was sufficient to prevent the aggregation of particles, agglomerates readily dispersed to an agglomerative state corresponding to the applied shear rate. However, insufficient adsorption of CMC resulted in a heterogeneous agglomeration process that took longer time to attain steady agglomerated state. Slurry viscosity was employed to evaluate agglomerative nature except under conditions of complete dispersion.
SOC CHEMICAL ENG JAPAN, 2012年, 化学工学論文集, 38 (1), 13 - 18, 日本語[査読有り]
研究論文(学術雑誌)
Aqueous solutions of some kinds of surfactants and counterions are known as viscoelastic fluids. The rheological properties and fluidity of the solutions are significantly affected by the surfactant and counterion concentrations. Thus, the solution is a potential solvent for industrial applications because a drastic change in the fluidity can be realized only through the addition of counterions. In this study, we focused on the characteristics of the fluid flow of viscoelastic surfactant solutions in a mixing vessel. It was found that in the vicinity of the impeller the fluid was actively mixed and contained a large number of laminated fluid lumps, forming onion-like structure. When the elastic force becomes comparable to the viscous force, the micellar network of the surfactant was deformed. Additionally, if the elastic force was not much smaller than the inertia force, the impeller region was covered by a network-deformed fluid and an onion-like structure was then formed. Moreover, a stable onion-like structure was obtained when the impeller rotated as slowly as possible or when the elastic force of the solution was more significant than the viscous one.
SOC CHEMICAL ENG JAPAN, 2012年, Journal of Chemical Engineering of Japan, 45 (2), 94 - 101, 英語[査読有り]
研究論文(学術雑誌)
The flow and heat transfer characteristics of an ammonium alum hydrate slurry treated with drag-reducing surfactants have been investigated experimentally. Ammonium alum hydrate has a high latent heat of 251 kJ/kg, and its fusion temperature is 51 degrees C when the concentration of ammonium alum in water is 35 wt%. The friction coefficient and the heat transfer coefficient for melting were measured from a pipe flow with a diameter of 13 mm. From the results, it was found that the ammonium alum hydrate slurry treated with surfactants shows the effective drag reduction in a pipe flow. It was also found that the heat transfer of the slurry with the surfactants is reduced slightly; in particular, this was true in the case of a high temperature difference between the slurry and heating water flowing outside a test tube. However, the heat transfer coefficient of the slurry with surfactants divided by pressure loss was very high, and particle growth due to particle agglomeration could be reduced by the surfactants. From this, it was concluded that the ammonia alum hydrate slurry with the surfactant is a promising system as a heat transportation medium.
SOC CHEMICAL ENG JAPAN, 2012年, Journal of Chemical Engineering of Japan, 45 (2), 136 - 141, 英語[査読有り]
研究論文(学術雑誌)
In order to develop turbulent drag-reducing technology by using an environmentally friendly additive in a water-transporting system, the drag reducing characteristics in a non-ionic surfactant (Oleyldimethylamineoxide, ODMAO) dilute aqueous solution flowing in a circular pipe of 5 mm diameter have been experimentally investigated with an air-driven fluid resistance test device. The rheological characteristics of the solution have also been examined by a rheometer with a cone-plate flow cell. The results show that the ODMAO solutions are drag-reducing when concentration is 400 ppm or higher, that the critical Reynolds number corresponding to the maximum drag reduction rate increases with both concentration and temperature, and that the maximum drag reduction rate can reach up to 70% in the straight pipe. At low shear rates, the shear viscosity of ODMAO solutions with a relatively high drag-reduction behaves similarly to Newtonian fluids; at above a certain critical shear rate, it is firstly shear-thickening, then shear-thinning. Such shear-rate-dependent characteristics of the shear viscosity are attributed to the different transitions of micellar network structure induced by different shear rates. Relaxation of shear stress after removing an applied constant shear rate at which the solution is in the SIS (shear-induced structure) state is found to be well expressed by a 2-step Maxwell model with a tail relaxation time much shorter than that for a drag-reducing cationic surfactant, which indicates that for the ODMAO solution, a viscoelasticity as strong as a drag-reducing cationic surfactant is not needed to realize turbulent drag-reduction.
SCIENCE PRESS, 2012年, Science China-Technological Sciences, 55 (3), 772 - 778, 英語[査読有り]
研究論文(学術雑誌)
Experimental study on the relaxation behavior of the drag-reducing surfactant solution has been performed in order to investigate the mechanism of the drag reduction occurrence. The relaxation times and the drag reduction rates were measured in a wide range of the surfactant concentration and of the molar ratio of the counter-ions to surfactants. From the results, it was found that the present surfactant solution has at most three relaxation times in a middle range of the surfactant concentration and of the molar ratio. It was also found that the drag reduction occurs when the shortest relaxation time of 0.1 s exists. Thus, it was concluded that the existence of the shear-induced structure having this shortest relaxation time is important for the drag reduction occurrence.
SOC RHEOLOGY, JAPAN, 2012年, Nihon Reoroji Gakkaishi, 40 (2), 85 - 90, 英語[査読有り]
研究論文(学術雑誌)
[査読有り]
研究論文(学術雑誌)
An understanding of the conversion process from slurry to particle layer on a substrate is required for the precise control of the particle alignment and the material distribution in the coated slurry. In this work, variation of coated slurry thickness during drying was applied to evaluate drying and particle layer formation simultaneously. The slurry used consisted of micron-sized silica or poly (methyl methacrylate) particles and an aqueous solution of poly-vinyl alcohol (PVA) possessing differing degrees of hydrolysis. During the drying process, initially the thickness of the coated slurry was observed to decrease at a constant rate in the concentration stage, and subsequently it began to show large fluctuations due to the emergence of particles on the drying surface in the packing stage. In the final fixing stage, the fluctuation of film thickness was restricted because particles were immobilized by highly viscous concentrated PVA or by PVA molecule bridging. Based on the variation and fluctuation of film thickness, we introduced two characteristic dimensionless time ratios: (a) void fraction in a packed particle layer at the end of concentration stage; and (b) the time required to fix particle position after the end of the packing stage. We concluded that the dispersed state and settling velocity of the particle determines the space between particles in a loose packing layer, and we found that the distribution of polymers in a particle layer has a strong influence on the mobility of particles in a tightly packed layer.
TAYLOR & FRANCIS INC, 2011年, Drying Technology, 29 (9), 1037 - 1045, 英語[査読有り]
研究論文(学術雑誌)
[査読有り]
研究論文(学術雑誌)
Two-dimensional numerical computations have been performed in order to investigate the development characteristics of flow and thermal field in a flow between parallel plates swept by a visco-elastic fluid. In the present study, the effect of the cavity number in the domain and of Reynolds number was focused on when the geometric parameters were set constant. From the results, it is found that the flow penetration into the cavities effectively causes the heat transfer augmentation in the cavities in any cavity region compared with that of water case. It is also found that the development of thermal field in cases of the present visco-elastic fluid is quicker compared with that of water cases. The present heat transfer augmentation technique using Barus effect of a visco-elastic fluid is effective in the range of low Reynolds number.
AMER SOC MECHANICAL ENGINEERS, 2010年, Proceedings of the Asme International Heat Transfer Conference - 2010, Vol 2, 635 - 641, 英語[査読有り]
研究論文(学術雑誌)
Various thin films are produced by coating and drying of slurries. Cracks and fractures in the film, which frequently are encountered under a large drying rate condition, can be avoided by a reduction in drying rate. In this work, we propose a novel drying technique (pressure controlled drying), where the coated slurry is dried in a container filled with vapor of the drying solvent. If the inner pressure of the container is held reasonably higher than the saturation vapor pressure of the solvent, the drying rate can be successfully depressed. It was also turned out that the residual amount of the solvent in the coated slurry before and after holding the pressure has to be carefully controlled in order to work this drying technique effectively. The residual solvent is affected mainly not only by the time of holding the pressure but also by the container volume, decompressing capacity, and co-drying solvent. When the drying rate could be suppressed till the end of the constant drying rate period, the resultant film had a tightly packed cellular pattern and a smooth surface. This is probably due to the enhancement of particle arrangement with sufficient amount of the solvent and long drying time.
SOC CHEMICAL ENG JAPAN, 2010年, Journal of Chemical Engineering of Japan, 43 (10), 892 - 900, 英語[査読有り]
研究論文(学術雑誌)
In order to investigate the optimum geometric conditions for a heat transfer augmentation technique using visco-elastic fluid, flow visualization experiments have been performed in a cavity between rectangular ribs. The rib height, the rib length and the cavity size were changed in several steps while the mean velocity at narrow cross-sections was kept constant. From the results, it is expected that the case having small rib height, small rib length and large cavity size has an advantage for heat transfer augmentation. It is also found that the recirculation size is a simple function of contraction ratio and Weissenberg number.
SOC CHEMICAL ENG JAPAN, 2010年, JOURNAL OF CHEMICAL ENGINEERING OF JAPAN, 43 (5), 421 - 428, 英語[査読有り]
研究論文(学術雑誌)
Experimental studies on flow characteristics and particle size distributions of trimethylolethane (TME) hydrate slurries treated with drag-reducing surfactants have been conducted to investigate the effect of the molar ratio of counter-ions to surfactants. Oleylbishydroxyethylmethylammonium chloride is used as the drag-reducing surfactants. The molar ratio of sodium salicylate supplying counter-ions to surfactants is adjusted from 0 to 100 while the concentrations of TME in water and of surfactants remains constant at 25 wt% and at 2000 ppm, respectively. Results unexpectedly indicate that the drag reduction is greatest when the molar ratio of the counter-ions to surfactants is 20 against the fact that the higher molar ratio shows the higher drag reduction in water case. This indicates that some interaction between the counter-ions and TME molecules occurs and that it disturbs the formation of rod-like micellar structures causing the drag reduction. Thus, a molar ratio of counter-ions to surfactants of 20 is concluded to be the optimum for the drag reduction although it has a detrimental effect on the particle size under the present experimental conditions used.
SOC CHEMICAL ENG JAPAN, 2010年, Journal of Chemical Engineering of Japan, 43 (4), 349 - 354, 英語[査読有り]
研究論文(学術雑誌)
An experimental study on flow characteristics of trimethylolethane (TME) hydrate slurries treated with drag-reducing surfactants has been performed in order to investigate the effect of molar ratio of counter-ions to surfactants. As drag-reducing surfactants, oleylbishydroxyethylmethylammonium chloride was used. The molar ratio of counter-ions of sodium salicylate to surfactants ranged from 0 to 100 and surfactant concentration was changed in two steps; 1000 ppm and 2.000 ppm while the concentration of TME in water was set constant at 25 wt%. From the results, it was found that the drag reduction limitation becomes larger when the molar ratio of the counter-ions to surfactants is set around 20 for each surfactant concentration. From the detailed discussions, the drag reduction characteristics in a higher range of the molar ratio of counter-ions to surfactants were found to relate to the molar ratio of counter-ions to TME more significantly. Under the present conditions, it was concluded that 0.05 of the molar ratio of counter-ions to TME shows the most effective drag reduction. (C) 2010 Elsevier Ltd and IIR. All rights reserved.
ELSEVIER SCI LTD, 2010年, International Journal of Refrigeration-Revue Internationale Du Froid, 33 (8), 1632 - 1638, 英語[査読有り]
研究論文(学術雑誌)
The thermal characteristics of inorganic disodium hydrogen phosphate dodecahydrate (Na2HPO4 center dot 12H(2)O) slurries in a water/ethylene glycol mixture were investigated in an attempt to reduce the size of absorbers in absorption chillers. In order to find the optimal concentration of Na2HPO4 center dot 12H(2)O and the optimal weight ratio of ethylene glycol to the mixture for cooling the absorber, solubility, phase change temperature, and latent heat were measured. The obtained results indicated that the hydrate slurry has an appropriate phase change temperature and sufficient concentration at the working temperature of the absorber when the hydrate concentration and the weight ratio of ethylene glycol to the mixture are set to 50 wt% and 0.4, respectively. Under this condition, the particle characteristics of the slurries were also measured. The particle size was found to be rather small, and it increased gradually. Thus, inorganic Na2HPO4 center dot 12H(2)O can be used as a cooling medium of the absorber in an absorption chiller.
SOC CHEMICAL ENG JAPAN, 2010年, Journal of Chemical Engineering of Japan, 43 (1), 34 - 39, 英語[査読有り]
研究論文(学術雑誌)
Slurry containing hydrate particles as a phase-change material in the aqueous surfactant solution with counter-ion can be applied to construct a highly effective heat transport system by the combination of latent heat and drag-reducing effect. However, the efficiency of the system is influenced not only by thermal characteristics but also by the fluidity of the slurry, which is influenced by the size and concentration of the particles and the agglomerates. In this study, we first investigate the condition providing steady crystallized slurry. It has been found that crystallization attained steady state within 1 hour after the start of crystallization under a well-agitated condition. The viscosities and first normal stress differences of the steady crystallized slurry and saturated solution were measured to clarify the interaction between hydrate particle and micellar structure of surfactant. As a result, it turned out that the agglomeration of the hydrate particles was influenced by the size and strength of the micellar structure depends on the concentration of counter-ion. In particular, a slurry containing a large amount of counter-ion showed a drastic decrease in fluidity in a certain shear rate range probably due to agglomeration of entangled structures of surfactants.
SOC CHEMICAL ENG JAPAN, 2010年, Journal of Chemical Engineering of Japan, 43 (1), 23 - 28, 英語[査読有り]
研究論文(学術雑誌)
Ice growth depression and drag reduction of ice slurries treated with a combination additive of cetyl dimethyl betaine (surfactant) and poly(vinyl alcohol) (PVA) have been investigated. From the results, it is found that the particle size becomes smaller when treated by the present surfactants compared with the corresponding result of each concentration of PVA. Additionally, particle growth depression can be observed due to a cooperative effect of surfactants, even in the case when PVA concentration was reduced to 4 g/l from 8.7 g/l, which was required in the case without surfactants. The present combination additives also cause drag reduction phenomena on the solution. Thus, the combination of surfactants and of PVA could be a promising candidate as additives for improvement of ice slurry fluidity.
SOC CHEMICAL ENG JAPAN, 2010年, JOURNAL OF CHEMICAL ENGINEERING OF JAPAN, 43 (6), 482 - 486, 英語[査読有り]
研究論文(学術雑誌)
Numerical computations on vapor flow and non-absorbable gas diffusion in the evaporator/absorber are performed in order to research the extraction method of non-absorbable gas. Non-absorbable gas behavior was tried to control by using an immersed plate and an extraction. From the results, it was found that both the immersed plate and the extraction can prevent from the performance decrease of the absorber. Non-absorbable gas tended to stay in the low vapor velocity region, because non-absorbable gas is rolled up into the low velocity region. Non-absorbable gas diffused from the low velocity region, when the vapor velocity entirely becomes lower because of the absorber performance decreases. In order to extract non-absorbable gas effectively, the extraction vent should be mounted near the position where non-absorbable gas was concentrated.
SOC CHEMICAL ENG JAPAN, 2010年, JOURNAL OF CHEMICAL ENGINEERING OF JAPAN, 43 (7), 561 - 568, 英語[査読有り]
研究論文(学術雑誌)
研究論文(国際会議プロシーディングス)
A heat transfer model of the evaporator in an absorption chiller was developed by modification of Nusselt's film theory. This liquid film model was found to agree with existing experimental correlations in the film Reynolds number region in which the tube is assumed to be fully wetted. Next, two-dimensional numerical computations of vapor flow in the evaporator/absorber were performed with boundary conditions of the evaporator and the absorber respectively derived from each liquid film model. The results showed that the velocity distribution around the evaporator and the velocity field between the evaporator and the absorber are different from those when the vapor evaporates uniformly on the surface of the cylinders in the evaporator.
SOC CHEMICAL ENG JAPAN, 2009年09月, KAGAKU KOGAKU RONBUNSHU, 35 (5), 417 - 424, 日本語[査読有り]
研究論文(学術雑誌)
[査読有り]
研究論文(学術雑誌)
Drag reduction characteristics of trimethylolethane hydrate slurries treated with surfactants have been investigated. The effects of the surfactant concentration and hydrate fraction of the slurry on drag reduction behaviors were focused on in this paper. The friction coefficient in a pipe flow of hydrate slurries treated with surfactants and the relaxation time of trimethylolethane solution with surfactants were measured. From the results, it was found that the effective drag reduction appears in the cases of high surfactant concentration even in cases of high hydrate fraction. This behavior was supported by the viscosity shear-thickening occurrence reported in the previous study. However, the effective drag reduction disappears in the cases of low surfactant concentration in spite of the shear-thickening occurrence. On this discrepancy, the relaxation time of the solution was measured. It is found that the critical concentration determined from the relaxation time disappearance well corresponds to the limitation of effective drag reduction occurrence. (C) 2008 Elsevier Ltd and IIR. All rights reserved.
ELSEVIER SCI LTD, 2009年08月, INTERNATIONAL JOURNAL OF REFRIGERATION-REVUE INTERNATIONALE DU FROID, 32 (5), 931 - 937, 英語[査読有り]
研究論文(学術雑誌)
研究論文(国際会議プロシーディングス)
In this paper, a model estimating the time-dependent distribution of cluster size consisting of fine particles in Newtonian molten polymer was proposed. The present model for agglomerative suspension was developed based on Usui's thixotropy model, derived by taking the balance between shear breakup, shear coagulation and Brownian coagulation processes. The analysis was applied to the experimental results for silica/(ethylene methyl-meta acrylate copolymer) suspensions. The time variations of cluster size distributions, of viscosities and of the mean numbers of particles in a cluster were calculated and the results were compared with experimental results for the cases of shear rates from 0.2 to 10 s(-1) when the solid volume fraction was set at 0.15. From the results, it was found that the present model can estimated the steady state values of the slurry viscosity and the mean particle numbers in a cluster as well as Usui's original model. However, the model could not sufficiently express the time variation of theological characteristics due to the over-estimation of the contribution of shear rate when the cluster size is small. (C) 2008 The Society of Powder Technology Japan. Published by Elsevier BV and The Society of Powder Technology Japan. All rights reserved.
ELSEVIER SCIENCE BV, 2009年03月, ADVANCED POWDER TECHNOLOGY, 20 (2), 139 - 144, 英語[査読有り]
研究論文(学術雑誌)
The behavior of the particle agglomerate in a polymer melt in dispersion and agglomeration processes was investigated. In the dispersion process of particle agglomerates, number of agglornerated particles and shear viscosity of the mixture were decreased in a similar manner, and the agglomerated number was well correlated by applied strain. On the other hand, in the agglomeration process of having reduced the shear rate applied, agglomerated number was increased after the increase in shear viscosity, when the mixture contained particles at a high Volume fraction. Such a delay will be caused by the interaction between polymer entanglement structure and agglornerated particles. The internal structure of the mixture of particle and polymer was discussed in the consideration of frequency dependency of tan delta. When applying shear at shear rate more than the frequency where tan delta showed the maximum, particle agglomerate was dispersed well, and the interaction between polymer and single particle mainly governs rheological behavior. In addition, if smaller shear rate was applied to the mixture after that, relaxation of entanglement structure will induce particle agglomeration.
SOC RHEOLOGY, JAPAN, 2009年, NIHON REOROJI GAKKAISHI, 37 (3), 135 - 141, 日本語[査読有り]
研究論文(学術雑誌)
[査読有り]
研究論文(学術雑誌)
A model estimating the time-dependent distribution of cluster size consisting of fine particles in Newtonian molten polymer has been improved. The present model for agglomerative suspension was developed based on Usui's thixotropy model, derived by taking the balance between shear breakup, shear coagulation and Brownian coagulation process. The interparticle bonding energy in the model was assumed as a function of a cluster size in this study though it was assumed to be constant in the previous study. The analysis was applied to the experimental results for silica/(ethylene methyl-meta acrylate copolymer) suspensions. The time variation Of Cluster size distributions, of viscosities and of the mean number of particles in a cluster was calculated and the results were compared with experimental results mainly for the cases of the solid volume fractions from 0.10 to 0.25 when the shear rate was changed from 0.2 to 10 s(-1). From the results, it was found that the present model could estimate well the time dependency of cluster size distributions in a wide range of shear rate when the solid volume fraction was set at 0.15, and that the effect of the solid volume fraction was also sufficiently explained by the present model.
SOC RHEOLOGY, JAPAN, 2009年, NIHON REOROJI GAKKAISHI, 37 (4), 191 - 198, 英語[査読有り]
研究論文(学術雑誌)
A model For predicting the latex agglomerate size during the coagulation process, when (lie growth and breakup of the latex agglomerates proceed simultaneously tit a turbulent now, is proposed in this paper. In this model, the size of the agglomerate was expressed as it function of the external shear force, the strength of the agglomerate, and file volatile fraction of the slurry. The strength of the latex agglomerate was determined by a measurement or the slurry rheology in accordance with Usai's approach, where an inter-particle flooding energy between primary particles was calculated front the viscosity data. With this model, it was possible to predict the absolute size of the cluster in file turbulent flow. To confirm the validity of this model, the latex was agglomerated in various agitation conditions in the stirring vessel, while file dependence on volume fraction was also examined. The relation between file experimentally determined latex agglomerate sizes and the calculated agglomerate sizes from file proposed model was evaluated.
SOC CHEMICAL ENG JAPAN, 2009年, JOURNAL OF CHEMICAL ENGINEERING OF JAPAN, 42 (2), 71 - 77, 英語[査読有り]
研究論文(学術雑誌)
[査読有り]
研究論文(学術雑誌)
This report describes the particle distribution characteristics of an ice slurry treated with surfactants and brines generated by a vacuum production system. Ice particle size in slurries with surfactants was measured by an image-processing method at different concentrations of surfactant and brine. The results indicate that the effect of the ice fraction is very small on ice particle size obtained by the present vacuum production system. It was also found that the influence of brine concentration on particle size was very small. The effect of surfactant concentration on particle distributions was also very small. In addition, a small amount of surfactant reduced ice particle size compared to those of brine systems without surfactants. It is concluded that no brine system is economical for ice slurry generation by a vacuum production system.
SOC CHEMICAL ENG JAPAN, 2009年, JOURNAL OF CHEMICAL ENGINEERING OF JAPAN, 42 (6), 447 - 451, 英語[査読有り]
研究論文(学術雑誌)
The characteristics of liposome formation in a micro-tube have been studied to develop a novel production method that forms the liposomes with a desired size homogeneously. In this method, the inner wall of the micro-tube was used to spread the liposomal lipid on. Then, instead of conventional rigorous agitation, an aqueous solution was fed through the tube, which peeled off the thin lipid layer formed liposomes. This resulted in a sharp peak in the size-distribution profile, and the size of liposomes was found to be dependent on the flow velocity anti on the micro-tube size. Moreover, the Yield of the liposomes of the desired size in our method was much higher than that in the conventional method, because our method produced liposomes uniform in size. From these findings, we concluded that the friction drag in the micro-tube is applicable for the efficient production of liposomes and a microfluidics device consisting of micro-tubes is a promising tool in the production of liposomal formulations.
SOC CHEMICAL ENG JAPAN, 2008年08月, JOURNAL OF CHEMICAL ENGINEERING OF JAPAN, 41 (8), 739 - 743, 英語[査読有り]
研究論文(学術雑誌)
[査読有り]
研究論文(学術雑誌)
[査読有り]
研究論文(学術雑誌)
Three-dimensional numerical computations have been performed in order to investigate the mixing mechanism of a multi-holed (composed of two pairs of 4- and 5-hole elements) static mixer for Newtonian fluid. The hole Reynolds number based on the size ofstraight part of the hole and the mean velocity in a hole of the 5-hole element, Rea, was changed in three steps from 5.25 to 52.7, while the hole size of the straight part of the bole, the pipe diameter and fluid viscosity and density were fixed at 5 mm, 18 mm, and 0.0978 Pa.s and 1304 kg.m(-3), respectively, which were the same as in the previous experiments. From the results, it was found that twin vortices are formed in a hole of the 5-hole element as observed experimentally in the previous study. These twin vortices cause the twist motion in a hole and intensify the mixing process of the static mixer. It was also found that the vorticity of the twin vortices linearly increases with the hole Reynolds number. Thus, the increase of the hole Reynolds number causes high mixing characteristics as pointed out in the previous study.
SOC CHEMICAL ENG JAPAN, 2008年03月, JOURNAL OF CHEMICAL ENGINEERING OF JAPAN, 41 (3), 139 - 144, 英語[査読有り]
研究論文(学術雑誌)
Transition of the agglomerated state of particles in a molten polymer was investigated in dispersion and re-agglomeration processes. Moreover, the relationship between the number of agglomerated particles and shear viscosity was discussed. A steady shear was applied to the molten polymer containing spherical fine particles by using a cone plate type rheometer. Then, the number of agglomerated particles in a solidified polymer was evaluated. It was found that the dispersion behavior of agglomerated particles could well explain with strain, i.e. the deformation of a polymer. In the re-agglomeration process, the agglomerated number increased slowly compared with shear viscosity in case the shear rate in dispersion was large. It suggests that the inner structure of the polymer was maintained to a relatively high shear rate by coexistence of particles. When dispersed at further high shear rate, the agglomerated structure after the dispersion changed significantly and, as a results the re-agglomeration rate was drastically reduced.
AMER INST PHYSICS, 2008年, XVTH INTERNATIONAL CONGRESS ON RHEOLOGY - THE SOCIETY OF RHEOLOGY 80TH ANNUAL MEETING, PTS 1 AND 2, 1027, 108 - 110, 英語[査読有り]
研究論文(国際会議プロシーディングス)
Experimental studies on the relaxation characteristics of drag-reducing surfactants have been performed. The relaxation time after shear addition was measured by a cone-plate type rheometer in order to investigate the effect of the concentration of surfactants and counter-ions in the aqueous solution. The concentration of surfactants, oleylbishydroxyethylmethylanmonium chloride: Ethoquad O/12, was changed from 1,000 to 4,000 ppm, while the molar ratio of counter ions, sodium salicylate, to surfactants ranged from 1.5 to 100. From the results, it was found that the relaxation behavior of surfactant solution causing drag reduction shows multi-mode relaxation with several relaxation times and that the larger relaxation time decreases with the molar ratio of counter-ions and by the concentration of surfactants. The number of relaxation times was also found to decrease with the molar ratio of the counter-ions and concentration of surfactants.
AMER INST PHYSICS, 2008年, XVTH INTERNATIONAL CONGRESS ON RHEOLOGY - THE SOCIETY OF RHEOLOGY 80TH ANNUAL MEETING, PTS 1 AND 2, 1027, 860 - 862, 英語[査読有り]
研究論文(国際会議プロシーディングス)
In this paper, a model estimating the time-dependent distribution of cluster size consisting of fine particles in Newtonian molten polymer was proposed. The present model for agglomerative suspension was developed based on Usui's thixotropy model, derived by taking the balance between shear breakup, shear coagulation and Brownian coagulation process. The analysis was applied to the experimental results for silica/(ethylene meta-methyl acrylate copolymer) suspensions. The time variation of cluster size distributions, of viscosities and of the mean number of particles in a cluster was calculated and the results were compared with experimental results. From this, the applicability of the present model was validated for the agglomerative silica particles slurry.
AMER INST PHYSICS, 2008年, XVTH INTERNATIONAL CONGRESS ON RHEOLOGY - THE SOCIETY OF RHEOLOGY 80TH ANNUAL MEETING, PTS 1 AND 2, 1027, 653 - +, 英語[査読有り]
研究論文(国際会議プロシーディングス)
The coagulated behavior of latex particles in a seed coagulation was investigated. The latex particle formed the higher order coagulated structure, which consists of primary coagulates, and it was found that the temperature and the mixing condition significantly affected the size of cluster. We also proposed the procedure to predict the size of cluster from viscosity data of latex particle slurry by the use of the thixotropy model presented by Usui.
AMER INST PHYSICS, 2008年, XVTH INTERNATIONAL CONGRESS ON RHEOLOGY - THE SOCIETY OF RHEOLOGY 80TH ANNUAL MEETING, PTS 1 AND 2, 1027, 704 - 706, 英語[査読有り]
研究論文(国際会議プロシーディングス)
[査読有り]
研究論文(学術雑誌)
The dispersing behavior of a particle agglomerate in a mixture consisting of spherical fine particles and a molten polymer was investigated with the application of shear in a cone-plate apparatus. After attaining a constant agglomerated state by applying a small shear, the shear rate was changed to a set value and kept constant over a certain time. Viscosity measurement during shear application and analysis of particle agglomeration in a solidified mixture were conducted. In a dispersing process, agglomerates were broken up to a steady dispersed state corresponding to the shear rate applied and the average number of agglomerated particles could be well correlated by a deformation of the mixture in each particle volume fraction. The viscosity of the mixture with a particle loading of 0.15 had a good relationship with the agglomerated number independent of shear rate; thus, the viscosity of suspension may help in the understanding of the dispersing behavior. However, the concentrated mixture could not achieve a complete dispersion and the viscosity was significantly affected by the time response of the agglomerated structure to shear application, although a dynamic rheological measurement of mixtures with different particle loadings provided much the same result. (C) Koninklijke Brill NV, Leiden and Society of Powder Technology, Japan, 2008
ELSEVIER SCIENCE BV, 2008年, ADVANCED POWDER TECHNOLOGY, 19 (6), 507 - 521, 英語[査読有り]
研究論文(学術雑誌)
The 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.
SOC CHEMICAL ENG JAPAN, 2007年11月, JOURNAL OF CHEMICAL ENGINEERING OF JAPAN, 40 (11), 973 - 979, 英語[査読有り]
研究論文(学術雑誌)
The structure of the catalyst layer of PEFCs has a considerable influence on the cell performance. The catalyst layer is manufactured by coating a suspension consisting of Pt/C catalyst particles and a Nafion solution. In a catalyst layer, the decrease in the Pt/C particle agglomeration controlled by the coating condition was reported to improve the performance; however, the influence that the coating condition exerts on the structure and then performance of the catalyst layer when the compositions of suspension are different has not yet been researched well. In this study, we researched a method to control the structure of a catalyst layer by the coating condition and suspension composition. The surface structure, which is well correlated with the predicted number of agglomerated Pt/C particles, showed good agreement with the performance. Under the condition where the Pt/C particles are not dispersed well, the performance was improved with an increase in the coating speed and Nafion content. However, that improvement became negligible at the optimum Nafion content providing maximal cell performance. Further, at a higher Nafion content, the excessive dispersion of Pt/C particles in the catalyst layer deteriorated the performance drastically. These results imply that the performance improvement by coating is effective when the suspension shows fairly high viscosity. Further, a little addition of solvent to decrease the viscosity also improves the performance; however it may be deteriorated by an excessive addition.
SOC CHEMICAL ENG JAPAN, 2007年10月, JOURNAL OF CHEMICAL ENGINEERING OF JAPAN, 40 (10), 808 - 816, 英語[査読有り]
研究論文(学術雑誌)
The correlation of fluidity between solid-liquid and solid gas suspensions was examineed using the thixotropy model proposed by Usui et al., (2000a, 2000b, 2001) Shear-thinning behavior was observed for a solid-gas suspension of calcium carbonate particles. The decrease in apparent viscosity of the solid-gas suspension is attributed to the breakdown of agglomerative structure with the increase in shear rate. It was found that the predicted inter particle bonding energy for the solid-gas suspension corresponded well to that obtained for a solid-liquid suspension. The same tendency was reported previously for the case of silica suspension. Since the suspension viscosity is not greating sensitive the change in inter particle bonding energy, it may be possible to predict solid-gas suspension viscosity by predicting the inter particle bonding energy for a solid-liquid suspension, and by using the thixotropy model proposed by the present authors.
SOC CHEMICAL ENG JAPAN, 2007年07月, KAGAKU KOGAKU RONBUNSHU, 33 (4), 315 - 318, 日本語[査読有り]
研究論文(学術雑誌)
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研究論文(学術雑誌)
[査読有り]
研究論文(学術雑誌)
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研究論文(学術雑誌)
A two dimensional numerical study on flow and heat transfer of viscoelastic fluid in a cavity has been performed in order to investigate how effective the heat transfer augmentation technology is by using the Burns effect in the region of low Reynolds and Weissenberg numbers on the bottom wall of the cavity between ribs mounted in the parallel plates. In this paper, the heat transfer characteristics on the bottom of the cavity were focused on. The cavity length and the rib height were changed in three steps, respectively, while the wide flow path width and the solid wall temperature were kept constant. The solvent Reynolds number based on the rib height was set at 100. From the results, it is found that the flow penetration into the cavity effectively occurs just at the inlet of the cavity in the cases of viscoelastic fluids, while a large recirculating region is formed there for the cases of water. The local Nusslt number takes peaks at the position corresponding to the peak positions of velocity gradients on the bottom wall. It is also found that the mean Nusselt number increases with rib height and cavity length. However, the increase rate on the cavity length becomes smaller in a large cavity length region. This indicates there exists the optimum geometric condition and that the present technology has an advantage for making the heat exchanger compact in comparison with that using a water flow.
SOC CHEMICAL ENG JAPAN, 2006年09月, JOURNAL OF CHEMICAL ENGINEERING OF JAPAN, 39 (9), 915 - 923, 英語[査読有り]
研究論文(学術雑誌)
[査読有り]
研究論文(学術雑誌)
The mixing characteristics of a multi-holed static mixer have been studied for Newtonian fluid. A multi-holed static mixer composed of five pairs of 4- and 5-hole elements. The size of straight part of the hole, a, was changed in two steps of 2 mm and 5 mm and its inlet and outlet size, d, was also changed in two steps of 4 or 6 mm in the cases of a = 2 rum. The fluid viscosity and flow rate were also changed as parameters. Flow visualization experiments in a test pipe with 18 mm diameter were performed in order to observe the occupation ratio of dyed fluid, which is injected from the nozzle with 4 mm diameter mounted in the upstream of the static mixer. From the results, it is found that the Reynolds number based on the mean velocity in the 4 hole element and the hole size, Re-s, multiplied by a delivery ratio of the hole, d/a, well correlates the mixing and pressure loss characteristics. This is because there exist two mixing processes in the present static mixing system. One is the mixing process in a small hole by accelerated flow and the other is a delivery effect between holes.
SOC CHEMICAL ENG JAPAN, 2006年08月, JOURNAL OF CHEMICAL ENGINEERING OF JAPAN, 39 (8), 807 - 813, 英語[査読有り]
研究論文(学術雑誌)
[査読有り]
研究論文(学術雑誌)
[査読有り]
研究論文(学術雑誌)
Phase-change slurry is a promising fluid for a district heating and cooling system. In this work, hydrodynamics and heat transfer characteristics of drag reducing trim ethy lolethane (TME: CH3C(CH2OH)(3)) solution and suspension by cationic surfactant were studied. Oleyl bishydroxyethyl methyl ammonium chloride (trade name: Ethoquad O/12) was used as the surfactant, while sodium salicylate (NaSal) as counter-ion. Two kinds of experiments were conducted, namely pressure drop/friction factor and heat transfer measurements. From friction factor measurements, it is found that surfactant can induce drag reduction (DR) in TME solution/suspension. It is also found that TME molecule reduces the DR capability. From heat transfer measurement, it is found that surfactant induces heat transfer reduction (HTR) in TME solution and suspension. It is also revealed that Colburn analogy cannot be applied for TME suspension or drag-reducing TME solution and suspension. By using a correction factor for the Colburn analogy, application of the analogy for the drag-reducing TME solution is improved. At low velocity, HTR is higher than the DR, but at high velocity (just before DR is lost) both HTR and DR are nearly the same.
SOC CHEMICAL ENG JAPAN, 2006年06月, JOURNAL OF CHEMICAL ENGINEERING OF JAPAN, 39 (6), 623 - 632, 英語[査読有り]
研究論文(学術雑誌)
The effect of hydrophilic head of drag reducing cationic surfactants on the micellar structures has been studied by using fluorescence probe technique. Sodium 3-hydroxy-2-naphthoate, NaHN, has been used as a fluorescence probe in these experiments. Four types of surfactants having the same alkyl chain but different in number of hydroxyethyl, HE, group changed from 0 to 3 have been tested. A method of calculating the molar ratio of free counter-ions is suggested with the fluorescence decay behavior of counter-ion. From the results, it is found that the lifetime of fluorescence decay in micellar interior phase decreases while the molar fraction of free counter-ion increases when the HE group number increases. It is also found from the results on the molar ratio of free counter-ions and the comparison of Stokes diameters that the decrease of the critical Reynolds number is related to the number density of micellar structures and its strength.
SOC RHEOLOGY, JAPAN, 2006年, NIHON REOROJI GAKKAISHI, 34 (1), 17 - 23, 英語[査読有り]
研究論文(学術雑誌)
It is important that we clarify the interaction between particles in particle processing. The interaction between particles tinder shear flow is considered to be evaluated by energy dissipation. i.e. viscosity, in a powder layer. By measuring the torque exerted on the mixing blade of a powder rheometer, the viscosity of the powder layer could be calculated. The viscosity decreased with the blade velocity and such a shear thinning rheological property is similar to that observed for solid-liquid suspensions. By applying the suspension rheology model. which was developed for the evaluation of the agglomeration state of solid-liquid mixtures under shear flow. particle agglomeration around the blade under dry powder flow conditions was evaluated. As the shear rate increases, the size of agglomerated particle clusters is proved to decrease. At high shear rate or low solid volume fraction, the inter-particle bonding energy is revealed to be constant independent of the shear rate and solid volume fraction.
VSP BV, 2006年, ADVANCED POWDER TECHNOLOGY, 17 (3), 333 - 343, 英語[査読有り]
研究論文(学術雑誌)
Hydrodynamic characteristic of surfactant drag-reducing flows is still not fully understood. This work investigated the temperature and diameter effect on hydrodynamic characteristic of cationic surfactant drag reducing flows in pipes. Solution of oleyl bishydroxyethyl methyl ammonium chloride (Ethoquad O/12), 900 ppm, as a cationic surfactant and sodium salicylate (NaSal), 540 ppm, as a counter-ion was tested at 12, 25, 40, and 50 degrees C in pipes with diameter of 13, 25, and 40 mm. Drag reduction effectiveness of this surfactant solution was evaluated in 25 mm pipe from 6 to 75 degrees C. Rheological characteristic of this solution was measured by stress control type rheometer with cone-and-plate geometry. Scale-up laws proposed by previous investigators were used to evaluate the flow characteristic of the Solution. It was found that this surfactant solution has clear DR capability until 70 degrees C. Result of this work Suggested that temperature has a significant influence in changing the hydrodynamic entrance length of surfactant drag reducing flows. From rheological measurement, it was found that the solution exhibits Shear Induced Structure at all temperatures with different degree of peak viscosity and critical shear rate.
KOREAN SOC RHEOLOGY, 2005年12月, KOREA-AUSTRALIA RHEOLOGY JOURNAL, 17 (4), 157 - 164, 英語[査読有り]
研究論文(学術雑誌)
Development behavior of the fluctuating velocity of surfactant solution in a duct has been studied experimentally. The concentration of surfactants was kept constant at 1,000 ppm, mean velocity at 0.78 m/s and fluid temperature at 15 degrees C. Using laser Doppler velocimetry, the fluctuating streamwise velocity distributions at six cross sections, which ranged from 14 to 112 times of hydraulic diameter of the duct, were measured. From the results, the fluctuating structures of surfactant solution flow are observed to have structures different from that of turbulent water flow in the developing field. The wavelet analysis reveals that the high-level fluctuation of surfactant solution flow is characterized by periodicity rather than irregularity around the position where the fluctuation intensity takes a peak value and that the period and the scale of periodic flow structures are related to the relaxation times of the fluid. This indicates that the high-level fluctuation is deeply related to the elastic instability and has a different generation mechanism from that of turbulence observed in a Newtonian turbulent flow.
SPRINGER, 2005年07月, RHEOLOGICA ACTA, 44 (5), 457 - 464, 英語[査読有り]
研究論文(学術雑誌)
[査読有り]
研究論文(学術雑誌)
[査読有り]
研究論文(学術雑誌)
[査読有り]
研究論文(学術雑誌)
The present paper reviews the technologies on preventing the agglomeration and the growth of ice particles in water with a very small amount of suitable additives. This summarizes studies on the effects of anti-agglomeration of ice particles and suppression of ice growth by using anti-freeze protein and its substitutes or some kinds of surfactants, and on their applications to ice slurry making systems, and to the coupling technology with surfactant drag reduction of ice slurries. These anti-agglomeration additives are found to well disperse ice particles in water at a very low concentration without a serious depression of the equilibrium freezing temperature. This is concluded to improve the ability of ice slurries as a secondary refrigerant. (C) 2004 Elsevier Ltd and IIR. All rights reserved.
ELSEVIER SCI LTD, 2005年01月, INTERNATIONAL JOURNAL OF REFRIGERATION-REVUE INTERNATIONALE DU FROID, 28 (1), 20 - 26, 英語研究論文(学術雑誌)
[査読有り]
研究論文(学術雑誌)
[査読有り]
研究論文(学術雑誌)
研究論文(学術雑誌)
研究論文(学術雑誌)
研究論文(学術雑誌)
The biaxial extensional characteristics of a cationic surfactant solution system showing an effective drag reduction in pipe flow have been studied by using two opposed nozzle devices. Aqueous solutions of cationic surfactant, oleylbishydroxyethylmethylammonium chloride, at the concentrations varied from 250 to 1,000 ppm with sodium salicylate, which ionized to counter-ion in an aqueous Solution, of which molar ratio to surfactant was set at 1.5, were tested. Especially, time characteristics of extensional stress were focused in wide ranges of surfactant concentration and extensional rate. From the results, the apparent extensional viscosity is found to depend on the extensional rate and oil the surfactant concentration. For the extensional rate dependency, the extensional viscosity behavior is classified into four regions. This characteristic is considered to be caused by the formation and the deformation of the surfactant rodlike micellar network structure. In each region, the build-up and relaxation times are not strongly affected by the concentration of the surfactant. On the other hand, the build-up time decreases with a gradient of -1 in a double logarithm plot to the extensional rate, while the relaxation time decreases weakly with the extensional rate. The former fact indicates the micellar network formation occurs due to the collision of surfactant micelles. It is also found that two relaxation processes exist for the extensional flow cases. The shorter or the longer relaxation time takes almost the same value as each value corresponding to that for the shear flow release condition. This indicates the network structure size formed in the biaxial extensional flow takes almost the same as that in the shear flow.
SOC RHEOLOGY, JAPAN, 2005年, NIHON REOROJI GAKKAISHI, 33 (3), 145 - 150, 英語[査読有り]
研究論文(学術雑誌)
Certain surfactants with suitable brine, such as cetyldimethylbetaine with sorbitol, can inhibit agglomeration of ice particles and thus help disperse ice particles in ice/water slurries, and simultaneously reduce the drag of the slurry in pipes. In this study, the amount of cetyldimethylbetaine (surfactant) molecules remaining in the liquid phase of ice/water slurries was measured, and on the basis of these measurements, models explaining how cetyldimethylbetaine molecules affect ice to inhibit agglomeration of ice particles were proposed.
CHEMICAL SOC JAPAN, 2004年12月, CHEMISTRY LETTERS, 33 (12), 1558 - 1559, 英語[査読有り]
研究論文(学術雑誌)
Surfactant drag reduction is a promising technology to reduce the pumping power of district heating-cooling systems. Many investigations have been reported to give a clear prospect of the drag-reducing phenomenon. However, the mechanism of surfactant drag reduction and the microstructure of surfactant micelles are still left unknown. This study aims to provide an experimental evidence of the effect of counter-ions on the micelle structure and the surfactant drag reduction in a pipe flow. The present authors have been investigating the surfactant drag reduction with a cationic surfactant with suitable counter-ions (sodium salicylate). The effect of the molar ratio of the counter-ion to the cationic surfactant is discussed using the experimental results on the drag reduction in a turbulent pipe flow, on the micelle size and on the shear thinning-thickening viscosity. These experimental results suggest that a new drag-reducing state exists at very high molar ratios of the counter-ion to the surfactant. This new state gives a remarkable drag reduction, but shows very weak viscoelasticity. The optimum molar ratio to cause a strong viscoelasticity is (surfactant): (counter-ion) = 1:1.5, but at higher molar ratios, the elongational viscosity decreases, while high drag reduction effectiveness is kept. The micelle structure could be changed at higher counter-ion molar ratio, but this new structure may also be effective for drag reduction.
SOC CHEMICAL ENG JAPAN, 2004年10月, JOURNAL OF CHEMICAL ENGINEERING OF JAPAN, 37 (10), 1232 - 1237, 英語[査読有り]
研究論文(学術雑誌)
[査読有り]
研究論文(学術雑誌)
Development characteristics of dilute cationic surfactant solution flow have been studied through the measurements of the time characteristics of surfactant solution by birefringence experiments and of the streamwise mean velocity profiles of surfactant solution duct flow by a laser Doppler velocimetry system. For both experiments, the concentration of cationic surfactant (oleylbishydroxymethylethylammonium chloride: Ethoquad O/12) was kept constant at 1000 ppm and the molar ratio of the counter ion of sodium salicylate to the surfactants was at 1.5. From the birefringence experiments, dilute surfactant solution shows very long retardation time corresponding to micellar shear induced structure formation. This causes very slow flow development of surfactant solution in a duct. Even at the end of the test section with the distance of 112 times of hydraulic diameter form the inlet, the flow is not fully developed but still has the developing boundary layer characteristics on the duct wall. From the time characteristics and the boundary layer development, it is concluded that the entry length of 1000 to 2000 times hydraulic diameter is required for fully developed surfactant solution flow.
SPRINGER-VERLAG, 2004年05月, RHEOLOGICA ACTA, 43 (3), 232 - 239, 英語[査読有り]
研究論文(学術雑誌)
Development characteristics of dilute cationic surfactant solution flow have been studied through the measurements of the time characteristics of surfactant solution by birefringence experiments and of the streamwise mean velocity profiles of surfactant solution duct flow by a laser Doppler velocimetry system. For both experiments, the concentration of cationic surfactant (oleylbishydroxymethylethylammonium chloride: Ethoquad O/12) was kept constant at 1000 ppm and the molar ratio of the counter ion of sodium salicylate to the surfactants was at 1.5. From the birefringence experiments, dilute surfactant solution shows very long retardation time corresponding to micellar shear induced structure formation. This causes very slow flow development of surfactant solution in a duct. Even at the end of the test section with the distance of 112 times of hydraulic diameter form the inlet, the flow is not fully developed but still has the developing boundary layer characteristics on the duct wall. From the time characteristics and the boundary layer development, it is concluded that the entry length of 1000 to 2000 times hydraulic diameter is required for fully developed surfactant solution flow.
SPRINGER-VERLAG, 2004年05月, RHEOLOGICA ACTA, 43 (3), 232 - 239, 英語[査読有り]
研究論文(学術雑誌)
Latent heat transportation by ice/water slurry is an effective technology to establish the energy saving air conditioning system. Modak et al. (2002) reported a new surfactant system in which the good agglomeration control of ice particles was available, and effective turbulent drag reduction was simultaneously attained. However, this system needed the addition of a considerable amount of sodium chloride. In this raper, the combined use of zwitterionic surfactant with a suitable brine with no corrosive characteristic is proposed to prepare ice/water slurry. It is certified that newly prepared ice/water slurry shows a good dispersion condition of ice particles and the flowability of the slurry is much improved if it is compared with the previous ice/water slurries. The ice/water slurry thus obtained is promising for the use of the high efficiency heat transportation technology by utilizing surfactant drag reduction and latent heat transportation.
SOC CHEMICAL ENG JAPAN, 2004年01月, JOURNAL OF CHEMICAL ENGINEERING OF JAPAN, 37 (1), 15 - 22, 英語[査読有り]
研究論文(学術雑誌)
It is known that the particle characteristics and method of coating affect the performance of the electrode in PEMFC technology. The slurry to be used for the preparation of the PEMFC electrode is the suspension of carbon-supported Pt nano-particles (Pt/C) in a Nafion solution. The agglomeration nature of this slurry is obtained both experimentally and theoretically. Information on slurry dispersion is compared with the cross sectional SEM image of the membrane. It is certified that there exists a good correlation between agglomeration characteristic length and the void diameter observed in SEM images. The evaluation of PEMFC electrode performance is done by using several kinds of electrode membranes prepared under different coading speeds. Slight increases both in cell voltage and internal resistance are observed for the case of cathode performance experiments according to the increase of the coating speed. On the other hand, no effect of the coating speed is detected for the case of anode performance experiments due to the cell voltage results were affected mainly by the electrocatalytic activity of the cathode, which results in no effect of the agglomeration. It is concluded that higher coating speed is preferable to get good PEMFC electrode performance within the range of the present experimental conditions.
SOC CHEMICAL ENG JAPAN, 2004年01月, JOURNAL OF CHEMICAL ENGINEERING OF JAPAN, 37 (1), 31 - 39, 英語[査読有り]
研究論文(学術雑誌)
[査読有り]
研究論文(学術雑誌)
[査読有り]
研究論文(学術雑誌)
Since the microstructure of functional thin films depends on the dispersion characteristics of dense slurry, it is important to control the agglomerative nature of slurries under processing. The present authors have been discussing the model prediction of agglomerative nature and local rate of agglomeration in dense suspensions. The experiments have been performed under shear flow using the nearly spherical and oblate type graphite particles. In this study, the experiment has been conducted using water and glycerol as dispersion media. Stress control type rheometer was used to measure the slurry rheology. Local agglomeration of graphite particles has been predicted by using Usui's model. The experimental results show that both the shape and slurry processing method affect on the local dispersion condition. The agglomeration formed by oblate type graphite particles seems to be more difficult to break up than that of spherical particles.
KOREAN SOC RHEOLOGY, 2003年03月, KOREA-AUSTRALIA RHEOLOGY JOURNAL, 15 (1), 19 - 25, 英語[査読有り]
研究論文(学術雑誌)
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研究論文(国際会議プロシーディングス)
[査読有り]
研究論文(国際会議プロシーディングス)
研究論文(国際会議プロシーディングス)
[査読有り]
研究論文(国際会議プロシーディングス)
研究論文(国際会議プロシーディングス)
This paper proposes a long distance pipeline transportation system with an additive feeding system suitable for restarting after more than a 24-hour shut down. The aim of the investigation is to find suitable stabilizing additives for fly ash-water slurry to prevent sedimentation during an interrupted period of pipelining. Rheological characteristics and sedimentation stability of the slurry with the addition of four kinds of stabilizing additives were measured. Additives used in this study were rhamsan gums, carboxymethyl cellulose, and xanthan gum. The stable slurry was fed in the pipeline, instead of the normal slurry, before the pipeline was shut down. From the predicted viscosity, using Usui's thixotropy model, the relationship between flow rate and pressure drop has been estimated for the transportation of the slurry. A feasibility study for the new transport system was also performed. Copyright © 2002 Taylor & Francis.
Informa UK Limited, 2002年03月, Coal Preparation, 22 (2), 65 - 80, 英語[査読有り]
研究論文(学術雑誌)
研究論文(国際会議プロシーディングス)
[招待有り]
研究論文(国際会議プロシーディングス)
[査読有り]
研究論文(国際会議プロシーディングス)
[査読有り]
研究論文(国際会議プロシーディングス)
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研究論文(国際会議プロシーディングス)
[査読有り]
研究論文(国際会議プロシーディングス)
In this study, we investigated the influence of the number of ethanol (EO) groups of cationic surfactants having one oleyl group on the drag-reducing effect (DR effect). Also the effect of mechanical pumping power on DR effect was experimentally investigated using two experimental setups, a circulation system (with pump) and a pressurized once-through system (without pump). The concluding remarks obtained in this study are: 1. The DR effect strongly depends on the re-formation rate of micelles disrupted mechanically. 2. When increasing the number of EO groups of the DR surfactants from 0 to 2, the available temperature range of large DR effect was shifted lower. But the DR surfactant having three EO groups (EO-3) barely exhibited the DR effect even at the low temperature. This is because the big hydrophilic head of EO groups probably delays the re-formation of micelles disrupted by pumping power. 3. The DR effect was more liable to be influenced by pumping power with a decrease in temperature. This is because it takes a long time to re-form micelles disrupted by pumping power at low temperature.
2002年, Chemical Engineering Communications, 189 (12), 1671 - 1683, 英語[査読有り]
研究論文(学術雑誌)
An ice-water slurry system with surfactant additives is a potential working fluid for transporting thermal energy in an air-conditioning system. In this paper, two types of surfactant additives have been studied: (1) a nonionic surfactant additive (Tween® 80 system) and (2) a mixture of zwitterionic surfactant, cetyl dimethyl betaine, and sodium oleic acid as an anionic surfactant additive (betaine system). Sodium chloride is added as a supplementary agent in both of the systems. The ice-water slurry with the betaine system produced smaller ice particles than the Tween 80 system. Thus, the betaine system in the ice-water slurry can better prevent the growth of agglomeration of ice crystals than the Tween 80 system. The relative viscosity of the ice-water slurry with the betaine system is lower than that of the Tween 80 system, which means that the ice-water slurry with the betaine system is more dispersed than in the Tween 80 system. Also, the betaine system causes drag reduction in the pure liquid phase at room temperature, whereas the Tween 80 system shows no drag reduction. Therefore, it can be expected that the betaine system can better prevent the growth of agglomeration of ice crystals and control the dispersion of ice particles in the ice-water slurry system. © 2002 Taylor & Francis Group, LLC.
2002年, HVAC and R Research, 8 (4), 453 - 466, 英語[査読有り]
研究論文(学術雑誌)
This paper reports how heat transfer can be augmented by inserting a micelle squeezer at the inlet of the turbulent pipe flow drag-reduced by surfactant additives. The micelle squeezer gives very high shear to the flow and the rod-like micelles formed with surfactant molecules, which remarkably reduce both drag force of the flow and heat transfer, are broken by the high flow shear at the flow inlet. From this, the drag force is recovered in the very limited region below the micelle squeezer, but also heat transfer is recovered in the enough regions required for exchanging heat. This strategy can be applied for heat exchangers, which occupy the small part of district cooling flow system.
Japan Society of Mechanical Engineers, 2002年, 日本機械学会論文集B編, 68 (666), 469 - 472, 日本語[査読有り]
研究論文(学術雑誌)
The prediction of slurry viscosity for the suspensions with and without particle size distribution has become possible by using the suspension rheology model proposed in this study. The viscosity prediction model is based on Simha's cell model, which is applicable to completely dispersed systems. It was verified experimentally that the Simha's model was able to predict the slurry viscosity for the case of the suspensions with particle size distribution. The present suspension rheology model adopted the assumption that the effect of agglomeration appeared only for the cluster formation with the minimum sized particles, and the other larger particles were completely dispersed. The same type of rheology model was previously proposed by one of the present authors, but the model was modified to give more accurate viscosity predictions. The present model makes the assumption that multi-break up of inter-particle bonding occurs when a cluster breaks into two parts under a simple shear flow. It is demonstrated that the present model combined with the Simha's cell model can be successfully used to predict the rheological behavior of slurries. © 2001 Elsevier Science Ltd. All rights reserved.
Elsevier BV, 2001年05月29日, Chemical Engineering Science, 56 (9), 2979 - 2989, 英語[査読有り]
研究論文(学術雑誌)
Prediction of the maximum packing volume fraction with non-spherical particles has been one of the important problems in powder technology. The sphericity depending on the particle diameter was measured by means of an image processing instrument. An algorithm to predict the maximum packing volume fraction with non-spherical particles is proposed. The maximum packing volume fraction was used to predict the slurry viscosity under well dispersed conditions. For this purpose, Simha's cell model was applied for concentrated slurry with wide particle size distribution. Also, Usui's model developed for aggregative slurries was applied to predict the non-Newtonian viscosity of dense fly ash-water slurry. It was certified that the maximum packing volume fraction for non-spherical particles can be successfully used to predict slurry viscosity, and this means indirectly the maximum packing volume fraction determined in this study is reasonable.
Society of Chemical Engineers, Japan, 2001年03月, Journal of Chemical Engineering of Japan, 34 (3), 360 - 368, 英語[査読有り]
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[査読有り]
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[査読有り]
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研究論文(国際会議プロシーディングス)
Two-dimensional numerical computations were performed to investigate non-absorbable gas diffusing behavior in the evaporator-absorber in an absorption chiller. In this paper, special attention was paid to the effect of initial condition of non-absorbable gas distribution. When non-absorbable gas is distributed uniformly in the evaporator-absorber, overall heat transfer coefficient does not markedly decrease until the mean concentration of non-absorbable gas becomes 5 vol%. On the other hand, when non-absorbable gas is injected at a point near the upper corner of the evaporator in the same way as in the experiments, overall heat transfer coefficient markedly decreases and agrees with the experimental results. This indicates that the initial condition of non-absorbable gas distribution seriously affects the heat transfer characteristics of the absorber.Under uniform initial conditions, non-absorbable gas is kept in the recirculation region formed between the evaporator and the absorber when the mean concentration of non-absorbable gas is small. Upon injection, however, non-absorbable gas penetrates deeply into the upper region of the absorber. This causes the recirculation region disappearance. Then, the heat transfer markedly decreases in the absorber. Key words: absorption chiller, non-absorbable gas, vapor flow, numerical simulation. © 2001, The Society of Chemical Engineers, Japan. All rights reserved.
Society of Chemical Engineers, Japan, 2001年, 化学工学会論文集, 27 (5), 581 - 587, 英語[査読有り]
研究論文(学術雑誌)
[査読有り]
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[査読有り]
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研究論文(国際会議プロシーディングス)
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A thixotropy model is developed for the prediction of the viscosity of silica suspensions. The model can be applied for the prediction of non-Newtonian viscosity of agglomerative suspensions with particle size distribution. Since the model assumed that the particle shape was spherical, a mixture of mono-modal spherical silica particles was used to prepare the concentrated suspensions. Viscosity measurement results have proved that the present model was able to predict the non-Newtonian suspension viscosity under steady simple shear flow conditions, although more discussion on the physical meaning of inter-particle bonding energy was needed. The applicability of the present model must be checked for the suspensions prepared using non-spherical particles with particle size distribution in the future. © 2000, The Society of Chemical Engineers, Japan. All rights reserved.
Society of Chemical Engineers, Japan, 2000年, 化学工学会論文集, 26 (3), 423 - 430, 英語[査読有り]
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[査読有り]
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研究論文(国際会議プロシーディングス)
研究論文(国際会議プロシーディングス)
研究論文(国際会議プロシーディングス)
研究論文(国際会議プロシーディングス)
[査読有り]
研究論文(学術雑誌)
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Numerical calculations have been performed for isothermal, laminar, three-dimensional flow past one or two fixed obstructions radially aligned and symmetrically located between a pair of disks corotating in a fixed cylindrical enclosure. The single-obstruction cases respectively model the influence on the flow of (a) a magnetic head arm support and (b) an air lock. The dual-obstruction cases model the simultaneous presence of these two objects. The air lock produces an interdisk cross-stream plane blockage of 62 percent while the two head arm supports produce blockages of 31 percent and 62 percent, respectively. For the cases with the air lock and arm support simultaneously present, the circumferential angle between them is fixed to 40 or 80 deg. Velocity, pressure, shear stress and the disk torque coefficient are predicted mostly for a Reynolds number (Re=ΩR22/v) corresponding to 10,000, approximately, where R2, Ω, and v are the disk radius, the disk angular velocity in rad/s, and the kinematic viscosity of air at 300 K, respectively. The calculations show that a large blockage significantly alters the interdisk flow characteristics by markedly raising the pressure ahead of an obstruction and accelerating the flow through the empty space around it. This induces a detached region of reversed flow ahead of the obstruction, quite distinct from that in its wake. The disk surface pressure distributions point to a potential source of dynamical instability in rotating disk flows with obstructions. By redefining the torque coefficient and Reynolds number to account for dual blockage effects the relationship between these two quantities generally follows the theoretical expression of Humphrey et al. (1992). It is shown that the bulk of the drag on an obstruction is form drag as opposed to friction drag.
ASME International, 1997年09月01日, Journal of Fluids Engineering, 119 (3), 499 - 505, 英語[査読有り]
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Flow characteristics of visco-elastic fluids sweeping a micro-cavity mounted in a micro-duct have been investigated in order to develop a novel technique of a mixing process for micro-reactors. In this paper, effects of the Reynolds number and of the rheological characteristics of the fluids were focused on. The cavity depth, the cavity length and the width of the wider flow path were fixed at 200, 1,000 and 400 u,m, respectively. As a visco-elastic fluid, a solution of cationic surfactants with counter-ions was used. The molar ratio of counter-ions to surfactants was changed in four steps in order to change the rheological characteristics of the visco-elastic fluids. The Reynolds number was also changed from 0.100 to 100. From the results, it was found that a tonguing motion of the separation fluid bubble tip formed in the downstream region in the cavity occurs at a certain Weissenberg number larger than 200 due to the elastic instability. The fluctuating bulge structure was also observed on the upstream side wall of the cavity in a higher range of the Weisenberg number. Such an elastic instability can be expected a suitable micro-fluid motion for the micro-mixing.
一般社団法人日本機械学会, 2014年09月07日, 年次大会 : Mechanical Engineering Congress, Japan, 2014, "S0520203 - 1"-"S0520203-6", 日本語Solution containing little amount of polymers shows complex behavior, such as drag reduction effects and elastic turbulence. These phenomena are due to viscoelasticity of polymers. However, little study has been made to measure a relationship between polymers and solution directly. In this study, we have tried to measure frictional drag of polymers added by fluids. In order to measure it, Atomic Force Microscope (AFM) was used. Polymers having a thiol group at the terminus were attached to a gold-coated cantilever of the AFM. The cantilever was swept in solution. When polymers were attached to the cantilever, the cantilever detects additional force due to polymers. It was assumed that the polymers cover the cantilever as saturated adsorption, and all polymers induce force due to Stokes drag. This force was calculated by Stokes equation, which is indeed reasonably fit to the force measured by AFM.
一般社団法人日本機械学会, 2014年09月07日, 年次大会 : Mechanical Engineering Congress, Japan, 2014, "J0440105 - 1"-"J0440105-3", 日本語A numerical analysis of unsteady behavior of particle aggregation/dispersion was performed in a non-uniform shear flow in a cylinder with a rotating elliptical rotor. In this model, it was considered that an aggregation/dispersion rate depends on Brownian coagulation, shear coagulation and shear breakup. Immersed boundary method was used to calculate a flow with rotating rotor. The diameter of the cylinder was 38 mm. The major and minor axes of the elliptical rotor were 32 and 26.6 mm. The rotor was rotated at 20 RPM. The diameter of particles and the viscosity of disperse media were 2.5 ?m and 195 Pa s. As a result, the cluster was broken by applying shear and the size of cluster decreased with time. The particle dispersion behavior varies with local position. The mean cluster size took a minimum value right after the major axis of the rotor passed. Then the mean cluster size increased again.
一般社団法人日本機械学会, 2013年11月09日, 流体工学部門講演会講演論文集, 2013, "0101 - 01"-"0101-02", 日本語The characteristics of oxygen-dissolution accelerated by use of micro-bubbles in a viscoelastic fluid have been studied. An aqueous solution of a combination of a cationic surfactant and of a counter-ion supplier was used as a viscoelastic fluid. Flow visualizations and the time-variation of oxygen concentration measurements were performed. From the results, it was found that the dissolution of oxygen rapidly occurs by use of micro-bubbles, but that the dissolution becomes slow in a high elastic fluid. The flow observation of bubbles in a high elastic fluid showed a chaining effect with the bubble ascension. The bubble chaining accelerates agglomeration of bubbles and decreases apparent gas-liquid interface area. Thus, such a chaining effect was concluded to disturb the dissolution of oxygen.
一般社団法人日本機械学会, 2013年09月08日, 年次大会 : Mechanical Engineering Congress, Japan, 2013, "S051015 - 1"-"S051015-5", 日本語Liposomes produced from lipids have been studied as promising materials for a drug delivery system (DDS), since the liposomes are relatively non-toxic and biodegradable. For using liposomes as a drug carrier, the size of liposomes and the homogeneity in their structure are the most important characteristics. In this study, a novel technique of liposome production using a gas/liquid interface in a T-shape micro-duct has been suggested. By this method, the liposomes can be obtained without harmful organic solvents and the miniaturization of liposome production can be realized. The behaviors of gas columns and liquid columns in the micro-duct were changed depending on flow rate. Diameters of the liposomes were decreased by increase of the flow rate. The diameters of liposomes seemed to be affected by the length of liquid columns. Thus, flow characteristics in a liquid column were also analyzed.
一般社団法人日本機械学会, 2013年09月08日, 年次大会 : Mechanical Engineering Congress, Japan, 2013, "J044041 - 1"-"J044041-4", 日本語An experimental study has been performed in order to investigate the optimum rheological characteristics for a technique of heat transfer augmentation in a cavity between ribs mounted in parallel plates.The rheological characteristics of visco-elastic fluid were changed by controling the molar ratio of counter-ion to a cationic surfactant.Flow visuarization experiments and pressure loss measurements were conducted in this study.From the results,it was found flow penetration into the cavity occurred in the cases from 1 to 5 of molar ratio of counter-ions.The pressure loss was also found to become almost the same as that of water in the case when the molar ratio of counter-ions was set at 5.From this,it was concluded that the optimum fluid for the heat transfer augmentation in a cavity is required to have suitable elasticity and low viscosity as the molar ratio of counter-ions is set at 5.
一般社団法人日本機械学会, 2012年11月16日, 流体工学部門講演会講演論文集, 2012, 411 - 412, 日本語An experimental study has been performed in order to investigate the relationship between the extensional viscosity of polymers and the turbulent drag reduction.Polyethyleneoxide as a flexible polymer and hydroxypropyl cellulose as a rigid rod-like polymer were added to the two-dimensional turbulence that was visualized by the interference pattern of the flowing soap films and analyzed by an originally-developed single-image analysis.The power spectra of interference images were obtained,which is related to the water layer fluctuations in turbulence.The power spectra show a scaling behaviour and the power components give the information of drag reduction.Wavelet-coefficient was also calculated.It was found from these results that the energy transfer mechanisms are different in streamwise and normal directions.In the normal direction,the energy transfer is prohibited by the orientation of polymers,while the energy transfer in the streamwise direction is prohibited by extensional viscosity of polymers.The characteristic scales for the energy transfer were also observed as a periodic structure in Wavelet-coefficients.
一般社団法人日本機械学会, 2012年11月16日, 流体工学部門講演会講演論文集, 2012, 413 - 414, 日本語研究発表ペーパー・要旨(国際会議)
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Control of aggregation/dispersion behavior of fine particles in a suspension is important to improve characteristics of complex materials. The dispersion behavior of fine particles in a suspension was observed and analyzed in a flow across sudden contraction in a microchannel. The dispersed particle and media of the suspension were polystyrene (diameter: 3:5 μm) and 27:0 wt% aqueous glycerol solution. The volume fraction was 0.02. The suspension was introduced to the microchannel using syringe pump. The velocity and dispersion behavior of fine particles of the suspension were determined in the PIV and image analysis. As a result, the velocity profile was fully developed at x/H = 0:23. The profile of the mean number of particles in a cluster at x/H = 0:24 was equal to the profile at upper stream. At x/H = 0:74, the mean cluster size was smaller than that at x/H = 0:24 It indicates a difference in the entrance region of the velocity field and aggregation/dispersion characteristics.
一般社団法人日本機械学会, 2015年11月07日, 流体工学部門講演会講演論文集, 2015, "0109 - 1"-"0109-2", 日本語Instability characteristics observed in a micro-cavity swept by a visco-elastic fluid has been investigated. Surfactant solution used as a viscoelastic fluid was inserted in a micro-cavity whose length, depth and wide low path were set constant at 1, 0.2 and 0.4 mm, respectively. The time variation of the tonguing motion of the separation bubble formed in the downstream region in the cavity was measured when the Reynolds number defined with water viscosity, cavity depth and the mean velocity in a narrow flow path was change in three steps: 1, 5 and 20. From the results, it was found that the fluctuation time scale is from 1.9 to 4.5 s, which is located between the middle and longest relaxation times. It was also found that the time scale does not depend on the Reynolds number.
一般社団法人日本機械学会, 2015年11月07日, 流体工学部門講演会講演論文集, 2015, "0110 - 1"-"0110-2", 日本語Experimental study on the contribution from the surfactant structure to the shear stress characteristics of drag-reducing cationic surfactant solution has been performed. The contributions from each structure were estimated while the surfactant concentration and the counter-ion molar ratio to the surfactants were widely changed. From the results, it was found that the structure having shortest relaxation time well corresponds to the shear stress characteristics. Form the comparison with the drag reduction occurrence map, the shortest relaxation structure was concluded to be the main cause of drag reduction occurrence.
一般社団法人日本機械学会, 2009年11月06日, 流体工学部門講演会講演論文集, 2009, 217 - 218, 日本語学術書
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口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
ポスター発表
ポスター発表
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
[招待有り]
口頭発表(招待・特別)
[招待有り]
口頭発表(招待・特別)
口頭発表(一般)
口頭発表(招待・特別)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
ポスター発表
ポスター発表
ポスター発表
ポスター発表
口頭発表(一般)
口頭発表(一般)
ポスター発表
口頭発表(一般)
口頭発表(一般)
ポスター発表
ポスター発表
ポスター発表
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
[招待有り]
口頭発表(招待・特別)
口頭発表(一般)
口頭発表(一般)
ポスター発表
口頭発表(一般)
ポスター発表
口頭発表(一般)
ポスター発表
[招待有り]
口頭発表(招待・特別)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
[招待有り]
口頭発表(招待・特別)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
ポスター発表
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(招待・特別)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(招待・特別)
口頭発表(一般)
口頭発表(一般)
ポスター発表
口頭発表(一般)
口頭発表(一般)
ポスター発表
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
[招待有り]
口頭発表(招待・特別)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(招待・特別)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
ポスター発表
ポスター発表
ポスター発表
ポスター発表
ポスター発表
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(招待・特別)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
ポスター発表
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
ポスター発表
ポスター発表
ポスター発表
ポスター発表
ポスター発表
ポスター発表
ポスター発表
ポスター発表
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
ポスター発表
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
ポスター発表
ポスター発表
口頭発表(招待・特別)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(招待・特別)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
口頭発表(一般)
[招待有り]
口頭発表(基調)
ポスター発表
ポスター発表
口頭発表(一般)
日本潜熱工学研究会
2012年01月 - 現在西日本乱流研究会
1999年04月 - 現在日本冷凍空調学会
1999年04月 - 現在日本粉体工学会
1998年04月 - 現在日本流体力学会
1998年04月 - 現在日本レオロジー学会
1997年04月 - 現在化学工学会
1997年04月 - 現在日本原子力学会
1991年04月 - 現在日本機械学会
1987年04月 - 現在日本伝熱学会
1987年04月 - 現在競争的資金
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リポソームの製造方法
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