KAGAKU KOGAKU RONBUNSHU
Online ISSN : 1349-9203
Print ISSN : 0386-216X
ISSN-L : 0386-216X
Volume 34 , Issue 6
Showing 1-10 articles out of 10 articles from the selected issue
Transport Phenomena and Fluid Engineering
  • Kenji Kubo, Katsutoshi Shoji, Hiroshi Suzuki
    Type: Research Paper
    Subject area: Transport Phenomena and Fluid Engineering
    2008 Volume 34 Issue 6 Pages 545-550
    Published: November 20, 2008
    Released: December 03, 2008
    JOURNALS RESTRICTED ACCESS
    The dispersion mechanism of emulsion in a static mixer, “Bunsankun”, by a disk-type element was made clear and its characteristics were investigated. The static mixer is a compact mixer that can create emulsion of any required size in the range of 1–600 μm by changing the flow velocity and the hole diameter of element. The static mixer disperses emulsions by repetition of division, combination, shearing and cavitation. The relations of pressure drop and flow velocity, emulsion size and flow velocity were expressed by experimental equations. The static mixer can create excellent emulsions.
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  • Noboru Kamei, Yoshihito Kato, Yutaka Tada, Takaomi Murai, Junichi Ando
    Type: Research Paper
    Subject area: Transport Phenomena and Fluid Engineering
    2008 Volume 34 Issue 6 Pages 551-556
    Published: November 20, 2008
    Released: December 03, 2008
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    Particle dispersion in turbulent agitated vessels with some kind of impellers was studied by an ion exchanged resin method. It was found that the apparent mass transfer coefficient with rotational speed less than the critical rotational speed for just completely suspension were correlated with Pv (b/D) , and that Pv at the critical rotational speed for just completely suspension was obtained. Although it is a radial flow impeller is not suitable for particle dispersion, the good particle dispersion condition was obtained by adjusting the impeller position in the vessel properly.
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  • Masafumi Mochizuki, Hiroyuki Sato, Yuki Doida, Yasuharu Saita, Takashi ...
    Type: Research Paper
    Subject area: Transport Phenomena and Fluid Engineering
    2008 Volume 34 Issue 6 Pages 557-561
    Published: November 20, 2008
    Released: December 03, 2008
    JOURNALS FREE ACCESS
    A new technique using a small pressure sensor was developed to measure the pressure distribution on the blade surfaces of a turbine in an aerated vessel. The following points were revealed.
    (1) When gas cavities were formed behind the blades, the pressure over the back surface of the blades rose, and the pressure fluctuation was reduced in comparison with ungassed conditions.
    (2) Most of the reduction in power consumption when gas was sparged into an agitator at a given speed was due to a decrease in form drag of the impeller.
    (3) The data on pressure on a blade surface were applicable to the design of a high performance impeller.
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  • Yoshihito Kato, Yutaka Tada, Hiromu Harada, Yuichiro Nagatsu, Tetsuji ...
    Type: Note
    Subject area: Transport Phenomena and Fluid Engineering
    2008 Volume 34 Issue 6 Pages 562-565
    Published: November 20, 2008
    Released: December 03, 2008
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    The effects of the vortex ring on the mixing performance have been studied. The velocity of vortex ring that generated from a circular pipe, did not decrease in a vessel. The mixing time with vortex rings was smaller than that with a jet mixer under the same average flow rate. It was found experimentally that the vortex ring promoted the liquid mixing.
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Thermal Engineering
  • Makoto Igarashi, Shogo Tamaki, Yuuko Fujii, Yohsuke Matsushita, Hideyu ...
    Type: Research Paper
    Subject area: Thermal Engineering
    2008 Volume 34 Issue 6 Pages 566-570
    Published: November 20, 2008
    Released: December 03, 2008
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    The performance of a refrigeration cycle with carbon dioxide was experimentally investigated. The effects of mass flow rate of carbon dioxide, higher side pressure and refrigerant mass on the cooling coefficient of performance, cooling capacity and compressor work were examined. Then cooling coefficient of performance decreased and cooling capacity increased with an increase in mass flow rate of carbon dioxide. The cooling coefficient of performance had maximum value at a gas cooler outlet pressure of around 8.3 MPa regardless of compressor speed. A higher cooling coefficient of performance will be obtained by controlling gas cooler outlet pressure. Furthermore, compressor work increased with an increase in gas cooler outlet pressure regardless of refrigerant mass. The cooling coefficient of performance and cooling capacity increased with an increase in refrigerant mass.
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Chemical Reaction Engineering
  • Taketoshi Kurooka, Ryohei Yamazaki, Guiqing Liu
    Type: Research Paper
    Subject area: Chemical Reaction Engineering
    2008 Volume 34 Issue 6 Pages 571-579
    Published: November 20, 2008
    Released: December 03, 2008
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    Using Geldart's A-particle, the local variables of bubble properties including bubble frequency, fraction, size, rising velocity and visible bubble flow rate were measured in fine particle fluidized beds and theoretically discussed. Basing on the experimental results, a model was newly proposed for estimating the cross sectional-averaged values of bubble variables and the validity of the model were examined. The following were obtained.
    (1) The radial distributions of local bubble frequency and fraction are parabolic.
    (2) The radial distributions of local bubble chord length and rising velocity are almost flat.
    (3) The cross sectional-averaged values of visible bubble flow rate are about 70% of superficial gas velocity.
    (4) The observed cross sectional values of bubble variables agree well with the values calculated using the model proposed in this work. In addition, the model is also capable for estimating the size of bubbles in fluidized beds where the splitting of bubbles is not observed or can be neglected.
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Materials Engineering and Interfacial Phenomena
  • Takuya Imaki, Koji Mine, Hedeaki Kubo, Yoshiyuki Sato, Hiroshi Inomata
    Type: Research Paper
    Subject area: Materials Engineering and Interfacial Phenomena
    2008 Volume 34 Issue 6 Pages 580-586
    Published: November 20, 2008
    Released: December 03, 2008
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    Sphingolipid E (SLE) is a synthesized sphingolipid on the model of ceramide. SLE plate particles could be produced via crystallization by cooling the SLE melt solution in the presence of supercritical carbon dioxide and were obtained as fine powder after depressurization. It was estimated that the particle aggregation was reduced by depressurization together with cooling. The obtained SLE plate particle powder contains no residual solvent and is pleasant to the touch, indicating its potential for use in cosmetics with moisturizing effect.
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  • Kazuhiro Oki, Yuji Nagasaka
    Type: Research Paper
    Subject area: Materials Engineering and Interfacial Phenomena
    2008 Volume 34 Issue 6 Pages 587-593
    Published: November 20, 2008
    Released: December 03, 2008
    JOURNALS FREE ACCESS
    Ripplon surface laser-light scattering (the ripplon method) is a powerful and extremely appealing measurement tool for measuring surface properties, because it can quickly extract information about the surface of liquid films without contact and without the need for external disturbances such as induced excitations. In this research, a newly developed ripplon surface laser-light scattering measurement instrument was used to conduct measurements of the surface properties of cellulose acetate butyrate (CAB) polymer dissolved in methyl ethyl ketone (MEK) with the goal of measuring a polymer–organic solvent system that is widely used in the fabrication of functional films and other areas. Although no variation in surface tension with polymer concentration was observed by a contact measurement method (the Wilhelmy Plate method), the surface tension decreased as the polymer concentration increased when observed by the ripplon method in the frequency range of several tens of kHz. When the model of adsorption of polymer onto the liquid film surface was examined in the measured ripplon frequency range, it was inferred that the ripplon wave modulation speed was significantly greater than the time required for the CAB polymer to adsorb onto and desorb from the liquid film surface. Consequently, there was not enough time for the CAB polymer to adsorb onto and desorb from the surface, and the film behaved like an insoluble molecular film. It is therefore clear that differences in the amount of polymer adsorbed onto a liquid film surface due to differences in the CAB polymer concentration and molecular mass correspond to a reduction in surface tension and are observed as changes in surface elasticity. By focusing on this variation in surface elasticity, it is expected that this method can be used as a new tool for measuring and evaluating the ease of adsorption and desorption of polymer onto the liquid film surface of low density polymer–organic solvent systems having low surface tension and low viscosity, which had previously been difficult to measure.
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  • Izumi Taniguchi, Taro Yano, Lianqi Zhang
    Type: Note
    Subject area: Materials Engineering and Interfacial Phenomena
    2008 Volume 34 Issue 6 Pages 594-597
    Published: November 20, 2008
    Released: December 03, 2008
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    Lithium manganese oxide (LiMn2O4) powders have been synthesized by spray yrolysis method from the precursor solution; LiNO3 and Mn(NO3)2·6H2O were stoichiometrically dissolved into distilled water. The as-prepared powders exhibited a pure cubic spinel structure in the X-ray diffraction (XRD) patterns for various precursor concentrations ranging from 0.045 to 0.9 mol/L. While the geometric mean diameter of LiMn2O4 prepared at 0.045 mol/L was 0.57 μm, the one prepared at 0.9 mol/L was 1.11 μm.
    The as-prepared samples were used as cathode active materials for lithium batteries. Test experiments in the electrochemical cell Li|1 M LiClO4 in EC : DEC=1 : 1|LiMn2O4 were carried out for various charge-discharge rates at room temperature. The discharge capacity and rate capability of as-prepared samples were strongly affected by the particle size of LiMn2O4.
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Environment
  • Shohichi Osada, Hiroki Kageyama, Daisuke Shima, Hitoki Matsuda
    Type: Research Paper
    Subject area: Environment
    2008 Volume 34 Issue 6 Pages 598-605
    Published: November 20, 2008
    Released: December 03, 2008
    JOURNALS RESTRICTED ACCESS
    A shaft-type furnace model, in which the furnace column was divided into multi cells, was designed and incorporated with equilibrium reaction calculation software for studying the volatilization behaviors of low-boiling-point metals of Pb and Na, K during gasification and melting process of municipal solid wastes in a shaft type furnace. The volatilization behaviors of Na, K and Pb were discussed by comparing the results on volatilization of Na, K and Pb derived by the equilibrium calculation with the data obtained from an actual operation unit.
    As a result, it was found that Na, K and Pb were volatilized mainly as chloride forms in the temperature range up to approximately 1173 K and were volatilized as metallic forms with a further rise in temperature. It was also found that the chloride volatilization ratio of Pb increased with an increase in chloride content, and that the volatilization of metallic Pb became dominant when the oxygen partial pressure was below 1×10−7 MPa. From the results of a pilot-plant and a laboratory-scale melting tests, it was recognized that Pb concentration in slag decreased as the oxygen partial pressure decreased, and that the remaining Pb ratio in slag decreased as the basicity of slag increased. These results on volatilization behavior of Pb were well represented by the equilibrium calculations using the proposed shaft type furnace model.
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