KAGAKU KOGAKU RONBUNSHU
Online ISSN : 1349-9203
Print ISSN : 0386-216X
ISSN-L : 0386-216X
Volume 11 , Issue 5
Showing 1-16 articles out of 16 articles from the selected issue
  • Masafumi Kuriyama, Masayuki Toda, Eiji Harada, Hirotaka Konno
    1985 Volume 11 Issue 5 Pages 497-501
    Published: September 10, 1985
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    An experimental study was made of heat transfer from rotating spheres with vibration in air flow. Heat transfer coefficients of the spheres in this kind of combined process could be estimated by use of the heat transfer correlations obtained for vibrating spheres, rotating spheres and spheres in air flow.
    On the basis of the experimental results, heat transfer between solid particles and fluid in gas-solid two-phase flow was studied. It was concluded that the effects of air velocity fluctuation and rotational movement of particles on the heat transfer should not be neglected in gas-solid two-phase flow.
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  • Satoshi Ohshima, Kazuo Shimada, Toshiichi Takematsu, Morio Suzuki, Mot ...
    1985 Volume 11 Issue 5 Pages 502-507
    Published: September 10, 1985
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    To clarify the hydrodynamic behavior of the coal liquefaction system, gas holdup and gas-liquid mass transfer coefficients in hydrogen-coal-derived liquid and hydrogen-hydrogenated anthracene oil systems were measured under conditions similar to those for coal liquefaction reaction in a C. S. T. reactor with self-inducing type stirrer, which has a hydro-dynamic behavior similar to that of a large-scale coal liquefaction reactor, and the following results were obtained.
    1. Minimum stirrer speed at onset of gas induction was not affected by pressure, and was well correlated by the equation of Sawant and Joshi.
    2. Gas holdup increased with increasing rotational speed of stirrer and temperature, but was not affected by pressure. This suggested that gas holdup was affected by liquid viscosity, which varied with temperature.
    3. Gas-liquid mass transfer coefficients at the free surface of the C. S. T. reactor increased with increasing system temperature, and fairly well agreed with those of previous workers using organic solvents as liquid phase.
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  • Hiroyuki Kawasaki, Hisaya Tanaka
    1985 Volume 11 Issue 5 Pages 508-514
    Published: September 10, 1985
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Mass transfer coefficients kl between wall and fluid of air-water upward cocurrent flow were obtained by measuring the dissolution rate of solid wall in vertical tubes of 0.95, 1.6, and 2.8 cm diameter. The flow covered the regions of forced and free rising of bubble in regard to the flow parameter F=ub0/ (ug0+ul0). kl in each region was correlated as follows, respectively.
    In the former region :
    Sh=0.34Re3/5Sc1/3 (D/L) 1/3
    In the latter :
    Sh=0.72Reb3/5Sc1/3 (D/L) 1/3
    In these relations, dimensionless groups were defined as follows : Sh=klD/Dl, Rem (ug0+ul0) Dl, Scl/ (ρmDl), Rebm {(ρlm) /ρm} 1/2ub0Dl and ρml (1-φ).
    Over these flow regions, assuming additivity of both Reynolds numbers, the following correlation was obtained.
    Sh=0.34(1+12K)3/10Re3/5Sc1/3 (D/L) 1/3
    where K= [{(ρlm) /ρm} 1/2·F] 2.
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  • Masanao Imai, Shintaro Furusaki
    1985 Volume 11 Issue 5 Pages 515-519
    Published: September 10, 1985
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The extraction equilibrium of lanthanum by D2EHPA was measured at 298K, using an industrial-grade diluent, SHELLSOL®-K. The composition of the organic phase species is LaR3·3HR, which is identical to that obtained for the case of reagent-grade diluents and is reported in the literature. The aqueous distribution of D2EHPA was also measured, and the equilibrium constants of this extractant were determined. Addition of the surfactant, Span 80®, to the present system did not change the extraction constant for lanthanum.
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  • Yoichi Chiba, Mutsumi Suzuki, Shigemori Ohtani
    1985 Volume 11 Issue 5 Pages 520-527
    Published: September 10, 1985
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    To investigate the sweeping effect of falling drops in dropwise condensation of steam, condensate liquid specially prepared from steam was supplied to the top end of a vertical condensing surface from nozzles. Heat transfer rate was measured and the configuration of the surface was photographed. It was found that the heat transfer coefficient increased with increasing supplied drops, reached a maximum and then decreased little by little. Heat transfer coefficient, however, never fell to that of the non-supplied (usual dropwise condensing) condition.
    To search the effect of the moving of drops on heat transfer, heat transfer rate with surface condition changing with time was calculated by a two-dimensional model. From calculation, it was found that the heat transfer rate increased with the changing speed of the surface condition. In dropwise condensation the motion of drops itself was considered to contribute to the increase of heat transfer rate.
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  • Naotake Katoh, Takahiro Yoshida, Kohichi Nakamichi
    1985 Volume 11 Issue 5 Pages 528-533
    Published: September 10, 1985
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    It is difficult for a simple PID algorithm to control a xylene isomerization reactor for which the dynamic parameters vary with catalyst decay. By use of the model reference adaptive system (MRAS), recently developed in the control engineering field, a reactor control experiment was carried out. The effectiveness of MRAS combined with PID algorithm was demonstrated by this experiment.
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  • Hiroo Tsujikawa, Toshio Osawa, Hakuai Inoue
    1985 Volume 11 Issue 5 Pages 534-541
    Published: September 10, 1985
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Benzene-nitrogen gas mixture was permeated from outside to inside of a porous Vycor Glass pipe of 17 mm outer diameter, 1.4 mm thickness and 50 mm length. Fluctuations of the permeability data of benzene were minimized by treatment based on a model in which the uptake side was in piston flow with axial mixing.
    The permeabilities of benzene were found to be of the Arrhenius type to temperature and were correlated well with the ratio of the mean benzene pressure of the system to the vapour pressure of saturation.
    The permeability of nitrogen in the presence of benzene vapour could be estimated well by Okazaki's equation under the condition where benzene pressure is less than 0.4 of the saturation. The boundary corresponds to the capillary condensation pressure into the pores of the Vycor Glass.
    Under higher pressure of benzene the permeability of nitrogen deviated from the equation and decreased more than did the estimation.
    The separation factor of benzene to nitrogen increased with the pressure of benzene and reached about 3000. A simple model for estimation of the permeation rate under capillary condensation was proposed.
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  • Hitoki Matsuda, Takashi Ishizu, Soo Kag Lee, Masanobu Hasatani
    1985 Volume 11 Issue 5 Pages 542-548
    Published: September 10, 1985
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The following reversible thermochemical reaction involving both an exothermic and an endothermic process was studied from the fundamental point of view of reaction kinetics in order to apply this reaction system to thermal energy storage by means of chemical reaction.
    CaO + H2O _??_ Ca (OH) 2 + 104.2kJ/mol
    Both the hydration of CaO and the dehydration of Ca (OH) 2 were studied in the chemical reaction control region by a thermogravimetric analysis (TGA) with the reactant solid particle size under 5 μm, the reaction temperature 356.2-723.2 K and the steam concentration 1.5-15.7vol%.
    Reaction parameters such as rate constant, activation energy and reaction order of the individual reaction were determined by the obtained TGA experimental results on the basis of the Grain Model by assuming the presence of a reaction intermediate, CaO · H2O*, in the course of reaction.
    It was found that the reaction orders of both the hydration of CaO and the dehydration of Ca (OH) 2 with respect to the concentration of solid reactant and the partial pressure of steam were 1.0. Further, it was found that the overall reaction rate constants of both reactions could be expressed in non-linear form, which gave a maximum value at about 473.2 K for the hydration of CaO.
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  • Mutsuo Sando, Atsushi Fujii, Tetsuo Noguchi, Shigeki Toyama
    1985 Volume 11 Issue 5 Pages 549-554
    Published: September 10, 1985
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    A formula to calculate the instantaneous efficiency of an evacuated tubular collector which has flat absorber plates in glass tubes and a white plate with diffuse reflection beneath tubes is derived, considering the dependency of effective transmission-absorption factor (τα) e on the direction of incident solar radiation. The curve of efficiency characteristics by theoretical calculation and that by experimental measurements have almost the same inclination, and the validity of the theoretical formula on heat losses from the collector is proved. The calculated efficiency ηth and the measured efficiency ηm show almost the same effect by the change of direction of incident solar radiation, so that dependency of theoretically calculated (τα) e on the direction of incident radiation is similar to that of a real collector.
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  • Yukinari Sato, Kazuo Yamamoto
    1985 Volume 11 Issue 5 Pages 555-562
    Published: September 10, 1985
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Measurements for Lagrangian characteristics of turbulence, including mean-square value of lateral diffusion from a point source Y2, rms value of fluctuating velocity v', integral scale corresponding to mixing length of eddy ΛL, velocity auto-correlation coefficient RL (τ), etc., were made in isotropic turbulent flow behind a grid, with the tracer-particle tracking method proposed by present authors previously.
    Comparison of these Lagrangian data with Eulerian integral scale Λf and the double velocity correlation coefficient f (r) led to the following results :
    1) For turbulent Reynolds number of Rλ=20 to 70, β (=ΛLf) is within the values of 0.6 to 0.3, becoming lower as Rλ increases.
    2) Distribution of RL against τ is fairly similar to that of f against βr/v'.
    Further, it was confirmed by both theoretical analysis and experiments that the growth of Y2 (t) was weakened by turbulent energy decay, and remarkably so for long diffusion times.
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  • Katsumi Nakagawa
    1985 Volume 11 Issue 5 Pages 563-566
    Published: September 10, 1985
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The effect of interbubble distance on natural frequencies of two bubbles in water was experimentally investigated by the floating bubble method and the pulse response method of sound.
    The frequency F affected by the interaction of two bubbles was measured over the range 0.6 to 29.3 of L/D0, where L and D0 are distance of the bubble surface to surface and the bubble equivalent diameter, respectively.
    As the value of L/D0 grew larger than about 3, there was no effect of L/D0 on F, while as it grew smaller than about 3, a small effect was found.
    In addition, these experimental results show good agreement with Shima's theory of the natural frequency of two spherical bubbles oscillating in water.
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  • Tsutomu Aragaki, Kazunori Murase, Hassan Mohamed Salah, Katsumori Nagu ...
    1985 Volume 11 Issue 5 Pages 567-573
    Published: September 10, 1985
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Laminar steady-state film flow in an open channel formed by fine parallel wires attached to the lower or upper side of an inclined plate were analyzed numerically by using the Ritz finite element method. The shapes of meniscus profiles, required for the boundary condition, were decided theoretically on the basis of force balance between capillary force and pressure gap at the interface.
    The results indicate that there exist three types of velocity profile, depending mainly on channel width and film thickness. The location of the higher-velocity region differs from one case to another. Drag coefficient CD and Re can be related as CD =K/Re where K ranges from 1.7 to 2.8. The volumetric flow rate for upward-facing meniscus flow is compared with that for downward-facing flow. The former case shows higher flow rate than the latter, and the difference becomes remarkable for a wider shallow channel. It is found that the meniscus can be taken as circular for the case of a narrow, thick film, but this assumption cannot be applied to a wider shallow channel.
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  • Tsuneyuki Sato, Hidenobu Tsutsumi, Toshikuni Yonemoto, Teiriki Tadaki
    1985 Volume 11 Issue 5 Pages 574-580
    Published: September 10, 1985
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The phenomena of physical absorption of a concentrated gas component in a wetted-wall column operated in laminar regime were simulated by solving the Navier-Stokes and diffusion equations with a finite difference technique. For simultaneous analyses of gas and liquid phases, which have quite different Schmidt numbers, a finer-mesh width was used in the gas phase adjacent to the gas-liquid interface. In this way, the computation time was significantly reduced.
    Experimental study of the absorption of acetone vapor into pure water was carried out to check the theoretical analysis.
    It was found that the method of analysis used in this study can express the experimental results accurately and allows us to study various factors affecting the absorption rate, such as feed gas concentration, variation of flow rate of gas and liquid phases and gravitational acceleration.
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  • Kenji Takeshita, Asashi Kitamoto
    1985 Volume 11 Issue 5 Pages 581-588
    Published: September 10, 1985
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The performance of isotope separation of carbon-13 by chemical exchange between carbon dioxide and carbamic acid was studied. The working fluid used in the study was a solution of DNBA, (C4H9) 2NH and n-octane mixture. Factors related to the isotope exchange rate were measured, such as the absorption rate of carbon dioxide into the solution of DNBA and n-octane, the isotope exchange rate and the separation factor in the reaction between CO2 and carbamic acid.
    The absorption of CO2 into the working fluid was the sum of chemical absorption by DNBA and physical absorption by n-octane. The absorption of carbon dioxide into the working fluid was negligible at temperatures over 90°C, but increased gradually at lower temperatures. Carbon dioxide was absorbed into DNBA by chemical absorption, and DNBA was converted to carbamic acid by the reaction. The reaction for synthesis and decomposition of carbamic acid was reversible.
    The separation factor in equilibrium reached a large value at lower temperatures.
    The isotope exchange rate between gas and liquid was proportional to the product of the concentration of carbamic acid and the concentration of CO2 by physical absorption.
    The isotope separation of carbon by chemical exchange reaction is better operated under the conditions of lower temperature and higher pressure.
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  • Kunihisa Osasa, Masao Sambuichi, Hideo Nakakura
    1985 Volume 11 Issue 5 Pages 589-595
    Published: September 10, 1985
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Flocculation-sedimentation tests by polymeric flocculant addition were carried out in a reactor of large capacity (10 liters) with a gate-type paddle. The effects of solids concentration, flocculant dosage and flocculation mechanism on the optimum mixing conditions were investigated experimentally. Systems of kaolin-cationic polymer and of water works sludge-nonionic polymer were used; flocculation mechanisms were described by the surface charge neutralization and bridge models, respectively. The flocculation effect was assessed in terms of residual turbidity. The following points were determined experimentally. (1) The optimum rapid mixing conditions were given by the root mean square velocity gradient, G=610s-1, and the flocculation period, T= 90 s. (2) The slow mixing conditions could be assessed by the product of G and T. (3) The optimum value of GT was inversely proportional to flocculant dosage per unit mass of solids. This relation was well confirmed for both systems of solids and flocculant in the range of solids concentration from 100 to 500 mg/l.
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  • Akira Yasunishi, Yutaka Tada, Manabu Yamaguchi, Atsushi Kobayashi, Tak ...
    1985 Volume 11 Issue 5 Pages 596-619
    Published: September 10, 1985
    Released: November 12, 2009
    JOURNALS FREE ACCESS
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