JOURNAL OF CHEMICAL ENGINEERING OF JAPAN
Print ISSN : 0021-9592
Volume 9 , Issue 6
Showing 1-15 articles out of 15 articles from the selected issue
  • TOSHIRO MARUYAMA, TOSHIAKI KURIBAYASHI, TOKURO MIZUSHINA
    1976 Volume 9 Issue 6 Pages 431-439
    Published: December 31, 1976
    Released: March 29, 2006
    JOURNALS FREE ACCESS
    The dynamic structure of turbulence in transient pipe flows was studied experimentally. Two types of stepwise change in the flow rate of a fully developed pipe flow showed apparently different behaviours in this turbulence. With a stepwise increase in the flow rate, the dominant feature was the generation and propagation of a new turbulence. With a stepwise decrease in the flow rate the dominant feature was the decay of an old turbulence.
    However, a comparison of these two types of stepwise change indicates a coherent structure in the propagation of a new turbulence in both transient pipe flows. The propagation time of new turbulence is determined by the condition at its generation. Moreover, this coherent character is also applicable to the propagation of an old turbulence, and the beginning of the decay of the old turbulence is predicted by the propagation time in initial steady state. On the basis of these facts the dynamic behaviours of turbulence in both these types of transient flow are interpreted consistently.
    For the decay of the old turbulence, the ''linear'' decay law is applicable and the decay rate is governed by the flow condition during decay, although the propagation time is not affected by the transient flow.
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  • SUMITOSHI OGATA, TAKASHI KAWASHIMA, OSAMU NAKAYA, HISASHI SHINOHARA
    1976 Volume 9 Issue 6 Pages 440-444
    Published: December 31, 1976
    Released: March 29, 2006
    JOURNALS FREE ACCESS
    The behavior of the charged drop issuing from metal capillaries was investigated.
    The dripping frequency of conductive liquids increased with increasing applied D.C. volatge, while the diameter of the dripping drop gradually decreased up to from 1.5 to 2.0 times the outside diameter of the capillary and eventually burst.
    It was found that there is a critical drop diameter correlating with the minimum spraying voltage.
    Theoretical approximate consideration of the critical drop diameter was further examined. The experimental data were rearranged by the modified Bond number derived theoretically and showing slight dependence on it.
    The charge-to-mass ratio of the dripping drop was measured for various voltage levels, so that the specific charge of the critical drop was found to be about one-half a fully charged drop, known as the Rayleigh''s limit.
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  • AKTHIRO YAMANAKA, TOYOKI YUKI, NOBUO MITSUISHI
    1976 Volume 9 Issue 6 Pages 445-449
    Published: December 31, 1976
    Released: March 29, 2006
    JOURNALS FREE ACCESS
    Experiments on heat transfer from spheres to liquids have been carried out in the range of 2.0×10-4<Re<900, 7.0<Pr<2.4×104 and 5.7×10-3<Gr<107 for combined convection. A sphere, 46.03 mm in diameter, composed of eleven copper segments, and two brass spheres (19.03 and 9.534 mm in diameter) have been used. Test liquids used were 0.96%, 2.59%, 2.62% CMC aqueous sol. and 0.69%, 0.97%, 1.07% MC (methylcellulose) aqueous sol. The experimental data are summarized by the following relation:
    Num-2 = [{(126Re+57Re3/2)Pr1/3/(1+52Re1/2+100Re)}3/2 + (0.44Gr1/4Pr1/4)3/2]2/3bs)1/4 where μb is the viscosity at the bulk liquid temperature tb and μs is the viscosity at the sphere surface temperature ts. This equation has been shown to represent measured values of Num within an average deviation of 13.6 per cent.
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  • TOKURO MIZUSHINA, TOSHITATSU MATSUMOTO, SHIGEYUKI YONEDA
    1976 Volume 9 Issue 6 Pages 450-457
    Published: December 31, 1976
    Released: March 29, 2006
    JOURNALS FREE ACCESS
    This paper presents the results of analytical and experimental investigations of the local behaviour of turbulent heat and momentum transfer in a hot air flow through a cooled circular tube with a steep radial temperature gradient. It is concluded that in the turbulent core region the profiles of mixing length are not different from isothermal ones. It is presumed that the damping of mixing length near the wall is expressed by extending the Van Driest model to non-isothermal flow of gas. It is shown that the analytical prediction correlates the results of the measurements satisfactorily, and that in the cooling turbulent gas flow of low Reynolds number the deviations of the Nusselt number and friction factor from isothermal ones are negligibly small when they are correlated by using physical properties at bulk temperature.
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  • YOSHISHIGE HAYASHI, Em HIRAI, NORITOSHI ITO
    1976 Volume 9 Issue 6 Pages 458-463
    Published: December 31, 1976
    Released: March 29, 2006
    JOURNALS FREE ACCESS
    A theoretical analysis of crossflow cooling tower was studied under conditions such that the change in the water flow rate due to vaporization is not negligible throughout the apparatus and a method of numerical calculation to estimate both the enthalpy of air and temperature of water in a tower was derived, and by applying this method, a calculation method of overall volumetric enthalpy transfer coefficients and the effect of operating conditions on the enthalpy arrival factor, which expresses the cooling effect, were investigated. In addition, the deviation in the tower volume between the case of taking into account and not taking into account the change in the water flow rate in crossflow cooling towers was discussed under the same operating conditions.
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  • TAHEI TOMIDA, MICHIRU YOSHIDA, TATSUYA OKAZAKI
    1976 Volume 9 Issue 6 Pages 464-468
    Published: December 31, 1976
    Released: March 29, 2006
    JOURNALS FREE ACCESS
    Liquid-side volumetric mass transfer coefficients were obtained in vertical upward two-phase flow by desorbing carbon dioxide from liquid phases of water, aqueous glycerine and malt honey. Measurements were made mainly in the froth and the wavy annular flow using tubes of 10, 18 and 25 mm i.d.
    A correlation for the volumetric mass transfer coefficient was developed semi-empirically based on the analogy between mass and momentum transfer. Experimental data were correlated by two equations in dimensionless form corresponding to the two flow mechanisms of pseudo-laminar flow and turbulent flow.
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  • KOEI KAWAKAMI, KOICHIRO KUSUNOKI
    1976 Volume 9 Issue 6 Pages 469-474
    Published: December 31, 1976
    Released: March 29, 2006
    JOURNALS FREE ACCESS
    The liquid-phase consecutive hydrogenations of phenylacetylene are investigated in the presence of a 0.5% Pt-Al2O3 catalyst. Experiments are performed in a stirred reactor with basket impellers in which the catalyst pellets are held, and a stirred slurry reactor in which the finely powdered pellets are suspended. The intrinsic kinetic equations are derived empirically from the rate measurements with the powdered catalysts. Under the intrinsic kinetic limitation, the intrinsic yield of styrene is independent of both the initial concentration of phenylacetylene and the hydrogen concentration. With the catalyst pellets the hydrogenation rates and the yields are significantly influenced by the intraparticle diffusion. The yield in the regime of the diffusional limitation is reduced below the intrinsic yield, but it is restored up to the level of the intrinsic yield with increasing initial concentration of phenylacetylene and/or decreasing hydrogen concentration.
    The intraparticle diffusion effects on the hydrogenations are modeled theoretically and solved numerically. By the favorable assessment of the effective diffusivities of the reaction species, the calculated conversion and yield are in good agreement with the experimental results.
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  • KOEI KAWAKAMI, YASUYUKI OHGI, KOICHIRO KUSUNOKI
    1976 Volume 9 Issue 6 Pages 475-480
    Published: December 31, 1976
    Released: March 29, 2006
    JOURNALS FREE ACCESS
    The hydrogenation of ethylene and propylene was studied in the presence of a 5 % Pt/carbon catalyst suspended in water. In the hydrogenation of the respective olefin, the rate-controlling steps affecting the overall reaction rate were first examined. As for the results, the hydrogenation rates were found to be predominantly controlled by the mass transfer of olefin from the gas phase to the catalyst particles in the region of excess hydrogen, while in the region of excess olefin they were influenced not only by the mass transfer but also by the combination of the chemical reaction and the pore diffusion. For the latter region, an intrinsic kinetic expression was derived assuming the adsorption of molecular hydrogen as the rate-determining step.
    For the competitive hydrogenation of both olefins, the selectivity, defined as the ratio of the reaction rate of propylene to that of ethylene, was examined on the basis of the results obtained in the hydrogenation of the individual olefin.
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  • EIICHI ONUMA
    1976 Volume 9 Issue 6 Pages 481-484
    Published: December 31, 1976
    Released: March 29, 2006
    JOURNALS FREE ACCESS
    A grinding system consisting of a ball mill and an imperfect classifier, whose performance characteristics include wide-range stochastic classification processes as well as partition phenomenon towards the coarser products, is analyzed by means of matrix simulation method.
    The analysis is principally aimed at the clarification of classifier performance on the steady-state flow-rate and also on the particle size distribution of fine products, under the prerequisite that the fraction of particles finer than a predetermined size should be kept constant by means of the adjustment of cut-size of classifier.
    From the results of analysis, some suggestions can be made on the optimization of operational or design variables. One of these is on the existence of optimum point of classifier-feed flowrate F and the effects of other variables on its location. To make steady-state flow-rate of fine products highest, it is recommended that the classifier should be operated so that the flow-rate of recirculating air in the classifier may be held constant at the maximum value, and F should be maintained constant at the optimum point.
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  • EIICHI ONUMA, NOBUYOSHI ASAI, GENJI JIMBO
    1976 Volume 9 Issue 6 Pages 485-488
    Published: December 31, 1976
    Released: March 29, 2006
    JOURNALS FREE ACCESS
    Though the locked-cycle test is often used for estimating the steady-state characteristics of a closed-circuit grinding system, few of these test results, especially when classification is not perfect, has been analyzed from the viewpoint of comminution kinetics.
    Moreover, with regard to the case that the cut-size of the classifier is so adjusted that a prerequisite condition on the size distribution of fine products may be satisfied, no one has investigated experimentally. In this paper, the results of locked-cycle grinding tests including the above mentioned cases are analyzed, and compared with the computer simulation data of steady-state characteristics of the corresponding closed-circuit continuous grinding system. The factors examined are grinding time and ratio of partition towards the coarser products of classifier. The analysis shows that the steady-state characteristics of a closed-circuit continuous grinding system can be estimated with reasonably high accuracy from the test data of corresponding locked-cycle grinding tests.
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  • MASABUMI NISHIKAWA, YUKIMICHI OKAMOTO, KENJI HASHIMOTO, SHINJI NAGATA
    1976 Volume 9 Issue 6 Pages 489-494
    Published: December 31, 1976
    Released: March 29, 2006
    JOURNALS FREE ACCESS
    Turbulence energy spectra were measured for longitudinal and lateral components of fluctuating velocity, in baffled mixing vessels keeping geometrical similarity, by using a hot-film anemometer. From the comparison of the spectra, it was confirmed that the turbulence in the impeller stream deviated largely from both homogeneity and isotropy, especially in the lower wave-number range. However, these deviations were so small for the turbulence in other regions that the assumption of local isotropy would be applicable and that the homogeneity was implied to exist in the higher wave-number range. Energy spectra normalized by microscale λ and fluctuating velocity component u''i showed good similarity and were not affected by location in the vessel, agitator speed and size of the mixing vessel. Then, effects on energy spectra by agitator speed and by the size were fairly represented by u''i and by λ respectively. The Kolmogoroff''s universal similarity of spectrum was not observed except in the very high wave-number range.
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  • B. S. CHANDAK, G. D. NAGESHWAR, P. S. MENE
    1976 Volume 9 Issue 6 Pages 495-498
    Published: December 31, 1976
    Released: March 29, 2006
    JOURNALS FREE ACCESS
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  • NOBUYUKI IMAISHI, MITSUNORI HOZAWA, KATSUHIKO FUJIKAWA
    1976 Volume 9 Issue 6 Pages 499-501
    Published: December 31, 1976
    Released: March 29, 2006
    JOURNALS FREE ACCESS
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  • HAKARU MITSUTAKE, MASASHI SAKAI
    1976 Volume 9 Issue 6 Pages 501-503
    Published: December 31, 1976
    Released: March 29, 2006
    JOURNALS FREE ACCESS
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  • SHUNTA TANAKA, YASUHIKO ARAI, SHOZABURO SAITO
    1976 Volume 9 Issue 6 Pages 504-507
    Published: December 31, 1976
    Released: March 29, 2006
    JOURNALS FREE ACCESS
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