KAGAKU KOGAKU RONBUNSHU
Online ISSN : 1349-9203
Print ISSN : 0386-216X
ISSN-L : 0386-216X
Volume 8 , Issue 2
Showing 1-24 articles out of 24 articles from the selected issue
  • Yosuke Kawashima, Masayoshi Nakagawa, Satoru Iuchi
    1982 Volume 8 Issue 2 Pages 109-114
    Published: March 10, 1982
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Characteristics of mixing due to confluent flow in a two-dimensional flow section of right-angled T type were experimentally obtained and the effects of sectional area ratio in and flow rate ratio Q1/Q3 on mixing were investigated (Q1 : upstream flow rate of main stream, Q3 downstream flow rate of main stream). Furthermore, the effects of confluent downstream flow on mixing were examined by comparing the experimental results in a confluent flow section with calculated results in a two-dimensional straight flow section. The results were as follows :
    The downstream length Le for complete mixing in a confluent flow section became considerably shorter than the calculated results Lc with increasing m and decreasing Q1/Q3 (Lc : downstream length required for complete mixing in a two-dimensional straight flow section).
    Le was expressed as a function of contraction coefficient Cc, m and Lc.
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  • Katsuhiro Nozawa
    1982 Volume 8 Issue 2 Pages 115-120
    Published: March 10, 1982
    Released: November 12, 2009
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    The fusion of horizontal cylindrical ice in jetted moist air is exprimentally observed. The relationship between mean NumH number and Re number, influenced by humidity, is described as the following experimental equation. NumH= AmHRen. The experimental value, when arranged, is constantly n=0.58. The modified humidity factor Amis described as the following equation. AmH =0.37+19H.
    The application region of humidity is from 0.005 to 0.02 kg H2O/kg dry air, and that of Re number is from 1, 500 to 120, 000.
    Other observations are made on some phenomena influenced by humidity.
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  • Takatoshi Miura, Hiroto Tajima, Kiyoshi Miura, Shigemori Ohtani
    1982 Volume 8 Issue 2 Pages 121-126
    Published: March 10, 1982
    Released: November 12, 2009
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    A hot wire method has long been successful for determining thermal conductivity of various materials. In this paper, a modified hot wire method is presented. It utilizes the principle of differential thermal analysis and permits the measurement of thermal conductivity under quasi-state heating conditions. Measurements are made for five kinds of pulverized coals at heating rate of 3°C/min from room temperature to 850°C. The measured thermal conductivities of coals are successfully correlated by the following equation : λeffcexp (A (θ-θc)), where θc is the temperature (450°C) defined as the transition point from low-temperature region to high-temperature region, λc is the effective thermal conductivity at θc, and A is the temperature coefficient in both regions. These parameters (θc, λc and A) are correlated with the fixed carbon content.
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  • Nobuyuki Imaishi, Yasuo Suzuki, Mitsunori Hozawa, Katsuhiko Fujinawa
    1982 Volume 8 Issue 2 Pages 127-135
    Published: March 10, 1982
    Released: November 12, 2009
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    By means of both linear-stability and non-linear numerical analyses, theoretical investigation was made of the initiation and growth of interfacial turbulence induced by Marangoni effect during gas-liquid mass transfer. The results were compared with previously reported results of mass transfer experiments in a liquid jet column and a wetted wall column.
    It was revealed that the stability limit of liquid layer against Marangoni effect during desorption of surface-active solute can be estimated correctly by application of the result of linear stability analysis, earlier reported by Brian, in which the stabilizing effect of the adsorption layer of the desorbing surface-active solute itself was taken into consideration. Although the time at which enhancement of mass transfer rate can be first detected was longer than the time predicted by linear stability analysis for the initiation of convection, the order of magnitude of this delay time was in accord with the result of the numerical analysis of unsteady, two-dimensional diffusion equation and Navier-Stokes equations.
    Numerical analysis clarified further details in :
    1) flow pattern and concentration profiles in liquid phase;
    2) relationship between liquid-phase mass transfer coefficient kL and elapsed time;
    3) effect of gas-phase mass transfer rate on the intensity of convection and on kLAgreement between calculated values of kL and those obtained by previous experiments was fairly good.
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  • Nobuyuki Imaishi, Hitoshi Nakamura, Hisashi Shono, Hajime Ino, Mitsuno ...
    1982 Volume 8 Issue 2 Pages 136-143
    Published: March 10, 1982
    Released: November 12, 2009
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    An experimental study was undertaken to clarify the surface-hydrodynamical acceleration phenomena prevailing along a horizontal gas/liquid interface of surfactant solutions upstream of a weir. Aqueous solutions of four surfactants (sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, n-hexanoic acid and n-heptanoic acid) were used for testing. A laser doppler velocimeter and the Wilhelmy method were used to measure distributions of velocity and surface tension respectively.
    Experimental results showed that the increase in surface velocity along the flow direction (surface acceleration) took place in concert with increase in surface tension near the weir.
    A simple model was proposed to elucidate the fundamental mechanism of surface acceleration. The model correlates the observed distributions of surface tension as well as velocity, except for the results observed in rather concentrated solutions of SDS and SDBS. It was revealed that adsorption rate process took an important role in developing the acceleration phenomena. This result suggests a new principle in measurement of adsorption rate constant.
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  • Haruhiko Ohya, Eiichi Kazama, Yoichi Negishi
    1982 Volume 8 Issue 2 Pages 144-149
    Published: March 10, 1982
    Released: November 12, 2009
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    An analysis has been made of the data of reverse osmosis concentration of aqueous ethyl alcohol solutions using the composite membrane PEC-1000 made by Toray Industries. Consistent membrane constants could not be obtained with osmotic pressure calculated from the freezing point depression of aquous ethyl alcohol solutions.
    On the contrary, consistent values are obtained with osmotic pressure from activities of water at room temperature. Reflection coefficient of PEC membrane a is estimated as 1.0 for reverse osmosis concentration of aqueous ethyl alcohol solutions. Hydraulic permeability constant Lp strongly depends on the ethyl alcohol concentration on the high-pressure side of membrane. The transport equations are expressed as follows :
    Jv=1.0×10-1exp (-αΔ-0.279π (c2)) (Δp-Δπ) (12)
    Js=1.288×10-4Δπ (9)
    (c2-c3) / (c1-c3) =exp (Jv/ck) (5)
    Calculated solution permeation flux Jv, and separation R, using Eqs. (5), (9) and (12) coincide well with measured data.
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  • Satoshi Yumoto, Haruhiko Ohya
    1982 Volume 8 Issue 2 Pages 150-154
    Published: March 10, 1982
    Released: November 12, 2009
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    Dialysis experiments were carried out to determine an over-all mass transfer coefficient U0 for dialysis. Six electrolytes and three kinds of polyethylene glycols of different molecular weight were used for dialysis material. The dialyzer consists of capillary membranes.
    It was found that U0 of electrolytes can be estimated from a diffusion coefficient and U0 of polyethylene glycols can be obtained from a molecular weight.
    The method of velocity variation was employed to determine the relationship between mass transfer coefficient and outside flow rate qOUT, or inside rate qIN of membrane.
    For the mass transfer coefficient in a outside diffusion film kf and qOUT, the relation (1/kf) ∝ (1/qOUT) 0.3 is obtained by means of a Wilson plot of 1/U0 vs. 1/qOUT. For U0 and qIN, experimental data showed that U0 decreased with increase of qIN in the range above 7 ml/min.
    This phenomenon can't be explained by a relation between a flow rate and a diffusion film thickness. This suggests that osmotic flow of water may increase with qIN.
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  • Katsuhide Murata
    1982 Volume 8 Issue 2 Pages 155-161
    Published: March 10, 1982
    Released: November 12, 2009
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    Previous kinetic studies on depolymerization have dealt mostly with the reaction in batchwise experiments. The present paper deals with the kinetics of thermal degradation of polymers taking place in the CSTR. For several cases of depolymerization, the expressions of chain length distribution, number average chain length and mean residence time were derived for the steady state of reactor content in the CSTR.
    For a monodispersed polymer that is thermally decomposed to volatiles with random depolymerization, the resultant expressions are as follows.
    Average chain length : DPn=2L+1-L (L+1) /DP0
    Average residence time : t=1/kir× [(2L+1) /L (L+1) -1/DP0]
    Chain length distribution : wDP=1/DP2-1/ [(2L+1) /L (L+1) -1/DP0]
    Fairly good agreement was found between the predicted distribution curve and the observed one for the reactor content of polyethylene, although agreement was poor for the volatilized product. These results suggest that the thermal degradation of polyethylene is a simultaneous reaction consisting of unzipping from the chain ends by which the volatilized products are produced and random scission which causes a decrease in molecular weight of reactor content.
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  • Katsuyuki Nakano, Koichiro Kusunoki
    1982 Volume 8 Issue 2 Pages 162-167
    Published: March 10, 1982
    Released: November 12, 2009
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    To clarify the adsorption amounts and adsorption sites of organic species during benzene hydrogenation, adsorption measurements of benzene and cyclohexane on Pd-Al2O3 catalysts were made at 108-175°C by using an electrobalance. It was found that reversible adsorption on the alumina support is predominant and the amount of adsorption on palladium atoms is negligibly small under a hydrogen atmosphere where hydrogenaton of benzene proceeds. On the other hand, there exist reversible adsorption on palladium atoms and irreversible adsorption in addition to reversible adsorption on the support under a hydrogen-free condition. Comparing these facts with the reaction rate data, the hydrogenation of benzene seems to occur between hydrogen adsorbed on the metal atoms and benzene adsorbed reversibly on the alumina support situated near the metal-support boundary.
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  • Shigeaki Kasaoka, Yusaku Sakata, Tetsuji Namoto
    1982 Volume 8 Issue 2 Pages 168-173
    Published: March 10, 1982
    Released: November 12, 2009
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    To develop a one-step direct reduction process in which CH4-reforming and iron ore reduction occur simultaneously, experiments on reduction of a hematite ore and three kinds of simulated iron oxides (pure αFe2O3, Al2O3 (5%) -αFe2O3, and SiO2 (5%) -αFe2O3) prepared by the precipitation method were carried out with CH4 (10080%) -CO2 (05%) -N2 mixture, mainly at 950°C. The rate and behavior of reduction from Fe2O3 to Fe were investigated with data obtained from simultaneous measurements of weight changes by a thermobalance and outlet gas composition by a high-speed gas chromatograph.
    Both the Al2O3 contained in ore/iron oxide and the CO2 (0.4 5%) mixed with CH4 showed remarkable effect in enhancing the rate of carbon deposit from CH4-cracking and CH4-CO2 reaction accompanying the formation of Fe through the reduction step from wilstite (FeO1-y, ) to Fe. However, the promising possibility that fractional reduction above 95% for iron are containing Al2O3 could be obtained by suppressing the carbon deposit was confirmed by reforming CH4 with coexisting CO2 (CH4+CO2→2CO+2H2) and allowing a longer contact time.
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  • Shigeaki Kasaoka, Yusaku Sakata, Shigeru Kayano, Yasuo Masuoka
    1982 Volume 8 Issue 2 Pages 174-180
    Published: March 10, 1982
    Released: November 12, 2009
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    Fundamental study of gasification of 19 kinds of coal chars was carried out gravimetrically with steam (H2O (24%) -N2) at 850°C and oxygen (O2 (10%) -N2) at 900°C. The fuel ratio of original coal ranged from 1.2 (brown coal) to 7.9 (anthracite), and each sample char was prepared under the same conditions. The main results obtained were as follows :
    1) The fractional gasification f, vs. gasification time θ, curves could be fitted very closely with the equation, f=-1-exp (-aθ>b); (a, b =constant), independent of coalification rank, gasifying conditions and sigmoidal character of f vs. θ curves. This rate equation was derived by assuming that a rate constant k was dependent on the extent of gasification as k (f) = a1/bb (-ln (1-f)) (b-1) /b.
    2) An average rate constant, k =∫10 k (f) df, which was nearly equal to k at f=0.5, and θ to be f=0.5 (θf=0.5) were found to be useful for evaluation of gasification reactivity of char, and to be correlated with fuel ratio of coal and atomic ratio of H/C of coal and/or char with fairly good approximation.
    3) By normalizing gasification time θ with θf=0.5 to be τ, rate-curves (f vs. θ) of steam or oxygen gasification over 19 kinds of chars were correlated to a characteristic curve shown as f = 1-exp (-AτB); (A, B= constant) respectively.
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  • Kenichi Ushiki, Hideo Kato, Chihiro Fukumoto, Koichi Iinoya
    1982 Volume 8 Issue 2 Pages 181-187
    Published: March 10, 1982
    Released: November 12, 2009
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    This paper describes the collection mechanism, partial collection efficiencies and re-entrainment performance of a three-segment separator, which is a typical ascending-droplet type used in industry. Using a two-dimensional model bend which closely resembles the geometry of the three-segment type, and supposing that the radial droplet concentration is uniform due to turbulent mixing, the theoretical collection efficiencies are calculated when the particle's Reynolds numbers are more than unity. The estimated results agree well with the experimental values. The collection efficiencies become lower as gas velocity becomes higher in the usual velocity range because of the deviation of particle drag from Stokes' law, when the inertial parameter remains constant.
    Grooves on the segments for preventing reentrainment increase the pressure loss to as high as 1.7 times, though they do not affect the partial collection efficiencies. Moreover, they decrease the lower limit of re-entrainment gas velocity, though they do not remarkably reduce the collection efficiencies when the gas velocity becomes too high.
    From the facts described above, we may conclude that grooves are not recommended. The re-entrainment gas velocity becomes much lower when water-repelling blades are used, since the collected water droplets are gathered into large semi-spherical droplets protruding from the blade. However, the water-absorbing surfaces also decrease the re-entrainment velocity, since the film of collected water on the blade is too thick. The vertical lower edges of the blades significantly prevent re-entrainment.
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  • Eiji O'Shima, Masato Tanaka
    1982 Volume 8 Issue 2 Pages 188-193
    Published: March 10, 1982
    Released: November 12, 2009
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    An experimental investigation was performed to investigate the effect of various solid powders on stability of particles in the suspension polymerization of styrene.
    It was found that the stability of the suspension is largely dependent on the contact angle of the solid powders with the dispersed phase. Among the solid powders added, the ones with contact angle above ca. 50°, i.e. nickel oxide, calcium carbonate, cobalt oxide, aluminum oxide, aluminum hydroxide and zinc sulfide, were found to be effective as suspension stabilizers. The solid powders with contact angle below 50°, i.e. kaolin and carbon black, behave as the emulsion breaker.
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  • Yoshiro Kitamura, Teruo Takahashi
    1982 Volume 8 Issue 2 Pages 194-198
    Published: March 10, 1982
    Released: November 12, 2009
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    Wind tunnel experiments were performed to investigate the drift of oil slicks on a water surface induced by wind. The moving rates of leading edge were measured for kerosene and n-heptane slick transported by wind of velocities of 0.3 2.18 m·s-1. When the oil slick spread on a water surface is blown by the wind, its leading edge proceeds due to the spread itself and the drift current induced by wind. The drift current was obtained by subtraction of the spreading rates from the experimental moving rates of leading edge.
    The drift current data for two kinds of oils agree with those for the oil-free water surface. The ratio of the drift current of slicks to the wind velocity approaches asymtotically the constant value 0.033 as the Reynolds number based on water depth, drift current and kinematic viscosity of water increases.
    Based on the experimental results, an estimation is developed as to how far an actual spill extends when the wind blows on the sea. The estimated values are compared with the field data obtained during actual accidents. The large difference between the field data and calculation based on the spreading on a calm water surface can be well explained by drift due to the wind.
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  • Shimio Sato, Takao Hashimoto, Minoru Morita
    1982 Volume 8 Issue 2 Pages 199-204
    Published: March 10, 1982
    Released: November 12, 2009
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    Dependence of the decomposition rate of a coal in direct liquefaction on coal rank was studied.
    The following results were obtained for coals of carbon content from about 70% to 85% Characteristics of the decomposition could be explained well from the scheme in which the original coal is constituted of two components having different reactivities. The contents of the less-reactive component and the remainder, i.e. the more-reactive one, in the original coal were considered approximately equal to the amount of fixed carbon and volatile matter, respectively. The decomposition rate of the former increased with a rise in coal rank; that is, the increase of carbon content or the decrease of amount of residual oxygen, except for the oxygen detected as functional groups like-COOH, in the original coal. The decomposition rate of the latter decreased with a rise in coal rank; that is, the increase of carbon content or the total amount of residual oxygen and carbonyl group in the original coal. The above conclusions suggest that the decomposition rate of a given coal can be estimated from elemental data, by such methods as ultimate analysis of the original coal.
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  • Shimio Sato, Takao Hashimoto, Minoru Morita
    1982 Volume 8 Issue 2 Pages 205-210
    Published: March 10, 1982
    Released: November 12, 2009
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    Dependence of a coal's decomposition rate in direct liquefaction on coal rank and liquefaction temperature were studied over a wider range of experimental conditons than in the previous paper.
    The results were as follows : (1) Decomposition rate constants depended on coal rank indices in a rather complex manner over a wide range of rank indices, while they depended on the indices in a monotonous manner similar that in the previous paper for limited index values, corresponding to those previously investigated, within the range of index values. When carbon content, for example, was used as a typical rank index and the decomposition rate constants of various coals were plotted against their index values, those of the less reactive component showed a maximum at about 85 wt % carbon content and a minimum at about 70 wt % carbon content, and those of the more reactive one showed a decrease, accompanying marked changes at the above carbon contents, with increasing carbon content. (2) According to dependence of the rate constants on the liquefaction temperature and correspondence between the components and fixed carbon, and volatile matter, the coals were considered to have liquefied through the following scheme under the liquefaction conditions in this report.
    coal1 (fixed carbon) → preasphaltene → asphaltene

    coal2 (volatile matter) → further products
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  • Hitoshi Takase, Hajime Unno, Takashi Akehata, Yasuo Kato, Hisashi Kish ...
    1982 Volume 8 Issue 2 Pages 211-216
    Published: March 10, 1982
    Released: November 12, 2009
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  • 1982 Volume 8 Issue 2 Pages 217a
    Published: 1982
    Released: February 19, 2010
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  • 1982 Volume 8 Issue 2 Pages 217b
    Published: 1982
    Released: February 19, 2010
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  • 1982 Volume 8 Issue 2 Pages 217c
    Published: 1982
    Released: February 19, 2010
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  • 1982 Volume 8 Issue 2 Pages 217d
    Published: 1982
    Released: February 19, 2010
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  • 1982 Volume 8 Issue 2 Pages 217e
    Published: 1982
    Released: February 19, 2010
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  • 1982 Volume 8 Issue 2 Pages 217f
    Published: 1982
    Released: February 19, 2010
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  • 1982 Volume 8 Issue 2 Pages 217g
    Published: 1982
    Released: February 19, 2010
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