KAGAKU KOGAKU RONBUNSHU
Online ISSN : 1349-9203
Print ISSN : 0386-216X
ISSN-L : 0386-216X
Volume 7 , Issue 6
Showing 1-17 articles out of 17 articles from the selected issue
  • Kyoichi Saito, Terukatsu Miyauchi
    1981 Volume 7 Issue 6 Pages 545-548
    Published: November 10, 1981
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Diffusivities of uranium in artificial seawater were measured in the range of uranium concentration 10-1, 000 μg-U/l at temperatures of 535°C. The following experimental equation is presented :
    D=0.0475exp (-23, 500/RT)
    where D is diffusivity [cm2/s], R is gas constant [J/mol ·K], T is temperature [K].
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  • Koichi Murata, Kunihiro Nakashima, Kazumori Funatsu, Hisashi Shinohara
    1981 Volume 7 Issue 6 Pages 549-555
    Published: November 10, 1981
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Viscosity and normal stress difference of polymer blends such as polyethylene (PE) -polypropylene (PP) and polyethylene (PE) -polystyrene (PS) systems were measured and the morphology of extruded samples was observed with the electron microscope.
    Fraction dependency of viscosity was the same as shown by the result of the previous work. In the measurement of normal stress differences with the flow birefringence method, only the first normal stress difference was obtained and it was found that normal stress differences of these blends were smaller than those of the pure components over most fractions.
    Power law was used to study shear rate dependencies of viscosity and normal stress difference. A great change in the power law exponents of these flow characteristics occurred at a PE fraction of 0.6. It was concluded that the flow mechanism changes near that fraction. The stress-optical coefficient necessary for the flow birefringence method was experimentally measured and its tendency was found to be the same as those predicted by the theory of rubber elasticity. The morphology observed with electron micrograph suggested some information on microscopic flow behavior.
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  • Mompei Shirato, Toshiro Murase, Masashi Iwata
    1981 Volume 7 Issue 6 Pages 556-563
    Published: November 10, 1981
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    To obtain a simplified method for analysing the pressure distribution of power law fluids in screw extruders, the conventional flow equation based on the flat-plates representation of the screw channel is modified in definition of an average differential viscosity. Simplified equations for predicting the pressure variations in the extruders of both constant pitch-straight taper type and constant channel depth-varying pitch type are derived, in consideration of the patterns of drag, pressure, leakage and transverse flows within the channel cross section. A correction factor for better approximation of the average differential viscosity is evaluated by calculating the rates of pressure flow from Hattori's flow equations. The empirical equations of shape factors for the flat-plates model are also presented by computing the rates of axi-symmetrical flows from the non-Newtonian equations of motion. It is shown that the pressure profiles along the axis of the screw channel and the screw characteristics can be easily estimated in ways similar to those for extrusions of Newtonian fluids.
    Experimental data obtained by the screw extrusion of power law fluids with flow be havior index n of 0.2010.876 were in fairly good agreement with the predictions.
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  • Chiaki Kuroda, Kohei Ogawa, Ichiro Inoue
    1981 Volume 7 Issue 6 Pages 564-567
    Published: November 10, 1981
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    A method for simultaneous measurement of static pressure fluctuations and velocity fluctuations in turbulent liquid flow is proposed on the basis of the electrochemical technique for measurement three-dimensional velocity fluctuations by use of a spherical multi-electrodes probe, which senses pressure fluctuations by an electric pressure transducer. This method is usable in the turbulent field where the fluctuating flow angle θ between the probe axis and the velocity vector is 0°<θ<30° and Reynolds number Re based on the diameter of the probe is about 103<Re <104. It was experimentally confirmed that the response of the probe is improved in proportion to the main flow velocity U, for example, about 50 Hz in the turbulent flow field of U_??_0.5 m/s.
    By using this prove, the zone downstream from a grid in a circular open channel is investigated and some new experimental results, such as linear relations between the root-mean-square value of static pressure fluctuarions and the representative turbulent kinetic energy, are obtained.
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  • Kenkichi Izumi, Akira Yamada, Toshio Sawa, Sankichi Takahashi
    1981 Volume 7 Issue 6 Pages 568-574
    Published: November 10, 1981
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Scale prevention by the pH control method in a multi-stage flash evaporator for desalination of sea water was examined by using a 10-stage flash evaporator with a capacity of 100 m3 per day.
    Tests on the pH control method were carried out at four different injection rates of sulfuric acid into feed sea water. The tests showed that formation of alkaline scale was prevented when the injection rate of sulfuric acid was 110 ppm for feed sea water. Sulfate scale did not precipitate when the maximum temperature of the brine was 120°C, and the concentration factor of the brine was 2.0.
    A program for calculation of the mass balance of scale substances was developed with consideration of the reaction rate of carbonate ion in the brine. By comparison between experimental data and calculated values, the supersaturation characteristics of calcium carbonate in brine were determined.
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  • Masao Kobari, Yukio Shimizu, Mihoko Endo, Hikoji Inazumi
    1981 Volume 7 Issue 6 Pages 575-580
    Published: November 10, 1981
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    To clarify the mechanism of drying and to develop a method of estimating the drying rate of fibrous sheet, the effective thermal conductivities of wet fibrous sheet were measured by the hot wire method at various moisture contents, void fractions and temperatures. Based on the assumption that the thermal conductivity of wet fibers could be expressed by the volumetric average of water and fibers, a heat conduction model was developed for porous structure of wet fibers. It is shown that the values of effective thermal conductivity calculated from a formula obtained by the above model agree well with the experimental data.
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  • Noriaki Kubota, Teiriki Tadaki
    1981 Volume 7 Issue 6 Pages 581-587
    Published: November 10, 1981
    Released: February 19, 2010
    JOURNALS FREE ACCESS
    Waiting time distributions (WTD) are measured over several weeks. A continuous distribution model is presented in which nucleation is assumed to be induced heterogeneously by active sites distributed among sample solutions. In the model, an activity distribution of the sites is expressed by a continuous function (gamma distribution). By anlysing the measured WTD with the model, the following results are obtained. (1) The measured WTD is well expressed by the model. (2) The WTD is determined by a few relatively more active sites and is not affected by less active sites, which are probably contained in the sample in great number. (3) Over a longer period of WTD observation, nucleation by less active sites occurs. That is, the sites of less activity can be detected by longer observation. The relation between minimum activity detectable k0c [s-1] and duration of observation θm [s] is given by the equation k0cθm≅10-1.
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  • Shinichi Hibino, Hideki Tsuge
    1981 Volume 7 Issue 6 Pages 588-594
    Published: November 10, 1981
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Longitudinal concentration distributions were measured under various conditions in the case of CO2 absorption by water in single and multistage bubble columns. By measuring the variance of external age distribution function in the multistage column and by using the relationships between gas holdup, dispersion coefficient and volumetric mass transfer coefficient, and the mean superficial gas velocity in single-stage bubble column, the concentration distributions in the multistage column could be estimated by D-B model, in which it was assumed that the dispersion model was applicable in each stage and that there was back flow between stages.
    The concentration distributions were expressed more adequately by the D-B model than by the back flow model with increase of the ratio of stage distance to column diameter. It was found that the differences in outlet concentrations calculated by the two models were about 2%.
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  • Hikoji Inazumi, Junjiro Kawasaki, Takanori Suzuki, Chikara Maruyama
    1981 Volume 7 Issue 6 Pages 595-601
    Published: November 10, 1981
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Some numerical solutions were obtained for the basic nonlinear partial differential equations based on the penetration model for nonisothermal gas absorption accompanied by (1, 1) th-order chemical reaction into laminar falling liquid film without ripples, derived by considering sensible heat transfer between gas and liquid, vaporization of solvent, the release of heat due to solution and reaction and the change of ionic strength.
    Experiments were carried out using wetted-wall columns (column height =5 200 cm) for the absorption of CO2 into NaOH aq. sol. containing a small amount of surface active agent (0.05 vol %).
    It was confirmed that the experimental values of absorption rate agreed with the numerical solutions obtained in this work.
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  • Atsushi Inaba, Hakuai Inoue
    1981 Volume 7 Issue 6 Pages 602-609
    Published: November 10, 1981
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Polystyrene was degraded at 340-380°C and the change of molecular weight under degradation was investigated. The results showed that the change of weight-average molecular weight during reaction depends on the conversion and the operating conditions (gas-phase pressure and agitating speed). This effect of operating conditions appeared not to be explained by the weak links theory, nor by the chain transfer reactions of the polymer radicals alone.
    The production rates of styrene monomer as well as the change of average molecular weight under the operating conditions could be simulated by computer calculation based on a model with the mass transfer rates of the products, the equalibrium concentrations of the products and the radical polymerization mechanism.
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  • Norio Arai, Masanobu Hasatani, Sachio Sugiyama
    1981 Volume 7 Issue 6 Pages 610-614
    Published: November 10, 1981
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The combustion rate of a char particle produced by the pyrolysis of surplus activated sludge was measured in N2-O2 atmosphere by using a micro thermo-gravimetric analyzer (TGA). The effect of combustion temperatures, ambient oxygen concentrations, pyrolysis temperatures and particle-diameters of a char on the combustiom rate was studied.
    As a result, the following conclusions were drawn for the range of the present experimental conditions :
    1) At combustion temperatures below 550°C, the overall combustion rate is controlled by the rate of chemical reaction and is proportional to the first order of the oxygen concentration and the carbon concentration in the solid particle, simultaneously.
    2) The combustion rate constants are considerably affected by the oxygen content within a char particle produced. It is observed that both the energy of activation and the frequency factor of reaction decrease with increase in oxygen content.
    (3) It is suggested from a comparison of the present results with the existing kinetics data for coal chars that the combustibility of a char particle produced from a coarse solid fuel may depend on oxygen content. Thus, conclusion (2) is applicable to the extent of coal chars.
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  • Masanobu Hasatani, Norio Arai, Yasuhiko Suzuki, Sachio Sugiyama
    1981 Volume 7 Issue 6 Pages 615-620
    Published: November 10, 1981
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Continuous combustion of chars produced by the pyrolysis of surplus activated sludge was carried out in a laboratory-scale moving bed reactor capable of both parallel-and counter-flow. By comparing the experimental results obtained in both kinds of solid-gas contacting operations, the following conclusions were drawn :
    1) Combustion conditoins being equal, combustion temperature in counter-flow is higher than that in parallel-flow. Total combustion efficieney, however, is rather lower in counter-flow than in parallel-flow.
    2) In counter-flow, the exhaust gas contains about 10 vol% CO and carries a strong, rank odor which is not detectable in parallel-flow.
    3) The fractional convension of fuel-N in chars into fuel NOx decreases with decreasing air-fuel stoichiometric ratio. The fractional conversion in parallel-flow is much lower than that in counter-flow.
    4) Ash component within surplus activated sludge can be used effectively as a chemical absorbent of NO.
    5) It is suggested from conclusions (1) to (4) that two-stage combustion method in which parallel- (combustion) and counter-part (pyrolysis and gasification) are combined organically would be effectual for the gasified-combustion of a coarse solid fuel.
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  • Tamotsu Hanzawa, Kunio Kato, Teiriki Tadaki
    1981 Volume 7 Issue 6 Pages 621-627
    Published: November 10, 1981
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The epitaxial deposition rate on a susceptor surface in a horizontal reactor is numerically calculated from fundamental equations for transport phenomena in the reaction chamber. The calculated deposition rates are compared with the experimental growth rate of silicon reported in the previous paper and the calculated values agree well with the experimental values.
    The effect of the operating conditions upon the calculated deposition rate is also investigated in the case where the overall reaction rates are mass transfer rate control and surface reaction rate control. In mass transfer rate control, the deposition rate increases when the feed rate of gas or the concentration of feed gas increase, and become more uniform when the feed rate of gas increases or Gr decreases. The deposition rate in the case of surface reaction rate control become generally more uniform than those in the case of mass transfer rate control under the same operating conditions.
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  • Akira Suzuki, Keishi Gotoh
    1981 Volume 7 Issue 6 Pages 628-634
    Published: November 10, 1981
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    A computer-simulated experiment is carried out for the fracture of a randomly packed bed of equal spheres due to its own weight. An empirical equation of the tensile strength of the particle beds is obtained from computer experiments and is found to be in good accordance with the data of Cheng for actual powder beds of aluminum oxide. A detailed comparison is made between the present result and the well-known Rumpf's expression.
    It is also noted that tensile strength no longer exists in a unifomly random packing of equal spheres where average packing fraction is less than 0.235. In other words, the particle bed cannot be the continum in this region.
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  • Atsushi Shimizu, Hakuai Inoue
    1981 Volume 7 Issue 6 Pages 635-642
    Published: November 10, 1981
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The reaction rate of hydrolysis of starch by the immobilized glucoamylase-collagen membrane was investigated. The optimum pH for the immobilized enzyme was at a lower value, pH 4.5, whereas that for the free enzymes was pH 5.0. The intrinsic reaction rate for the immobilized enzyme was proportional to the starch concentration, while that for the free enzyme could be expressed by the Michaelis-Menten equation.
    The effective diffusion coefficient of starch in the collagen membrane was also measured by the quasi-steady state method. It was shown that the effective diffusion coefficient depended on the amount of bound enzyme.
    The effectiveness factor of the immobilized enzyme calculated from the experimental results was in good agreement with the theoretical value calculated on the assumption that the intrinsic reaction rate for the immobilized enzyme was proportional to the starch concentration.
    Performance of the membrane reactor, pressure drop and effect of the flow rate on the overall reaction rate were studied.
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  • Yukio Yanagisawa, Hajime Nishimura
    1981 Volume 7 Issue 6 Pages 643-650
    Published: November 10, 1981
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    A new method for the measurement of nitric oxide was developed from the principle of chemical reaction engineering. The principle of the measurement is the oxidation of NO to NO2 followed by the absorption of NO2 to alkaline solution. Coexisting NO2 in ambient air is absorbed simultaneously. NO concentration is calculated from the amount of absorbed NO2 and NO2 concentration measured by another method. The feature of the method is to use filters as carriers of both oxidizing and absorbing agents. The layer of filters also serves to control the rate of diffusion of gas. The device, 50 ×38 mm in size, weights only 15 g. It could measure NO concentration in ambient air with the accuracy of 50% by exposure of several hours.
    In the first part of the paper, a theoretical analysis is made on the possibility and performance of such a device and the optimum design is proposed. In the second part, the selection of appropriate oxidizing agent and the determination of the optimum thickness of oxidizing layer are discussed based on experimental results. Finally, the results of performance testing of the device are presented.
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  • Masanobu Hasatani, Norio Arai, Sachio Sugiyama
    1981 Volume 7 Issue 6 Pages 651-653
    Published: November 10, 1981
    Released: November 12, 2009
    JOURNALS FREE ACCESS
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