KAGAKU KOGAKU RONBUNSHU
Online ISSN : 1349-9203
Print ISSN : 0386-216X
ISSN-L : 0386-216X
Volume 5 , Issue 6
Showing 1-17 articles out of 17 articles from the selected issue
  • Masao Kobari, Yukio Shimizu, Mihoko Endo, Hikoji Inazumi
    1979 Volume 5 Issue 6 Pages 547-552
    Published: November 10, 1979
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    The equilibrium moisture content of treated tobacco (extracted with hot water) and pulp, both of which consist of cell wall materials, has been measured at temperatures ranging from 20 to 80°C and relative humidities from 0 to 97%. As such materials are most likely to be denatured under high humidity, a new experimental method is presented here to permit rapid determination of equilibrium moisture content. The equilibrium moisture content of treated tobacco determined so far by this method could be expressed as a function of adsorption potential.
    The relation between equilibrium moisture content and capillary suction potential in wet treated tobacco was studied theoretically and experimentally, and it was confirmed that the adsorption of water on the material under high humidity is controlled by the capillary condensation phenomenon.
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  • Kazumori Funatsu, Shinichi Shoda, Hisashi Shinohara
    1979 Volume 5 Issue 6 Pages 553-558
    Published: November 10, 1979
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    Onset of unstable flow of polymer melts, which is sometimes called melt fracture, was studied in relation to nozzle structure. Nozzle structure was changed in length, entrance angle and diameter of curvature at entrance. Two kinds of polyethylene samples and one polypropylene sample were used.
    The flow curves of polyethylene were discontinuous, but that of polypropylene was continuous. Three types of unstable flow, namely surface fracture, slip fracture and inner fracture, were observed. The two polyethylene samples and the polypropylene sample showed slip fracture alone, both surface and slip fracture, and both surface and inner fracture, respectively.
    Though the discontinuity of polyethylene did not disappear, tapered nozzles made the extrudate deformation by slip fracture very much smaller, and curved nozzles like a quadrant nozzle almost suppressed the deformation by slip and inner fracture. On the contrary, surface fracture occurred at lower shear rate through curved nozzles.
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  • Kazumori Funatsu, Shinichi Shoda, Hisashi Shinohara
    1979 Volume 5 Issue 6 Pages 559-564
    Published: November 10, 1979
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    Two kinds of polyethylene, which have a discontinuous point on their flow curves, and one kind of polypropylene, which has no discontinuous point, were used.
    From the isochromatic patterns measured by the flow birefringence method, strong stress concentration developing near the edge of entrance in nozzles with an entrance angle of 180° were observed to decrease considerably through tapered nozzles or curved nozzles, and in some cases slip fracture and inner fracture were almost suppressed.
    The variation of temperature rise was correspondent with onset of surface fracture, slip fracture and inner fracture.
    Slip fracture caused much more temperature rise than did surface and inner fracture.
    The yield stress of the cooled extrudates did not change over the shear rate for the various nozzles.
    Measurement of molecular orientation by X-ray diffraction and polarized fluorescent light intensity showed clearly the difference in micro-structure between smooth and deformed extrudates.
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  • Teruo Takahashi, Toshiro Miyahara, Yasuyoshi Sanada
    1979 Volume 5 Issue 6 Pages 565-570
    Published: November 10, 1979
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    The paper presents the results of a study of drop formation due to the collapse of a single bubble at a gas-liquid interface in the Morton number range 2.52×10-119.3×10-8 and at bubble diameter 0.060.5 cm. A bubble collapsing at the interface produces some droplets at the bubble diameter smaller than the specific one and maximum height of rise of drop at the bubble diameter of about 2 mm.
    By means of dimensional analysis, correlations of diameter and projection velocity of the first drop are obtained in terms of the bubble diameter, the Morton and Ohnezorge number, and the Reynolds, Morton and Bond number, respectively. From consideration of the results, the critical point for drop formation is clarified. Furthermore, a simple model for drop formation reveals the contribution fraction of the surface energy released by the collapse cf a bubble to the kinetic energy of produced drops.
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  • Ryuzo Ito, Yushi Hirata, Yungdae Ma, Fumiaki Yoshida
    1979 Volume 5 Issue 6 Pages 571-577
    Published: November 10, 1979
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    The velocity of liquid surface impinged by an air jet has been investigated experimentally and analytically. The surface velocity in the impinging region was measured by use of the hydrogen bubble method. In the analysis, a laminar boundary layer approximation has been used. Because of the large difference in density between liquid and air, it was assumed that air flows over a flat solid plate instead of on the liquid surface and that liquid is pulled into movement by the shear stress of gas phase acting on the solid surface. The values of surface velocity calculated by using these assumption and the measured pressure distribution on the liquid surface were in good agreement with the measured values. It was also found that the surfactant contained in the air jet plays an important role in the behavior of the liquid surface.
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  • Kiyotaka Sakai, Yoshio Muramatsu, Hiroshi Nakamura, Heng-Sheng Lee
    1979 Volume 5 Issue 6 Pages 578-583
    Published: November 10, 1979
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    Submerged combustion equipment has a very high thermal efficiency, but the pressure drop is unfortunately very high within the equipment. A heat exchanger with direct contact of combustion gas and liquid using packed column has been developed in an attempt to realize a substantial improvement. It was found possible to maintain a high thermal efficiency even if the pressure drop is very low. Vaporization is likely to occur at the higher liquid temperature, so that with this new equipment operation at lower liquid temperature is effective. It became possible to use a town gas as fuel because of the low pressure drop. It was also found that the heat and mass transfer model for the packed column using the empirical equations of humidity was successful in explaining the phenomena in the high-temperature flue gas. The thermal efficiency difference between counter-current and parallel-flow operation was small within the low liquid temperature range.
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  • Kenji Takahashi, Masanobu Maeda, Shigeru Ikai
    1979 Volume 5 Issue 6 Pages 584-590
    Published: November 10, 1979
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    Laminar heat transfer from a flat plate set parallel to flow direction of a power-law non-Newtonian fluid was studied experimentally. Aqueous carboxymethylcellulose (CMC) solution of 0.251.25% in weight concentration was adopted as a power-law fluid. The surface of the plate was plated with nickel and was electrically heated to uniform temperature.
    The velocity distribution in the boundary layer on the flat plate for CMC solution measured by a laser Doppler velocimeter agrees sufficiently with the values obtained theoretically by Acrivos et al. The obtained heat transfer coefficients as a function of generalized Reynolds number and generalized Prandtl number coincide with the theoretical values given by Acrivos et al.
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  • Tatsuki Matsuo, Nobuo Ishizaki, Hideki Komagata
    1979 Volume 5 Issue 6 Pages 591-595
    Published: November 10, 1979
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    To elucidate the mechanism of mass and momentum transfer in a corrugated board of activated carbon fiber paper, experiments on pressure drop characteristics and breakthrough curve for adsorption were carried out.
    It is found that pressure drop increases linearly with increase in superficial line velocity u and that thickness of mass transfer zone Za increases linearly with increase in u and varies inversely with the surface area of the tube wall.
    These results suggest that the rate-determining process of adsorption of corrugated board is the mass transfer from the bulk fluid to the tube wall.
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  • Ken Toyokura, Makoto Uchiyama, Izumi Hirasawa, Masaki Kawai
    1979 Volume 5 Issue 6 Pages 596-600
    Published: November 10, 1979
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    Effect of collision by agitation of impeller on secondary nucleation rate of K-Alum was studied in the range of nucleation rate increasing with impeller rotational speed. Fluidized bed of seed crystal with a paddle-type impeller was used as the crystallizer, and the height of seed bed was adjusted to be the same as the width of the impeller to allow for seed crystals to be directly agitated by the impeller. The total number of secondary nuclei generated was observed by direct counting under a microscope.
    Secondary nucleation rates are correlated with supersaturation, and these powers of supersaturation are in the range 1.3-1.6, depending upon impeller rotational speed and impeller diameter. These values of 1.3-1.6 are smaller than the power of 3.3 obtained by fluidized seeds and by seeds of the minimum size to be able to produce secondary nuclei, and are almost identical with that for crystal growth rate. This result is discussed in terms of the damaged surface repairing model reported by Larson et al.
    New equation of secondary nucleation rate by impeller agitation is derived by improving the semi-theoterical model of secondary nucleation rate in a stirred tank reported by de Jong et al., and experimental data obtained in this study are correlated by that equation.
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  • Shinichiro Nomura, Tatsuo Tanaka
    1979 Volume 5 Issue 6 Pages 601-608
    Published: November 10, 1979
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    Using a model of particles uniformly dispersed, the rate of pressure rise due to dust explosion in a spherical vessel is theoretically studied. Bartknecht reported an experimental relationship called the “cubical law” between maximum rate of pressure rise and volume of vessel, that is, dp/dt|max·V01/3=KG. A similar relationship is theoretically derived in this paper, and it is shown that KG is a constant depending upon particle size and dust cloud concentration. Calculated results of the characteristics of starch dust are largely consistent with the past experimental data.
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  • Hakuai Inoue, Masaki Funakoshi
    1979 Volume 5 Issue 6 Pages 609-615
    Published: November 10, 1979
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    By a new catalyst preparation technique, nickel metal was deposited uniformly on the inner wall of an aluminum tube, and a high active nickel catalyst tube wall reactor was designed.
    The kinetics of methanation of carbon monoxide on this catalyst was measured and the rate was found to be correlated by the equation v=kpco1/2pH2/1+Kpco,
    A catalytic mechanism based on this rate equation is proposed.
    Methanation by this reactor was analyzed on the basis of the diffusion mechanism of the fluid, and the radial concentration profile and the conversion of carbon monoxide were calculated. The results show that the tube wall reactor is suitable for methanation not only by the rapid rate of removal of reaction heat, but also it is preferable because of the acceleration effect of the reactant concentration decrease produced by diffusion resistance on catalytic reaction rate.
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  • Michitaka Suzuki, Kazutaka Makino, Tadao Tamamura, Koichi Iinoya
    1979 Volume 5 Issue 6 Pages 616-622
    Published: November 10, 1979
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    To elucidate the mechanical behaviour of a particle system, it is necessary to express quantitatively the distribution of the neighbouring particles, i.e. the first-layer particles, and to analyse the action forces of these particles with respect to a specified particle. In this paper, the distributions of the first-layer particles are experimentally investigated in two-dimensional random-packing systems of monosize spheres or discs by use of a computer model and a settling method. From these results, it is shown that the probability density distributions of these particles can be approximately described by an analytical model based on the assumption of homogeneous and isotropic arrangement, if the first-layer particle is geometrically defined as one which can be fully looked at from the center of a specified particle.
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  • Ryuichi Aoki, Fumiyoshi Kamiya, Hiroshi Murata, Hiroshi Homma
    1979 Volume 5 Issue 6 Pages 623-629
    Published: November 10, 1979
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    Concerning plug-flow, which is an important form of pneumatic conveying of powders and granular materials, in order to establish a stable plug-flow condition a method of introducing light ball stoppers has been examined. Rape seeds and ping-pong balls were used as granular material and stoppers respectively. By applying a reciprocating motion to a feeding box placed at the inlet of the conveyor pipe, continuous plug-flow was obtained.
    The flow condition was determined by factors such as feeding rate, gas rate and the speed of vibration of the feeding box. The relations between plug velocity, plug length, frequency of plug formation and the aforementioned factors were experimentally obtained.
    A method to calculate the pressure difference across a plug and to estimate the plug velocity is presented. Using the calculated results, conveying efficiency was compared for each gas velocity.
    It is concluded that efficiency is highest under the condition where the gas speed is as low as the critical conveying velocity. This result is very favourable to prevent crushing or to minimize abrasion of the friable particles during the transportation processes.
    Also, the effectiveness of the stopper was clearly shown compared with the case where no stoppers were used.
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  • Mompei Shirato, Toshiro Murase, Hidetoshi Mori, Tadashi Ogura, Eiji Na ...
    1979 Volume 5 Issue 6 Pages 630-636
    Published: November 10, 1979
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    To obtain a more simplified method for analyzing the internal dehydration mechanism of granular beds in the gravitational field, the conventional equation for flow in capillaries is empirically modified in view of the existence of flow of a filmwise liquid. In the new equation, the effects on deliquoring rates due to movement of a filmwise liquid are represented in the term of change in the so-called equivalent drainage height hc in behalf of Nenniger-Storrow's film drainage concept. A simple equation for predicting the average saturation Sav vs. the time θ is derived. A mathematical method for calculation of the moisture distribution in beds at a given time is also presented, by visualizing the beds as an assemblage of capillary tubes of various radii determined from the final equilibrium moisture distribution in accord with the conventional method, and also in consideration of capillary flow accompanied by a filmwise flow in each tube. It is shown that the time changes in average moisture content and moisture distribution can be easily calculated.
    Experimental data for gravitational drainage of packed beds of glass beads, calcium carbonate particles and Soma standard sand compare very favourably with calculations under the conditions where the ratio of final drain height to bed height (hc·∞/H) ranges from 0.32 to 0.72.
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  • Masayoshi Sadakata, Michihiko Imagawa, Makoto Nawada, Takehiko Furusaw ...
    1979 Volume 5 Issue 6 Pages 637-643
    Published: November 10, 1979
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    In this study, a new combustion-heating system which can realize both pollution control and energy saving was proposed, developed and tested. The system consists of a combustion furnace and a new-type multifunctional heat exchanger. At the combustion furnace, emissions of thermal and fuel NOx are reduced by controlling the combustion air flow rate under the stoichiometric air ratio. Then, the combustion flue gas including CO, H2 and soot are sent to the new-type heat exchanger. This heat exchanger is a rotary continuous type which is designed for soot collection and catalytic combustion of CO and H2 as well as for preheating combustion air. Accordingly, flue gas leaves the heat exchanger as clean, room-temperature gas.
    A model plant of this system was constructed and tested under variable conditions. The main results were as follows. (i) The overall reduction rate of NOx was improved up to 90% in this system. (ii) Combustion of unburnt products could take place in the catalytic layer when the inlet gas temperature was above 170°C. (iii) The maximum collection efficiency of soot in the stainless fiber filter was 60%.
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  • Jun-ichi Koizumi, Isamu Yabe, Shuichi Aiba
    1979 Volume 5 Issue 6 Pages 644-649
    Published: November 10, 1979
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    The Monte Carlo Method was applied to solve for light absorption rate in a fermentor of photosynthetic bacterium, Rhodopseudomonas spheroides S, which was subjected to the incident light of a specific wavelength distribution.
    Calculation results agreed well with experimentation by chemical actinometry using Reinecke's salt solution. This agreement is considered to justify, in toto, the numerical calculus procedures and some assumptions employed.
    Calculation results clearly demonstrated that light absorption efficiency, which increased apparently with increase of cell concentration, leveled off at around 0.7 in this experimental setup.
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  • Ryuzo Ito, Yushi Hirata, Toru Fukada, Shigehisa Endo, Hitoshi Emi, Chi ...
    1979 Volume 5 Issue 6 Pages 650-655
    Published: November 10, 1979
    Released: October 21, 2009
    JOURNALS FREE ACCESS
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