KAGAKU KOGAKU RONBUNSHU
Online ISSN : 1349-9203
Print ISSN : 0386-216X
ISSN-L : 0386-216X
Volume 14 , Issue 5
Showing 1-26 articles out of 26 articles from the selected issue
  • Kunio Kato, Hideki Ishihara, Keizaburou Yoshie, Kenji Kakinuma, Takayu ...
    1988 Volume 14 Issue 5 Pages 575-582
    Published: September 10, 1988
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    In many electronic systems such as a telephone exchange, the circuit cards are vertically aligned. These circuit cards are usually cooled by natural convection.
    To analyze the heat transfer in electronic circuit cards, natural convection heat transfer between two vertical parallel plates was investigated. Two plates were symmetrically or asymmetrically heated. The average heat transfer coefficient from the plate was affected by Grashof number, plate spacing, height of plate, temperatures of the two plates and open ratios of the baffles attached at the top and bottom of each plate.
    Empirical equations for the coefficient of average heat transfer from vertical parallel plates with baffles were obtained.
    Download PDF (1290K)
  • Tadayuki Minoura, Yujiro Sakamoto, Takahiko Suzuki, Shigeki Toyama
    1988 Volume 14 Issue 5 Pages 583-592
    Published: September 10, 1988
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    Distributions of temperature and oxygen concentration in a fluidized-bed refuse incinerator with a capacity of 2000 kg·h-1 and a diameter of 2.1 m were measured by probes during actual operation.
    A numerical three-dimensional simulation model was developed. This model uses the lateral dispersion coefficient of particles and is based on the Two-Phase Theory. Separating refuse into three components (moisture, ash and combustibles), the combustion characteristic was formulated by estimating diameter of combustibles, ignition temperature and transition temperature from reaction to diffusion-dominant region.
    The temperature distribution of emulsion phase and the oxygen concentration distribution in the fluidized bed as calculated were compared with the data obtained from experiments. The calculated results coincided well with the experimental results. The method of modeling and basic and experimental equations in this model were comfirmed to be accurately applicable to numerical calculation. As a result, a foundation of numerical calculation analysis and measurement of the fluidized-bed incinerator was established.
    Download PDF (1491K)
  • Masayuki Toda, Naoki Mogi, Shinobu Yoshikawa, Fumiko Sugano, Hirotaka ...
    1988 Volume 14 Issue 5 Pages 593-600
    Published: September 10, 1988
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    In a draft tube spouted vessel fitted with a gas-liquid injection nozzle, average gas holdup and annulus liquid circulation velocity were measured over a wide range of operating conditions. Flow pattern variations were also observed.
    In the range of lower liquid flow rate, the average gas holdup increased with increasing gas flow rate, but was not affected by liquid flow rate. In the range of higher liquid flow rate, on the other hand, the average gas holdup increased with increases in both gas and liquid flow rates. Relatively uniform fine bubbles were found to be generated by a liquid jet at liquid flow rates beyond the critical spouting velocity. Experimental equations were proposed to predict the average gas holdups. The annulus liquid circulation velocity tended to increase with increasing liquid flow rate, allowing bubbles to be entrained into the annulus of the vessel. It was also found that the liquid circulation velocity first decreased and then, after reaching a minimum value, increased. The effect of gas flow rate on the annulus liquid circulation velocity was significant at low liquid flow rates. The liquid circulation velocity was theoretically analyzed and correlated by using a simple flow model.
    Download PDF (1521K)
  • Masafumi Kuriyama, Eiji Harada, Hirotaka Konno
    1988 Volume 14 Issue 5 Pages 601-608
    Published: September 10, 1988
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    An analogy was proposed between heat and momentum transfer during solid-liquid suspension flow in a circular pipe.
    The analogy was examined by experimental data previously obtained for water suspensions of glass beads and ion-exchange resin particles flowing through vertical pipes. The heat transfer coefficient and temperature profile estimated by the analogy were in good agreement with the observed values and it was concluded that the macroscopic mechanism of heat transfer was elucidated well by the analogy proposed in this work.
    Download PDF (1289K)
  • Akihiro Yamasaki, Hakuai Inoue
    1988 Volume 14 Issue 5 Pages 609-615
    Published: September 10, 1988
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    Surface diffusivities through porous glass in the two-component system of n-hexane and benzene were measured. Experiments were composed of measurements of the permeation fluxes at steady state and of the adsorption equilibrium by the breakthrough method. The observed surface diffusivities of the mixture were enhanced by the accompanying component.
    This enhancement was explained quantitatively by the extended hopping model. In this model, the hopping molecules migrate in the average potential field by three modes of hopping : (1) from naked surface, (2) from adsorbed molecules of the same kind, and (3) from adsorbed molecules of a different kind. Calculated activation energies of hopping of each mode were 0.2-0.4 times the corresponding equilibrium parameters such as heat of adsorption, heat of vaporization, or Wilson parameters in the vaporliquid equilibrium.
    Download PDF (1142K)
  • Tadashi Asahina, Mineo Kosaka, Koji Tajiri
    1988 Volume 14 Issue 5 Pages 616-621
    Published: September 10, 1988
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    A simple transient method of measuring the thermal diffusivities of liquids at elevated temperatures is described. The thermal diffusivity is calculated here on the function of the pulse time from the temperature rise detected with a thin thermocouple placed at some distance below a thin metal plate which is heated electrically for a short period (less than 1 sec) in the sample liquid.
    The thermal diffusivities of molten nitrates of Na, K, Li and Ag were measured successfully by this method after calibrating with distilled water or some organic liquids. It was found that the characteristic diffusivities of these salts were little dependent on temperature.
    Download PDF (1144K)
  • Osamu Miyatake, Hiroyuki Iwashita, Nobuhiro Miura
    1988 Volume 14 Issue 5 Pages 622-629
    Published: September 10, 1988
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    This paper deals with the laminar-flow heat transfer between a square arra of cylinders with a uniform wall temperature and a fluid flowing axially between those cylinders.
    The finite-difference form of the energy equation is solved to obtain the axial variation of cross-sectional temperature distribution by means of a forward-marching, implicit method with iteration, and the numerical results for the local Nusselt number Nuloc and the logarithmic mean Nusselt number Nulm, are presented graphically for the local Graetz number Gzloc or the Graetz number Gz up to 105 and spacing-to-diameter ratios σ of 1.0 to 4.0.
    From the numerical results, approximate expressions suitable for predicting Nuloc and Nulm are derived as functions of σ and Gzloc or Gz.
    Furthermore, the numerical results are compared with those obtained previously for a triangular array of cylinders at the same values of volume fraction of cylinders ε. It is found that, in general, the heat transfer coefficient for the triangular array is larger than that for the square array, especially for the caseε>0.5.
    Download PDF (1185K)
  • Hiroyuki Hatano, Masaru Ishida
    1988 Volume 14 Issue 5 Pages 630-636
    Published: September 10, 1988
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    Tracer gas concentration profiles in and around bubbles and the interphase mass transfer coefficient between bubble and emulsion phases were measured in an incipiently fluidized bed with adsorption and chemical reaction.
    The effluence of tracer gas into the emulsion phase below the bubbles increased with increasing adsorption equilibrium constant and was accompanied by solid particles. On the other hand, tracer gas was observed only in the bubble phase when the reaction rate constant was increased.
    The interphase mass transfer coefficient increased in proportion to the adsorption equilibrium constant within a range from 0 to 1.2. When the reaction occurred, the interphase mass transfer coefficient was proportional to the square root of the reaction rate constant.
    Download PDF (1211K)
  • Noboru Sakai, Tadashi Chida, Teiriki Tadaki
    1988 Volume 14 Issue 5 Pages 637-644
    Published: September 10, 1988
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    Carbon deposition in a nickel pellet resulting from pyrolysis of H2-CO mixture was studied in a range from 873 to 1073K. A nickel pellet reduced with hydrogen was used as catalyst. Rate of carbon deposition and concentration of CH4 and CO2 in the exit gas were measured by thermogravimetry and gas chromatography, respectively.
    Rates of carbon deposition and methanation change very much with the CO mole fraction, yco, in the reactant. At yco =0.25, carbon is hardly produced, and only methanation occurs. On the other hand, at yco above 0.5, carbon is produced on decomposition, and it reduces the rates of carbon deposition and methanation.
    A reaction model including the carbon deposition, methanation and water-gas shift reaction was proposed. In this model the rate expressions derived from a Langmuir-Hinshelwood type mechanism were used. The calculated results agreed well with the experimental ones.
    Download PDF (1070K)
  • Tadayuki Minoura, Yujiro Sakamoto, Kimio Hashimoto, Shigeki Toyama
    1988 Volume 14 Issue 5 Pages 645-654
    Published: September 10, 1988
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    To ascertain the characteristics of heat transfer between particles and fluid in packed or moving beds in which the particles are segregated according to such non-uniformities as size, solidity and initial temperature, a two-dimensional packed-bed model that makes it possible to consider the channelling of fluid was constructed and applied to such sinter coolers.
    The model was used to investigate the effect of each non-uniformity on heat transfer performance, with the following results : 1) The apparent heat transfer capacity coefficient of packed beds with size segregation, as calculated on the basis of random numbers, is as low as 19% of that obtained for beds packed uniformly with particles of the harmonic mean diameter. 2) The initial fluid temperature at the outlet is variable owing to initial particle temperature distribution made by random number. 3) An interactive effect results when there is size segregation combined with initial temperature distribution. 4) The apparent heat transfer capacity coefficient becomes smaller in cases where the solidity of small particles is larger and that of large particles is smaller.
    The numerical simulation results from this non-uniformity model coincided much more closely with the measured results than did those from the uniform harmonic diameter model, owing to the drop of heat transfer capacity coefficient according to size segregation and initial temperature distribution. Although more information about the relations among solidity, particle size and initial particle temperature, etc. is necessary to clarify the difference between the numerical simulation results and the measured ones, a foundation for estimating the heat transfer capacity coefficient of non-uniform packed and moving beds quantitatively has been established in this study.
    Download PDF (1452K)
  • Hideto Yoshida, Makoto Minooka, Hiroaki Masuda
    1988 Volume 14 Issue 5 Pages 655-662
    Published: September 10, 1988
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    Experimental and theoretical studies of particle deposition on a surface composed of different materials (copper and polyethylene) were conducted. Deposition of charged aerosol particles was affected by a localized electrostatic field created by the contact potential difference between the metal (copper) and the dielectric material (polyethylene), and the particles charged with positive polarity deposited mainly on the polyethylene surface, which was charged with negative polarity. This fact suggests that the deposition is caused by the Coulombic force between the surface and the particles. The deposition flux was larger for smaller particles because of the larger effect of the electrostatic field.
    Aerosol particles with negative polarity do not deposit on the polyethylene surface because the surface charge is negative. The deposition is, however, enhanced on the neighboring copper surface. This is explained by the fact that the electrostatic field vector directs to the main stream.
    It is found that the agreement between calculated results and experimental data is better for the case of assuming intrusion of the electric charge into the polyethylene than for that of assuming fixed interface charge.
    Download PDF (5705K)
  • Yoshiyuki Bando, Michio Kuraishi, Makoto Nishimura, Makoto Hattori, Ko ...
    1988 Volume 14 Issue 5 Pages 663-669
    Published: September 10, 1988
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    In a bubble column equipped with a draft tube, the wall of which was partially or totally perforated, the flow pattern, liquid mixing time, gas holdup and specific gas-liquid interfacial area were experimentally studied. The factors affecting the flow characteristics in the column were diameter and length of the draft tube, fractional length of the perforated part, pore diameter of hole, and opening area fraction of the perforated part of the draft tube.
    Part of the liquid and gas flowed radially through the perforated holes of the draft tube, and gas bubbles were disintegrated thereby. In the annular section, fine bubbles encountered a descending gas-liquid flow, creating a violent mixing. The liquid mixing time in a bubble column with perforated draft tube was much shorter than in that with an unperforated draft tube or without a draft tube. The decrement degree of liquid mixing time was strongly dependent on the fractional length of the perforated part.
    Installation of the perforated draft tube increased the specific gas-liquid interfacial area while decreasing the gas holdup compared with the unperforated draft tube.
    Download PDF (1070K)
  • Ken Toyokura, Masahira Ito, Toshio Sawada, Mario Ishiyama, Yasuo Yamaz ...
    1988 Volume 14 Issue 5 Pages 670-675
    Published: September 10, 1988
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    70 to 100 mol% benzene-cyclohexane liquid mixture was compressed to a pressure higher than the equilibrium pressure at 283.2K and 293.2K. The metastable zone expressed by the pressure was turned out to range from 20.7 to 40.4 MPa based on the observation of nucleation within thirty minutes after the mixture was compressed to the desired pressure.
    Benzene crystals of uniform size were obtained when benzene nuclei generated in 90 mol% benzene-cyclohexane mixture at 283.2K were kept in the metastable zone.
    Download PDF (941K)
  • Ryuzo Ito, Yushi Hirata, Kei Sakata, Hironao Wada
    1988 Volume 14 Issue 5 Pages 676-684
    Published: September 10, 1988
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    Development of velocity and concentration fields was investigated for turbulent air flow in a porous tube with carbon dioxide gas injection. From the variations of shear stress and diffusion flux in the flow direction in addition to those of velocity and concentration, it was found that the flow was fully affected up to the tube center in a region more than fifteen times the diameter downstream from the entrance, where the velocity and concentration became self-similar. Mixing length for momentum and that for mass are increased in the wall region but decreased in the core region by the permeate flux injected through the porous wall. In the wall region, mixing length for momentum can be correlated with van Driest's damping expression by introducing local shear stress and local physical properties. The turbulent Schmidt number, on the other hand, is not affected by the permeate flux, for which a simple correlation is presented. The expressions for mixing length and turbulent Schmidt number obtained in this study may be applied to the estimation of characteristics of flow and mass transfer in the membrane module.
    Download PDF (1670K)
  • Yukio Nakanishi, Masao Kobari
    1988 Volume 14 Issue 5 Pages 685-689
    Published: September 10, 1988
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    To obtain the pore-size distributions of contractive tobacco material, tobacco samples of various water content were dried by critical-point drying and pore-size distributions were measured by N2 adsorption isotherms. From these pore-size distributions, the adsorption equilibria of weter on tobacco were calculated. The calculated values agreed well with experimental adsorption data. It was found that critical-point drying prevented the contraction of tobacco. This method is therefore suitable for pretreatment in measuring the pore-size distribution by N2 adsorption isotherm. As a result of this measuring, it was also found that micropores of 1-2 nm radius increased remarkably with increasing water content.
    Download PDF (1096K)
  • Masato Tanaka, Kazuhiko Hosogai, Masaki Tanaka, Eiji O'shima
    1988 Volume 14 Issue 5 Pages 689-692
    Published: September 10, 1988
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    Suspension polymerization of styrene was performed with a forward-reverse mixing method. Size distributions and mean sizes of polymer particles formed under various operating conditions were measured.
    The results were compared with those obtained by conventional mixing and it was found that forward-reverse mixing gave polymer particles of more uniform size.
    Download PDF (717K)
  • Takaji Akiya, Masaru Oowa, Masaru Nakaiwa, Shigetake Kawasaki
    1988 Volume 14 Issue 5 Pages 692-695
    Published: September 10, 1988
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    Crystallization tests of the hydrates of flon-12, flon-11 and flon-21 were carried out.
    The degree of supercooling (the difference between the critical decomposition temperature and the crystallization temperature of the gas hydrate) was decreased with decreasing aging temperature at which the flon-water mixtures were kept with agitation for a given period before cooling. The aging period did not affect the degree of supercooling. The agitation rate seemed to have no effect on it. The relationship between the degree of supercooling and the aging temperature was determined.
    Download PDF (686K)
  • Noriaki Kaneki, Hiromitsu Sakai, Kennosuke Yokota, Takao Takeuchi, Koj ...
    1988 Volume 14 Issue 5 Pages 695-698
    Published: September 10, 1988
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    It was proposed that a precise thermostat used for an enzyme thermistor could be easily and accurately controlled by a microcomputer. The enzyme thermistor using the thermostat determined guaiacol, which is useful as a medicine. The temperature of the thermostat was controlled by means of a method of supervision with a short sampling period. The result demonstrated that the thermostat was controlled to an accuracy of ± 10-4K. In the pH 4.0 to 9.5 region the concentration of guaiacol was determined with the enzyme thermistor in the range of 0.1100mM. The temperature response was stable during the course of 500 runs with 10mM guaiacol.
    Download PDF (724K)
  • Chiaki Igarashi
    1988 Volume 14 Issue 5 Pages 698-702
    Published: September 10, 1988
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    The relationship between strength of a gravitational filter cake and dewatering characteristics of a filter belt press was investigated for municipal sewage sludge. Two kinds of conditioning methods were used : (i) addition of a high-molecular weight cationic polyelectrolyte and (ii) addition of a low-molecular weight cationic polyelectrolyte and a high-molecular weight anionic polyelectrolyte in series.
    The following results were obtained :
    (1) To increase the strength of the gravitational filter cake and also to decrease the moisture content of the compressed cake, dosages of all polyelectrolytes had to be controlled at the break points for each polyelectrolyte.
    (2) The moisture content of compressed cake (m) decreased with increasing strength of the gravitational filter cake. The relationship between m and the strength varied with conditioning method. It also appeared that another, unknown, factor had a large effect on m.
    Download PDF (889K)
  • Hua Liang, Tatsuo Tanaka
    1988 Volume 14 Issue 5 Pages 702-705
    Published: September 10, 1988
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    By using experimental data from many published papers, a new Polanyi equation turns out to be applicable to a more extensive series of materials than the empirical equations so far proposed for the chain propagation reactions in the autoxidation of organic compounds in solution. A first attempt is made to investigate the possible interrelationship between the frequency factors and the organic structure around the hydrogen atom to be abstracted. In consequence, the Arrhenius parameters of the chain propagation in autoxidation can satisfactorily be predicted from the structure of the organic compounds in question.
    Download PDF (651K)
  • Yoshio Iwai, Masayuki Yamashita, Kouhachi Kohashi, Yasuhiko Arai
    1988 Volume 14 Issue 5 Pages 706-711
    Published: September 10, 1988
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    The infinite dilution activity coefficients of C6 hydrocarbons (hexane, 3-methylpentane, cyclohexane and benzene) in heavy paraffinic hydrocarbons (hexadecane and eicosane) were measured in the region 2080°C by using a gas stripping method. The UNIFAC-FV model was applied to calculate the infinite dilution activity coefficients. Those of hexane and 3-methylpentane are predicted sufficiently by the model. Further, those of cyclic compounds such as cyclohexane or benzene can be correlated by adjusting the shape parameters in the combinatorial term.
    Download PDF (1075K)
  • 1988 Volume 14 Issue 5 Pages e1a
    Published: 1988
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    Download PDF (187K)
  • 1988 Volume 14 Issue 5 Pages e1b
    Published: 1988
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    Download PDF (187K)
  • 1988 Volume 14 Issue 5 Pages e1c
    Published: 1988
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    Download PDF (187K)
  • 1988 Volume 14 Issue 5 Pages e1d
    Published: 1988
    Released: November 22, 2010
    JOURNALS FREE ACCESS
    Download PDF (187K)
  • 1988 Volume 14 Issue 5 Pages e1e
    Published: 1988
    Released: November 22, 2010
    JOURNALS FREE ACCESS
    Download PDF (187K)
feedback
Top