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Hajime Unno, Fumio Kikuchi, Akinori Matsuura, Takashi Akehata
1981 Volume 7 Issue 1 Pages
1-5
Published: January 10, 1981
Released on J-STAGE: November 12, 2009
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Flow pattern and flow characteristics of spiral flow aeration basin were studied experimentally in the light of the two-region model proposed by the authors.
The size of the bubble-rich region formed by a perforated tube sparjer increased proportionally with air flow rate to the power of 0.3, while that formed by a porous plate diffuser remained constant with respect to air flow rate. The relationship between size of bubble-rich region and setting depth of the air-diffusing unit was approximately linear irrespective of the type of air-diffusing unit.
Although the exchanging liquid flow rate between the two regions was found to be a complicated function of operating and geometrical variables, the flow rate was correlated well by one variable group, i.e., the air flow rate divided by the ratio of bubble volume to mixed volume of bubble-rich region.
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Kiyotaka Sakai, Masaaki Hibi, Koichiro Sasaki
1981 Volume 7 Issue 1 Pages
6-12
Published: January 10, 1981
Released on J-STAGE: November 12, 2009
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Studies of both the gas-liquid mixing zone and of pulse response measurement were carried out to account for the mixing condition of combustion gas and liquid within a submerged combustion apparatus. It was found that the liquid in the apparatus was almost completely mixed and that contact of combustion gas with liquid was satisfactory.
A theoretical analysis of the heat transfer rate in the apparatus is developed to reveal a variation of combustion gas temperature and gas humidity with position. Furthermore, the relationship between volumetric heat transfer coefficient
hGA·α and combustion gas mass velocity in the downcomer tube is derived from experimental data.
The optimum depth of submergence, at which heat transfer between high-temperature combustion gas and liquid was completed, was about 25 cm under the following condition : diameter ratio of downcomer tube to airlift tube =1/2.
If the downcomer tube is lowered to a depth of 25 cm, the pressure drop can be controlled at the minimum value without losing heat transfer efficiency. The submerged combustion apparatus was found to be better suited for evaporation than for heating of liquid.
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Kiyotaka Sakai, Michio Mineshima, Noriaki Saito, Eisuke Tsutsumi, Hiro ...
1981 Volume 7 Issue 1 Pages
13-18
Published: January 10, 1981
Released on J-STAGE: November 12, 2009
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Although submerged combustion apparatus has a very high thermal efficiency, the pressure drop is not small. To reduce this disadvantage, a heat exchanger with direct contact of combustion gas and liquid using dual flow has been developed. It was found to be possible to maintain a very high thermal efficiency, even if the pressure drop was suppressed to less than 1/10 of the usual value. The thermal efficiency was dependent not on hole diameter, but on the ratio of total hole area to column area on the perforated plate. A heat transfer model without mass transfer was devised to obtain an empirical equation for the volumetric heat transfer coefficient, and this model was compared with heat-and-mass transfer model. In this system, condensation occurred in the range of low liquid temperature. The effect of condensation may be ignored due to the small amount of condensation.
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Masao Kobari, Yukio Shimizu, Mihoko Endo, Hikoji Inazumi
1981 Volume 7 Issue 1 Pages
19-25
Published: January 10, 1981
Released on J-STAGE: November 12, 2009
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The contact drying of thin sheets of absorbent cell wall materials was studied experimentally and theoretically.
In a thin sheet, the resistance to transmission in the material phase is negligibly small compared with that in the air phase, and so moisture content and temperature of the material can be considered to be equally distributed during drying. In such cases, drying rates changing continuously could be obtained by considering the equilibrium relation of material and the rates of simultaneous transfer of heat and mass between material and air. The drying rates calculated by means of the analytical method proposed by the authors were in excellent agreement with the experimental ones measured by use of a specially designed wind-tunnel type of hot-surface dryer.
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Masahiro Yorizane, Hideto Yoshida, Nonot Soewarno, Nobuyuki Miyoshi
1981 Volume 7 Issue 1 Pages
26-32
Published: January 10, 1981
Released on J-STAGE: November 12, 2009
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Experimental studies of hydraulic characteristics, i.e. weeping, entrainment, stable operating region and the effect of baffles have been conducted in an air-water system using perforated trays. For the low liquid flow region, the amount of entrainment when the tray oscillates is larger than when the tray does not oscillate, but this trend is reversed for the high liquid flow region. The amount of entrainment increases with the decrease in period of oscillation. If the F-factor is less than 1.0, the amount of weeping when the tray oscillates is larger than when it does not, but this trend is reversed if the F-factor is greater than 1.0.
It is found that the stable operating region in which the tray oscillates becomes smaller than that in which it does not oscillate. From the experimental results, it is found that the optimum number of baffles is two and the optimum baffle height is approximately the same as that of the outlet weit. Using baffles decreases the pressure drop difference. However, there is a small increase in the amount of weeping, entrainment, pressure drop and static liquid seal.
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Hideo Sadotomo, Koreatsu Miyahara
1981 Volume 7 Issue 1 Pages
33-39
Published: January 10, 1981
Released on J-STAGE: November 12, 2009
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A stable, high-speed calculation procedure for multicomponent batch distillation with plate hold-up is presented, based upon the consideration that behavior of batch distillation is represented by several eigenvalues of small absolute value. In this procedure the differential equations are linearized for a relatively large time increment and a similarity transformation is performed on the Jacobian matrix to result in solving an eigenvalue problem of symmetric tridiagonal matrix. It is shown that this eigenvalue method is more than 20 times faster than the Runge-Kutta-Gill method, especially in the mild product period.
A new criterion to estimate the absolute value of the largest negative eigenvalue which governs both the maximum stable time increment and the accuracy of numerical integration techniques is derived. It is also shown that this criterion gives estimated values which agree satisfactorily with experimental ones.
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Noriaki Kaneki, Hiroshi Hara, Koji Shimada, Yoshiteru Jomoto
1981 Volume 7 Issue 1 Pages
40-44
Published: January 10, 1981
Released on J-STAGE: November 12, 2009
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The limiting current density of porous electrode with LaNi
5 catalyst in an alkaline-type H
2-O
2 fuel cell occurs as a consequence of diffusion control of hydroxyl ion to reaction sites in the porous electrode, so that it is greatly influenced by the ratio of Teflon dispersion to LaNi
5 catalyst and the hot-press temperature during preparation.
The cause is attributed to the change in pore structure of the electrode produced by Teflon. It also involves the increase in narrow paths and bottlenecks as a result of the corresponding decrease in pore size and volume.
The addition of aluminum powder to the electrode and its leaching resulted in an increase in pore size and volume and improved the electrode characteristics. A close relationship was found between limiting current density and liquid penetration rate.
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Ken Toyokura, Tetsuo Shibauchi, Makoto Uchiyama, Sho Tokumoto, Shigeyo ...
1981 Volume 7 Issue 1 Pages
45-49
Published: January 10, 1981
Released on J-STAGE: November 12, 2009
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Moving properties of a fluidized needle crystal of calcium sulfate were studied. It was shown that the terminal velocity of a needle crystal was dominantly affected by the diameter of the needle in the range where the crystal's length-to-diameter ratio was 20 to 100 and Reynolds number was 0.4 to 2.2. The correlation among terminal velocity of a needle crystal, superficial velocity and void fraction was obtained.
A new estimation method for the average particle diameter of needle crystals in a fluidized bed crystallizer is proposed from observation of the height of a fluidized bed as an application of the correlation obtained in this study, and crystal growth rate was calculated from the difference of mean particle diameter in the growing period. This crystal growth rate was correlated against 0.7 power of supersaturation.
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Characteristics of p-xylene clathrate
Mitsutaka Kitamura, Eiji Wakabayashi, Tasuku Nakai
1981 Volume 7 Issue 1 Pages
50-56
Published: January 10, 1981
Released on J-STAGE: November 12, 2009
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Tetra- (4-methylpyridino) nickel dithiocyanate was used as metal complex to make a clathrate with
p-xylene.
The solubility of nickel complex in methylcellosolve solution was found to be largely influenced by dissociation. Thus the suppressive effect of 4-methylpyridine on the dissociation was studied.
p-xylene clathrate was formed using batch cooling crystallization in methylcellosolve solution containing
p-xylene, nickel complex and 10 Vol % 4-methylpyridine. It was found that clathrate composition and
p-xylene yield obtained by adductive crystallization are remarkably dependent on initial solution composition.
Furthermore, clathrate was formed by reaction between nickel complex powder and
p-xylene, when solid-liquid equilibrium measurements were carried out to investigate the structure of clathrate in solid phase.
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Applicability of effective absorption coefficient
Tsutao Otake, Setsuji Tone, Kazuyuki Higuchi, Katsumi Nakao
1981 Volume 7 Issue 1 Pages
57-63
Published: January 10, 1981
Released on J-STAGE: November 12, 2009
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The light intensity profiles in a rectangular aerated cell produced by a low-pressure mercury lamp were measured by two Cs-Te photoprobes having quite different angular characteristics. The profiles observed with a less directional photoprobe A in air as a pattern of homogeneous systems were well explained by the diffuse line source model. The effective absorption coefficients were evaluated by fitting the model equation to the profiles measured by probe A for nitrogen bubbles-dispersed potassium nitrate aqueous solution as a pattern of heterogeneous systems. A convenient method was also presented to obtain the coefficients applying the radial light model to the profiles observed with a sharp directional photoprobe B.
The effective absorption coefficient was found to be a unique function of dispersed phase hold-up, particle diameter, specific surface area and the optical properties of each phase, and a simple empirical correlation was obtained.
The observed rates of the photoreduction of potassium ferrioxalate in the presence of nitrogen bubbles agreed well with the results computed using the coefficients for the dispersion.
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Katsuhide Murata, Kenji Sato, Hideo Teshima
1981 Volume 7 Issue 1 Pages
64-70
Published: January 10, 1981
Released on J-STAGE: November 12, 2009
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Experimental work on thermal degradation was done by using a continuous-flow stirred-tank reactor. Kinetic data of the carbon number distribution of volatile products, the molecular weight distribution of reactor contents and the rate of thermal degradation were obtained at a steady state, in the temperature range of 410-440°C under atmospheric pressure.
The observed gas chromatography results show that the volatile materials derived from polyethylene are produced exclusively by unzipping from the chain ends. However, the GPC results show that the reactor contents are the products of random scission. These evidences suggest that the thermal degradation of polyethylene is a simultaneous reaction of unzipping from the chain ends and random scission.
Assuming that the two kind of reaction are simultaneously taking place for thermal degradation of polyethylene, the molecular weight of the reactor contents should increase with the degradation temperature. The observed temperature dependency of average molecular weight of the reactor contents agree with that predicted.
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Masaaki Nakamura, Takashi Tanahashi, Daisaku Takada, Kunihisa Ohsasa, ...
1981 Volume 7 Issue 1 Pages
71-76
Published: January 10, 1981
Released on J-STAGE: November 12, 2009
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Radial effective thermal conductivity and apparent wall heat transfer coefficient in a packed bed with gas-liquid cocurrent upflow were measured in air-water system with three kinds of spherical particles of
dp =4.0, 5.0 and 6.0 mm diameter. The following results were obtained :
1) The effective thermal conductivity,
ker, and wall heat transfer coefficient,
hω, in the cocurrent upflow system are larger than those in the cocurrent downflow system.
2) Increasing the gas flow rate,
G, while holding any constant liquid flow rate,
L, kerand
hω, in the downflow system increase gradually. Those in the upflow system increase temporarily in the bubble-flow region, and then decrease gradually or are constant in the pulse-flow region.
3) In the range of high gas flow rate in which
ker decreases gradually,
ker/kl=c (dpL/μl) a (dpG/μg) b(
a=0.550.57,
b=-0.3,
c=22.526.9)
4) Experimental results of
ker for porous alumina spheres of 5.0 mm diameter are larger by about 20% than the estimated values of
ker for glass spheres of the same size. This suggests that particle surface roughness has an influence on the liquid holdup and on
ker.
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An analysis of the unburned combustibles content in Taiheiyo coal-derived ash
Toshimasa Hirama, Minoru Tomita, Tornio Adachi, Masayuki Horio
1981 Volume 7 Issue 1 Pages
77-82
Published: January 10, 1981
Released on J-STAGE: November 12, 2009
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Mass utilization of coal requires ash disposal or utilization technology which is acceptable to modern society. A simple model is examined in this article for estimating unburned combustibles content in the ash produced from fluidized bed combustion.
Experiments were carried out burning Taiheiyo coal in a 10.8 cm I.D. fluidized bed. Overall combustion rate constant was obtained for coarser fraction, taking into account the particle residence time distribution. Elutriation rate constant was determined from the relation between combustibles content and particle size. The observed elutriation rate constant values were between those from Zenz
et al. and Yagi
et al. correlations.
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Saburo Yashima, Fumio Saito, Hiromitsu Horita
1981 Volume 7 Issue 1 Pages
83-89
Published: January 10, 1981
Released on J-STAGE: November 12, 2009
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Impact crushing of single particles made of eight kinds of brittle materials was carried out by using an impact testing apparatus composed of a double pendulum. Specimens were shaped into spheres having a nominal diameter of 2.0 cm.
The experimental results are summarized as follows : 1) Specific fracture energies were found to be less than those calculated from the equation derived by applying the Hertz theory. 2) The experimental relationship between impulse and specific fracture energy for the glassy materials was found to be in agreement with the theoretical one. For the minerals, however, the experimental values of impulse were found to be greater than the values calculated from the theoretical equation. 3) New surface produced could be calculated by three parameters consisting of the Gaudin-Meloy-Harris (G-M-H) size distribution equation. These parameters were found to be also represented as the function of impact energy. 4) The energy law was found to be similar to the final fineness limit theory proposed by T. Tanaka. 5) The crushing efficiency under impact loading was found to be better than that under static loading for gypsum, but both efficiencies were found to be nearly equal for the other kinds of samples.
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Michiharu Toh, Yasuhiro Murakami
1981 Volume 7 Issue 1 Pages
90-95
Published: January 10, 1981
Released on J-STAGE: November 12, 2009
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Normal and shear forces on a fluid-loaded hinged scraper blade were calculated by the stream function shown in the previous reports. Power consumption of the blade was obtained theoretically on the basis of the equilibrium condition of those forces.
When the scraper angle, or the number or the width of the blades was changed, the theoretical power consumption of the blade was compared with the experimental results and agreed fairly well with them.
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Toyomitsu Shimizu, Osamu Imai, Yasuhito Sakakibara, Tetsuya Ohrui
1981 Volume 7 Issue 1 Pages
96-101
Published: January 10, 1981
Released on J-STAGE: November 12, 2009
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Using the dispersion flow-diffusion reaction model, the stability of atmospheric-pressure ammonia burners was studied.
The conditions for ignition and extinction were analytically determined for different feed conditions.
Rearranging the above results, the ignition and extinction temperature diagram is constructed and the regions of stable operation are estimated. With this diagram, safe start-up and proper change of operating condition can be established.
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Atsushi Endo, Hiroshi Utsugi, Mutsumi Suzuki, Shigemori Ohtani, Koei K ...
1981 Volume 7 Issue 1 Pages
102-108
Published: January 10, 1981
Released on J-STAGE: November 12, 2009
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