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Volume 32 (2006)
- Issue 6 Pages 465-
- Issue 5 Pages 385-
- Issue 4 Pages 315-
- Issue 3 Pages 207-
- Issue 2 Pages 103-
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Predecessor
Volume 32, Issue 3
Displaying 1-18 of 18 articles from this issue
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Transport Phenomena and Fluid Engineering
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Hiroyuki Kawasaki, Tatsumi Yamamoto, Isuru Seekkuarachchi, Hidehiro Ku ...2006 Volume 32 Issue 3 Pages 207-210
Published: 2006
Released on J-STAGE: June 20, 2006
JOURNAL RESTRICTED ACCESSAverage gas holdup, φ, and liquid mixing time, tM, were experimentally investigated in a bubble column (0.32 m i.d.) equipped with perforated plates having four types of hole arrangements. Each plate had 88 holes of 0.5 mm in diameter, which were arranged as follows;
Type A: regular triangle (pitch=30 mm)
Type B: regular triangle (pitch=7 mm)
Type C: equal intervals on concentric circles of 0.256 m and 0.288 m in diameter
Type D: regular triangle (pitch=10 mm) leaning against the column wall
The unaerated liquid height was 0.64 m in all runs. For the four types of perforated plates, the measured values of φ increased with increasing superficial gas velocity, uG0. The hole arrangement strongly influenced φ. For the entire range of uG0 covered in this study, the highest values of φ were obtained with the perforated plate of Type C, and the smallest values were obtained with Type D. However, the hole arrangement had no effect on the values of tM, which were almost constant under the experimental conditions employed.View full abstractDownload PDF (261K) -
Hideki Tokanai, Eiji Harada, Masafumi Kuriyama2006 Volume 32 Issue 3 Pages 211-214
Published: 2006
Released on J-STAGE: June 20, 2006
JOURNAL RESTRICTED ACCESSThe effect of liquid viscosity on pressure drop and turbulent transition was experimentally investigated for solid-liquid downward flow.
Plotting of friction factor against Reynolds number, both of which were defined by using liquid superficial velocity, was examined as a method to evaluate the effect of liquid viscosity on pressure drop. The friction factor correlated well with the Reynolds number. Based on the friction factor versus Reynolds number plots, empirical correlation equations were proposed for friction factor and laminar-turbulent transition Reynolds number, respectively.View full abstractDownload PDF (474K)
Particle Engineering
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Tsuyoshi Inoue, Junya Kano, Fumio Saito2006 Volume 32 Issue 3 Pages 215-219
Published: 2006
Released on J-STAGE: June 20, 2006
JOURNAL RESTRICTED ACCESSAgricultural vinyl sheet was chosen as a model of flexible polyvinyl chloride (PVC), and samples with and without plastisizer (phthalic acid ester (FAE)) were prepared. Each sample was mixed with NaOH pellets at a different Na/Cl ratio and the mixture was subjected to grinding in air by using a planetary ball mill to investigate the influence of FAE on the mechanochemical (MC) dechlorination reaction between PVC and NaOH. The FAE prevents the MC reaction, but the degree of dechlorination is significantly improved as the Na/Cl molar ratio is increased. The MC reaction itself is independent of FAE, which does not dissolve in the aqueous phase.View full abstractDownload PDF (693K) -
Satoshi Ishikawa, Atsuko Shimosaka, Yoshiyuki Shirakawa, Jusuke Hidaka2006 Volume 32 Issue 3 Pages 220-226
Published: 2006
Released on J-STAGE: June 20, 2006
JOURNAL RESTRICTED ACCESSThe mechanism of sieving for needle-like particles was analyzed to perform the shape separation by sieving.
First, the effects of vibration conditions and particle shape on sieving rate were investigated by using model particles having an ideal cylindrical shape. In the case of vertical vibration, the effect of particle length on sieving rate was small, and particles were mostly oriented in the vertical direction, then separated by their diameter. On the other hand, the sieving rate decreased as the particles became longer, and so particles were separated by their length in horizontal vibration. The separation length was determined by the elevation angle between particles and the sieve surface, and the opening size. This elevation angle depended on the particle velocity on the sieve.
Second, bamboo fibers, as an example of real needle-like particles, were sieved for their shape separation. The distribution of fiber breadth followed the lognormal distribution. By approximating the particle shape to a round edge quadratic prism, the separation sizes (breadth, thickness) were estimated by the shape index. Separation according to the particle length was also possible by sieving under the appropriate conditions.View full abstractDownload PDF (1170K) -
Satoshi Ishikawa, Yuichi Yoshida, Atsuko Shimosaka, Yoshiyuki Shirakaw ...2006 Volume 32 Issue 3 Pages 227-235
Published: 2006
Released on J-STAGE: June 20, 2006
JOURNAL RESTRICTED ACCESSSieving rate was estimated based on the particle percolation model, which comprises three probability models for (i) a vibrating particle bed, (ii) the boundary between particle bed and sieve surface, and (iii) sieve openings. It was assumed that the vibrating particle bed is formed from a simple cubic lattice, and the percolation probability of undersized particles throughout the particle bed is represented as a function of porosity. The porosity variation mechanism was elucidated by simulation, and the effects of undersized-particle concentration were elucidated by experiments. Subsequent particle behaviors on the sieve surface were analyzed in order to obtain the passage probability of undersized particles through the boundary between the particle bed and the sieve surface. Additionally, in order to obtain more accurate passage probability of the undersized particles through the sieve openings, effects deriving from vibration conditions were taken into account. As a result, the estimation equation comprising these three probability models was found to allow prediction of sieving rate under the operating condition that the mass ratio of such undersized particles is 10 percent or smaller.View full abstractDownload PDF (1163K)
Separation Engineering
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Tomio Mimura, Hidehiro Kumazawa, Yasuyuki Yagi, Toru Takashina, Ryuji ...2006 Volume 32 Issue 3 Pages 236-241
Published: 2006
Released on J-STAGE: June 20, 2006
JOURNAL RESTRICTED ACCESSThe kinetics of the reaction of CO2 with 6 kinds of chemical absorbents were investigated at 298 K. The experiments were performed in a stirred vessel with a horizontal interface which appeared to be completely smooth. Tested absorbents were 2-amino-2-methyl-1-propanol (AMP), KS-1 absorbent, monoethanolamine (MEA), methylaminoethanol (MAE), methyldiethanolamine (MDEA) and Diethanolamine (DEA). MAE and KS-1 absorbent showed good kinetic characteristics, which were found to be higher than those for conventional MEA absorbent.
A simple method for calculating rate constants was also studied. Physical absorption experiments are generally necessary to evaluate reaction rate constants of alkanolamines. In this research, a method for calculation of reaction rate constants has been proposed without these relatively complicated experiments. However, this calculation method can be applied only for amines with molecular weights of 60–120 and liquid concentrations of less than 1.4 kmol·m−3.
The values of the rate constant for MAE and KS-1 absorbents at 298 K were evaluated to be 4.71×103 m3·kmol·s−1 and 7.99×103 m3·kmol·s−1, respectively, which were higher than that of MEA (3.63×103 m3·kmol·s−1).View full abstractDownload PDF (332K) -
Masaaki Sekino, Yoichi Matsui, Nobuya Fujiwara2006 Volume 32 Issue 3 Pages 242-245
Published: 2006
Released on J-STAGE: June 20, 2006
JOURNAL RESTRICTED ACCESSWe previously presented a FCP model that showed good fit with a wide range of actual performance data on a hollow fiber reverse osmosis module.
However, this analytical model contained the anomaly that the simulated boundary layer thickness is larger than the apparent length of the clearance among hollow fibers. Here, we propose a hollow fiber faggot model that is consistent with the features of the hollow fiber arrangement of the practical reverse osmosis module. As a result of verifying this model, it was confirmed that the boundary layer thickness on the surface of the faggot is smaller than the length of clearance between the faggots of hollow fibers.View full abstractDownload PDF (313K)
Thermal Engineering
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Taro Sakata, Tetsuya Iwase, Shinji Kambara, Hiroshi Moritomi2006 Volume 32 Issue 3 Pages 246-252
Published: 2006
Released on J-STAGE: June 20, 2006
JOURNAL RESTRICTED ACCESSThe effective thermal conductivity of the particle layer between heat exchanger tubes and their wastage covers was measured by using a 2 MWth pressurized fluidized bed test rig to design in-bed heat exchanger tubes with wastage covers in pressurized fluidized bed combustors. Heat exchanger tubes with wastage covers having two different gap lengths and without wastage covers were prepared. An increase of the gap length increased not only the loading rate of in-gap particles but also the effective thermal conductivity of the particle layer. The effective thermal conductivity of the particle layer over a wide range of particle temperature was investigated by use of a laboratory scale effective thermal conductivity test rig and an atmospheric pressure bubbling fluidized bed combustor. It was found that the effects of gap length on the effective thermal conductivity of the particle layer can be predicted by a modified Kunii-Smith's empirical equation for estimation of the effective thermal conductivity in a packed bed. The shape factor in the equation, β, is taken as 3.4 for estimation of the effective thermal conductivity of the in-gap particle layer in pressurized fluidized bed combustors.View full abstractDownload PDF (715K) -
Kazushige Nakao, Eiichi Ozaki, Tsuneo Yumikura, Masaki Ikeuchi, Goro Y ...2006 Volume 32 Issue 3 Pages 253-261
Published: 2006
Released on J-STAGE: June 20, 2006
JOURNAL RESTRICTED ACCESSCharacteristic analysis was conducted for a LiBr–H2O vertical liquid film absorber installed with bare tubes, corrugated tubes or tubes with spirally wound fir-fins, the outer diameter of which is 12 mm. Calculation of local distributions of temperature and concentration of a falling LiBr aqueous solution and the absorption rate of water vapor into it showed that the fir-finned tube is superior to the other tubes. In addition, the effect of installation of multiple tubes was investigated under the condition of the total tube length of 4 m. The usage of one long tube without subdivision was found to give maximum values of heat generation and absorption rate of water vapor. Effects of vapor temperature and inlet temperature of cooling water circulating inside the tube were investigated for the tube with spiral fir-fins. Heat output, absorption rate of water vapor and heat output temperature increase linearly with an increase in the vapor temperature or a decrease in the temperature of circulating cooling water. The boost temperature as an increase of heat output temperature from the vapor temperature decreases with increasing the vapor temperature. It was confirmed that the LiBr–H2O heat transformer installed with fir-finned tubes will be able to generate heat output with boost temperature of 20–30 K when it is operated under the normal conditions of vapor temperature and/or inlet temperature of circulating cooling water.View full abstractDownload PDF (966K) -
Kazushige Nakao, Eiichi Ozaki, Tsuneo Yumikura, Masaki Ikeuchi, Goro Y ...2006 Volume 32 Issue 3 Pages 262-268
Published: 2006
Released on J-STAGE: June 20, 2006
JOURNAL RESTRICTED ACCESSHeat transfer experiments were conducted to investigate fin efficiency and heat transfer enhancement for a vertically falling liquid film flow on a spirally wound fir-finned tube. A spirally wound fir-finned tube of outer diameter of 12 mm with a double-stacked fin has a fin efficiency of 0.14, which is almost constant irrespective of the falling film flow rate. With this fin efficiency, the heat transfer area of the fir-finned tube is enlarged to twice the base area. The heat transfer coefficient of the fir-finned tube, which is defined on the basis of the actual area, is about 2 to 3 times the heat transfer coefficient of a bare tube. Particularly large heat transfer enhancement was attained in the region of low Reynolds number. Based on a network model for the heat transfer from the fluid flowing inside the fir-finned tube to the falling film, it has been shown that decrease in contact heat resistance between fir-fin and tube has a large effect on the enhancement of film heat transfer.View full abstractDownload PDF (1068K) -
Yohsuke Matsushita, Atsunobu Koyama, Kosei Sugawara, Yoshio Morozumi, ...2006 Volume 32 Issue 3 Pages 269-273
Published: 2006
Released on J-STAGE: June 20, 2006
JOURNAL RESTRICTED ACCESSThis paper presents a procedure for calculation of temperature from mole fractions of chemical species and enthalpy, which are obtained from conservation equations of thermo fluid dynamics simulation. Fifteen chemical species that are often taken into account in gas and pulverized combustion simulation were investigated: N2, O2, CO, CO2, H2, H2O, SO2, H2S, CH4, C2H2, C2H4, C2H6, C3H4, C3H6 and C3H8.
When temperature is calculated from mole fractions of chemical species and enthalpy, a large error is involved if heat capacity is assumed to be constant. Thus, the equation expressing the relationship between enthalpy and temperature, derived by integrating the approximation of heat capacity with respect to temperature, should be used to obtain the temperature with high precision.
When heat capacity is approximated by a quadratic or cubic polynomial with respect to temperature, the polynomial approximation expressing the relationship between enthalpy and temperature is cubic or a fourth degree polynomial approximation. A non-iterative solution such as the Cardano method or the Ferrari method is available for the solution of the cubic or fourth degree polynomial approximation in a temperature calculation procedure.
When heat capacity is approximated by a fourth or higher degree polynomial approximation with respect to temperature, an iterative method such as the Newton method is necessary to solve temperature. The higher the degree of the polynomial approximation is, the higher the computational load becomes. The computational load of the non-iterative method is the same as that of the iterative method when the degree of the enthalpy as a function of temperature is the fourth.View full abstractDownload PDF (275K)
Chemical Reaction Engineering
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Takafumi Sato, Hiroyuki Yokoyama, Hideaki Miki, Naotsugu Itoh2006 Volume 32 Issue 3 Pages 274-280
Published: 2006
Released on J-STAGE: June 20, 2006
JOURNAL RESTRICTED ACCESSDehydrogenation of cis-3-hexen-1-ol with CuO/ZnO catalyst in a fixed-bed catalytic reactor was examined from 438 to 458 K as a model reaction of dehydrogenation of unsaturated alcohols. The main products were cis-3-hexenal, 1-hexanol and hexanal. The reaction pathways were as follows: 1) dehydrogenation of cis-3-hexen-1-ol to form 3-hexanal, 2) hydrogenation of cis-3-hexene-1-ol with hydrogen derived from dehydrogenation to give 1-hexanol, 3) hydrogenation of cis-3-hexenal, 4) dehydrogenation of 1-hexanol. Reactions 3) and 4) yielded hexanal, which was the major product, with yields of up to about 80%. Calculation of the equilibrium of this reaction system by estimation of the thermodynamic properties of cis-3-hexen-1-ol and cis-3-hexenal, which properties have not been reported, revealed that hexanal was very stable in this temperature region and agreed with the experimental results. The rate constant for this reaction was correlated with a reaction model that be able to reproduce the experimental data at 438–458 K.View full abstractDownload PDF (454K) -
Hiroshi Obuse, Masaaki Wakita, Satoshi Nakayama, Kiyoyuki Kitano, Yasu ...2006 Volume 32 Issue 3 Pages 281-287
Published: 2006
Released on J-STAGE: June 20, 2006
JOURNAL RESTRICTED ACCESSOxidation characteristics of nitrogenous compounds in supercritical water in a commercial-scale downflow type reactor were investigated using a simulant of industrial waste containing high concentrations of nitrogenous compound and inorganic salts. N,N-Dimethylacetamide was used as the model of nitrogenous compounds in industrial waste. Increase of reaction temperature or air ratio was effective for decreasing concentrations of ammonium and cyanide ions, which were the main residual nitrogen compounds in effluent, under the following reaction conditions: temperature 642°C, pressure 23.44 MPa, air ratio 1.2, and waste flow rate 6.5 kg/min (residence time about 10 sec). The effect of air ratio was particularly remarkable, and all the analysis data (TOC, NH4+, CN−, NO2−, and NO3−) fell below the detection limit at the temperature of 654°C and air ratio of 1.3. It was also found that an optimum waste flow rate (5.1 kg/min) exists that minimizes the concentration of residual nitrogen compounds in liquid effluent. Ammonium and cyanide ions are the main residual nitrogen compounds in liquid effluent at higher waste flow rate (6.5 kg/min), and nitrite and nitrate ions are the main ones at lower waste flow rate (4.1 kg/min). Furthermore, it was found that presence of inorganic salts in wastewater promoted the decomposition of ammonium and cyanide ions.View full abstractDownload PDF (517K)
Biochemical, Food and Medical Engineering
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Takashi Sato, Masahito Taya2006 Volume 32 Issue 3 Pages 288-292
Published: 2006
Released on J-STAGE: June 20, 2006
JOURNAL RESTRICTED ACCESSPhotocatalytic inactivation tests were conducted on TiO2 suspensions containing bacteriophage MS2 under the irradiation from a black-light fluorescent lamp in the presence of glucose or ethanol as a model impurity. In the absence of impurity, the semi-logarithmic plot of relative phage titer decreased linearly obeying a first-order reaction, while the addition of glucose or ethanol gave plots with curved profiles of decreasing phage titer. These results suggest that the presence of organic impurity changes the kinetics of the photocatalytic phage inactivation. The profiles of phage titer during the photoreaction could be kinetically analyzed by applying a series-event model. Estimating the kinetic parameters (lethal number, n, and apparent inactivation rate constant, k′) obtained from the applied model, it was found that an increase in the concentration of organic impurity resulted in an increase in n value and a decrease in k′ value. It was considered that the organic molecules are adsorbed on the surfaces of phage particles and function as scavengers of oxidative radicals (OX), and as protectors for the phage surfaces against oxidation by OX. This consideration was supported by the finding that an elevation of reaction temperature (T=283–313 K) in the presence of glucose resulted in reduction of n value as well as enhancement of k′ value.View full abstractDownload PDF (618K)
Micro and Nano Systems
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Hidetoshi Nagamoto, Yosuke Kobayashi, Junichiro Otomo, Eiji Oshima2006 Volume 32 Issue 3 Pages 293-296
Published: 2006
Released on J-STAGE: June 20, 2006
JOURNAL RESTRICTED ACCESSThe friction factors for microchannels of 200 μm×200 μm and 500 μm×200 μm were obtained by measuring the pressure drops in the channels. The measured values were in a good agreement with ones predicted theoretically for Reynolds number, Re ranging from 5 to 100.
The laminar flow profiles measured with polystyrene microbeads at a half of the channel depth also agreed well with the theoretical profiles for Re=0.0238 and 0.0369.View full abstractDownload PDF (485K)
Materials Engineering and Interfacial Phenomena
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Yoshitaka Matsuyama, Seigo Kotera, Takashi Shibuya, Masatoshi Nagai2006 Volume 32 Issue 3 Pages 297-302
Published: 2006
Released on J-STAGE: June 20, 2006
JOURNAL RESTRICTED ACCESSThe lifetime of single-layer resin spacer type insulating glass was predicted on the basis of calculation of the transmission coefficient of water vapor adsorbed in drying materials (zeolite 4A and talc) of the resin spacer, in order to optimize drying materials in the resin spacer for increased lifetime. When the composition of the zeolite added was 20 wt%, the transmission coefficient of water vapor showed a minimal value of 1.0×10−19 (g·cm·cm−2·sec−1·Pa−1) at 40°C and 95%RH. At 25°C and 50%RH, the time required for resin spacer to reach saturation in 3 mm layer was 55000 h (2291 days, 6.28 years) as calculated. When the composition of the zeolite added was 20 wt% or less, the water vapor transmission coefficient showed a positive correlation with temperature, but above 30 wt%, it showed a negative correlation. For a talc sample, the transmission coefficient of water vapor was unchanged but the saturation amount of resin spacer increased.View full abstractDownload PDF (678K)
Environment
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Shinji Yasui, Yuzo Shirai, Makoto Nunokawa, Tadashi Amakawa2006 Volume 32 Issue 3 Pages 303-309
Published: 2006
Released on J-STAGE: June 20, 2006
JOURNAL RESTRICTED ACCESSTo develop a dry recovery process for fluorides including the decomposed gases of SF6 gas, which has a global warming potential (GWP) of 23,900 times that of CO2, the gas–solid reaction properties of HF gas and calcium carbonate in a fixed-bed reaction furnace were investigated.
The experimentally determined reaction zone volume including unreacted calcium carbonate in the fixed-bed reaction furnace was in good agreement with the estimated value from the HF breakthrough curve using the fixed-bed reaction model. Further the HF reaction rate with calcium carbonate could be estimated from an approximate rate formula using the unreacted core model with the mass transfer factors of the solid product layer and the boundary layer at the external surface, and each factor was obtained. By estimating roughly the passage time through the reaction zone in the furnace from the obtained reaction rate formula and these factors, the reaction zone volume, which is needed to design the reaction vessel in the fixed-bed reaction furnace, can be estimated safely.View full abstractDownload PDF (1127K) -
Wataru Minami, Hee-Joon Kim2006 Volume 32 Issue 3 Pages 310-313
Published: 2006
Released on J-STAGE: June 20, 2006
JOURNAL RESTRICTED ACCESSPhotocatalytic decomposition of halocarbons by using TiO2 and a germicidal lamp was studied for the purpose of developing a treatment process to convert halocarbons into harmless substances. The decomposition rates of chlorodifluoromethane (HCFC-22), carbon tetrachloride and methane were analyzed, because these compounds have the same structure but different constituents.
As a result, the decomposition rate was found to be highest for HCFC-22, followed by methane and CCl4 in that order and reactions were first-order within the concentration range used. The activation energies obtained from the overall reaction rate constants were 13.7 kJ·mol−1 for HCFC-22, 66.1 kJ·mol−1 for CCl4 and 16.6 kJ·mol−1 for methane.View full abstractDownload PDF (452K)
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