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Volume 35, Issue 3
Displaying 1-13 of 13 articles from this issue
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Transport Phenomena, Fluid Mechanics and Mixing
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Rachid Chebbi, Abubakr M. Abubakr, Abdulrahman Y. Al-Abdul Jabbar, Abd ...Article type: Short Communications
Subject area: Transport Phenomena, Fluid Mechanics and Mixing
2002 Volume 35 Issue 3 Pages 304-308
Published: 2002
Released on J-STAGE: June 26, 2002
JOURNAL RESTRICTED ACCESSA new experimental technique is proposed for the study of axisymmetric spread of oil on water. The technique is applied to study the viscous-gravity stage in which oil is spilled on water at a constant rate. Results are found to be in good agreement with the order-of-magnitude analysis. An expression for the spreading law is determined, and the accuracy of using the theoretical constant-volume spreading-law to estimate the spreading-law prefactor for the steady-discharge case is analyzed.View full abstractDownload PDF (494K) -
Shigenori Togashi, Takashi Ohta, Hitoshi AzumaArticle type: Short Communications
Subject area: Transport Phenomena, Fluid Mechanics and Mixing
2002 Volume 35 Issue 3 Pages 309-312
Published: 2002
Released on J-STAGE: June 26, 2002
JOURNAL RESTRICTED ACCESSThe thinning rate of the remaining liquid film on rotating substrates with different static contact angles was measured. It was found that the thinning rate of a liquid film increased when the static contact angle between the liquid and the substrate increased. Emslie’s equation was modified to account for the effect of the static contact angle. Then it was shown that the thinning rate of the remaining liquid film predicted by the modified Emslie equation agreed well with the measured thinning rate. It is therefore concluded that we can use the equation to determine the appropriate processing time for blowing away a liquid film at a static contact angle.View full abstractDownload PDF (424K)
Catalysis, Kinetics and Reactor Design
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Suttichai Assabumrungrat, Kobkan Suksomboon, Piyasan Praserthdam, Tomo ...Article type: Research Papers
Subject area: Catalysis, Kinetics and Reactor Design
2002 Volume 35 Issue 3 Pages 263-273
Published: 2002
Released on J-STAGE: June 26, 2002
JOURNAL FREE ACCESSMathematical models taking into account the non-isothermal condition and radial heat and mass transfer for the dehydrogenation of ethylbenzene to styrene in a conventional fixed-bed reactor and a palladium membrane reactor were developed using the kinetic data of a 70 wt% F2O3:20 wt% K2O:5 wt% Ce2O:5 wt% Cr2O3 catalyst and the H2 permeation data through a palladium membrane with 10 μm thickness. The study showed that due to the continuous removal of H2 from the reaction side, both the conversion and the selectivity obtained from the membrane reactor were superior to those of the conventional fixed-bed reactor. It was shown by the theoretical study that the assumptions of isothermal and plug-flow conditions overestimated the performance of the reactors. The membrane reactor with a catalyst packed in the shell side showed superior performance to the one with a catalyst packed in the tube side because the former had lower heat transfer resistance than the latter. The operating modes in the separation side played an important role in determining the reactor performance. The use of reactive sweep gas did not only rapidly consume the permeating H2 but also supplied additional heat to the reaction side; however, the resulting performance may be interior to the other operating modes such as vacuum and inert sweep gas modes.View full abstractDownload PDF (937K)
Materials and Devices
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Hiroshi Sato, Takeshi Ohtsu, Isao KomasawaArticle type: Research Papers
Subject area: Materials and Devices
2002 Volume 35 Issue 3 Pages 255-262
Published: 2002
Released on J-STAGE: June 26, 2002
JOURNAL RESTRICTED ACCESSThe preparation of ultrafine Pd and Pd-Au particles, in AOT (sodium bis(2-ethylhexyl) sulfosuccinate), CTAC (cetyltrimethylammonium chloride) and C18E7 (polyoxyethylene (7) oleyl ether) reverse micelles, using KBH4 as a reducing agent, has been studied. Excess KBH4 is required, because part of this is lost by hydrolysis and also by reduction of the surfactants. The particles in reverse micellar solution exhibit an activity for the hydrogenation of both water-soluble allyl alcohol and water-insoluble styrene, but the activity is inhibited by the surfactant molecules. Immobilization of the particles on solid supports, derivatized with a thiol-terminated silane, was carried out, aiming at possible applications as supported catalysts. The supported catalysts also exhibit hydrogenation activity, when the surfactant molecules are removed from the surface of the catalysts by calcination.View full abstractDownload PDF (444K)
Separations
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Zafer Karagölge, Mahir Alkan, Bünyamin DönmezArticle type: Research Papers
Subject area: Separations
2002 Volume 35 Issue 3 Pages 217-225
Published: 2002
Released on J-STAGE: June 26, 2002
JOURNAL RESTRICTED ACCESSThe removal of arsenic from colemanite ore containing arsenic by the froth flotation was studied. Flotation experiments were carried out in two stages. First, the effects of flotation time, the gas flow rate, particle size, the solid-to-liquid ratio and temperature without adding any conditioning reactivities were investigated. Later, the effects of the kinds and concentrations of the collector, frother and control reagents, and their combinations were examined. By using the most convenient parameter values, it was found that the recovery percentage of the ore and the removal percentage of arsenic can reach 75.50% and 90.31%, respectively.View full abstractDownload PDF (425K) -
Eiji Iritani, Yasuhito Mukai, Yukihiko ToyodaArticle type: Research Papers
Subject area: Separations
2002 Volume 35 Issue 3 Pages 226-233
Published: 2002
Released on J-STAGE: June 26, 2002
JOURNAL RESTRICTED ACCESSIn order to experimentally examine the influence of the electrostatic interactions of charged particles on the properties of a filter cake that accumulates on microfiltration membranes, microfiltration experiments are conducted using binary particulate mixtures of titanium dioxide and silicon dioxide having the different values of the isoelectric point for each material. Electrostatic forces affect the average porosity and the average specific filtration resistance of the filter cake formed during filtration. In the pH range where two particles have opposite electrical charges, the particles tend to aggregate, and the cake formed is loosely packed, resulting in a lower resistance to flow. In contrast, in the pH range where both particles are charged with the same sign, particles are well dispersed by repulsive electrostatic forces, and form compact cakes of higher resistance during filtration, leading to lower filtration rates. Moreover, it is found that such charge effects of particles are weakened in the presence of salts because the double-layer thickness is suppressed. An important result is that surface interactions (hence the suspension stability) are as important as operating conditions for microfiltration processing of binary particulate mixtures.View full abstractDownload PDF (560K) -
Maiko Yamanobe, Hiroshi Takiyama, Masakuni MatsuokaArticle type: Research Papers
Subject area: Separations
2002 Volume 35 Issue 3 Pages 247-254
Published: 2002
Released on J-STAGE: June 26, 2002
JOURNAL RESTRICTED ACCESSSolid-state polymorphic transformation of bisphenol A (BPA) and DL-methionine (DL-Met) crystals was carried out experimentally with XRD and DSC. The kinetics and the governing steps of transformation were discussed on the basis of a model proposed previously by the authors. For BPA, the transformation was found to be controlled by nucleation and growth of the stable polymorph in the early period followed by the growth step after sufficient nucleation had occurred, while the transformation of DL-Met was solely controlled by the growth step. The difference in the governing steps between BPA and DL-Met was attributed to the numbers of nuclei of the stable phase present in the initial crystals. This was supported by additional experiments with mechanically stressed BPA crystals in which the governing step of the transformation was changed to be growth-limited. These results showed the validity of the proposed model of solid-state transformation to describe different types of transformation behaviors.View full abstractDownload PDF (4231K)
Process Systems Engineering
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Chyi-Tsong Chen, Far-Yi LeeArticle type: Research Papers
Subject area: Process Systems Engineering
2002 Volume 35 Issue 3 Pages 274-284
Published: 2002
Released on J-STAGE: June 26, 2002
JOURNAL RESTRICTED ACCESSThis paper presents a learning control strategy for nonlinear process systems having inverse response. Implemented in a generalized Smith predictor configuration, the proposed control scheme integrates a learning-type nonlinear controller and a statically equivalent, minimum-phase predictor. The incorporated minimum-phase predictor is used to compensate an undesired inverse response behavior, which therefore enables the nonlinear controller to learn to control the nonlinear, non-minimum phase processes adaptively by simply using an output-error based learning algorithm. The effectiveness and applicability of the proposed scheme are demonstrated through controlling a nonlinear Van de Vusse reactor in the presence of inverse response characteristics. Performance comparison of the proposed scheme with a previously reported nonlinear technique is performed extensively in this work. The simulation results show that the proposed learning control strategy appears to be an effective and promising approach to the direct control of non-minimum phase nonlinear processes.View full abstractDownload PDF (538K)
Biochemical, Food and Medical Engineering
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Kazuo Kondo, Michiaki Matsumoto, Akane Kojo, Ryosuke MaedaArticle type: Research Papers
Subject area: Biochemical, Food and Medical Engineering
2002 Volume 35 Issue 3 Pages 241-246
Published: 2002
Released on J-STAGE: June 26, 2002
JOURNAL RESTRICTED ACCESSChitinase from the extract of pupae of Pieris rapae crucivora Boisduval was purified through the successive steps of CM-Sephadex C-50 ion exchange chromatography and gel filtration chromatography with Sephadex G-150 from crude enzyme extract. Then the active fractions named Chi-A and Chi-B were obtained. The purity of the enzyme increased up to 12.4- and 2.17-fold and the recovery of the enzyme activity were 42.4 and 4.58%, for the fraction Chi-A and Chi-B, respectively. The homogeneity and molecular weight of isolated Chi-A were evaluated by SDS-PAGE. The homogeneity of Chi-A was confirmed as a single band on SDS-PAGE and the molecular weight was estimated to be 48, 000. The purified Chi-A had an optimal pH of 5.0 for the hydrolysis reaction when glycol chitin was used as a substrate. Chi-A was stable in the pH range of 4.0–8.0 and retained its 70% activity at 310 K. The chitinase from pupae of Pieris rapae crucivora Boisduval exhibited typical Michaelis-Menten type kinetics. The kinetic parameters for the hydrolysis reaction with glycol chitin by Chi-A were determined to be 1.43 × 10–2 kg/(m3·h) as Vmax and 23.9 kg/m3 as Km at 310 K. We also found that Chi-A revealed a chitin synthase activity. A large amount of N-acetylchitopentaose was efficiently formed by the transglycosylation from N-acetylglucosamine with Chi-A.View full abstractDownload PDF (418K) -
Yoshiyuki Koizumi, Jumpei Nishi, Masahito TayaArticle type: Short Communications
Subject area: Biochemical, Food and Medical Engineering
2002 Volume 35 Issue 3 Pages 299-303
Published: 2002
Released on J-STAGE: June 26, 2002
JOURNAL RESTRICTED ACCESSThe photosterilization of Escherichia coli cells using iron-doped TiO2 (Fe/TO) particles was investigated under the conditions of initial cell concentration of 1 × 1011 cells/m3, incident light intensity of 14 W/m2 and Fe/TO concentration of 0.01 kg/m3. Among the Fe/TO particles prepared by changing the Fe weight fraction (WFe/TO = 0–3.0 wt%) and calcination temperature (Tc =473–1073 K), it was found that the highest sterilization rate was achieved at a dissolved oxygen (DO) concentration of 0.54 ppm when using the Fe/TO particles prepared at WFe/TO = 1.8 wt% and Tc = 773 K. In the photosterilization using the selected Fe/TO particles under various DO concentrations of 0.54–7.9 ppm, the sterilization rate of the cells increased with increasing DO concentration up to 2.0 ppm and the rate was nearly constant above this DO concentration. At lower DO concentrations of 0.54–2.0 ppm, furthermore, the rate constant in the photosterilization with the Fe/TO particles was 1.5–13 times higher over the virgin TiO2 without iron doping.View full abstractDownload PDF (1235K)
Safety, Environment and Energy
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Akihiro Takeuchi, Shinichi Kato, Takayuki Watanabe, Yoshimasa AkatsukaArticle type: Research Papers
Subject area: Safety, Environment and Energy
2002 Volume 35 Issue 3 Pages 234-240
Published: 2002
Released on J-STAGE: June 26, 2002
JOURNAL RESTRICTED ACCESSCarbon halides, especially halons (bromofluorocarbons), are compounds known to deplete the ozone layer and contribute to global warming. Appropriate treatments to decompose halon waste is important to protect the environment. A dry process to decompose halon has been developed. Solid alkaline carbonate and hydrate obtained from dolomite were prepared for the reactants to decompose halon and to react with the fluorine and bromine produced by the halon decomposition. Twelve kinds of reactants were obtained by changing the burning temperature and burning time. The amount of the decomposed halon and the conversion were correlated with the pore distributions in the reactants. The distributions of F and Br differed depending on the preparation of the reactants. The difference would be attributed to the reactivity and the diffusion rate of the gases produced by the decomposing halon.View full abstractDownload PDF (4470K) -
Jea-Keun Lee, Keyoung-Ran Lee, Sung-Ho Hong, Kyoung-Hee Kim, Byung-Hun ...Article type: Research Papers
Subject area: Safety, Environment and Energy
2002 Volume 35 Issue 3 Pages 285-289
Published: 2002
Released on J-STAGE: June 26, 2002
JOURNAL RESTRICTED ACCESSExperiments on the electrochemical oxidation of ammonia in artificial seawater are carried out in a lab-scale electrochemical apparatus. The operating parameters are current density (16–66 A/m2) and hydraulic residence time in a reactor (30–90 sec). The ammonia concentration in the effluent of the reactor exponentially decreases with increasing the current density and the hydraulic residence time, while the concentration of chlorine residuals increases. Most of the chlorine residuals are free available chlorine and the remainder is dichloramine. A strong disinfection characteristic can be seen during electrochemical treatment of ammonia.View full abstractDownload PDF (364K) -
Erwin P. Ona, Xuemei Zhang, Shoji Ozawa, Hitoki Matsuda, Hiroyuki Kaki ...Article type: Research Papers
Subject area: Safety, Environment and Energy
2002 Volume 35 Issue 3 Pages 290-298
Published: 2002
Released on J-STAGE: June 26, 2002
JOURNAL RESTRICTED ACCESSThe present paper investigates the effectiveness of ultrasound for promoting solidification as well as relaxing the supercooling of erythritol, as a phase change material, in a lab-scale heat storage unit. Temperature distributions along the axial and radial directions of the heat exchange pipe during the heat release experiments were measured to evaluate ultrasonic irradiation effect on the promotion of solidification. Simultaneously, the solidification behavior of erythritol around the heat exchange pipe was examined to study the mechanism of supercooling relaxation elaborately.
The obtained experimental results with a non-ultrasonic irradiation condition indicated that there was a large temperature difference in the melt accompanied by supercooling for several tens of degrees. As verified by both DSC and XRD analyses, it was found that two types of solid phases of erythritol might be formed depending on crystallization conditions. On the other hand, a more uniform temperature profile within the melt was observed when ultrasound was irradiated. It was found that ultrasonic irradiation prevented supercooling by such appropriate features as characterized by acoustic streaming and the propagation of sound pressure, etc. It was considered that ultrasonic irradiation might be used as a method to initiate the nucleation process and promote dispersion of crystals throughout the melt, resulting in the suppression of supercooling.View full abstractDownload PDF (11406K)
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