All issues
Volume 33 (2007)
- Issue 6 Pages 501-
- Issue 5 Pages 383-
- Issue 4 Pages 279-
- Issue 3 Pages 187-
- Issue 2 Pages 77-
- Issue 1 Pages 1-
Predecessor
Volume 33, Issue 3
Displaying 1-14 of 14 articles from this issue
- |<
- <
- 1
- >
- >|
Physical Properties and Physical Chemistry
-
Ryo Hayasaka, Masayuki Aoshima, Akira Satoh, Tamotsu Majima2007 Volume 33 Issue 3 Pages 187-194
Published: 2007
Released on J-STAGE: June 25, 2007
JOURNAL RESTRICTED ACCESSWe have studied the influences of magnetic field, shear rate, and random forces on transport coefficients such as viscosity and diffusion coefficient, and also on the orientational distributions of hematite particles in a dilute colloidal dispersion. Hematite particles were modeled as spheroids with a magnetic moment normal to the particle axis, and they were assumed to perform rotational Brownian motion in a simple shear flow as well as an external magnetic field. The basic equation of the orientational distribution function was derived from the balance of the torques and solved by numerical analysis. The results obtained are summarized as follows. In a very strong magnetic field, the motion of the rod-like particles is restricted to the plane normal to the shearing plane because the magnetic moment of the particles is restricted to the magnetic field direction. In a relatively strong magnetic field, the rod-like particles can rotate freely around the magnetic field direction in the case of a small shear rate, whereas they tend to incline in the shear flow direction with the magnetic moment pointing in the magnetic field direction in the case of a large shear rate. Large values of the diffusion coefficient cannot be obtained in this case, since the orientational distribution is governed by two typical motions of the particles: firstly, particles move in the direction of the sedimentation with the particle axis coinciding with the direction of the sedimentation; and secondly, particles move with the axis normal to the sedimentation direction.View full abstractDownload PDF (2471K)
Transport Phenomena and Fluid Engineering
-
Yoshihito Kato, Yutaka Tada, Hiroko Sato, Hiromu Harada, Yuichiro Naga ...2007 Volume 33 Issue 3 Pages 195-200
Published: 2007
Released on J-STAGE: June 25, 2007
JOURNAL RESTRICTED ACCESSA new type of mixer, OCTAGIT, which can mix liquid with viscosity of up to several Pa·s and generate an unsteady flow with small power consumption, has been developed by Nomura Micro Science Co. Ltd.. This mixer has a double disc type impeller which is operated by double shafts. OCTAGIT generated many vortex rings to provide good liquid mixing over a wide range of viscosity. To evaluate the performance of OCTAGIT, the mixing time, profile of circulating time and power consumption were measured. In the turbulent region, OCTAGIT has a circulating time profile with only one peak of frequency, and the mixing time is shorter than that of a disc turbine operating under the same power consumption per unit volume.View full abstractDownload PDF (1426K) -
Takako Shiba, Yushi Hirata, Yoshiro Inoue2007 Volume 33 Issue 3 Pages 201-207
Published: 2007
Released on J-STAGE: June 25, 2007
JOURNAL RESTRICTED ACCESSA new method of multifractal analysis to evaluate the fluid mixing pattern of three kinds of fluid components is proposed. The geometrical characteristics of mixing pattern are expressed on a spectral surface of quasi-local fractal dimension vector q, whose dimension agrees with the number of fluid components, and quasi-global fractal dimension f(q). In ordinary multifractal analysis, local and grabal fractal dimensions are related with an escort probability measure P (β), which is a function of single scan parameter β. In the present analysis, the scan parameter vector β whose dimension is the same as q is newly introduced. The multifractal variables are calculated by scanning independently each component of β. In the analysis of mixing pattern of many fluids, it is important to select the fluid components and subregion (or support) that contains the fluid in question. Depending on the combination of fluid and support, many different multifractal spectra are obtained. Complex intermixing between two or more fluid components can be analyzed quantitatively with these spectra.View full abstractDownload PDF (1094K) -
Hiroyuki Kawasaki, Tatsumi Yamamoto2007 Volume 33 Issue 3 Pages 208-210
Published: 2007
Released on J-STAGE: June 25, 2007
JOURNAL RESTRICTED ACCESSExperiments were performed to study the effects of multiple draft tubes with perforated plates on average gas holdup, φ, volumetric mass transfer coefficient, kLa, and liquid mixing time, tM, in a bubble column with 5 draft tubes, and a varying number of holes, n, of constant diameter on the perforated plates.
φ and kLa increased with increasing superficial gas velocity, uG0, and n, respectively. The highest values were obtained for 5 draft tubes with perforated plates having n=323. tM decreased with increasing uG0. For the perforated plates with n=21, tM increased with increasing N at the same uG0; but with n=323, tM was independent of N and became equal to one with no draft tube.View full abstractDownload PDF (242K)
Separation Engineering
-
Naotsugu Itoh, Tomomitsu Akiha, Takafumi Sato2007 Volume 33 Issue 3 Pages 211-217
Published: 2007
Released on J-STAGE: June 25, 2007
JOURNAL RESTRICTED ACCESSThe formation process of thin palladium on a porous alumina tube by MOCVD using palladium diacetate as the metal organic salt source was clarified and optimized. It was found that a palladium composite membrane with fewer defects could be prepared by keeping the sublimation temperature at 200°C, the decomposition temperature at 220°C, and the chamber pressure at 170 Pa during the MOCVD process. By CFD calculations, measurements of change in the electro—resistance and air leak tests along the palladium—deposited tube, it was shown that the plugging of pores in the support tube due to palladium deposition progressed from the base to the tip. The membrane prepared had a hydrogen permeability of 4.42×10−9 mol·m−1·s−1·Pa−0.5 and a H2/N2 ideal separation factor of 11500 at 300°C.View full abstractDownload PDF (1151K) -
Yosuke Matsukuma, Hidemasa Kakigami, Gen Inoue, Masaki Minemoto, Akino ...2007 Volume 33 Issue 3 Pages 218-226
Published: 2007
Released on J-STAGE: June 25, 2007
JOURNAL RESTRICTED ACCESSAn optimization method for numerical simulation of CO2 adsorption systems was studied. The optimization target is an adsorption system of CO2 contained in exhaust gas from a power plant by use of rotor towers filled with honeycomb type zeolite. The fully optimized conditions were obtained by sequentially repeating optimization for nine parameters until all parameters reached steady states. The optimal operation conditions for the actual plant (flow rate of exhaust gas: 70000 m3(STP)·h−1) were obtained from our simulations. As a typical example, the following optimal operation conditions were obtained for a boundary CO2 recovery rate of more than 60%, CO2 concentration of more than 90% and minimum power consumption energy. (1) The power consumption energy including blower energy was 899 KJ. (2) CO2 recovery rate was 60.1%. (3) CO2 concentration was 92.4%. It was also found that the power consumption energy can be reduced further if the system is slightly changed or the target recovery rate and the concentration are slightly decreased.View full abstractDownload PDF (715K)
Biochemical, Food and Medical Engineering
-
Osamu Harada, Minoru Kuwata, Tohei Yamamoto2007 Volume 33 Issue 3 Pages 227-231
Published: 2007
Released on J-STAGE: June 25, 2007
JOURNAL RESTRICTED ACCESSWe developed equipment to allow continuous treatment of collagen slurry under hydrothermal condition. Using this equipment, we were able to increase the amount of gelatin obtained from calf skin using only water in a reaction time of under 2 seconds at 260°C. The molecular weight distribution of the gelatin can be varied by adjusting the reaction temperature and adding a small amount of a catalyst such as acetic acid. This adjustability is advantageous in the utilization of the gelatin. The gelatin is easily purified, allowing hydrolysis of the collagen in water alone. Therefore this processing technology greatly simplifies the manufacture of gelatin compared with the conventional method.View full abstractDownload PDF (829K)
Micro and Nano Systems
-
Noriyuki Yoshio, Yushi Hirata, Yoshiro Inoue2007 Volume 33 Issue 3 Pages 232-238
Published: 2007
Released on J-STAGE: June 25, 2007
JOURNAL RESTRICTED ACCESSIn microreactor systems, concentration distribution is deformed by secondary flow when a fluid passes a join, bend, or bifurcation section in a microchannel. If flow is laminar and steady, a mapping matrix can be defined and it transforms an inlet concentration vector to an outlet one. This transform matrix can be constructed of only the flow velocity information. However, it is generally difficult to find the transform matrix that satisfies rigorously the mass conservation condition. To overcome this difficulty, a new algorithm has been developed. In the procedure, a diffusion equation for the deviation from conservative law is utilized to relax the local errors. To evaluate the present algorithm, the outlet concentrations in the channel joining sequentially with five branches were calculated and the results were compared with the experimental ones.View full abstractDownload PDF (886K)
Materials Engineering and Interfacial Phenomena
-
Yanlin Zhang, Takahiko Ban, Akihisa Shioi2007 Volume 33 Issue 3 Pages 239-245
Published: 2007
Released on J-STAGE: June 25, 2007
JOURNAL RESTRICTED ACCESSOn the basis of the nonlinear reaction-diffusion kinetics, spontaneous formation of physical/chemical microstructure can be introduced into fine particles formed in a homogeneous hydrogel. In this paper, we discussed the structure and chemical distribution within the particles formed by the diffusion of Ba2+ and Sr2+ ions and SO42− ions in opposite directions in agar gel and agar/gelatin mixed gel. In agar gel, the structure of a particle depends strongly on its position in the gel, i.e., structures with extensive diversity are obtained. This is the same trend as that found in the single-component gel of gelatin. In mixed gel, however, the particles are formed only in a narrow range of the gel, and hence the structure of the particle does not exhibit such diversity. This result may give fundamental information applicable to the design of a reaction-diffusion system for the particle formation; how particles with different structures are formed at different positions in a gel or how such diversity of particle structures can be avoided.View full abstractDownload PDF (1792K)
Energy
-
Effect of Catalysis on Tar Elimination and Gas Production from Fluidized Bed Gasification of BiomassTsuyoshi Teramae2007 Volume 33 Issue 3 Pages 246-256
Published: 2007
Released on J-STAGE: June 25, 2007
JOURNAL RESTRICTED ACCESSExperiments of biomass gasification using bench-scale fluidized bed gasifier at 873 K in N2 and steam were carried out to investigate the effect of catalysts on tar emission abatement and gas composition. At first activated alumina particles and sand were used as bed materials to compare the amounts of tar emission and generated gas compositions. Activated alumina particles were shown to greatly reduce tar emission, which decreased as the ratio of feed rate of activated particles and biomass increased. In gasification tests using eight kinds of non-metallic catalysts including the activated alumina particles, no differences between the catalysts in the amount of generated gas were found in N2. On the other hand, in steam gasification as tar emission decreased the amount of generated gas increased due to a catalystic action between tar and steam. It was found that the amount of tar emission and generated gas correlated with the amount of acid sites on the catalysts.View full abstractDownload PDF (825K) -
Hayato Nakajima, Yoshiyuki Imai, Seiji Kasahara, Shinji Kubo, Kaoru On ...2007 Volume 33 Issue 3 Pages 257-260
Published: 2007
Released on J-STAGE: June 25, 2007
JOURNAL RESTRICTED ACCESSEffect of sulfur dioxide partial pressure on the reaction of iodine, sulfur dioxide and water, which is a unit reaction in the IS process for thermochemical hydrogen production, was studied experimentally at 323 K under iodine saturation. Quasi-equilibrium state was observed in the presence of sulfur dioxide gas at constant pressure. The composition of the poly-hydriodic acid solution formed was discussed assuming an ideal desulfurization by the reverse reaction of the Bunsen reaction. The value of HI/(HI+H2O) of the desulfurized solution was large at high sulfur dioxide pressure and reached the maximum of 15.7±0.3 mol%.View full abstractDownload PDF (325K)
Environment
-
Shingo Ando, Naoki Tanahashi, Naoto Mihara, Takafumi Fujita, Chouyuu W ...2007 Volume 33 Issue 3 Pages 261-266
Published: 2007
Released on J-STAGE: June 25, 2007
JOURNAL RESTRICTED ACCESSThe decomposition of trichloroethylene (TCE) and Cl sorption by alkaline sorbent were investigated in a reactor filled with CaO or Na2CO3 fine particles.
Under a TCE-N2 atmosphere without CaO and Na2CO3, it was found that HCl, C2Cl4 and CCl4 were generated by the thermal decomposition of TCE at temperatures above 873 K. Similarly, under the TCE-H2O-N2 atmosphere without CaO and Na2CO3, HCl was generated at temperatures above 673 K, and the presence of CaO or Na2CO3 sorbent was found to promote the decomposition of TCE in the temperature range of 473–1073 K. Under the TCE-N2 atmosphere in the presence of CaO and Na2CO3 sorbents, HCl and C2Cl2 were generated by the decomposition of TCE; and under the TCE-H2O-N2 atmosphere, TCE was decomposed to HCl and C2H2Cl2. During TCE decomposition, the formation of CaCl2 and NaCl was observed, and hence it was concluded that Cl gaseous compounds formed by the decomposition of TCE were absorbed on CaO and Na2CO3.
As for the Cl sorption on alkaline sorbents, the highest conversion values of CaO to CaCl2 of 0.60 and Na2CO3 to NaCl of 0.53 were obtained at a temperature of 873 K under the TCE-N2 atmosphere. Under the TCE-H2O-N2 atmosphere, the conversion of CaO to CaCl2 was higher than that without H2O in the temperature range of 473–873 K. However, at a temperature of 1073 K, the conversion of CaO to CaCl2 decreased. On the other hand, conversion of Na2CO3 to NaCl was higher in the temperature range of 473–1073 K in the presence of H2O than under the TCE-N2 atmosphere. Under the TCE-H2O-N2 atmosphere, the highest conversion values of CaO to CaCl2 of 0.72 and Na2CO3 to NaCl of 0.66 were obtained at a temperature of 873 K.View full abstractDownload PDF (432K) -
Ryuta Hidaka, Masahiro Yoshida, Yasuo Hatate, Yoshihiro Kouhara2007 Volume 33 Issue 3 Pages 267-272
Published: 2007
Released on J-STAGE: June 25, 2007
JOURNAL RESTRICTED ACCESSSealing glasses are necessary materials for the sealing process in electronic applications. Our goal is to develop lead-free glasses with a low melting temperature (less than 600°C) and good chemical durability for sealing. In this study, Li2B4O7, ZnO, KPO3, Nb2O5, and Al2O3 were used to prepare lead-free glasses. Glass transition temperature, softening temperature, thermal expansion coefficient, and water resistance were measured in detail in ternary (Li2B4O7–ZnO–KPO3) and quaternary (Li2B4O7–ZnO–KPO3–Nb2O5 or Li2B4O7–ZnO–KPO3–Al2O3) systems. The lead-free glass with 24 wt% Li2B4O7–6 wt% ZnO–70 wt% KPO3 had a high sealing property (sealing temperature: 450°C), an amorphous structure, and a low melting point. However, it had a low water resistance (weight loss: 30%) and a high thermal expansion coefficient (14.5×10−6/K). On the other hand, 21.6 wt% Li2B4O7–5.4 wt% ZnO–63 wt% KPO3–10 wt% Nb2O5 glass had a high water resistance (weight loss: 1.6%), a low thermal expansion coefficient (12.7×10−6/K), a high sealing property (sealing temperature: 480°C), an amorphous structure, and a low glass transition temperature. The prepared lead-free glass exhibited a high performance as a substitute for the commercially available lead glass.View full abstractDownload PDF (1131K) -
Junji Shibata, Norihiro Murayama, Shinsuke Nakajima2007 Volume 33 Issue 3 Pages 273-277
Published: 2007
Released on J-STAGE: June 25, 2007
JOURNAL RESTRICTED ACCESSFour Mg/Al type hydrotalcite-like materials (HT) with different interlayer anions were synthesized by a co-precipitation method under the condition of Mg/Al=2.5, and their pH buffer action was investigated. Slurries of these HTs each showed a constant pH due to the buffer action, with equilibrium pHs in the following order: Mg–Al–SO42−HT (pH 9.0)>Mg–Al–CO32−HT (pH 8.5)>Mg–Al–NO3−HT (pH 8.0)>Mg–Al–Cl−HT (pH 7.6). The equilibrium pHs of Mg–Al–SO42−HT and Mg–Al–CO32−HT, in which divalent anions are intercalated as exchangeable anions, are higher than those of Mg–Al–Cl−HT and Mg–Al–NO3−HT, which have monovalent anions in the HT structure. This phenomenon is mainly caused by the consumption of H+ in aqueous solution with SO42− or CO32− released from HT. The slightly higher equilibrium pH of Mg–Al–NO3−HT compared with Mg–Al–Cl−HT is thought to be based on the difference in the amount of OH− in the HT interlayer. From these results, it is clear that the pH buffer action of the layered double hydroxide varies with the kind and amount of anion captured in HT.View full abstractDownload PDF (317K)
- |<
- <
- 1
- >
- >|