KAGAKU KOGAKU RONBUNSHU
Online ISSN : 1349-9203
Print ISSN : 0386-216X
ISSN-L : 0386-216X
Volume 28 , Issue 6
Showing 1-20 articles out of 20 articles from the selected issue
Special Issue[Peripheral Technologies Toward Green Energy System]
  • Mo Yun, Jun Fukai, Yoshio Morozumi, Osamu Miyatake, Keiji Kurokawa
    2002 Volume 28 Issue 6 Pages 661-665
    Published: November 20, 2002
    Released: May 30, 2009
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    The combustion gas temperatures in the free board of an internal fluidized-bed furnace using livestock wastes as fuel are experimentally and numerically investigated. Broiler excrements and mixtures of broiler-swine excrements are provided as the fuel. The gas temperatures in the free board are measured at several locations. The exhaust gas temperature is found to be above 1,000 K even for the mixed fuels whose moisture content is 40 wt%.
    Three-dimensional combustion simulations based on k-ε techniques are performed in the free board. The calculated gas temperatures in the free board reasonably agree with the experimental ones. The calculations show that the fuel gases are completely burned, maintaining the free board at high temperatures.
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  • Keiichi Tomishige, Mohammad Asadullah, Shin-Ichi Ito, Kimio Kunimori
    2002 Volume 28 Issue 6 Pages 666-672
    Published: November 20, 2002
    Released: May 30, 2009
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    Conventional methods of biomass gasification to hydrogen and synthesis gas are carried out at high temperature. The purpose of this study is to develop a novel catalytic process for biomass gasification at low temperature (773–873 K) with high energy efficiency. A cellulose was used as the model compound of biomass, and the performance of our catalysts was compared with those of dolomite and non -catalyst in batch and continuous-feeding fluidized bed reactor. In reaction tests with various catalysts, Rh/CeO2 exhibited higher performance than other catalysts, but its deactivation was also observed during the reaction, caused by the sintering of the CeO2 support. A commercial steam-reforming catalyst also showed high activity, but its deactivation due to carbon deposition was observed. We also prepared Rh/CeO2/SiO2, which gave higher C-conversion to gas and was more stable than Rh/CeO2. In comparison with conventional methods (dolomite, non-catalyst, Ni catalyst), it was found that the gasification using Rh/CeO2/SiO2 catalyst can give a higher yield of synthesis gas at much lower temperature and with higher stability.
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  • Yohsuke Matsushita, Akinori Goto, Masakazu Shoji, Tsuyoshi Yamamoto, H ...
    2002 Volume 28 Issue 6 Pages 673-679
    Published: November 20, 2002
    Released: May 30, 2009
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    A new type combustor with a turntable at the bottom was proposed in order to deal effectively and cleanly with wood-chips produced by the construction industry. The turntable made it possible to clean up combustion residue and ash during combustion and to operate the combustor continuously. First, the optimum air ratio for the combustor was experimentally determined. Under this condition, two-phase (solid and gas) combustion was then analyzed numerically and the results were compared with experimental ones in order to examine the validity of the mathematical model. The calculated results were in good agreement with the experimental ones in terms of temperature and O2 and CO2 concentration distributions in the combustor, thus demonstrating the validity of the mathematical model. Both sets of results revealed low O2 concentration and high CO concentration in the middle part of the combustor over the solid phase, and though this phenomenon is thought to cause high CO emission, a favorable mixture of uncombnsted gas and air was achieved in the middle and top part of the combustor. The new type of combustor developed in this study was thus found to be effective.
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  • Mitsuru Yaga, Kazutaka Suzuki, Hajime Endo, Tsuyoshi Yamamoto, Hideyuk ...
    2002 Volume 28 Issue 6 Pages 680-685
    Published: November 20, 2002
    Released: May 30, 2009
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    Efforts to apply Large Eddy Simulation (LES), which is superior to the k-ε 2 equation models to predicting turbulent flow in turbulent diffusion Flames have been made in recent years as the processing capacity of computer have been improved. Use of the dynamic SGS model to dynamically calculate the constant appearing in LES is expected to yield greater universality. In this study, we analtzed the methane-air turbulent diffusion flame in a combustor by LES with the Dynamic SGS model and examined the validity of this calculation method. The calculated temperature and CH4 mole fraction distribution were in fairly good agreement with the experimental results; the calculated CO mole fraction distribution did not agree well with the measured result, because a simple CO reaction mechanism. In future, to develop a combustion model suitable for LES including a combustion reaction scheme.
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  • Masataka Arai, Taro Shinkawa, Masahiro Saito
    2002 Volume 28 Issue 6 Pages 686-692
    Published: November 20, 2002
    Released: May 30, 2009
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    This paper focuses on the promotion of internal exhaust gas recirculation (EGR) in a swirl-type combustor by using a flame holder with a triangle-roof-shaped fin. The effect of the flame holder was examined by comparison of combustion characteristics such as NOx destruction and gas temperature with those in the absence of the flame holder. When the flame holder was used, the flame spread widely and uniformly within the combustor and the flame length became about half of that not used, since the flame holder was effective to promote internal EGR and the mixing of fuel and combustion gas. Exhaust gas of high temperature and low-oxygen concentration was found to recirculate in the main combustion zone, the internal EGR was effective to reduce NOx emission from the combustion system without temperature reduction of the combustion gas.
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  • Masakazu Shoji, Tsuyoshi Yamamoto, Shoji Tanno, Hideyuki Aoki, Takatos ...
    2002 Volume 28 Issue 6 Pages 693-698
    Published: November 20, 2002
    Released: May 30, 2009
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    To investigate the mechanism of fuel NO formation, an experimental study using a flow reactor and a numerical simulation with a detailed kinetic model were performed. Pyridine was used as a model compound of fuel nitrogen, and the effects of oxygen and H2O concentrations on reaction mechanism was investigated. The results showed that oxygen concentration had little effect on the reaction mechanism, while NO formation was inhibited with an increase in H2O concentration. In this reaction mechanism, NO is mainly formed by the NCO+O reaction, which is an important reaction for NO formation. At high H2O concentration, many 0 radicals are consumed by the O+H2O reaction. Therefore, the formation of NO is reduced with an increase in H2O concentration.
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  • Ning Zhu, Seizo Kato, Yong Jiang
    2002 Volume 28 Issue 6 Pages 699-704
    Published: November 20, 2002
    Released: May 30, 2009
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    Ultrasonic CT has been applied to thermal environmental measurements as a nonintrusive method. This research tries to develop a new ultrasonic CT reconstruction method to deal with the problem of insufficient projection data due to limited projection angle. The new CT reconstruction algorithm is based on inverse matrix transformation, which differs from the conventional CT reconstruction, known as FBP (Filtered Back Projection) with SL Filter. The current paper, describes three iterative CT reconstruction algorithms. Computer simulations were conducted to verify these algorithms, and the reconstruction results were compared. An experiment on 3D temperature distribution measurement was carried out to validate the proposed algorithms. From the simulation and experimental results, normalized CGM (Conjugate Gradient Method), which takes account of regularized least squares, was suggested to be the optimum iterative method for CT reconstruction under the condition of limited projection angle.
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  • Masataka Kubo, Masahisa Shinoda, Tomohiko Furuhata, Kuniyuki Kitagawa
    2002 Volume 28 Issue 6 Pages 705-712
    Published: November 20, 2002
    Released: May 30, 2009
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    We attempted to improve the power generation performance of a thermoelectric device by making rectangular incisions in it to increase the temperature difference between the hot and cold ends of the device, while keeping the electrical resistance low. By means of experimental measurements and numerical simulations, dependences of the temperature difference between both ends, the generated electric power and the conversion efficiency of the device on the hot-end temperatures and the incision sizes were examined. The numerical results were in good agreement with the experimental ones, and the validity of the calculations was confirmed. The numerical analyses revealed that the increase of the horizontal, rather than the vertical, size of the incision was effective in increasing the temperature difference between both ends. Furthermore, optimized incision sizes were obtained for each hot-end temperature. The generated electric power was maximized to 41.4 mW by the device with the optimized incision sizes, and improved by 39.9% in comparison with that without incisions. On the other hand, the conversion efficiency was maximized to 0.82% and improved by 39.0%.
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  • Nobuhiro Maruoka, Makoto Asao, Tamotsu Miyako, Masatomo Nakamoto, Tomo ...
    2002 Volume 28 Issue 6 Pages 713-717
    Published: November 20, 2002
    Released: May 30, 2009
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    This paper describes the development of mesh-shaped PCM for the recovery of intermittentlyreleased, high-temperature heat from LD steelmaking converter and its systematic design for utilizing the recovered heat in the methanol production heat. Experiments were performed mainly to examine the effect of coating material and its film thickness on strength of the PCM. Copper, with a melting point of 1,356 K, was selected as the PCM. The results showed that the PCM coated doubly with Cr and Ni had enough strength in a heating test at 1,473 K. The heat and mass balances model showed the possibility that by using the developed PCM reactor, 25% of methanol required in Japan can be synthesized with only 25% of exergy consumption of conventional method.
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Themodynamics, Physical Properties and Molecular Simulation
  • Hiroshi Kuma, Qiusheng Liu, Kenji Nakamura, Fumio Takemura, Akira Yabe ...
    Type: Chemical Engineering Data
    Subject area: Themodynamics, Physical Properties and Molecular Simulation
    2002 Volume 28 Issue 6 Pages 759-767
    Published: November 20, 2002
    Released: May 30, 2009
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    This research aims to abtain fundamental data with which to develop chemical heat-pump systems utilizing the decomposition and synthesis reaction of methyl formate.
    Chemical equilibrium analysis of the decomposition and synthesis reaction of methyl formate under vapor-liquid equilibrium was applied to the flow system experimental data. The chemical equilibrium of the decomposition reaction was measured between 0.6 MPa and 1.5 MPa for the temperature range between 283 K and 343 K. The chemical equilibrium of the synthesis reaction was measured between 3.0 MPa and 5.0 MPa for the temperature range between 333 K and 393 K. By comparing the experimental values with the calculated values of chemical equilibrium under vapor-liquid equilibrium, it was found that the decomposition reaction reached equilibrium at about 343 K and the synthesis reaction reached equilibrium at about 393 K.
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Transport Phenomena, Fluid Mechanics and Mixing
  • Takefumi Nagata, Surat Areerat, Masahiro Ohshima, Masataka Tanigaki
    Type: Chemical Engineering Data
    Subject area: Transport Phenomena, Fluid Mechanics and Mixing
    2002 Volume 28 Issue 6 Pages 739-745
    Published: November 20, 2002
    Released: May 30, 2009
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    In polymeric foaming processes using CO2 as a physical foaming agent, polymer viscosity is one of key factors determining the cell size of the foams. The polymer viscosity is reduced when the foaming agent (CO2) gas is dissolved into the polymer. It is necessary to know a quantitative relationship between dissolved gas concentration and viscosity reduction, in order to control of cell size precisely and density in foaming processes. In this study, the relationship between shear viscosity of polypropylene and concentration of CO2 dissolved in the polymer was examined, by use of a capillary rheometer equipped at exit of extruder. The CO2-induced viscosity reduction can be predicted by employing the free volume theory and PVT equation of polymer-CO2 mixture. The estimations given by the developed model showed good agreement with the measured data.
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  • Hirosi Kunimatsu, Yoshiro Inoue, Yushi Hirata
    Type: Fundamental Research Paper
    Subject area: Transport Phenomena, Fluid Mechanics and Mixing
    2002 Volume 28 Issue 6 Pages 753-758
    Published: November 20, 2002
    Released: May 30, 2009
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    Hydrodynamic focusing of the inflow stream from the center channel was studied in a flow system in which the three microchannels converge into a single channel. This system is important as the elementary flow in microreactors in which micromixing is achieved by molecular diffusion without convective mixing. The width of the main stream from the center channel decreases along flow direction by the focusing effect. The dependence of the stream width on the confluence angle, the inlet velocity, and the fluid viscosity was examined both experimentally and by numerical simulation. By visualization of the contacting interface between two inlet fluids, the conditions under which the surface of the contacting interface is deformed after confluence were clarified.
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  • Akio Nakayama, Yoshihiro Takamiya
    Type: Fundamental Research Paper
    Subject area: Transport Phenomena, Fluid Mechanics and Mixing
    2002 Volume 28 Issue 6 Pages 772-775
    Published: November 20, 2002
    Released: May 30, 2009
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    The air-lift pump is presently being considered a method for recovering useful mineral resources from the deep-sea floor. However, with the present technology, its use is limited to a depth of 3,000 m. For recovery from greater depth, use of the electrolytic gas-lift pump can be considered, but design standerds for its use for this purpose have yet to be established. The aim of this study is to conduct a theoretical analysis of the water-pumping characteristics of the electrolytic gas-lift pump and to verify experimentally the usefulness of the analysis.
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Catalysis, Kinetics and Reactor Design
  • Masaru Hayashi, Yushi Hirata
    Type: Technical Research Paper
    Subject area: Catalysis, Kinetics and Reactor Design
    2002 Volume 28 Issue 6 Pages 733-738
    Published: November 20, 2002
    Released: May 30, 2009
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    The reaction field and rate-determining step of the transesterification of SLT-allylester allyl(5-chloro-2-oxo-1,3-benzothiazol-3(2H)-yl) acetate with methanol to form SLT-methylester in dichloromethane using potassium carbonate (K2CO3) as a catalyst were investigated. The reaction rate in solid -liquid phase was 45 times higher than that in homogeneous liquid phase, which indicates that the reaction takes place almost exclusively on the surface of K2CO3 particles and the reaction on the surface of K2CO3 is rate-determining step. In addition, by changing the order of supplying the reactants and catalyst into the reactor, it was found that the occurrence of an induction period for the reaction in the solid-liquid phase was caused by the combination of methanol with K2CO3.
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Particle Technology and Fluidization
  • Shinichi Ookawara, Kohei Ogawa
    Type: Letter to the Editor
    Subject area: Particle Technology and Fluidization
    2002 Volume 28 Issue 6 Pages 779-784
    Published: November 20, 2002
    Released: May 30, 2009
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    The relations between suspension viscosity and parameters of representative particle size distributions, viz., log-normal, Rosin-Rammler (RR) and Gaudin-Schuhmann (GS) distributions, were derived from a flow characteristics model for continuous multimodal suspension that was developed based on the model for discrete multimodal suspension (Ookawara and Ogawa, 2002). It was shown that, in the case of log-normal distribution, the viscosity exponentially increases with geometric standard deviation, σg. Since the viscosity is nearly constant in the σg range of below 1.1, the powder in this range can be regarded as monodisperse from the viewpoint of viscosity. It was also shown that, in both cases of RR and GS distributions, the viscosity rapidly decreases with index parameter n and approaches the viscosity of a unimodal suspension. This tendency is remarkable in the case of GS distribution because of its asymmetric characteristics.
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Biochemical, Food and Medical Engineering
  • Park Lianchun, Miki Funai, Masahiro Goto
    Type: Letter to the Editor
    Subject area: Biochemical, Food and Medical Engineering
    2002 Volume 28 Issue 6 Pages 776-778
    Published: November 20, 2002
    Released: May 30, 2009
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    A new mutation analysis system was developed by utilizing a DNA intercalator in reversed micelles. The hybridization signal was amplified by monitoring the intercalation behavior between a porphirine derivative and a double strand DNA in reversed micelles. Hybridization rate in reversed micelles was analyzed for three sample DNAs bearing a mutation in a different part. The location of the mutation significantly affected the hybridization behavior. This novel method allows the DNA concentration to be reduced to less than one-tenth of that employed in the conventional reversed micellar method.
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Safty, Enviroment and Energy
  • Michitaka Furubayashi, Syuji Hamano, Kenichi Nagai
    Type: Technical Research Paper
    Subject area: Safty, Enviroment and Energy
    2002 Volume 28 Issue 6 Pages 718-725
    Published: November 20, 2002
    Released: May 30, 2009
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    To study the regeneration of activated carbon used for removal of dioxins from flue gas, the behavior of adsorbates in activated carbon and the adsorptive capacity of the regenerated activated carbon were investigated by repeated exposure to flue gas and regeneration by thermal treatment in a nitrogen atmosphere.
    Adsorbed dioxins was decomposed in the activated carbon without desorption into the gas phase by the thermal treatment at 400° C under nitrogen. Dioxins did not accumulate in the activated carbon in the repeated regeneration tests. Chlorobenzen and chlorophenol showed similar behavior to dioxins. Sulfur also did not accumulate in the activated carbon, but mercury tended to accumulate slightly, and chlorine tended to accumulate remarkably. The adsorptive capacity of the activated carbon for dioxins and sulfur did not change during the repeated regeneration tests, but that for mercury and chlorine tended to decrease due to their accumulation in the activated carbon.
    The test results showed that the thermal treatment at 400°C under nitrogen was effective for regeneration of activated carbon used for removal of dioxins from flue gas.
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  • Hiroshi Okano, Weili Jin, Tsutomu Hirose
    Type: Technical Research Paper
    Subject area: Safty, Enviroment and Energy
    2002 Volume 28 Issue 6 Pages 726-732
    Published: November 20, 2002
    Released: May 30, 2009
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    An air-conditioning system with a thermally regenerated disccant was examined as a means of utilizing waste heat from micro-gas-turbine dynamos, which are becoming popular as private power sources. The individual machine elements such as desiccant rotors, sensible heat exchangers, evaporative coolers etc. were investigated to propose a new system configuration of air-conditioning. The desiccant air-conditioning system was simplified and the cooling efficiency was improved by regenerating the desiccant rotors with the heat of the waste gas introduced directly into the regeneration air stream from the micro gas turbine dynamo, and by removing the adsorption heat without simultaneous humidification by an indirect evaporative coolers, in contrast to the conventional sxstem in which the regeneration air is warmed by heat exchange with hot water produced by waste heat. A field test unit of desiccant air-conditioning system equipped with a 1,220 mm diameter desiccant rotor was assembled in combination with a 30 kW micro-gas-turbine dynamo to supply about 60 kW cooling capacity.
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  • Daisuke Hirabayashi, Yuji Saito, Shoji Ozawa, Hitoki Matsuda, Naoki Ta ...
    Type: Fundamental Research Paper
    Subject area: Safty, Enviroment and Energy
    2002 Volume 28 Issue 6 Pages 746-752
    Published: November 20, 2002
    Released: May 30, 2009
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    The applicability of hydrated coal burnt ashes as dry gas sorbents for enhanced HCl removal was experimentally studied. In this work, three kinds of coal burnt ash discharged from fluidized bed coal combustion were hydrated with deionized water and with solutions of alcohols such as methanol, ethanol, diethylene glycol, propylene glycol and glycerin at 273 to 353 K. The hydrated sorbent (44–63 m) was tested for HCl removal in a fixed bed reactor under simulated conditions of flue gas capture for a municipal waste incinerator (473 K, 1,000 ppmv HCl). It was found that the improvement of HCl sorption was large with higher CaO content in the hydrated coal burnt ash. The increase in the HCl sorption capacity of coal burnt ash increased with hydration temperature. Maximum HCl sorption was obtained with hydration using glycerin. XRD results showed the generation of Ca(OH)2 with higher crystallinity after hydration. Hydration of coal ash caused remarkable increase in surface area of pores between 0.001 μm and 0.01μm, which played a significant role in high HCl sorption.
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  • Daisuke Hirabayashi, Shoji Ozawa, Hitoki Matsuda, Naoki Tanahashi
    Type: Letter to the Editor
    Subject area: Safty, Enviroment and Energy
    2002 Volume 28 Issue 6 Pages 768-771
    Published: November 20, 2002
    Released: May 30, 2009
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    The chlorination characteristics of CaO-MgO-based compounds from calcined dolomite were experimentally studied in the temperature range of 473 to 1,073 K and compared with those of CaO and MgO. Experimental results showed that the conversion of CaO for chlorination had a maximum value at MgO/CaO molar ratio of 0.74. The maximum HCl sorption capacity per unit weight of calcined dolomite was 1 to 1.3 times as large as that of calcined calcite.
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