巻号一覧
40 巻, 10 号
選択された号の論文の12件中1～12を表示しています
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Transport Phenomena and Fluid Engineering
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Katsumi Shiobara, Setsuro Hiraoka, Yoshihito Kato, Shuichi Iwata, Yuta ...原稿種別: Research Paper
2007 年 40 巻 10 号 p. 793-804
発行日: 2007/10/20
公開日: 2007/10/20
ジャーナル 認証ありThe average boundary layer thickness at the side wall of an agitated vessel without baffles, yD, was estimated from the correlation of the friction factor with the help of the measured universal expression of tangential velocity distribution at a vessel wall. The average boundary layer thickness was independent of the Reynolds number in the turbulent boundary layer range of ReG > 5000, but it increased with decreasing Reynolds number being inversely proportional to the 1/2 power of a generalized Reynolds number in the laminar boundary layer range of ReG < 5000. At the turbulent boundary layer of ReG > 5000, the ratio of the average boundary layer thickness to the vessel radius yD/(D/2) was in the range of 0.013 to 0.018 for the ratio of impeller to vessel diameters d/D = 0.61 to 0.4. The correlation line of the dimensionless tangential velocity at the boundary layer edge uD++ (≡uD+(βD/md)) vs. the dimensionless boundary layer thickness yD++ (≡yD+(βD/md)) coincided with the universal velocity distribution law for a flat plate for the impellers having a larger impeller similarity parameter X over 0.15, but the former shifted upward from the latter for the impellers having a smaller impeller similarity parameter X below 0.15, although the gradient (duD++/d ln yD++) was the same as that for the universal velocity distribution law.抄録全体を表示PDF形式でダウンロード (881K) -
Chii-Dong Ho, Cheng-Lin Ho, Jr-Wei Tu原稿種別: Short Communication
2007 年 40 巻 10 号 p. 805-807
発行日: 2007/10/20
公開日: 2007/10/20
ジャーナル 認証ありA new external-recycle model at the ends of double-pass concentric circular mass exchangers with uniform wall concentration, demonstrating a considerable mass-transfer efficiency improvement, has been developed and studied theoretically. The effects of the subschannel radius ratio, permeable barrier parameter and recycle ratio on the mass-transfer efficiency improvement as well as on the power consumption increment have been also discussed.抄録全体を表示PDF形式でダウンロード (413K)
Particle Engineering
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Yoshiyuki Komoda, Youichi Ikeda, Hiroshi Suzuki, Hiromoto Usui, Tsutom ...原稿種別: Research Paper
2007 年 40 巻 10 号 p. 808-816
発行日: 2007/10/20
公開日: 2007/10/20
ジャーナル 認証ありThe structure of the catalyst layer of PEFCs has a considerable influence on the cell performance. The catalyst layer is manufactured by coating a suspension consisting of Pt/C catalyst particles and a Nafion solution. In a catalyst layer, the decrease in the Pt/C particle agglomeration controlled by the coating condition was reported to improve the performance; however, the influence that the coating condition exerts on the structure and then performance of the catalyst layer when the compositions of suspension are different has not yet been researched well. In this study, we researched a method to control the structure of a catalyst layer by the coating condition and suspension composition. The surface structure, which is well correlated with the predicted number of agglomerated Pt/C particles, showed good agreement with the performance. Under the condition where the Pt/C particles are not dispersed well, the performance was improved with an increase in the coating speed and Nafion content. However, that improvement became negligible at the optimum Nafion content providing maximal cell performance. Further, at a higher Nafion content, the excessive dispersion of Pt/C particles in the catalyst layer deteriorated the performance drastically. These results imply that the performance improvement by coating is effective when the suspension shows fairly high viscosity. Further, a little addition of solvent to decrease the viscosity also improves the performance; however it may be deteriorated by an excessive addition.抄録全体を表示PDF形式でダウンロード (956K)
Separation Engineering
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Cheng-Yuan Wu, Chin-Chun Chung, Tsair-Wang Chung原稿種別: Research Paper
2007 年 40 巻 10 号 p. 817-823
発行日: 2007/10/20
公開日: 2007/10/20
ジャーナル 認証ありThe presence of volatile organic compounds, which affects indoor air quality, is considered to be responsible for a number of health problems. As noted in the literature, the zeolite 13X has good surface properties to adsorb several types of VOCs. Therefore, a series of dynamic measurements of the adsorption of volatile methyl, ethyl, and iso-propyl acetates onto zeolite 13X were conducted in this self-designed apparatus. Instead of using a traditional gas chromatograph, the breakthrough curves for these volatile organic compounds (VOCs) onto zeolite 13X were measured by using a gas phase Fourier Transformation-IR (FT-IR) spectrometer, which responds more quickly to instantaneous changes in the gas concentration. The adsorption experiments were carried out at three different feed concentrations and three gas flow rates for each type of acetate. A significant influence of the breakthrough time on the changes of concentration and flow rate was observed. An empirical model proposed by Yoon and Nelson was applied to fit the experimental data and compared with the application in the authors’ previous study. The results showed that the model can fit the experimental data well under various operating conditions and that the standard deviation values are small.抄録全体を表示PDF形式でダウンロード (1013K)
Process Systems Engineering and Safety
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Manabu Kano, Tomohiro Fukushima, Hiroshi Makita, Shinji Hasebe原稿種別: Research Paper
2007 年 40 巻 10 号 p. 824-831
発行日: 2007/10/20
公開日: 2007/10/20
ジャーナル 認証ありA heat integrated distillation column (HIDiC) is a new and highly energy-efficient distillation process. In the present work, multiple steady-states in HIDiC are analyzed. In HIDiC, the pressure in the rectifying section is kept higher than that in the stripping section by using a compressor to enhance heat transfer from the rectifying section to the stripping section through the wall. Therefore, an energy balance, particularly the influence of the compressor, must be taken into account for the analysis. In this research, two types of operation policies are investigated: P1) constant compressor power and P2) constant pressure ratio. First, the conditions for making multiple steady-states are derived on the basis of the first principle model of the HIDiC. Then, the analysis results are validated through simulations. The results show that: 1) the instability condition depends largely on the compressor operation policies; 2) in case P1, multiple steady-states appear when the top product is highly pure, the bottom product is relatively impure, vapor flow rate is large, and compressor power is small; 3) in case P2, multiple steady-states appear when the bottom product is highly pure; and 4) multiple steady-states appear in a wider range of operation in case P2 than in case P1.抄録全体を表示PDF形式でダウンロード (713K) -
Masaru Sakamoto, Takashi Hamaguchi, Yutaka Ota, Yoshihiro Hashimoto原稿種別: Research Paper
2007 年 40 巻 10 号 p. 832-839
発行日: 2007/10/20
公開日: 2007/10/20
ジャーナル 認証ありIn this paper, a design method of nonlinear controllers is proposed. While physical or chemical analysis is a reliable approach for the construction of nonlinear models, it needs many experiences and might result in very complicated models. The Black-box model approach is adopted in this paper. Identification and controller design of nonlinear processes are very troublesome and complicated. Therefore, a direct design method of nonlinear control, which means not to identify process models, is proposed. The controller is designed using the idea of VRFT (virtual reference feedback tuning). In order to deal with the nonlinearity, input–output data in various operating conditions must be obtained. However, it is very difficult to get sufficient quantities of data for identification of the nonlinearity. Therefore, the model reliability should be evaluated. If the operating condition was not included in the learning data for the nonlinear model identification, the reliability of the model should be judged low. In such a case, it is proposed to suppress the magnitude of the manipulation change. Moreover, in such a case, the online data are stored and are used to re-design the nonlinear model offline. The effectiveness of the proposed controller was shown in a simulation of a tank system.抄録全体を表示PDF形式でダウンロード (1156K) -
Eun Ho Lee, Tae Young Kim, Yeong Koo Yeo原稿種別: Short Communication
2007 年 40 巻 10 号 p. 840-846
発行日: 2007/10/20
公開日: 2007/10/20
ジャーナル 認証ありIn polyolefin processes a melt index (MI) is the most important control variable indicating the product quality. Because of the difficulty in the on-line measurement of the MI, a lot of MI estimation and correlation methods have been proposed. In this work a new dynamic MI estimation scheme is developed based on system identification techniques. The empirical MI estimation equation proposed in the present study is derived from the 1st-order dynamic models. Effectiveness of the present estimation scheme was illustrated by numerical simulations based on plant operation data including grade change operations in high density polyethylene (HDPE) processes. From the comparisons with other estimation methods it was found that the proposed estimation scheme showed better performance in MI predictions.抄録全体を表示PDF形式でダウンロード (1087K)
Micro and Nano Systems
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Yuzuru Shimazaki, Chiyoko Ando, Shu Saeki, Yoshio Kobayashi, Mikio Kon ...原稿種別: Research Paper
2007 年 40 巻 10 号 p. 847-853
発行日: 2007/10/20
公開日: 2007/10/20
ジャーナル 認証ありComparison was made for the citrate stabilized gold colloids prepared sonochemically and thermally. In the sonochemical reduction system, purge gas had large influence on the formation of gold nanoparticles, while little effect was observed for the thermal reduction system. The average diameter of sonochemically prepared gold nanoparticles was smaller than that of thermally prepared gold nanoparticles when prepared at the same concentrations of HAuCl4 and Na3 citrate. The average diameter of the sonochemically prepared gold nanoparticles was increased with an increase in the HAuCl4 concentration ([Na3 citrate]/[HAuCl4] = 7), while the average diameter of the thermally prepared gold colloid was independent of the HAuCl4 concentration. These results were explained by the difference in the reduction rate of gold ions.抄録全体を表示PDF形式でダウンロード (649K) -
Yukiko Marui, Kunio Funakoshi, Takuya Sawada, Masakuni Matsuoka原稿種別: Research Paper
2007 年 40 巻 10 号 p. 854-859
発行日: 2007/10/20
公開日: 2007/10/20
ジャーナル 認証ありA continuous apparatus for the production of nano-particles of organic materials was developed and was applied to leucine. In the new process, a saturated aqueous solutions of leucine continuously flowed over the surface of glycine crystals to dissolve the glycine crystals, and the surface solutions became supersaturated with respect to leucine high enough for leucine to nucleate. Since the nucleated leucine particles were immediately carried away from the surface of the glycine crystal, further growth of the particles was restricted.
The continuous production of leucine particles was demonstrated and the mean diameter of produced primary particles was smaller than 200 nm. When the apparent residence time of produced particles was 0.32 s, the particles were not agglomerated and the mean diameter was 70 nm, which was the smallest mean diameter in the present study.抄録全体を表示PDF形式でダウンロード (1961K)
Energy
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Kazuhiro Sato, Takaaki Shinoda, Kaoru Fujimoto原稿種別: Research Paper
2007 年 40 巻 10 号 p. 860-868
発行日: 2007/10/20
公開日: 2007/10/20
ジャーナル 認証ありGasification of tar by catalytic steam reforming was examined in a circulating fluidized-bed (CFB) biomass gasification process. The tar reforming characteristics of the newly-developed Ni/MgO–CaO catalyst (based on dolomite), doped with WO3 as a sulfur-resistant promoter, was investigated using a simulated gas containing naphthalene as tar. Also, we applied this catalyst to the gasification of a biomass of dried sewage sludge and wood chips. The results of these basic experiments have confirmed that the newly-developed catalyst showed a high tar conversion activity, and is stable even in a gas containing hydrogen sulfide. The catalyst also exhibited superior resistance to coking as well as to sulfur poisoning, compared with several commercial steam reforming catalysts. The gasification demonstration plant (15 ton/d sewage sludge capacity) equipped with the present catalytic reformer showed almost complete tar conversion at 800–850°C in the presence of 300 ppm sulfur.抄録全体を表示PDF形式でダウンロード (1003K) -
Mayumi Tsukada, Aiko Horikawa, Keiichi Sugimoto, Kouetsu Abe, Masashi ...原稿種別: Short Communication
2007 年 40 巻 10 号 p. 869-873
発行日: 2007/10/20
公開日: 2007/10/20
ジャーナル 認証ありCharacterization and measurement of condensable suspended particulate matter emitted from stationary sources, such as coal-fired power plants and waste incinerators, are very difficult since dust concentration in exhaust gas is usually measured at the downstream of dust collectors kept at relatively high temperatures compared with atmospheric air. In the cooling process of flue gas, compounds having solidification points between dust collector temperature and atmospheric temperature have the possibility to become condensable suspended particulate matters. In this work exit gas after bag filtering emitted from a laboratory scale fluidized bed combustor burning refuse-derived fuel (RDF) was sampled by two kinds of cooling methods and elemental analysis was performed. In the experimental results the elemental permeability of a bag filter was high for Pb, Cd, and Zn. To discuss the contribution of fuel composing elements as the origin of measured condensable suspended particulate matters, thermodynamic calculation was performed and the possibility of Cd emission was supported.抄録全体を表示PDF形式でダウンロード (1483K)
Environment
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Masamichi Akimoto, Takayoshi Iida, Shigehiro Sato原稿種別: Short Communication
2007 年 40 巻 10 号 p. 874-878
発行日: 2007/10/20
公開日: 2007/10/20
ジャーナル 認証ありThe liquid-phase hydrothermal dechlorination of a reclaimed oil (Cl content = 2280 ppm) derived from waste lubricating oils was investigated at 275–325°C by using a continuous packed-bed reactor. The reaction proceeded readily in aqueous NaOH solutions, especially at higher NaOH concentrations and at higher reaction temperatures. Thus, the chlorine content in the oil decreased to 57 ppm at 325°C when 0.4 mol/L NaOH was used at the weight feed ratio of 1.3 and at the residence time of 8.0 min. However, the reaction did not proceed further even when the concentrated NaOH solutions of more than 0.4 mol/L were used. The rate of the dechlorination could be well described in terms of a homogeneous SN2-type reaction kinetics involving the participation of water molecules and OH– ions. In contrast to the contribution of water molecules to the reaction, that of OH– ions increased at higher NaOH concentrations and at higher reaction temperatures.抄録全体を表示PDF形式でダウンロード (1317K)
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