研究者データベース

田部 豊(タベ ユタカ)
工学研究院 機械・宇宙航空工学部門 熱流体システム
教授

基本情報

所属

  • 工学研究院 機械・宇宙航空工学部門 熱流体システム

職名

  • 教授

学位

  • 博士(工学)(東京工業大学)

ホームページURL

科研費研究者番号

  • 80374578

ORCID ID

J-Global ID

研究キーワード

  • 固体高分子形燃料電池   物質移動   二次電池   エネルギーシステム解析   

研究分野

  • ものづくり技術(機械・電気電子・化学工学) / 熱工学

職歴

  • 2022年04月 - 現在 東京大学 大学院工学系研究科 教授(委嘱)
  • 2019年04月 - 現在 北海道大学 大学院工学研究院 教授
  • 2007年04月 - 2019年03月 北海道大学 工学(系)研究科(研究院) 准教授
  • 2004年04月 - 2007年03月 北海道大学 工学(系)研究科(研究院) 助教授
  • 2000年04月 - 2004年03月 株式会社荏原製作所
  • 1997年04月 - 2000年03月 日本学術振興会 特別研究員

学歴

  • 1997年04月 - 2000年03月   東京工業大学   理工学研究科機械物理工学専攻博士後期課程
  • 1995年04月 - 1997年03月   東京工業大学   理工学研究科機械物理工学専攻修士課程
  • 1991年04月 - 1995年03月   東京工業大学   工学部機械物理工学科

所属学協会

  • The Electrochemical Society   エネルギー・資源学会   自動車技術会   日本伝熱学会   日本機械学会   

研究活動情報

論文

  • Biness LUKWESA, Naoya TAKAHASHI, Kengo SUZUKI, Yutaka TABE, Takemi CHIKAHISA
    Mechanical Engineering Journal 9 1 21 - 00154 2022年 [査読有り]
  • Yutaka Iizuka, Yuki Kitami, Suguru Uemura, Yutaka Tabe
    ECS Transactions 104 8 83 - 92 2021年10月01日 [査読有り][通常論文]
  • Shu Mizuno, Suguru Uemura, Yutaka Tabe
    ECS Transactions 104 8 175 - 183 2021年10月01日 [査読有り][通常論文]
  • Yutaka Tabe, Naoyuki Wakatake, Yuta Ishima, Takemi Chikahisa
    Journal of The Electrochemical Society 2021年06月01日 [査読有り][通常論文]
  • Study on water transport in hydrophilic gas diffusion layers for improving the flooding performance of polymer electrolyte fuel cells
    Satoshi Sakaida, Yutaka Tabe, Kotaro Tanaka, Mitsuru Konno
    International Journal of Hydrogen Energy 46 7464 - 7474 2021年01月 [査読有り][通常論文]
  • レドックスフロー電池における構造・運転条件影響の集約主要因子を用いた性能評価
    西田尚功, 田部豊, 善当哲也, 日原颯也, 近久武美
    日本機械学会論文集 86 888 2020年07月 [査読有り][通常論文]
  • Jiaming Gong, Nobuyuki Oshima, Yutaka Tabe
    Computers & Mathematics with Applications 78 4 1166 - 1181 2019年08月 [査読有り][通常論文]
     
    The spurious velocity resulting from the cutoff and magnification equation in the free-energy-based one-component-two-phase flow lattice Boltzmann method (LBM) for a large density ratio proposed by Inamuro et al. [34] is investigated. In Inamuro's model, the phase interface is tracked by the order parameter, which is the dimensionless density of a two-phase flow system with a small density ratio. The velocity field is calculated based on the density profile of a two-phase system with a large density ratio, which is derived from the order parameter profile through a sine type of cutoff and magnification equation; this velocity field is then used to drive the movement of a phase interface described by the order parameter. The implementation of the cutoff and magnification equation causes the density profiles in the two systems to differ from each other such that force balances across the interfaces break from the ideal state and lead to spurious velocity. Three measures: (1) the linear cutoff and magnification equation which equalizes the density profiles in the interface region, (2) a new scheme which enhances the smoothness of the density profile around the cutoff points in the large density ratio system and (3) a special method that increases the interface thickness of the large density ratio system are adopted to reduce the magnitude of the spurious velocity from the profile difference, respectively. We show that all of these measures can successfully reduce the magnitude of the spurious velocity to some degree; and the scheme that enhances the smoothness of the density profile around the cutoff points reduces the spurious velocity of the original scheme by one order of magnitude.
  • Satoshi Sakaida, Kotaro Tanaka, Mitsuru Konno, Yutaka Tabe
    ECS Transactions 92 8 205 - 212 2019年07月03日 [査読有り][通常論文]
  • Yuki Kitami, Yutaka Tabe, Takemi Chikahisa
    ECS Transactions 2019年07月03日 [査読有り][通常論文]
  • Satoshi Sakaida, Yutaka Tabe, Takemi Chikahisa, Kotaro Tanaka, Mitsuru Konno
    Journal of The Electrochemical Society 166 10 F627 - F636 2019年 [査読有り][通常論文]
  • Takayasu Satake, Yutaka Tabe, Takemi Chikahisa
    ECS Transactions 86 13 171 - 178 2018年07月23日 [査読有り][通常論文]
  • Satoshi Sakaida, Yutaka Tabe, Takemi Chikahisa, Kotaro Tanaka, Mitsuru Konno
    ECS Transactions 86 13 111 - 118 2018年07月23日 [査読有り][通常論文]
  • Takumi Iiri, Yutaka Tabe, Takemi Chikahisa
    ECS Transactions 86 13 141 - 150 2018年07月23日 [査読有り][通常論文]
  • Fumito Onishi, Yutaka Tabe, Takemi Chikahisa
    ECS Transactions 86 13 89 - 96 2018年07月23日 [査読有り][通常論文]
  • 藤原貴弘, 田部豊, 近久武美
    日本機械学会論文集(Web) 84 859 ROMBUNNO.17‐00449(J‐STAGE)  2018年 [査読有り][通常論文]
  • Yutaka TABE, Satoshi SAKAIDA, Takemi CHIKAHISA
    Journal of Thermal Science and Technology 13 2 JTST0025 - JTST0025 2018年 [査読有り][通常論文]
  • Yusuke Aoyama, Yutaka Tabe, Ryo Nozaki, Kengo Suzuki, Takemi Chikahisa, Toshihiro Tanuma
    Journal of The Electrochemical Society 165 7 F484 - F491 2018年 [査読有り][通常論文]
  • Shahab Bayani, Yutaka Tabe, Yong Tae Kang, Seong Hyuk Lee, Chang Kyoung Choi
    Journal of Flow Visualization and Image Processing 25 3-4 191 - 205 2018年 [査読有り][通常論文]
  • Satoshi Sakaida, Yutaka Tabe, Takemi Chikahisa
    Journal of Power Sources 361 133 - 143 2017年09月 [査読有り][通常論文]
  • Ryo Nozaki, Yutaka Tabe, Takemi Chikahisa, Toshihiro Tanuma
    ECS Transactions 80 8 335 - 344 2017年08月24日 [査読有り][通常論文]
  • Satoshi Sakaida, Yutaka Tabe, Takemi Chikahisa
    ECS Transactions 80 8 123 - 131 2017年08月24日 [査読有り][通常論文]
  • Yutaka Tabe, Takayasu Satake, Takumi Iiri, Tomoya Hayashi, Takemi Chikahisa
    ECS Transactions 80 8 205 - 214 2017年08月24日 [査読有り][通常論文]
  • 赤澤眞之, 鈴木研悟, 田部豊, 近久武美
    日本機械学会論文集(Web) 83 847 ROMBUNNO.16‐00430(J‐STAGE)  一般社団法人 日本機械学会 2017年 [査読有り][通常論文]
     

    A combined heat and power (CHP), sometimes called cogeneration, is one of the effective technologies for reducing CO2 emission. In the previous research, the authors proposed a concept of "Networked CHP system", which allows surplus electricity of CHP to be reversed to the power grid and to consume it effectively in the network. Result of the analysis clarified significant CO2 reduction with minimum social cost compared to the non-networked system. The social cost is the amount supplying energy to the area, and it is different from the benefit of individual customer. Customers select the capacity and operation of CHP to have the minimum cost for them, and it is mostly different from the social optimum. This paper analyzes the conditions of energy prices to direct customer selection to the social optimum for cost and CO2 reduction. The results of the analysis show that the electricity/gas price ratio normalized by CO2 emission factor should be unity, and the sell/buy ratio of electricity between the grid for the customer should be larger than 0.6. As an example of measures to keep the profit of electric company for increasing CHP, FIT price of about 1% is enough to be added on the electricity and gas prices. To make customers to select the optimum capacity of the CHP, clear guideline of the optimum kW for unit floor area should be indicated and the CHP price should be in the acceptable range for customers; this is due to the fact that effective subsidy for CHP selection is hardly determined, as the minimum cost for customers does not vary much for the capacity of the CHP.

  • 田部豊, 内山真理, 嶋田遼, 鈴木研悟, 近久武美
    日本機械学会論文集(Web) 83 849 ROMBUNNO.16‐00458(J‐STAGE)  2017年 [査読有り][通常論文]
  • S. Sakaida, Y. Tabe, T. Chikahisa
    ECS Transactions 75 14 219 - 226 2016年09月23日 [査読有り][通常論文]
  • T. Hayashi, Y. Tabe, T. Chikahisa
    ECS Transactions 75 14 373 - 383 2016年09月23日 [査読有り][通常論文]
  • N. Wakatake, Y. Tabe, T. Chikahisa
    ECS Transactions 75 14 623 - 630 2016年09月23日 [査読有り][通常論文]
  • Masaya Kozakai, Kenji Date, Yutaka Tabe, Takemi Chikahisa
    INTERNATIONAL JOURNAL OF HYDROGEN ENERGY 41 30 13180 - 13189 2016年08月 [査読有り][通常論文]
     
    The performance of polymer electrolyte membrane (PEM) fuel cells highly depends on their mass transport property at high current density operation. To improve the mass transport property, various types of flow-fields have been developed, such as serpentine, straight, grid, and porous flow-fields. Because of the limits of thin land and channel width, the authors have developed a porous type flow-field with unique pore diameter distribution. Unlike general types of porous flow-fields, it has a double peak in the pore diameter distribution; in this paper, it is called a "bi-porous flow-field". The structure was intended to have organized flow paths for liquid water and gas. The paper investigates its performance and impedance characteristics compared with those of the conventional flow fields. The results of the analysis on the polarization and electrochemical impedance spectrometry revealed that the bi-porous flow-field exhibits the smallest gas diffusion resistance at a high current density operation regardless of humidity conditions. These results indicate that the bi-porous flow-field conducts water management well at high current density. In low humidity conditions, however, dry-out tends to occur and must be prevented. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
  • 坂本 篤, 田部 豊, 近久 武美
    北海道支部講演会講演概要集 2016 103 - 104 一般社団法人 日本機械学会 2016年
  • Kumar Abhay, Tabe Yutaka, Chikahisa Takemi
    北海道支部講演会講演概要集 2016 107 - 108 一般社団法人 日本機械学会 2016年
  • 藤原 貴弘, 田部 豊, 近久 武美
    北海道支部講演会講演概要集 2016 119 - 120 一般社団法人 日本機械学会 2016年
  • 善当 哲也, 田部 豊, 近久 武美
    北海道支部講演会講演概要集 2016 101 - 102 一般社団法人 日本機械学会 2016年
  • 笠井 風太, 田部 豊, 近久 武美
    北海道支部講演会講演概要集 2016 99 - 100 一般社団法人 日本機械学会 2016年
  • 野崎 涼, 田部 豊, 近久 武美
    北海道支部講演会講演概要集 2016 97 - 98 一般社団法人 日本機械学会 2016年
  • 赤澤眞之, 鈴木研悟, 田部豊, 近久武美
    日本機械学会論文集(Web) 82 836 15‐00442(J‐STAGE) - 00442-15-00442 一般社団法人 日本機械学会 2016年 [査読有り][通常論文]
     
    A combined heat and power (CHP), sometimes called as cogeneration, is generally independently installed into buildings without networked to the power grid, but unbalanced heat/electricity ratio of the CHP output and the demand significantly limits CHP's performance. This study investigates the effect of the networked CHP system to the power grid on CO2 reduction and cost. The networking concept of CHPs is that CHPs are installed to buildings with large heat demand, and excessive electricity is consumed in buildings in the network via power grid. The analysis was applied for a model area in Sapporo, which is an urban residential area covered by electric feeders from a distributing power substation. The results show that the networked CHP system can reduce CO2 significantly compared to the non-networked system with the same cost. This is due to the fact that CHPs can be operated for the heat demand without limited by the electricity demand of the building by the networking, and their capacities of the system can be utilized effectively. Therefore, the maximum CO2 reduction extent is also increased. These results indicate the significance of the networking concept. Sensitivity analysis of the results for the unit costs and CO2 emission factors of the grid power was also made, and the networking effect was confirmed for various conditions. The paper also investigates the suitable type of CHPs installed to households, showing that fuel cell can reduce larger amount of CO2 than gas engine with the networking condition.
  • Yusuke Aoyama, Kengo Suzuki, Yutaka Tabe, Takemi Chikahisa, Toshihiro Tanuma
    JOURNAL OF THE ELECTROCHEMICAL SOCIETY 163 5 F359 - F366 2016年 [査読有り][通常論文]
     
    For interfaces between micro-porous layers (MPL) and catalyst layers (CL) made by the gas diffusion electrode (GDE) method, a seamless interface without gaps, shows better performance than that of cells with an interface made by the decal transfer method. With the decal transfer method, the MPL is simply hot-pressed to the CL-membrane assembly. This study investigates the effect of interface structure on cell performance and water transport in the MPL. Water distribution in cross sections of multiple layers were observed by a freezing method, where the cell is cooled below freezing temperature in short time and the water was observed in ice form by Cryo-SEM. The results show that a membrane electrode assembly (MEA) using the GDE method improves cell performance at high current densities. Direct observations by the freezing method and cryo-SEM show that there is no water accumulation at the MPL/CL interface made by the GDE method, while water accumulates at the interface made by the decal method. Other observations show that the water amount inside the MPL increases similarly in the two types of MEA when lowering the temperature, and the difference between the two types of MEA was only the water amount in the interface. (C) The Author(s) 2016. Published by ECS. All rights reserved.
  • Yutaka Tabe, Kazuki Yamada, Ryosuke Ichikawa, Yusuke Aoyama, Kengo Suzuki, Takemi Chikahisa
    JOURNAL OF THE ELECTROCHEMICAL SOCIETY 163 10 F1139 - F1145 2016年 [査読有り][通常論文]
     
    For further improvements in the startup ability below freezing and the durability of polymer electrolyte fuel cells, understanding the ice formation mechanism during cold startup is particularly significant. This study observes cross-sectional ice distributions in a catalyst layer (CL) during isothermal galvanostatic operation at -20 degrees C using a cryo-scanning electron microscope. The effects of current density, cathode gas conditions, initial water content of the membrane, and cell temperature on the cold start characteristics and the ice formation process in the CL are evaluated. The observational results show that at higher current densities, the region with active ice formation moves from the membrane to the gas diffusion layer sides during the freezing period and vacant pores remain near the membrane even after cell shutdown, while the pores are completely filled with nearly-uniformly growing ice at lower current density operation. This is consistent with the experimental finding from the cold start characteristics that the estimated amount of ice accumulated in the cell until the shutdown decreases as the current density increases. Contrary to expectations, these changes are largely independent of cathode gas conditions, even with pure oxygen. Additional factors controlling the ice formation process are discussed based on the experimental results. (C) The Author(s) 2016. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. All rights reserved.
  • Yutaka Tabe, Yusuke Aoyama, Kazumasa Kadowaki, Kengo Suzuki, Takemi Chikahisa
    JOURNAL OF POWER SOURCES 287 422 - 430 2015年08月 [査読有り][通常論文]
     
    In polymer electrolyte membrane fuel cells, a gas diffusion layer (GDL) with a micro-porous layer (MPL) gives better anti-flooding performance than GDLs without an MPL. To investigate the function and mechanism of the MPL to suppress water flooding, the liquid water distribution at the cathode catalyst layer (CL) surface are observed by a freezing method; in the method liquid water is immobilized in ice form by rapid freezing, followed by disassembling the cell for observations. The ice covered area is quantified by image processing and cells with and without an MPL are compared. The results show that the MPL suppresses water accumulation at the interface due to smaller pore size and finer contact with the CL, and this results in less water flooding. Investigation of ice formed after -10 degrees C cold start shutdowns and the temporary performance deterioration at ordinary temperatures also indicates a significant influence of the liquid water accumulating at the interface. The importance of the fine contact between CL and MPL, the relative absence of gaps, is demonstrated by a gas diffusion electrode (GDE) which is directly coated with catalyst ink on the surface of the MPL achieving finer contact of the layers. (C) 2015 Elsevier B.V. All rights reserved.
  • Yusuke Aoyama, Kengo Suzuki, Yutaka Tabe, Takemi Chikahisa, Toshihiro Tanuma
    ECS Transactions 69 17 743 - 752 2015年 [査読有り][通常論文]
     
    This paper investigated the mechanism of the hydrophilic MPL with carbon fiber (CF) to increase cell performance by comparing the cell performance and water distribution inside the MPL with different pore size and thickness. The results show that the hydrophilic thick CFMPL improves cell performance by preventing the increase of concentration overvoltage under high current density region. The direct observations by the freezing method and cryo- SEM shows that water is observed in pores of the CFMPL at the catalyst layer (CL) side, while there is no water in the thick CFMPL at the gas diffusion layer (GDL) side. This suggests that the hydrophilic thick CFMPL evaporates water in the CFMPL before the water reaches to the GDL side by the large pores and the adequate thickness of the CFMPL, resulting in better anti-flooding performance.
  • Yutaka Tabe, Sho Akabori, Tomoya Hayashi, Kengo Suzuki, Takemi Chikahisa
    ECS Transactions 69 17 773 - 781 2015年 [査読有り][通常論文]
     
    For efficient use of Pt catalyst in polymer electrolyte membrane fuel cells (PEFCs), the effects of the cathode catalyst layer (CL) structure on the cell performance were evaluated experimentally. In particular we focused on two parameters used in analysis by agglomerate models, the agglomerate size and the oxygen dissolution resistance to the ionomer surrounding the carbon agglomerate. Various ratios of ionomer to carbon were selected as the CL fabrication condition with same amount of Pt-supported carbon. To estimate the agglomerate size, pore size distribution (PSD) was measured by nitrogen physisorption method, and an estimation method of agglomerate size distribution from the measured PSD was applied. It was shown that the model analysis using the estimated parameters with relatively-small agglomerate size can well simulate the measured IV characteristics, and that the balance of the oxygen diffusion and dissolution resistances in the ionomer dominates the cell performance under the condition here.
  • Jia-ming Gong, Nobuyuki Oshima, Yutaka Tabe
    JOURNAL OF THERMAL SCIENCE AND TECHNOLOGY 10 1 1 - 14 2015年 [査読有り][通常論文]
     
    The spurious velocity around curved interface, arising from the calculation of the Poisson equation with staggered grids, is reduced in the free-energy-based two-phase flow lattice Boltzmann method (LBM) for large density ratios. It is found that the pressure calculation from the Poisson equation, using the successive over-relaxation method with staggered grids, would introduce anisotropic discretization errors and lead to deviations of its calculated value from the theoretical prediction. Moreover, the anisotropic pressure would induce a large magnitude of spurious velocity, which is the driving force for droplet shape deformation. By blending the velocity components in the discretization equations of the Poission equation from two types of staggered grids that separately make use of the velocity components in the orthogonal and the diagonal directions, the magnitude of the spurious velocity and the droplet deformation are diminshed. It is found that, by appropriate choice of the blending factor, the magnitude of the spurious velocity can be reduced to half of its original value, and the shape deformation and pressure deviation from the theoretical prediction can be minimized.
  • Y. Aoyama, K. Suzuki, Y. Tabe, T. Chikahisa, T. Tanuma
    ECS Transactions 64 3 527 - 535 2014年08月18日 [査読有り][通常論文]
  • S. Akabori, K. Suzuki, Y. Tabe, T. Chikahisa
    ECS Transactions 64 3 305 - 312 2014年08月18日 [査読有り][通常論文]
  • Yusuke Aoyama, Kengo Suzuki, Yutaka Tabe, Takemi Chikahisa
    ELECTROCHEMISTRY COMMUNICATIONS 41 72 - 75 2014年04月 [査読有り][通常論文]
     
    Micro-porous layers (MPLs) play an important role in the water management of polymer electrolyte fuel cells (PEFCs), however, the detailed mechanism of how the produced water is drained from these layers is not well understood. This paper observed the cross-sectional distribution of liquid water inside the cathode MPL to elucidate details of the phase state of the water transported through the MPL The freezing method and ctyo-scanning electron microscope (cryo-SEM) are used for the observations; the freezing method enables immobilization of the liquid water in the cell as ice forms by the freezing, and the cryo-SEM can visualize the water distribution in the vicinity of the MPL at high resolution without the ice melting. It was shown that no liquid water accumulates inside the MPL in operation at 35 degrees C, while the pores of the MPL are filled with liquid water under very low cell temperature operation, at 5 degrees C. These results indicate that the produced water passes through the MPL not as a liquid but in the vapor state in usual PEFC operation. Additionally, liquid water at the interface between the MPL and a catalyst layer (CL) was identified, and the effect of the interfacial contact on the water distribution was examined. (C) 2014 Elsevier B.V. All rights reserved.
  • 鈴木研悟, 中西 嵩裕, 田部豊, 近久武美
    日本機械学会論文集 80 812 1 - 14 The Japan Society of Mechanical Engineers 2014年 [査読有り][通常論文]
     
    For the purpose of preparing for the further diffusion of wind power technology, the power reduction risk of wind power plants, i.e. a risk of frequent and large reduction in the output caused by time-varying wind speeds, needs to be decreased. Among measures against the risk, the geographical distribution of wind power plants needs to be examined first because additional facilities, such as backup power plants or electricity storages, are not required. This study quantitatively analyzes the risk reduction effect of geographically distributing wind power plants among 12 locations within the Hokkaido. The mean-CVaR (Conditional Value at Risk) model is adopted to estimate the optimum geographical distribution. We found that the share of time period with no power output can be reduced to mostly 0% by optimizing the geographical distribution while the share is more than 10% if all the wind power plants are intensively installed to the location with the highest average output. Another finding is that the geographical distribution can contribute to the risk reduction even among the locations in the Hokkaido that is a relatively smaller region compared with the regions surveyed by earlier studies. We also found that the CVaR is the better index of the power reduction risk of wind power plants than the standard deviation as far as focusing on the power reduction risk.
  • Yutaka Tabe, Takuya Nasu, Satoshi Morioka, Takemi Chikahisa
    JOURNAL OF POWER SOURCES 238 21 - 28 2013年09月 [査読有り][通常論文]
     
    Polymer electrolyte membrane fuel cells (PEFCs) with a porous flow field have been proposed as an alternative to cells with gas flow channels. In this study, the basic characteristics of a PEFC with a porous flow field are identified experimentally. It is shown that stable operation is maintained under conditions at high current density and low stoichiometric ratios of the cathode air, but that operation with low relative humidity gases is difficult in the porous type cell. To clarify the detailed causes of these characteristics, internal phenomena are investigated using a cell specially made for cross-section observations of the cathode porous flow field and temperature distribution measurements on the anode gas diffusion layer (GDL) surface. The direct observations show that the porous type cell is superior in draining the condensed water from the GDL surface, and that hydrophilic properties of the porous material are important for better cell performance at high current densities. The temperature measurements indicate that increases in temperature near the reaction area tend to be larger in the porous type cell than in the channel type cell due to the lower heat removal capability of the porous material, resulting in the unstable operation at relatively low humidities. (C) 2013 Elsevier B.V. All rights reserved.
  • Yusuke Aoyama, Kengo Suzuki, Yutaka Tabe, Takemi Chikahisa, Toshihiro Tanuma
    ECS Transactions 58 1 1383 - 1390 2013年 [査読有り][通常論文]
     
    Although micro-porous layers (MPLs) have a role to suppress water flooding, the mechanism has not been fully understood. We observed the cross-sectional liquid water distribution inside a cathode side MPL to clarify the effect of the MPL/catalyst layer (CL) interfacial structure on water transport in the MPL. The freezing method and cryo-SEM are used for the observation. The membrane electrode assemblies (MEAs) made by two different methods (decal transfer method and GDE method) were also used. The result showed that in the MEA prepared by the decal method, liquid water is distributed inside the MPL under the land, and at the MPL/CL interface under the gas-flow channel. In contrast, in the MEA made by the GDE method, the liquid water distributions in the MPL are similar both under the land and channel. These results indicate that interfacial structure has a strong effect on liquid water distribution in the MPL. © The Electrochemical Society.
  • Kazuki Yamada, Kengo Suzuki, Yutaka Tabe, Takemi Chikahisa
    POLYMER ELECTROLYTE FUEL CELLS 13 (PEFC 13) 58 1 463 - 471 2013年 [査読有り][通常論文]
     
    In polymer electrolyte fuel cells, the freezing of produced water deteriorates the cell performance below zero. In this study, we investigated the freezing phenomena in the cathode catalyst layer (CL) by experiments, and identified the effects of current density, cathode gas pressure, and oxygen concentration. It was shown that the ice distribution and the estimated amount of ice produced in the CL till the shutdown depends on the current density, while they are independent of the cathode gas pressure and the oxygen concentration. To clarify the main cause dominating these tendencies, we introduced the effect of ice formation on an increase in the through-plane electrical resistance of the CL into the three phase boundary and the CL models, and examined the mechanism in the CL. The calculation results correspond to the experimental current density dependency, and the ice distribution is independent of the gas pressure and the oxygen concentration.
  • 柏瀬浩司, 田部豊, 近久武美
    日本機械学会論文集(B編) 79 806 2217 - 2227 2013年 [査読有り][通常論文]
     
    This paper investigates water transport phenomena in PEM (Polymer Electrolyte Membrane) electrolysis cell. Experimental result showed that the cell voltage is less affected by the concentration overpotential even at quite high current densities, although significant amount of produced gas is observed in the water flow channels. Impedance measurement indicated that water content in the membrane increases with an increase in current density. The water flux measured at the cathode exit was almost identical to the osmotic flux in the membrane with saturated water content. In order to discuss the mechanism of the enough water-supply under the high current density conditions, numerical analysis was conducted on the water transport in the anode catalyst layer and the membrane. The result showed that the order of the water hydration rate into Nafion ionomer is greater than 1×10-4m/s, and sufficient amount of water is supplied from pores in the catalyst layer to the ionomer surrounding catalyst particles at the anode side. This water supply mechanism results in the membrane water-content close to the saturated state, and the water in the membrane is mainly transported by osmotic force. It was also shown that water content in the membrane at the cathode boundary has little influence on the water flux and overall water distribution through the membrane. © 2013 The Japan Society of Mechanical Engineers.
  • Yutaka Tabe, Masataka Saito, Kaoru Fukui, Takemi Chikahisa
    JOURNAL OF POWER SOURCES 208 366 - 373 2012年06月 [査読有り][通常論文]
     
    Cold start characteristics of a polymer electrolyte membrane fuel cell are investigated experimentally, and microscopic observations are conducted to clarify the freezing mechanism in the cell. The results show that the freezing mechanism can be classified into two types: freezing in the cathode catalyst layer at very low temperature like -20 degrees C. and freezing due to supercooled water at the interface between the catalyst layer and the gas diffusion layer near 0 degrees C like -10 degrees C. The amount of water produced during the cold start is related to the initial wetness condition of the polymer electrolyte membrane, because water absorption by the membrane due to back diffusion plays an important role to prevent the water from freezing. It is also shown that after the shutdown of the cold start the cell performance of a subsequent operation at 30 C is temporarily deteriorated after the freezing at -10 degrees C, but not after the freezing at -20 degrees C. The ice formed at the interface between the catalyst layer and the gas diffusion layer is estimated to cause the temporary deterioration, and the function of a micro porous layer coating the gas diffusion layer for the ice formation is also discussed. (C) 2012 Elsevier B.V. All rights reserved.
  • Litan Kumar Saha, Yutaka Tabe, Nobuyuki Oshima
    JOURNAL OF POWER SOURCES 202 100 - 107 2012年03月 [査読有り][通常論文]
     
    In this study the deformation effect of a gas diffusion layer (GDL) on the pressure drop of a polymer electrolyte fuel cell (PEFC) separator channel has been investigated both numerically and experimentally. Pressure drop is considered as a diagnostic tool to monitor the performance of a PEFC. The deformation of the GDL caused by the compression pressure plays an important role in the performance of a PEFC since it affects the physical properties of the GDL, such as porosity, permeability and the cross sectional area of the gas channel. The flow behavior in the separator channel and GDL of PEFCs has been investigated by using a transient, isothermal and three-dimensional numerical model. To develop the numerical simulation of PEFC, verification experiments and data acquisition of physical parameters were conducted by mechanical measurements. The experimental results showed that estimating the actual flow configuration in the cell, the GDL deformation shape due to clamping by the separator lands has a significant influence. The numerical result shows that together with the deformation shape, the GDL physical parameter variation also needs to be considered in order to predict the actual flow phenomena. Moreover, the results can estimate the physical parameters under deformed condition qualitatively. (C) 2011 Elsevier B.V. All rights reserved.
  • Yasser Ben Salah, Yutaka Tabe, Takemi Chikahisa
    JOURNAL OF POWER SOURCES 199 85 - 93 2012年02月 [査読有り][通常論文]
     
    Water management in polymer electrolyte membrane (PEM) fuel cells is important for fuel cell performance and durability. Numerical simulations using the lattice Boltzmann method (LBM) are developed to elucidate the dynamic behavior of condensed water and gas flows in a PEM fuel cell gas channel. A scheme for two-phase flow with large density differences was applied to establish the optimum gas channel design for different gas channel heights, droplet initial positions, droplet volume and air flow velocity for both hydrophobic and hydrophilic gas channels. The discussion of optimum channel height and drain performance was made using two factors "pumping efficiency" and "drainage speed". It is shown that deeper channels give better draining efficiency than shallower channels, but the efficiency dramatically decreases when the droplet touches corners or the top of gas channel's walls. As the droplet velocity, i.e. the drainage flow rate becomes higher and the drainage efficiency becomes less dependent on droplet locations with shallower channels, shallower channels are better than deeper channels. Introducing a new dimensionless parameter, "pumping efficiency", the investigation discusses the effect of the various parameters on the drainage performance of a PEM fuel cell gas channel. (C) 2011 Elsevier B.V. All rights reserved.
  • Y. Aoyama, K. Kadowaki, Y. Tabe, T. Chikahisa
    ECS Transactions 50 2 445 - 452 2012年 [査読有り][通常論文]
     
    Micro-porous layers (MPLs) play an important role in the water management of polymer electrolyte fuel cells (PEFCs), but details of the mechanism to suppress water flooding has not been fully understood. In this study, we observed distributions of condensed water at the cross-section surface of the MPL using freezing method and a CRYO-SEM to clarify the effect of the MPL on discharge of produced water. By comparing two observations under normal operational condition and water flooding condition, we discuss water transfer phenomena in the MPL. The observation result shows that condensed water accumulates not in the MPL under normal operational condition but in the MPL under water flooding condition such as lower cell temperature operation. This indicates that water transfer phenomena in the MPL depend on cell temperature under low temperature conditions such as 10 °C, produced water condenses in the MPL because of small vapor transport capacity through the MPL due to low temperature. © The Electrochemical Society.
  • M. Kobayashi, Y. Tabe, T. Chikahisa
    ECS Transactions 50 2 415 - 422 2012年 [査読有り][通常論文]
     
    Achieving the optimum structure of electrode catalyst layer and the efficient transport of the reactants is significantly effective to reduce the usage of Pt catalyst in polymer electrolyte membrane fuel cells. In this paper, we fabricated the catalyst coated membrane (CCM) and estimated structural parameters of the catalyst layer from observation of the CCM by a SEM. The characteristics of the cell performance were calculated using an agglomerate model with the estimated parameters, and the simulation model was validated by comparing the simulated and experimental results. Then, we evaluated the effects of the major parameters such as the polymer electrolyte film thickness covering carbon agglomerates on the cell performance by the simulation, and present a new concept effective for reducing the identified major resistances of oxygen supply by controlling the film structure of polymer electrolyte. © The Electrochemical Society.
  • Yasser Ben Salah, Yutaka Tabe, Takemi Chikahisa
    FUEL CELLS 2012 SCIENCE & TECHNOLOGY - A GROVE FUEL CELL EVENT 28 125 - 133 2012年 [査読有り][通常論文]
     
    A scheme for two-phase flow with large density differences using the lattice Boltzmann method (LBM) was applied to investigate the optimum gas channel design for water drainage. Three different channel geometries were used: rectangular, trapezoidal, and triangular with constant gas flow rate and a droplet initially placed at the corner. The results show that the rectangular channel offers the best water removal characteristics under a moderate pressure drop. When using hydrophilic gas channels, a larger droplet is drawn up, which may induce better fuel cell performance. The cases of both channels with the same cross-section area, height and width are discussed. (C) 2012 Published by Elsevier Ltd.
  • Yutaka Tabe, Ryosuke Ichikawa, Takemi Chikahisa
    FUEL CELLS 2012 SCIENCE & TECHNOLOGY - A GROVE FUEL CELL EVENT 28 20 - 27 2012年 [査読有り][通常論文]
     
    Ice distribution in a cathode catalyst layer of a polymer electrolyte membrane fuel cell is investigated during the process of cold start operation using a cryo-SEM. The observation results show that at higher startup current densities, ice grows from the membrane side to the gas diffusion layer side and that this becomes more pronounced when increasing the current density, while the ice distribution in the cell is nearly uniform at a lower current density. The ice formation processes observed by the cryo-SEM are analyzed using three-phase boundary and catalyst layer models, and the freezing mechanism at cold starting is discussed. (C) 2012 Published by Elsevier Ltd.
  • Kyaw Swar Soe Naing, Yutaka Tabe, Takemi Chikahisa
    JOURNAL OF POWER SOURCES 196 5 2584 - 2594 2011年03月 [査読有り][通常論文]
     
    To maintain the efficiency of proton exchange membrane fuel cells (PEFCs) without flooding, it is necessary to control the liquid water transport in the gas diffusion layer (GDL). This experimental study investigates the effects of the GDL fiber direction on the cell performance using an anisotropic GDL The results of the experiments show that the efficiency of the cell is better when the fiber direction is perpendicular to the channel direction, and that the cells with perpendicular fibers are more tolerant to flooding than cells with fibers parallel to the channel direction. To determine the mechanism of the fiber direction effects, the liquid water behavior in the channels was observed through a glass window on the cathode side. The observations substantiate that the liquid water produced under the ribs is removed more smoothly with the perpendicular fiber direction. Additionally, the water inside the GDL was frozen to observe its distribution using a specially made cell broken into two pieces. The photographic results show that the amount of water under the ribs is larger than that under the channels using the parallel fiber direction GDL while the water distributions in these two places are almost equal level with the perpendicular fiber direction GDL This freezing method confirmed the better liquid water removal ability and better reactant gas transportation in the GDL with the fiber direction perpendicular to the channel direction. (C) 2010 Elsevier B.V. All rights reserved.
  • Yutaka Tabe, Masataka Saito, Ryosuke Ichikawa, Takemi Chikahisa
    PROCEEDINGS OF THE ASME/JSME 8TH THERMAL ENGINEERING JOINT CONFERENCE 2011, VOL 2 463 - 468 2011年 [査読有り][通常論文]
     
    In Polymer electrolyte membrane fuel cells (PEFCs), freezing of produced water induces the extreme deterioration of cell performance below zero. This phenomenon is a serious problem in cold regions and is needed to be solved to achieve the practical use of PEFCs. In this study, we investigated ice distribution at the cold start in a PEFC using an optical microscope and a CRYO-SEM to clarify the freezing mechanism. The observation results showed that the cold start at -10 degrees C makes ice at the interface between the cathode catalyst layer (CL) and the micro porous layer of gas diffusion layer Little ice was, however, observed in the cold start at -20 degrees C, which indicated the ice formation inside the CL. The CRYO-SEM observation was conducted at -20 degrees C to investigate the ice formation inside the CL, and this identified the effects of the current density and the cathode gas species on the ice distribution.
  • Takemi Chikahisa, Yutaka Tabe, Kazushige Kikuta, A. S. M. Sayem
    PROCEEDINGS OF THE ASME/JSME 8TH THERMAL ENGINEERING JOINT CONFERENCE 2011, VOL 2 589 - + 2011年 [査読有り][通常論文]
     
    To design a diesel engine adapting to future exhaust gas regulation, it is important to develop a driving mode simulator which can simulate vehicle performance and exhaust emissions including after-treatment system. The combustion model for this objective must be able to simulate heat release rate, variety of emissions necessary for after-treatment simulation, and exhaust gas temperature in very short computational time. The authors have developed a diesel combustion model based on the Hiroyasu model by adding variety of modifications to minimize optimization process of the empirical constants. It was shown that the simulation results with the improvement model were in good agreement with the experimental results. By adding Tsurushima model consisting of nine reaction steps with several intermediate species, the model became available for the both combustions of spray diffusion flame and of homogeneous charge compression ignition..
  • Yutaka Tabe, Masayoshi Nishino, Hiroyuki Takamatsu, Takemi Chikahisa
    JOURNAL OF THE ELECTROCHEMICAL SOCIETY 158 10 B1246 - B1254 2011年 [査読有り][通常論文]
     
    Transport of electrons, protons, and oxygen are necessary for the cathode reactions in polymer electrolyte membrane fuel cells, and achieving the optimum structure of the electrode catalyst layer and the efficient transport of reactants is an effective avenue to reduce the use of platinum catalyst. This study applied three-phase boundary and cathode catalyst layer models to understand details of optimally efficient structures for the transport of reaction components. The factors dominating the effects of the catalyst layer structure and the properties identified in this manner are investigated using the models. Additionally, equations of evaluation are developed to evaluate the effects of the structure and the properties on the cell performance, and the effectiveness of the developed equations is confirmed by a comparison of the results calculated by the equations with the model simulations. From these results, the structure of the porosity, the catalyst layer, and the polymer electrolyte thicknesses, that are optimum for the gas transport and proton conduction, are determined. It is found that the solubility of oxygen in the polymer is one of the dominant factors in the processes of the cathode catalyst layer, and that increasing the solubility is highly effective to reduce the need for platinum. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3624606] All rights reserved.
  • Ryosuke Ichikawa, Yutaka Tabe, Takemi Chikahisa
    POLYMER ELECTROLYTE FUEL CELLS 11 41 1 733 - 740 2011年 [査読有り][通常論文]
     
    In polymer electrolyte fuel cells (PEFCs), the freezing of produced water induces the extreme deterioration of the cell performance below zero. This phenomenon is serious problem in cold regions and is needed to be solved to achieve the practical use of PEFCs. In this study, we investigated the ice formation and the reaction rate in the cathode catalyst layer (CL) using a CRYO-SEM and a three-phase boundary model to clarify the freezing mechanism in the cold start at -20 degrees C. The observation results showed that the ice distribution formed in the CL is changed by the operation time and the current density. In particular, in a case of large current density, it was shown that ice grows from the membrane side to the gas diffusion layer (GDL) side. This process can also be analyzed in detail by the model that calculates the reaction rate in the CL.
  • K. Kadowaki, Y. Tabe, T. Chikahisa
    POLYMER ELECTROLYTE FUEL CELLS 11 41 1 431 - 438 2011年 [査読有り][通常論文]
     
    Micro-porous layers (MPLs) play an important role in the water management of polymer electrolyte fuel cells (PEFCs), but details of the mechanism to suppress water flooding has not been fully understood. In this study, we investigated water distribution at the interface between the MPL and the catalyst layer (CL) at the cathode side to clarify the effect of the MPL on discharge of produced water. Freezing method was applied to observe the distribution of the condensed water, and the ice distribution on the CL surface was quantified by a binary image processing. The effects of operation conditions on the water distribution were examined, and the distributions were also compared with large amount of ice on the CL surface after -10 degrees C cold start operation. It was shown from these results that the MPL has a role to prevent accumulation of water on the surface of CL and suppress water flooding.
  • Ben Salah Yasser, Yutaka Tabe, Takemi Chikahisa
    PROCEEDINGS OF THE ASME 8TH INTERNATIONAL CONFERENCE ON FUEL CELL SCIENCE, ENGINEERING, AND TECHNOLOGY 2010, VOL 1 1 541 - 547 2010年 [査読有り][通常論文]
     
    In a polymer electrolyte membrane (PEM) fuel cell, the condensed water in the gas channel prevents the supply of reactants to electrodes, which deteriorates the cell performance. The Lattice Boltzmann simulation has been conducted to understand the behavior of condensed water in the gas channels. The scheme of the two-phase flow with large density difference was applied to find the optimum gas channel design. The present simulation demonstrates the effect of the cross-sectional shape, the droplet initial position, droplet volume and the air flow velocity for a hydrophobic gas channel. Introducing a new dimensionless parameter, which is the pump work needed to remove the droplet from the gas channel, we investigate the effect of each parameter on the drain performance of a PEM fuel cell's gas channel.
  • Y. Tabe, S. Morioka, T. Nasu, T. Chikahisa
    POLYMER ELECTROLYTE FUEL CELLS 10, PTS 1 AND 2 33 1 1347 - 1353 2010年 [査読有り][通常論文]
     
    The porous separator has recently been proposed as an alternative to cells with gas flow channels in polymer electrolyte membrane fuel cells (PEFCs). In this study, basic characteristics of a PEFC with porous separator were identified using a cell for the direct observation of phenomena at the surface of porous separator and measurements of the local current density. The transport behavior of liquid water inside the porous separator was also investigated using another cell for the direct observation of the porous cross-section. Because of the higher contact resistance, the cell voltage with porous separator is lower than that with serpentine separator, but a stable operation can be maintained with the porous separator under conditions at higher current density and lower stoichiometric ratio of cathode gas. The cross-sectional observation showed that the porous separator is superior in the drainage performance from the surface of gas diffusion layer, and the hydrophilic property of porous separator is important for the better cell performance.
  • M. Nishino, Y. Tabe, T. Chikahisa
    POLYMER ELECTROLYTE FUEL CELLS 10, PTS 1 AND 2 33 1 1199 - 1206 2010年 [査読有り][通常論文]
     
    Because electron, proton, and oxygen are necessary for the cathode reaction in polymer electrolyte fuel cell, achieving the optimum structure of electrode catalyst layer and the efficient transport of the reactants is significantly effective to reduce the usage of Pt catalyst. In this study, we presented evaluation equations to investigate the relationship between the structure of cathode catalyst layer and the cell performance. The evaluation equations are based on the analysis using the three-phase boundary model by the authors, and can estimate the effects of cathode catalyst layer structures on the cell performance easily. This paper discusses optimum structure of the catalyst layer using these evaluation equations. Furthermore, the dominant parameter of the catalyst layer structure such as the amount of polymer electrolyte and the oxygen solubility in the polymer was confirmed experimentally.
  • 柏瀬 浩司, 田部 豊, 近久 武美
    年次大会講演論文集 2010 205 - 206 一般社団法人日本機械学会 2010年 
    This paper shows the experimental result of hydrogen generation efficiency by PEM electrolysis. The straight channel and titanium porous body were compared in performance. The following possibilities were shown by the experimental result: (1) The efficiency rises with increasing of temperature. (2) The porous body gave higher performance than the straight channel. (3) Cell performance deteriorated in repeating operation at relatively low current density, partially due to dry out.
  • シャハ リタンクマー, 大島 伸行, 田部 豊, 栗原 央流
    年次大会講演論文集 2010 197 - 198 一般社団法人日本機械学会 2010年 
    In this study, the deformation effect of gas diffusion layer (GDL) on the pressure drop of polymer electrolyte fuel cell (PEFC) separator channel has been investigated both numerically and experimentally. Gas channel and gas diffusion layers are regarded as two important parts of PEFC because they transport reactant gases to the catalyst layer and also byproduct from the catalyst layer. The deformation of GDL caused by the compression pressure plays an important role in the performance of PEFC since it affects the physical properties of the GDL, such as porosity, permeability and the cross sectional area of the gas channel. The flow behavior in the separator channel and GDL of PEFC has been investigated by using a transient, isothermal and three-dimensional numerical model. To develop the numerical simulation of PEFC, verification experiments and data acquisition of physical parameters were conducted by mechanical measurements.
  • Yutaka Tabe, Kazushige Kikuta, Takemi Chikahisa, Masaya Kozakai
    JOURNAL OF POWER SOURCES 193 2 416 - 424 2009年09月 [査読有り][通常論文]
     
    This paper investigates phenomena related to water condensation behavior inside a polymer electrolyte membrane fuel cell (PEMFC), and analyzes the effects of liquid water and gas flow on the performance of the fuel cell. A method for simultaneous measurements of the local current density across the reaction area and direct observation of the phenomena in the cell are developed. Experimental results comparing separator types indicate the effect of shortcut flow in the gas diffusion layer (GDL) under the land areas of serpentine separators, and also show the potential of straight channel separators to achieve a relatively uniform current density distribution. To evaluate shortcut flows under the land areas of serpentine separators. a simple circuit model of the gas flow is presented. The analysis shows that slight variations in oxygen concentration caused by the shortcut flows under the land areas affect the local and overall current density distributions. It is also shown that the establishment of gas paths under the water in channels filled with condensed water is effective for stable operation at low flow rates of air in the straight channels. (c) 2009 Elsevier B.V. All rights reserved.
  • Yutaka Tabe, Yongju Lee, Takemi Chikahisa, Masaya Kozakai
    JOURNAL OF POWER SOURCES 193 1 24 - 31 2009年08月 [査読有り][通常論文]
     
    Numerical simulations using the lattice Boltzmann method (LBM) are developed to elucidate the dynamic behavior of condensed water and gas flow in a polymer electrolyte membrane (PEM) fuel cell. Here, the calculation process of the LBM simulation is improved to extend the simulation to a porous medium like a gas diffusion layer (GDL), and a stable and reliable simulation of two-phase flow with large density differences in the porous medium is established. It is shown that dynamic capillary fingering can be simulated at low migration speeds of liquid water in a modified GDL. and the LBM simulation reported here,which considers the actual physical properties of the system, has significant advantages in evaluating phenomena affected by the interaction between liquid water and air flows. Two-phase flows with the interaction of the phases in the two-dimensional simulations are demonstrated. The simulation of water behavior in a gas flow channel with air flow and a simplified GDL shows that the wettability of the channel has a strong effect on the two-phase flow. The simulation of the porous separator also indicates the possibility of controlling two-phase distribution for better oxygen supply to the catalyst layer by gradient wettability design of the porous separator. (C) 2009 Elsevier B.V. All rights reserved.
  • Masataka Saito, Yutaka Tabe, Takemi Chikahisa
    PROTON EXCHANGE MEMBRANE FUEL CELLS 9 25 1 773 - 779 2009年 [査読有り][通常論文]
     
    In Polymer electrolyte membrane fuel cells (PEMFCs), the freezing of produced water induces the extreme deterioration of cell performance below zero. This phenomenon is serious problem in cold regions and is needed to be solved to achieve the practical use of PEMFC. In this study, we investigate ice distribution in the catalyst layer (CL) and in the gas diffusion layer (GDL) to clarify the freezing mechanism using an optical microscope and a CRYO-SEM. The observation result shows that the cold start at -10 degrees C makes ice at the interface between the CL and the micro porous layer of GDL. Little ice is, however, observed in the cold start at -20 degrees C, which indicates the ice formation in the CL. The CRYO-SEM observation is conducted at -20 degrees C to investigate the ice formation in the CL, and the result shows that this method is useful to clarify the ice distribution and the freezing mechanism.
  • Y. Tabe, H. Takamatsu, T. Chikahisa
    PROTON EXCHANGE MEMBRANE FUEL CELLS 9 25 1 39 - 47 2009年 [査読有り][通常論文]
     
    Because electron, proton, and oxygen are necessary for the cathode reaction in polymer electrolyte membrane fuel cells, achieving the optimum structure of electrode catalyst layer and the efficient transport of the reactants is significantly effective to reduce the usage of Pt catalyst. In this study, we develop a three-phase boundary and a cathode catalyst layer models to clarify structures appropriate for Pt high utilization, and the effects of the catalyst layer structures such as the porosity and the amount of polymer electrolyte, and the properties such as the oxygen solubility in the polymer are investigated using the models. From the calculation results, suitable structures, porosity and polymer electrolyte thickness, for gas diffusion and proton conduction are clarified. Further, it is presented that the solubility of oxygen in the polymer is one of the dominant factors and increasing in the solubility is extremely effective for reduction of the Pt usage.
  • 田部 豊, 李 勇往, ヤッサー ベンサラー, 近久 武美
    年次大会講演論文集 2009 133 - 134 一般社団法人日本機械学会 2009年 
    The simulation using the lattice Boltzmann method (LBM) has been developed to understand the behavior of liquid water and gas flow in porous media of PEM fuel cells. The original LBM code was parallelized and a increase in solving speed of the Poisson equation was made by the conjugate gradient (CG) method for the large-scale simulation. Some validation calculations were conducted and the rate of speeding up was verified. Using the parallelized LBM code with the CG method, the behavior of liquid water in a gas diffusion layer was simulated and the applicability of our code to two-phase simulation in a porous medium of PEM fuel cells are presented.
  • Yasser Ben Salah, Tabe Yutaka, Chikahisa Takemi
    年次大会講演論文集 2009 135 - 136 一般社団法人日本機械学会 2009年 
    Numerical simulations using the lattice Boltzmann method (LBM) are developed to elucidate the dynamic behavior of condensed water and gas flow in a polymer electrolyte membrane (PEM) fuel cell. Water management is essential to improve the performance of PEM fuel cells. Since it is difficult to investigate experimentally the liquid water behavior, we applied the lattice Boltzmann method for incompressible two-phase flow with large density difference and evaluate the liquid behavior in gas flow channels in a PEM fuel cell. In this paper, the effects of droplet position, air flow velocity and volume of liquid water droplet on the drain behavior and the efficiency were examined.
  • Yutaka Tabe, Daisuke Yoshida, Kazushige Kikuta, Takemi Chikahisa, Masaya Kozakai
    PROCEEDINGS OF THE 6TH INTERNATIONAL CONFERENCE ON FUEL CELL SCIENCE, ENGINEERING, AND TECHNOLOGY - 2008 821 - 828 2008年 [査読有り][通常論文]
     
    This paper investigated the effects of gas and liquid water flow on the performance of a polymer electrolyte membrane (PEM) fuel cell using cells to allow direct observation of the phenomena in the cell and measurements of the local current density and the local pressure loss. The experimental results to compare the separator type indicated the effect of cross-over flow in the gas diffusion layer (GDL) under the lands of serpentine separators on cell performance and the potential of straight channel separator to achieve a relatively-uniform current density distribution. To evaluate the crossover flow under the land of serpentine separators, a simple circuit model of the gas flow was developed. This analysis showed that slight variations in oxygen concentration caused by the cross-over flow under the land affect the local and overall current density distributions. It was also shown that the establishment of gas paths in the deep layer of GDL by the channels filled with condensed water is effective for stable operation at low flow rates of air in the straight channels.
  • 柏瀬 浩司, 菊田 和重, 田部 豊, 近久 武美
    年次大会講演論文集 2008 53 - 54 一般社団法人日本機械学会 2008年 
    Experiment and numerical simulation indicated that the large NOx formation in diesel engine is due to the weak mixing intensity in the spray tip region, where the flow and turbulence structure is quite different from the continuous jet flames. The fact indicates that there is a possibility of reducing NOx from diesel engines by enhancing mixing intensity at the spray tip region to the level of continuous jet flame. This paper presents the analysis of NOx formation in diesel engines using HTB-DECS to confirm the effect of pre-shock jet. This analysis performed by changing the magnitude and/or timing of the turbulence that influences the air entrainment into the fuel-spray. The results show that NOx formation is greatly related in the turbulence strength. It is very important to control the timing to give the strong turbulence. Furthermore, the simulation also performed by the jet flame with/without the impinging jet using FLUENT. The large NOx reduction was able to be confirmed in the case with the impinging jet.
  • 高松 宏行, 田部 豊, 菊田 和重, 近久 武美
    年次大会講演論文集 2008 25 - 26 一般社団法人日本機械学会 2008年 
    To decrease the usage of the Pt catalyst in polymer electrolyte membrane fuel cell (PEMFC), optimization of catalyst layer structure and three-phase zone is one of key issues. In this study, numerical simulation was conducted to investigate the relation between the structure of cathode catalyst layer and cell performance (over voltage and current density). From the calculation results, suitable structures, porosity and polymer electrolyte thickness, for gas diffusion and proton conduction were clarified.
  • Yutaka Tabe, Takemi Chikahisa
    SAE Technical Papers 834 - 839 2007年 [査読有り][通常論文]
     
    This paper investigates the effect of enhancing mixing of spray tip region on NOx reduction from diesel engines. The concept is based on the fact that dominant part of NOx formation is the flame tip region with weak mixing intensity. Two methods to realize our concept were attempted in a constant volume combustion bomb and in an actual diesel engine. One is the two-stage injection and another is the method with a jet created by combustion of premixed charge in a turbulence cell. The paper presents results of variety trials of experiment, and it discusses necessary means to achieve the concept. Copyright © 2007 Society of Automotive Engineers of Japan, Inc.
  • Yutaka Tabe, Kohsuke Kibo, Kazushige Kikuta, Takemi Chikahisa, Masaya Kozakai
    PROCEEDINGS OF THE ASME/JSME THERMAL ENGINEERING SUMMER HEAT TRANSFER CONFERENCE 2007, VOL 2 2 55 - 61 2007年 [査読有り][通常論文]
     
    In a polymer electrolyte membrane (PEM) fuel cell, the condensed water in the separator-channel prevents the supply of reactants to electrodes, which deteriorates the cell performance. The Lattice Boltzmann simulation has been developed to understand the behavior of condensed water in the separator-channels. The calculation process was improved, and the effect on the stability and reliability of simulation of two-phase flows with large density difference was confirmed. Further, the comparison with experiment of the falling water droplet by gravitation on the slope of micro porous layer was conducted to validate effectiveness of the improved simulation. It was shown that the simulation can express the increase in falling speed of water droplet and the effect of inclined angle of the slope, and our simulation is effective enough to estimate the liquid water and air flow in the separator-channel. Finally, the simulation of liquid water behaviors in separator-channels with various cross-sectional shapes was conducted, and the drain efficiency of water droplet of separator-channel was discussed.
  • Yutaka Tabe, Sang-Kyun Park, Kazushige Kikuta, Takemi Chikahisa, Yukio Hishinuma
    JOURNAL OF POWER SOURCES 162 1 58 - 65 2006年11月 [査読有り][通常論文]
     
    The performance of free-breathing polymer electrolyte membrane fuel cells (PEMFCs) was studied experimentally and the effect of the cathode separator structure on the cell performance was investigated. Two types of cathode separators were used for a cell with an 18 cm(2) active area: an open type with parallel rectangular open-slits and a channel type with straight vertical channels with open ends. The polarization curves, cell impedance, and contact pressure distribution of the separators were measured with each type of cathode structure. The result showed that it is difficult to realize a uniform contact pressure across the cell layers for the open type separator, and this results in higher contact resistance and poorer cell performance than the channel type separator. The channel type separator can maintain a low contact resistance, and the cell performance is strongly affected by the natural convection inside the channel. Optimization of the channel design of the channel type separator achieves good performance and this type of separator is superior for a free-breathing PEMFC. A computational three-dimensional analysis for the free-breathing channel type PEMFC with the different channel depths was performed, and it identified the influence of natural convection. (c) 2006 Elsevier B.V. All rights reserved.
  • 岩佐 能孝, 川上 佳, 田部 豊, 近久 武美
    日本機械学會論文集. B編 72 714 469 - 476 一般社団法人日本機械学会 2006年02月 [査読有り][通常論文]
     
    This paper presents mapping method to show characteristics of cogeneration systems (CGS) for the reduction of carbon dioxide emission and economy. In this mapping method, effects of CGS can be consolidated into rated reduction ratio, relative reduction ratio map, demand repetition map and weight map. These are without recourse to building size or installed capacity. By lapping these maps, it can be easy to evaluate compatibility with each building types and optimal installed capacity. Variation of effects of CGS for different conditions can be evaluated visually from variation of maps. Anal...
  • Takemi Chikahisa, Yutaka Tabe, Kazushige Kikuta, Naofumi Nohara, Hideki Shinohara
    Proceedings of the 4th International Conference on Fuel Cell Science, Engineering, and Technology, Pts A and B 2006 25 - 30 2006年 [査読有り][通常論文]
     
    This paper observes phenomena related to water production behavior inside a fuel cell and analyzes the effect on the current and temperature distribution across the reaction area. A fuel cell permitting direct observation of the phenomena in the cell, 2-D temperature measurements in the cathode channels, and local current density measurements on the anode side was manufactured. The experimental results showed the production and flow of liquid water in the cell, and there were good correlations among the distributions of current density, temperature, and water amounts in the channels. The behavior of current, voltage, water distribution, and pressure differences in the cathode channels were used to hypothesize about the possibility of gas paths deep in the gas diffusion layer in the flooded condition and a positive feedback mechanism in the drying-out condition.
  • STUDY ON FREEZING PHENOMENA IN PEM FUEL CELL BELOW FREEZING
    Tabe, Y, Nakamiya, H, Kikuta, K, Chikahisa, T, Kagami, F, Yoshizawa, K
    Proceedings of 13th International Heat Transfer Conference 2006年 [査読有り][通常論文]
  • 田部 豊, 岩佐 能孝, 近久 武美
    年次大会講演論文集 2006 173 - 174 一般社団法人日本機械学会 2006年 
    This paper analyzes primary energy reduction effect of cogeneration system (CGS) installed at individual house with large demand fluctuation, and discusses its improved system. The start-stop operation considering the start-up energy of CGS and heat radiation of thermal storage unit was proposed as a better operation method of CGS installed at individual house. It was shown from the analysis using the actual energy demand pattern of six houses that the start-stop operation is available and electricity network has mitigation effect of large demand fluctuation to increase the primary energy reduction. In order to elucidate the effective improved system, the reduction target was estimated from the analysis using ideal values for power interchange, heat radiation of thermal storage unit, and partial load efficiency of CGS.
  • 大津 翔, 田部 豊, 近久 武美
    年次大会講演論文集 2006 249 - 250 一般社団法人日本機械学会 2006年 
    This paper presents results of two different trials to reduce NO_x from diesel engines: one is pre-shock injection method and the other is the method with pre-shock jet created by using premixed charge combustion. The both concepts are based on the fact that dominant part of NO_x formation is the area close to the spray tip, where mixing intensity is weak. The mixing intensity of this area is to be maintained high by the two methods. The result shows reasonable effect for the reduction of NO_x, but the extent was not as significant as expected. It was found that the pre-shock jet was not realized in the present setup, and further attempt was necessary to evaluate the concept.
  • 岩佐 能孝, 田部 豊, 近久 武美
    空気調和・衛生工学会論文集 0 104 19 - 27 社団法人空気調和・衛生工学会 2005年11月 [査読有り][通常論文]
     
    本研究では,炭酸ガス削減効果を最大としながら系統にとっても負荷平準化効果を持つ分散協調型コジェネレーションネットワークシステム(CGNS)を提案し,その炭酸ガス削減効果ならびに系統電力負荷変動に対する影響について解析を行った.その結果,系統ネットワークを利用していない現状のコジェネレーションシステムに比べて大幅に炭酸ガス削減効果を増大させることができ,しかも系統負荷平準化のポテンシャルを有することが確認された.エネルギー供給会社間の協調を実現し,さらに熱電比の関係で普及の進まないコジェネレーションの導入を促進する上で,有用な社会エネルギーシステムになり得るものと考えられる.
  • Yutaka Tabe, Takamichi Ochi, Kazushige Kikuta, Takemi Chikahisa, Hideki Shinohara
    Proceedings of the 3rd International Conference on Fuel Cell Science, Engineering, and Technology 87 - 92 2005年 [査読有り][通常論文]
     
    In a polymer electrolyte membrane fuel cell, the condensed water in the separator-channel prevents the supply of reactants to electrodes, which deteriorates the cell performance. The Lattice Boltzmann simulation has been conducted to understand the behavior of condensed water in the separator-channels. The scheme for the two-phase flow with large density difference was applied and the boundary condition for wettability at the corner inside the channel was examined. The present simulation demonstrates the effects of the cross-sectional shape, the wettability of channel and the volume of condensed water on the liquid water behavior. In the hydrophilic separator-channels, the liquid water spreads along the channel wall to form film and, in a specific condition, the water draws away from the gas diffusion layer, which suppresses the flooding. On the other hand, the liquid water forms sphere, covering larger area of the surface of gas diffusion layer in the hydrophobic separator-channels, but the drain performance of liquid water is superior.
  • 中宮 弘満, 菊田 和重, 田部 豊, 近久 武美, 各務 文雄, 吉澤 幸大
    年次大会講演論文集 2005 275 - 276 一般社団法人日本機械学会 2005年 
    In PEFC at low temperature, the freezing of produced water induces the extreme deterioration of cell performance. The characteristics of start-up below freezing in a wide variety of current densities was investigated and the cell impedance measurements was conducted to clarify the freezing phenomenon in PEFC. It was confirmed that the characteristics can be related to the amount of produced water and the rise in cell temperature by reaction. It was also showed that increase of reaction resistance, which was considered to be mainly due to increase gas transfer resistance, has much effect on freezing phenomenon.
  • 野原 尚史, 菊田 和重, 田部 豊, 近久 武美
    年次大会講演論文集 2005 273 - 274 一般社団法人日本機械学会 2005年 
    A fuel cell was made to allow direct observation of the phenomena in the cell, 2-D temperature measurement in cathode channels, and local current density measurements in anode side. The experimental results showed good correlation among direct view in the cell, temperature distribution and local current density. The experiment indicates transition phenomena of dry out and flooding depending on the flow and current conditions. The results suggests the possibility of different current density distribution for the same experimental conditions depending on the previous MEA condition history.
  • S Hirai, R Takamatsu, Y Tabe, K Suzuki, K Okazaki
    GREENHOUSE GAS CONTROL TECHNOLOGIES 481 - 486 2001年 [査読有り][通常論文]
     
    Since CO2 dissolves in the process of droplets rising upward due to buoyancy in the seawater at intermediate ocean depth, concentration of dissolved CO2 is strongly influenced by the initial droplet size. The present paper describes an experimental elucidation that the released droplet size is prescribed by not only the injection rate and nozzle diameter but also growth and deformation of hydrate thin film whose characteristics differs due to temperature conditions. It is also reported that the high deformation rate causes hydrate film rupture that depends on the temperature condition.
  • Y Tabe, S Hirai, K Okazaki
    JOURNAL OF CRYSTAL GROWTH 220 1-2 180 - 184 2000年11月 [査読有り][通常論文]
     
    Massive hydrate growth, which produced large amounts of hydrate without continual agitation as compared with the thin hydrate film that seals the interface between water and guest phases, was investigated, We found that materials with surface-free energies having large polar components promoted massive hydrate growth in the CO2-water system; conversely materials with Small polar components, such as polymers, had only the hydrate him formation, (C) 2000 Elsevier Science B.V. All rights reserved.
  • Y Tabe, S Hirai, K Okazaki
    JOURNAL OF CHEMICAL ENGINEERING OF JAPAN 33 4 612 - 616 2000年08月 [査読有り][通常論文]
     
    Dissolving CO2 into the ocean by the pumping of liquid CO2 is a strategy to offset the buildup of atmospheric CO2 However, under the high-pressure, low-temperature conditions in the deep ocean a CO2 hydrate film quickly isolates the liquid CO2 from seawater thus: suppressing dissolution. The thickness of the hydrate film is one of the most important parameters for understanding the mass transport mechanism through the hydrate film during the liquid CO2 dissolution. We suggest a new method for measuring the thickness of the hydrate film formed at the interface between the liquid CO2 and flowing water. Our method assumes that a unique thickness of hydrate film is kept through hydrate dissolution and growth at the water-, and Liquid CO2-hydrate interfaces, respectively. When growth stops, the net dissolution allows estimation of the original hydrate thickness. Under the conditions of our experiment, the CO2 hydrate film thickness is about 0.4 mu m.
  • Lateral Growth Rates of CO2 Clathrate-hydrate Film
    S. Hirai, Y. Tabe, S. Kamijo, K. Okazaki
    Thermal Science & Engineerin 8 5 1 - 6 2000年 [査読有り][通常論文]
  • S Hirai, Y Tabe, K Kuwano, K Ogawa, K Okazaki
    GAS HYDRATES: CHALLENGES FOR THE FUTURE 912 246 - 253 2000年 [査読有り][通常論文]
     
    MRI measurements of hydrate thickness growth have been measured and this phenomenon applied to advanced CO2 ocean dissolution technology. CO2 droplets dissolve during the process of sinking from their release point into deep ocean, by forming fine hydrate particles inside CO2 droplets before the droplets are released from a towed pipe on a moving ship. This results in a sufficiently long sequestration period from the atmosphere and further reduces biological impact. The increasing rate of hydrate film thickness in forming hydrate particles was measured by an ultrahigh-pressure magnetic resonance imaging (MRI) technique.
  • S Hirai, Y Tabe, G Tanaka, K Okazaki
    GREENHOUSE GAS CONTROL TECHNOLOGIES 317 - 322 1999年 [査読有り][通常論文]
     
    Among various CO2 ocean sequestration technologies, measures to restrict the increase of atmospheric CO2 concentration, releasing CO2 droplets from towed pipe of ship reduces biological impact hy the dilution of dissolved CO2 due to the motion of moving ship. CO2 droplets. released around 1500m ocean depth. rise upward due to buoyancy and dissolved CO2 at the sea depth of 500-1500m is considered to outgas to the atmosphere in 20-100 years. Here, we present a new concept of CO2 sequestration in the ocean that CO2 would dissolve at the sea depth deeper than the release point (i.e.. 1500m) and biological impact would be minimized. Before releasing CO2 droplets from the tip of towed pipe of moving ship. hydrate fine particles are formed by injecting water small droplets inside CO2 droplets. Since density of hydrate is 1.1 g/cm(3), CO2 droplets including hydrate Fine particles more than 40 vol% sink downward from release point into deep ocean that result in longer term sequestration. In addition, since depth of ocean is 4000m on an average, long travel distance for CO2 droplets dissolution enables diluted CO2 dissolution, pH profiles in most of the part of sea depth would be larger than 7.0, where biological impact would be minimized. The present concept is verified by an experiment.
  • Y Tabe, S Hirai, K Okazaki
    GREENHOUSE GAS CONTROL TECHNOLOGIES 311 - 315 1999年 [査読有り][通常論文]
     
    Liquid CO2 dissolution observed at CO2 sequestration in the ocean, CO2 mitigation strategy, is accompanied by CO2 clathrate-hydrate film, which has a large effect on the estimation of the strategy. Therefore, the mechanism of CO2 dissolution with hydrate film is a point of special interest. From this viewpoint, the present paper presents a new technique to measuring the thickness of the hydrate film formed at the interface between liquid CO2 and water. The technique is based on the dissolution model of liquid CO2 with hydrate film whose unique thickness is maintained by the dissolution at the water side and formation at the liquid CO2 side in the process of CO2 dissolution, if the hydrate is not formed at the liquid CO2 side, only the dissolution occurs and its characteristics is applied to the measurement of the thickness of hydrate film. Using a high pressure experiment apparatus, a water droplet was injected into the liquid CO2 to attach the hydrate film, The water droplet has an effect to stop the hydrate formation. After 2.1 s, the hydrate film disappeared at the contact point. The hydrate thickness was estimated to be about 0.43 mu m using these data. it was confirmed that the experimental results also have supported the dissolution model.
  • 田部 豊, 平井 秀一郎, 岡崎 健, 河村 雄行, 土方 邦夫
    日本機械学會論文集. B編 64 623 2189 - 2195 一般社団法人日本機械学会 1998年07月 [査読有り][通常論文]
     
    Dissolution of liquid CO_2 accompanied by CO_2 clathrate-hydrate film into sea water is observed at CO_2 sequestration in ocean, which is considered to be an effective strategy of CO_2 mitigation. The dissolution mechanism was experimentally investigated by considering the relation between measured CO_2 surface concentration of hydrate-covered CO_2 droplets and CO_2 solubility. It was made clear that, in the temperature range of hydrate formation, the measured surface concentration decreases with the decrease of temperature and it exactly corresponds to CO_2 solubility. This fact indicates ...
  • Y Tabe, S Hirai, K Okazaki, K Kawamura, K Hijikata
    HEAT TRANSFER 1998, VOL 5 75 - 80 1998年 [査読有り][通常論文]
     
    Dissolution of liquid CO2 accompanied by CO2 clathrate-hydrate film into sea water is observed at CO2 sequestration in ocean, which is considered to be an effective strategy of CO2 mitigation. The dissolution mechanism was experimentally investigated. It was made clear that, in the temperature range of hydrate formation, the measured surface concentration of a hydrate-covered CO2 droplet decreases with decreasing temperature and agrees well with the CO2 solubility. This fact indicates that the dissolution rate of a CO2 droplet with hydrate film is controlled by the mass transfer rate of dissolved CO2 at the droplet surface into water and the decrease of the dissolution rate due to hydrate can be explained by the decrease of CO2 solubility in the hydrate formation region. Further, in order to clarify the decreasing mechanism of CO2 solubility, a thermodynamic method was employed. The CO2 solubility was estimated from the relationship between the molar Gibbs free energy of water-liquid CO2 mixture and that of hydrate and it has shown that the present method could predict the decrease of CO2 solubility in the hydrate formation region fairly well.
  • S Hirai, K Okazaki, H Yazawa, H Ito, Y Tabe, K Hijikata
    ENERGY 22 2-3 363 - 367 1997年02月 [査読有り][通常論文]
     
    This paper deals with estimation of the diffusion coefficient in an H2O-CO2 system under high pressure and the use of laser-induced fluorescence (LIF) for measuring CO2 dissolution. A liquid CO2 droplet without CO2 clathrate was placed in the flow where the velocity profile is uniform. The diffusion coefficient is estimated by measuring the liquid CO2 droplet-dissolution rate and using the empirical mass transfer coefficient. The measured diffusion coefficient agrees well with the Wilke-Chang equation at pressures of 29.4 and 39.2 MPa. We have used LIF for measurement of the large non-uniform, two-dimensional pH distribution induced by CO2 dissolution. A sheet laser beam was provided by a YAG laser and the two-dimensional LIF intensity was detected by an image-intensified CCD diode-array camera. Copyright (C) 1996 Elsevier Science Ltd.
  • S Hirai, K Okazaki, Y Tabe, K Hijikata, Y Mori
    ENERGY 22 2-3 285 - 293 1997年02月 [査読有り][通常論文]
     
    The dissolution rate of liquid in CO2 in seawater, when a CO2 clathrate-hydrate film exists at the interface, is a key factor for estimation of CO2 sequestration in ocean and marine environmental impact assessment. Liquid CO2 dissolution phenomena in CO2 sequestration in the ocean include (i) dissolution and diffusion of liquid CO2 droplets at intermediate sea depths and (ii) CO2 dissolution in undercurrent flows from a liquid CO2 pool at seabeds deeper than 3000 m. For the first case, the present paper presents a data base of clathrate-hydrate covered CO2 droplet surface concentration, which is essential for an analysis of CO2 droplet dissolution behavior. Effects of pressure and temperature are included. A numerical simulation for dissolving liquid CO2 droplets released at an intermediate ocean depth is presented. The effects of released droplet size and ambient CO2 concentration on dissolution behavior are clarified. For the second case, an experiment simulating dissolution of liquid CO2 stared at a seabed into an undercurrent flow was conducted. The pool surface was covered with clathrate and the surface concentration of the clathrate-covered CO2 pool was estimated. Applying the measured surface concentration and mass transfer coefficient obtained from the actual conditions of deep ocean data, the time scale of CO2 dissolution into an undercurrent how was estimated, which is important for estimation of CO2 disposal in the deep ocean. Copyright (C) 1996 Elsevier Science Ltd.
  • S Hirai, K Okazaki, Y Tabe, K Hijikata
    ENERGY CONVERSION AND MANAGEMENT 38 S313 - S318 1997年 [査読有り][通常論文]
     
    Dissolution of liquid CO2 droplets at intermediate depth of ocean is strongly effected by the release methods of liquid CO2 and hydrate formation. The present paper presents numerical simulations for the dissolution behavior of CO2 droplets released from (1) pipeline outlet which is a fixed point at intermediate ocean depth and (2) pipe of moving ship. Clathrate-hydrate formation on the CO2 droplet surface was fully included for both cases (1) and (2). External flow conditions around the CO2 droplets are different between (1) and (2). A rising plume water flow is formed for case (1) and a free stream turbulence induced by the wake behind the pipe is for case (2). It was indicated that, for case (1), the released droplet diameter is required to be controlled to be less than 0.8cm to obtain the complete dissolution for the travel distance less than 1000m. The large travel distance is caused by the rising motion of plume water flow. Even if the CO2 is released from 16 separated branches, the travel distance is reduced to 30%. In addition, increase of ambient CO2 concentration drastically decreases the dissolution. On the other hand, for case (2), it was demonstrated that easier released droplet size condition to obtain complete dissolution is acceptable when liquid CO2 is released from a pipe of moving ship, which also possesses a high potential that the ambient CO2 concentration would not increase. (C) 1997 Elsevier Science Ltd.
  • S Hirai, K Okazaki, Y Tabe, K Hijikata
    WASTE MANAGEMENT 17 5-6 353 - 360 1997年 [査読有り][通常論文]
     
    Present paper reports dissolution rate of liquid CO2 with hydrate film into water which is essential for estimation of CO2 sequestration in ocean and marine environmental impact assessment. Effect of hydrate film was fully included in the simulations. Droplet diameter released from pipeline introduced from power-plant is required to be less than 0.8 cm to obtain the complete dissolution for the travel distance less than 1000 m. On the other hand, it was demonstrated that easier released droplet size condition to obtain complete dissolution is acceptable when liquid CO2 is released from a pipe of moving ship. For CO2 isolation at seabeds deeper than 3000 m, an experiment simulating dissolution of liquid CO2 stored at a seabed into an undercurrent flow was conducted. Applying the measured surface concentration and mass transfer coefficient obtained from the actual conditions of deep ocean, the time scale of CO2 dissolution into an undercurrent flow was estimated to be around 240 years for a complete dissolution of the CO2 pool created by a 1 GW power plant in 10 years. (C) 1998 Elsevier Science Ltd. All rights reserved.
  • S Hirai, K Okazaki, Y Tabe, K Kawamura
    ENERGY CONVERSION AND MANAGEMENT 38 S301 - S306 1997年 [査読有り][通常論文]
     
    Molecular dynamics simulation has been conducted in order to obtain the fundamental understanding for the formation mechanism of CO2 clathrate-hydrate that suppresses the dissolution of liquid CO2 isolated at deep ocean floor. It was demonstrated that the H2O molecules formed a characteristic cage structure of type I clathrate around the CO2 guest molecules after 260 ps from the initial condition of H2O molecules at pressurized water state. CO2 clathrate-hydrate formation kinetics has elucidated that the interactions between the CO2 guest molecules would form a low potential region, which has an effect to suppress the H2O molecules motions in a two-dimensional plane and assist to form cage structures consisted of 5 and 6 membered rings. (C) 1997 Elsevier Science Ltd.

書籍

  • マイクロ・ナノ熱工学の進展
    田部 豊, 境田 悟志 (担当:共著範囲:第2編 第12章 第2節,PP.368-373)
    エヌ・ティー・エス 2021年05月
  • Micro & Nano-Engineering of Fuel Cells
    T. Chikahisa, Y. Tabe (担当:共著範囲:Section 1: Pore-scale water transport investigation for polymer electrolyte membrane (PEM) fuel cells, PP.1-35)
    CRC Press 2015年

講演・口頭発表等

その他活動・業績

  • 田部豊, 近久武美 伝熱 57 (240) 43‐50 2018年07月01日 [査読無し][通常論文]
  • Kengo Suzuki, Naoya Takahashi, Yutaka Tabe, Takemi Chikahisa 2017 INTERNATIONAL CONFERENCE ON GREEN ENERGY AND APPLICATIONS (ICGEA 2017) 90 -94 2017年 [査読無し][通常論文]
     
    This study focuses on the power supply system of Hokkaido, the largest and northernmost prefecture in Japan and identifies the barriers to raise the share of wind and solar power to 100%. An increase in total system cost versus the penetration of wind and solar power into the energy system was examined based on the current technology and cost level. The effect of cost reductions in solar power and batteries are also investigated. The results show that the share of wind and solar power can be raised to 50% without significant increase in the total system cost. To achieve this, wind power should mainly be installed in the northern area and transmission lines should be enhanced to connect the northern and capital areas. However, the profitability of non-renewable power decreases with increasing wind power capacity. As the share of renewables exceeds 50%, the total system cost rapidly increases because of a widening of the demand-supply gap. Reducing the cost of solar power can reduce the total system cost to some extent. However, the main power source is still wind energy because the seasonal pattern of wind power output is in higher correlation with demand than solar power.
  • 赤澤 眞之, 鈴木 研悟, 田部 豊, 近久 武美 年次大会 : Mechanical Engineering Congress, Japan 2015 "S0830302 -1"-"S0830302-5" 2015年09月13日 
    The authors proposed the concept that CHPs, which is combined heat and power and sometimes called co-generation, are installed to buildings with large heat demand and excessively generated electricity is consumed in buildings in the grid network. The analysis demonstrated significant effect of the system for the reduction of CO_2 with keeping cost advantage, compared to the non-networked CHPs. This paper analyses dependence of the effect on regions, CHP devices, and cost conditions. The results show that the networked CHP system keeps its significant effect even in Tokyo area, although the effect is larger in Sapporo. Compared to the non-networked system, CO_2 can be reduced twice by the networked CHPs. This is due to the fact that houses have high heat/electricity demand ratio even in Tokyo. The paper also shows the effectiveness of fuel cell CHPs compared to gas-engines, due to higher efficiency of electric generation. Cost analysis indicates that the supply unit cost ratio of grid electricity and town gas linearly influences the cost benefit of CHPs.
  • 東 武志, 鈴木 研悟, 田部 豊, 近久 武美 年次大会 : Mechanical Engineering Congress, Japan 2015 "J0560101 -1"-"J0560101-3" 2015年09月13日 
    In PEFC, flooding phenomena is one of the critical problems to be solved. Therefore, it is necessary to optimize water and reactant gas flow management in the cell. Our research group applied the lattice Boltzmann method (LBM) for the two phase flow with high density ratio, including the effect of wettability, and has carried out the analyses of gas and liquid water flow to propose the gas diffusion layer (GDL) with the high water draining capability. In this study, we simulated liquid water behavior inside of the GDL applying the equal density LBM in order to achieve shorter computational time comparing to the high density ratio LBM. In the equal density LBM code developed by the authors, we found two problems. One was a decrease in amount of water in the GDL, and the other was discriminating liquid water behavior compared with in the high density ratio LBM. This paper explains the applied improvements to solve these two problems by setting the wall boundary conditions appropriately.
  • 八重原 幹樹, 鈴木 研悟, 田部 豊, 近久 武美 年次大会 : Mechanical Engineering Congress, Japan 2015 "J0560103 -1"-"J0560103-3" 2015年09月13日 
    According to earlier studies, the porous flow fields of Polymer Electrode Fuel Cell (PEFC) are more tolerant against flooding phenomenon in comparison with conventional flow channels such as straight and serpentine type channels. However, the relationship between the porous structure and water management ability of porous media has not been clarified. This study investigated the influence of porosity and pore diameter of metal foam flow fields on the cell performance and water transport. Celmets, which are the porous media with foam structure and high porosity in comparison with sintered metal, is used as the porous flow fields. The results show that the influence of pore diameter on cell performance and water drainage is small under the condition of this study. And the usage of celmets with higher porosity, 96.8%, causes a decrease in cell performance. Such a performance decrease appears to be caused by the lower contact pressure and inferior gas diffusion.
  • 柳 雄祐, 鈴木 研悟, 田部 豊, 近久 武美 動力・エネルギー技術の最前線講演論文集 : シンポジウム 2015 (20) 335 -336 2015年06月07日 
    This study analyzes an influence of CO_2 reduction target on the energy mix and energy supply cost of Hokkaido until the 2050. As the target becomes more aggressive, the energy supply cost increases mainly in the power generation sector, and the increase in power generation cost is mainly caused by the substitution of fossil fuel fired power with wind power. When the larger amount of wind power is installed, the mismatch between demand and supply increases mainly in the summer and interphase, and the larger amount of surplus electricity need to be discarded.
  • 嶋田 遼, 内山 真理, 鈴木 研悟, 田部 豊, 近久 武美 動力・エネルギー技術の最前線講演論文集 : シンポジウム 2015 (20) 75 -76 2015年06月07日 
    In vanadium redox flow battery, energy efficiency decreases mainly because of ohmic loss IR_ and concentration overpotential η_. Especially capacity loss by early shutdown timing of charge and discharge process is strongly affected by η_, which depends on mass transfer of active species to reaction area. In this study, we conducted charge-discharge experiments with a single cell battery in order to investigate the behavior of cell voltage around shutdown and elucidate the relationship between mass transfer coefficient k and electrolyte flow condition. It was shown that that the k is proportional to 0.5〜0.6th power of mean electrolyte flow velocity ν, and the coefficients are different for the charge and discharge processes.
  • 石間 裕太, 鈴木 研悟, 田部 豊, 近久 武美 動力・エネルギー技術の最前線講演論文集 : シンポジウム 2015 (20) 101 -102 2015年06月07日 
    At cold startup of a polymer electrolyte fuel cell PEFC at -10 ℃, the produced water remains as supercooled water before it freezes, and then the shutdown occurs with ice layer formation between the cathode catalyst layer (CL) and micro-porous layer (MPL). This study investigated ice formation behavior during the cold startup with supercooled water in PEFC by measurements of cold start characteristic and observations of the cathode CL using a Cryo-SEM. The ice layer observed at the interface became thicker gradually during the startup, and this suggested that the produced water moves through ionomer in the CL. Basic investigation of the water transport through the ionomer and its driving force was conducted, and introduction of a hydrophilic MPL was tested to improve the cold start characteristics, longer startup period.
  • Jia-ming Gong, Nobuyuki Oshima, Yutaka Tabe PROCEEDINGS OF THE ASME 13TH INTERNATIONAL CONFERENCE ON NANOCHANNELS, MICROCHANNELS, AND MINICHANNELS, 2015 2015年 [査読無し][通常論文]
     
    The free energy based lattice Boltzmann method (LBM) for two-phase flow with large density ratio is used to simulate droplet dynamics in the polymer electrolyte fuel cell (PEFC). The shape deformation of a static water droplet in the gas channel occurred in the simulations was eliminated. In this LBM model, two types of staggered grids which respectively make use of the velocity components from the orthogonal and diagonal directions are blended to calculate the hydrodynamic pressure from the Poisson equation, with the successive over relaxation method (SOR). It is found that the simulated water droplet shape is determined by both the blending factor of the two types of staggered grids and the radius length. The appropriate blending factor for each radius length is summarized to optimize the simulation. The dependence of shape deformation on the blending factor and the radius length is further validated while considering the wettability effect of the solid wall of the gas channel. It is proved that the summarized appropriate blending factors are still practical when the concept of equivalent radius length is adopted.
  • Takemi Chikahisa, Yutaka Tabe Micro and Nano-Engineering of Fuel Cells 1 -36 2015年01月01日 [査読無し][通常論文]
     
    © 2015 Taylor & Francis Group, London, UK. Polymer electrolyte membrane (PEM) fuel cells could potentially become promising power sources for vehicles and stationery combined heat and power (CHP) generators in the near future, as they have higher efficiency and cleaner emission characteristics than conventional engines. Although hydrogen fuel for the cells is mainly produced from natural gas with a conversion efficiency of around 75% at present, well-to-wheel efficiency is still superior to conventional engines. When hydrogen is produced from renewable energy sources, such as solar cells and windmills, PEM fuel cells will be the most powerful devices to convert hydrogen into power with the highest efficiency.
  • 八重原 幹樹, 鈴木 研悟, 田部 豊, 近久 武美 北海道支部講演会講演概要集 2014 (53) 75 -76 2014年09月27日
  • 西川 浩至, 鈴木 研悟, 田部 豊, 近久 武美 北海道支部講演会講演概要集 2014 (53) 73 -74 2014年09月27日
  • 嶋田 遼, 鈴木 研悟, 田部 豊, 近久 武美 北海道支部講演会講演概要集 2014 (53) 77 -78 2014年09月27日
  • 柳 雄祐, 鈴木 研悟, 田部 豊, 近久 武美 北海道支部講演会講演概要集 2014 (53) 93 -94 2014年09月27日
  • 高城 広輔, 鈴木 研悟, 田部 豊, 近久 武美 年次大会 : Mechanical Engineering Congress, Japan 2014 "J0610103 -1"-"J0610103-4" 2014年09月07日 
    As a smaller and lighter hydrogen PEFC, we adopted "Dead-end mode" and "Open-cathode" systems. Previous study showed that dry-out and anode flooding deteriorate the cell performance under drier air and higher current density conditions. In this paper, the effective methods to prevent dry-out and anode flooding were investigated experimentally using a single cell simulating the temperature distribution in a PEFC stack. It was shown that, in the condition that dry-out is caused easily by large increase in the cell temperature, the higher flow rate of the cathode air with low humidity improves cooling capacity, but also makes the MEA drier, resulting in dry-out. This means that it is difficult to suppress the dry-out by the control of the cathode air and other cooling method is needed. The results of experiment introducing a cooling channel showed that the control of the cooling air through the cooling channel is effective for suppressing the dry-out, and the control of the cathode air is also effective for suppressing the anode flooding.
  • Jiaming GONG, 大島 伸行, 田部 豊 年次大会 : Mechanical Engineering Congress, Japan 2014 "G0110103 -1"-"G0110103-5" 2014年09月07日 
    The effect of 0-velocity inlet and free-out outlet boundary condition used in the free energy based LBM with large density ratio was investigated in this paper. A static water droplet in the quiescent gas in a gas channel was simulated with both the 0-velocity inlet and free-out outlet boundary condition and the periodic boundary conditions along Z direction of the computational domain. The total mass loss was observed while using the 0-velocity and free-out outlet boundary condition. By comparing with results from the periodic boundary condition, it was proved that both the velocity inlet and the free-out outlet can be the sources of mass un-conservation; the difference of the simulation results between the two types of boundary conditions are small, both boundary conditions can be used in the target simulation.
  • 石間 裕太, 鈴木 研悟, 田部 豊, 近久 武美 動力・エネルギー技術の最前線講演論文集 : シンポジウム 2014 (19) 279 -280 2014年06月25日 
    In polymer electrolyte fuel cells (PEFCs), the produced ice below freezing temperature has the potential to adversely affect the structure of cathode catalyst layer (CL) and the cell performance. This study investigated degradation characteristics of a PEFC resulting from produced ice in CL. To repeat cold start in a short time, we introduce N_2 purge to remove the produced ice below freezing temperature. The cycle of cold start at -10℃ makes the cell performance gradually-degraded in high current density region. The freezing period becomes longer and the cell resistance at shutdown increases after the cold start cycle. The results suggested that produced ice degrades the contact of CL and micro porous layer.
  • 鈴木 研悟, 大田 純, 田部 豊, 近久 武美 動力・エネルギー技術の最前線講演論文集 : シンポジウム 2014 (19) 101 -104 2014年06月25日 
    The deployment of energy saving and fuel substitution is affected by the mechanism of boiling and heating systems selection by household. This study developed the Conjoint Analysis to deal with the simultaneous selection of boiling and heating apparatuses, and analyzed the mechanism of boiling and heating systems selection by household living in rented houses in Sapporo by using conditional logit model. The result shows that the households in Hokkaido place more importance on initial cost than fuel cost when choosing boiling and cooling apparatuses. As the households using gas boiler and oil heater, about 50% of them selects gas boiler when they buy their houses, but the selection of heaters is not affected by present fuel types. About the half of households select the high efficient apparatuses, such as electric heat pumps and heat recovery-type boilers, without subsidies.
  • 赤澤 眞之, 鈴木 研悟, 田部 豊 エネルギー・資源学会研究発表会講演論文集 33 197 -202 2014年06月10日
  • Structural optimization of porous flow fields to improve water management ability of PEFC
    K. Suzuki, D. Sato, Y. Tabe, T. Chikahisa Proceedings of the 15th International Heat Transfer Conference IHTC15-9116 1 -15 2014年 [査読有り][通常論文]
  • ANALYSIS OF LIQUID WATER BEHAVIOR IN GAS DIFFUSION LAYERS OF PEFC USING LATTICE BOLTZMANN METHOD
    Y. Tabe, T. Azuma, Y. Honjo, K. Suzuki, T. Chikahisa Proceedings of the 25th International Symposium on Transport Phenomena PAPER 62 1 -6 2014年 [査読有り][通常論文]
  • 本庄 佑次, 鈴木 研悟, 田部 豊, 近久 武美 熱工学コンファレンス講演論文集 2013 291 -292 2013年10月18日 
    Flooding is one of the problems to be solved for practical use of PEFC. In this study, the numerical simulation using the lattice Boltzmann method (LBM) was developed to elucidate the liquid water behavior in a gas diffusion layer. In the equal density LBM code developed by the authors, there is a problem that setting value of water flow rate was not ensured. This paper explains the applied improvements for setting the inlet boundary conditions, keeping the fast calculation for the large-scale simulation, and the improved results. The instability of simulation, however, still remains as an unsolved issue, and the cause is also discussed.
  • 門脇 翼, 鈴木 研悟, 田部 豊, 近久 武美 熱工学コンファレンス講演論文集 2013 277 -278 2013年10月18日 
    The vanadium redox flow battery (VRB) has emerged as a viable grid-scale energy storage technology that offers energy storage solutions for renewable energy applications. In this study, we focus on the effect of material transport and electrolyte concentration distribution on cell performance. The original cell was specially designed for measurement of current density distribution, and the analysis method was established. In the method, the measured values just after the start of discharge were used to identify the non-uniform contact resistances, and the current density distribution unaffected by the measurement devices can be estimated. The measurement results showed that the current density decreases along the electrolyte flow, and the range of the current density and the cell performance are improved by increasing the electrolyte flow rate.
  • 天神林 大士, 鈴木 研悟, 田部 豊, 近久 武美 北海道支部講演会講演概要集 2013 (52) 139 -140 2013年09月28日
  • 石間 裕太, 鈴木 研悟, 田部 豊, 近久 武美 北海道支部講演会講演概要集 2013 (52) 107 -108 2013年09月28日
  • 高城 広輔, 鈴木 研悟, 田部 豊, 近久 武美 北海道支部講演会講演概要集 2013 (52) 103 -104 2013年09月28日
  • 赤澤 眞之, 鈴木 研悟, 田部 豊, 近久 武美 北海道支部講演会講演概要集 2013 (52) 137 -138 2013年09月28日
  • 赤堀 渉, 鈴木 研悟, 田部 豊, 近久 武美 北海道支部講演会講演概要集 2013 (52) 101 -102 2013年09月28日
  • 田熊 優一, 鈴木 研悟, 田部 豊, 近久 武美 北海道支部講演会講演概要集 2013 (52) 123 -124 2013年09月28日
  • 松川 大介, 鈴木 研悟, 田部 豊, 近久 武美 北海道支部講演会講演概要集 2013 (52) 121 -122 2013年09月28日
  • 佐藤 大樹, 鈴木 研悟, 田部 豊, 近久 武美 年次大会 : Mechanical Engineering Congress, Japan 2013 "J061043 -1"-"J061043-4" 2013年09月08日 
    According to earlier studies, the porous flow channel of Polymer Electrode Fuel Cell (PEFC) are more tolerant against flooding phenomenon, but less tolerant against dry-out phenomenon in comparison with conventional flow channels such as straight and serpentine type channels. However, the relationship between the porous structure and water management ability of porous media has not been clarified. This study investigated the influence of porosity and pore structure of porous bipolar plates on the tolerance of single cell against flooding and dry-out phenomena. The porous media produced by sintering Titanium fibers are used as the flow channels. The results show that the porous flow channel with lower porosity is more tolerant against dry-out phenomenon and less tolerant against flooding phenomenon. The best porosity of the flow channel seems to be in the range between 85-93%. The results also indicate that the porous media made of metal fibers with larger diameter has less water management ability because the special variety of porous and metal becomes larger.
  • 杉本 亮, 鈴木 研悟, 田部 豊, 近久 武美 年次大会 : Mechanical Engineering Congress, Japan 2013 "J061051 -1"-"J061051-3" 2013年09月08日 
    The use of the redox flow battery as a large-capacity rechargeable battery is one of the solutions for equalization of the outputs of wind power and photovoltaic power. In this study, we focus on electrode structure and the electrolyte flow of the redox flow battery, because those optimum design is necessary for improving total system performance. We tested with three kinds of electrode structure, and confirmed the influence of the electrolyte flow rate. At low SOC (state of charge), the discharge performance is greatly affected by the concentration overpotential at low flow rate of the electrolyte. In the case of the electrode structure with electrolyte flow channel, the effect of the concentration overpotential becomes larger in comparison with the electrode structure without electrolyte flow channel, indicating that most electrolyte flows in the flow channel and diffusion of the reactant is dominant for the cell performance. With the electrode without the channel (3mm or 6mm thick carbon felt), the effect of electrode thickness is small up to current density around 40mA/cm^2 even at low electrolyte flow rate, while thicker electrode improves the cell performance at high current density because of the larger effective reaction area of the carbon felt.
  • 山田 一樹, 鈴木 研悟, 田部 豊, 近久 武美 動力・エネルギー技術の最前線講演論文集 : シンポジウム 2013 (18) 7 -8 2013年06月19日 
    In polymer electrolyte fuel cells (PEFCs), the freezing of produced water makes cell performance worse below zero In this study, we investigated the freezing phenomena in the cathode catalyst layer (CL) by the experiments, and identified the effects of current density, cathode gas pressure, and oxygen concentration It was shown from the results that the ice distribution in the CL and the estimated amount of ice produced in the CL till the shutdown depend on the current density while they are independent of the cathode gas pressure and the oxygen molar concentration To clarify the main cause dominating these tendencies in the cold start, we introduced the effect of ice formation on an increase in the through-plane electrical resistance of the CL into the three phase boundary and the CL models, and examined the freezing mechanism in the CL
  • 鈴木 研悟, 中西 嵩裕, 田部 豊, 近久 武美 動力・エネルギー技術の最前線講演論文集 : シンポジウム 2013 (18) 227 -230 2013年06月19日 
    To spread the wind power technology, the power fluctuation risk of wind power plants, i.e.a risk of frequent and large reduction in the output caused by time-varying wind speeds, need to be decreased. Among measures against the risk, the geographical distribution of wind power plants needs to be examined first because additional facilities, such as backup thermal power plants or electricity storages, are not required. This study analyzes the risk reduction effect of geographically distributing wind power plants among the regions within Hokkaido. The mean-CVaR (Conditional Value at Risk) model is adopted to estimate optimum geographical distribution of the plants. We found that the geographical distribution can largely decrease the power fluctuation risk. Such a result indicates that the Hokkaido has enough variety of climates to largely decrease the power fluctuation risk of wind power plants by domestic geographical distribution.
  • 青木 利憲, 鈴木 研悟, 田部 豊, 近久 武美 動力・エネルギー技術の最前線講演論文集 : シンポジウム 2013 (18) 223 -226 2013年06月19日 
    When introducing renewable energies, the job-creation effect needs to be considered in addition to stable supply of energy and countermeasures against global warming. In this paper, we estimated the job-creation effect in the life cycle of wind power plants which is expected to be massively introduced into the Hokkaido, the life cycle of wind power generation includes manufacture of a wind turbine, power generation, operation and maintenance. Input-output table analysis is applied for the estimation, and wind power generation sector is newly added to the published version of the Hokkaido input-output table. The life cycle job-creation is estimated to be 1.34 person*year/GWh Of these, 0.57 person*year/GWh are Construction of wind turbine and 0.77 person*year/GWh are wind power generation About 30% of the life cycle job-creation is created outside the Hokkaido.
  • Jia-ming Gong, Nobuyuki Oshima, Yutaka Tabe PROCEEDINGS OF THE 11TH INTERNATIONAL CONFERENCE ON NANOCHANNELS, MICROCHANNELS, AND MINICHANNELS, 2013 2013年 [査読無し][通常論文]
     
    The effect of blend proportional factor a used in the free energy based two-phase flow LBM model with large density ratio on the shape description of a water droplet is investigated. The blend proportional factor a which combines the two kinds of staggered grids is adopted in the calculation process of the Poisson equation based fractional step method to satisfy the mass conservation in the LBM scheme, it is found to lead to varied degrees of shape deformation of a simulated liquid water droplet. The shape deformation degree of a liquid water droplet with certain dimensionless radius is measured by the radius lengths in 8 directions. The appropriate a which gives the better shape description accuracy of a water droplet with certain dimensionless radius is explored and its value change tendency with the dimensionless radius lengths is summarized The a's effect on the shape deformation is also presented
  • Yusuke Aoyama, Kengo Suzuki, Yutaka Tabe, Takemi Chikahisa PROCEEDINGS OF THE 11TH INTERNATIONAL CONFERENCE ON NANOCHANNELS, MICROCHANNELS, AND MINICHANNELS, 2013 2013年 [査読無し][通常論文]
     
    This paper examines the role of micro porous layers (MPLs) in Polymer Electrode Fuel Cells (PEFCs) by observing the cross-sectional distribution of condensed water inside a cathode side MPL In addition, the forms of water condensation in the vicinity of a MPL are also compared between two places, under flow channels and under lands, by observing both inside the MPL and an interface between the MPL and a catalyst layer (CL). The freezing method and a cryo-scanning electronic microscope (cryo-SEM) are used for the observation. The result under the non-flooded condition shows that condensed water does not accumulate inside the MPL. This result indicates that the water produced by PEFC power generation passes through the MPL as vapor state under non-flooded conditions.
  • Yutaka Tabe, Ryuji Kamijo, Yuji Honjo, Kengo Suzuki, Takemi Chikahisa PROCEEDINGS OF THE 11TH INTERNATIONAL CONFERENCE ON NANOCHANNELS, MICROCHANNELS, AND MINICHANNELS, 2013 2013年 [査読無し][通常論文]
     
    Numerical simulations using the lattice Boltzmann method (LBM) has been developed to elucidate the dynamic behavior of condensed water in a gas diffusion layer (GDL) of a polymer electrolyte membrane fuel cell (PEFC). Here, a LBM model of two-phase flow with equal densities was applied, because the condensed water behavior is less affected by the gas flow. The simulation results showed that the LBM applied here can simulate dynamic capillary fingering at low migration speeds of liquid water in a GDL, which is similar to the results of the LBM simulation with large density differences. Using the equal density LBM, we conducted efficient large-scale analyses to elucidate the effect of the GDL structure and wettability on the liquid water behavior inside of the GDL.
  • Masaru Kubo, Yutaka Tabe, Takemi Chikahisa Proceedings of the 8th International Conference on Modeling and Diagnostics for Advanced Engine Systems, COMODIA 2012 212 -217 2012年12月01日 [査読無し][通常論文]
     
    Diesel engines have high thermal efficiency, but suffer from the problem of relatively high emissions of NOx and particulate matter. The authors have shown that NOx is mostly generated at the flame tip region where mixing strength decrease significantly and maintains high temperatures for longer times than other regions. Based on this assumption, the authors proposed a combustion concept to reduce NOx by introducing high turbulence in the combustion chamber during the combustion period. The present paper reports simulations of the turbulence intensity and NOx reduction for an engine, which is designed to generate a strong jet from a special cell. The cell, which is termed CCD in the paper, is added to a direct injection diesel engine, and a small amount of fuel is injected into the cell to create the strong jet entering the main chamber. The numerical simulations showed that NOx increased significantly by the jet from the cell, the opposite of the expected result. However it was shown that a significant NOx reduction was obtained when the jet was injected in the same direction as the fuel injection, showing the viability of the concept. Copyright © 2012 by the Japan Society of Mechanical Engineers.
  • 大田 純, 鈴木 研悟, 田部 豊, 近久 武美 北海道支部講演会講演概要集 2012 (51) 137 -138 2012年10月20日
  • 佐藤 大樹, 鈴木 研悟, 田部 豊, 近久 武美 北海道支部講演会講演概要集 2012 (51) 129 -130 2012年10月20日
  • 杉本 亮, 鈴木 研悟, 田部 豊, 近久 武美 北海道支部講演会講演概要集 2012 (51) 127 -128 2012年10月20日
  • 山田 一樹, 鈴木 研悟, 田部 豊, 近久 武美 北海道支部講演会講演概要集 2012 (51) 131 -132 2012年10月20日
  • 青木 利憲, 鈴木 研悟, 田部 豊, 近久 武美 北海道支部講演会講演概要集 2012 (51) 135 -136 2012年10月20日
  • 門脇 翼, 鈴木 研悟, 田部 豊, 近久 武美 北海道支部講演会講演概要集 2012 (51) 125 -126 2012年10月20日
  • 本庄 佑次, 鈴木 研悟, 田部 豊, 近久 武美 北海道支部講演会講演概要集 2012 (51) 133 -134 2012年10月20日
  • 三嶋 峻平, 鈴木 研悟, 田部 豊, 近久 武美 北海道支部講演会講演概要集 2012 (51) 45 -46 2012年10月20日
  • Gong Jiaming, Oshima Nobuyuki, Tabe Yutaka, Yasser Ben Salah 年次大会 : Mechanical Engineering Congress, Japan 2012 "J056024 -1"-"J056024-5" 2012年09月09日 
    The emergence and transportation process of liquid water from a micro-pore on the gas diffusion layer surface under the action of gas flow in a polymer electrolyte membrane fuel cell (PEFC) is simulated by a modified free energy based lattice Boltzmann method (LBM) with large density ratio. A so called space averaged index function method is used to improve the mass conservation in the LBM scheme. And the effect of the GDL surface wettability on the liquid water removal efficiency is investigated. The simulation results show that the mass conservation of the LBM for the 3D simulation has been greatly improved and satisfied. The highly hydrophobic surface of GDL has a better performance in liquid water removal and less surface coverage area. It is shown that this LBM method can be an effective tool in simulating the two phase flow in the PEFC.
  • 上條 隆治, 田部 豊, 近久 武美 年次大会 : Mechanical Engineering Congress, Japan 2012 "J056026 -1"-"J056026-3" 2012年09月09日 
    For practical use of a polymer electrolyte fuel cell (PEFC), a flooding phenomenon is one of the problems to be solved. The flooding is caused by liquid water accumulated in the gas diffusion layer (GDL) and the gas flow channels and deteriorates the performance of the PEFC. Therefore, it is necessary to clarify the gas and liquid flow in the PEFC and to control the liquid water behavior appropriately. Our research group applied the lattice Boltzmann method (LBM) for the two phase flow with high density ratio, considering the effect of wettability, and has carried out the analyses of gas and liquid water to propose optimal structures of the PEFC. Here, the LBM is a method to reproduce the macroscopic flow by considering fluid as an aggregate of a virtual particle and calculating those collisions and translation sequentially, and suitable for the two-phase flow simulation with complex boundary geometries. In this study, we simulated liquid water behavior inside of the GDL applying a low density ratio LBM with shorter computational time instead of the high density ratio model. It was confirmed that the effect of large density difference on the liquid water behavior is negligible because of the weak gas flow inside of the GDL. Using the LBM with low density ratio, we tried efficient large-scale analyses in the GDL to elucidate the effect of the GDL structure and wettability on the liquid water behavior inside of the GDL.
  • 小林 将矢, 田部 豊, 近久 武美 年次大会 : Mechanical Engineering Congress, Japan 2012 "J056025 -1"-"J056025-3" 2012年09月09日 
    Because electron, proton, and oxygen are necessary for the cathode reaction in polymer electrolyte fuel cell, achieving the optimum structure of electrode catalyst layer and the efficient transport of the reactants is significantly effective to reduce the usage of Pt catalyst in polymer electrolyte membrane fuel cells (PEFCs). In this paper, we estimated the major parameters such as the radius of the carbon agglomerate with polymer electrolyte and the thickness of the catalyst layer from structural observation of the fabricated CCM by a Scanning Electron Microscope (SEM). The polarization characteristics of the cell performance were calculated using an agglomerate model with the experimentally estimated parameters, and the simulation model was validated by comparing the simulated and experimental results. Then, we evaluated the effects of the major parameters such as the polymer electrolyte film thickness covering carbon agglomerates on the cell performance by the simulation, and present a new concept effective for reducing the identified major resistances such as the oxygen diffusion resistance in the polymer by controlling the film structure of polymer electrolyte.
  • 柏瀬 浩司, 田部 豊, 近久 武美 動力・エネルギー技術の最前線講演論文集 : シンポジウム 2012 (17) 107 -108 2012年06月20日 
    This paper shows an analysis of water transport phenomena in MEA in PEM electrolysis cell. In previous study, it was shown that the change of water transport pattern in diffusion layer and catalyst layer doesn't affect performance and Nafion membrane may be directly related to performance. In this study, a numerical analysis to clarify the water transport phenomena in MEA based on the experimental data (the amount of discharged water from the cathode and the impedance) was developed. The result showed that the effect of osmotic force on the water transport through the MEA is far larger than that of diffusion force and water content in Nafion membrane may increase as current density increases.
  • 糸見 宗志, 佐藤 大和, 田部 豊, 近久 武美 動力・エネルギー技術の最前線講演論文集 : シンポジウム 2012 (17) 339 -340 2012年06月20日 
    As a smaller and lighter hydrogen PEFC, we adopted "Dead-end mode" and "Air-breathing" systems and tried to improve the cell performance with a small fan. In this paper, the effects of cathode air flow rate and cell temperature on the cell performance were investigated experimentally. It was shown that under low relative humidity conditions higher flow rate makes the CCM drier and causes dryout, but suppresses the increase in the cell temperature by the reaction heat. The increase in the cell temperature also induces dryout, so appropriate temperature management as well as water management by the small fan is important for stable high cell performance of this PEFC system.
  • 本庄 佑次, 那須 拓哉, 近久 武美, 田部 豊 動力・エネルギー技術の最前線講演論文集 : シンポジウム 2012 (17) 345 -346 2012年06月20日 
    For improvement on performance of a polymer electrolyte fuel cell (PEFC), it is necessary to ensure appropriate management of reaction gas, generated water and temperature in the cell. In this study, we investigated possibilities of a structure without GDL and an internal cooling method in a PEFC with porous cathode separator experimentally. The results showed that the performance of a single cell without GDL decreases due to uneven contact and high contact resistance between the porous separator and the catalyst layer. It is considered that applying a micro porous layer to the interface of the porous cathode separator is effective for the improvement. It was also shown that the internal cooling method using evaporative latent heat has effects of not only cooling cell but also maintaining high humidity inside the cell even if humidity of supply gas is low.
  • 青山 祐介, 鈴木 研悟, 田部 豊 エネルギー・資源学会研究発表会講演論文集 31 323 -326 2012年06月05日
  • Jia-ming Gong, Nobuyuki Oshima, Eru Kurihara, Yutaka Tabe PROCEEDINGS IF THE ASME 9TH INTERNATIONAL CONFERENCE ON NANOCHANNELS, MICROCHANNELS AND MINICHANNELS 2011, VOL 1 1 239 -248 2012年 [査読無し][通常論文]
     
    The appropriate blend proportional factor value which combines two kinds of staggered grids used in Lattice Boltzmann Method (LBM) for simulating the multiphase flow phenomena with large density ratio in the Polymer electrolyte fuel cell (PEFC) is fixed on. The shape deformation of the water droplet is found when using the two kinds of staggered grids to prevent the pressure oscillation when solving the Poisson equation of this LBM model and the shape of the water droplet varies with the changes of the blend proportional factor values. Two methods are adopted to find out the two staggered grids' appropriate blend proportional factor value that can diminish or minimize the deformation of the droplet. The first one is to compare the simulation results of different blend proportional factors with the theoretical value and find the one mostly approaches the theoretical value; the second one is to compare the current velocity divergences of the two staggered grids using the results calculated by different blend proportional factor values. A water droplet resting in a tunnel is simulated with different blend proportional factor values and the appropriate value is decided.
  • Takemi Chikahisa, Yutaka Tabe, Kazumasa Kadowaki PROCEEDINGS OF THE ASME 10TH INTERNATIONAL CONFERENCE ON NANOCHANNELS, MICROCHANNELS AND MINICHANNELS 2012 141 -147 2012年 [査読無し][通常論文]
     
    Micro-porous layers (MPLs) play an important role in the water management of polymer electrolyte fuel cells (PEFCs), but details of the mechanism that works to suppress water flooding has not been fully understood. In this study, the authors investigated water distribution at the interface between the MPL and the catalyst layer (CL) at the cathode side to clarify the effect of the MPL on the discharge of produced water. A freezing method was applied to observe the distribution of the condensed water, and the ice distribution on the CL surface was quantified by image processing. The effects of operating conditions on the water distribution were examined at normal temperature conditions. The distribution of ice formed on the surface of the CL with and without MPL after -10 degrees C cold start operation was also established. Water transport rate in the vapor phase was analyzed based on temperature and vapor pressure gradient considerations. The experiments and the analysis showed that the MPL functions to prevent accumulation of water on the surface of the CL, resulting in less water flooding.
  • 田部 豊, 那須 拓哉, 森岡 怜史, 近久 武美 日本機械学会論文集C編 78 (789) 1151 -1159 2012年 [査読無し][通常論文]
     
    A polymer electrolyte membrane fuel cell (PEFC) with a porous-flow-field separator has been proposed as an alternative to cells with gas flow channels. In this study, basic characteristics of a PEFC with porous flow field were identified using a cell allowing local current density measurement and direct observation of the condensed water at the surface of porous material. It was shown that a stable operation can be maintained under conditions at high current density and low stoichiometric ratio of cathode air, but an operation with low relative humidity of reaction gases is difficult with the porous type separator. To clarify the detailed causes of these characteristics, the internal phenomena were investigated using a cell specially made for the cross-sectional observation of the separator or the temperature distribution measurement. The direct observations of the condensed water at the cross-section of porous flow field showed that the porous type cell is superior in drainage performance of the condensed water from the surface of gas diffusion layer (GDL), and the hydrophilic property of the porous material is important for better cell performance under high current density conditions. The measurements of temperature distribution on the anode GDL surface indicated that the increase in temperature near the reaction area tends to be larger in the porous type cell than in channel type due to the lower thermal conductivity of the porous media, and this resulted in the unstable operation with low relative humidity conditions.
  • 木村 恵敬, 田部 豊, 近久 武美, 二口 尚樹 熱工学コンファレンス講演論文集 2011 291 -292 2011年10月28日 
    2D computer simulation assists in the decision of growth parameters to reduce the crystal defects of GaAs crystal in liquid encapsulated Czochralski (LEC) method. In this paper, we numerically investigated the reason why the 450mm-long crystal has more crystal defects than the 350mm-long crystal by comparing heat exchange, temperature distribution and velocity vector in the source melt at several stage of the growth. The simulation results indicated that large heat release from crystal and small heat release from crucible bottom are advantageous to the crystal growth with few defects. It is also necessary that forced convection and natural convection of GaAs melt is delicately controlled by the crucible rotation rate and the temperature distribution.
  • 中西 嵩裕, 田部 豊, 近久 武美 北海道支部講演会講演概要集 2011 (50) 211 -212 2011年10月01日
  • 青山 祐介, 田部 豊, 近久 武美 北海道支部講演会講演概要集 2011 (50) 207 -208 2011年10月01日
  • 小林 将矢, 田部 豊, 近久 武美 北海道支部講演会講演概要集 2011 (50) 205 -206 2011年10月01日
  • 久保 多, 田部 豊, 近久 武美 北海道支部講演会講演概要集 2011 (50) 201 -202 2011年10月01日
  • 田部 豊, 黒川 真伍, 近久 武美 動力・エネルギー技術の最前線講演論文集 : シンポジウム 2011 (16) 189 -190 2011年06月22日 
    Long-term change of energy system structure in Japan was analyzed to investigate the effect of CO_2 emission reduction level using MARKAL model. The MARKAL is composed of energy resources, energy supply technologies, energy ultimate demand technologies and energy service demands with them connected by energy carriers. This paper presents analyses investigating the CO_2 reduction cost and the energy structure change until 2050. Here, we focused on the domestic investment to reduce CO_2 emission. It was shown that the CO_2 reduction until 40% level promotes the energy conversion from coal to natural gas and it causes the increase in total cost of the imported fuel. The higher CO_2 reduction, however, increases the domestic investment for low-emission vehicles, photovoltaic power generation and so on, and decreases the outward investment, although the total CO_2 reduction cost is increased. This contributes to the revitalization of Japanese economy, together with the reduction of outward investment.
  • 佐藤 大和, 田部 豊, 近久 武美 動力・エネルギー技術の最前線講演論文集 : シンポジウム 2011 (16) 183 -184 2011年06月22日 
    The methods for smaller and lighter PEFC systems include "Dead-end mode" and "Air-breathing". However, it is difficult to discharge water, and PEFC systems using these methods have agenda that they make it easier to flood. In this paper, we investigated the effect of condensed water on the cell performance experimentally. Shorter operation time and more condensed water were observed at higher relative humidity (RH) and higher current density (0.3A/cm^2) condition than at lower RH and lower current density (0.2A/cm^2). At lower RH and lower current density, it was confirmed that the causes of shutdown are flooding by the condensed water on the channel bottoms at the cathode side and the water on the GDL surface at the anode side. We were able to prevent the cathode flooding by continuous removal of the accumulated water and the anode flooding by less-frequent hydrogen purge.
  • 市川 亮輔, 田部 豊, 近久 武美 動力・エネルギー技術の最前線講演論文集 : シンポジウム 2011 (16) 185 -186 2011年06月22日 
    In PEM fuel cell below zero, freezing under the cold start sometimes causes a deterioration of cell performance in normal operation. In particular, this phenomenon is especially prominent after the -10℃ start than after the -20℃ that. This is because the ice formed at the interface between the cathode catalyst layer and GDL at the -10℃ start. This paper focused on the effect of current density and tightening pressure of the cell, and investigated the mechanism of the -10℃ start effect on normal operation. The results showed that the performance deterioration is large as current density at the -10℃ start is small. This phenomenon became prominent in case of small tightening pressure of the cell because of wide ice formation on the catalyst layer surface.
  • 門脇 主将, 田部 豊, 近久 武美 動力・エネルギー技術の最前線講演論文集 : シンポジウム 2011 (16) 439 -442 2011年06月22日 
    Micro Porous Layer (MPL) play an important role in the water management of PEFC, but details of the mechanism to suppress water flooding has not been fully understood. In this study, we investigated condensed water distribution at the interface between MPL and MEA to clarify the effect of MPL on discharge of produced water. Freezing method was applied to observe the distribution of the condensed water, and the distribution on the MEA surface was quantified by a binary image processing. The results indicated less amount of condensed water distribution on the MEA surface in the case of GDL with MPL than in the case of GDL without MPL. Next, comparing normal operation with start-up temperature -10℃, there is large amount of condensed water on the MEA surface after operation at -10℃. Based on these results, the MPL has a role to prevent accumulated water on the surface of MEA, and suppresses water flooding. In operation at -10℃, generated water which becomes supercooled water freezes at the interface between MEA and MPL, and large ice agglomerates are generated on the surface of MEA.
  • Yutaka Tabe, Masataka Saito, Kaoru Fukui, Takemi Chikahisa Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B 77 (773) 160 -167 2011年 [査読無し][通常論文]
     
    Cold start characteristics of a polymer electrolyte fuel cell were investigated experimentally, and microscopic observations were conducted to clarify the freezing mechanism in the cell. The results shows that the freezing mechanisms are classified into two types: freezing in catalyst layer at very low temperature like 20 C, and freezing of supercooled water at the interface between cathode catalyst layer and micro porous layer at near 0 C like 10 C. The amount of produced water in each the processes is related to the initial wet condition of the membrane because there is a period of back diffusion of produced water into the membrane. It is also shown that the performance of a subsequent normal temperature operation at 30 C after the shutdown in the cold start is temporarily deteriorated after the freezing at 10 C, but not after the freezing at 20 C. The ice formed at the interface between the catalyst and the micro porous layers is estimated to cause the temporal deterioration, and the function of micro porous layer on the gas diffusion layer is also discussed. © 2011 The Japan Society of Mechanical Engineers.
  • Satoshi Sakaida, Yutaka Tabe, Takemi Chikahisa SAE Technical Papers 2011年 [査読無し][通常論文]
     
    To design diesel engines adapted to future exhaust gas regulation, it would be advantageous to have a driving mode simulation for vehicle performance and exhaust emissions, including after-treatment systems. The combustion model for this objective must be able to simulate the engine performance in very short time. We have tried to develop such diesel engine combustion model by adding the improvements to the Hiroyasu model. In this paper, we detail the improvements that were added to this model and comparisons the calculated results by the improved model with experimental result. © Copyright 2011 Society of Automotive Engineers of Japan, Inc. and SAE International.
  • 田部 豊, 西野 昌芳, 高松 宏行, 近久 武美 日本機械学会論文集C編 77 (774) 301 -312 2011年 [査読無し][通常論文]
     
    Because electron, proton, and oxygen are necessary for the cathode reaction in polymer electrolyte membrane fuel cells, achieving the optimum structure of electrode catalyst layer and the efficient transport of the reactants is significantly effective to reduce the usage of Pt catalyst. In this study, we developed a three-phase boundary and a cathode catalyst layer models to clarify structures appropriate for the efficient transport, and the dominant effects of the catalyst layer structures and the properties were investigated using the models. Additionally, the evaluation equations were presented to understand the effect of structure simply, and the effectiveness was confirmed by the comparison of the results calculated by the equation and the model simulation. From the results, suitable structures of the porosity, catalyst layer and polymer electrolyte thicknesses, for the gas diffusion and proton conduction were clarified, and it was presented that the solubility of oxygen in the polymer is one of the dominant factors and increasing in the solubility is extremely effective for reduction of the Pt usage.
  • Yutaka Tabe, Masayoshi Nishino, Hiroyuki Takamatsu, Takemi Chikahisa JOURNAL OF THE ELECTROCHEMICAL SOCIETY 158 (11) S27 -S27 2011年 [査読無し][通常論文]
  • 佐藤 大和, 田部 豊, 近久 武美 北海道支部講演会講演概要集 2010 (49) 103 -104 2010年11月07日
  • 門脇 主将, 田部 豊, 近久 武美 北海道支部講演会講演概要集 2010 (49) 21 -22 2010年11月07日
  • 朱 前進, 田部 豊, 近久 武美 北海道支部講演会講演概要集 2010 (49) 107 -108 2010年11月07日
  • 木村 恵敬, 田部 豊, 近久 武美 北海道支部講演会講演概要集 2010 (49) 23 -24 2010年11月07日
  • 境田 悟志, 田部 豊, 近久 武美 北海道支部講演会講演概要集 2010 (49) 109 -110 2010年11月07日
  • 那須 拓哉, 森岡 怜史, 田部 豊, 近久 武美 北海道支部講演会講演概要集 2010 (49) 63 -64 2010年11月07日
  • 難波 陵二, 田部 豊, 近久 武美 北海道支部講演会講演概要集 2010 (49) 25 -26 2010年11月07日
  • 市川 亮輔, 田部 豊, 近久 武美 北海道支部講演会講演概要集 2010 (49) 105 -106 2010年11月07日
  • 下館 拓也, 田部 豊, 近久 武美 計算力学講演会講演論文集 2010 (23) 305 -306 2010年09月23日
  • 近久 武美, 大曽根 靖夫, 黒田 明慈, 桑原 不二朗, 坂下 弘人, 戸谷 剛, 中村 祐二, 山田 雅彦, 田部 豊 伝熱 : journal of the Heat Transfer Society of Japan 49 (208) 19 -28 2010年07月01日 [査読無し][通常論文]
  • 難波 陵二, 齋藤 正尭, 田部 豊, 近久 武美 動力・エネルギー技術の最前線講演論文集 : シンポジウム 2010 (15) 387 -388 2010年06月20日 
    In PEM Fuel Cell below zero, freezing under cold start sometimes causes a temporal deterioration of cell performance in normal temperature operation. This paper investigates the mechanisms of the cold start effect on operation at normal temperature and the ice fomation in catalyst layer. The observation was performed after the cell at the freezing temperature. The results showed that the performance deterioration is caused by the ice formed at the interface between the catalyst layer and GDL, and the control of the ice amount is important to prevent depression. Cryo-SEM observation showed that there is ice in the catalyst layer, which causes the shut down, and the distribution of formed ice is affected by the operation condition.
  • 那須 拓哉, 森岡 怜史, 田部 豊, 近久 武美 動力・エネルギー技術の最前線講演論文集 : シンポジウム 2010 (15) 385 -386 2010年06月20日 
    This study conducted perfomance evaluation of single cell with porous cathode separataor. The direct observation of the porous separator cross-section and the impedance spectra were applied. The observation showed that the porous separator is superior in the drainage performance from the GDL surface, and the hydrophily of separator fiber is important for the performance. The results of impedance spectra indicated that the porous separator is superior to the serpentine separator in the supply of reactant gas.
  • Kyaw Swar Soe Naing, Yutaka Tabe, Takemi Chikahisa PROCEEDINGS OF THE ASME INTERNATIONAL HEAT TRANSFER CONFERENCE - 2010, VOL 5 5 61 -69 2010年 [査読無し][通常論文]
     
    To maintain proton exchange membrane fuel cells (PEFC) at high efficiencies without flooding, it is necessary to control the liquid water transport in the gas diffusion layer (GDL). This experimental study investigates the effects of the GDL fiber direction on the cell performance using an anisotropic GDL. The results of the experiments showed that the efficiency of the cell was much better when the fiber direction was perpendicular to the channel direction, and that the cell with perpendicular fibers was more tolerant to flooding than the cell with fibers parallel to the channel. To determine the mechanism that gives rise to the fiber direction effects, the liquid water behavior in the channel was observed through a glass window on the cathode side. Additionally, a small cell with a 2 cm(2) active area was made, to investigate the water distribution inside the GDL by freezing the water and observing the ice distribution. These ice pictures showed that reactions are more active under channels than under ribs. This is because the accumulated water prevents reaction under the ribs, and indicates the importance of water removal from the rib zones.
  • 西野 昌芳, 田部 豊, 近久 武美 北海道支部講演会講演概要集 2009 (48) 161 -162 2009年11月28日
  • 佐々木 隆行, 田部 豊, 近久 武美 北海道支部講演会講演概要集 2009 (48) 163 -164 2009年11月28日
  • 黒川 真伍, 田部 豊, 近久 武美 北海道支部講演会講演概要集 2009 (48) 157 -158 2009年11月28日
  • 下舘 拓也, 田部 豊, 近久 武美 北海道支部講演会講演概要集 2009 (48) 159 -160 2009年11月28日
  • 宮田 典亜, 菊田 和重, 田部 豊, 近久 武美 熱工学コンファレンス講演論文集 2009 135 -136 2009年11月06日 
    The phenomenon in the vaporizer for low volatile organic solvent is analyzed and the performances of the two types of vaporizer are evaluated. The numerical simulation shows that the vaporizer using a two-fluid nozzle cannot fully utilize the tube space because of the strong penetration characteristic and the low adjusting capability of the flow pattern. The vaporizer with ultrasonic nozzle and gas inlets is presented to avoid the disadvantages above. It is demonstrated that the ultrasonic nozzle type can achieve more than 6 times particle residence time as compared with the two-fluid nozzle type and it can be applied for the evaporator of the low volatile organic solvents.
  • 田部 豊, 鵜野 幸太, 近久 武美 動力・エネルギー技術の最前線講演論文集 : シンポジウム 2009 (14) 393 -394 2009年06月28日 
    Long-term CO_2 emission analyses on the energy structure in Japan were conducted using the MARKAL. The MARKAL model is one of analysis tools to evaluate the long-term change of energy system in a country, and is composed of energy resources, energy supply technologies, energy ultimate demand technologies and energy service demands with them connected by energy carriers. This paper presents the analyses investigating energy structure at house and effects of CO_2 capture and storage (CCS) until 2050. It was shown that the usage of electricity and gas is strongly affected by the investment costs, and the large reduction is needed for CGS widespread use. The results also showed that the CCS is effective in the case that the installed capacity of nuclear power plant, and the effective capture of CO_2 reduces the social costs for the reduction of CO_2 emission.
  • スーナイ ジョースワ, 菊田 和重, 田部 豊, 近久 武美 動力・エネルギー技術の最前線講演論文集 : シンポジウム 2009 (14) 163 -164 2009年06月28日
  • 田部 豊 日本機械学会誌 112 (1085) 311 -311 2009年 [査読無し][通常論文]
  • 大島 伸行, 田部 豊, 栗原 央流 燃料電池 9 (2) 6 -12 2009年 [査読無し][通常論文]
  • Takemi Chikahisa, Kazuhiko Kudo, Katsunori Hanamura, Yutaka Tabe JOURNAL OF THERMAL SCIENCE AND TECHNOLOGY 4 (3) 324 -324 2009年 [査読無し][通常論文]
  • Kazushige Kikuta, Yutaka Tabe, Takemi Chikahisa, Yusuke Takashima Proceedings of the 7th International Conference on Modeling and Diagnostics for Advanced Engine Systems, COMODIA 2008 695 -702 2008年12月01日 [査読無し][通常論文]
     
    To design diesel engines adapted to future exhaust gas regulations, it would be advantageout to have a driving mode simulator for vehicle performance and exhaust emissions, including after-treatment systems. A driving mode simulator with simple and high-speed calculation characteristics was developed with a diesel combustion model based on the Hiroyasu model. In the air entrainment model this report adds the effect of the air entrainment due to turbulent flow in a cylinder, and in the ignition delay model we considered the partial pressure of oxygen for better fitting the EGR effect. To simulate premixed compression ignition engines, the Schreiber's reduced kinetic model for ignition and combustion was also included. Arrhenius parameters for the rate constants were modified to fit the ignition delay. As a result it was possible to simulate low-temperature oxidation and the main combustion. The paper details the modifications and demonstrates the usefulness of the modified model by comparisons with experimental results. Copyright © 2008 by the Japan Society of Mechanical Engineers.
  • 森岡 怜史, 田部 豊, 近久 武美 可視化情報学会誌. Suppl. = Journal of the Visualization Society of Japan 28 (2) 103 -104 2008年09月15日
  • 大島 伸行, 栗原 央流, 田部 豊 化学装置 50 (9) 17 -22 2008年09月 [査読無し][通常論文]
  • 小境 正也, 奥澤 務, 佐竹 弘之, 高橋 宏, 田部 豊, 近久 武美 動力・エネルギー技術の最前線講演論文集 : シンポジウム 2008 (13) 249 -250 2008年06月18日 
    High power density enhances polymer electrolyte fuel cell with widely varied applications. Our investigation focused on the refinement of the reactant gas flow field at the bipolar plate in order to increase the fuel cell performance. Applying a porous material to the reactant gas flow field is one possible method. Expected advantages of a porous flow field are an increase in reactant gas diffusivity and electron conductivity allover the electrode. An investigation was carried out to evaluate the feasibility of a porous flow field. The Lattice Boltzman simulation indicated that surface wettability and pore structure control have prospect of gas and water flow field separation. The experiment of porous flow field showed same level performance of channel type.
  • 山下 浩平, 菊田 和重, 田部 豊, 近久 武美 動力・エネルギー技術の最前線講演論文集 : シンポジウム 2008 (13) 245 -248 2008年06月18日 
    To maintain the high performance in PEFC, water management which keep an electrolyte film to the adequate wet is necessary. The gas diffusion layer (GDL) fulfils large role in it. In this study cell characteristics was tested using GDL with various characteristics. As a result it was showed that the rigidity was necessary for GDL to keep the contact resistance stably low. In GDL with the same carbon-fiber direction, the difference of the cell performance occurred by changing the channel direction. It was thought that the gas diffusion under the separator rib was changed, because the difference could not be seen in both of the visualization image.
  • 齋藤 正尭, 田部 豊, 菊田 和重, 近久 武美 動力・エネルギー技術の最前線講演論文集 : シンポジウム 2008 (13) 233 -236 2008年06月18日 
    To develop the numerical simulation of PEM fuel cell, verification experiments and data acquisition of physical parameters were conducted by mechanical and electrochemical measurements. The mechanical measurement showed that the GDL deformation due to clamping by separator lands is important phenomenon to estimate an actual flow in the cell, and the unique deformation behavior of GDL with fabric construction was clarified. From the electrochemical measurement, the methods to acquire the parameters used in the simulation, proton conductivity σ_m, electrochemically active Pt area a, exchange current density i_o and cathode transfer coefficient α_c were established. Furthermore, the possibility to analyze flooding phenomenon by applying this electrochemical measurement was presented.
  • 瀬野 堅司, 田部 豊, 近久 武美 エネルギーシステム・経済・環境コンファレンス講演論文集 = Proceedings of the ... Conference on Energy, Economy, and Environment 24 293 -296 2008年01月30日
  • スーナイ ジョースワ, 田部 豊, 近久 武美 熱工学コンファレンス講演論文集 2007 399 -400 2007年11月23日 
    This paper analyzes the effectiveness of CGS for the CO_2 and cost reductions in the prospective distributed energy system, which is a future type system using heat pump for heating instead of boiler. The CGS effectiveness in different building types and regions are discussed, where COP dependencies on the ambient temperature and demands of heating or cooling are considered. The results show that CO_2 reduction effect of CGS in the prospective system is lower than that in the conventional system but the cost reduction effect is higher. It was also shown that the prospective CGS is more advantageous and appropriate in cold region.
  • 高嶋 祐介, 近久 武美, 田部 豊, 菊田 和重 北海道支部講演会講演概要集 2007 (46) 145 -146 2007年09月29日
  • 李 勇柱, 木保 康介, 田部 豊, 菊田 和重, 近久 武美 北海道支部講演会講演概要集 2007 (46) 15 -16 2007年09月29日
  • 高松 宏行, 田部 豊, 菊田 和重, 近久 武美 北海道支部講演会講演概要集 2007 (46) 13 -14 2007年09月29日
  • 吉田 大輪, 安田 陽介, 田部 豊, 菊田 和重, 近久 武美, 小境 正也 動力・エネルギー技術の最前線講演論文集 : シンポジウム 2007 (12) 259 -262 2007年06月13日 
    The objective of this paper is to observe water production behavior inside of the cell and to analyze its effect on current distributions over the reaction area. A fuel cell was made to allow direct observation of the phenomena in cathode side and local current density measurement in anode side. The experimental results showed that the cell performance and current density distribution of air operation is strongly affected by the condensed water compared with those of O_2 operation, although the drainage of air operation is superior. It was also shown from the comparison experiments of separator type that the serpentine separator has advantage to drain away the condensed water because of its high gas velocity, and may make gas paths deep in the gas diffusion layer. On the other hand, when the condensed water is drained efficiently, the straight separator can realize homogeneous current density distribution because of its shorter channel paths.
  • 嘉数 啓, 田部 豊, 近久 武美 エネルギーシステム・経済・環境コンファレンス講演論文集 = Proceedings of the ... Conference on Energy, Economy, and Environment 23 465 -468 2007年01月25日
  • スーナイ ジョースワ, 田部 豊, 近久 武美 熱工学コンファレンス講演論文集 2006 59 -60 2006年11月23日 
    This paper analyzes CGS effectiveness for the CO_2 reduction, and the effects of use of heat pump for heating were investigated at various power plant efficiencies and the COP of heat pump. In the next-generation, it is essential to apply the system with heat pump for heating instead of boiler. The calculation results show that CGS benefit for CO_2 emission is strongly affected by the COP of heat pump and the electric efficiency of CGS is needed to be close to that of power plant efficiency to have a beneficial effect in the prospective system with heat pump. The electrical efficiency of CGS must be higher than the present system with boiler to get the benefits.
  • 木保 康介, 田部 豊, 菊田 和重, 近久 武美 北海道支部講演会講演概要集 2006 (45) 171 -172 2006年09月25日
  • 嘉数 啓, 田部 豊, 近久 武美 北海道支部講演会講演概要集 2006 (45) 183 -184 2006年09月25日
  • T Chikahisa, Y Tabe, M Yamauchi PROCEEDINGS OF THE SECOND IASTED INTERNATIONAL CONFERENCE ON ADVANCED TECHNOLOGY IN THE ENVIRONMENTAL FIELD 173 -+ 2006年 [査読無し][通常論文]
     
    Increases in CO2 emissions from vehicles is a major concern in automotive societies, and a variety of car types offering lower CO2 emissions, hybrid cars, natural gas cars, electric cars, and cars with fuel-cell, are being investigated intensively. However the level of performance and cost that must be achieved for future cars to be acceptable in the market and the percentage of cars that must be replaced for the protection of the environment is not clear. This paper investigates future market growth of low-emission vehicles and analyzes CO2 emission changes for passenger cars in Japan, England, and the United States. A consumer model for selecting vehicles, which was established in the previous report, was calibrated with statistical data from each of the countries. The results of the analysis shows that England has the highest potential for reducing CO2 emissions among these countries, but that this is stili insufficient to accomplish the Kyoto protocol requirements. Market shares of low emission vehicles are similar in Japan and England, and hybrid cars appear to be able to reach a substantial shares in 10 years, while the share of fuel cell powered cars will be very small. The critical cost for fuel eel I powered cars to gain a 10% share in 2015 is shown for the three countries.
  • 荒戸景太, 近久武美, 田部豊, 菊田和重, 金子友海, 港明彦, 島崎直基 自動車技術会学術講演会前刷集 (124-06) 2006年
  • 朴 相均, 菊田 和重, 田部 豊, 近久 武美 熱工学コンファレンス講演論文集 2005 269 -270 2005年11月02日 
    This study investigates drying condition for the case when a small fan is added to a free-breathing proton electrolyte membrane fuel cell (PEMFC) operating with dry H_2 and air. Polarization tests were conducted on PEMFCs at cell temperatures between 30 and 50℃. The result shows that the cell performance strongly depends on the cell temperature and the stoichiometric flow-rates of cathode gas. The cell performance increases as cell temperature decreases from 50 to 30℃. In the condition where the air flow-rate is quite large, internal resistance increases due to the progress of drying, but it is compensated by the decreased concentration over-potential. The maximum performance was obtained at a small air flow-rate in a narrow pass between dry-out and flooding. This indicates that the flow rate of the fan should be designed relatively small, if a cell design of avoiding flooding is possible.
  • 大津 翔, 近久 武美, 田部 豊 北海道支部講演会講演概要集 2005 (44) 138 -139 2005年10月08日
  • 近久 武美, 田部 豊, 川口 肇 環境工学総合シンポジウム講演論文集 2005 (15) 311 -314 2005年07月06日 
    Forest in Siberia plays important role for absorbing carbon dioxide. However, resent increase in forest fires, due to both human negligence and global warming, appears to cause significant damage on the forest. The present research tries to establish simulation model, which enables to predict forest fire effect over thousand years, and to evaluate the effects of forest fire on long term balance of CO_2 in Siberia. The result of the analysis shows that the major factor affecting on long-term forest area is the probability of fire extension and the number of fires in a year would not make apparent difference in the forest area due to feedback mechanism of fire sizes. The prediction was confirmed by the analysis of the remote sensing data. The paper shows the substantial danger of global warming effect on long-term forest area, whereas human negligence effect may be small.
  • 岩佐 能孝, 田部 豊, 近久 武美 環境工学総合シンポジウム講演論文集 2005 (15) 454 -457 2005年07月06日 
    This paper presents mapping method to show characteristics of cogeneration systems (CGS) for the reduction of carbon dioxide emission and economy. In this method, effects of CGS can be consolidated into rated reduction ratio, relative reduction ratio map, demand repetition map and weight map. By lapping these maps, it can be easy to evaluate compatibility with each building types and optimal installed capacity. Analyzed charts are useful to evaluate quantitative effects of CGS for various areas and price rates of electric/gas from average annual demand of electricity and heat.
  • 川口 肇, 田部 豊, 近久 武美 エネルギーシステム・経済・環境コンファレンス講演論文集 = Proceedings of the ... Conference on Energy, Economy, and Environment 21 445 -448 2005年01月26日
  • 朴 相均, 菊田 和重, 田部 豊, 近久 武美, 菱沼 孝夫 日本機械学會論文集. B編 = Transactions of the Japan Society of Mechanical Engineers. B 71 (711) 2808 -2815 2005年 [査読無し][通常論文]
     
    The performance of free-breathing polymer electrolyte membrane fuel cell (PEMFC) was studied experimentally and the effect of cathode separator structure on the cell performance was investigated. Two types of cathode separators were used for the cell with 18cm^2 active area: the open type had parallel rectangular open-slits and the cannel type had straight vertical channels with their ends open. The polarization curve, the cell impedance and the contact pressure distribution of the separator were measured for each type. It was clarified that realizing uniform contact pressure of the cell layers is difficult for the open type separator, which causes higher contact resistance and lower cell performance. On the other hand, the channel type separator can keep low contact resistance, and the cell performance is strongly affected by the natural convection inside the channel. It was found that the channel type separator can achieve high performance by optimization of channel design and this type is suitable for the free-breathig PEMFC. A computational three dimensional analysis was performed for the free-breathing cannel type PEMFC with the different channel depths, and it identified the influece of natural convection.

受賞

  • 2021年03月 日本機械学会 熱工学部門 貢献表彰
     
    受賞者: 田部 豊
  • 2020年04月 日本機械学会 日本機械学会賞(論文)
     Scale model experiments for evaluation of liquid water transport in the gas diffusion layer of PEFCs 
    受賞者: Yutaka TABE;Satoshi SAKAIDA;Takemi CHIKAHISA
  • 2000年05月 日本伝熱学会 奨励賞
     
    受賞者: 田部 豊

共同研究・競争的資金等の研究課題

  • リチウム空気電池内電解液濡れ現象のCryo-SEM観察と高性能電極構造の解明
    文部科学省:科学研究費補助金(基盤研究(B))
    研究期間 : 2021年 -2023年 
    代表者 : 植村 豪, 田部 豊
  • PEM燃料電池の高出力化のためのマルチスケール水・酸素輸送促進
    文部科学省:科学研究費補助金(基盤研究(B))
    研究期間 : 2021年 -2023年 
    代表者 : 田部 豊, 植村 豪, 境田 悟志
  • PEM形燃料電池の氷点下起動におけるマルチスケール水輸送・凍結分布制御
    文部科学省:科学研究費補助金(基盤研究(B))
    研究期間 : 2017年 -2019年 
    代表者 : 田部 豊, 近久 武美
  • PEM形燃料電池内のナノスケール水輸送現象観察と高性能電池構造の解明
    文部科学省:科学研究費補助金(基盤研究(B))
    研究期間 : 2016年 -2018年 
    代表者 : 近久 武美, 田部 豊, 大島 伸行
  • 大規模高効率化のためのレドックスフロー電池活物質輸送現象の解明
    文部科学省:科学研究費補助金(基盤研究(C))
    研究期間 : 2014年 -2016年 
    代表者 : 田部 豊
  • 凍結固定化法による固体高分子形燃料電池内の反応および気液輸送機構の解明
    文部科学省:科学研究費補助金(基盤研究(B))
    研究期間 : 2012年 -2014年 
    代表者 : 近久 武美, 田部 豊, 鈴木 研悟
  • 文部科学省:科学研究費補助金(若手研究(A))
    研究期間 : 2011年 -2013年 
    代表者 : 田部 豊
  • 文部科学省:科学研究費補助金(基盤研究(B))
    研究期間 : 2009年 -2011年 
    代表者 : 近久 武美, 田部 豊
     
    本研究は、内部現象観察と電流密度分布の同時計測、内部水分状態の瞬時凍結法を用いた観察、ならびに並列演算可能な高密度比対応LBM法により、燃料電池内の気液輸送現象について解明することを目的としたものである。本年度の研究により、下記の知見を得た:(1)これまで拡散層の繊維方向を異方化することにより電池性能を向上できることが示されていたが、リブ下の凝縮水が繊維に沿って円滑に排出されることが主因であることが確認された。(2)金属製多孔体セパレータは良好なフラッディング特性を有する一方、ドライアウトしやすい特徴がある。このドライアウトは多孔構造による熱伝導性の低下によるものであることを明らかにし、次いで接触熱抵抗の度合いや空隙率による熱伝導性の変化特性について解析を行った。(3)凝縮水の凍結固定化観察実験から、拡散層にあるMPL層は触媒層と拡散層の界面に凝縮水が滞留するのを抑制する効果を持ち、これが電池性能を良好に保つ要因であることが明らかとなった。(4)低温起動時に凍結・運転不能となった電池を常温に戻して運転した場合には、性能がなかなか回復しないことがあるが、これは触媒層とMPL層に形成された融解水によることが明らかとなった。(5)Cryo SEMを用いた観察から、酸素濃度や電流密度によって触媒層内の凍結層成長方向が異なる様子が観察され、この現象をプロトンと酸素の供給バランスによるこ...
  • 文部科学省:科学研究費補助金(若手研究(B))
    研究期間 : 2009年 -2010年 
    代表者 : 田部 豊
     
    固体高分子形燃料電池において、複雑な電池構造内の三次元解析を可能とすることにより二相流動挙動を明らかにするとともに、最適な電池構造の提案までを目指し、格子ボルツマン解析コードの大規模・高速化を行なった。さらに本コードを用い、ガス拡散層の濡れ性が凝縮水排出挙動に及ぼす影響を明らかにするとともに、リブに異なる濡れ性を与えることで、ガス拡散層内の排水に有利な電池構造が実現可能であることを示した。
  • 文部科学省:科学研究費補助金(若手研究(B))
    研究期間 : 2007年 -2008年 
    代表者 : 田部 豊
     
    白金の高効率利用に適した触媒層を明らかにすることを目的として、3相界面モデルおよび触媒層モデルを作成し解析を行った。さらに異なる高分子電解質を用いて模擬触媒層を作成し簡易実験を行った。これより、高分子電解質量、空隙率などの触媒層構造が電池性能に及ぼす影響を定量的に明らかにするとともに、高分子電解質中への酸素の溶解度上昇が電池性能向上に著しく寄与し、少ない白金担持量でも高い電池性能を得られる可能性があることを示した。
  • 文部科学省:科学研究費補助金(基盤研究(B))
    研究期間 : 2005年 -2007年 
    代表者 : 近久 武美, 田部 豊, 菊田 和重
     
    セパレータ流路形状および拡散層(GDL)の空隙率や繊維構造等が電池性能に対して及ぼす影響について研究を行い、前年度においてガスが拡散層下層に潜り込むような現象仮説を提案した。今年度はこの仮設の検証を目的として、電池内の気体流動分布計測や電流密度分布計測を行った。その結果、GDL面内をガスが流動する可能性は低いが、触媒層近傍の凝縮水の排出には不安定な現象があり、これが上記仮説に類似した現象を生じさせているものと推察された。本現象は、凝縮水を適切に排出する手がかりを含んでおり、良好な電池性能を得るための知見を得た。次に、低温起動特性を調べるとともに電池内の凍結現象を把握することを目的として、温度条件と起動特性に関する実験、ならびに凍結部の実体顕微鏡観察を行った。その結果、起動初期の電解質膜内への生成水逆拡散特性およびその後の凍結にいたる現象を明らかにすることができた。また、困難な電池内の氷結部写真撮影を可能とする技術を確立することができた。さらに本手法を用いて、凍結が主として触媒層とMPL層の間で生じており、またリブ下に比べてチャネル下により多くの氷層が形成されていることが示唆された。一方、格子ボルツマン法をベースとして、凝縮水挙動の先駆的な数値シミュレーション法の開発を行い、撥水特性や多孔質孔径が凝縮水の排出に及ぼす影響を解析した。以上、GDL内の気液移動特性および低温起動時の...
  • 文部科学省:科学研究費補助金(若手研究(B))
    研究期間 : 2005年 -2006年 
    代表者 : 田部 豊
     
    氷点下での固体高分子形燃料電池の起動特性に及ぼす起動前残留水分量ならびに運転条件の影響を実験的に明らかにするとともに、電池内の凍結機構に関する考察を行った。得られた主な知見は以下の通りである。1.セル内水分量がある程度以上ある場合には、冷却中に凍結が起り、低温起動時問が極端に短くなる。ここで、冷却中の凍結は、赤外線サーモグラフィーによる熱画像、またはセル抵抗の変化から検地することが可能である。本実験では冷却中に凍結が起こる水分量の閾値は約1mg/cm^2であった。このことより、低温起動においてはその停止条件、すなわち運転停止後のセル内の水分管理が重要であると言える。2.低温起動から生成水凍結開始までの時間は拡散層の構造の違いによる影響を受け、起動温度-10℃程度では、凝縮水圧力及び温度が高い触媒層近傍に生成水を溜め込みやすいカーボンペーパーのほうが、生成水が拡散層側へ移動しやすいカーボンクロスに比べて生成水の凍結が遅くなる傾向があった。これは、圧力および温度が高い凝縮水が過冷却状態で保持され易いためと考えられる。一方、起動温度-20℃では、カーボンペーパーとカーボンクロスの凍結開始までの時間に及ぼす影響は小さくなった。これは、より低温であることでペーパーにおいても過冷却がほとんど起こらなくなったためと考えられる。3.凝縮水が、MEA-GDL界面に貯留する場合には上述した理由で...

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    開講年度 : 2021年
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    キーワード : Energy, Renewable Energy, Environment, Economy, Policy
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    開講年度 : 2021年
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