Electrochemistry
Online ISSN : 2186-2451
Print ISSN : 1344-3542
ISSN-L : 1344-3542
Volume 73 , Issue 3
Showing 1-18 articles out of 18 articles from the selected issue
Preface
Articles
  • Hisashi MINAKUCHL, Yuzoh YAMASHITA, Yasunori OKANO, Masao SUDOH, Shuuh ...
    2005 Volume 73 Issue 3 Pages 182-188
    Published: March 05, 2005
    Released: June 01, 2019
    JOURNALS OPEN ACCESS

    A numerical simulation study of fluid flow, heat and mass transfer in a proton exchange membrane fuel cell (PEMFC) was performed. The three-dimensional continuity, momentum, and mass transport equations were discretized by the finite volume technique on the staggered mesh and solved by the SIMPLE algorism. The electrochemical reaction at the catalyst layer was considered in the model. Effects of flow rate, flow field, and channel configuration on current density distribution were examined to optimize the fuel cell design for high-energy efficiency and high power density performance. Simulation results show that insufficient inlet gas flow rate and low humidity would reduce the performance of the fuel cell. The effect of channel depth on current density and flow field was also presented.

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  • Jung Min SONG, Hiroyuki UCHIDA, Masahiro WATANABE
    2005 Volume 73 Issue 3 Pages 189-193
    Published: March 05, 2005
    Released: June 01, 2019
    JOURNALS OPEN ACCESS

    Gas diffusion electrodes consisting of three layers, i.e., Pt/C catalyst layer (CL), hydrophobic gas-diffusion layer (GDL) and carbon backing layer (CBL), for polymer electrolyte fuel cells (PEFC) were investigated to clarify the relation between the electrochemical performance and the microstructure. We focused on effects of the GDL coating and the content of wet-proofing material (tetrafluoroethylene-hexafluoropropylene, FEP) in the CBL on the electrode performances with the constant composition of the CL. It was found that the hydrophobic GDL is effective to enhance the O2 diffusivity and the catalyst utilization. A high performance due to high O2 diffusivity was observed for the electrode by using the CBL without any FEP treatment at a relatively low air utilization operation. In contrast, the FEP treatment was found to be effective for the application to, for example, co-generation type fuel cells, which require the operation at relatively high potential and high utilization of air, e.g., 0.8 V and 40%.

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  • Hirofumi SUMI, Yasunobu MIZUTANI, Makoto TAKAHASHI, Makoto SAKURAI, Ma ...
    2005 Volume 73 Issue 3 Pages 194-198
    Published: March 05, 2005
    Released: June 01, 2019
    JOURNALS OPEN ACCESS

    Dependence of water partial pressure (PH2O) on the protonic conductivities of phosphate glasses made by a condensation-polymerization process below liquidus temperature has been investigated. Protonic conductivities of Sr-Ba-Pb + W-phosphate glass at 373 K were 4×10-5 and 6×10-4 S/cm, at PH2O = 0.035 and 0.485 atm, respectively. The PH2O dependence of conductivity for this glass is lower than that for Nafion. When operating under a non-humidified condition, the conductivity remains unchanged with time, and the fuel cell using the glass electrolyte was able to generate power continuously. The phosphate glass is one of the new candidate materials for electrolyte used in fuel cells.

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