• 제목/요약/키워드: Nernst Diffusion Layer

검색결과 2건 처리시간 0.015초

회전하는 원형단면 실린더 주위의 난류유동 물질전달에 대한 (Direct Numerical Simulation of Mass Transfer in Turbulent Flow Around a Rotating Circular Cylinder (II) - Effect of Schmidt Number -)

  • 황종연;양경수
    • 대한기계학회논문집B
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    • 제29권7호
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    • pp.846-853
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    • 2005
  • In this paper, mass transfer in turbulent flow around a rotating circular cylinder is investigated by Direct Numerical Simulation for Schmidt numbers Sc=1 and 1670. Correlation between Sherwood and Reynolds number predicted agrees well with other experimental results over both Sc. Reynolds analogy identified at Sc=1 definitely causes a strong correlation between concentration fluctuation and streamwise velocity. For Sc=1670, it is found that positive small values of concentration fluctuations are observed more frequently than the case of Sc=1 particularly out of the range of Nernst diffusion layer in the viscous sub-layer. This fact is fully confirmed by detailed statistical study using a probability density function of concentration fluctuations.

Variation of Oxygen Nonstoichiometry of Porous $La_{0.6}Ca_{0.4}MnO_{3-{\delta}}$ SOFC-Cathode under Polarization

  • Mizusaki, Junichiro;Harita, Hideki;Mori, Naoya;Dokiya, Masayuki;Tagawa, Hiroaki
    • The Korean Journal of Ceramics
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    • 제6권2호
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    • pp.177-182
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    • 2000
  • At the porous $La_{0.6}Ca_{0.4}MnO_{3-{\delta}}$(LCM)/YSZ electrodes of solid oxide fuel cells (SOFC), the electrochemical redox reaction of oxygen proceeds via the triple boundary (TPB) of gas/LCM/YSZ. The surface diffusion of adsorbed oxygen on LCM has been proposed as the rate determining process, assuming the gradient of oxygen chemical potential from the outer surface of porous layer to TPB. Along with the formation of this gradient, oxygen nonstoichiometry in the bulk of LCM may varies. In this paper, an electrochemical technique was described precisely to determine the variation of oxygen content in LCM of porous LCM/YSZ under polarization. It was shown that the oxygen potential in LCM layer under large cathodic polarization is much lower than that in the gas phase, being determined from the electrode potential and Nernst equation.

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