• 한국세라믹학회지
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• 제42권12호
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• pp.777-786
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• 2005

The Solid Oxide Fuel Cell (SOFC) is an electrochemical device to convert chemical energy of a fuel into electricity at temperatures from about 600 to $1000^{\circ}C$. The SOFC offers certain advantages over lower temperature fuel cells, notably its ability to use CO as a fuel rather than being poisoned by it, and high grade exhaust heat for combined heat and power, or combined cycle gas turbine applications. This paper reviews the operating principle, materials for different cell and stack components, cell designs, and applications of SOFCs. Among all designs of Solid Oxide Fuel Cells (SOFCs), the most progress has been achieved with the tubular design. However, the electrical resistance of tubular SOFCs is high, and specific power output $(W/cm^2)$ and volumetric power density $(W/cm^3)$ low. Planar SOFCs, in contrast, are capable of achieving very high power densities.

• Journal of Electrical Engineering and information Science
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• 제2권4호
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• pp.66-71
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• 1997

The dielectrophoretic(DEP) force acting on a cell in an electric field is experimentally determined. A cell is accelerated by the DEP force in an electric field generated between micro planar electrodes. the position of the cell is measured and the velocity and acceleration of the cell are calculated based on the measured position data. The DE force is determined from the motion equation of a moving cell in suspension. The electrode structure is fabricated by micromachining technology and the height of electrodes is 1 $\mu\textrm{m}$. Radish cell and yeast are used in th experiments. In the case of radish cell, the DEP force increases as voltage or frequency(1MHz∼3MHz) increases. The voltage dependence can be explained that the DEP force increases when ▽│E│$^2$increases. The frequency dependence means that Re[x\ulcorner] of radish cell is maximized in a certain frequency. In the case of yeast, the DEP force increases only as voltage increases. The reason for the voltage dependence is the same with the case of radish. The DEP force increases only as voltage increases. The reason for the voltage dependence is the same with the case of radish. The DEP force on a yeast does not vary when the frequency varies from 1MHz to 3MHz. This result coincides with the fact that the value of calculated Re[x\ulcorner] is constant in the test frequency range.

• 신재생에너지
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• 제3권3호
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• pp.5-13
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• 2007

Stacks of solid oxide fuel cell with 1kW max power performance were designed on planar type employing anode-supported cells and metallic interconnects. The stacks composed of 3-cells, 8-cells, and 16-cells were fabricated and tested in serials by using anode-supported cells purchased from Indec, and sealants/interconnects prepared at RIST. In the performance test of the final 16-cells stack, OCV was recorded to be 16.7V. The peak power and the power density showed 1 kW, $0.77W/cm^2$ at $820^{\circ}C$, respectively. In addition, the long-term degradation rate of the power exhibited 2.25 % during 500h at $750^{\circ}C$.

• 한국세라믹학회지
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• 제51권4호
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• pp.289-294
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• 2014

The stability of a solid oxide fuel cell (SOFC) stack is strongly dependent on the magnitude and profile of the internal chemical potential of the solid electrolyte. If the internal partial pressure is too high, the electrolyte can be delaminated from the electrodes. The formation of high internal pressure is attributed to a negative cell voltage, and this phenomenon can occur in a bad cell (with higher resistance) in a stack. This fact implies that the internal chemical potential plays an important role in determining the lifetime of a stack. In the present work, we fabricate planar type anode-supported cells ($25cm^2$) with a bi-layer electrolyte (with locally increased electronic conduction at the anode side) to prevent high internal pressure, and we test the fabricated cells under a negative voltage condition. The results indicate that the addition of electronic conduction in the electrolyte can effectively depress internal pressure and improve the cell stability.

• 한국수소및신에너지학회논문집
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• 제20권4호
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• pp.300-308
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• 2009

In a pursuit of the development of alternative mobile power sources with a high energy density, a planar and air-breathing PEMFCs with a new type of hydrogen cartridge which uses onsite $H_2$ generated from sodium borohydride ($NaBH_4$) hydrolysis have been investigated for use in advanced power systems. Two types of $H_2$ generation through $NaBH_4$ hydrolysis are available: (1) using organic acids such as sulphuric acid, malic acid, and sodium hydrogen carbonate in aqueous solution with solid $NaBH_4$ and (2) using solid selected catalysts such as Pt, Ru, CoB into the stabilized alkaline $NaBH_4$ solution. It might therefore be relevant at this stage to evaluate the relative competitiveness of the two methods mentioned above. The effects of flow rate of stabilized $NaBH_4$ solution, MEA (Membrane Electrode Assembly) improvement, and type and flow control of the catalytic acidic solution have been studied and the cell performances of the planar, air-breathing PEMFCs using $NaBH_4$ has been measured from aspects of power density, fuel efficiency, energy density, and fast response of cell. In our experiments, planar, air-breathing PEMFCs using $NaBH_4$ achieved to maximum power density of 128mW/$cm^2$ at 0.7V and energy efficiency of 46% and has many advantages such as low operating temperature, sustained operation at a high power density, compactness, the potential for low cost and volume, long stack life, fast star-up and suitability for discontinuous operation.

• Journal of Information Display
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• 제10권2호
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• pp.72-75
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• 2009

The Brillouin spectrum of 4'-n-pentyl-4-cyano-biphenyl (5CB) liquid crystals homogeneously confined in a planar liquid crystal (LC) cell was measured using a 6-pass tandem Fabry-Perot interferometer. By adopting a special right-angle scattering geometry, the sound velocity of 5CB was estimated from the Brillouin shift without knowing the refractive index. The sound velocity of the longitudinal wave propagating along the direction of the directors aligned parallel to the glass plates of the LC cell was 1784${\pm}$7 m/s at 300 K. The attenuation coefficient $\alpha$ was estimated to be approximately $1.9{\times}10^6m^{-1}$, which is about twice as large as that of the longitudinal sound wave propagating along the direction perpendicular to the directors. The present method may be very useful in the evaluation of the elastic properties of the materials used in display devices, whose refractive indices are not known.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 제17회 워크샵 및 추계학술대회
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• pp.648-654
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• 2005

The performance prediction of a planar-type solid oxide fuel ceil is conducted by a computational analysis. The transport processes are formulated with the help of a simplified treatment of heat generation by the electrochemical reaction. From the result of the computational analysis, it is shown that the electrochemical reaction is closely related to the transport phenomena inside a solid oxide fuel cell. Transport phenomena including heat and mass transfer have influence on the distribution of local current density and as a result, on the performance characteristics of the fuel cell. Computational analysis is also extended to the parametric study to investigate the performance behavior of the fuel cell with different amount of supplied fuel flow rates. It is also demonstrated that the mathematical formulation and computational procedures proposed in this study can be applied to prove the importance of the specific TPB(Three-Phase-Boundary) area in the manufacturing process of electrodes in a solid oxide fuel cell.

• 한국세라믹학회지
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• 제42권12호
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• pp.846-853
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• 2005

For the performance prediction of a planar-type solid oxide fuel cell, the computational analysis of transport phenomena with a simplified treatment of heat generation by the electrochemical reaction is conducted. From the result of the computational analysis, it is shown that the electrochemical reaction is closely related to the transport phenomena inside a solid oxide fuel cell. Transport phenomena including heat and mass transfer influences on the distribution of local current density and, as a result, on the performance characteristics of the fuel cell. Computational analysis is also extended to the parametric study to investigate the performance behavior of the fuel cell with different amount of supplied fuel flow rates. It is also demonstrated that the mathematical formulation and computational procedures proposed in this study can be applied to prove the importance of the specific TPB area in the manufacturing process of electrodes in solid oxide fuel cells.

• 전기화학회지
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• 제7권2호
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• pp.69-79
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• 2004

전산모사를 이용하여 특성을 정확하게 모사하기 위해서는 전지 내부에서 발생하는 다양한 물리적, 화학적 현상을 고려하여야 한다. 이를 위해, 본 연구에서는 다양한 전지 내부 현상에 대한 변수를 고려할 수 있는 전산유체 상용코드인 CFD-ACE+를 이용하여 평판형 고체산화물 연료전지의 작동 특성을 분석하였다. 단위 스택에서 발생하는 물질전달과 열전달 및 전기화학 반응에 의한 전하이동을 복합적으로 고려하여, 작동조건 하에서 각 공정적, 구조적 변수 변화에 따른 전지특성을 예측하였다. 이러한 전산모사 방법을 통하여 확산과 유동에 의한 전지 내 반응물과 생성물의 mass fraction 분포와 단위 스택의 내부 온도분포 그리고 전지 특성을 나타내는 polarization curve에 의한 고체산화물 연료 전지의 분극 특성을 정성, 정량적으로 제시하였다. 본 연구를 통해 평판형 단위 스택 내에서의 다양한 변수 변화에 따른 전지의 작동 특성에 대한 효율적 예측이 가능하였고, 고체산화물 연료전지 작동 시 발생하는 현상에 대한 전산모사 접근법을 체계적으로 제시할 수 있었다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 1996년도 재료학회 춘계학술발표회
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• pp.148-148
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• 1996