• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.8 s.251
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• pp.731-740
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• 2006

The solid oxide fuel cell (SOFC) is expected to be a candidate for distributed power sources in the next generation, due to its high efficiency and high-temperature waste heat utilization. In this study, the 5-cell SOFC stack was operated with pure hydrogen or reformed gas at anode side and air at cathode side. When stack was operated with diesel and methane ATR reformer, the influence of the $H_2O/C,\;O_2/C$ and GHSV on performance of stacks have been investigated. The result shows that the cell voltage was decreased with the increase of $H_2O/C$ and $O_2/C$ due to the partial pressure of fuel and water, and cell voltage was more sensitive to $O_2/C$ than $H_2O/C$. Next, the dynamic model of SOFC system included with ATR reformer was established and compared with experimental data. Based on dynamic model, the operation strategy to optimize SOFC-Reformer system was suggested and simulated.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1740-1745
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• 2004

A simplified resistor network model for electrical and mass transport in anode-supported planar solid oxide fuel cell (SOFC) was constructed in order to investigate the effect of interconnect rib geometry on the cell performance. For accurate potential calculation, activation and concentration over-potentials at the electrode/electrolyte interfaces were fully considered in this calculation. When contact resistance was not considered, the optimum interconnect rib length were calculated to be $0.1{\sim}0.2$ mm for 2 mm half unit cell for given operation conditions and properties. However, with realistic contact resistance, the interconnect rib length should be increased to provide larger contact area and thus to obtain better performance.

• Journal of Energy Engineering
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• v.27 no.4
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• pp.1-12
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• 2018

The code and standards related to fuel cells were analyzed to derive the SOFC(Solid Oxide Fuel Cell) stack safety performance evaluation items and evaluation methode. Safety performance evluation of the SOFC stack was tested by quoting derived test items. The stack used in the test is an anode-supported type 2 Cell stack (Active surface area : 220cm) manufactured by MICO Inc, and SOFC stack safety performance evaluation system used for the test is self-manufactured. We conducted a leakage test, current voltage characteristic test, rated output test, and power response characteristics test. In the safety performance evaluation test, the stack showed no gas leakage, the maximum output and rated output was recorded to 65.6 W(1.41 V, 46.5 A, $422mA/cm^2$), 62.3 W(1.57 V, 40 A, $363mA/cm^2$). In the power response characteristics test verified that the output is kept stable within two seconds. At the maximum load (40 A) and the minimum load (8 A), the output was recorded 62 W and 16W in $750^{\circ}C$. This study will contribute to the universalization and to provide much safe environment of operating the solid oxide fuel cell system.

• Journal of Hydrogen and New Energy
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• v.21 no.3
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• pp.214-219
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• 2010

In this study, we fabricated tubular ceramic support for segmented-in-series solid oxide fuel cell (SOFC) by using CSZ(CaO-stabilized $ZrO_2$) as main material and activated carbon as pore former. Thermal expansion properties of ceramic support with different amounts of activated carbon were analyzed by using dilatometer to decide a suitable sintering temperature. The tubular ceramic supports with different amounts of activated carbon (5, 10, 15wt.%) were fabricated by the extrusion technique. After sintering at $1100^{\circ}C$ and $1400^{\circ}C$ for 5h., cross section and surface morphology of tubular ceramic support were analyzed by using SEM image. Also, the porosity, mechanical property, gas permeability of tubular ceramic supports was measured. Based on these results, we established the suitable fabrication technique of tubular ceramic support for segmented-in-series SOFC.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.5-8
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• 2008

SOFC (Solid oxide fuel cell) has an advantage in the term of fuel flexibility, comparing with other kinds of fuel cells. In SOFC and fuel reformer cooperation system, the reformate gas with the various $H_2$/CO ratios is delivered into the anode of SOFC. In this situation, electrochemical oxidation reactions of the reformate gas in the anode are complex and competitive. In this paper, the effects of the composition of $H_2$ and CO on the overall electrochemical oxidation at Ni-YSZ anode are studied by testing the open circuit voltage (OCV) and current-voltage characteristics of single cells.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.379-381
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• 2009

The simulation model for metal-supported Solid Oxide Fuel Cell(SOFC) is developed in this study. Open circuit voltage is calculated using Nernst equation and Gibbs free energy is required by thermodynamic. The exchange current densities are compared with experimental results since exchange current density is most effective factor for the activation loss. Liu's study is used for the exchange current density of cathode, BSCF, and Koide's result is applied for the exchange current density of anode, Ni/YSZ. For the ohmic loss, ionic conductivity of YSZ is described from Kilner's mode and the data are compared with Wanzenberg's experimental data. Diffusivity is an important factor for the mass transfer through the porous medium. Both binary diffusion and Knudsen diffusion are considered as the diffusion mechanism. For validation, simulation results at this work are compared with our experimental results.

• Journal of the Korean Electrochemical Society
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• v.10 no.2
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• pp.110-115
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• 2007

Solid oxide fuel cell(SOFC) has high fuel flexibility due to its high operating temperatures. Hydrocarbonaceous fuels such as diesel has several advantages such as high energy density and established infrastructure for fuel cell applications. However diesel reforming has technical problems like coke formation in a reactor, which results in catastrophic failure of whole system. Performance degradation of diesel autothermal reforming (ATR) leads to increase of undesirable hydrocarbons at reformed gases and subsequently degrades SOFC performance. In this study, we investigate the degradation of SOFC performance(OCV, open circuit voltage) under hydrocarbon(n-Butane) feeds and characteristics of diesel performing under various ratios of reactants($H_2O/C,\;O_2/C$ molar ratios) for improvement of SOFC performance. Especially we achieved relatively high performance of diesel ATR under $H_2O/C=0.8,\;O_2/C=3$ condition.

• Korean Journal of Materials Research
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• v.4 no.7
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• pp.741-749
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• 1994

The planar solid oxide fuel cell(SOFC) contains several ceramic materials depending on its structure and has rdfractory metal parts for manifolds, shrouds and current leads. Among ceramic materials for planar SOFC, joining of lanthanum chromite separator and yttria stabilized zirconia(YSZ) electoyte in planar SOFC stack to give strong gas tight seals is necessary for satisfactory operation and high performance. Nevertheless, for planar SOFC/sub s/, how to seal the cell stack and gas manifold remains as one of the unsolved problems. Therefore, in this study. we investigated the joining of sintered lanthanum chromite and YSZ pellets using unsintered lanthanum chromite green films as sealent. Scanning electron microscopy(SEM) and energy dispersive X-ray analysis(EDX) revealed that Ca in the sealing material diffused and dissolved into YSZ and sintered lanthanum chromite, and unsintered lanthanum chromite green films reacted with YSZ to from a new phase at the interface. Also, the densification of unsintered lanthanum chromite green films was inpeded by the Ca migration.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.601-602
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• 2010

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.273-276
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• 2005

Performance analysis of a solid oxide fuel cell/micro gas turbine hybrid system is conducted at design-point and part-load conditions and its results are discussed in this study. With detailed considerations of the heat and mass transfer phenomena along various flow streams of the SOFC, the analysis based on a quasi-2D model reasonably predicts its performance at the design-point operating conditions. In case of part-load operations, performance of the hybrid system to three different operation modes(fuel only control, speed control, and VIGV control) is compared. It is found that the simultaneous control of both supplied fuel and air to the system with a variable MGT rotational speed mode is the optimum choice for the high performance operation. And then, the dynamic characteristics of a solid oxide fuel cell are briefly introduced.