• 한국수소및신에너지학회논문집
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• 제34권3호
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• pp.283-291
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• 2023

The physical properties were analyzed for four gas diffusion layers, and gas diffusion electrodes (GDEs) for the cathode of high-temperature polymer electrolyte membrane fuel cell were fabricated through bar coating with three binder to carbon (B/C) ratios. Among them, The GDE from JNT30-A6P showed a significant change in secondary pore volume at a B/C ratio of 0.31, which had the largest pore volume among all GDEs. In the polarization curve, JNT30-A6P GDE showed the best membrane electrode assembly (MEA) performance with a peak power density of 384 mW/cm² at a a B/C ratio of 0.31. From the distribution of relaxation time analysis, the peak 1 corresponding to mass transfer resistance of oxygen reduction reaction (ORR) was significantly reduced in the JNT30-A6P GDE. This is the result that when the binder content decreased, the volume of the secondary pore increased, and the mass transfer resistance of ORR decreased, which played an essential role in the MEA performance.

• 한국수소및신에너지학회논문집
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• 제34권2호
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• pp.196-204
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• 2023

This study performed the numerical analysis of the internal flow phenomena of 1 kWe-class solid oxide fuel cell (SOFC) stacks with internal manifold type and planar cells using commercial computational fluid dynamics (CFD) software, Star-CCM+. In particular, the locations where the turbulent phenomena occur inside the SOFC stack were investigated. In addition, the laminar flow model and the standard k-ε turbulent model were used to calculate the SOFC stack, separately. And, the calculation results of both laminar and turbulent models were compared. The calculation results showed that turbulent phenomena occurred mainly in the cathode flow. Especially, the turbulent phenomena were found in the cathode inlet/outlet region, and local turbulence occurred in the end plate near the inlet pipe.

• 한국태양에너지학회 논문집
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• 제32권5호
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• pp.118-123
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• 2012

Water balance has a significant impact on the overall fuel cell performance. Maintenance of proper water management should provide an adequate membrane hydration and avoidance of water flooding in the catalyst layer and gas diffusion layer. Considering the important of advanced water management in PEM fuel cell, this study proposes a simple one dimensional water transportation model of PEM fuel cell for use in a dynamic condition. The model has been created by assumption that the output is the water liquid saturation difference. The liquid saturation change is the total difference between the additional water and the removal water on the system. The water addition is obtained from fuel cell reaction and the electro osmotic drag. The water removal is obtained from capillary transport and evaporation process. The result shows that the capillary water transport of low temperature fuel cell is high because the evaporation rate is low.

• 한국표면공학회지
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• 제30권5호
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• pp.333-346
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• 1997

Plasma spray processes for functional coatings of tubular SOFC ( Soild oxide Fuel Cell).consisting of air electrode, oxide electrolyte, an fuel electrode, are optimized by fully saturated fractional factorial testing. Material and electric characteristics of each coating are analtsed by the implementation of SEM and optical microscope for evaluating microstructure and porosity, X-ray diffraction method for investigating compositional change between raw powder and sprayed coating, and Van der Pauw method for measuring electrical conductivity. LSM ($La_{0.65}Sr_{0.35}MnO_3$air electrode and Ni-YSL fuel electrode coatings have porosities of around 23~30% sufficient for effective fuel and oxidant gas supply to electrochemical reaction interfaces and electrical conductivities of around 90 S/cm and 1000 S/cm, respectively, enough for acting as current collecting electrodes. YSZ($ZrO_2-8mol%Y_2O_3$) electrolyte film has a high ionic conductivities of 0.05~0.07 S/cm at $1000^{\circ}C$ in air atmosphere, but appears to be somewhat too porous to reduce the thickness. for enhancing the cell efficiency. A unit tubular SOFC has beem fabricated by the optimized plasma spray processes for each functional coating and the cell. Its electrochemical chracteristics are investigated by measuring voltage-current and power density with variation of operationg temperature, radio of fuel to air gas flowrates, and total gas flowrate of reactants.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.105-108
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• 2007

Fuel cell with high electric efficiency has many probabilities of commercial use. Especially, proton exchange membrane fuel cell (PEMFC) which is a low temperature fuel cell and has less influence on $CO_2$ concentration is considered the power generation system of small building and household. We calculated the optimal operational plans of 1 kW household PEMFC power system based on the daily electricity and heat demand patterns of Japan and Korea. Calculated results show that the economic feasibility of PEMFC power system is very sensitive to the cost policy of electricity and natural gas.

• 한국유체기계학회 논문집
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• 제11권1호
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• pp.33-39
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• 2008

Hybrid power generation systems combining a solid oxide fuel cell and a gas turbine is promising due to their high efficiency. In the pressurized hybrid system, the operating condition of the gas turbine may play a critical role in designing the hybrid system. In particular, prevention of surge of the compressor can be a critical issue. The existence of fuel cell between the compressor and the turbine may cause an additional pressure loss and thus compressor operating points tend to approach the surge if the original turbine inlet temperature is pursued. In this study, bypassing some of the turbine inlet gas directly to the turbine exit side is simulated. Its effects on suppressing the surge problem and change in performance characteristics are discussed.

• 대한기계학회논문집B
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• 제30권12호
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• pp.1228-1235
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• 2006

PEMFC(Proton Exchange Membrane Fuel Cell) is a low temperature fuel cell and has many probabilities of commercial use. However, water management is one of the serious technical problems for commercialization. It is necessary to understand the relationship between operation conditions and water behavior in PEMFC channel because it affects fuel cell performance. In this paper, the distribution of current density according to inlet humidity condition is mainly observed and discussed. If the anode inlet is well humidified, electro-osmotic drag is very active. For this reason, current density is very high at inlet side and the distribution is non-uniform.

• 한국수소및신에너지학회논문집
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• 제25권6호
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• pp.620-628
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• 2014

Direct Carbon Fuel Cell(DCFC) is one of new power generation that the chemical energy of solid carbon can be converted into electrical energy directly. At the high temperature, the electrochemical reaction of the carbon takes place and the carbon reacts with oxygen to produce carbon dioxide as followed overall reaction ($C+O_2{\rightarrow}CO_2$). However, in case of using the raw coals as a fuel of DCFC, the volatile matter containing carbon, hydrogen, and oxygen produces at operating temperature. In this study, the electrochemical reaction of Adaro coal was compared with Graphite. This work focused on the electrochemical reaction of two kinds of solid carbon by Electrochemical Impedance Spectroscopy(EIS). The EIS results were estimated by equivalent circuit analysis. The constant phase element(CPE) was applied in Randle circuit to explain an electrode and fuel interface. The correlation between the fuel characteristic and electrochemical results was discussed by elements of equivalent circuit of each fuel.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.85.2-85.2
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• 2010

There is widespread effort to develop polymer membranes in place of Nafion for high temperature polymer electrolyte membrane fuel cell(PEMFC). In our study, SiO2 membranes are arranged by electrospinning method. For impregnation solution, the modified sulfonated poly(ether ether ketone)(SPEEK) polymer is prepared from sulfonation, sulfochlorination, partial reduction and lithiation reaction. The modified polymer is cross-linked with 1,4-diiodobetane in NMP solvent and then blended with Heteropoly acid(HPA). The characterization of membranes is confimed by FT-IR, Thermogravimetry(TGA), water uptake test and single cell performance test for PEMFC, etc. The composite membrane shows satisfactory thermal and mechanical properties. Beside, The membrane exhibits good ion exchange capacity and high proton conductivity. As a result, The composite membrane is promising as an alternative membrane in high temperature PEMFC.

• Macromolecular Research
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• 제14권4호
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• pp.438-442
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• 2006

Novel sulfonated poly(aryl ether ketones) containing benzoxazole were directly synthesized by aromatic nucleophilic polycondensation using various ratios of 2,2'-bi[2-( 4-flurophenyl)benzoxazol-6-yl]hexafluoropropane to sodium 5,5'-carbonylbis(2-fluorobenzenesulfonate). The copolymers were soluble in polar aprotic solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, and N,N-dimethylformamide at a relatively high solid composition (>15 wt%) and formed tough, flexible and transparent membranes. The membranes exhibited a degradation temperature of above $290^{\circ}C$. The exact dissolution times of these membranes at $80^{\circ}C$ in Fenton's reagent (3 wt% $H_2O_2$ containing 2 ppm $FeSO_4$) were undetectable, confirming their excellent chemical stability in fuel cell application. The membranes showed a moderate increase in water uptake with respect to increasing temperature. The proton conductivities of the membranes were dependent on the composition and ranged from $1.10{\times}10^{-2}$ to $5.50{\times}10^{-2}Scm^{-1}$ at $80^{\circ}C$ and 95% relative humidity (RH). At $120^{\circ}C$ without externally humidified conditions, the conductivities increased above $10^{-2}Scm^{-1}$ with respect to increasing benzoxazole content, which suggested that the benzoxazole moieties contributed to the proton conduction.