• Transactions of the Korean hydrogen and new energy society
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• v.22 no.1
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• pp.69-76
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• 2011

PEMFC (polymer electrolyte membrane fuel cell) is device that generates electricity from hydrogen. It is one of the subjects related to renewable energy and various research has been conducted on the PEMFC. PEMFC has low operating temperature and high efficiency among fuel cells, and is given attention as means for automobile and domestic use. Analysis of flow field pattern in supplying hydrogen and oxygen is part of the research to increase PEMFC efficiency. In this study, separation plate currently used in PEMFC is transformed to wave shape and mass transfer characteristics in the channel is examined through numerical and experimental analysis. Wave shape separation plate yielded 18% increase of efficiency compared to separation plate used in normal channel. And improvements in mass transfer characteristics were verified.

• Transactions of the Korean hydrogen and new energy society
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• v.30 no.6
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• pp.601-607
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• 2019

Ammonia would be formed in natural gas containing small amount of nitrogen reforming process in the process natural gas, which might damage the Pt catalyst and Prox catalyst. In the article, the effect of nitrogen contents on the formation of ammonia in the reforming process has been studied. In the experiments, Ru based and Ni based catalysts were used and the concentration of ammonia in the reformate gas at various gas hourly space velocity was measured. Experimental result shows that relatively higher ammonia concentration was measured with Ru based catalyst than with Ni based catalyst. It also shows that the concentration of ammonia increased rapidly after most of the methane converted into hydrogen. Based on the experimental results to reduce ammonia concentration it might be better to finish methane conversion at the exit position of the reforming reactor to minimize the contact time of catalyst and nitrogen with high concentration of hydrogen.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.110-112
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• 2006

Membrane electrode assembly (MEA) for polymer electrolyte fuel cell (PEFC) are commonly prepared in the research laboratory by spraying, screen-printing and brushing catalyst slurry onto membrane or other support material like carbon paper or polyimide film in a batch style. These hand applications of the catalyst slurry are painstaking process with respect to precision of catalyst loading and reproducibility. It has been generally mentioned that the adoption of continuous process is very helpful to develop the reliable product. In the present work, we report the results of using continuous type coater with doctor-blade to coat catalyst slurry for preparing the MEA catalyst layers In a faster and highly reproducible fashion. We show that while expectedly faster than batch style, the machine coater requires the use of slurry of appropriate composition and a properly selected transfer decal material in order to achieve superior MEA plat lnw loading reproducibility. To make highly viscous catalyst slurry that is imperative for using coater, we use 40wt.% Nafion solution and minimize the content of organic solvent. And the choice of proper high surface area catalyst is important in the viewpoint of making well-dispersed slurry. After catalyst coating onto the support material, we transferred the catalyst layer to both sides of Nafion membrane by hot-pressing In this case, the degree of transfer was Influenced by hot-pressing condition including temperature, pressure, and time. To compare the transferring ability, we compared so many films and detaching papers. And among the support, polyethylene terephthalate(PET) film shows the prominent result.

• Journal of Energy Engineering
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• v.19 no.2
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• pp.73-80
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• 2010

A solid oxide fuel cells(SOFC) is a clean energy technology which directly converts chemical energy to electric energy. When the SOFC is used in cogeneration then the efficiency can reach higher than 80%. Also, it has flexibility in using various fuels like natural gases and bio gases, so it has an advantage over polymer electrolyte membrane fuel cells in terms of fuel selection. A typical cathode material of the SOFC in conjunction with yttria stabilized zirconia(YSZ) electrolyte is still Sr-doped $LaMnO_3$(LSM). Recently, application of mixed electronic and ionic conducting perovskites such as Sr-doped $LaCoO_3$(LSCo), $LaFeO_3$(LSF), and $LaFe_{0.8}Co_{0.2}O_3$(LSCF) has drawn much attention because these materials exhibit lower electrode impedance than LSM. However, chemical reaction occurs at the manufacturing temperature of the cathode when these materials directly contact with YSZ. In addition, thermal expansion coefficient(TEC) mismatch with YSZ is also a significant issue. It is important, therefore, to develop cathode materials with good chemical stability and matched TEC with the SOFC electrolyte, as well as with high electrochemical activity.

• Korean Chemical Engineering Research
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• v.45 no.6
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• pp.656-662
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• 2007

Fuel reformer using plasma and shift reactor for CO oxidation were designed and manufactured as $H_2$ supply device to operate a polymer electrolyte membrane fuel cell (PEMFC). $H_2$ selectivity was increased by non-thermal plasma reformer using GlidArc discharge with Ni catalyst simultaneously. Shift reactor was consisted of steam generator, low temperature shifter, high temperature shifter and preferential oxidation reactor. Parametric screening studies of fuel reformer were conducted, in which there were the variations of the catalyst temperature, gas component ratio, total gas ratio and input power. and parametric screening studies of shift reactor were conducted, in which there were the variations of the air flow rate, stema flow rate and temperature. When the $O_2/C$ ratio was 0.64, total gas flow rate was 14.2 l/min, catalytic reactor temperature was $672^{\circ}C$ and input power 1.1 kJ/L, the production of $H_2$ was maximized 41.1%. And $CH_4$ conversion rate, $H_2$ yield and reformer energy density were 88.7%, 54% and 35.2% respectively. When the $O_2/C$ ratio was 0.3 in the PrOx reactor, steam flow ratio was 2.8 in the HTS, and temperature were 475, 314, 260, $235^{\circ}C$ in the HTS, LTS, PrOx, the conversion of CO was optimized conditions of shift reactor using simulated reformate gas. Preheat time of the reactor using plasma was 30 min, component of reformed gas from shift reactor were $H_2$ 38%, CO<10 ppm, $N_2$ 36%, $CO_2$ 21% and $CH_4$ 4%.