• 에너지공학
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• 제20권3호
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• pp.252-258
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• 2011

Nickel fiber mat was investigated as a potential structured catalyst for steam reforming of biogas in the temperature range of $600-700^{\circ}C$. The activity of as-received catalyst was very low owing to the smooth surface of fibers. Pretreatment of the catalyst by oxidation followed by reduction under methane partial oxidation condition significantly improved the catalytic activity, although degradation of the activity was found during the reaction due to oxidation and sintering. This deactivation was retarded by supplying additional hydrogen in the inlet gases or by coating $CeO_2$ over the catalyst surfaces.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.184-187
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• 2007

Hydrogen could be produced from any substance containing hydrogen atoms, such as water, hydrocarbon (HC) fuels, acids or bases. Hydrocarbon fuels couold be converted to hydrogen-rich gas through reforming process for hydrogen production. Even though fuel cell have high efficiency with pure hydrogen from gas tank, it is more beneficial to generate hydrogen from city gas (mainly methane) in residential application such as domestic or office environments. Thus hydrogen is generated by reforming process using hydrocarbon. Unfortunately, the reforming process for hydrogen production is accompanied with unavoidable impurities. Impurities such as CO, $CO_2$, $H_2S$, $NH_3$, and $CH_4$ in hydrogen could cause negative effects on fuel cell performance. Those effects are kinetic losses due to poisoning of electrode catalysts, ohmic losses due to proton conductivity reduction including membrane and catalyst ionomer layers, and mass transport losses due to degrading catalyst layer structure and hydrophobic property. Hydrogen produced from reformer eventually contains around 73% of $H_2$, 20% or less of $CO_2$, 5.8% of less of $N_2$, or 2% less of $CH_4$, and 10ppm or less of CO. Most impurities are removed using pressure swing adsorption (PSA) process to get high purity hydrogen. However, high purity hydrogen production requires high operation cost of reforming process. The effect of carbon dioxide on fuel cell performance was investigated in this experiment. The performance of PEM fuel cell was investigated using current vs. potential experiment, long run (10 hr) test, and electrochemical impedance measurement when the concentrations of carbon dioxide were 10%, 20% and 30%. Also, the concentration of impurity supplied to the fuel cell was verified by gas chromatography (GC).

• Korean Chemical Engineering Research
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• 제53권5호
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• pp.584-589
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• 2015

잠수함 및 수중무인체계 등의 산소희박환경에서 연료전지를 통한 효과적인 전력생산을 위해서는 높은 수소저장밀도를 갖는 수소공급원이 필요하다. 디젤연료는 액체연료로서 저장 및 공급이 용이하며, 연료전지의 연료가 되는 수소의 단위질량 및 단위부피당 저장밀도가 높은 장점을 갖고 있다. 이러한 디젤연료의 장점을 기반으로 본 연구에서는 산소희박환경에서 수소생산을 위해 디젤연료의 개질반응을 이용하였으며, 산화제로 단위부피당 산소 저장밀도가 높고 액상으로 보관이 용이한 과산화수소 수용액을 기존의 산화제인 물과 산소의 대체산화제로 이용하는 방법을 제안하였다. 과산화수소 수용액의 디젤개질 산화제로써의 특성을 파악하기 위해 물, 공기 산화제와의 비교실험을 진행하였으며, 기존의 산화제와 디젤 개질반응 시 동일한 특성을 갖는 것을 실험적으로 확인하였다. 또한 상용디젤을 연료로 온도 및 과산화수소 수용액의 농도에 따른 개질성능을 평가하였으며, 49시간의 가속 열화실험을 통하여 디젤, 과산화수소 수용액을 이용한 수소생산의 가능성을 확인하였다.

• 한국가스학회지
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• 제13권4호
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• pp.46-52
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• 2009

고유가 시대의 도래와 강화되는 배출가스 규제에 대응하기 위한 대책으로 대체에너지 엔진 및 수소연료전지와 같은 새로운 연소 및 동력 기술에 대한 관심이 증대되고 있으나, 이러한 기술의 이용은 수소제조 및 공급 기반시설 구축이 선결되어야 하며 많은 투자가 요구된다. 수소를 내연기관에 활용하는 기술은 연료의 저장과 공급, 낮은 에너지 밀도 및 연소제어 등의 어려움이 있다. 그러나 화석연료로부터 합성연료를 제조하기 위한 중간단계로 생성되는 개질가스의 이용은 내연기관으로의 실시간 수소 공급을 가능하게 하고, 소량의 수소가 혼합연료 형태로 사용됨에 따라 연소특성을 향상시킬 수 있다. 본 연구에서는 다양한 연료들의 개질 특성을 이해함과 동시에 연료 개질기의 적용가능성 여부를 판단하고자 하였다. 연료별 최대의 수소수율을 얻을 수 있는 조건에서의 열역학적 개질효율과 수소수율을 관찰하였으며, 연료와 산화제의 촉매상에서의 체류시간에 대한 영향 및 연료/산화제 비율에 변화 시 최대 수소 수율을 제시하였다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2010년 춘계학술대회논문집
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• pp.228-232
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• 2010

In this paper, various operating parameters of stream reforming process from methane in preconverter for MCFC is studied by numerical method. Commercial code is used to simulated the porous catalyst with user subroutine to model three dominant chemical reactions which are Stream Reforming(SR), Water-Gas Shift(WGS), and Direct Stram Reforming(DSR). The hydrogen production is tested with different wall temperature, Gas Hourly Space Velocity(GHSV), and different reactor shapes.

• 한국수소및신에너지학회논문집
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• 제29권1호
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• pp.11-18
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• 2018

A high efficiency integrated reforming system for improving the efficiency of the 5 kW PEMFC system used as the back up power of building was studied. The separated reforming system consisted of three parts - A steam reformer with two stage concentric circular shape, a heat exchanger type steam generator and a CO shift reactor. Temperature and steam carbon ratio (SCR) were control variables during operation. The operating conditions were optimized based on the thermal efficiency of the steam reformer as reformate gas composition changes at different temperature. In experiments, water was fully vaporized in the steam generator up to SCR 3.5 and the maximum thermal efficiency was achieved at the operating temperature around $700^{\circ}C$ in the steam reforming reactor. With the results of the separated reforming system research, we improved the shape of high efficiency integrated reformer. The performance evaluation of the integrated reformer was based on optimized operating conditions in SCR 3.5. As a result, the developed integrated reforming system maintained an efficiency of 76% and constant performance over 3,000 hours.

• Journal of Advanced Marine Engineering and Technology
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• 제35권4호
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• pp.388-396
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• 2011

온실가스 및 대기오염물질 배출 규제는 고효율 및 친환경에 적합한 새로운 선박용 동력장치의 필요성을 제기하고 있다. 최근 이와 같은 문제들을 근본적으로 해결하기 위한 지속가능한 방법으로서 연료전지를 선박의 동력발생장치로 도입하고자 하는 검토가 진행되고 있다. 본 논문은 선박용 연료전지시스템에 사용될 수 있는 최적의 연료를 파악하기 위하여 다양한 탄화수소계 및 알코올계 연료의 수증기 개질특성을 열역학적으로 검토하고 있다.

• 한국군사과학기술학회지
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• 제20권4호
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• pp.528-535
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• 2017

Fuel cells have been spotlighted in the world for being highly efficient and environmentally friendly. A hydrogen which is the fuel of fuel cell can be obtained from a number of sources. Hydrogen source for operating the polymer electrolyte membrane fuel cell(PEMFC) in the current underwater environment, such as a submarine and unmanned underwater vehicles are currently from the metal hydride cylinder. However, metal hydride has many limitations for using hydrogen carrier, such as large volume, long charging time, limited storage capacity. To solve these problems, we suggest diesel reformer for hydrogen supply source. Diesel fuel has many advantages, such as high hydrogen storage density, easy to transport and also well-infra structure. However, conventional diesel reforming system for PEMFC requires a large volume and complex CO removal system for lowering the CO level to less than 10 ppm. In addition, because the preferential oxidation(PROX) reaction is the strong exothermic reaction, cooling load is required. By changing this PROX reactor to hydrogen separation membrane, the problem from PROX reactor can be solved. This is because hydrogen separation membranes are small and permeable to pure hydrogen. In this study, we conducted the pressurized diesel reforming and water-gas shift reaction experiment for the hydrogen separation membrane application. Then, the hydrogen permeation experiments were performed using a Pd alloy membrane for the reformate gas.

• 한국수소및신에너지학회논문집
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• 제15권1호
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• pp.54-61
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• 2004

Temperature characteristics in a stack of molten carbonate fuel cell (MCFC) have been investigated with simulation based on the computational fluid dynamics (CFD) codes and experimental way. The MCFC has generally two stack structures when the natural gas is used as fuel; one is the external reforming type and the other is internal reforming type. Computer simulation at the external reforming stack suggests that the maximum temperature in the stack depends on the gas flow length. The 2 kW MCFC stack with 25 cm gas flow length showed about $675^\circ{C}$ of maximum temperature.

• 설비공학논문집
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• 제16권11호
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• pp.1021-1027
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• 2004

Design performances of various configurations of hybrid systems combining an atmospheric pressure molten carbonate fuel cell and a gas turbine have been analyzed. Two different fuel reforming methods (internal and external reforming) were considered. Influences of turbine inflow heating method, location of fuel combustor and associated component arrangements were investigated. In general, internal reforming leads to higher system efficiencies. The optimum design pressure ratio varies among different system configurations. In particular, the design point selection is closely related to the allowable turbine inlet temperature. Configurations with direct heating of turbine inlet flow may realize both higher efficiency and higher specific power than those with indirect heating.