• Transactions of the Korean hydrogen and new energy society
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• v.33 no.6
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• pp.749-760
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• 2022

An efficient computational fluid dynamics model was proposed for simulating microchannel-type steam/methane reformers with thin washcoat catalyst layers. In this model, by using the effectiveness factor correlations, the overall reaction rate that occurs in the washcoat catalyst layer could be accurately estimated without performing the detailed calculation of heat transfer, mass transfer, and reforming reactions therein. The accuracy of the proposed model was validated by solving a microchannel-type reformer, once by fully considering the complex steam/methane reforming (SMR) process inside the washcoat layer and again by simplifying the SMR calculation using the effectiveness factor correlations. Finally, parametric studies were conducted to investigate the effects of operating conditions on the SMR performance.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.6
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• pp.602-608
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• 2014

Hydrogen energy, a field of low-carbon substitute energy, can be produced by fossile fuel reforming and electrolysis of water etc. We developed 1kW class flat type reformer for PEM Fuel Cells. The PEMFC is highly sensitive to carbon monoxide because CO has detrimental effects on the performance of the fuel cell. Thus, reformed gas supplied to Fuel cell system, which maintained CO concentration below 10ppm. After applying optimum drive condition, reformed gas was measured with gas chromatography and could find out about each experimental condition of $H_2$ and CO concentration. As a results, The 1kW class plate type hydrogen generation system's optimum condition is A/F ratio ${\alpha}=1.3$, STR temperature 1023K, S/C ratio 3, and $PrOx1{\cdot}2$ 30cc/min. It turns out that installation of PrOx 2 stage is more efficient for reducing CO concentration.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.1997-2002
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• 2007

The reformer is one of the most important chemical processes for the production of high purity hydrogen from fossil fuel. This study compares zero-dimensional model with CFD models for reaction analysis of methane-steam reformer. The zero-dimensional model is an empirical equation, however CFD model uses reactions of Arrhenius type. Because the reaction coefficients of the steam-methane catalytic reforming have not been reported before in the form of Arrhenius type, the present study aims to find the appropriate reaction coefficients. The used CFD code is Fluent 6.2 version. Several models are compared for the case of various operating temperature, mass of catalyst and steam to methane ratio.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.41-44
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• 2007

Steam reforming reaction of natural gas is an important process for fuelcell commercialization. In this paper, steam reforming reaction is studied by numerical method. Pseudo-homogeneous model is incorporated for chemical reactions and one medium approach is used to take into account thermally equilibrium phenomena between catalyst and bulk gas. The model is validated with our experimental results under the same operating conditions. Because performance of reformer has relation to heat flux from wall, heat flux profiles was investigated by using Nusselt number. Value of Nusselt number in steam reformer is larger than one in channel, which does not have chemical reaction because steam reforming reaction is an endothermic reaction. When the difference of Nusselt number at the front and the rear is larger, performance is improved.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.172-175
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• 2006

Steam reforming of methane using Xe-arc solar simulator was studied for converting solar radiation into energy foam that one can readily utilize. The Xe-arc lamp produce a spectrum similar to that of the sun. SiC ceramic foam, resist high temp.$(>900^{\circ}C)$, is used to catalytically active foam absorber, and to support of reforming catalyst. The catalyst on the surface of foam were directly irradiated with solar simulated xe-light in order to carry out the steam reforming of methane. The reactor was made of stainless steel and quartz window was located on a place of the xe-light irradiation and temperature was controlled using K-type thermocouple in contact with catalyst located inside the reactor. The result show that a possibility of solar reforming using catalytically active foam absorber is exist.

• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.25-28
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• 2008

Steam reforming reaction is a matured technology to get hydrogen from hydrocarbon fuels compared with other reforming reactions such as partial oxidation(POX), autothermal reforming(ATR). It is so endothermic that it needs heat source to activate the reaction. Due to the reaction characteristics, heat transfer limitation phenomena generally occur in the steam reformer. As one of new ideas, the effect of discontinuous gas feeding is investigated based on heat transfer characteristics. The new operating method is usually favorable at high GHSV region(i.e. over $10,000h^{-1}$). In order to numerically simulate the physical issues, numerical approach is adopted based on heterogeneous reaction model, two-equation model in energy equation, and other constitutive models in porous media.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.256-259
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• 2005

본 연구에서는 기존 니켈 활성성분만의 알루미나담지 촉매에 비해 고온에서의 수소를 사용한 환원 전처리 과정을 거치지 않고도 높은 반응활성을 나타내며, 반응 중 탄소침적에 대한 촉매 저항성에서도 우수한 결과를 나타낸 루테늄-니켈 촉매에 대해보고 하고자 한다. 메탄 수증기 개질 반응을 통해, 루테늄을 최종적으로 담지한 알루미나 담지니켈계 촉매는 별도의 전처리과정 없이 $650^{\circ}C$에서부터 높은 반응성을 보였으며, 루테늄과 니켈을 동시에 담지한 경우보다 더 우수한 활성을 나타내었다. Ru의 담지량을 달리한 실험에서는$RU(0.5)/Ni(20)/Al_2O_3$ 촉매가 가장 높은 활성을 보였다. $H_2-TPR$ 분석 결과, $Ru(0.5)/Ni(20)/A1_2O_3$촉매의 경우 세 가지 환원 피크가 나타났으며, $Ni(20)/A1_2O_3$촉매와 비교해 볼 때, 저온(<$130^{\circ}C)$에서 환원가능한 $RUO_2$의 존재를 확인할 수 있었다. 담지된 RU은 분산도가 높아, XRD분석 결과에서 Ru이나 $RuO_2$의 특성 피크가 존재하지 않았다. 또한 $650^{\circ}C$에서 10시간 개질반응 후 얻어진 촉매에 대해 $O_2-TGA$를 분석한 결과, $Ni(20)/Al_2O_3$촉매는 $-7.2wt\%$ 정도의 큰 무게 감소를 보였으며, 이는 촉매 표면에 생성된 carbon tube에 의한 것임을 SEM 분석을 통해 알 수 있었다 이에 반해, $Ru(0.5)/Ni(20)/Al_2O_$ 촉매는 $O_2-TGA$시 $0.3wt\%$ 정도 무게 증가에 그쳤으며, SEM 분석상 carbon tube의 생성이 크게 억제되었음을 알 수 있었다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.3
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• pp.343-350
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• 2012

A planar solid oxide fuel cell (PSOFC) is studied in its application in a high-temperature stationary power plant. Even though PSOFCs with external reformers are designed for application from the distributed power source to the central power plant, such PSOFCs may sacrifice more system efficiency than internally reformed SOFCs. In this study, modeling of the PSOFC with an external reformer was developed to analyze the feasibility of thermal energy utilization for the external reformer. The PSOFC system model includes the stack, reformer, burner, heat exchanger, blower, pump, PID controller, 3-way valve, reactor, mixer, and steam separator. The model was developed under the Matlab/Simulink environment with Thermolib$^{(R)}$ modules. The model was used to study the system performance according to its configuration. Three configurations of the SOFC system were selected for the comparison of the system performance. The system configuration considered the cathode recirculation, thermal sources for the external reformer, heat-up of operating gases, and condensate anode off-gas for the enhancement of the fuel concentration. The simulation results show that the magnitude of the electric efficiency of the PSOFC system for Case 2 is 12.13% higher than that for Case 1 (reference case), and the thermal efficiency of the PSOFC system for Case 3 is 76.12%, which is the highest of all the cases investigated.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.1
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• pp.100-108
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• 2011

The use of biogas as an energy source reduces the chance of possible emission of two greenhouse gases, $CH_4$ and $CO_2$, into the atmosphere at the same time. Its nature of being a reproducible energy source makes its use even more attractive. This research if for the hydrogen production through the steam reforming of the biogas. The biogas utilized 3D-IR matrix burner in which the surface combustion is applied. The nickel catalyst was used inside a reformer. Parametric screening studies were achieved as Steam/Carbon ratio, biogas component ratio, Space velocity and Reformer temperature. When the condition of Steam/Carbon ratio, $CH_4/CO_2$ ratio, Space velocity and Refomer temperature were 3.25, 60%:40%, 19.32L/$g{\cdot}hr$ and $700^{\circ}C$ respectively, the hydrogen concentration and methane conversion rate were showed maximum values. Under the condition mentioned above, $H_2$ concentration was 73.9% and methane conversion rate was 98.9%.

• Transactions of the Korean hydrogen and new energy society
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• v.28 no.6
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• pp.618-626
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• 2017

Conventional high temperature reformers are not suitable for hybrid fuel cell systems that use waste heat as a heat source. So, development of a low temperature type reformer is needed. However, the analysis was conducted in two ways to increase the thermal efficiency, because of low reforming rate due to the low heat source. First, it is a way to ger thermal gain from the outside through partial insulation. In the case of one heat source tube and several heat source tubes, we analyzed the effect of partial heat insulation in some cases. Second, we found the most efficient arrangement of the heat source tubes by changing the location of the heat source tubes. The interpretation was carred out using the COMSOL Mutiphysics program.