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RISS 인기검색어
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- 저자 : 강경문(Kyungmun Kang) (검색결과 4 건)
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강경문(Kyungmun Kang),이주한(Juhan Lee),조현석(Hyunsuk Cho),서태범(Taebeom Seo) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
The objective of this paper is to describe the experimental and numerical investigation of the analysis of the heat transfer in a solar chemical reactor. These are compared about methane steam reforming process in the solar chemical reactor which was a volumetric absorber consisting of honeycomb and a multilayered catalyst supports. With this high operating temperature, convective heat loss, thermal fracture are important features for designing SCR. In order to estimate the system performance and to design the actual solar reactor with various conditions, CFD analysis was used in this study. The nickel oxide porous metal is inserted inside the solar chemical reactor to increase the conversion rate of the reforming reaction. Simulation has been carried out based on the experimental data. According to the simulation results, the optimum methane-steam mole ratio and thickness and numbers of catalyst supports were obtained.
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고분자전행질형 연료전지내 마이크로다공층 영향에 대한 수치적 연구
강경문(Kyungmun Kang),주현철(Hyunchul Ju) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
In the fuel cell community it is well-known that a micro-porous layer (MPL) plays a crucial role in the water management of polymer electrolyte fuel cells (PEFCs), and thereby, significantly stabilizes and improves cell performance. In this paper, a numerical MPL model is developed and embodied with comprehensive, multi-dimensional, multi-phase fuel cell models that were developed earlier to discover the exact roles of MPLs,. The effects of different porous properties and liquid-entry pressures between an MPL and a gas diffusion layer (GDL) are examined via fully three-dimensional numerical simulations. Discontinuity in liquid saturation at the GDL/MPL interface is captured by the model when the differences in pore properties and wettability between the MPL and GDL are taken into account without considering variation in the liquid-entry pressures. However, the simulation of this case fails to capture the beneficial effects of an MPL on cell performance, predicting even lower performance than the case of no MPL. On the other hand, when a high liquid-entry pressure in an MPL is additionally considered, the numerical MPL model predicts liquid-free MPL and successfully demonstrates the phenomenon that the high liquid-entry pressure of the MPL prevents any liquid water from entering the MPL. Consequently, it is found from the simulation results that the liquid-free MPL significantly enhances the back-flow of water across the membrane into the anode, which, in turn, helps to avoid membrane dehydration and alleviate the level of GDL flooding. As a result, the model successfully reports the beneficial effects of MPLs on PEFC performance and predicts higher performance in the presence of MPLs (e.g., an increase of 67 ㎷ at 1.5 A ㎝-2). This study provides a fundamental explanation for MPL functions and quantifies the influence of MPL’s porous properties and the liquid-entry pressure on water transport and cell performance.
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강경문(Kang, Kyungmun),고요한(Ko, Johan),이기용(Lee, Giyong),주현철(Ju, Hyunchul) 한국신재생에너지학회 2010 한국신재생에너지학회 학술대회논문집 Vol.2010 No.06
In this paper, both theoretical and experimental investigations have been performed to examine the effects of key operating parameters on the cell performance of a DMFCs (i.e., methanol feed concentration and operating temperature). For experiment, the membrane electrode assemblies (MEAs) were prepared using a conventional MEA fabrication method based on a catalyst coated electrode (CCE) and tested under various cell temperatures and methanol feed concentrations. The polarization curve measurements were conducted using in-house-made 25cm² MEAs. The voltage-current density data were collected under three different cell temperatures (50?C, 60?C, and 70?C) and four different methanol feed concentrations (1 M, 2 M, 3 M, and 4 M). The experimental data indicate that the measured I-V curves are significantly altered, depending on these conditions. On the other hand, previously developed one-dimensional, two-phase DMFC model is simulated under the same operating conditions used in the experiments. The model predictions compare well with the experimental data over a wide range of these operating conditions, which demonstrates the validity and accuracy of the present DMFC model. Furthermore, both simulation and experimental results exhibit the strong influences of methanol and water crossover rates through the membrane on DMFC performance and I-V curve characteristics.
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