• 전기화학회지
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• 제5권1호
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• pp.27-29
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• 2002

본 연구는 메탄올과 공기를 이용하여 상온, 상압에서 전기를 발생시키는 휴대폰용 전원공급 장치의 개발에 관한 것이다. 이 장치는 직접 메탄을 연료전지(DMFC)와 Back-up전지가 병렬로 연결되어 있어, 통화시 소요 전력의 최대 $50\%$ DMFC가 공급하고 나머지 부분은 Back-up 전지가 공급한다. 또한 통화 대기시에는 DMFC가 $100\%$ 필요 전력을 공급하고, 잉여 전력으로 Back-up전지를 충전한다. 상기 DMFC는 유효면적이 $9cm^2$인 8개의 단위전지가 직렬로 연결되어 있으며, 휴대폰의 작동 전압 범위인 2.5-3.9V의 전압을 출력한다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.27-30
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• 2007

This study considers the feasibility of the concentration control of the methanol solution by oscillating flow in the anode channel of passive type Direct Methanol Fuel Cells(DMFC). DMFC stack performance is largely influenced by the fuel concentration. If the fuel concentration is either lower than 0.5M or more than 2M, its performance deteriorates seriously because of the fuel starvation or the fuel crossover. In this respect the optimization of the fuel concentration is crucially important to maximize the DMFC stack performance. In this work, the effects of oscillating actuation in the fuel supply are studied to control the fuel concentration. Two important nondimensional parameters are introduced, each of which represents either the oscillating frequency or the oscillating amplitude. It is shown how these factors affect the stack performance and the efficiency of the DMFC stack.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.45-48
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• 2008

This paper presents a passive air-breathing direct methanol fuel cell (DMFC) which has been designed and tested. The single cell is fuelled by methanol vapor that is supplied through flow channel from a methanol reservoir at the anode, and the oxygen is supplied via natural air-breathing at the cathode. The methods for supplying the methanol vapor to the single cell were parallel channel and chamber. This research investigates various methods to identify the effects of using flow channels for providing the methanol vapor at the anode, and the opening ratio between the inlet and outlet ports for the methanol flow at the anode. The best flow channel condition for passive DMFC was a chamber, and the opening ratio was 0.8. Under these conditions, the peak power was 10.2mW/$cm^2$ at room temperature and ambient pressure. The key issues for the Passive DMFCs for using methanol vapor are that sufficient methanol needs to be supplied using a large as possible opening ratio. However, it is shown that the performance of the passive DMFC, which has a channel at the anode,is low due to the low differential pressure and insufficient methanol supply rate.

• 한국수소및신에너지학회논문집
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• 제22권3호
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• pp.292-298
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• 2011

This study examines the effects of the ambient temperature (AT), methanol feeding temperature (MFT), methanol concentration (MC) and methanol flow rate (MFR) on the performance and cell temperature (CT) of a 5-stacked direct methanol fuel cell (DMFC). The AT, MFT, MC, and MFR are varied from $-10^{\circ}C$ to $+40^{\circ}C$, $50^{\circ}C$ to $90^{\circ}C$, 0.5M to 3.0M and 11.7 mL $min^{-1}$ to 46.8 mL $min^{-1}$, respectively. The performance of the DMFC under various operating conditions is analyzed from the I-V polarization curve, and the methanol crossover is estimated by gas chromatography (GC). The performance of the DMFC improves significantly with increasing AT. The open circuit voltage (OCV) decreases with increasing MC due to the enhanced likelihood of methanol crossover. The cell performance is improved significantly when the MFR is increased from 11.7 mL $min^{-1}$ to 28.08 mL $min^{-1}$. The change in cell performance is marginal with further increases in MFR. The CT increases significantly with increasing AT. The effect of the MFT and MFR is moderate, and the effect of MC is marginal on the CT of the DMFC.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제53권4호
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• pp.218-224
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• 2004

We present a miniature Direct Methanol Fuel Cell (micro-DMFC) using platinum sputtered microcolumn electrodes with a limited amount of fuel. We use the microcolumn electrode in order to improve the power density of the micro-DMFC that consists of two electrodes and polymer electrolyte. We also design the built-in fuel chamber in the anode for the portable electronics applications. We design and fabricate both microcolumn and planar electrodes, having an identical projective area of 5mm${\times}$5mm. The diffusion current density of the microcolumn electrode is 1.73 times higher than that of the planar electrode at electrode potential of 1.1V in the half-cell test. The micro-DMFC based on the microcolumn electrodes shows the maximum power of 10.8$\pm$7.54㎼(43.23$\pm$0.16㎼/$\textrm{cm}^2$) at the projective area of 5mm${\times}$5mm, while the planar electrode micro-DMFC shows the maximum power of 0.81$\pm$0.42㎼(3.24$\pm$1.68㎼/$\textrm{cm}^2$) at the same projective area. The micro-DMFC based on the microcolumn electrodes shows 13 times higher power density that the micro-DMFC based on the planar electrodes does.

• 한국전기화학회:학술대회논문집
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• 한국전기화학회 2003년도 추계총회 및 학술발표회
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• pp.13-13
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• 2003

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.126.1-126.1
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• 2010

In direct methanol fuel cells(DMFCs), it is well known that methanol crossover severely reduces the cell performance and the cell efficiency. There are a number of design and operating parameters that influence the methanol crossover. This indicates that a DMFC demands a high degree of optimization. For the successful design and operation of a DMFC system, a better understanding of methanol crossover phenomena is essential. The main objective of this study is to examine methanol-crossover phenomena in DMFCs. In this study, 1D DMFC model previously developed by Ko et al. is used. The simulation results were compared with methanol-crossover data that were measured by Eccarius et al. The numerical predictions agree well with the methanol crossover data and the model successfully captures key experimental trends.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1409-1411
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• 1996

Direct Methanol Fuel Cell(DMFC) using Pt-Ru electrocatlayst and Nafion menbrane can provide high performance if operating conditions are well designed. In this study, operating temperature, pressure, and fuel flow rate were changed to obtain optimum operating conditions of DHFC single cell. Performance of DMFC were increased by the increase of operating temperature. The concentration of fuel methanol was 2.0M $CH_{3}OH$ and pressure difference of cathode and anode was 2 atm were showed maximum performance of DMFC single cell with showing the current density of 160 $mA/cm^2$ at 0.2V cell voltage.

• 신재생에너지
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• 제3권1호
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• pp.46-53
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• 2007

Direct Methanol Fuel Cell, DMFC is a potential power source for portable IT application. DMFC works at low temperature ($<100^{\circ}C$) without fuel processing. Methanol has high energy density, fuel economy, and easiness to handle. This paper focuses high efficient catalyst to increase utilization in the electrode, new membrane reducing methanol crossover, new material parts, and optimization of system integration. Lightweight and small-sized DMFC based on new materials, efficient stack, and improved system control will be applied to the 50W prototype system for the notebook computer.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 추계학술대회
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• pp.490-493
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• 2006

The results of simulation of direct methane fuel cell fed with liquid-state methanol feed are shown. This numerical process is based on mass and current conservation equations. The results showed that over low current density $(<200mA/cm^2)$ IV polarization curve was well-presented compared to experimental result. Methanol fed from anodic side moved into cathodic side through electrolyte membrane and the pressure near cathode electrode increased according to amount of methanol crossover and production of water. Besides change of overpotential on each el electrode were checked by x-axis.