• New & Renewable Energy
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• v.3 no.1 s.9
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• pp.75-82
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• 2007

Aluminum was used as metallic bipolar plate material to reduce a stack weight. The functional materials such as conductive material, Au and nonconductive material, PTFE [polytetrafluoroethylene] were coated on the bipolar plate to enhance electrical contact and corrosion prevention in PEMFC. The active area of bipolar plate is divided into the top layer part that electric current mainly passes, and the bottom layer part that gas and water pass. The bottom layer part in the flow channel needs not to have electrical conductivity because it doesn't pass electric current directly. In this reason, Au on the top layer and PTFE on the bottom layer were coated to apply high electrical conductivity and/or good corrosion resistance. Although the single cell performance using Au-PTFE/Al bipolar plate was shown 78% in comparison with that of graphite, specific power of Au-PTFE/Al bipolar plate(0.4 W/g) was twice as much as graphite bipolar plate.

• Journal of the Korean Ceramic Society
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• v.40 no.2
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• pp.159-166
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• 2003

The preparation method for composite membranes of high temperature operation above $100^{\circ}C$ for Polymer Electrolyte Membrane Fuel Cells (PEMFCs ) was presented, using perfluorosulfonylfluoride Nafion resin and mordenite, in addition to the physical properties, proton conductivity and single cells performance for it. The composite membranes were fabricated via melting of Nafion resin with various mordenite content. As the increase of mordenite content, at high temperature range, proton conductivity of the composite membrane increased due to the late dehydration rate of existent water in the mordenite. Also, from the result of the current-voltage relationship for single cells under $130^{\circ}C$ operation condition, the composite membrane cell with l0 wt% mordenite content showed better performance than that of the others over the entire current density range. This result indicated that the existent water in the composite membrane with l0 wt% mordenite content was higher than that with the others, thereby maintains its conductivity. Based upon the results of experiments, therefore, a Nafion/mordenite composite membrane prepared by this work is thought to be a satisfactory polymer electrolyte membrane for PEMFC operation above $100^{\circ}C$.

• 한국전기화학회:학술대회논문집
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• 2003.07a
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• pp.173-176
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• 2003

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.239-242
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• 2005

고분자 전해질형 연료전지에서는 수소이온의 이온전도성 저하를 방지하기 위하여 외부에서 가습하여 주는 방식이 일반적이지만, 가습에 소요되는 부품을 일부라도 제거할 경우 연료전지의 효율은 높이고 제작단가도 경감할 수 있다. 이를 위하여 저가습 및 무가습 실험을 수행하였으며, 정확한 data의 수집과 시험장비의 자동제어를 위하여 National Instrument사의 compact field point (cFP)를 사용하였다. 무가습 실험 중 stack의 안정성 측면을 고려하기 위하여 수소연료가 부족하거나 갑작스런 voltage drop이 발생할 경우 LabVIEW logic에 의한 stack 보호용 자동차단 시스템을 구현하였다. Humidifier와 heater의 온도를 조절하여 공급유체의 상대습도 및 온도를 각각 조절하였으며, 이에 필요한 이론적 온도는 Antoine equation을 사용하여 산정하였다. Anode와 cathode 양측 $100\%$ 가습 경우를 기준으로 가습량을 조절하면서 실험을 수행하였으며 성능 차이를 그래프로 도시하여 양측의 변화에 대한 영향을 볼 수 있도록 하였다. Stack의 온도가 $70^{\circ}C$이고 양측 무가습일 경우에 성능 측정이 불가능하여 stack의 온도를 저온에서부터 변화시키면서 무가습 성능을 실시간으로 측정하여 보았다 일반적으로 hydronium ion은 anode측에서 cathode측으로 계속 이동하여야 전기를 생성할 수 있으므로 cathode측 무가습이 anode측 무가습보다 성능이 더 잘 나오는 것으로 예측하였으나 이와 반대되는 경향의 실험 결과를 얻었다. Anode측 무가습과 cathode측 무가습의 standard deviation은 anode 무가습일 경우가 크게 발생하였고 양측 무가습일 경우는 stack의 온도가 높을수록 크게 관찰되었다. 이와 같은 현상은 공기중의 상대습도와 back diffusion등에 영향을 받을 수 있으므로 각종 변수들의 영향을 분리하여 관찰할 수 있는 실험을 수행중에 있다.

• Transactions of the Korean hydrogen and new energy society
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• v.18 no.4
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• pp.422-431
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• 2007

Polymer electrolyte membrane fuel cell(PEMFC) is very interesting power source due to high power density, simple construction and operation at low temperature. But it has problems such as high cost, improvement of performance and effect of temperature. These problems can be approached to be solved by using mathematical models which are useful tools for analysis and optimization of fuel cell performance and for heat and water management. In this paper, the present work is to develop an electrochemical model to examine the electrochemical process inside PEM fuel cell. A complete set of considerations of mass, momentum, species and charge is developed and solved numerically with proper account of electrochemical kinetics. When depth of gas channel becomes thinner, diffusion of reactant makes well into gas diffusion layer(GDL) and the performance increases. Although at low current region there is little voltage difference between experimental data of PEM fuel cell and numerical data. When the porosity size of gas diffusion layer for PEM fuel cell is bigger, oxygen diffusion occurs well and oxygen mass fraction appears high in catalyst layer.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.6
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• pp.593-601
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• 2011

An analysis program to simulate the operation of a polymer electrolyte membrane fuel cell (PEMFC) system was set up, and system operation with variations in the working conditions of various components (especially the thermal management system) was simulated. The entire system included a PEMFC stack and balance-of-plant components such as an air-supply unit, a fuel-supply unit, and a heat-management unit (cooling system). Thermodynamic models of all components were made to evaluate the design performance of the entire system, and then off-design models were set up to simulate the operation of the entire system under arbitrary working conditions. A parametric study was carried out to examine the effects of varying the operating conditions (especially the ambient conditions and the operating conditions of the cooling system) on the operation and performance of the entire system.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.683-684
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• 2011

연료전지시스템을 항공기 동력원으로 사용하기 위해서는 요구되는 출력에 필요한 스택성능과 한정된 부피 내 연료전지시스템을 탑재하기 위한 운전장치 구성, 그리고 무게를 최소화하기 위한 부품 및 재료 선정이 필요하다. 스택의 기본성능은 MEA(Membrane electrode assembly)와 기체확산층 구조, 분리판 디자인 및 운전조건 등에 의해 결정된다. 스택의 기본성능은 연료전지시스템을 구성하는 운전장치 구성 및 성능에 의해 달라지기 때문에 어떠한 운전장치를 어떠한 구성으로 설계하는가에 따라서 성능이 변한다고 볼 수 있다. 본 연구에서는 연료전지시스템을 항공기 동력원으로 사용하기 위해서 고려되어야할 스택과 운전장치의 구성이 성능에 미치는 영향과 운전환경(스택 경사, 고도)이 연료전지 스택성능에 미치는 영향에 대해 고찰하였다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.3
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• pp.207-214
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• 2009

Crossover of nitrogen from cathode to anode is inevitable in typical membranes used in PEM fuel cells. This crossovered nitrogen normally accumulates in the hydrogen recirculation system at anode side channels. Excessive buildup of nitrogen in the anode side lowers the relative hydrogen concentration and finally affects the performance of fuel cell stack. So it is very important to analysis the nitrogen gas crossover at various operating conditions. In this study, characterization of nitrogen gas crossover in PEM fuel cell stack was investigated. The mass spectroscopy (MS) has been applied to measure the amount of the crossovered nitrogen gas at the anode exit. Results show that nitrogen gas crossover rate was affected by current density, anode and cathode stoichiometric ratio and operating pressure. Current density, anode stoichiometric ratio and anode operating pressure do not affect nitrogen crossover rate but anode exit concentration of nitrogen. Cathode pressure and stoichiometric ratio largely affect the nitrogen crossover rate.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.553-556
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• 2007

Hyundai${\cdot}$Kia Motors have developed PEMFC stack technologies for passenger car application in 1998. The developed 80kW class stack, which was installed Kia's Sportage FCV in 2005, has been modified for -10$^{\circ}C$ cold start-up and ensuring the stability and durability by using new technologies such as newly designed separator, manifold block, end plate, and so on. And also, the stack durability has been verified over 1,500hrs with the condition of combined vehicle driving mode. Hyundai${\cdot}$Kia Motors will keep continuing the stack R&D to reach the goal of FCV commercialization.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.109-112
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• 2007

In this paper, a mathematical modeling was developed to simulate 1kW class air cooled Polymer Electrolyte Membrane Fuel Cell(PEMFC) system. The proposed modeling was conducted under SIMULINK based environment. The model ing was developed based on the thermodynamic and chemical equilibrium. The objective is to design and implement the entire fuel cell system model ing including the system controller modeling. The fuel cell process and the control system modeling should have to be connected with each other simultaneously， therefore the two types of modeling influences each other when the system simulator run. The fuel cell modeling libraries are simulated using the SIMULINK under the thermodynamic and chemical equilibrium base. The PID controller application was designed and developed to test the process modeling and verify it. This the prototype development of the fuel cell system to design and test more complicate fuel cell systems, like the residential power generation system. The simulation results was compared to the real PEMFC system performance. We have achieved the reasonable accordance with the Lab test and the simulation results.