• Journal of the Korean Electrochemical Society
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• v.13 no.3
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• pp.193-197
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• 2010

In terms of the system efficiency, it is very useful to apply the ejector into the fuel recirculation system of a fuel cell system since the ejector needs no parasitic power to operate. Since the conventional automotive fuel cell use hydrogen and air as their fuel, the only hydrogen is needed to be recirculated for the better fuel efficiency. On the other hand, the submarine fuel cell needs both hydrogen and oxygen recirculation systems because the submarine drives under the sea. In particular, the cathodic recirculation has to meet the tougher target since the oxygen based pressurized stack generally used in the submarine applications generates the significant amount of the water in the stack during the operation. Namely, the oxygen utilization has designed less than 50% in the whole operating range for the better exhausting of the generated waters. And thereby in terms of the oxygen utilization, the entrainment ratio of the ejector should be more than 1 within the whole operating range. However, the conventional ejector using a constant nozzle can not afford to satisfy the mentioned critical requirement. To overcome the problem, the dual-ejector and its control strategy are designed. The performance of the proposed dual-ejector is verified by the experiments based on the real operating conditions of the target submarine system. Furthermore, the proposed design method can be used for the other fuel recirculation system of a large-scale fuel cell system with the critical requirement of the fuel utilization.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.342-350
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• 2009

Fuel cells convert a fuel together with oxygen in a highly efficient electrochemical reaction to electricity and water. Since the electrochemical reaction in the fuel cell stack dose not generate any noise, Fuel cell systems are expected to operated much quieter than combustion engines. However, the tonal noise and the broad band noise caused by a centrifugal compressor and an electric motor cause which is required to feed the ambient air to the cathode of the fuel cell stack with high pressure. In this study, the multi-camber perforated muffler is used to reduce noise. We propose optimized muffler model using an axiomatic design method that optimizes the parameters of perforated muffler while keeping the volume of muffler minimized.

• Proceedings of the KIEE Conference
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• 1997.07a
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• pp.100-103
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• 1997

Korea Electric Power Corporation (KEPCO) started a fuel cell project to develop alternative sources of electric power because of the rapid increase in power demand and global environmental problems. For the development of a molten carbonate fuel cell (MCFC), KEPCO started the project in 1993 to develop a 2 kW MCFC system and finished it at the end of 1996. In this project, $ASPEN^+$ was utilized to design the 2 kW MCFC generation system. Based on this simulation, a power generation system was designed and installed for operation and a long term test of internally manifolded 2 kW class MCFC stack. This stack has 20 cells with an effective electrode area of $1000\;cm^2$. It was run at 0.84 V and $150\;mA/cm^2$ and was operated for more than 3,250 hours continuously. This paper describes the system configuration and its control and measurement units. An analysis of the stack performance, the effect of gas utilization ratio, and the stack performance requirements are also discussed.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.123.1-123.1
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• 2010

The solid oxide fuel cell (SOFC) has attracted great deal of attention due to its high electrical efficiency, high waste-heat utilization, fuel flexibility, and application versatility. However, SOFC technology is still not matured enough to fulfill the practical requirements for commercialization. Therefore, all the research and development activities are mainly focused on a development of practically viable SOFCs with higher performance and better reliability. We were successful in fabricating high-performance anode-supported unit cells by employing hierarchically controlled multi-layered electrodes for both structural reliability and high performance. In addition, a novel composite sealing gasket made it possible to achieve excellent sealing integrity even with considerable surface irregularities in a multi-cell planar arrayed stack.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2144-2148
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• 2008

Kerosene-driven solid oxide fuel cell (SOFC) system with reformer, desulfurizer and after-burner was mainly developed for this study. Originally the system was developed for 1kW class SOFC system for residential power generation (RPG) application. As a preliminary study of 1kW class SOFC system operation, a short stack was applied to the system. The short stack consists of 7 cells of $10cm{\times}10cm$ area and was operated at $720^{\circ}C$. The effect of anode inlet gas composition to stack performance was investigated. Firstly, I-V characteristics of SOFC with different fuel of kerosene and hydrogen were studied. Secondly $CH_4$ internal reforming was performed at various anode inlet gas compositions of $H_2$, $CH_4$ and $H_2O$. Through these experiments the effects of each anode inlet gas component to stack performance were analyzed and the significant operating parameters were iscussed.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.100.1-100.1
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• 2011

Electrochemical impedance spectroscopy(EIS) are using widely as a useful technique mainly in the field of electrochemical for the analysis of electrode reactions or characteristics of the composites. The response analysis of the systems technique provides comprehensive informations about the characteristic and structure of complex and internal reaction. The EIS is the method to measure impedance of the measurement target classified by the frequency, it select the equivalent impedance model to give same response from the result and it calculate the parameter. Therefore, the chemical reaction inside the fuel cell is to modeling to electrical impedance. And as repeating the same experiment in each of the operating point, we can get each different parameter. As a result, we can establish the equivalent impedance model in each operating point. Therefore, if we use these models, we can evaluate the fuel cell without the internal design parameter of the fuel cell as required in existing modeling. The EIS is used typically technique for distinguish status of fuel cell called SOH(State Of Health). When the fuel cell is degradation, Efficiency and health of the fuel cell is reduced because internal impedance is increase. As usage of these principles, we can evaluate state of fuel cell through the impedance analysis of fuel cells. In this study, we are presents EIS distinction system and algorithm for residential fuel cell systems. At the time of the fuel cell installation in the fields, the EIS system and proposed algorithm will be able to apply as technique for efficiency and performance evaluation about fuel cell system.

• Journal of the Korean Electrochemical Society
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• v.6 no.1
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• pp.23-27
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• 2003

In this study investigations have been carried out for the evaluation of small DMFCS under passive operation conditions for use in portable powers. Under passive conditions, a maximum performance was obtained at a methanol concentration of 4 M and at a catalyst loading of $8mg/cm^2$ on both electrodes. By optimizing various parameters, we could achieve the highest performance of $55mW/cm^2$ at 1 attn and at R.T.A monopolar stack consisting of 6 unit cells with active area of $4.5cm^2/cell$ was prepared and it showed a uniform voltage distribution all over the cells and it had a power output of 1 watt and a power density of $37mW/cm^2$ A monopolar stack which consisted of 16 cells and produced a 2.4W power was also fabricated and was tested for operation of a miniature car.

• Transactions of the Korean hydrogen and new energy society
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• v.23 no.4
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• pp.323-329
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• 2012

A thermal management system of a proton exchange membrane fuel cell is taken charge of controlling the temperature of fuel cell stack by rejection of electrochemically reacted heat. Two major components of thermal management system are heat exchanger and pump which determines required amount of heat. Since the performance and durability of PEMFC system is sensitive to the operating temperature and temperature distribution inside the stack, it is necessary to control the thermal management system properly under guidance of operating strategy. The control study of the thermal management system is able to be boosted up with hardware in the loop simulation which directly connects the plant simulation with real hardware components. In this study, the plant simulation of fuel cell stack has been developed and the simulation model is connected with virtual data acquisition system. And HIL simulator has been developed to control the coolant supply system for the study of PEMFC thermal management system. The virtual data acquisition system and the HIL simulator are developed under LabVIEWTM Platform and the Simulation interface toolkit integrates the fuel cell plant simulator with the virtual DAQ display and HIL simulator.

• Transactions of the Korean hydrogen and new energy society
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• v.15 no.4
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• pp.291-300
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• 2004

Performance of PEMFC is affected by many factors such as that of MEA, configuration of flow field, operating conditions, humidification, cooling and so on. In this study, in order to improve the performance of fuel cell, a small area fuel cell stack was made and its performance was tested under various operating conditions. Stack consists of 3 single PEM fuel cells. Channel is serpentine type and the active area of the electrode is $50cm^2$. The test results show that the peak power is 60W at $70^\circ{C}$ of stack temperature with humidification condition.

• New & Renewable Energy
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• v.1 no.4 s.4
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• pp.25-29
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• 2005

연료전지 차량이 기존의 내연기관 차량과 동등한 성능을 확보하기 위해서는 80kW 이상의 용량을 가진 스택이 탑재되어야 하며, 별도로 차량 구조를 변경시키지 않고 탑재하기 위해서는 높은 출력밀도를 가진 연료전지 스택의 개발이 필요하다. 현대 자동차가 독자 기술로 개발하고 있는 연료전지 스택은 출력 80kW, 출력밀도 1.0kW/l를 목표로 하고 있으며 지난 1년간의 과제 수행을 통해 어느 정도 성능을 만족하는 스택을 개발하였다. 앞으로는 연료전지 스택의 내구성 및 냉시동성을 개선하기 위해 많은 연구가 수행될 예정이다.