• 한국수소및신에너지학회논문집
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• 제19권2호
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• pp.118-123
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• 2008

For the hydrogen recirculation system of the PEMFC (polymer electrolyte membrane fuel cell), the ejector is useful to improve the efficiency of the fuel cell system. However, conventional ejector does not keep its entrainment ratio good when the various power duties is required by the fuel cell system. In this study, the variable multi-ejector acceptable in the whole duty range required from the fuel cell hybrid mini-bus is developed. Consequently, the performance of the developed ejector is verified by the experiments based on the real operating conditions.

• 한국수소및신에너지학회논문집
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• 제24권6호
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• pp.467-471
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• 2013

In present work, optimized the manufacturing process of anode-supported tubular SOFCs cell and stack were studied. For this purpose, we first developed a high performance tubular SOFC cell, and then made electrical connection in series to get high voltage. The gas sealing was established by attaching single cells to alumina jig with ceramic bond. Through these process, we can obtain such high OVP as around 15V, which means that the electrical connection and gas sealing were optimized. Finally we developed a new tubular SOFC stack which shows a maximum power of 65W @ $800^{\circ}C$.

• 한국수소및신에너지학회논문집
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• 제17권2호
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• pp.133-140
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• 2006

The performance of proton exchange membrane fuel cell was decreased by reverse voltage using fuel starvation. Performance decrease in local area could be affected by duration and extent of reverse voltage. Hydrogen and air stoichiometic ratio was used to find the experimental condition of abrupt voltage decrease. LabVIEW was used to make control logic of automatic load off system in preset voltage. Reverse voltage experiment was done down to -1.2 V at constant current condition. When fuel cell voltage was reached to preset voltage, electronic load was disconnected to make open circuit voltage for 1 minute. Fuel cell performance was checked every 5 cycle and the degree of performance decrease and/or recovery was estimated. Ohmic resistance and charge transfer resistance were increased and platinum surface area was reduced 41% after reverse voltage experiment.

• 한국수소및신에너지학회논문집
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• 제22권2호
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• pp.129-138
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• 2011

Performance changes of an anode-supported tubular SOFC including current collectors are analyzed at different current collecting methods using numerical simulation. From the two dimensional numerical model of the solid oxide fuel cell with nickel felts as anodic current collectors and silver wires as cathodic ones, the performance curves and the distributions of temperature, concentration, current density are obtained. Also, the voltage loss of the cell is divided into three parts: activation loss, concentration loss and ohmic loss. The results show that the performance change of the cell is dominantly influenced by the ohmic loss. Although the temperature and concentration distributions are different, the total activation loss and concentration loss are nearly same. And the ohmic loss is divided into each parts of the cell components. The ohmic loss of the anodic current collectorreaches about 60~80% of the cell's total ohmic loss. Therefore, the reduction of the ohmic loss of the anodic current collector is very important for stack power enhancement. It is also recommended that the load should be connected to the both ends of the anodic current collector.

• 설비공학논문집
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• 제20권3호
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• pp.197-204
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• 2008

DMFC(Direct Methanol Fuel Cell) is one of promising candidates for power sources of small mobile IT devices like notebook, cell phone, and so on. Efficient operation of fuel cell system is very important for long-sustained power supply because of limited fuel tank size. It is necessary to investigate operation characteristics of fuel cell stack for optimal control of DMFC system. The generated voltage was modeled according to various operating condition; methanol concentration, stack temperature, and load current. It is inevitable for methanol solution at anode to cross over to cathode through MEA(membrane electrode assembly), which reduces the system efficiency and increases fuel consumption. In this study, optimal operation conditions are proposed by analyzing stack performance model, cross-over phenomenon, and system efficiency.

• 한국수소및신에너지학회논문집
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• 제25권3호
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• pp.271-279
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• 2014

A 25kW-class polymer electrolyte membrane (PEM) fuel cell system has been developed for the propulsion of a leisure boat. The fuel cell system was designed to satisfy various performance requirements, such as resistance to shock, stability under rolling and pitching oscillations, and durability under salinity condition, for its marine applications. Then, the major components including a 30kW-class PEM fuel cell stack, a DC-DC converter, a seawater cooling system, secondary battery packs, and balance of plants were developed for the fuel cell system. The PEM fuel cell stack employs a unique design structure called an anodic cascade-type stack design in which the anodic cells are divided into several blocks to maximize the fuel utilization without hydrogen recirculation devices. The performance evaluation results showed that the stack generated a maximum power of 31.0kW while maintaining a higher fuel utilization of 99.5% and an electrical efficiency of 56.1%. Combining the 30-kW stack with other components, the 25kW-class fuel cell system boat was fabricated for a leisure. As a result of testing, the fuel cell system reached an electrical efficiency of 48.0% at the maximum power of 25.6kW with stable operability. In the near future, two PEM fuel cell systems will be installed in a 20-m long leisure boat to supply electrical power up to 50kW for propelling the boat and for powering the auxiliary equipments.

• 동력기계공학회지
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• 제13권3호
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• pp.11-19
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• 2009

This paper introduces a conceptual design of a combined scroll expander-compressor unit for a fuel cell. Since air discharged out of the fuel cell stack has still high pressure energy, some power can be extracted from the air by directing it to pass through an expanding device. Such extracted power can be used to drive an auxiliary compressor. For this purpose, a scroll type expander coupled to a scroll type compressor was designed for a 1kW-class fuel cell. The orbiting scroll members of the expander and the compressor were made to share three of common drive shafts installed in the mid frame plate. Performance analysis for the combined expander-compressor unit showed that the installation of this unit could reduce the auxiliary power consumption in the fuel cell by about 42%.

• Journal of Electrochemical Science and Technology
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• 제8권4호
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• pp.265-273
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• 2017

Solid-state alkaline water electrolysis is a promising method for producing hydrogen using renewable energy sources such as wind and solar power. Despite active investigations of component development for anion exchange membrane water electrolysis (AEMWE), understanding of the device performance remains insufficient for the commercialization of AEMWE. The study of assembled AEMWE devices is essential to validate the activity and stability of developed catalysts and electrolyte membranes, as well as the dependence of the performance on the device operating conditions. Herein, we review the development of catalysts and membranes reported by different AEMWE companies such as ACTA S.p.A. and Proton OnSite and device operating conditions that significantly affect the AEMWE performance. For example, $CuCoO_x$ and $LiCoO_2$ have been studied as oxygen evolution catalysts by Acta S.p.A and Proton OnSite, respectively. Anion exchange membranes based on polyethylene and polysulfone are also investigated for use as electrolyte membranes in AEMWE devices. In addition, operation factors, including temperature, electrolyte concentration and acidity, and solution feed methods, are reviewed in terms of their influence on the AEMWE performance. The reaction rate of water splitting generally increases with increase in operating temperature because of the facilitated kinetics and higher ion conductivity. The effect of solution feeding configuration on the AEMWE performance is explained, with a brief discussion on current AEMWE performance and device durability.

• 신재생에너지
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• 제1권4호
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• pp.49-54
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• 2005

There is close relation between the heat generation in the fuel cell stack and the fuel performance. In PEM fuel cell vehicles, the stack coolant temperature is about $65^{\circ}C$, which is far lower than that for general automobile engine. Therefore, it is hard to release heat generated in the stack by using a radiator of limited size because of the reduced temperature difference between the coolant and the ambient air. In this study, indirect stack cooling system using $CO_2$ heat pump was designed and its stack cooling performance in releasing heat to the ambient was investigated. This work focuses on a series of processes that grasp the relation among the fuel cell power, the radiator capacity and the stack temperature. The purpose of this work is to find out a way to properly release sufficient amount of heat through the finite sized radiator, so that the slack power generation can not be deteriorated due to the stack temperature increase. The optimization between the compressor power consumption and the fuel cell output power can be carried out to maximize the performance of fuel cell system.

• 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.