• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.101-104
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• 2006

Water management is considered to be one of the main issues to be addressed for the performance improvement of proton exchange membrane (PEM) fuel cell. For good water management, the detailed information on the water distribution inside an operating PEM fuel cell should be available to main an adequate level of hydration in the PEM While avoiding performance decline due to liquid rater flooding. For the PEM fuel cell to be commercially viable as vehicle applications, the flooding on the cathode side should be minimized during the fuel ceil operation. In this study to investigate cathode flooding and its relation with temperature distribution in flow channels, visualization study was performed on the cathode side of a PEM fuel cell. For the direct visualization of temperature field and water transport in cathode flow channels, a transparent cell was designed and manufactured using quartz window. Water transport and its two-phase flow characteristics in flow channels were investigated experimentally. Also, the visualization of temperature distribution In cathode flow channels was made by using IR camera. Results indicated that the temperature rise near the exit of cathode flow channel was found. It is found that this area corresponds to the flooding area from both temperature and flooding visualization results It is expected that this study can effectively contribute to get the detailed data on water transport linked with heat management during the operation of a PEM fuel cell

• International Journal of Automotive Technology
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• v.8 no.1
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• pp.119-126
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• 2007

Because of the low temperature operation, proton exchange membrane (PEM) fuel cell has a water phase transition. Therefore, water management is an important operation issue in a PEM fuel cell because the liquid water in the fuel cell causes electrode flooding that can lower the cell performance under high current density conditions. In this study, in order to understand the reactant distributions in the cathode channels of the PEM fuel cell, an experimental technique that can measure the species concentrations of reactant gases by using gas chromatograph (GC) is applied for an operating PEM fuel cell. The oxygen distribution along the cathode flow channels of PEM fuel cell is mainly investigated with various operating conditions. Also, the relations between cathode flooding and oxygen concentrations and oxygen consumption pattern along the cathode channel configurations of the unit cell adopted for this study are discussed using GC measurement and visualization experiment of cathode flooding. It is found that the amount of oxygen consumption is very sensitive to various operating conditions of the fuel cell and was much affected by the flooding occurrence in cathode channels.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.3
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• pp.355-360
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• 2012

The characteristics of power generation were investigated by changing the electrical conductivity from 10 to 40mS/cm using air-cathode microbial fuel cell, which had graphite fiber fabric(GFF) anode. There were three kinds of cathode used: one was carbon cloth cathode coated with Pt, another was carbon nanotube(CNT) cathode with non-precious catalyst of Fe-Cu-Mn, and the other was carbon nanotube(CNT) cathode without any catalyst. When it was operated in batch mode, power density of 1369.5mW/$m^2$ was achieved at conductivity of 20mS/cm. Power density from MFC with CNT cathode coated with multi-catalyst of Fe-Cu-Mn was shown about 985.55mW/$m^2$, which was 75.1% compared the power density of carbon cloth coated with Pt. This meant that CNT cathode coated with multi-catalyst of Fe-Cu-Mn could be an alternative of carbon cloth cathode.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.5 s.248
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• pp.489-495
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• 2006

Proton exchange membrane (PEM) should be sufficiently hydrated with a careful consideration of heat and water management. Water management has been a critical operation issue for better understanding the operation and optimizing the performance of a PEM fuel cell. The flooding on cathode side resulting from excess water can limit the fuel cell performance. In this study, the visual cell was designed and fabricated fur the visualization of liquid water droplet dynamics related to cathode flooding in flow channels. The experiment was carried out to observe the formation, growth and removal of water droplets using CCD imaging system. Effects of operating conditions such as cell temperature, air flow rate and air relative humidity on cathode flooding characteristics were mainly investigated. Based on this study, we can get the basic insight into flooding phenomena and its two-phase flow nature. It is expected that data obtained can be effectively used fur the setup and validation of two-phase PEM fuel cell models considering cathode flooding.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.04b
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• pp.1-5
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• 2000

As the semiconductor devices are miniaturized, the number of the unit cleaning processes increases. In order to processes by conventional RCA cleaning process, the consumption of volume of liquid chemical and DI water became huge. Therefore, the problem of environmental issues are evolved by the increased consumption of chemicals. To resolve this matter, an advanced cleaning process by Electrolyzed Water was studied in this work. The electrolyzed water was made by an electrolysis equipment which was composed of three chambers of anode, cathode, and middle chambers. In the case of electrolyzed water with electrolytes in the middle chamber, oxidatively acidic water of anode and reductively alkaline water of cathode were obtained. The oxidation/reduction potentials and pH of anode water and cathode water were measured to be +l000mV and 4.8, and -530mV and 6.3, respectively. The Si-wafers contaminated with metallic impurities were cleaning with the electrolyzed water. To analysis the amounts of metallic impurities on Si-water surfaces, ICP-MS(Inductively Coupled Plasma-Mass spectrometer) was introduced. From results of ICP-MS measurements, it was concluded that the ability of electrolyzed water was equivalent to that of the conventional RCA cleaning.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.326-329
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• 2005

Proton exchange membrane (PEM) should be sufficiently hydrated with proper water management to maintain a good ionic conductivity and performance of a PEM fuel cell. However. cathode flooding resulting from excess water can impede the transport of reactants and hence deteriorate the fuel cell performance. For the PEM fuel cell to be commercially viable as vehicle or portable applications, the flooding on the cathode side should be minimized during the fuel cell operation. In this study, visualization technique was applied to understand the cathode flooding phenomena on the cathode side of a PEM fuel cell. To this end. a transparent PEM unit fuel cell wi th an act ive area of $25cm^2$ was designed and manufactured to allow for the visualization of cathode channel with performance characteristics. Two-phase flow resulting from the electro-chemical reaction of fuel cell was investigated experimentally. The images photographed by CCD camera with cell operating temperatures $(30\~50^{\circ}C)$ were presented. Results indicated that the flooding on the cathode side first occurs near the exit of cathode channel. As the operating temperature of fuel cell increases. it was found that liquid water droplets tend to evaporate easily and it can have an influence on lowering the flooding level. It is expected that this study can effectively contribute to the detailed researches on modeling water transport of an operating PEM fuel cell including two-phase flow phenomena.

• Journal of Microbiology and Biotechnology
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• v.14 no.2
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• pp.324-329
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• 2004

Oxygen diffuses through the cation-specific membrane, reducing the coulomb yield of the fuel cell. In the present study, attempts were made to enhance current generation from the fuel cell by lowering the oxygen diffusion, including the uses of ferricyanide as a cathode mediator and of a platinum-coated graphite electrode. Ferricyanide did not act as a mediator as expected, but as an oxidant in the cathode compartment of the microbial fuel cell. The microbial fuel cell with platinum-coated graphite cathode generated a maximum current 3-4 times higher than the control fuel cell with graphite cathode, and the critical oxygen concentration of the former was 2.0 mg $1^{-1}$, whilst that of the latter was 6.6 mg $1^{-1}$. Based on these results, it was concluded that inexpensive electrodes are adequate for the construction of an economically feasible microbial fuel cell with better performance as a novel wastewater treatment process.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2250-2254
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• 2007

Comprehensive analytical models focusing on the anode water loss, the cathode flooding, water equilibrium, and water management strategy are developed for polymer electrolyte fuel cells. Analytical solutions presented in this study are compared with two-dimensional computational results and shows a good agreement in predicting those critical characteristics of water. General features of water concentration profile as a function of membrane thickness and current density are presented to illustrate the net effect of the back-diffusion of water from the cathode to anode and the water production by the cathode catalytic reaction on water transport over a fuel cell domain. As one of practical applications, the required humidity level of feed streams for full saturation at the channel outlets are investigated as a function of the physical operating condition. These analytical models can provide good understanding on the characteristic water

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.319-322
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• 2009

This paper investigated environmental effects for passive, air-breathing, and vapor-feeding direct methanol fuel cells. In these experiments, experimental parameters are temperature($30^{\circ}C$, $40^{\circ}C$ and relative humidity(25%, 50%, 75%). From these experimental results, the water contents play a key role in terms of optimal ionic conductivity at the cathode catalyst layer. In case of pure methanol feeding, the performance is inversely proportional to the relative humidity. The water generation resulting from methanol crossover maintains ionic conductivity at the cathode. On the contrary, diluted methanol solution (50wt.%) lowers methanol crossover to the cathode. In order to increase ionic conductivity, the relatively high humidity is required to the cathode catalyst layer for the water generation. The relative humidity scales with the performance.

• Journal of Environmental Science International
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• v.23 no.6
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• pp.1175-1182
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• 2014

In this study, we examined the effect of cathode from electrolysis reactor for treating ballast water. We are going to select a suitable cathode for seawater electrolysis after considering the effect on the generation of the oxidant of cathode and the electrode deposition materials adhering to the surface of cathode. Anode is Ru-Ti-Pd electrode and cathode are Ti, Pt, JP520 (Ni-Pt-Ce) electrodes. Using the cathode of the three types, experiments were conducted to examine the effects of TRO (total residual oxidants) generation concentration and RNO (N, N-Dimethyl-4-nitrosoaniline, indicator of the generation of OH radical) degradation concentration (in 1, 35 psu), ohmic drop, FESEM(field emission scanning electron microscope) observation of cathode surface and EDX (energy dispersive X-ray spectroscopy) measurements of attached fouling material. The results showed that TRO generation concentration and RNO degradation concentration in according to each type of cathode are not different. The attached fouling materials were observed on the surface of Ti and the JP520 electrode by the observation of SEM after electrolysis for two hours, but it was not observed on the surface of Pt electrode. When considering the surface ohmic drop of cathode and the attached fouling materials, Pt electrode was judged as the excellent cathode.