• Proceedings of the Membrane Society of Korea Conference
• /
• 2005.11a
• /
• pp.204-207
• /
• 2005

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.34 no.7
• /
• pp.715-720
• /
• 2010

We propose an electroosmosis-based air delivery scheme for polymer electrolyte fuel cells and experimentally investigate its feasibility. An electroosmotic pump under a low-frequency AC electric field is used to displace initially a volume of pump working liquids. This working liquid is then pumped into a space enclosed by a flexible membrane and the movement of the membrane delivers air to a fuel cell. We successfully demonstrated the operation of a forced-convection fuel cell using this technique. In this preliminary study, however, the power consumption of the pump exceeds the power generated by the fuel cell. We conclude this paper with a discussion of several ways to reduce the pump-to-fuel cell power ratio.

• Macromolecular Research
• /
• v.14 no.4
• /
• pp.449-455
• /
• 2006

Ionic cluster mimic, polymer electrolyte membranes were prepared using polymer composites of crosslinked poly(vinyl alcohol) (PVA) with sulfated-${\beta}$-cyclodextrins (${\beta}-CDSO_3H$) or phosphated-${\beta}$-cyclodextrins (${\beta}-CDPO(OH)_2$). When Nafion, developed for a fuel cell using low temperature, polymer electrolyte membranes, is used in a direct methanol fuel cell, it has a methanol crossover problem. The ionic inverted micellar structure formed by micro-segregation in Nafion, known as ionic cluster, is distorted in methanol aqueous solution, resulting in the significant transport of methanol through the membrane. While the ionic structure formed by the ionic sites in either ${\beta}-CDSO_3H$ or ${\beta}-CDPO(OH)_2$ in this composite membrane is maintained in methanol solution, it is expected to reduce methanol transport. Proton conductivity was found to increase in PVA membranes upon addition of ionized cyclodextrins. Methanol permeability through the PVA composite membrane containing cyclodextrins was lower than that of Nafion. It is thus concluded that the structure and fixation of ionic clusters are significant barriers to methanol crossover in direct methanol fuel cells.

• Journal of Power Electronics
• /
• v.11 no.1
• /
• pp.82-89
• /
• 2011

Differences in the frequency characteristic applied to a ripple current may shorten fuel cell life span and worsen the fuel efficiency. Therefore, this paper presents an experimental analysis of the ripple current applied variable frequency characteristic in a polymer electrolyte membrane fuel cell (PEMFC). This paper provides the first attempt to examine the impact of ripple current through immediate measurements on a single cell test. After cycling for hours at three frequencies, each polarization and impedance curve is obtained and compared with those of a fuel cell. Through experimental results, it can be absolutely concluded that low frequency ripple current leads to long-term degradation of a fuel cell. Three different PEMFC failures such as membrane dehydration, flooding and carbon monoxide (CO) poisoning that lead to an increase in the impedance magnitude at low frequencies are simply introduced.

• Journal of Hydrogen and New Energy
• /
• v.11 no.1
• /
• pp.19-27
• /
• 2000

The polymer electrolyte membrane fuel cell (PEMFC) system was developed. In order to enhance the performance of membrane electrode assembly (MEA), the transfer printing method of the electrocatalyst layer on membrane was developed. The $H_2/O_2$ single cell with an electrode area of $50cm^2$ was fabricated and tested using 20 wt.% Pt/C as an electrocatalyst and the commercial and hand-made MEA such as Nafion 115, Hanwha, Dow, Flemion T and Gore Select. The 100-cell PEMFC stack with an active electrode area of $300cm^2$ was designed and fabricated using 40 wt.% Pt/C and 30 wt.% Pt-Ru/C as a cathode and anode electrocatalysts, respectively. The performance of PEMFC system was obtained to be 7kW (250A at 28V) and 3.5kW (70A at 50V) at $80^{\circ}C$ by flowing $H_2/air$ and methanol reformed fuel gas/air, respectively.

• Journal of Microbiology and Biotechnology
• /
• v.23 no.1
• /
• pp.36-39
• /
• 2013

We introduce a high-performance microbial fuel cell (MFC) that was operated using a 0.1M bicarbonate buffer as the cathodic electrolyte. The MFC had a 136.42 $mW/m^2$ maximum power density under continuous feeding of 5 mM acetate as fuel. Results of the electrode potential measurements showed that the cathode potential of the bicarbonate-buffered condition was higher than the phosphate-buffered condition, although the phosphate condition had less interfacial resistance between the membrane and electrolyte. Therefore, we posit here that the increased power of the bicarbonate-buffered MFC may be caused by the higher cathode potential rather than by the interfacial membrane-electrolyte resistance.

• Bulletin of the Korean Chemical Society
• /
• v.31 no.8
• /
• pp.2141-2142
• /
• 2010

• Journal of Hydrogen and New Energy
• /
• v.23 no.1
• /
• pp.26-33
• /
• 2012

Phosphoric acid-doped poly (2,5-benzimidazole) (DABPBI) was prepared by condensation polymerization of 3,4-diaminobenzoic acid for high temperature proton electrolyte membrane fuel cells. The membranes were casted directly using a hot-press unit and characterized by fourier transform infrared spectroscopy, thermogravimetric analysis, conductivity measurement, scanning electron microscopy and tensile test. The proton conductivities of DABPBI are observed to be 0.062 and 0.018 $S{\cdot}cm^{-1}$ under 30 and 1% relative humidity, respectively at a temperature of $120^{\circ}C$ which is appreciably higher than that of Nafion 115 under similar conditions. The DABPBI membrane has demonstrated excellent thermo- mechanical properties and proton conductivity suggesting its suitability as a high temperature membrane.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.20 no.4
• /
• pp.528-535
• /
• 2017

Fuel cells have been spotlighted in the world for being highly efficient and environmentally friendly. A hydrogen which is the fuel of fuel cell can be obtained from a number of sources. Hydrogen source for operating the polymer electrolyte membrane fuel cell(PEMFC) in the current underwater environment, such as a submarine and unmanned underwater vehicles are currently from the metal hydride cylinder. However, metal hydride has many limitations for using hydrogen carrier, such as large volume, long charging time, limited storage capacity. To solve these problems, we suggest diesel reformer for hydrogen supply source. Diesel fuel has many advantages, such as high hydrogen storage density, easy to transport and also well-infra structure. However, conventional diesel reforming system for PEMFC requires a large volume and complex CO removal system for lowering the CO level to less than 10 ppm. In addition, because the preferential oxidation(PROX) reaction is the strong exothermic reaction, cooling load is required. By changing this PROX reactor to hydrogen separation membrane, the problem from PROX reactor can be solved. This is because hydrogen separation membranes are small and permeable to pure hydrogen. In this study, we conducted the pressurized diesel reforming and water-gas shift reaction experiment for the hydrogen separation membrane application. Then, the hydrogen permeation experiments were performed using a Pd alloy membrane for the reformate gas.

• Journal of the Korean Ceramic Society
• /
• v.42 no.12 s.283
• /
• pp.865-871
• /
• 2005

Submicron thick solid electrolyte membrane is essential to the implementation of low temperature solid oxide fuel cell, and, therefore, development of new electrode structures is necessary for the submicron thick solid electrolyte deposition while providing functions as current collector and fuel transport channel. In this research, a nickel membrane with multi-stage nano hole array has been produced via modified two step replication process. The obtained membrane has practical size of 12mm diameter and $50{\mu}m$ thickness. The multi-stage nature provides 20nm pores on one side and 200nm on the other side. The 20nm side provides catalyst layer and $30\~40\%$ planar porosity was measured. The successful deposition of submicron thick yttria stabilized zirconia membrane on the substrate shows the possibility of achieving a low temperature solid oxide fuel cell.