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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Transactions of the Korean hydrogen and new energy society
Journal Basic Information
Journal DOI :
The Korean Hydrogen and New Energy Society
Editor in Chief :
Volume & Issues
Volume 15, Issue 4 - Dec 2004
Volume 15, Issue 3 - Sep 2004
Volume 15, Issue 2 - Jun 2004
Volume 15, Issue 1 - Mar 2004
Selecting the target year
Energy management strategies of a fuel cell/battery hybrid system using fuzzy logics
Jeong, Kwi-Seong ; Lee, Won-Yong ; Kim, Chang-Soo ;
Transactions of the Korean hydrogen and new energy society, volume 15, issue 1, 2004, Pages 1~11
Hybrid power systems with fuel cells and batteries have the potential to improve the operation efficiency and dynamic response. A proper load management strategy is important to better system efficiency and endurance in hybrid systems. In this paper, a fuzzy logic algorithm has been used to determine the fuel cell output power depending on the external required power and the battery state of charge(SoC). If the required power of the hybrid system is small and the SoC is small, then the greater part of the fuel cell power is used to charge the battery pack. If the required power is relatively big and the SoC is big, then fuel cell and battery are concurrently used to supply the required power. These IF-THEN operation rules are implemented by fuzzy logic for the energy management system of hybrid system. The strategy is evaluated by simulation. The results show that fuzzy logic can be effectively used to optimize the operational efficiency of hybrid system and to maintain the battery SoC properly.
Effects of propane substitution for safety improvement of hydrogen-air flame
Kwon, Oh-Chae ;
Transactions of the Korean hydrogen and new energy society, volume 15, issue 1, 2004, Pages 12~22
In order to evaluate the potential of partial hydrocarbon substitution to improve the safety of hydrogen use in general and the performance of internal combustion engines in particular, the outward propagation and development of surface cellular instability of spark-ignited spherical premixed flames of mixtures of hydrogen, hydrocarbon, and air were experimentally studied at NTP (normal temperature and pressure) condition in a constant-pressure combustion chamber. With propane being the substituent, the laminar burning velocities, the Markstein lengths, and the propensity of cell formation were experimentally determined, while the laminar burning velocities and the associated flame thicknesses were computed using a recent kinetic mechanism. Results show substantial reduction of laminar burning velocities with propane substitution, and support the potential of propane as a suppressant of both diffusional-thermal and hydrodynamic cellular instabilities in hydrogen-air flames.
Development of Bifunctional Electrocatalyst for PEM URFC
Yim, Sung-Dae ; Park, Gu-Gon ; Sohn, Young-Jun ; Yang, Tae-Hyun ; Yoon, Young-Gi ; Lee, Won-Yong ; Kim, Chang-Soo ;
Transactions of the Korean hydrogen and new energy society, volume 15, issue 1, 2004, Pages 23~31
For the fabrication of high efficient bifunctional electrocatalyst of oxygen electrode for PEM URFC (Polymer Electrolyte Membrane Unitized Regenerative Fuel Cell), which is a promising energy storage and conversion system using hydrogen as the energy medium, several bifunctional electrocatalysts were prepared and tested in a single cell URFC system. The catalysts for oxygen electrode revealed fuel cell performance in the order of Pt black > PtIr > PtRuOx > PtRu ~ PtRuIr > PtIrOx, whereas water electrolysis performance in the order of PtIr ~ PtIrOx > PtRu > PtRuIr > PtRuOx ~ Pt black. Considering both reaction modes PtIr was the most effective elctrocatalyst for oxygen electrode of present PEM URFC system. In addition, the water electrolysis performance was significantly improved when Ir or IrOx was added to Pt black just 1 wt.% without the decrease of fuel cell performance. Based on the catalyst screening and the optimization of catalyst composition and loading, the optimum catalyst electrodes for PEM URFC were
of Pt black as hydrogen electrode and
of PtIr (99:1) as oxygen electrode.
Thermal Behaviors of (Cu
production by thermochemical cycles
Kim, J.W. ; Choi, S.C. ; Joo, O.S. ; Jung, K.D. ;
Transactions of the Korean hydrogen and new energy society, volume 15, issue 1, 2004, Pages 32~38
Thermal behaviors of
, prepared by a solid method, were investigated for
production by a thermochemical cycle. The thermal reduction of
and the weight loss was 1.3 wt% up to 1200. XRD shows the prepared ferrite has the spinel structure with a lattice constant of
and changed to the oxygen deficient structure by thermal reduction. Oxygen and hydrogen can be separately produced by the cycles of thermal reduction and water oxidation of the oxygen deficient ferrite.
Performance of a 1 kW PEMFC Stack Using the TiN-Coated 316 Stainless Steel Bipolar Piates
Jeon, U.-S. ; Jo, E.-A. ; Ha, H.Y. ; Hong, S.-A. ; Oh, I.-H. ;
Transactions of the Korean hydrogen and new energy society, volume 15, issue 1, 2004, Pages 39~45
A 12-cell PEMFC stack was fabricated using the TiN-coated 316 stainless steel bipolar plates as substitute for the expensive and brittle graphite bipolar plates. Open cirtuit voltage and the maximum power of the stack was 12.08 V and 1.197 kW (199.5 A @ 6 V), respectively. Volumetric and gravimetric power density of the stack was calculated to be 373 W/L and 168 W/kg, respectively. Performance of each cell was quite uniform initially while degraded at a singnificantly different rate. During the 1,000 hr-operation at a constant load of 48 A, stack voltage decreased from 9.0 to 7.98 V at a degradation rate of 11 %/1,000 hr. However, degradation rate of each cell was in the wide rage from 1.2 to 31 %/1,000 hr.
Redox Characteristics of Cobalt Oxide based Oxygen Carriers for Chemical-Looping Combustion
Lee, J.B. ; Park, C.S. ; Choi, S.I. ; Song, Y.W. ; Yang, H.S. ; Kim, Y.H. ;
Transactions of the Korean hydrogen and new energy society, volume 15, issue 1, 2004, Pages 46~53
Redox characteristics of cobalt oxide-based oxygen carriers were tested for chemical-looping combustion. Cobalt oxide was chosen as active metal oxide and
was compared with YSZ(yttria-stabilized zirconia) as a binder. Cobalt oxide/
was prepared by sol-gel method. Hydrogen fuel was reacted with metal oxide and then the reduced metal was successively oxidized by air. The effects of reaction temperature were measured and the regenerabilies during 10 cycles were examined by a TGA. In regenerability of cobalt oxide/YSZ and cobalt oxide/
, after they showed above 90% conversion in first reduction, they were stabilized in about 70-75% conversion. From reaction rate constant obtained, the activation energies of cobalt oxide/YSZ in oxidation and reduction were 51.47kJ/mol and 7.71kJ/mol respectively.
Temperature Characteristics of the Molten Carbonate Fuel Cell Stack
Lee, Choong-Gon ; Ahn, Kyo-Sang ; Park, Seong-Yeon ; Seo, Hai-Kyung ; Lim, Hee-Chun ;
Transactions of the Korean hydrogen and new energy society, volume 15, issue 1, 2004, Pages 54~61
Temperature characteristics in a stack of molten carbonate fuel cell (MCFC) have been investigated with simulation based on the computational fluid dynamics (CFD) codes and experimental way. The MCFC has generally two stack structures when the natural gas is used as fuel; one is the external reforming type and the other is internal reforming type. Computer simulation at the external reforming stack suggests that the maximum temperature in the stack depends on the gas flow length. The 2 kW MCFC stack with 25 cm gas flow length showed about
of maximum temperature.
Syntheses of LiMn
and Electrochemical Properties of their Mixtures for Lithium Secondary Battery
Kwon, IkHyun ; Kim, HunUk ; Song, MyoungYoup ;
Transactions of the Korean hydrogen and new energy society, volume 15, issue 1, 2004, Pages 62~71
Analysis of Sodium Spray Fire Using Gaussian Droplet Size Distribution
Kim, B.H. ; Hahn, D.H. ; Suh, S.H. ;
Transactions of the Korean hydrogen and new energy society, volume 15, issue 1, 2004, Pages 72~81
Study on the analysis of sodium spray fire using Gaussian drop size distribution, which redistributes a droplet spectrum with given mean diameter if its size classes with critical diameter(D>8mm) occur, was carried out. In this case, the oversized droplets were reduced to a stable diameter. Results calculated by the code using Gaussian drop size distribution were in better agreement with AI experimental results than those of NACOM and SPRAY code. The effect of variance on pressure in the test cell appeared greatly by introducing Gaussian function, which could represent various sodium droplet size distribution. The increase of the variance with mean droplet size resulted had an important effect upon the pressure in the test cell.
Analysis of Hydrogen Accident in Korea
Jo, Young-Do ; Tak, Song-Su ; Choi, Kyoung-Suhk ; Lee, Jong Rark ; Park, Kyo-Shik ;
Transactions of the Korean hydrogen and new energy society, volume 15, issue 1, 2004, Pages 82~87
Hydrogen is considered to be the most important future energy carrier in many applications reducing greenhouse gas emissions significantly. To be applicable as energy carrier the safety issues associated with hydrogen applications needs to be investigated and fully understood. In order to analyze the risks associated with hydrogen applications, accidents associated with hydrogen in Korea from 1963 to 2002 have been analysed in this work. From analysis of accidents, we propose the necessity of research on hydrogen releases, dispersion in air, and explosion due to high hazardous of hydrogen.