• Transactions of the Korean hydrogen and new energy society
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• v.27 no.2
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• pp.163-168
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• 2016

Korea has been developing nuclear fusion fuel storage and delivery system (SDS) technologies including a basic scientific study on hydrogen storage. To develop nuclear fusion technology, it is necessary to store and supply hydrogen isotopes needed for Tokamak operation. SDS is used for storing hydrogen isotopes as a metal hydride form. The rapid hydriding of tritium is very important not only for safety reasons but also for the economic design and operation of the SDS. In this study, we designed and fabricated a medium-scale getter bed of depleted uranium (DU). The hydriding of DU has been measured by varying the initial temperature ($100-300^{\circ}C$) of the DU getter bed to investigate the influence of the cooling temperature. Furthermore, we analyzed the effect of a helium blanket on the hydriding performance with 0 - 12% helium content in hydrogen.

• Transactions of the Korean hydrogen and new energy society
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• v.33 no.2
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• pp.158-163
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• 2022

The test method on the Type II high-pressure hydrogen storage tanks made of the metal wire hoop winding is a complex and high risk. Also closeup on the tank being test is difficult. In this study, we studied a mechanical test method for a high-pressure hydrogen tanks. This method must be simple, risk-free and possible to observe the change in microscopic behavior of a metal wire on a liner. As the results, it was possible to observe the microscopic behavior on the metal wire by the mechanical test method. Also, a simple and risk-free test was possible compared to the conventional test method for high pressure hydrogen tanks.

• Transactions of the Korean hydrogen and new energy society
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• v.4 no.1
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• pp.31-39
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• 1993

In order to improve the hydrogen storage capacity and the activation property of the $MmNi_{4.5}Al_{0.5}$ alloy, the multiphase alloy system are prepared by adding the excess Zr in $MmNi_{4.5}Al_{0.5}$ alloy. It is estimated from the X-ray diffraction pattern and the energy dispersive X-ray analysis that the 2nd phases in $MmNi_{4.5}Al_{0.5}Zr_x$ alloys are $ZrNi_3$, ${\beta}$-Zr. Their morphology is also examined by the scanning electron microscope, and it shows the needle-like precipitation. As the Zr contents increase, the activation time and the plateau pressure decrease, sloping of the plateau pressure increase. Amount of the 2nd phases increase with Zr contents in $MmNi_44.5Al_{0.5}Zr_x$ alloys. The $MmNi_44.5Al_{0.5}Zr_{0.05}$ alloy, which shows the maximum storage capacity and the strong resistance to intrinsic degradation, is considered as a proper alloy for hydrogen storage.

• Progress in Superconductivity and Cryogenics
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• v.15 no.2
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• pp.1-8
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• 2013

This paper reviews the development status of magnetic refrigeration system for hydrogen liquefaction. There is no doubt that hydrogen is one of most important energy sources in the near future. In particular, liquid hydrogen can be utilized for infrastructure construction consisting of storage and transportation. Liquid hydrogen is in cryogenic temperatures and therefore high efficient liquefaction method must be studied. Magnetic refrigeration which uses the magneto-caloric effect has potential to realize not only the higher liquefaction efficiency > 50 %, but also to be environmentally friendly and cost effective. Our hydrogen magnetic refrigeration system consists of Carnot cycle for liquefaction stage and AMR (active magnetic regenerator) cycle for precooling stages. For the Carnot cycle, we develop the high efficient system > 80 % liquefaction efficiency by using the heat pipe. For the AMR cycle, we studied two kinds of displacer systems, which transferred the working fluid. We confirmed the AMR effect with the cooling temperature span of 12 K for 1.8 T of the magnetic field and 6 second of the cycle. By using the simulation, we estimate the total efficiency of the hydrogen liquefaction plant for 10 kg/day. A FOM of 0.47 is obtained in the magnetic refrigeration system operation temperature between 20 K and 77 K including LN2 work input.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.2
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• pp.105-113
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• 2015

In order to accelerate hydrogen society in current big renewable energy trend, it is very important that hydrogen can be transported and stored as a fuel in efficient and economical fashion. In this perspective, liquid hydrogen can be considered as one of the most prospective storage methods that can bring early arrival of the hydrogen society by its high gravimetric energy density. In this study, a small-scale hydrogen liquefier has been designed and developed to demonstrate direct hydrogen liquefaction technology. Gifford-McMahon (GM) cryocooler was employed to cool warm hydrogen gas to normal boiling point of hydrogen at 20K. Various cryogenic insulation technologies such as double walled vacuum vessels and multi-layer insulation were used to minimize heat leak from ambient. A liquid nitrogen assisted precooler, two ortho-para hydrogen catalytic converters, and highly efficient heat pipe were adapted to achieve the target liquefaction rate of 1L/hr. The liquefier has successfully demonstrated more than 1L/hr of hydrogen liquefaction. The system also has demonstrated its versatile usage as a very efficient 150L liquid hydrogen storage tank.

• Transactions of the Korean hydrogen and new energy society
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• v.21 no.4
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• pp.340-345
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• 2010

For the conversion into hydrogen society, not only studying facilities of hydrogen production, storage, transportation and charging system but also developing technique of ensuring safety are essentially needed. Hence, for the first step of that, evaluated the hydrogen embrittlement of Inconel alloy 617, Ni-based super heat-resisting alloy, by small punch test. Prepared the various specimens through changing electrochemical charging time and measured the toughness degradation of the specimens by small-punch test. The analysis of hydrogen embrittlement behavior were carried out by investigating the fractured surface of specimens. This study has significance on revealing mechanism of hydrogen embrittlement behavior and the factor affecting hydrogen embrittlement in the future study.

• New & Renewable Energy
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• v.3 no.2 s.10
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• pp.60-67
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• 2007

This paper describes the design and integration of the wind-fuel cell hybrid system. The hybrid system components included a wind turbine, an electrolyzer (for generation of H2), a PEMFC (Proton Exchange Membrane Fuel Cell), hydrogen storage tank and BOP (Balance of Plant) system. The energy input is entirely provided by a wind turbine. A DC-DC converter controls the power input to the electrolyzer, which produces hydrogen and oxygen form water. The hydrogen used the fuel for the PEMFC. Hydrogen may be produced and stored in high pressure tank by hydrogen gas booster system. Wind conditions are changing with time of day, season and year. So, wind power is a variable energy source. The main purpose with these WT-FC hybrid system is to store hydrogen by electrolysis of water when wind conditions are good and release the stored hydrog en to supply the fuelcell when wind is low.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.219-221
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• 2011

This paper reports the development trend of small fuel cell unmanned aerial vehicles. Development method of a fuel cell propulsion system for small unmanned aerial vehicles is proposed and discussed, such as the lightweight fuel cell stack development, liquid fuel-based hydrogen storage/generation, and fuel cell system technology.

• Transactions of the Korean hydrogen and new energy society
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• v.18 no.4
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• pp.413-421
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• 2007

In this paper, the performance characteristics of heat pump system using a new refrigerant subcooling system designed for the study, are introduced. The new heat pump system have the ice storage tank at the outlet of condenser. The experimental apparatus is a well-instrumented water/water heat pump which consisted of working fluid loop, coolant loop, and ice storage tank. The experiment parameters of subcooling ranged as the evaporating temperature from $-5^{\circ}C$ to $8^{\circ}C$, the condensing temperature from $30^{\circ}C$ to $35^{\circ}C$. The test of the ice storage was carried out at evaporating temperature of $-10^{\circ}C$ and the ice storage mode is Ice-On-Coil type. The working fluid was R-22 and the storage materials were city-water. The test results obtained were as follows; The refrigerant mass flow rate and compressor shaft power were unchanged by the degrees of subcooling, that is, they were independent of degrees of subcooling. The cooling capacity of the new heat pump system increase as the evaporating temperature and subcooling degrees increase and is higher by $25{\sim}30%$, compared to the normal heat pump system. The COP of the new heat pump system increases as the degrees of subcooling and evaporating temperature increase and is higher by 28% than that of the normal heat pump system.

• Transactions of the Korean hydrogen and new energy society
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• v.30 no.1
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• pp.14-20
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• 2019

The power to gas (P2G) is one of the energy storage technologies that can increase the storage period and storage capacity compared to the existing battery type. One of P2G technologies produces hydrogen by decomposing water from renewable energy (electricity) and the other produces $CH_4$ by reacting hydrogen with $CO_2$. The objective of this study is the reaction of $CO_2$ methanation which synthesized methane by reacting carbon dioxide and hydrogen. The effect of $CO_2$ conversion and $CH_4$ selectivity on reaction temperature, pressure, and methane contents over 40% Ni catalyst was mainly investigated throughout this study. As a result, the activity of this catalyst appeared to be the highest in $CH_4$ yield at around $400^{\circ}C$ and the selectivity of $CH_4$ increased with increasing reaction pressure. The methane content was not significantly influenced below 3% of all componets. As the space velocity increases from 10,000 to 30,000/hr, the $CO_2$ conversion rate tends to decrease.