• 한국군사과학기술학회지
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• 제15권4호
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• pp.519-526
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• 2012

Recently fuel cell is considered to be a new technology that can substitute the ICE(Internal Combustion Engine) as well as overcome environmental issues. In military applications, fuel cell has an unique advantages, which are quietness, namely, stealth. The environmental requirement such as shock and vibration in military application, however, is very severe comparing to civilian demand. Especially, the safety concerning hydrogen storage is the most important problem. Among the candidate methods to store hydrogen, the metal hydride storage is promising method owing to the storage mechanism of chemical absorption of hydrogen to metal hydrides. In this study, the new composition of Ti-Zr type metal hydride(A composition) was suggested and investigated to increase the hydrogen storage capacity. For comparison, the hydrogen charge-discharge properties were investigated with the commercialized Ti-Zr type metal hydride(B composition) using PCT(Pressure-Composition-Temperature) measurement. Also two hydrogen storage cylinders were loaded with each metal hydride and their hydrogen charging and discharging characteristics were investigated. As a result, it was found that the new Ti-Zr type metal hydride has a slightly higher hydrogen storage capacity compared to commercial Ti-Zr type metal hydride.

• 공업화학
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• 제33권6호
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• pp.646-652
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• 2022

Dead ended anode (DEA) 시스템은 수소극(anode) 출구를 막고 압력으로 연료를 공급하는 방식이다. DEA 방식은 시스템 단순화를 통해 연료이용효율과 전력 효율을 향상시킬 수 있다. 하지만 DEA 운전 중 공기극(cathode)에서 수소극으로 질소와 물의 역확산으로 인한 범람(flooding)이 발생한다. 이러한 범람 현상은 연료전지 성능 저하와 전극 열화의 주요 요인이 된다. 따라서 DEA 운전 시 범람을 방지하기 위하여 연료전지 구조와 구성요소가 최적화되어야 한다. 본 연구에서는 DEA 시스템에서 연료전지의 성능과 연료이용효율 향상을 위해 발포 금속을 적용한 다공성 유로에 대한 영향을 조사하였다. 그 결과, 공기극에 다공성 유로를 사용한 경우 효과적인 물 관리로 연료전지 성능과 배출 간격(purge interval)이 개선되었고, 이를 통하여 공기극 유로 구조가 물 역확산에 영향을 미치는 것을 확인하였다. 이에 반해 수소극의 다공성 유로가 연료전지 성능에 미치는 영향은 미미하였다. DEA 시스템에서는 발포 금속 물성이 배출 간격에 영향을 미치며 cell 크기가 큰 발포 금속에서 안정적인 성능을 나타내었다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2011년도 제37회 추계학술대회논문집
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• pp.451-454
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• 2011

수중에서 추진되는 초고속 로켓 모터에 적용이 가능한 해수반응 금속연료 (Hydro-Reactive metal Fuel, 이하 HRF) 추진제는 연료의 적재량을 증가시키기 위해 채용하는 추진제이다. 하지만, 현재까지 HRF 추진제에 대한 연소속도 측정 기술 개발에 대한 연구는 미비한 상태이다. 본 연구팀은 연소 속도를 측정하는 기법들 중, 한 번의 실험으로 압력 변화에 따른 연소속도 측정이 가능한 초음파 법을 개발하여 고체 추진제의 연소속도를 측정하고 신뢰성을 검증하였다. 본 논문에서는 기 개발된 시스템을 이용하여 HRF 추진제의 연소 속도를 측정하였다.

• 한국정밀공학회지
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• 제33권4호
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• pp.279-286
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• 2016

To enhance the safety of nuclear reactors after the Fukushima accident, researchers are developing various types of accident tolerant fuel (ATF) to increase the coping time and reduce the generation of hydrogen by oxidation. Coated cladding, an ATF concept, can be a promising technology in view of its commercialization. We applied 3D printing technology to the fabrication of coated cladding as well as of coated pellets. Direct metal tooling (DMT) in 3D printing technologies can create a coated layer on the tubular cladding surface, which maintains stability during corrosion, creep, and wear in the reactor. A 3D laser coating apparatus was built, and parameter studies were carried out. To coat pellets with erbium using this apparatus, we undertook preliminary experiments involving metal pellets. The adhesion test showed that the coated layer can be maintained at near fracture strength.

• 한국자동차공학회논문집
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• 제22권4호
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• pp.65-71
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• 2014

As an important component of a fuel cell, the bipolar plate comprises a large proportion in the fuel cell's volume, weight and price. The bipolar plate is the most widely used; however, graphite bipolar plate is large in volume, brittle and therefore easily broken during assembling. In addition, due to its poor machinability, production costs a lot, unless mass production. Compared with the graphite bipolar plate, the metal bipolar plate has good machinability, high electric conductivity and strong mechanical strength; however, it corrodes easily and has a high contact resistance, so in order to prevent corrosion and reduce the contact resistance, the basic metal needs to be processed by use of electro polishing and coating. The water which is produced by electrochemical reactions in the fuel cell must be discharged smoothly. In this study, in order to prevent corrosion the processes of electro polishing and CrN coating were used. According to the presence or absence of these processes, the contact angles can be measured and different metal bipolar plates can be made, these plates can be used for comparing and analyzing the performance of the fuel cell.

• Journal of Electrochemical Science and Technology
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• 제15권2호
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• pp.207-219
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• 2024

Metal-N-C (MNC) catalysts have been anticipated as promising candidates for oxygen reduction reaction (ORR) to achieve low-cost polymer electrolyte membrane fuel cells. The structure of the M-N_x moiety enabled a high catalytic activity that was not observed in previously reported transition metal nanoparticle-based catalysts. Despite progress in non-precious metal catalysts, the low density of active sites of MNCs, which resulted in lower single-cell performance than Pt/C, needs to be resolved for practical application. This review focused on the recent studies and methodologies aimed to overcome these limitations and develop an inexpensive catalyst with excellent activity and durability in an alkaline environment. It included the possibility of non-precious metals as active materials for ORR catalysts, starting from Co phthalocyanine as ORR catalyst and the development of methodologies (e.g., metal-coordinated N-containing polymers, metal-organic frameworks) to form active sites, M-N_x moieties. Thereafter, the motivation, procedures, and progress of the latest research on the design of catalyst morphology for improved mass transport ability and active site engineering that allowed the promoted ORR kinetics were discussed.

• 전기학회논문지P
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• 제63권3호
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• pp.212-217
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• 2014

The electric power output characteristics of magnesium fuel cell were investigated with regard to internal resistance. A equivalent circuit with the series-connected three internal resistance was introduced to analyze of the response to change of power. The power output analysis was employed in order to investigate the effect of internal resistances for the electrolyte concentration, air electrode area, Mg electrode area and distance between the electrodes. It was confirmed that internal resistance is generated by the electrolyte, air electrode and metal electrode, then those Internal resistances had a significant effect on the power output decrease. The power output was a maximum when the load resistance maches the internal resistance of the magnesium fuel cell. The fuel efficiency was only 50% at maximum power output. Higher fuel efficiency was achieved when the load resistance is greater than the internal resistance.

• Nuclear Engineering and Technology
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• 제50권1호
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• pp.80-87
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• 2018

Consideration is given to the possibility to use changes in buoyancy as a negative reactivity feedback mechanism during temperature transients in heavy liquid metal fast reactors. It is shown that by the proper use of heavy pellets in the fuel elements, fuel rods could be endowed with a passive self-ejection mechanism and then with a negative feedback. A first estimate of the feasibility of the mechanism is calculated by using a simplified geometry and model. If in addition, a neutron poison pellet is introduced at the bottom of the fuel, then when the fuel element is displaced upward by buoyancy force, the reactivity will be reduced not only by disassembly of the core but also by introducing the neutron poison from the bottom. The use of induced buoyancy opens up the possibility of introducing greater amounts of actinides into the core, as well as providing a palliative solution to the problem of positive coolant temperature reactivity coefficients that could be featured by the heavy liquid metal fast reactors.

• 융복합기술연구소 논문집
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• 제3권2호
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• pp.1-6
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• 2013

The ionic liquids are known to potential alternative solvents capable of replacing the commercial solvents in various processes including those in nuclear fuel cycle. As to the material, a number of studies have already reviewed the interesting results and addressed the spectroscopic as well as electrochemical behaviors of metal elements included in spent nuclear fuels. It has found that the important properties of metal ions in TBP dissolved ILs have led the development of alternative technologies to traditional solvent extraction processes. On the other hand, the electrochemical deposition of metal ions in ILs have been investigated for the application of the solvents to aqueous as well as to non-aqueous processes. In this work, a review on the application of ILs in nuclear fuel cycle is briefly presented to understand the notable researches on ILs focusing on aqueous processes.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.82.2-82.2
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• 2010

The development of bipolar plate having high efficiency and chemical properties has a major impact on fuel cell applications commercialization. Even though graphite bipolar plate has high electric conductivity and chemical resistance, it has demerits about mass production and brittle property for commercialization. Hence, metallic bipolar plate can be substitute for fuel cell bipolar plate. Although its inadequate corrosion behavior under PEMFC environment lead to a deterioration of membrane by dissolved metal ions, metallic bipolar plate for PEMFC is more suitable for automotive and residential power generation system because of its high mechanical strength, low gas permeability and applicability to mass production. Therefore, several types of coating has been applied to prevent corrosion and oxide film growth and to achieve more high durability. This work presents durability of coated metal bipolar plate for low temperature PEMFC which made for fuel cell vehicle. This results showed surface treatment increase long-term durability, even electric conductivity and corrosion resistance.