• 한국수소및신에너지학회논문집
• /
• 제19권4호
• /
• pp.299-304
• /
• 2008

Thermal decomposition of Ammonia Borane have been investigated with various analytical methods including TGA, TP-MS, DSC. By-products such as aminoborane and borazine were identified during hydrogen release by TGA, TP-MS analysis. $H_2$ release amount was measured at each temperature isothermally, which resulted in 7 wt% $H_2$ release at 130$^{\circ}C$. Moreover, higher temperature enhanced hydrogen release kinetics leading to shortened induction period from 20 min at 95$^{\circ}C$ to 0 min at 130$^{\circ}C$. Melting and decomposition at close temperature (4$^{\circ}C$ difference) caused the formation of thin foam during hydrogen release. Suppression of by-products and thin foam formation during hydrogen release is suggested as critical issues to realize chemical hydrogen storage system with ammonia borane.

• 한국가스학회지
• /
• 제16권1호
• /
• pp.15-21
• /
• 2012

수소가스의 제트 누출에 의한 확산, 화재, 그리고 폭발에 의한 위험 범위를 분석하고, 안전거리 기준을 설정하기 위한 위험거리를 확산, 화재, 그리고 폭발에 대한 단순한 예측 식들을 제시하였다. 핀홀에 의한 누출과 같은 소량 수소가스 누출속도에 있어서 피해거리는 제트누출 확산에 의한 피해거리가 제트화재에 의한 피해거리보다 크며, 압력의 제곱근에 그리고 누출 홀의 직경에 비례하고 이는 수 십 미터에 이른다. 배관의 완전 파손 또는 저장 탱크의 큰 홀 발생과 같은 대량의 수소가스 누출속도에서는 제트화재의 피해거리가 개방공간의 가스운 폭발에 의한 피해거리보다 크며, 수 백 미터에 이른다. 수소충전소와 건물과의 최소이격거리 즉 안전거리 설정 기준을 대량 수소가스누출 사고시나리오를 기반으로 한다면, 도심지에 수소충전소는 안전거리 기준을 만족시키기 어려울 것이다. 따라서 대량의 수소가스 누출사고를 안전장치들을 통하여 예방하고, 안전거리 기준을 소량의 수소가스누출사고 기준으로 설정 할 수 있다. 그러나 대량누출 가능성이 있는 경우 학교와 병원 등 인구밀집 건물은 수 백 미터의 안전거리를 유지하여야 한다.

• Metals and materials international
• /
• 제24권6호
• /
• pp.1403-1411
• /
• 2018

Graphene (multilayer graphene) was chosen as an additive to improve the hydrogen uptake and release properties of magnesium (Mg). Five weight percent of graphene was added to pre-milled Mg by milling in hydrogen (reaction-involving milling). The hydrogen uptake and release properties of the graphene-added Mg were investigated. The activation of Mg-5graphene, which was prepared by adding 5 wt% graphene to Mg pre-milled for 24 h, was completed after the second cycle (cycle number, CN=2). Mg-5graphene had a high effective hydrogen-storage capacity (the quantity of hydrogen absorbed for 60 min) of 6.21 wt% at CN=3 at 593 K in 12 bar $H_2$. At CN=1, Mg-5graphene released 0.46 wt% hydrogen for 10 min and 4.99 wt% hydrogen for 60 min. Milling in hydrogen is believed to create defects (leading to facilitation of nucleation), produce cracks and clean surfaces (leading to increase in reactivity), and decrease particle size (leading to diminution of diffusion distances or increasing the flux of diffusing hydrogen atoms). The added graphene is believed to have helped the sample have higher hydrogen uptake and release rates, weakly but partly, by dispersing heat rapidly.

• 한국수소및신에너지학회논문집
• /
• 제34권6호
• /
• pp.712-721
• /
• 2023

While hydrogen is widely used, it has a low minimum ignition energy, raising safety concerns when using it. This research studied which parameters are the key variables in the hydrogen release and diffusion. These parameters were divided into six process variables in the initial release and two environmental variables in the dispersion. One hundred and twenty cases were selected through design of experiment, and the end-point in each case were analyzed using PHAST. Afterwards, an end-point prediction model was developed using RSM and ANOVA, and the impact of each variable on the endpoint was analyzed. As a result, the influence of eight variables was graded. The nozzle diameter had the greatest influence on the end-point, while the pipe roughness coefficient had no effect on the end-point. It is expected that these results will be used as basic data to improve safety across all fields of hydrogen handling facilities.

• 한국분말야금학회:학술대회논문집
• /
• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
• /
• pp.716-717
• /
• 2006

Gas release behavior from aluminum and Al 7075 alloy powders during heating in argon was investigated by in-situ gas chromatography. Water vapor, hydrogen, carbon mono-oxide were detected as individual evolution spectra against heating temperature and time. The mechanisms of water and hydrogen evolutions were studied in detail for the determination of effective degassing condition. Magnesium in the alloy powder was found to lower the hydrogen evolution temperature to enhance overall hydrogen release.

• 사상체질의학회지
• /
• 제11권2호
• /
• pp.251-266
• /
• 1999

1. 연구목적 본 실험은 청심연자탕이 대뇌신경세포의 산화적 손상에 대한 효능을 밝히기 위한 것이다. 2. 연구방법 신생 생쥐에서 분리 배양한 대뇌신경세포에 여러 농도의 hydrogen peroxide가 포함된 배양액에서 6시간 동안 처리하여 hydrogen peroxide가 배양 대뇌신경세포에 미치는 영향을 조사하였으며 hydrogen peroxide의 독성효과에 대한 청심연자당의 영향을 조사하였다. 3. 결과 및 결론 산소자유기인 hydrogen peroxide는 NR assay와 MTT assay에 의한 세포생존율을 감소시켰고 lipid peroxidation의 증가 및 LDH양의 증가에 의하여 생쥐의 배양 대뇌신경세포에 독성을 나타냈다. 청심연자탕(淸心蓮子湯)은 hydrogen peroxide의 산화적 손상에 대한 신경독성에 대하여 Iipid peroxidation의 감소에 유의한 효과를 보였다. 청심연자탕(淸心蓮子湯)은 hydrogen peroxide의 산화적 손상에 의한 신경독성에 대하여 LDH양의 감소에 유의한 효과를 보였다. 이상의 결과로 보아 hydrogen peroxide는 생쥐에서 분리한 대뇌신경세포에 산화적 손상에 의한 신경독성을 나타냈으며 청심연자탕(淸心蓮子湯)이 hydrogen peroxide와 같은 산소자유기의 산화적 손상에 대한 방어에 효과적인 것으로 사료된다.

• 한국가스학회지
• /
• 제26권3호
• /
• pp.21-26
• /
• 2022

아연은 인체에 유해한 카드뮴을 대체하여 금속재료에 수소가스가 침투하거나 금속재료 내부로부터 수소가 누출되는 것을 방지하기 위한 친환경 코팅 재료로 주목받고 있다. 일반적으로 수성 및 산성 분위기에서 수행되는 아연(Zn) 및 아연 합금의 전기도금은 낮은 쿨롱 효율, 부식 및 수소 누출과 같은 단점이 있어 산업적 이용이 어렵다. 본 연구에서는 염화콜린과 에틸렌글리콜을 이용하여 Deep-eutectic solvent를 합성하고 이를 용매로 사용하여 아연 도금용 전해질을 제조하여 STS 304 기판 위에 전기 도금하였다. 주사전자현미경(SEM)과 원자힘현미경(AFM)을 이용하여 표면 미세구조와 조도를 관찰하였다. X선회절분석(XRD)을 이용하여 도금 막의 결정구조를 분석하였다. 마지막으로 수소를 주입한 STS 304 기판에 최적화된 Zn 도금액을 코팅한 시료의 수소 방출 방지 효과를 분석하였다.

• 한국수소및신에너지학회논문집
• /
• 제19권3호
• /
• pp.189-198
• /
• 2008

Cooperative effects of Rh, Ce and Zr added to Fe-based oxide mediums were investigated using temperature programmed redox reaction (TPR/TPO) and isothermal redox reaction in the view point of hydrogen storage and release. As the results of TPR/TPO, Rh was a sale additive to remarkably promote the redox reaction on the medium as evidenced by the lower highest peak temperature, even though its addition was to accelerate deactivation of the mediums due to sintering. On the other hand, Ce and Zr additives played an important role to suppress deactivation of the medium in repeated redox cycles. The medium co-added by Rh, Ce and Zr (FRCZ) exhibited synergistic performance in the repeated isothermal redox reaction, and the amount of hydrogen produced in the water splitting step at 623 K was highly maintained at ca. $17\;mmol{\cdot}g^{-1}-Fe$ during three repeated redox cycles.

• 한국자동차공학회논문집
• /
• 제15권5호
• /
• pp.24-29
• /
• 2007

This study aims to provide a fundamental data for directly injected hydrogen fuel engines. Spray, ignition and combustion characteristics of hydrogen were studied using constant volume chamber. For spray visualization, hydrogen was vertically injected into a combustion chamber at various condition, for example, injection pressure, ambient pressure. And an argon laser was used for the shadowgraph photography by applying optical method. Also, to investigate heat-release rate and flame propagations, spark was ignited on hydrogen injected at the different time after injection and the duration of injection was also changed. Processes of ignition and combustion were analyzed by heat-release rate calculated by pressure history and were observed by shadowgraph photography The results gave much knowledge of spray, ignition and combustion characteristics of hydrogen.

• 한국수소및신에너지학회논문집
• /
• 제19권3호
• /
• pp.239-247
• /
• 2008

Hydrogen production facility using very high temperature gas cooled reactor lies in situation of high temperature and corrosion which makes hydrogen release easily. In that case of hydrogen release, there lies a danger of explosion. However, from the point of thermal-hydraulics view, the long distance of them makes lower efficiency result. In this study, therefore, outlines of hydrogen production using nuclear energy are researched. Several methods for analyzing the effects of hydrogen explosion upon high temperature gas cooled reactor are reviewed. Reliability physics model which is appropriate for assessment is used. Using this model, leakage probability, rupture probability and structure failure probability of very high temperature gas cooled reactor are evaluated and classified by detonation volume and distance. Also based on standard safety criteria which is value of $1{\times}10^{-6}$, safety distance between the very high temperature gas cooled reactor and the hydrogen production facility is calculated.