• Title/Summary/Keyword: Hydrogen

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The Hydrogenation Behaviors of V-xAl (x=1, 5wt.%) Composites by Mechanical Alloying (기계적 합금화법으로 제조한 V-xAl (x=1, 5wt.%) 복합재료의 수소화 반응 거동)

  • Kim, Kyeong-Il;Hong, Tae-Whan
    • Transactions of the Korean hydrogen and new energy society
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    • v.22 no.4
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    • pp.458-464
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    • 2011
  • Recently, one of the hydrogen production methods has attracted using dense metallic membrane. It has high hydrogen permeation and selectivity which hardly could adopt industrial product because of high cost, hydrogen embrittlment and thermal stability. Meanwhile, vanadium has high hydrogen solubility and it use to instead of Pd-Ag amorphous membrane. Aluminum carried out blocking hydrogen diffusion on grain boundary therefore protecting hydrogen embrittlement. Most of dense metallic membrane is solution diffusion mechanism. The solution diffusion mechanism was very similar hydrogen storing steps such as steps of metal hydride. Thus, V-Al composites were fabricated to use hydrogen induced mechanical alloying. The fabricated V-Al composites were characterized by XRD, SEM, EDS and simultaneous TG/DSC analyses. The hydrogenation behaviors were evaluated using a Sievert's type automatic PCT apparatus. The hydrogenation behaviors of V-Al composites was evaluated too low hydrogen stored capacity and fast hydrogenation kinetics. In PCI results, V-Al composites had low hydrogen solubility, in spite of that, hydrogen kinetics was calculated very fast and hydrogen absorption/desorption contents were same capacity.

Economic Evaluation of Domestic Low-Temperature Water Electrolysis Hydrogen Production (국내 저온수전해 수소생산의 경제성 평가)

  • Gim, Bong-Jin;Kim, Jong-Wook;Ko, Hyun-Min
    • Transactions of the Korean hydrogen and new energy society
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    • v.22 no.4
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    • pp.559-567
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    • 2011
  • This paper deals with an economic evaluation of domestic low-temperature water electrolysis hydrogen production. We evaluate the economic feasibility of on-site hydrogen fueling stations with the hydrogen production capacity of 30 $Nm^3/hr$ by the alkaline and the polymer electrolyte membrane water electrolysis. The hydrogen production prices of the alkaline water electrolysis, the polymer electrolyte membrane water electrolysis, and the steam methane reforming hydrogen fueling stations with the hydrogen production capacity of 30 $Nm^3/hr$ were estimated as 18,403 $won/kgH_2$, 22,945 $won/kgH_2$, 21,412 $won/kgH_2$, respectively. Domestic alkaline water electrolysis hydrogen production is evaluated as economical for small on-site hydrogen fueling stations, and we need to further study the economic evaluation of low-temperature water electrolysis hydrogen production for medium and large scale on-site hydrogen fueling stations.

Analysis of Hydrogen Production Cost by Production Method for Comparing with Economics of Nuclear Hydrogen (원자력 수소 경제성 비교를 위한 수소 생산 방법별 생산단가 분석)

  • Lim, Mee-Sook;Bang, Jin-Hwan;Yoon, Young-Seek
    • Transactions of the Korean hydrogen and new energy society
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    • v.17 no.2
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    • pp.218-226
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    • 2006
  • It can be obtained from hydrocarbon and water, specially production of hydrogen from natural gas is most commercial and economical process among the hydrogen production methods, and has been used widely. However, conventional hydrogen production methods are dependent on fossil fuel such as natural gas and coal, and it may be faced with problems such as exhaustion of fossil fuels, production of greenhouse gas and increase of feedstock price. Thermochemical hydrogen production by nuclear energy has potential to efficiently produce large quantities of hydrogen without producing greenhouse gases. However, nuclear hydrogen must be economical comparing with conventional hydrogen production method. Therefore, hydrogen production cost was analyzed and estimated for nuclear hydrogen as well as conventional hydrogen production such as natural gas reforming and coal gasification in various range.

Hydrogen Embrittlement Characteristics by Slow Strain Rate Test of Aluminum Alloy for Hydrogen Valve of Hydrogen Fuel Cell Vehicle (수소연료전지 자동차의 수소밸브용 알루미늄 합금의 저변형율인장실험에 의한 수소취화특성 연구)

  • Hyun-Kyu, Hwang;Dong-Ho, Shin;Seong-Jong, Kim
    • Corrosion Science and Technology
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    • v.21 no.6
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    • pp.503-513
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    • 2022
  • As part of eco-friendly policies, interest in hydrogen vehicles is growing in the automotive industry to reduce carbon emissions. In particular, it is necessary to investigate the application of aluminum alloy for light weight hydrogen valves among hydrogen supply systems to improve the fuel efficiency of hydrogen vehicles. In this research, we investigated mechanical characteristics of aluminum alloys after hydrogen embrittlement considering the operating environment of hydrogen valves. In this investigation, experiments were conducted with strain rate, applied voltage, and hydrogen embrittlement time as variables that could affect hydrogen embrittlement. As a result, a brittle behavior was depicted when the strain rate was increased. A strain rate of 0.05 mm/min was selected for hydrogen embrittlement research because it had the greatest effect on fracture time. In addition, when the applied voltage and hydrogen embrittlement time were 5 V and 96 hours, respectively, mechanical characteristics presented dramatic decreases due to hydrogen embrittlement.

Estimation of Hydrogen Filling Time Using a Dynamic Modeling (동적 모델링에 의한 수소 충전 시에 걸리는 시간의 산출)

  • NOH, SANGGYUN
    • Transactions of the Korean hydrogen and new energy society
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    • v.32 no.3
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    • pp.189-195
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    • 2021
  • A compressed hydrogen tank is to be repressurized to 40 bar by being connected to a high-pressure line containing hydrogen at 50 bar and 25℃. Hydrogen filling time and the corresponding hydrogen temperature has been estimated when the filling process stopped according to several thermodynamic models. During the process of cooling the hydrogen tank, hydrogen temperature and pressure vs. time estimation was performed using Aspen Dynamics. Filling time, hydrogen temperature after filling hydrogen gas, cooling time and the final tank pressure after tank filling process have been completed according to the thermodynamic models are almost same.

The Evaluation of Hydrogen Leakage Safety for the High Pressure Hydrogen System of Fuel Cell Vehicle (연료전지자동차의 고압수소저장시스템 수소 누출 안전성 평가)

  • Kim, Hyun-Ki;Choi, Young-Min;Kim, Sang-Hyun;Shim, Ji-Hyun;Hwang, In-Chul
    • Transactions of the Korean hydrogen and new energy society
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    • v.23 no.4
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    • pp.316-322
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    • 2012
  • A fuel cell vehicle has the hydrogen detection sensors for checking the hydrogen leakage because it use hydrogen for its fuel and can't use a odorant to protect the fuel cell stack. To verify the hydrogen safety of leakage we select the high possible leak points of fittings in hydrogen storage system and test the leaking behavior at them. The hydrogen leakage flow rate is 10, 40, 118 NL/min and the criterion for maximum hydrogen leakage is based on allowing an equivalent release of combustion energy as permitted by gasoline vehicles in FMVSS301. There are total 18EA hydrogen leakage detection sensors installed in test system. we acquire the hydrogen leakage detection time and determine the ranking. Hydrogen leakage detection time decrease when hydrogen leakage flow rate increase. The minimum hydrogen leakage detection time is about 3 seconds when the flow rate is 118NL/min. In this study, we optimize hydrogen sensor position in fuel cell vehicle and verify the hydrogen leakage safety because there is no inflow inside the vehicle.

Analysis of Costs for a Hydrogen Refueling Station in Korea (한국 수소 충전소 건설의 경제성 분석)

  • KANG, BYOUNGWOO;KIM, TAEHYUN;LEE, TAECKHONG
    • Transactions of the Korean hydrogen and new energy society
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    • v.27 no.3
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    • pp.256-263
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    • 2016
  • As the hydrogen era comes near future, hydrogen fuel cell vehicles are core of hydrogen economy. Until now, Korea has 17 hydrogen refueling stations but 9 hydrogen refueling stations have been retired already and 8 hydrogen refueling stations are still running. With a limited number of hydrogen refueling stations, it is very difficult to get scientific data for the economy of hydrogen refueling stations in Korea. Thus, based on NREL(National Renewable Energy Laboratory) study, we analyzed most recent data for the construction of hydrogen refueling stations in one specific site in Korea. The cost comparison data between Korea and USA shows 14% difference, saying higher costs of Korea. Korea looks 5 years delay compared to USA. This data will be an important tool for the investment from every industrial parties.

The Finite Element Analysis on the Characteristics of the Hydrogen Diffusion for the Cr-Mo Steels (Cr-Mo강의 수소확산 특성에 관한 유한요소해석)

  • Lee, Hwi-Won;Ha, Min-Su
    • Journal of the Korean Society of Mechanical Technology
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    • v.13 no.2
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    • pp.115-121
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    • 2011
  • The size of hydrogen molecule is not so small as to invade into the lattice of material, and therefore, hydrogen invades into the material as atom. Hydrogen movement is done by diffusion or dislocation movement in the near crack tip or plastic deformation. Hydrogen appeared to have many effects on the mechanical properties of the Cr-Mo steel alloys. The materials for this study are 1.25Cr-0.5Mo and 2.25Cr-1Mo steels used at high temperature and pressure. The hydrogen amount obtained by theoretical calculation was almost same with the result solved by finite element analysis. The distribution of hydrogen concentration and average concentration was calculated for a flat specimen. Also, finite element analysis was employed to simulate the redistribution of hydrogen due to stress gradient. The calculation of hydrogen concentration diffused into the material by finite element method will provide the basis for the prediction of delayed fracture of notched specimen. The distribution of hydrogen concentration invaded into the smooth and notched specimen was obtained by finite element analysis. The hydrogen amount is much in smooth specimen and tends to concentrate in the vicinity of surface. Hydrogen embrittlement susceptibility of notched specimen after hydrogen charging is more remarkable than that of smooth specimen.

Development of an Mg-Based Alloy with a Hydrogen-Storage Capacity over 6 wt% by Adding Graphene

  • Choi, Eunho;Kwak, Young Jun;Song, Myoung Youp
    • Metals and materials international
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    • v.24 no.6
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    • pp.1403-1411
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    • 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.

Analysis of the Economy of Scale for Domestic Steam Methane Reforming Hydrogen Refueling Stations Utilizing the Scale Factor (Scale Factor를 이용한 국내 천연가스 개질식 수소충전소의 규모의 경제 분석)

  • GIM, BONGJIN;YOON, WANG LAI;SEO, DONG JOO
    • Transactions of the Korean hydrogen and new energy society
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    • v.30 no.3
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    • pp.251-259
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    • 2019
  • The aim of this study is to evaluate the economic feasibility of domestic on-site steam methane reforming (SMR) hydrogen refueling stations. We evaluated the levelized cost of hydrogen (LCOH) for the SMR hydrogen refueling stations, which have production capacities of 100 kg/day (SMR 100), 200 kg/day (SMR 200), and 500 kg/day (SMR 500) utilizing the scale factor. The main results indicated that the LCOH of SMR 100, SMR 200, and SMR 500 were 14,367 won/kg, 11,122 won/kg, and 8,157 won/kg, if the utilizations of hydrogen stations were 70%. These results imply that the production capacity of the domestic SMR hydrogen station should be greater than 500 kg/day to compete with other hydrogen stations when we consider the current sale price of hydrogen at the hydrogen stations.