• Title, Summary, Keyword: Hydrogen

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A Study on Explosive Hazardous Areas in Hydrogen Handling Facility (수소 취급설비의 폭발위험장소에 관한 연구)

  • PYO, DON-YOUNG;LIM, OCK-TAECK
    • Transactions of the Korean hydrogen and new energy society
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    • v.30 no.1
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    • pp.29-34
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    • 2019
  • Safety of hydrogen handling facilities is needed as supply of hydrogen cars has been expanded recently. In this study, the adequacy of safety regulations of hydrogen handling facilities and the risk of damage with hydrogen leakage were studied. The range of explosion hazard location of the hydrogen filling plant was investigated using the computational fluid dynamics (CFD) method, Explosive hazardous area is influenced by leakage type, hole size and sectional area. When the conditions of KS standard are applied, range explosive hazardous area is expanded 7.05 m, maximum. It is about 7 times larger than exceptional standard of hydrogen station. Meanwhile, distance from leakage point to 25% LEL of hydrogen is investigated 1.6 m. Considering the shape of charging hose, regulation of hydrogen station is appropriate.

Surface adsorption and bulk diffusion of hydrogen atoms on ZnO surfaces

  • Roy, Probir Chandra;Doh, Won-Hui;Kim, Chang-Min
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.76-76
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    • 2010
  • The interaction of hydrogen (H) and ZnO surfaces has been investigated using a temperature programmed desorption (TPD) technique. When the surface is exposed to atomic hydrogen below 400 K, hydrogen is adsorbed on the surface. As the hydrogen exposure increases, bulk diffusion of hydrogen takes place. The existence of surface and bulk hydrogen has been confirmed using X-ray photoelectron spectroscopy (XPS). When the ZnO(000-1) surface dosed with hydrogen is heated, surface hydrogen is desorbed at 432 K and bulk hydrogen is evolved at ~539 K. Diffusion of hydrogen into the ZnO bulk is an activated process, and the activation energy is estimated to be 0.19 eV. Diffusion of hydrogen on the ZnO(10-10) surface is also investigated.

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An Investigation on the Proper Hydrogen Mixing Rate in Heavy-Duty Hydrogen-CNG Engine (수소-천연가스 혼합연료기관의 최적 수소 분사율 검토)

  • LlM, H.S.;KIM, Y.Y.;LEE, JONG T.
    • Transactions of the Korean hydrogen and new energy society
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    • v.15 no.2
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    • pp.89-97
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    • 2004
  • A heavy duty hydrogen enriched CNG engine has the possibility to obtain stable operation at ultra lean condition and to reduce emission extremely. And it can also serve as a so called bridge technology between the current fossil fueled engine and the future hydrogen power system. The emission, torque and brake thermal efficiency characteristics of a heavy-duty hydrogen-CNG engine were investigated to determine the proper mixing rate of hydrogen and CNG. It was found that the proper mixing rates at ${\lambda}=1.4$ and ${\lambda}=1.6$ were around 20% and 30% for hydrogen addition rate respectively.

A Study on the Explosion Characteristics of Hydrogen (수소의 폭발 특성에 관한 연구)

  • Oh, Kyu-hyung;Rhie, Kwang-won
    • Transactions of the Korean hydrogen and new energy society
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    • v.15 no.3
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    • pp.228-234
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    • 2004
  • It was discussed about explosion danger of hydrogen gas experimentally that could be happen during the handling and using. Hydrogen concentration was varied from 10 to 60 vol% for get the explosion characteristics of hydrogen and 5 kinds of cylindrical vessel were used to find the explosion characteristics of hydrogen according to the vessel volume. Initial pressure of hydrogen-air mixture was varied from 0.6 to 2 kg/cm2. Based on the experiment, explosion pressure was most high near the 30vol% of hydrogen and explosion pressure was increased slightly according to the increase of vessel volume but explosion pressure rise rate was decreased. Explosion pressure was increased linearly proportional to the initial pressure of gas mixture.

Effects of Temperature on Production of Hydrogen in Anaerobic Fermentation (혐기성 발효에서 수소 생산 시 온도의 영향에 관한 연구)

  • Kim, Choong-Gon;Kang, Seon-Hong
    • Journal of Korean Society of Water and Wastewater
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    • v.21 no.4
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    • pp.467-475
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    • 2007
  • This study was conducted to examine temperature effects on hydrogen production in anaerobic fermentation. 18 batch reactors were operated at mesophilic ($35^{\circ}C$) and thermophilic conditions ($55^{\circ}C$) to achieve maximum hydrogen production in anaerobic fermentation. Optimum hydrogen production conditions were also investigated at each temperature. Different trends were observed regarding pH effects on hydrogen production. This effect was not significant for mesophilic fermentation ($35^{\circ}C$). In this case, pH may not drop to interfere hydrogen production during the test. However, hydrogen production decreased without pH control for thermophilic condition ($55^{\circ}C$). Effects of heat treatment were observed for both fermentation process. Hydrogen production with heat treatment was higher than hydrogen production without heat treatment for both fermentation processes. The amount of produced hydrogen for each substrate concentration with temperature changes showed that more hydrogen was produced at $35^{\circ}C$ than at $55^{\circ}C$.

Experimental and Numerical Study on the Hydrogen Refueling Process (고압 수소 충전 시스템에 대한 실험 및 수치해석)

  • Lee, Taeck-Hong;Kim, Myoung-Jin;Park, Jong-Kee
    • Transactions of the Korean hydrogen and new energy society
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    • v.18 no.3
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    • pp.342-347
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    • 2007
  • The research on production and application of hydrogen as an alternative energy in the future is being carried out actively. It hydrogen storage is necessary in order that user use hydrogen economically without much difficulty. Among the ways of hydrogen storage the method which is compressed hydrogen gas by high pressure is easier for application than other methods. In this study, we have been calculated gas with changing pressure and temperature variation of container wall through applied to mass and energy balance equation when compressing hydrogen by high pressure, and also to Beattie-Bridgeman equation of state for the kinetic of hydrogen. We will apply above date as a preliminary for design of hydrogen storage tank.

A Study on Safety Policies for a Transition to a Hydrogen Economy (수소경제로의 이행을 위한 안전관리 정책 연구)

  • Jun, Daechun
    • Transactions of the Korean hydrogen and new energy society
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    • v.25 no.2
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    • pp.161-172
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    • 2014
  • Hydrogen, which can be produced from abundant and widely distributed renewable energy resources, seems to be a promising candidate for solving the concerns for improving energy security, urban air pollution, and reducing greenhouse gas emissions. The two primary motivating factors for hydrogen economy are fossil fuel supply limitations and concerns about global warming. But the safety issues associated with hydrogen economy need to be investigated and fully understood before being considered as a future energy source. Limited operating experience with hydrogen energy systems in consumer environments is recognised as a significant barrier to the implementation of hydrogen economy. To prevent unnecessary restrictions on emerging codes, standards and local regulations, safety policies based on real hazards should be developed. This article studies briefly the direct impact-distances from hazard events such as hydrogen release and jet fire, and damage levels from hydrogen gas explosion in a confined space. Based on the direct impact-distances indicated in the accident scenarios and consumer environments in Korea, the safety policies, which are related to hydrogen filling station, hydrogen fuel cell car, portable fuel cell, domestic fuel cells, and hydrogen town, are suggested to implement hydrogen economy. To apply the safety policies and overcome the disadvantages of prescriptive risk management, which is setting guidance in great detail to management well known risk but is not covering unidentified risk, hybrid risk management model is also proposed.

Flexible Hydrogen Sensor Using Ni-Zr Alloy Thin Film

  • Yun, Deok-Whan;Park, Sung Bum;Park, Yong-il
    • Korean Journal of Materials Research
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    • v.29 no.5
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    • pp.297-303
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    • 2019
  • A triple-layered $PMMA/Ni_{64}Zr_{36}/PDMS$ hydrogen gas sensor using hydrogen permeable alloy and flexible polymer layers is fabricated through spin coating and DC-magnetron sputtering. PDMS(polydimethylsiloxane) is used as a flexible substrate and PMMA(polymethylmethacrylate) thin film is deposited onto the $Ni_{64}Zr_{36}$ alloy layer to give a high hydrogen-selectivity to the sensor. The measured hydrogen sensing ability and response time of the fabricated sensor at high hydrogen concentration of 99.9 % show a 20 % change in electrical resistance, which is superior to conventional Pd-based hydrogen sensors, which are difficult to use in high hydrogen concentration environments. At a hydrogen concentration of 5 %, the resistance of electricity is about 1.4 %, which is an electrical resistance similar to that of the $Pd_{77}Ag_{23}$ sensor. Despite using low cost $Ni_{64}Zr_{36}$ alloy as the main sensing element, performance similar to that of existing Pd sensors is obtained in a highly concentrated hydrogen atmosphere. By improving the sensitivity of the hydrogen detection through optimization including of the thickness of each layer and the composition of Ni-Zr alloy thin film, the proposed Ni-Zr-based hydrogen sensor can replace Pd-based hydrogen sensors.

Hydrogen Diffusion in APX X65 Grade Linepipe Steels

  • Park, Gyu Tae;Koh, Seong Ung;Kim, Kyoo Young;Jung, Hwan Gyo
    • Corrosion Science and Technology
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    • v.5 no.4
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    • pp.117-122
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    • 2006
  • Hydrogen permeation measurements have been carried out on API X65 grade linepipe steel. In order to study the effect of steel microstructure on hydrogen diffusion behavior in linepipe steel, the accelerated cooling condition was applied and then three different kinds of microstructures were obtained. Hydrogen permeation measurement has been performed in reference to modified ISO17081 (2004) and ZIS Z3113 method. Hydrogen trapping parameters in these steels were evaluated in terms of the effective diffusivity ($D_{eff}$), permeability ($J_{ss}L$) and the amount of diffusible hydrogen. In this study, microstructures which affect both hydrogen trapping and diffusion were degenerated pearlite (DP), acicular ferrite (AF), bainite and martensite/austenite constituents (MA). The low $D_{eff}$ and $J_{ss}L$ mean that more hydrogen can be trapped reversibly or irreversibly and the corresponding steel microstructure is dominant hydrogen trapping site. The large amount of diffusible hydrogen means that corresponding steel microstructure is predominantly reversible. The results of this study suggest that the hydrogen trapping efficiency increases in the order of DP, bainite and AF, while AF is the most efficient reversible trap.

An Overview on Hydrogen Uptake, Diffusion and Transport Behavior of Ferritic Steel, and Its Susceptibility to Hydrogen Degradation

  • Kim, Sung Jin;Kim, Kyoo Young
    • Corrosion Science and Technology
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    • v.16 no.4
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    • pp.209-225
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    • 2017
  • Development of high strength steel requires proper understanding of hydrogen behavior since the higher the steel strength the greater the susceptibility of hydrogen assisted cracking. This paper provides a brief but broad overview on hydrogen entry and transport behavior of high-strength ferritic steels. First of all, hydrogen absorption, diffusion and trapping mechanism of the steels are briefly introduced. Secondly, several experimental methods for analyzing the physical/chemical nature of hydrogen uptake and transport in the steels are reviewed. Among the methods, electrochemical permeation technique utilized widely for evaluating the hydrogen diffusion and trapping behavior in metals and alloys is mainly discussed. Moreover, a modified permeation technique accommodating the externally applied load and its application to a variety of steels are intensively explored. Indeed, successful utilization of the modified permeation technique equipped with a constant load testing device leads to significant academic progress on the hydrogen assisted cracking (HAC) phenomenon of the steels. In order to show how the external and/or residual stress affects mechanical instability of steel due to hydrogen ingress, the relationship among the microstructure, hydrogen permeation, and HAC susceptibility is briefly introduced.