Hydrogen Storage and Release Properties of Transition Metal-Added Magnesium Hydride Alloy Fabricated by Grinding in a Hydrogen Atmosphere

( Sung Nam Kwon ),( Hye Ryoung Park ),( Myoung Youp Song ) 대한금속재료학회(구 대한금속학회) 2016 대한금속·재료학회지 Vol.54 No.7

90 wt% MgH2+5 wt% Ni+2.5 wt% Fe+2.5 wt% Ti (called MgH2+Ni+Fe+Ti), a hydrogen storage and release material, was fabricated by grinding in a hydrogen atmosphere, and then its quantities of stored and released hydrogen as a function of time were examined. A nanocrystalline MgH2+Ni+Fe+Ti specimen was made by grinding in a hydrogen atmosphere and subsequent hydrogen storage-release cycling. The crystallite size of Mg and the strain of the Mg crystallite after ten hydrogen storage-release cycles, which were obtained using the Williamson-Hall method, were 38.6 (±1.4) nm and 0.025 (±0.0081) %, respectively. The MgH2+Ni+Fe+Ti sample after the process of grinding in a hydrogen atmosphere was highly reactive with hydrogen. The sample exhibited an available storage capacity of hydrogen (the amount of hydrogen stored during 60 minutes) of about 5.7 wt%. At the first cycle, the MgH2+Ni+Fe+Ti sample stored hydrogen of 5.53 wt% in 5 minutes, 5.66 wt% in 10 minutes and 5.73 wt% in 60 minutes at 573 K and 12 bar of hydrogen. The MgH2+Ni+Fe+Ti after activation released hydrogen of 0.56 wt% in 5 minutes, 1.26 wt% in 10 minutes, 2.64 wt% in 20 minutes, 3.82 wt% in 30 minutes, and 5.03 wt% in 60 minutes. †(Received November 6, 2015; Accepted February 13, 2016)

베이나이트계 X70강 수소가압분위기 인장시험의 수소취성균열 전파

최병학,장현수,이범규,김의수,김우식,백운봉,남승훈 대한금속·재료학회 2018 대한금속·재료학회지 Vol.56 No.1

This study investigated hydrogen induced cracking (HIC) of X70 steel, used for gas pipeline material, with a bainitic microstructure. The effect of hydrogen on the steel was investigated by tensiletesting in a high pressure hydrogen atmosphere, using OM, SEM and TEM analyses. The mechanisms of hydrogen-related cracking were represented as stress-induced hydride formation, hydrogen enhanced localized plasticity and decohesion. While hydrogen-trapped sites increased the HIC susceptibility, a kind of surface corrosion occurred in the tensile tested gauge length, due to the high pressured hydrogen atmosphere. The surface corrosion was composed of HIV (hydrogen induced voids) and HIC occurred by linking of the voids. Typical SOHIC (stress oriented HIC) propagated to the inner areas by linking of planar cracks normal to the primary propagation direction. Carbides at grain and lath boundary of the X70 bainite acted as initiation sites of the voids, followed by cracking without any phase transformation. The relation of hydrogen induced defects and grain boundary carbide is discussed in relation to hydrogen corrosion and safe application in hydrogen system.

수소 전주기 경제성 분석 프로그램 개발

김수현,유영돈,박혜민 한국수소및신에너지학회 2022 한국수소 및 신에너지학회논문집 Vol.33 No.6

In this study, economic analysis program was developed for economic evaluation of hydrogen production, storage/delivery, and utilization technologies as well as overseas import of hydrogen. Economic analysis program can be used for the estimation of the levelized cost of hydrogen for hydrogen supply chain technologies. This program include five hydrogen production technology on steam methane reforming and water electrolysis, two hydrogen storage technologies (high compressed gas and liquid hydrogen storage), three hydrogen delivery technologies (compressed gas delivery using tube trailer, liquid hydrogen, and pipeline transportation) and six hydrogen utilization technologies on hydrogen refueling station and stationary fuel cell system. In the case of overseas import hydrogen, it was considered to be imported from five countries (Austraila, Chile, India, Morocco, and UAE), and the transportation methods was based on liquid hydrogen, ammonia, and liquid organic hydrogen carrier. Economic analysis program that was developed in this study can be expected to utilize for planning a detailed implementation methods and hydrogen supply strategies for the hydrogen economy road map of government.

Review of Hydrogen Gas Sensors for Future Hydrogen Mobility Infrastructure

Jun-Seo Lee,안진우,배수강,이승기 한국진공학회 2022 Applied Science and Convergence Technology Vol.31 No.4

The indiscriminate use of fossil fuels has adverse effects, such as environmental pollution and climate change. Therefore, there is growing interest in using hydrogen as an eco-friendly energy source. Among the diverse applications of hydrogen energy, hydrogen mobility has attracted considerable attention because it can compensate for the limitations of existing internal combustion engines and electricity-based mobility. To this end, relevant hydrogen-based infrastructure is being built in urban areas with rapid technological advancements. However, recent explosions of hydrogen charging stations in Norway and hydrogen storage tanks in South Korea have led to anxiety and the rejection of hydrogen application infrastructure. Therefore, to ensure the stability and safe operation of newly built infrastructure for hydrogen mobility in urban areas, an advanced system is required to improve existing technologies for hydrogen safety management. A hydrogen sensor is a front-line device for identifying initial hydrogen leaks and monitoring the status of hydrogen; thus, it is a building block for safety management systems. In this review, the operating principles and state-of-the-art hydrogen sensors are described by focusing on their suitability in hydrogen mobility applications based on the possibility of miniaturization and high hydrogen selectivity.

Hydrogen Sorption of Pure Mg and Niobium (V) Fluoride-Added Mg Alloys Prepared by Planetary Ball Milling in Hydrogen

( Hye Ryoung Park ),( Young Jun Kwak ),( Seong Ho Lee ),( Myoung Youp Song ) 대한금속재료학회(구 대한금속학회) 2016 대한금속·재료학회지 Vol.54 No.12

In this work, niobium (V) fluoride was selected as an additive to heighten the hydrogen sorption rates of Mg. Specimens of pure Mg, 5 wt% niobium fluoride-added Mg, and 10 wt% niobium fluorideadded Mg were prepared by planetary ball milling in hydrogen. The hydrogen sorption properties of the specimens were then examined. An Mg-based hydrogen-storage alloy with an effective hydrogenstorage capacity of about 5.5 wt% was developed. At 593 K in 12 bar hydrogen at the first cycle (Cn = 1), the 5 wt% niobium fluoride-added Mg stored 4.37 wt% hydrogen in 5 min and 5.50 wt% hydrogen in 30 min. At 593 K in 1.0 bar hydrogen at Cn = 1, the 5 wt% niobium fluoride-added Mg released 2.11 wt% hydrogen in 10 min, 4.66 wt% hydrogen in 30 min, and 5.43 wt% hydrogen in 60 min. The planetary ball milling of Mg with NbF5 in hydrogen, which generated MgF2, NbH2, and NbF3, is believed to have produced imperfections both on the surface and in the interior of the Mg particles, created clean surfaces, and diminished the particle size of the Mg. The 5 wt% niobium fluoride-added Mg specimen stored a larger quantity of hydrogen in 30 min and a larger quantity of hydrogen was released in 60 min compared with the 10 wt% niobium fluoride-added Mg, or the pure Mg. †(Received April 5, 2016; Accepted June 27, 2016)

Materials for hydrogen supply infrastructure and its welding

김영식,조상명 대한용접·접합학회 2021 대한용접학회 특별강연 및 학술발표대회 개요집 Vol.2021 No.11

The effort for realizing the society based on hydrogen with the carbon neutral is prevailing all over the world. Over the past years, hydrogen has been identified as the most promising carrier of clean energy replacing the fossil fuels to mitigate greenhouse emissions. Hydrogen is the main working medium in fuel cells and hydrogen-based energy storage systems, integrating with other renewable energy systems is becoming very feasible. Hydrogen can be stored either as a compressed gas, a refrigerated liquefied gas, a cryo- compressed gas or a systems based on chemical absorption and metal hydrides, It was also found that several chemical hydrogen storage technologies, specifically methanol, ammonia, and other liquid organic hydrogen carriers(LOHCs), could possibly outmatch hydrogen liquefaction in terms of the electricity demand of the total storage process, While it is obvious that novel storage technologies, all but the storage of liquid or compressed gaseous hydrogen, are still at relatively early stages of development, it is also evident that some of these technologies are encouraging from the perspective of density of storage. It is indeed essential for the development of applications requiring long-term performance to have good understanding of long-term behaviour of the materials of the storage device and its components under operational loads. Most metallic alloys suffer a significant deterioration in mechanical properties when service in high pressure hydrogen environments, such as a marked increase in the fatigue-crack propagation and the susceptibility to hydrogen embrittlement. Austenitic stainless steel (AUSS) is a good candidate for using in this circumstances because it has low susceptibility to hydrogen environment embrittlement(HEE). However, it is notable that the δ ferrite produced in welding process of the AUSS can be raised susceptibility to HEE. The other materials such as aluminum alloy, high manganese steel and CFRP are used in manufacturing of the storage vessels of the compressed or liquid hydrogen gas which is used in vehicles, This lecture gives an overview of hydrogen storage technologies and details the specific issues related to the materials behaviour in hydrogen and conditions representative of hydrogen energy uses.

Development of a Hydrogen Uptake-Release Mg-Based Alloy by Adding a Polymer CMC (Carboxymethylcellulose, Sodium Salt) via Reaction-Accompanying Milling

Young Jun Kwak,Eunho Choi,Myoung Youp Song 대한금속·재료학회 2018 METALS AND MATERIALS International Vol.24 No.5

The addition of carboxymethylcellulose, sodium salt (CMC) might improve the hydrogen uptake and release properties ofMg since it has a relatively low melting point and the melting of CMC during milling in hydrogen (reaction-accompanyingmilling) may make the milled samples be in good states to absorb and release hydrogen rapidly and to have a large hydrogenstoragecapacity. Samples with compositions of 95 w/o Mg + 5 w/o CMC (named Mg–5CMC) and 90 w/o Mg + 10 w/o CMC(named Mg–10CMC) were prepared by adding CMC via reaction-accompanying milling. Activation of Mg–10CMC wascompleted after about 3 hydrogen uptake-release cycles. Mg–10CMC had a higher initial hydrogen uptake rate and a largeramount of hydrogen absorbed in 60 min, U (60 min), than Mg–5CMC before and after activation. At the cycle number ofthree (CN = 3), Mg–10CMC had a very high initial hydrogen uptake rate (1.56 w/o H/min) and a large U (60 min) (5.57 w/oH) at 593 K in hydrogen of 12 bar, showing that the activated Mg–10CMC has an effective hydrogen-storage capacity ofabout 5.6 w/o at 593 K in hydrogen of 12 bar at CN = 3. At CN = 2, Mg–10CMC released 1.00 w/o H in 2.5 min, 4.67 w/oH in 10 min, and 4.76 w/o H in 60 min at 648 K in hydrogen of 1.0 bar. The milling in hydrogen of Mg with CMC is believedto generate imperfections and cracks and reduce the particle size. The addition of 10 w/o CMC was more effective on theinitial hydrogen uptake rate and U (60 min) compared with the 10 w/o additions of NbF 5 , TaF 5 , Fe 2 O 3 , and MnO, and the10 w/o simultaneous addition of Ni, Fe, and Ti. To the best of our knowledge, this study is the fi rst in which a polymer CMCis added to Mg by reaction-accompanying milling to improve the hydrogen storage properties of Mg.

Enhancement of photocatalytic hydrogen production by liquid phase plasma irradiation on metal-loaded TiO₂/carbon nanofiber photocatalysts

Chung, Kyong-Hwan,Jeong, Sangmin,Kim, Byung-Joo,An, Kay-Hyeok,Park, Young-Kwon,Jung, Sang-Chul Elsevier 2018 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.43 No.24

<P><B>Abstract</B></P> <P>Enhanced hydrogen production by photocatalytic decomposition was assessed using liquid phase plasma over metal-loaded photocatalysts. Effects of irradiation of the liquid phase plasma were evaluated in the photocatalytic hydrogen production of hydrogen. Carbon nanofiber was introduced as photocatalytic support for the Ni-loaded TiO<SUB>2</SUB> photocatalyst. The influence of addition of organic reagents into water on hydrogen evolution was also evaluated. The photocatalytic decomposition by irradiation of the liquid phase plasma without photocatalyst produced some hydrogen evolution. The rate of hydrogen evolution was improved by the metal loading on the TiO<SUB>2</SUB> surface. The carbon nanofiber acted as a useful photocatalytic support for the fixation of TiO<SUB>2</SUB>. Hydrogen evolution was enhanced by the Ni loading on the TiO<SUB>2</SUB> nanocrystallites supported on the carbon nanofiber support. Hydrogen evolution was increased significantly by the addition of organic reagents, which acted as a type of sacrificial reagent promoting photocatalysis.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Hydrogen evolution was estimated from water photocatalysis by liquid phase plasma. </LI> <LI> Enhancement of hydrogen evolution was evaluated by liquid phase plasma irradiation. </LI> <LI> Carbon nanofiber was applied as a support for a fixation of TiO<SUB>2</SUB> nanocrystallites. </LI> <LI> Rate of hydrogen evolution was improved by the metal loading on the TiO<SUB>2</SUB> surface. </LI> <LI> Hydrogen evolution was increased significantly by adding of organic reagent into water. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

장주기/대용량 저장을 위한 액체/고체(Slush) 수소 생산 장치의 해외기술 동향분석

이창형(CHANGHYEONG LEE),류주열(JUYEOL RYU),손근(GEUN SOHN),박성호(SUNGHO PARK) 한국수소및신에너지학회 2021 한국수소 및 신에너지학회논문집 Vol.32 No.6

Hydrogen is currently produced from natural gas reforming or industrial process of by-product over than 90%. Additionally, there are green hydrogens based on renewable energy generation, but the import of green hydrogen from other countries is being considered due to the output variability depending on the weather and climate. Due to low density of hydrogen, it is difficult to storage and import hydrogen of large capacity. For improving low density issue of hydrogen, the gaseous hydrogen is liquefied and stored in cryogenic tank. Density of hydrogen increase from 0.081 kg/m³ to 71 kg/m3 when gaseous hydrogen transfer to liquid hydrogen. Density of liquid hydrogen is higher about 800 times than gaseous. However, since density and boiling point of liquid hydrogen is too lower than liquefied natural gas approximately 1/6 and 90 K, to store liquid hydrogen for long-term is very difficult too. To overcome this weakness, this paper introduces storage method of hydrogen based on liquid/solid (slush) and facilities for producing slush hydrogen to improve low density issue of hydrogen. Slush hydrogen is higher density and heat capacity than liquid hydrogen, can be expected to improve these issues.

The effects of hydrogen on the combustion, performance and emissions of a turbo gasoline direct-injection engine with exhaust gas recirculation

Kim, Joonsuk,Chun, Kwang Min,Song, Soonho,Baek, Hong-Kil,Lee, Seung Woo Elsevier 2017 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.42 No.39

<P><B>Abstract</B></P> <P>The effects of hydrogen on the combustion characteristics, thermal efficiency, and emissions of a turbo gasoline direct-injection engine with exhaust gas recirculation (EGR) were investigated experimentally at brake mean effective pressures of 4, 6, and 8 bar at 2000 rpm. Four cases of hydrogen energy fraction (0%, 1%, 3% and 5%) of total fuel energy were studied. Hydrogen energy fraction of total fuel energy was hydrogen energy in the sum of energy of consumed gasoline and added hydrogen. The test results demonstrated that hydrogen addition improved the combustion speed and reduced cycle-to-cycle variation. In particular, cylinder-to-cylinder variation dramatically decreased with hydrogen addition at high EGR rates. This suggests that the operable EGR rate can be widened for a turbo gasoline direct-injection engine. The improved combustion and wider operable EGR rate resulted in enhanced thermal efficiency. However, the turbocharging effect acted in opposition to the thermal efficiency with respect to the EGR rate. Therefore, a different strategy to improve the thermal efficiency with EGR was required for the turbo gasoline direct-injection engine. HC and CO<SUB>2</SUB> emissions were reduced but NO<SUB>X</SUB> emissions increased with hydrogen addition. The CO emissions as a function of engine load followed different trends that depended on the level of hydrogen addition.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Hydrogen effects on the performance of T-GDI engine with EGR are investigated. </LI> <LI> Variations of cycle to cycle and cylinder to cylinder decreased with hydrogen. </LI> <LI> EGR limit was extended by hydrogen. </LI> <LI> ITE increased with hydrogen but trends for ITE were different with engine load. </LI> <LI> HC, CO<SUB>2</SUB> emissions decreased, NO<SUB>X</SUB> emissions increased with hydrogen. </LI> </UL> </P>