Korea, Republic of
The Study on the Internal Temperature Change of Type 3 and Type 4 Composite Cylinder During Filling
Sep 2013
Publication
The number of eco friendly vehicle which is using green energy such as natural gas(NG) and hydrogen(H2) is rapidly increasing in the world. Almost all of the car manufacturers are adopting the pressurizing fuel method to storage gas. The fuel storage system which can pressurize the fuel as high as possible is necessary to maximize the mileage of the vehicle. In Korea the most important issue is that makes sure of safety of the fuel storage system and several tests are performed to verify safety of the composite cylinder especially for Type 3 and Type 4. In this research an empirical study on the internal temperature change of Type 3 and Type 4 composite cylinder during filling is performed by gas cycling test equipment. In order to measure the temperature totally twelve sensors(every four sensors on the top middle and bottom) are installed in each cylinder. As a consequence large amount of compression heat is generated during rapid filling and the result temperature change in Type 4 is greater than Type 3 is confirmed depending on property of the liner material such as thermal conduction and thickness of carbon composite.
Numerical Analysis of the Effects of Ship Motion on Hydrogen Release and Dispersion in an Enclosed Area
Jan 2022
Publication
Hydrogen is an alternative to conventional heavy marine fuel oil following the initial strategy of the International Maritime Organization (IMO) for reducing greenhouse gas emissions. Although hydrogen energy has many advantages (zero-emission high efficiency and low noise) it has considerable fire and explosion risks due to its thermal and chemical characteristics (wide flammable concentration range and low ignition energy). Thus safety is a key concern related to the use of hydrogen. Whereas most previous studies focused on the terrestrial environment we aim to analyze the effects of the ship’s motion on hydrogen dispersion (using commercial FLUENT code) in an enclosed area. When compared to the steady state our results revealed that hydrogen reached specific sensors in 63% and 52% less time depending on vessel motion type and direction. Since ships carry and use a large amount of hydrogen as a power source the risk of hydrogen leakage from collision or damage necessitates studying the correspondence between leakage diffusion and motion characteristics of the ship to position the sensor correctly.
Synthesis of Spherical V-Nb-Mo-Ta-W High-Entropy Alloy Powder Using Hydrogen Embrittlement and Spheroidization by Thermal Plasma
Dec 2019
Publication
V-Nb-Mo-Ta-W high-entropy alloy (HEA) one of the refractory HEAs is considered as a next-generation structural material for ultra-high temperature uses. Refractory HEAs have low castability and machinability due to their high melting temperature and low thermal conductivity. Thus powder metallurgy becomes a promising method for fabricating components with refractory HEAs. Therefore in this study we fabricated spherical V-Nb-Mo-Ta-W HEA powder using hydrogen embrittlement and spheroidization by thermal plasma. The HEA ingot was prepared by vacuum arc melting and revealed to have a single body-centered cubic phase. Hydrogen embrittlement which could be achieved by annealing in a hydrogen atmosphere was introduced to get the ingot pulverized easily to a fine powder having an angular shape. Then the powder was annealed in a vacuum atmosphere to eliminate the hydrogen from the hydrogenated HEA resulting in a decrease in the hydrogen concentration from 0.1033 wt% to 0.0003 wt%. The angular shape of the HEA powder was turned into a spherical one by inductively-coupled thermal plasma allowing to fabricate spherical V-Nb-Mo-Ta-W HEA powder with a d50 value of 28.0 μm.
Study on the Explosion of the Hydrogen Fuel Tank of Fuel Cell Electric Vehicles in Semi-Enclosed Spaces
Dec 2022
Publication
The rise in hydrogen fuel cell electric vehicles (FCEVs) is expected to pose a variety of hazards on the road. Vehicles using hydrogen could cause significant damage owing to hydrogen vapor cloud explosions jet fires caused by leakage or hydrogen tank explosions. This risk is expected to further increase in semi-enclosed spaces such as underground parking lots and road tunnels. Therefore it is necessary to study the fire safety of hydrogen vehicles in semi-enclosed spaces. In this study an experiment on hydrogen tank explosion was performed. In addition the CFD numerical model was verified using the experimental results and the damaging effect due to pressure propagation during hydrogen tank explosions in underground parking lots and road tunnels was analyzed using numerical analysis. From the experiment results the hydrogen tank exploded at about 80 Mpa a maximum incident pressure is generated 267 kPa at a distance of 1.9 m. As a result of numerical analysis based on the experimental results the limit distance that can cause serious injury due to the explosion of a hydrogen tank in a road tunnel or underground parking lot was analyzed up to about 20 m from the point of explosion.
Explosion Characteristics of Hydrogen Gas in Varying Ship Ventilation Tunnel Geometries: An Experimental Study
Apr 2022
Publication
Hydrogen is widely regarded as a key element of prospective energy solutions for alleviating environmental emission problems. However hydrogen is classified as a high-risk gas because of its wide explosive range high overpressure low ignition energy and fast flame propagation speed compared with those of hydrocarbon-based gases. In addition deflagration can develop into detonation in ventilation or explosion guide tunnels if explosion overpressure occurs leading to the explosion of all combustible gases. However quantitative evidence of an increase in the explosion overpressure of ventilation tunnels is unavailable because the explosive characteristics of hydrogen gas are insufficiently understood. Therefore this study investigated an explosion chamber with the shape of a ventilation pipe in a ship compartment. The effect of tunnel length on explosion overpressure was examined experimentally. For quantitative verification the size of the hydrogen gas explosion overpressure was analyzed and compared with experimental values of hydrocarbon-based combustible gases (butane and LPG (propane 98%)). The experimental database can be used for explosion risk analyses of ships when designing ventilation holes and piping systems and developing new safety guidelines for hydrogen carriers and hydrogen-fueled ships.
A Comparative Feasibility Study of the Use of Hydrogen Produced from Surplus Wind Power for a Gas Turbine Combined Cycle Power Plant
Dec 2021
Publication
Because of the increasing challenges raised by climate change power generation from renewable energy sources is steadily increasing to reduce greenhouse gas emissions especially CO2 . However this has escalated concerns about the instability of the power grid and surplus power generated because of the intermittent power output of renewable energy. To resolve these issues this study investigates two technical options that integrate a power-to-gas (PtG) process using surplus wind power and the gas turbine combined cycle (GTCC). In the first option hydrogen produced using a power-to-hydrogen (PtH) process is directly used as fuel for the GTCC. In the second hydrogen from the PtH process is converted into synthetic natural gas by capturing carbon dioxide from the GTCC exhaust which is used as fuel for the GTCC. An annual operational analysis of a 420-MWclass GTCC was conducted which shows that the CO2 emissions of the GTCC-PtH and GTCC-PtM plants could be reduced by 95.5% and 89.7% respectively in comparison to a conventional GTCC plant. An economic analysis was performed to evaluate the economic feasibility of the two plants using the projected cost data for the year 2030 which showed that the GTCC-PtH would be a more viable option.
Temperature Change of a Type IV Cylinder During Hydrogen Fuelling Process
Sep 2009
Publication
The temperature of the hydrogen cylinder needs to be carefully controlled during fuelling process. The maximum temperature should be less than 85℃ according to the ISO draft code. If the fuelling period is reduced the maximum temperature should increase. In this study temperature change of a Type IV cylinder was measured during the hydrogen fuelling process up to 35 MPa. Fuelling period was 3 to 5 minutes. Twelve thermocouples were installed to measure inside gas temperature and seven were attached on the outside of the cylinder. An infrared camera was also used for measuring temperature distribution of outside of cylinder. The maximum gas temperature was higher than 85℃ inside of the cylinder. Significant temperature difference between the upper and lower part of the vessel was observed. Temperature near the plug and the valve was quickly increased and maintained higher than that of the other region. Temperature increases for the partial refuelling process were also discussed.
Strategy for Selecting an Optimal Propulsion System of a Liquefied Hydrogen Tanker
Jan 2017
Publication
This study proposed a strategy for selecting an optimal propulsion system of a liquefied hydrogen tanker. Four propulsion system options were conceivable depending on whether the hydrogen BOG (boil-off gas) from the cryogenic cargo tanks was used for fuel or not. These options were evaluated in terms of their economic technological and environmental feasibilities. The comparison scope included not only main machinery but also the BOG handling system with electric generators. Cost-benefit analysis life-cycle costing including carbon tax and an energy efficiency design index were used as measures to compare the four alternative systems. The analytic hierarchy process made scientific decision-making possible. This methodology provided the priority of each attribute through the use of pairwise comparison matrices. Consequently the propulsion system using LNG with hydrogen BOG recovery was determined to be the optimal alternative. This system was appropriate for the tanker that achieved the highest evaluation score.
Recent Progress Using Solid-State Materials for Hydrogen Storage: A Short Review
Feb 2022
Publication
With the rapid growth in demand for effective and renewable energy the hydrogen era has begun. To meet commercial requirements efficient hydrogen storage techniques are required. So far four techniques have been suggested for hydrogen storage: compressed storage hydrogen liquefaction chemical absorption and physical adsorption. Currently high-pressure compressed tanks are used in the industry; however certain limitations such as high costs safety concerns undesirable amounts of occupied space and low storage capacities are still challenges. Physical hydrogen adsorption is one of the most promising techniques; it uses porous adsorbents which have material benefits such as low costs high storage densities and fast charging–discharging kinetics. During adsorption on material surfaces hydrogen molecules weakly adsorb at the surface of adsorbents via long-range dispersion forces. The largest challenge in the hydrogen era is the development of progressive materials for efficient hydrogen storage. In designing efficient adsorbents understanding interfacial interactions between hydrogen molecules and porous material surfaces is important. In this review we briefly summarize a hydrogen storage technique based on US DOE classifications and examine hydrogen storage targets for feasible commercialization. We also address recent trends in the development of hydrogen storage materials. Lastly we propose spillover mechanisms for efficient hydrogen storage using solid-state adsorbents.
Layered Transition Metal Selenophosphites for Visible Light Photoelectrochemical Production of Hydrogen
Jun 2021
Publication
The growing consumption of global energy has posed serious challenges to environmental protection and energy supplies. A promising solution is via introducing clean and sustainable energy sources including photoelectrochemical hydrogen fuel production. 2D materials such as transition metal trichalcogenphosphites (MPCh3) are gaining more and more interest for their potential as photocatalysts. Crystals of transition metal selenophosphites namely MnPSe3 FePSe3 and ZnPSe3 were tested as photocatalysts for the hydrogen evolution reaction (HER). ZnPSe3 is the one that exhibited the lowest overpotential and the higher response to the light during photocurrent experiments in acidic media. For this reason among the crystals in this work it is the most promising for the photocatalyzed production of hydrogen.
Non-precious Electrocatalysts for Oxygen Evolution Reaction in Anion Exchange Membrane Water Electrolysis: A Mini Review
Sep 2021
Publication
Anion exchange membrane water electrolysis (AEMWE) is considered the next generation of green hydrogen production method because it uses low-cost non-noble metal oxide electrocatalyst electrodes and can store highpurity hydrogen under high pressure. However the commercialization of AEMWE with non-precious metal oxide electrocatalysts is challenging due to low electrocatalytic activity and durability. Overcoming the low kinetics caused by four-electron transfer is vital in addressing the low activity of non-noble metal oxide electrocatalysts for oxygen evolution reaction. This article overviews the synthesis methods and related techniques for various anode electrodes applied to AEMWE systems. We highlight effective strategies that have been developed to improve the performance and durability of the non-precious electrocatalysts and ensure the stable operation of AEMWE followed by a critical perspective to encourage the development of this technology.
The Enhanced Hydrogen Storage Capacity of Carbon Fibers The Effect of Hollow Porous Structure and Surface Modification
Jul 2021
Publication
In this study highly porous carbon fiber was prepared for hydrogen storage. Porous carbon fiber (PCF) and activated porous carbon fiber (APCF) were derived by carbonization and chemical activation after selectively removing polyvinyl alcohol from a bi-component fiber composed of polyvinyl alcohol and polyacrylonitrile (PAN). The chemical activation created more pores on the surface of the PCF and consequently highly porous APCF was obtained with an improved BET surface area (3058 m2 g−1) and micropore volume (1.18 cm3 g−1) compare to those of the carbon fiber which was prepared by calcination of monocomponent PAN. APCF was revealed to be very efficient for hydrogen storage its hydrogen capacity of 5.14 wt% at 77 K and 10 MPa. Such hydrogen storage capacity is much higher than that of activated carbon fibers reported previously. To further enhance hydrogen storage capacity catalytic Pd nanoparticles were deposited on the surface of the APCF. The Pd-deposited APCF exhibits a high hydrogen storage capacity of 5.45 wt% at 77 K and 10 MPa. The results demonstrate the potential of Pd-deposited APCF for efficient hydrogen storage.
Highly Selective Porous Separator with Thin Skin Layer for Alkaline Water Electrolysis
Feb 2022
Publication
Advanced porous separators with thin selective skin layers to reduce the hydrogen permeation are developed for applications in alkaline water electrolysis. A thin skin layer based on crosslinked polyvinyl alcohol (cPVA) is fabricated on a porous substrate by a facile and scalable ultrasonic spray coating process. As the number of ultrasonic spraying cycles increases the resulting separator demonstrates a decrease in the large-diameter pore fraction an increase in the bubble-point pressure and a reduction in the hydrogen permeability without a significant increase in the areal resistance. As a result the optimized separator with a cPVA skin layer combines a low ionic resistance of 0.267 Ω cm2 a high bubble point pressure of 2.71 bar and a low hydrogen permeability of 1.12 × 10− 11 mol cm− 2 s − 1 bar− 1 . The electrolytic cell assembled with cPVAZ-30 achieves current densities of 861 mA cm− 2 and 1890 mA cm− 2 at 2.0 V and 2.6 V respectively in a 30 wt% KOH electrolyte solution at 80 ◦C.
Numerical Analysis for Hydrogen Flame Acceleration during a Severe Accident Initiated by SBLOCA in the APR1400 Containment
Jan 2022
Publication
We performed a hydrogen combustion analysis in the Advanced Power Reactor 1400 MWe (APR1400) containment during a severe accident initiated by a small break loss of coolant accident (SBLOCA) which occurred at a lower part of the cold leg using a multi-dimensional hydrogen analysis system (MHAS) to confirm the integrity of the APR1400 containment. The MHAS was developed by combining MAAP GASFLOW and COM3D to simulate hydrogen release distribution and combustion in the containment of a nuclear power plant during the severe accidents in the containment of a nuclear power reactor. The calculated peak pressure due to the flame acceleration by the COM3D using the GASFLOW results as an initial condition of the hydrogen distribution was approximately 555 kPa which is lower than the fracture pressure 1223 kPa of the APR1400 containment. To induce a higher peak pressure resulted from a strong flame acceleration in the containment we intentionally assumed several things in developing an accident scenario of the SBLOCA. Therefore we may judge that the integrity of the APR1400 containment can be maintained even though the hydrogen combustion occurs during the severe accident initiated by the SBLOCA.
Simulator Development of Virtual Experience and Accident Scenarios of Hydrogen Stations for Safety
Sep 2007
Publication
Nowadays 4 type hydrogen stations have been demonstrated in Korea for preparing hydrogen economy. This simulator is consists of virtual experience modules and virtual accident scenarios of 4 type hydrogen stations. Virtual experience modules show the performance properties through a movie or a virtual reality technology. Also they provide an explanation of hydrogen station equipment and a guide for operators immediately after the accident. Virtual accident scenario modules show accident simulations based on modelling equations as 3D virtual reality. These modules could choose the sham accident for every kind of a station after categorizing all possible accidents in a station A Commercialized CFD program based on hydrogen dispersion model theory shows a movie of accident simulations. The result of a simulator has been developed as web applications. And will be applied to training materials and public relations for a user concerned about hydrogen stations.
Compatibility and Suitability of Existing Steel Pipelines for Transport of Hydrogen and Hydrogen-natural Gas Blends
Sep 2017
Publication
Hydrogen is being considered as a pathway to decarbonize large energy systems and for utility-scale energy storage. As these applications grow transportation infrastructure that can accommodate large quantities of hydrogen will be needed. Many millions of tons of hydrogen are already consumed annually some of which is transported in dedicated hydrogen pipelines. The materials and operation of these hydrogen pipeline systems however are managed with more constraints than a conventional natural gas pipeline. Transitional strategies for deep decarbonization of energy systems include blending hydrogen into existing natural gas systems where the materials and operations may not have the same controls. This study explores the hydrogen compatibility of existing pipeline steels and the suitability of these steels in hydrogen pipeline systems. Representative fracture and fatigue properties of pipeline grade steels in gaseous hydrogen are summarized from the literature. These properties are then considered in idealized design life calculations to inform materials performance for a typical gas pipeline.
Low-carbon Energy Transition With the Sun and Forest: Solar-driven Hydrogen Production from Biomass
Nov 2021
Publication
There is a need to derive hydrogen from renewable sources and the innovative stewardship of two natural resources namely the Sun and forest could provide a new pathway. This paper provides the first comparative analysis of solar-driven hydrogen production from environmental angles. A novel hydrogen production process proposed in this paper named Solar-Driven Advanced Biomass Indirect-Gasification (SABI-Hydrogen) shows promise toward achieving continuous operation and scalability the two key challenges to meet future energy needs. The calculated Global Warming Potential for 1 kg of solar-driven hydrogen production is 1.04 kg CO2-eq/kg H2 less than half of the current biomass gasification process which emits 2.67 kg CO2-eq/kg H2. Further SABI-Hydrogen demonstrates the least-carbon intensive pathway among all current hydrogen production methods. Thus solar-driven hydrogen production from biomass could lead to a sustainable supply essential for a low-carbon energy transition.
Exploring Future Promising Technologies in Hydrogen Fuel Cell Transportation
Jan 2022
Publication
The purpose of this research was to derive promising technologies for the transport of hydrogen fuel cells thereby supporting the development of research and development policy and presenting directions for investment. We also provide researchers with information about technology that will lead the technology field in the future. Hydrogen energy as the core of carbon neutral and green energy is a major issue in changing the future industrial structure and national competitive advantage. In this study we derived promising technology at the core of future hydrogen fuel cell transportation using the published US patent and paper databases (DB). We first performed text mining and data preprocessing and then discovered promising technologies through generative topographic mapping analysis. We analyzed both the patent DB and treatise DB in parallel and compared the results. As a result two promising technologies were derived from the patent DB analysis and five were derived from the paper DB analysis.
A Numerical Simulation of Hydrogen Diffusion for the Hydrogen Leakage from a Fuel Cell Vehicle in an Underground Parking Garage
Sep 2011
Publication
In the present study the diffusion process of hydrogen leaking from a FCV (Fuel Cell Vehicle) in an underground parking garage is analyzed by numerical simulations in order to assess the risk of a leakage accident. The temporal and spatial evolution of the hydrogen concentration as well as the flammable region in the parking garage was predicted numerically. The effects of the leakage flow rate and an additional ventilation fan were investigated to evaluate the ventilation performance to relieve the accumulation of the hydrogen gas. The volume of the flammable region shows a non-linear growth in time and rapidly increases eventually. The present numerical analysis can provide a physical insight and quantitative data for safety of various hydrogen applications.
Preference Structure on the Design of Hydrogen Refueling Stations to Activate Energy Transition
Aug 2020
Publication
As a countermeasure to the greenhouse gas problem the world is focusing on alternative fuel vehicles (AFVs). The most prominent alternatives are battery electric vehicles (BEV) and fuel cell electric vehicles (FCEVs). This study examines FCEVs especially considering hydrogen refueling stations to fill the gap in the research. Many studies suggest the important impact that infrastructure has on the diffusion of AFVs but they do not provide quantitative preferences for the design of hydrogen refueling stations. This study analyzes and presents a consumer preference structure for hydrogen refueling stations considering the production method distance probability of failure to refuel number of dispensers and fuel costs as core attributes. For the analysis stated preference data are applied to choice experiments and mixed logit is used for the estimation. Results indicate that the supply stability of hydrogen refueling stations is the second most important attribute following fuel price. Consumers are willing to pay more for green hydrogen compared to gray hydrogen which is hydrogen produced by fossil fuels. Driver fuel type and perception of hydrogen energy influence structure preference. Our results suggest a specific design for hydrogen refueling stations based on the characteristics of user groups.
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