• Journal of Hydrogen and New Energy
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• v.33 no.5
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• pp.507-514
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• 2022

There is growing interest in sustainable energy sources that can reduce fossil fuel dependence and environmental pollution while meeting rapidly growing energy demands. Hydrogen have been investigated as one of the ideal alternative energies because it has relatively high efficiency without emitting pollutants. The light-sensitized enzymatic (LSE) system, which uses hydrogenase-enzymes, is one of the methods towards economically feasible system configurations that enhance the rate of hydrogen generation. Hydrogenase is an enzyme that catalyzes a reversible reaction that oxidizes molecular hydrogen or produces molecular hydrogen from protons and electrons. In this paper, utilization of [NiFe]-hydrogenase (from Pyrococcus furiosus) in photoelectrochemical hydrogen production system such as handling, immobilization, physicochemical and electrochemical analysis, process parameters, etc. was introduced.

• Journal of Hydrogen and New Energy
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• v.29 no.3
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• pp.251-259
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• 2018

Metal hydride based hydrogen storage under moderate temperature and pressure gives the safety advantage over the gas and liquid storage methods. Still solid-state hydrogen storage including metal hydride is below the DOE target level for automotive applications, but it can be adapted to stationary or miliary application reasonably. In order to develop a modular solid state hydrogen storage system that can be applied to a distributed power supply system composed of renewable energy - water electrolysis - fuel cell, the heat transfer and hydrogen storage characteristics of the metal hydride necessary for the module system design were investigated using AB5 type metal hydride, LCN2 ($La_{0.9}Ce_{0.1}Ni_5$). The planetary high energy mill (PHEM) treatment of LCN2 confirmed the initial hydrogen storage activation and hydrogen storage capacity through surface modification of LCN2 material. Expanded natural graphite (ENG) addition to LCN2, and compression molding at 500 atm improved the thermal conductivity of the solid hydrogen storage material.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.10
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• pp.901-909
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• 2012

This paper describes characteristics of solid-state $NaBH_4$ hydrogen generation and supply system for fuel cell UAV. Flow rate and pressure of the generated hydrogen were dramatically changed during $NaBH_4$ decomposition using acid. Hydrogen supply was stabilized by a self-pressurized reactor, and hydrogen stabilization method was introduced. For hydrogen generation in below zero-temperature, hydrochloric acid was diluted by propylene glycol-water mixtures. Solid-state $NaBH_4$hydrogen generation and supply system was designed. Basic operation experiments was performed to reveal the characteristics of this hydrogen generation system.

• Journal of Hydrogen and New Energy
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• v.31 no.6
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• pp.558-563
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• 2020

Hydrogen is attracting attention as an alternative energy source as an eco-friendly fuel without emitting environmental pollutants. In order to use hydrogen as an energy source, technologies such as hydrogen production and storage must be used, and new storage methods are being studied. In this study, the behavior of hydrogen in the storage tank were numerically studied under high-pressure hydrogen discharge conditions in a Type III hydrogen tank. Numerical results were compared with the experimental value and the results were quantitatively analyzed to verify the numerical implementation. With the results of pressure and temperature values under a given discharge condition, the Redich-Kwong gas model showed the adequate models with the smallest error between numerical and experimental results.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.5
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• pp.695-702
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• 2010

Numerical analysis information will be very useful to improve fluid system. General information about an internal gas flow is presented by numerical analysis approach. Relating with hydrogen compressing system, which have an important role in hydrogen energy utilization, this should be a useful tool to observe the flow quickly and clearly. Flow characteristic analysis, including pressure and turbulence kinetic energy distribution of hydrogen gas coming to the cylinder of a reciprocating compressor are presented in this paper. Suction-passage model is designed based on real model of hydrogen compressor. Pressure boundary conditions are applied considering the real condition of operating system. The result shows pressure and turbulence kinetic energy are not distributed uniformly along the passage of the Hydrogen system. Path line or particles tracks help to demonstrate flow characteristics inside the passage. The existence of vortices and flow direction can be precisely predicted. Based on this result, the design improvement, such as reducing the varying flow parameters and flow reorientation should be done. Consequently, development of the better hydrogen compressing system will be achieved.

• Nuclear Engineering and Technology
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• v.16 no.4
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• pp.217-223
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• 1984

The feasibility of not employing recombiners rather using the postaccident Purge system alone to control hydrogen concentration in the containment following a LOCA, is analyzed in this paper. For this study, the hydrogen concentration in the containment, hydrogen removal through the purge system, and additional off-site dose due to hydrogen purge were calculated. The economic justification of a hydrogen recombiner system (2 recombiners) was also investigated by using the cost benefit concept. As a result, the purge system is sufficient to maintain the hydrogen concentration at a safe level without hydrogen recombiners, and it meets the dose limit requirements set forth in 10 CFR part 100. A hydrogen recombiner system would be justified based on cost-benefit concept for common use in a site with 4 units or more.

• Journal of the Korean Institute of Gas
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• v.11 no.4
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• pp.41-46
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• 2007

The residential fuel cell system was modeled as a box-shaped chamber with vent openings, filled with various components such as reformer, desulfurizer, fuel cell stack and humidifier. When the vent openings are 1% of the total surface and hydrogen leakage 1%, hydrogen concentration is around 0.1% higher than the other regions from leak points in the chamber at 30 seconds and hydrogen concentration is increased from 0.3% to 0.7% in the upper region of the system after 200 seconds. When the vent openings are 1% of the total surface and hydrogen leakage 1%, 3%, 5%, the steady state result of CFD, 5% of hydrogen leakage is reached the lowest ignition limit in the system. When the vent openings are 2% of the total surface and hydrogen leakage 1%, hydrogen concentration is increased in the bottom of the system for 60 seconds. After 250 seconds, hydrogen concentration is reached the steady state in the system. As the vent opening of the total surface increased from 1% to 2%, averaged hydrogen mole fraction is under 1% in the system, however, upper regions of the system from the hydrogen leakage points are shown over 1% of hydrogen mole fraction.

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.274-276
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• 2005

This paper present an effective modeling scheme of SPE cell system for hydrogen production. As oxygen and hydrogen produced by water electrolysis using SPE are high purity, we can use oxygen in biomedical and hydrogen could be used in many ways. Recently, it is under the eye as a surplus power storage system. PSCAD/EMTDC model of SPE cell system for hydrogen production to efficiently utilize solar cell energy is showed in this paper. The simulated results are then verified by comparing them with the actual values obtained from the data acquisition system. Authors are sure that it is a useful method to the researchers who study SPE cell system for hydrogen production.

• Journal of Hydrogen and New Energy
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• v.35 no.3
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• pp.290-299
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• 2024

In this study, a theoretical study was conducted on the pre-cooling temperature of hydrogen gas and the heat exchanger area in a small-scale liquefied hydrogen system. The small-scale liquefaction system was built and liquid hydrogen production experiments were performed. In this process, the temperature of precooled hydrogen gas was measure to be about 120 K, and then the possibility of a cause was analyzed through pressure analysis of hydrogen gas and container, and analysis of the amount of liquid hydrogen produced. It was found that some reasonable results were obtained from the theoretical approaches. Based on this theoretical approach, we aim to improve the production of liquid hydrogen by optimizing the heat exchange area according to flow rate.

• Journal of Hydrogen and New Energy
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• v.35 no.3
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• pp.300-309
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• 2024

Hydrogen utilization in the transportation sector, which relies on fossil fuels, can significantly reduce greenhouse gas by using to hydrogen fuel cell vehicles, and its adoption depends performance of hydrogen refueling station. The present study developed a model to simulate the back-to-back filling process of heavy duty hydrogen fuel cell vehicles at hydrogen refueling stations using a cascade method. And its quantitatively evaluated hydrogen refueling station performance by simulating various mass flow rates and storage tank capacity combinations, analyzing vehicle state of charge (SOC) of vehicles. In the cascade refueling system, the capacity of the high-pressure storage tank was found to have the greatest impact on the reduction of filling time and improvement of efficiency.