• 한국수소및신에너지학회논문집
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• 제31권2호
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• pp.184-193
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• 2020

One of the technical methods to increase the volumetric energy density of hydrogen is to pressurize the gaseous hydrogen and then contain it in a rigid vessel. Especially for automotive systems, the compressed hydrogen storage can be found in cars as well as at refueling stations. During the charging the pressurized hydrogen into a vessel, the temperature increases with the amount of stored hydrogen in the vessel. The temperature of the vessel should be controlled to be less than a limitation for ensure stability of material. Therefore, the accurate estimation of temperature is of significance for safely storing the hydrogen. In this work, three well-known cubic equations of state (EOSs) were adopted to examine the accuracy in regenerating thermodynamic properties of hydrogen within the temperature and pressure ranges for the compressed hydrogen storage. The formulations representing molar volume, internal energy, enthalpy, and entropy were derived for Redlich-Kwong (RK), Soave-Redlioch-Kwong (SRK), and Peng-Robinson (PR) EOSs. The calculated results using the EOSs were compared with literature data given by NIST. It was revealed that the accuracies of RK and SRK EOSs were satisfactorily compatible and better than the results by PR EOS.

• 소성∙가공
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• 제28권4호
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• pp.203-211
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• 2019

In this study, the weight of type IV pressure vessel is optimized through the burst pressure condition using the finite element analysis (FEA) based on the genetic algorithm (GA). The optimization design variables include the thickness of composite layers and the winding angles. The optimized design variables are validated using the numerical simulations for the pressure vessel. Consequently, the weight is decreased by about 6.5% as compared to the previously reported results for Type III pressure vessel. Additionally, a method which reduces the entire optimization time is proposed. In the original method, the population size is constant across all generations. However, the proposed method could reduce the workload through the reduction of the population size by half for every 25 generations. Thus, the proposed method is observed to increase the weight by about 0.1%, however, the working time for the optimization could be decreased by about 46.5%.

• 한국가스학회지
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• 제27권3호
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• pp.116-122
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• 2023

저탄소 친환경에너지 정책이 진행으로 인해 수소 공급을 위한 수소충전소의 증가됨에 따라 사고발생 위험도 커지고 있다. 실제 압력용기는 제조과정에서 발생할 수 있는 노치와 기공, 개재물 등의 결함이 존재할 수 있다. 따라서 내압이 작용하고 있는 압력용기에 균열이 존재할 경우에 대한 압력용기의 건전성을 평가하는 것은 필요하다. 본 연구에서는 표면균열이 있는 수소충전용 압력용기의 구조안전성을 평가하기 위해 3차원 유한요소해석을 이용하였으며, 표면균열의 형상은 일반적으로 많이 사용되는 반타원 형상을 적용하여 균열의 형상 및 응력비에 대한 균열진전 특성을 비교하였다. 향후, 이러한 결과를 이용하여 파괴역학을 고려한 압력용기의 잔존수명 예측에 활용할 예정이다.

• 한국수소및신에너지학회논문집
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• 제22권3호
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• pp.363-371
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• 2011

In this paper, a three-dimensional hydrogen desorption model is developed to precisely study the hydrogen desorption kinetics and resultant heat and mass transport phenomena in metal hydride hydrogen storage vessels. The metal hydride hydrogen desorption model, i.e. governed by the conservation of mass, momentum, and thermal energy is first experimentally validated against the temperature evolution data measured on a cylindrical $LaNi_5$ metal hydride vessel. The equilibrium pressure used for hydrogen desorption simulations is derived as a function of H/M atomic ratio and temperature based on the experimental data in the literature. The numerical simulation results agree well with experimental data and the 3D desorption model successfully captures key experimental trends during hydrogen desorption process. Both the simulation and experiment display an initial sharp decrease in the temperature mainly caused by relatively slow heat supply rate from the vessel external wall. On the other hand, the effect of heat supply becomes influential at the latter stages, leading to smooth increase in the vessel temperature in both simulation and experiment. This numerical study provides the fundamental understanding of detailed heat and mass transfer phenomena during hydrogen desorption process and further indicates that efficient design of storage vessel and heating system is critical to achieve fast hydrogen discharging performance.

• 한국가스학회지
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• 제27권2호
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• pp.95-103
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• 2023

본 논문에서는 가스압력을 고려할 때 수소가스 저장용기(Type 1)의 거동특성을 평가하기 위해 ISO 18119의 노치형상에 따라 수소가스 저장용기에서 발생한 VMS(von Mises stress)을 유한요소법으로 해석하였다. 해석결과에 따르면 길이방향 노치에서 발생한 최대 VMS가 원주방향 노치보다 높게 발생하였다. 또한, 저장용기의 거동시 발생한 응력을 VMS와 재료의 항복강도 비인 응력비로 분석하였다. 해석결과에 따르면 노치가 길이방향으로 형성된 저장용기의 경우 가스압력 50 MPa에서 저장용기 내부와 외부가 각각 0.85와 0.50로 증가하였으나 1보다 낮게 분석되었다.

• 한국수소및신에너지학회논문집
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• 제34권1호
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• pp.32-37
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• 2023

In this study, in order to propose a integrity evaluation for type IV high aspect ratio hydrogen storage vessel, a numerical analysis of the hoop tensile test and pressure test was performed using FEM software, and the results of the actual physical property test were reviewed. The property test and numerical analysis were compared, and very similar results were obtained with deviations of maximum tensile strength of 4.75% and fiber direction stress of 5.39%.

• Nuclear Engineering and Technology
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• 제45권6호
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• pp.767-790
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• 2013

MAAP4 is a computer code that can simulate the response of a light water reactor power plant during severe accident sequences, including actions taken as part of accident management. The code quantitatively predicts the evolution of a severe accident starting from full power conditions given a set of system faults and initiating events through events such as core melt, reactor vessel failure, and containment failure. Furthermore, models are included in the code to represent the actions that could mitigate the accident by in-vessel cooling, external cooling of the reactor pressure vessel, or cooling the debris in containment. A key element tied to using a code like MAAP4 is an uncertainty analysis. The purpose of this paper is to present a MAAP4 based analysis to examine the sensitivity of a key parameter, in this case hydrogen production, to a set of model parameters that are related to a Level 2 PRA analysis. The Level 2 analysis examines those sequences that result in core melting and subsequent reactor pressure vessel failure and its impact on the containment. This paper identifies individual contributors and MAAP4 model parameters that statistically influence hydrogen production. Hydrogen generation was chosen because of its direct relationship to oxidation. With greater oxidation, more heat is added to the core region and relocation (core slump) should occur faster. This, in theory, would lead to shorter failure times and subsequent "hotter" debris pool on the containment floor.

• 한국안전학회지
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• 제7권3호
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• pp.66-72
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• 1992

An experimental study was carried out to analyse the explosion characteristics of flammable gas-air mixtures. Used flammable gases were hydrogen, methane, acethylene, ethylene and pro-pane, explosion Pressure, explosoin pressure rising rate, and flame propagation velocity were measured experimentaly. The maximum explosion pressure and rising rate of flammmalbe gas air mixtures were appeared at the range of slightly higher concentration than the stoichiometric concentration. Initial pressure before explosion was controlled from 0.6 to 2.0kg/cm absolutly. Explosion pressure was increased with increment of the initial pressure, and the relationship between initial pressure and explosion pressure was Pe = KPi. The effect of vessel size on explosion characteristics was also analysed In this experiment. Explosion pressure was increased with in-creasing the vessel size, otherwise explosion pressure rising rate was decreased. When we locate a dummy material in vessel explosion pressure was decreased with increasing the dummy volume but exlosion pressure rising rate was increased.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.193-196
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• 2007

We developed and tested the high pressure hydrogen gas cylinder(type4) for fuel cell vehicle. The working pressure is 350bar. We conducted material tests, production tests and design qualification tests on the developed cylinders according to modified NGV2-2000(hydrogen). The high pressure hydrogen gas cylinder met all the design qualification requirements of ANSI/CSA NGV2-2000 and acquired NGV2 certification from independent inspection agency.

• Composites Research
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• 제29권2호
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• pp.60-65
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• 2016

본 연구에서는 Type IV 수소 압력용기 시제품의 충격하중 조건에 따른 구조 건전성을 분석하고자 유한요소해석과 FBG 센서 삽입을 통한 실시간 모니터링 실험을 수행하여 결과를 분석하였다. 플라이 모델링 기법을 활용한 유한요소해석을 통해 FBG 센서를 삽입할 수소 압력용기의 취약부 선정 및 가압 조건을 제시하였으며, 실험을 진행할 기초 정보를 확보하였다. 실제 용기제작에 앞서 시편 실험을 통해 FBG 센서의 삽입방식 신뢰성을 확보하였으며, 이후 해당 결과를 활용하여 필라멘트 와인딩 공정에 적용하였다. 비충격 가압 피로실험과 총 4회의 충격 피로실험을 수행하였다. 실험결과 비충격 가압 피로실험에서는 해석과 동일한 거동을 보였으며, 4회의 충격 피로실험에서는 용기의 충전 시간이 점진적으로 증가하고 충전률은 감소하는 것을 확인하였다.