• 기계와재료
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• v.24 no.1
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• pp.26-35
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• 2012

가스액화플랜트는 질소, 산소, 헬륨 등 고순도의 가스를 효율적으로 저장 및 운송을 위해 가스를 액체로 변환하는 플랜트로, 대표적인 플랜트로는 질소, 산소, 아르곤 등의 가스를 생산하는 공기분리플랜트, 헬륨액화플랜트, 수소액화플랜트, 천연가스액화플랜트 등이 있다. 질소, 산소, 수소 등의 가스는 산업의 전반적인 분야에서 널리 사용되고 있으며, 국내의 경우 철강, 반도체, 디스플레이제조산업 등 가스 다소비 분야의 비약적인 발전에 따라 급격하게 수요가 증가하고 있는 상황이다. 대용량의 가스액화플랜트는 원료로부터 불순물을 제거하고, 팽창 또는 열교환 과정을 통해 가스를 액체로 변환하는 극저온기술로 주로 구성되며, 이와 같은 과정은 압축기, 열교환기, 증류탑, 팽창터빈, 콜드박스 등의 구성요소에 의해 구현된다. 따라서 가스액화플랜트에서 효율적인 극저온의 생성 및 유지는 플랜트의 경제성 제고를 위해 핵심적인 요소이다.

• Journal of Hydrogen and New Energy
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• v.15 no.3
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• pp.175-186
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• 2004

In this paper, we developed the dynamic model of a fuel cell system suitable for controller design and system operation. The transient phenomena captured in the model include the flow characteristics and inertia dynamics of the compressor, the intake manifold filling dynamics, oxygen partial pressures and membrane humidity on the fuel cell voltage. In the simulations, we paid attention to the transient behavior of stack voltage and compressor pressure, stoichiometric ratio. Simulation results are presented to demonstrate the model capability. For load current following, stack voltage dynamic characteristics are plotted to understand the Electro-chemistry involved with the fuel cell system. Compressor pressure and stoichiometric ratio are strongly coupled, and independent parameters may interfere with each other, dynamic response, undershoot and overshoot.

• Journal of Hydrogen and New Energy
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• v.14 no.3
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• pp.236-246
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• 2003

This paper focuses on developing a model of a PEM fuel cell stack and to integrate it with realistic model of the air supply system for fuel cell vehicle application. The fuel cell system model is realistically and accurately simulated air supply operation and its effect on the system power and efficiency using simulation tool Matlab/Simulink. The Peak performance found at a pressure ratio of 3, and it give a 15mV increase per cell. The limit imposed is a minimum SR(Stoichiometric Ratio) of 2 at low fuel cell load and 2.5 at high fuel cell load.

• Journal of Hydrogen and New Energy
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• v.22 no.6
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• pp.895-904
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• 2011

Stratified charge has been thought as one of the ways to avoid a sharp pressure rise on HCCI combustion. The purpose of this study is to evaluate the potential of stratified charge for reducing PRR on HCCI combustion. The pre-mixture with thermal, mixing and EGR stratifications is charged in Rapid Compression Machine. After that, the pre-mixture is compressed and in that process, in-cylinder gas pressure and temperature are analyzed. Additionally numerical calculation with multi-zones modeling is run to know the potential of stratified charge for reducing PRR.

• Journal of Hydrogen and New Energy
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• v.31 no.2
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• pp.259-264
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• 2020

In this study, comparison study has been performed between two-stage compression and a vapor-recompression refrigeration cycle and a liquefaction using LNG cold heat. When using a first method using two-stage compression and a refrigeration cycle, at least three compressors are required, however when using LNG cold heat, no compressor is required since carbon dioxide can be pumped after condensing with the heat exchange with -160℃ of LNG. Through this study, we can save more than one hundred million KRW annually by using LNG cold heat instead of using gas compression and refrigeration cycle.

• Journal of Hydrogen and New Energy
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• v.34 no.5
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• pp.549-554
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• 2023

In this paper, three kinds of studies have been completed to obtain highly purified carbon dioxide having more than 7N purity as an electronic grade quality. PRO/II with PROVISION release January 2023 from AVEVA company was used, and Peng-Robinson equation of the state model with Twu's alpha function was selected for the modeling of the cryogenic distillation process. When using LN2 cold heat, we can obtain highest recovery of carbon dioxide as a bottom product for a cryogenic distillation column.

• Journal of the Korean Institute of Gas
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• v.24 no.1
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• pp.41-48
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• 2020

This study performed a quantitative risk assessment for hydrogen-CNG complex refueling stations. Individual and societal risks were calculated by deriving accident scenarios that could occur at hydrogen and CNG refueling stations and by considering the frequency of accidents occurring for each scenario. As a result of the risk assessment, societal risk levels were within the acceptable range. However, individual risk has occurred outside the allowable range in some areas. To identify and manage risk components, high risk components were discovered through risk contribution analysis. High risks at the hydrogen-CNG complex refueling station were large leakage from CNG storage containers, compressors, and control panels. The sum of these risks contributed to approximately 88% of the overall risk of the fueling station. Therefore, periodic and intensive safety management should be performed for these high-risk elements.

• Journal of Energy Engineering
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• v.28 no.4
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• pp.1-7
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• 2019

In response to the recent increase in demand for hydrogen stations, the Ministry of Trade and Industry has enacted and promulgated special notifications to enable the installation of hydrogen stations in the form of the combined complex in existing automotive fuel supply facilities such as LPG, CNG, and gas stations. Hydrogen multi energy filling stations haven't been operated yet in Korea till the establishment of special standards, so it is necessary create special standards by considering all Korean environmental characteristics such as four seasons and daily crossings. In this study, we collected and analyzed the charging data of Ulsan LPG-Hydrogen Multi Fueling Station installed for the first time in Korea. The data are hourly temperature and pressure data from compressors, storage vessels and dispensers. We used the data collected for a year, including the highest temperature and the lowest temperature in Ulsan to compare seasonal characteristics. As a result, it was found that the change of the outside temperature affects the initial temperature of the vehicle's container of the hydrogen car, which finally affects the charging time and the charging speed of the vehicle. There was no effect on vehicle containers because the limit temperature suggested by the Korean Hydrogen Station Standard(KGS FP217) and the US Filling Protocol(SAE J2601) was not exceeded.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.10
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• pp.1178-1183
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• 2004

The purpose of this study was to investigate the influence of compression ratio on engine performance in a LPG(Liquefied Petroleum Gas) engine converted from a diesel engine. In ordor to determine the ideal compression ratio, a variable compression ratio 4-cylinder engine was developed. Retrofitting a diesel engine into a LPG engine is technically very complicated compared to a gasoline to LPG conversion. The cylinder head and the piston crown were modified to bum LPG in the engine. Compression ratios were increased from 8 to 10 in an increment of 0.5, the ignition timing was controlled to be at MBT(Minimum Spark Advance for Best Torque) for each case.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.1
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• pp.39-49
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• 2000

This paper presents the modeling approach that can predict transient behavior of rotary compressor. Mass and energy conservation laws are applied to the control volume, real gas state equation is used to obtain thermodynamic properties of refrigerant. The valve equation is solved to analyze discharge process also. Dynamic analysis of vane and roller is carried out to gain friction work. From the above modeling, the performance of rotary compressor with radial clearance and friction loss is investigated numerically. The performance of each refrigerant is estimated, respectively by applying R12, R134a, and R290/ R600a mixture.