• 신재생에너지
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• 제3권2호
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• pp.60-67
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• 2007

This paper describes the design and integration of the wind-fuel cell hybrid system. The hybrid system components included a wind turbine, an electrolyzer (for generation of H2), a PEMFC (Proton Exchange Membrane Fuel Cell), hydrogen storage tank and BOP (Balance of Plant) system. The energy input is entirely provided by a wind turbine. A DC-DC converter controls the power input to the electrolyzer, which produces hydrogen and oxygen form water. The hydrogen used the fuel for the PEMFC. Hydrogen may be produced and stored in high pressure tank by hydrogen gas booster system. Wind conditions are changing with time of day, season and year. So, wind power is a variable energy source. The main purpose with these WT-FC hybrid system is to store hydrogen by electrolysis of water when wind conditions are good and release the stored hydrog en to supply the fuelcell when wind is low.

• 한국수소및신에너지학회논문집
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• 제34권4호
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• pp.342-349
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• 2023

In this study, a numerical simulations were conducted to analyze the phase change behavior of a liquid hydrogen storage container. The effects of gravity direction and hydrogen filling rate on boil-off gas (BOG) in the storage container were investigated. The study employed the volume of fluid, which is the phase change analysis model provided by ANSYS Fluent (ANSYS, Canonsburg, PA, USA), to investigate the sloshing phenomenon inside the liquefied hydrogen fuel tank. Considering the transient analysis time, two-dimensional simulation were carried out to examine the characteristics of the flow and thermal fields. The results indicated that the thermal flow characteristics and BOG phenomena inside the two-dimensional liquefied hydrogen storage container were significantly influenced by changes in gravity direction and hydrogen filling rate.

• 한국수소및신에너지학회논문집
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• 제27권6호
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• pp.642-650
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• 2016

One of the most feasible solution for reducing the excessive energy consumption and carbon dioxide emission is usage of more efficient fuel such as hydrogen. As is well known, there are three viable technologies for storing hydrogen fuel: compressed gas, metal hydride absorption, and cryogenic liquid. In these technologies, the storage for liquid hydrogen has better energy density by weight than other storage methods. However, the cryogenic liquid storage has a significant disadvantage of boiling losses. That is, high performance of thermal insulation systems must be studied for reducing the boiling losses. This paper presents an experimental study on the effective thermal conductivities of the composite layered insulation with aerogel blankets($Cryogel^{(R)}$ Z and $Pyrogel^{(R)}$ XT-E) and Multi-layer insulation(MLI). The aerogel blankets are known as high porous materials and the good insulators within a soft vacuum range($10^{-3}{\sim}1$ Torr). Also, MLI is known as the best insulator within a high vacuum range(<$10^{-6}{\sim}10^{-3}$ Torr). A vertical axial cryogenic experimental apparatus was designed to investigate the thermal performance of the composite layered insulators under cryogenic conditions as well as consist of a cold mass tank, a heat absorber, annular vacuum space, and an insulators space. The composite insulators were laminated in the insulator space that height was 50 mm. In this study, the effective thermal conductivities of the materials were evaluated by measuring boil-off rate of liquid nitrogen and liquid argon in the cold mass tank.

• 대한기계학회논문집B
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• 제32권1호
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• pp.54-61
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• 2008

Integrated Gasification Combined Cycle (IGCC) power plant converts coal to syngas, which is mainly composed of hydrogen and carbon monoxide, by the gasification process and produces electric power by the gas and steam turbine combined cycle power plant. The purpose of this study is to investigate the influence of using syngas in a gas turbine, originally designed for natural gas fuel, on its performance. A commercial gas turbine is selected and variations of its performance characteristics due to adopting syngas is analyzed by simulating off-design gas turbine operation. Since the heating value of the syngas is lower, compared to natural gas, IGCC plants require much larger fuel flow rate. This increases the gas flow rate to the turbine and the pressure ratio, leading to far larger power output and higher thermal efficiency. Examination of using two different syngases reveals that the gas turbine performance varies much with the fuel composition.

• 한국수소및신에너지학회논문집
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• 제20권5호
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• pp.384-389
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• 2009

KEPRI (Korea Electric Power Research Institute) has studied planar type solid oxide fuel cell (SOFC) stacks using anode-supported cells and kW class co-generation systems for residential power generation. In this work, a 1 kW SOFC system consisted of a hot box part, a cold BOP (balance of plant) part, and a hot water reservoir. The hot box part contained a SOFC stack made up of 48 cells, a fuel reformer, a catalytic combustor, and heat exchangers. Thermal management and insulation system were especially designed for self-sustainable operation in that system. A cold BOP part was composed of blowers, pumps, a water trap, and system control units. When the 1 kW SOFC stack was tested using hydrogen at $750^{\circ}C$, the stack power was about $1.2\;kW_e$ at 30 A and $1.6\;kW_e$ at 50 A. Turning off an electric furnace, the SOFC system was operated using hydrogen and city gas without any external heat source. Under self-sustainable operation conditions, the stack power was about $1.3\;kW_e$ with hydrogen and $1.2\;kW_e$ with city gas respectively. The system also recuperated heat of about $1.1\;kW_{th}$ by making hot water.

• 한국수소및신에너지학회논문집
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• 제24권2호
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• pp.113-120
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• 2013

A steam reformer is a chemical reactor to produce high purity hydrogen from fossil fuel. In the steam reformer, since endothermic steam reforming is heated by exothermic combustion of fossil fuel, the heat transfer between two reaction zones dominates conversion of fossil fuel to hydrogen. Steam Reforming is complex chemical reaction, mass and heat transfer due to the exothermic methane/air combustion reaction and the endothermic steam reforming reaction. Typically, a steam reformer employs burner to supply appropriate heat for endothermic steam reforming reaction which reduces system efficiency. In this study, the heat of steam reforming reaction is provided by anode-off gas combustion of stationary fuel cell. This paper presents a optimization of heat transfer effect and average temperature of cross-section using two-dimensional models of a coaxial cylindrical reactor, and analysis three-dimensional models of a coaxial cylindrical steam reformer with chemical reaction. Numerical analysis needs to dominant chemical reaction that are assumed as a Steam Reforming (SR) reaction, a Water-Gas Shift (WGS) reaction, and a Direct Steam Reforming(DSR) reaction. The major parameters of analysis are temperature, fuel conversion and heat flux in the coaxial reactor.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.353-356
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• 2009

A pivotal mechanical balance of plant for 75kW class molten carbonate fuel cells comprise of a catalytic burner and an ejector which has been designed and tested in KEPRI(Korea Electric Power Research Institute). The catalytic burner, which oxidizes residual fuel in the anode tail gas, was operated at several conditions. Some problems arose due to local overheating or auto-ignition, which could limit the catalyst life. The catalytic burner was designed by considering both gas mixing and gas velocity. Test results showed that the temperature distribution is very uniform. In addition, an ejector is a fluid machinery to be utilized for mixing fluids, maintaining vacuum, and transporting them. The ejector is placed at mixing point between the anode off gas and the cathode off gas or the fresh air Several ejectors were designed and tested to form a suction on the fuel tail gas and balance the differential pressures between anode and cathode over a range of operating conditions. The tests showed that the design of the nozzle and throat played an important role in balancing the anode tail and cathode inlet gas pressures. The 75kW MCFC system built in our ejector and catalytic burner was successfully operated from Novembe, 2008 to April, 2009. It recorded the voltage of 104V at the current of 754A and reached the maximum generating power of 78.5kW DC. The results for both stand-alone and integration into another balance of plant are discussed.

• 한국가스학회지
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• 제22권1호
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• pp.1-8
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• 2018

수소연료전지 자동차 압력 용기에는 연료전지 스택으로 수소의 흐름을 제어하기 위해 전자 밸브가 부착되고 있다. 전자 밸브의 솔레노이드는 전기 신호에 의해 유로를 개폐하는 역할을 하며, 전원이 인가되는 시간이 경과함에 따라 온도가 상승하여 일정 온도에서 포화된다. 특히 온도의 상승은 솔레노이드의 흡인력을 감소시키므로 안정적인 수소 공급을 위해서 설계 시 포화 온도와 온도에 따른 흡인력 특성 파악이 요구된다. 본 연구에서는 솔레노이드 설계 변수에 따른 포화 온도 계산식을 제안하고 열 유동 해석을 통해 타당성을 확인하였다. 또한, 온도에 따른 흡인력 변화를 분석하기 위해 전자기장 해석을 수행하였으며 온도 특성 실험을 통해 포화 온도와 흡인력 해석 결과를 검증하였다. 포화온도는 계산식과 해석결과를 비교하였을 때 $5.3^{\circ}C$, 해석 결과와 실험 결과를 비교하였을 때 $5.9^{\circ}C$의 오차가 발생하였으며, 흡인력은 1.0 N, 최대 2.1 N의 오차가 발생하였다.

• 해양환경안전학회지
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• 제28권2호
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• pp.361-369
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• 2022

강화되는 환경규제에 대응하기 위해서 세계 각국이 수소 경제로의 전환을 본격화하고 있으며, 이에 중장기적으로 수소의 국가간 물동량도 증가할 것으로 예상된다. 국가간 수소의 거래는 수출국의 신재생 에너지 자원과 수입국의 수소 사용 형태, 기술 성숙도 등을 고려하여 암모니아, 액화수소, LOHC 등의 형태로 이루어질 것이나, 어느 한 가지 형태로만 거래되지는 않을 것이다. 액화수소 대비 암모니아와 LOHC의 해상운송은 상대적으로 성숙한 기술임에 본 글에서는 향후 액화수소 운반선 개발을 위하여 필요한 세부 기술들의 식별 및 다양한 기술적 대안들을 통해 가능한 설계안을 확보하면서, 그에 따른 기술적 타당성을 분석하였다.

• 한국가스학회지
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• 제26권5호
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• pp.49-57
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• 2022

미래에 수소 산업이 활성화되면 LH2 멤브레인 저장탱크 인수기지는 대용량 액화수소를 저장하고 송출할 수 있는 주요한 방안이다. 현재 이러한 인수기지가 존재하지 않기에, 기존 LNG 멤브레인 저장탱크 인수기지 설계 자료를 참고하여 기지 공정모사 모델을 완성하였다. 이 모델을 베이스로 하여 멤브레인 저장탱크 인수기지 운영에서 매우 주요한 인자인 기지 설계조건 변화에 따른 BOG 발생량을 예측하였다. 이를 통하여 LH2 멤브레인 저장탱크 인수기지가 운영될 때를 대비하여 하역시 BOG 발생량을 최소화 할 수 있는 적절한 운전조건을 검토하고자 하였다.