• International Journal of Aerospace System Engineering
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• 제4권2호
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• pp.5-9
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• 2017

In a pressurized fuel supply system of aircraft, a flow passage opening device is required to keep fuel continuously transferred from one tank to the other. The device utilizes balancing weights in order to follow up an acceleration at special conditions such as negative g. It is very difficult to test the device in a real high-speed and high-altitude test since severe test conditions and expensive supports are needed. Therefore, this paper deals with performance analysis of a flow passage opening device through low speed aircraft captive flight tests (CFT) including roll and negative-g maneuvers. It is shown that balancing weights in the device can open the passage in accordance with fuel position.

• 설비공학논문집
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• 제16권7호
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• pp.615-622
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• 2004

Recently, the hybrid system combining fuel cell and gas turbine has drawn much attention owing to its high efficiency and ultra low emission. It is now on the verge of world wide development and various system configurations have been proposed. A national project funded by Korean government has also been initiated to develop a pressurized hybrid system. This work aims at presenting design performance analysis for various possible system configurations as an initial step for the system development. Study focuses are given to major design options including the power ratio between gas turbine and fuel cell, reforming method (internal or external), reforming heat source (reforming burner, cathode hot air, fuel cell heat release) and steam supply method for reformer (anode gas recirculation, external steam generator). A wide variation in performance among different configurations has been predicted.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2012년도 제38회 춘계학술대회논문집
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• pp.149-152
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• 2012

본 논문은 연료전지 UAV의 친환경 추진 시스템을 위한 통합형 수소 공급 시스템 연구에 대해 기술하고 있다. 고체 상태 $NaBH_4$를 직접 분해하기 위해 희석된 염산을 사용하였다. 안정적인 수소 공급을 위해 자체 수소 가압형 반응기와 압력 레귤레이터를 적용하였다. 컨셉 실증과 성능 검증을 위해 고체 상태 $NaBH_4$를 직접 분해하는 통합형 수소 공급 시스템의 시제품을 설계하였다.

• 설비공학논문집
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• 제16권11호
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• pp.1013-1020
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• 2004

The hybrid system of gas turbine and fuel cell is expected to produce electricity more efficiently than conventional methods, especially in small power applications such as distributed generation. The solid oxide fuel cell (SOFC) is currently the most promising fuel cell for the hybrid system. To realize the conceptual advantages resulting from the hybridization of gas turbine and fuel cell, optimized construction of the whole system must be the most important. In this study, parametric design analyses for pressurized GT/SOFC systems have been peformed considering probable practical limiting design factors such as turbine inlet temperature, fuel cell operating temperature, temperature rise in the fuel cell and soon. Analyzed systems include various configurations depending on fuel reforming type and fuel supply method.

• 한국항공우주학회지
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• 제40권10호
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• pp.901-909
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• 2012

본 논문은 연료전지 UAV를 위한 고체 상태의 $NaBH_4$ 수소 발생 및 공급 시스템의 특성에 대해 기술하고 있다. 산을 이용하여 $NaBH_4$를 분해할 경우, 발생된 수소의 유량과 압력은 급격히 변화하게 된다. 공급 수소는 자체 가압식 반응기로 안정화 되었고, 수소의 안정화 방법에 대해 소개하였다. 영하조건에서 수소를 발생시키기 위해 묽은 염산을 프로필렌 글리콜 혼합 용액으로 희석하였다. 고체 상태 $NaBH_4$ 수소 발생 및 공급 시스템을 설계하였다. 수소 발생 시스템의 특성을 밝혀내기 위한 기본 구동 실험을 수행하였다.

• 한국수소및신에너지학회논문집
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• 제27권5호
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• pp.485-493
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• 2016

Recently submarine and unmanned underwater vehicle (UUV) are equipped with a fuel cell system as an air independent propulsion system. Methanol fuel processor can efficiently supply the hydrogen to the fuel cell system to improve the ability to dive. This study investigated the optimal conditions of the methanol fuel processor that may be used in the closed environment. For this purpose, the numerical model based on Gibbs minimization equation was established for steam reformer and three exhaust gas burners. After simulating the characteristics of steam reformer according to the steam-to-carbon ratio (SCR) and the pressure change, the SCR condition was able to narrow down to 1.1 to 1.5. Considering water consumption and the amount of heat recovered from three burners, the optimum condition of the SCR can be determined to be 1.5. Nevertheless, the additional heat supply is required to satisfy the heat balance of the methanol fuel processor in the SCR=1.5. In other to obtain additional amount of heat, the combustion of methanol is better than the increased of SCR in terms of system design.

• 한국수소및신에너지학회논문집
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• 제23권3호
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• pp.250-255
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• 2012

In this paper, the development and performance analysis of a fuel cell-powered unmanned aerial vehicle is described. A fuel cell system featuring 1 kW proton exchange membrane fuel cell combined with a highly pressurized fuel supply system is proposed. For the higher fuel consumption efficiency and simplification of overall system, dead-end type operation is chosen and each individual system such as purge system, fuel supply system, cooling system is developed. Considering that fluctuation of exterior load makes it hard to stabilize fuel cell performance, the power management system is designed using a fuel cell and lithium-ion battery hybrid system. After integration of individual system, the performance of unmanned aerial vehicle is analyzed using data from flight and laboratory test. In the result, overall system was properly operated but for more duration of flight, research on weight lighting and improvement of fuel efficiency is needed to be progressed.

• 한국추진공학회지
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• 제20권1호
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• pp.76-81
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• 2016

부력을 이용한 연료공급밸브는 고속 비행체의 가압식 연료탱크 내 연료가 역 중력 상태에서 한 방향으로 이동하는 것을 쫓아 유로를 열어주어 지속적으로 흐르게 한다. 가혹한 시험조건과 고비용 등의 문제로 이 연료공급밸브를 실제 고속으로 시험하는 것은 쉽지 않은 일이다. 따라서 본 연구는 고속 시험 전에 저속항공기에 탑재해 기본적인 회전기동 및 역중력 시험(Negative-g test)을 수행한 내용을 포함하고 있다. 시험 결과를 바탕으로 각 기동에서 밸브의 작동 특성을 파악하고 분석하였다.

• 한국군사과학기술학회지
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• 제20권4호
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• pp.528-535
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• 2017

Fuel cells have been spotlighted in the world for being highly efficient and environmentally friendly. A hydrogen which is the fuel of fuel cell can be obtained from a number of sources. Hydrogen source for operating the polymer electrolyte membrane fuel cell(PEMFC) in the current underwater environment, such as a submarine and unmanned underwater vehicles are currently from the metal hydride cylinder. However, metal hydride has many limitations for using hydrogen carrier, such as large volume, long charging time, limited storage capacity. To solve these problems, we suggest diesel reformer for hydrogen supply source. Diesel fuel has many advantages, such as high hydrogen storage density, easy to transport and also well-infra structure. However, conventional diesel reforming system for PEMFC requires a large volume and complex CO removal system for lowering the CO level to less than 10 ppm. In addition, because the preferential oxidation(PROX) reaction is the strong exothermic reaction, cooling load is required. By changing this PROX reactor to hydrogen separation membrane, the problem from PROX reactor can be solved. This is because hydrogen separation membranes are small and permeable to pure hydrogen. In this study, we conducted the pressurized diesel reforming and water-gas shift reaction experiment for the hydrogen separation membrane application. Then, the hydrogen permeation experiments were performed using a Pd alloy membrane for the reformate gas.

• Nuclear Engineering and Technology
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• 제49권5호
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• pp.979-988
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• 2017

The feasibility of cooling in a pressurized heavy water reactor after a large break loss-of-coolant accident has been analyzed using Multidimensional Analysis of Reactor Safety-KINS Standard code during the recirculation phase. Through evaluation of sensitivity of the fuel channel temperature to various effective recirculation flow areas, it is determined that proper cooling of the fuel channels in the broken loop is feasible if the effective flow area remains above approximately 70% of the nominal flow area. When the flow area is reduced by more than approximately 25% of the nominal value, however, incipience of boiling is expected, after which the thermal integrity of the fuel channel can be threatened. In addition, if a dramatic reduction of the recirculation flow occurs, excursions and frequent fluctuations of temperature in the fuel channels are likely to be unavoidable, and thus damage to the fuel channels would be anticipated. To resolve this, emergency coolant supply through the newly installed external injection path can be used as one alternative means of cooling, enabling fuel channel integrity to be maintained and permanently preventing severe accident conditions. Thus, the external injection flow required to guarantee fuel channel coolability has been estimated.