• 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.

• 신재생에너지
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• 제7권3호
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• pp.59-66
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• 2011

Recently, an UAV using green energy for propulsion has been developed due to exhaustion of fossil fuel. This aircraft runs on electric motors rather than internal combustion engines, with electricity coming from fuel cells, solar cells, ultracapacitors, and/or batteries. Especially solar cells are installed in HALE UAV and flight tests are performed in the stratosphere. Although the solar powered UAV has the advantage of zero emission, its energy conversion efficiency is low and operation time is limited. Therefore, the solar powered UAV has been designed to operate with the secondary battery obtaining flexibility of energy management. In this study, we suggest the new operational concept of the solar powered UAV using directed-energy rayed from the surface of earth to UAV. An UAV is able to secure additional power through attaching solar cell to the lower surface of elevator. As a result, the additional energy supplied by directed-energy can improve the energy management and operational flexibility of the solar powered UAV.

• 한국수소및신에너지학회논문집
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• 제23권3호
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• pp.243-249
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• 2012

A lightweight 200W direct methanol fuel cell (DMFC) stack is designed and fabricated to power a small scale Unmanned Aerial Vehicle (UAV). The DMFC stack consists of 33-cells in which membrane-electrode assemblies (MEAs) having an active area of 88 $cm^2$ are sandwiched with lightweight composite bipolar plates. The total stack weight is around 3.485 kg and stack performance is tested under various methanol feed concentrations. The DMFC stack delivers a maximum power of 248 W at 13.2 V and $71.3^{\circ}C$ under methanol feed concentration of 1.2 M. In addition, the voltage of individual cell in the 33-cell stack is measured at various current levels to ensure the stability of DMFC stack operations. The cell voltage distribution data exhibit the maximum cell voltage deviation of 28 mV at 15 A and hence the uniformity of cell voltages is acceptable. These results clearly demonstrate that DMFC technology becomes a potential candidate for small-scale UAV applications.

• Advances in aircraft and spacecraft science
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• 제9권1호
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• pp.17-37
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• 2022

This paper discusses an improved unmanned aerial vehicle, UAV, configuration characterized by telescopic booms to optimize the flight mechanics and fuel consumption of the aircraft at various loading/flight conditions.The starting point consists of a full-composite smaller UAV which was derived by a general aviation ultralight motorized aircraft ULM. The present design, named ToBoFlex, extends the two-booms configuration to a three tons aircraft. To adapt the design to needs relevant to different applications, new solutions were proposed in aerodynamic fields and materials and structural areas. Different structural solutions were reported. To optimize aircraft endurance, the innovative concept of Telescopic Tail Boom was considered along with two different tails architecture. A new structural configuration of the fuselage was proposed. Further consideration of hydrogen fuel cell electric propulsion is now being studied in collaboration between the Polytechnic of Turin and Prince Mohammad Bin Fahd University which could be the starting point of future investigations.

• 한국수소및신에너지학회논문집
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• 제27권1호
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• pp.42-48
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• 2016

This study presents an experiment investigation on natural convection heat transfer of air-cooling Proton exchange membrane fuel cells (PEMFCs) in a enclosure system for unmanned aerial vehicles (UAVs). Considered are replacing fuel cell stack with Aluminum block for heat generating inside a enclosure chamber. The volume ratio of fuel cell stack and chamber for simulation to the actual size of aerial vehicle is 1 to 15. The parameters considered for experimental study are the environmental temperature range from $25^{\circ}C$ to $-60^{\circ}C$ and the block heat input of 10 W, 20 W and 30 W. Effect of the thermal conductivity of the block and power level on heat transfer in the chamber are investigated. Experimental results illustrate the temperature rise at various locations inside the chamber as dependent upon heat input of fuel cell stack and environmental temperature. From the results, dimensionless correlation in natural convection was proposed with Nusselt number and Rayleigh number for designing air-cooling PEMFC powered high altitude long endurance (HALE) UAV.

• 한국수소및신에너지학회논문집
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• 제22권6호
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• pp.819-826
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• 2011

The proton exchange membrane fuel cell (PEMFC) is regarded as the most promising alternative power sources for unmanned aerial vehicle (UAV) due to its high energy density and silent operation. Since there are many load changes during UAV flight, thermal management is one of the important factor for the performance of PEMFC. In order to reduce the UAV weight for the stable operation of UAV, thermal management system (TMS) studied in this work does not use the fan but use the air flowing into UAV by UAV flight. In order to develop the passive type heat exchanger (HEX) for 1kW PEMFC, four types of HEXs are fabricated and their cooling performances are compared. The parametric study on the cooling performance of HEXs has performed with the variation of operating parameters such as mass flow rates and inlet temperature of air and coolant. Type 4 has the best performance in every case. This study can be helpful to achieve the optimal design of HEX for PEMFC powered UAV.

• 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.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2009년도 제33회 추계학술대회논문집
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• pp.278-281
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• 2009

소형 정찰 UAV의 새로운 동력원으로 적용하고자 하는 연료전지 시스템의 경량화를 위한 연구로 알루미늄 분리판의 성능을 측정하였다. 흑연 분리판과의 성능 비교를 통해 알루미늄 분리판이 흑연 분리판에 비해 무게 대비 높은 성능을 보이는 것을 확인하였다. 작동온도에 따른 성능 변화를 확인하기 위해 40 / 50 / $60^{\circ}C$의 작동온도에서 알루미늄 단위 전지의 성능을 측정한 결과 건조한 반응기체의 경우 일반적인 작동온도 보다 비교적 낮은 $40^{\circ}C$에서 가장 좋은 성능을 보이는 것을 확인하였다.

• 한국수소및신에너지학회논문집
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• 제25권4호
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• pp.393-404
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• 2014

Unmanned aerial vehicles (UAVs) have been applied to not only military missions like surveillance and reconnaissance but also commercial missions like meteorological observation, aerial photograph, communication relay, internet network build and disaster observation. Fuel cells make UAVs eco-friendly by using hydrogen. Proton exchange membrane fuel cells (PEMFCs) show low operation temperature, high efficiency, low noise and high energy density and those characterisitcs are well fitted with UAVs. Thus Fuel cell based UAVs have been actively developed in the world. Recently, fuel cell UAVs have started to develope for high altitude UAVs because target altitude of UAVs is expanded upto stratosphere altitude. Long endurance of UAVs is essential to improve effects of the missions. Improvement of UAV endurance time could be fulfilled by developing a hydrogen fuel storage system with high energy density and reducing the weight of UAVs. In this paper, research trend and analysis of fuel cell UAVs are introduced in terms of their altitude and endurance time and then the prospect of fuel cell UAVs are shown.

• 항공우주산업기술동향
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• 제7권2호
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• pp.95-105
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• 2009

연료전지는 소음이 낮고$CO_2$ 배출이 없는 친환경적 특성을 기반으로 항공기 추진시스템에 적용되고 있으며, 현재 연료전지를 탑재한 여러 종류의 무인항공기와 소형 유인항공기 개발이 진행되고 있다. 항공기용 연료전지는 대표적으로 PEMFC(Proton Exchange Membrane Fuel Cell)방식과 SOFC(Solid Oxide Fuel Cell) 방식으로 분류되며, 항공기의 임무 및 운용조건에 적합한 연료전지 시스템이 개발되고 있다. 무인항공기의 경우 대부분 PEM 연료전지 기술을 기반으로 군용 또는 상용으로 활용할 수 있는 다양한 형태와 크기의 항공기가 개발되고 있으며, 시스템의 안정성과 운용시간이 더욱 향상될 것이다. 소형 유인항공기에서는 추진시스템을 연료전지로 대체하기 위한 많은 연구가 수행되고 있으며, 또한 대형 상용 항공기의 보조동력장치(APU)에 연료전지를 적용하여 성능을 높이기 위한 개발이 진행되고 있다. 향후, 연료전지항공기는 연료전지의 전력밀도 증가와 더불어 신뢰성과 효율을 더욱 향상시킬 것으로 기대된다.