• 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.

• 한국자동차공학회논문집
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• 제21권2호
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• pp.146-153
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• 2013

CNG buses has contributed to improve air quality in cities. But it is difficult to meet the next emission regulations such as EURO-VI without the help of additional post-processing device. Hydorgen has higher flame speed and lower combustion temperature that make it thermal efficiency increase with leaner operation. Using hydrogen natural gas blend (HCNG) fuel is promising technology which can reduce $NO_x$ and $CO_2$ emissions for a natural gas vehicle. However, fuel flow rate of HCNG should be increased since hydrogen's energy density per volume is much smaller than natural gas. In the present study, the characteristics of fuel supply system and its applicability were evaluated in a heavy duty natural gas engine. The results showed that the potential of fuel pressure regulator and fuel metering valve had enough capacity with HCNG. Employed mixer did not affect the distribution characteristics of mixture.

• 한국수소및신에너지학회논문집
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• 제12권3호
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• pp.211-217
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• 2001

From wood to coal and petroleum, mankind has used various fuel. Since using such fuel, mankind has developed power source of mechanism. We obtain numerous power from caloric force. Present energy supply is based on the fossil fuel. Fossil fuel has high energy density and is convenient for transportation and storage. Human being prepared countermeasure of energy economy, high energy efficiency and substitution energy for limits of fossil fuel. High energy efficiency among them is very important. This research will improve total output by physical exergy recovery of $LH_2$-fuel cell system.

• Korean Chemical Engineering Research
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• 제54권1호
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• pp.11-15
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• 2016

무인항공기가 장시간 비행하기 위해서는 배터리보다 고분자전해질 연료전지(PEMFC)가 적합하다. 본 연구에서는 PEMFC에 수소를 공급하는 $NaBH_4$가수분해 반응 시스템에 대해 연구하였다. $NaBH_4$가수분해 반응 시스템의 무게를 감소시키기 위해 수소수율 향상, 응축수 회수, 안정적인 수율 유지 등에 대해 실험하였다. 반응기 압력제어를 함으로써 수소 수율을 3.4% 향상시켰다. 수소를 공랭하여 PEMFC 스택에 공급하는 과정에서 발생하는 응축수를 $NaBH_4$ 저장조에 회수하였다. 이 과정에서 응축수가 $NaBH_4$분말을 용해시켜 보충됨으로써 14%의 무게 감량효과가 있었다. 2.0 L/min의 속도로 수소를 발생시킬 때 Co-P-B촉매 2.0 g을 사용해서 10시간동안 96% 수소수율로 $NaBH_4$가수분해 반응 시스템을 안정적으로 구동하였다.

• 한국초전도ㆍ저온공학회논문지
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• 제24권3호
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• pp.62-67
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• 2022

Liquid hydrogen (LH₂) has a higher density than gaseous hydrogen, so it has high transport efficiency and can be stored at relatively low pressure. In order to use efficient bulk hydrogen in the industry, research for the LH₂ supply system is needed. In the high-pressure hydrogen station based on LH₂ currently being developed in Korea, a heat exchanger is used to heat up supercritical hydrogen at 700 bar and 60 K, which is pressurized by a cryogenic high-pressure pump, to gas hydrogen at 700 bar and 300 K. Accordingly, the heat exchanger used in the hydrogen station should consider the design of high-pressure tubes, miniaturization, and freezing prevention. A helical heat exchanger generates secondary flow due to the curvature characteristics of a curved tube and can be miniaturized compared to a straight one on the same heat transfer length. This paper evaluates the heat transfer performance through parametric study on the distance between coils, guide effect, and anti-icing design of helical heat exchanger. The helical heat exchanger has better heat transfer performance than the straight tube exchanger due to the influence of the secondary flow. When the distance between the coils is uniform, the heat transfer is enhanced. The guide between coils increases the heat transfer performance by increasing the heat transfer length of the shell side fluid. The freezing is observed around the inlet of distribution tube wall, and to solve this problem, an anti-icing structure and a modified operating condition are suggested.

• 한국수소및신에너지학회논문집
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• 제30권4호
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• pp.347-355
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• 2019

As a solution to the growing concern on the global warming, researches are being actively carried out to apply carbon dioxide capture and storage technology to power generation systems. In this study, the integrated gasification combined cycle (IGCC) adopting oxy-combustion carbon capture was modeled and the effect of replacing the conventional air separation unit (ASU) with the ion transport membrane (ITM) on the net system efficiency was analyzed. The ITM-based system was predicted to consume less net auxiliary power owing to an additional nitrogen expander. Even with a regular pressure ratio which is 21, the ITM-based system would provide a higher net efficiency than the optimized ASU-based system which should be designed with a very high pressure ratio around 90. The optimal net efficiency of the ITM-based system is more than 3% higher than that of the ASU-based system. The influence of the operating pressure and temperature of the ITM on system efficiency was predicted to be marginal.

• 한국수소및신에너지학회논문집
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• 제20권2호
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• pp.104-115
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• 2009

In case of residential fuel cell system, it is significant to stably supply heat and power to a house with high efficiency and low cost for the successful commercialization. In this paper, the control strategy analysis has been performed to minimize the total cost including capital and operating cost of the residential fuel cell system. The proposed analysis methodology is based on the simulator including the efficiency models as well as the cost data for fuel cell components. The load control strategy is the key factor to decide the system efficiency and thus the cost analysis is performed when the fuel cell system is operated for several different load control logics. Additionally, annual efficiency of the system based on the seasonal load data is calculated since system efficiency is changeable according to the electric and heat demand change. As a result, the hybrid load control combined electricity oriented control and heat oriented control has the most economical operation.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2928-2933
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• 2008

Trends of the automotive market require the application of new engine technologies, which allows for the use of different types of fuel. Since ethanol is a renewable source of energy and it contributes to lower $CO_2$ emissions, ethanol produced from biomass is expected to increase in use as an alternative fuel. It is recognized that for spark ignition (SI) engines ethanol has advantages of high octane number and high combustion speed. In spite of the advantages of ethanol, fuel supply system might be affected by fuel blends with ethanol like a wear and corrosion of electric fuel pumps. So the on-board hydrogen production out of ethanol reforming can be considered as an alternative plan. This paper investigates the influence of ethanol fuel on SI engine performance, thermal efficiency and emissions. The combustion characteristics with hydrogen-enriched gaseous fuel from ethanol reforming are also examined.

• Korean Chemical Engineering Research
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• 제44권6호
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• pp.563-571
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• 2006

스테인리스 스틸 메쉬 표면을 환원 전처리하여 그 표면상에 직접 탄소나노튜브 또는 탄소나노섬유와 같은 VGCF (vapor grown carbon fiber) 나노물질을 합성 성장시켰다. 수소 가스를 이용하여 스테인리스 스틸 메쉬를 환원 처리함으로써, 금속 표면상에 bi-modal 분포의 작은 촉매입자와 큰 촉매입자들이 함께 생성되었다. 환원된 스테인리스 스틸 메쉬로부터 VGCF의 합성 시, 수소 가스가 공급되지 않은 경우는 작은 촉매입자로부터 탄소나노튜브들이 주로 성장되었으나, 특정 량의 수소 가스가 공급될 경우 큰 촉매입자로부터 탄소나노섬유들이 주로 성장되었다.

• Nuclear Engineering and Technology
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• 제45권3호
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• pp.401-414
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• 2013

HTR50S is a small modular reactor system based on HTGR. It is designed for a triad of applications to be implemented in successive stages. In the first stage, a base plant for heat and power is constructed of the fuel proven in JAEA's $950^{\circ}C$, 30MWt test reactor HTTR and a conventional steam turbine to minimize development risk. While the outlet temperature is lowered to $750^{\circ}C$ for the steam turbine, thermal power is raised to 50MWt by enabling 40% greater power density in 20% taller core than the HTTR. However the fuel temperature limit and reactor pressure vessel diameter are kept. In second stage, a new fuel that is currently under development at JAEA will allow the core outlet temperature to be raised to $900^{\circ}C$ for the purpose of demonstrating more efficient gas turbine power generation and high temperature heat supply. The third stage adds a demonstration of nuclear-heated hydrogen production by a thermochemical process. A licensing approach to coupling high temperature industrial process to nuclear reactor will be developed. The low initial risk and the high longer-term potential for performance expansion attract development of the HTR50S as a multipurpose industrial or distributed energy source.