• Title/Summary/Keyword: high energy density fuel

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Optimal Design of RSOFC System Coupled with Waste Steam Using Ejector for Fuel Recirculation (연료 재순환 이젝터를 이용한 연료전지-폐기물 기반 가역 고체 산화물 연료전지의 최적 설계)

  • GIAP, VAN-TIEN;LEE, YOUNG DUK;KIM, YOUNG SANG;QUACH, THAI QUYEN;AHN, KOOK YOUNG
    • Transactions of the Korean hydrogen and new energy society
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    • v.30 no.4
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    • pp.303-311
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    • 2019
  • Reversible solid oxide fuel cell (RSOFC) has become a prospective device for energy storage and hydrogen production. Many studies have been conducted around the world focusing on system efficiency improvement and realization. The system should have not only high efficiency but also a certain level of simplicity for stable operation. External waste steam utilization was proved to remarkably increase the efficiency at solid oxide electrolysis system. In this study, RSOFC system coupled with waste steam was proposed and optimized in term of simplicity and efficiency. Ejector for fuel recirculation is selected due to its simple design and high stability. Three system configurations using ejector for fuel recirculation were investigated for performance of design condition. In parametric study, the system efficiencies at different current density were analyzed. The system configurations were simulated using validated lumped model in EBSILON(R) program. The system components, balance of plants, were designed to work in both electrolysis and fuel cell modes, and their off-design characteristics were taken into account. The base case calculation shows that, the system with suction pump results in slightly lower efficiency but stack can be operated more stable with same inlet pressure of fuel and air electrode.

Power Management of Fuel Cell Propulsion System for Unmanned Aerial Vehicles (무인기용 연료전지 추진 시스템의 동력 관리)

  • Kim, Tae-Gyu;Shim, Hyun-Chul;Kwon, Se-Jin
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2007.11a
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    • pp.13-16
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    • 2007
  • Fuel cell was used as a propulsion system for unmanned aerial vehicles (UAV) in the present study. Fuel cell propulsion system are an ideal alternative power source with high energy density for high-endurance UAV. Fuel cell power system provides UAV up to five times the energy densiη of existing batteries. Sodium borohydride, stored in liquid state, was selected as a hydrogen source. Hydrogen generation system consists of catalytic reactor, pump, fuel cartridge, and separator. Hybrid power management system (PMS) between fuel cell and lithium-polymer ba야ery was developed. Motor, pump, and fans, operated on battery power controlled by feedback signals of fuel cell system. Battery was recharged by surpuls powr of fuel cell.

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Analysis of Thermal Effect by Coolant Plate Number in High-Temperature Polymer Electrolyte Membrane Fuel Cell Stack (고온형 고분자 전해질 연료전지 스택 내부의 냉각판 수가 스택에 미치는 열 영향성의 수치적 연구)

  • Choi, Byung Wook;Ju, Hyun Chul
    • Transactions of the Korean hydrogen and new energy society
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    • v.26 no.2
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    • pp.127-135
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    • 2015
  • High-Temperautre Polymer Electrolyte Membrane Fuel Cell (HT-PEMFC) with phosphoric acid-doped polybenzimidazole (PBI) membrane has high power density because of high operating temperature from 100 to $200^{\circ}C$. In fuel cell stack, heat is generated by electrochemical reaction and high operating temperature makes a lot of heat. This heat is caouse of durability and performance decrease about stack. For these reasons, heat management is important in HT-PEMFC. So, we developed HT-PEMFC model and study heat flow in HT-PEMFC stack. In this study, we placed coolant plate number per cell number ratio as variable and analysed heat flow distribution in stack.

High Efficiency DC-DC Converter for Fuel Cell System (연료전지 계통 연계형 고효율 DC-DC 컨버터)

  • Oh, Eun-Tae;Yoon, Soo-Young;Lee, Yoon-Jae;You, Gwang-Min;Chae, Hyung-Jun;Han, Byung-Moon;Lee, Jun-Young
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.12
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    • pp.2410-2415
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    • 2009
  • Studying for environmental friendly and efficient energy source is now actively under way on because problems like environmental pollution and exhaust of natural resources are in issue. Fuel Cell which is an alternative energy source has low voltage and high current characteristic, therefore boost up voltage converter and DC-AC converter is required to use as a common power source. In this paper, DC-DC converter which has high efficient and high power density is proposed and verified by experimental result.

SIMULATION OF UNIT CELL PERFORMANCE IN THE POLYMER ELECTROLYTE MEMBRANE FUEL CELL

  • Kim, H.G.;Kim, Y.S.;Shu, Z.
    • International Journal of Automotive Technology
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    • v.7 no.7
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    • pp.867-872
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    • 2006
  • Fuel cells are devices that convert chemical energy directly into electrical energy. Owing to the high efficiency of the fuel cells, a large number of research work have been done during these years. Among many kinds of the fuel cells, a polymer electrolyte membrane fuel cell is such kind of thing which works under low temperature. Because of the specialty, it stimulated intense global R&D competition. Most of the major world automakers are racing to develop polymer electrolyte membrane fuel cell passenger vehicles. Unfortunately, there are still many problems to be solved in order to make them into the commercial use, such as the thermal and water management in working process of PEMFCs. To solve the difficulites facing the researcher, the analysis of the inner mechanism of PEMFC should be implemented as much as possible and mathematical modeling is an important tool for the research of the fuel cell especially with the combination of experiment. By regarding some of the assumptions and simplifications, using the finite element technique, a two-dimensional electrochemical mode is presented in this paper for the further comparison with experimental data. Based on the principals of the problem, the equations of electronic charge conservation equation, gas-phase continuity equation, and mass balance equation are used in calculating. Finally, modeling results indicate some of the phenomenon in a unit cell, and the relationships between potential and current density.

Aeroassisted Orbital Maneuvering in a Worst-Case Atmosphere (최악의 대기 조건 하의 공기조력 비행선 운전)

  • Lee, Byoungsoo
    • Journal of Institute of Control, Robotics and Systems
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    • v.6 no.10
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    • pp.936-941
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    • 2000
  • Advanced space transportation systems, such as the National Aerospace Plane or an Orbital Transfer Vehicle, have atmospheric maneuvering capabilities. For such vehicles the use of aeroassisted orbital transfer from a high Earth orbit to a low Earth orbit, with unpowered flight in the atmosphere, has the potential for significant fuel savings compared to exoatmospheric Hohmann transfer. However, to exploit the fuel savings that can be achieved by using the Earths atmosphere to reduce the vehicles energy, a guidance law is required, and it must be able to handle large unpredictable fluctuations in atmospheric density, on the order of ${\pm}$50% relative to the 1962 US Standard Atmosphere. In this paper aeroassisted orbital transfer is considered as a differential game, with Nature controlling the atmosphere density to yield a worst case (min-max fuel required) atmosphere, from which the guaranteed playable set boundary are achieved. Inside the playable set, it is guaranteed that the vehicle achieves the optimal atmospheric exit condition for the minimum fuel consumption regardless of the atmospheric density variations.

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Characteristics of Pt-Ru Catalyst Supported on Activated Carbon for Direct Methanol Fuel Cell

  • Jung, Doo-Hwan;Jung, Jae-Hoon;Hong, Seong-Hwa;Peck, Dong-Hyun;Shin, Dong-Ryul;Kim, Eui-sik
    • Carbon letters
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    • v.4 no.3
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    • pp.121-125
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    • 2003
  • The Pt-Ru/Carbon as an anode catalyst supported on the commercial activated carbon (AC) having high surface area and micropore was characterized for application of Direct Methanol Fuel Cell (DMFC). The Pt-Ru/AC anode catalyst used in this experiment showed the performance of $600\;mA/cm^2$ current density at 0.3 V. The borohydride reduction process using $NaBH_4$, denoted as a process A, showed much higher current and power densities than process B prepared by changing the reduction and washing process of process A. The particle sizes are strongly affected by the reduction process than the specific surface area of raw active carbon and the sizes are almost constant when the specific surface area of carbon are over than the $1200\;m^2/g$. Smaller particle size of catalyst and more narrow intercrystalite distance increased the performance of DMFC.

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THE IMPACT OF FUEL CYCLE OPTIONS ON THE SPACE REQUIREMENTS OF A HLW REPOSITORY

  • Kawata, Tomio
    • Nuclear Engineering and Technology
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    • v.39 no.6
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    • pp.683-690
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    • 2007
  • Because of increasing concerns regarding global warming and the longevity of oil and gas reserves, the importance of nuclear energy as a major source of sustainable energy is gaining recognition worldwide. To make nuclear energy truly sustainable, it is necessary to ensure not only the sustainability of the fuel supply but also the sustained availability of waste repositories, especially those for high-level radioactive waste (HLW). From this perspective, the effort to maximize the waste loading density in a given repository is important for easing repository capacity problems. In most cases, the loading of a repository is controlled by the decay heat of the emplaced waste. In this paper, a comparison of the decay heat characteristics of HLW is made among the various fuel cycle options. It is suggested that, for a future fast breeder reactor (FBR) cycle, the removal and burning of minor actinides (MA) would significantly reduce the heat load in waste and would allow for a reduction of repository size by half.

Prospect and Technical Challenges for Portable Fuel Cell Commercialization

  • Lee, Seung-Jae
    • Proceedings of the Korea Society for Energy Engineering kosee Conference
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    • 2003.05a
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    • pp.191-209
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    • 2003
  • Voices of Customers; 1. Long time operating power 2. Quick Charging 3. High power and energy density 4. Safety 5. Small and light power Technical Requirements for Delivering DMFC to Consumer's Hands; 1. MEA having tripled power density. 2. Membrane of maintaining the same protonic conductivity and near 0% cross-over when 10M or higher concentration of methanol fueling (Omitted)

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A Study on Dispersed Media Formation of Hydrocarbon Fuel by an Explosive Burster (화약 폭발에 의한 탄화수소계 연료의 분산매질 형성에 관한 연구)

  • Yoo, Jae Hun
    • Journal of the Korean Society of Safety
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    • v.31 no.2
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    • pp.33-40
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    • 2016
  • Liquid fuel can be easily exploded and release more energy of detonation than conventional explosives because it has different explosion mechanism. In order to analyze dispersion characteristics of liquid fuel for the safety purpose, two tests are conducted. First, pre-test, which is a computer simulation, is carried out by a software called ANSYS AUTODYN to eliminate the effect of a canister that usually causes irregular dispersion of the fuel. Second, field test is performed to find out the amount and density effect of bursting charge. High speed cameras are installed in front of the canister to visualize the mechanism. Velocity, area and radius of the dispersed cloud are measured by image processing software, these are shown that the amount of bursting charge affects cloud velocity and area but density is not a significant factor of cloud formation.