• Title/Summary/Keyword: Fuel film

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Applications to Thin Film Processing to Solid Oxide Fuel Cells

  • Kim, Eui-Hyun;Hwang, Hee-Su;Ko, Myeong-Hee;Hwang, Jin-Ha
    • Proceedings of the Korean Vacuum Society Conference
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    • 2013.02a
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    • pp.696-696
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    • 2013
  • Solid Oxide Fuel Cells (SOFCs) have been gaining academic/industrial attention due to the unique high efficiency and minimized pollution emission. SOFCs are an electrochemical system composed of dissimilar materials which operates at relatively high temperatures ranging from 800 to 1000oC. The cell performance is critically dependent on the inherent properties and integration processing of the constituents, a cathode, an electrolyte, an anode, and an interconnect in addition to the sealing materials. In particular, the gas transport, ion transport, and by-product removal also affect the cell performance, in terms of open cell voltages, and cell powers. In particular, the polarization of cathode materials is one of the main sources which affects the overall function in SOFCs. Up to now, there have been studies on the materials design and microstructure design of the component materials. The current work reports the effect of thin film processing on cathode polarization in solid oxide fuel cells. The polarization issues are discussed in terms of dc- and ac-based electrical characterizations. The potential of thin film processing to the applicability to SOFCs is discussed.

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A Study on the Fuel Injection System for Optimizing Reduction of HC Emission (HC저감용 최적 연료분사 시스템에 관한 연구)

  • Lee, K.H.;Lee, C.S.
    • Transactions of the Korean Society of Automotive Engineers
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    • v.3 no.2
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    • pp.146-156
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    • 1995
  • Growing international concern about environmental issues in recent years has led to new proposals for strengthening exhaust emission standards and fuel economy requirements throughout the world. The low emission vehicle(LEV) standards drawn up by the California Air Resources Board(CARB) in the U.S.A are noticeably stringent To cope with this regulation, a reduction of HC emission is the most important challenge for the automotive industry because HC emission levels are severer than any other components emission levels. In this paper, the apparatus for visulalizing the wall film flow in a intake manifold and the spark plug with optical fiber for detecting the signal from diffusion flame are developed to mal,e the HC formation mechanism clear. High speed camera system is also used to elucidate the correlation wall film flow and the diffusion flame. Using these methods, the effect of fuel injection systems such as injection direction, spray angle, atomised injection on HC emission levels is investigated. Consequently, the optimal fuel injection conditions for minimizing the wall film flow and reducing the HC emission are found through this research.

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A Numerical Study on the Combustion Characteristics in a Liquid Rocket Engine with Film Cooling Effect (막냉각 효과를 고려한 액체로켓 엔진의 연소 특성에 관한 연구)

  • Byeon,Do-Yeong;Kim,Man-Yeong;Baek,Seung-Uk
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.31 no.8
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    • pp.69-76
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    • 2003
  • For stable combustion and safety of a structure of the propulsion system, a cooling system to the liquid rocket engine should be incorporated. In this study, Eulerian-Lagrangian scheme for two phase combustion, nongray radiation and soot formation effect, and film-wall interaction have been introduced to study the effect of film cooling. After briefly introducing the governing equation, combustion characteristics with change of wall temperature has been investigated by varying such parameters as fuel mass fraction for film cooling, diameter of the fuel droplet, overall mixture fraction of oxygen to fuel. Also, radiative heat flux is compared with the conductive one at the combustor wall.

A Study on Homogeneous Mixture Supply in a Multi-Cylinder Spark Ignition Engine - Effect on Combustion Characteristics - (다기통 전기점화기관의 균질혼합기 공급에 관한 연구 - 연소특성에 미치는 영향 -)

  • 김물시;이용길;박경석
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.8
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    • pp.2194-2200
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    • 1994
  • In an automotive spark ignition engine, it is important to form the proper mixture (air/fuel) on each driving condition for developing the stabilizing combustion and exhaust characteristics. Since most of supply fuel si attached on the inside wall of the intake manifold for unadequate nonuniformity of fuel distribution to each cylinder and mixture variation. Also it affects engine performance variation and causes noises and vibration. In this study, we verified the effect of the mixture variation which is caused by fuel liquid film in the intake manifold on combustion characteristics and engine performance.

Initial Performance Degradation of Hydrogen-Fueled Ceramic Fuel Cell with Plasma-Enhanced Atomic Layer-Deposited Ultra-Thin Electrolyte (플라즈마 원자층증착 초박막전해질 수소 세라믹연료전지의 초기성능 저하)

  • JI, SANGHOON
    • Journal of Hydrogen and New Energy
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    • v.32 no.5
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    • pp.340-346
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    • 2021
  • The initial electrochemical performance of ceramic fuel cell with thin-film electrolyte fabricated by plasma-enhanced atomic layer deposition method was evaluated in terms of peak power density ratio, open circuit voltage ratio, and activation/ohmic resistance ratios at 500℃. Hydrogen and air were used as anode fuel and cathode fuel, respectively. The peak power density ratio reduced as ~52% for 30 min, which continually decreased as time increased but degradation rate gradually decreased. The open circuit voltage ratio decreased with respect time; however, its behavior was evidently different from the reduction behavior of the peak power density. The activation resistance ratio increased as ~127% for 30 min, which was almost similar with the reduction behavior of the peak power density ratio.

Preparation of Thin Film Electrolyte for Solid Oxide Fuel Cell by Sol-Gel Method and Its Gas Permeability (졸-겔법을 이용한 고체산화물연료전지의 전해질 박막 제조 및 가스 투과도)

  • Son, Hui-Jeong;Lee, Hye-Jong;Lim, Tak-Hyoung;Song, Rak-Hyun;Peck, Dong-Hyun;Shin, Dong-Ryul;Hyun, Sang-Hoon;Kilner, John
    • Journal of the Korean Ceramic Society
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    • v.42 no.12 s.283
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    • pp.827-832
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    • 2005
  • In this study, thin electrolyte layer was prepared by 8YSZ ($8mol\%$ Yttria-Stabilized Zirconia) slurry dip and sol coating onto the porous anode support in order to reduce ohmic resistance. 8YSZ polymeric sol was prepared from inorganic salt of nitrate and XRF results of xerogel powder exhibited similar results $(99.2\pm1wt\%)$ compared with standard sample (TZ-8YS, Tosoh Co.). The dense and thin YSZ film with $1{\mu}m$ thickness was synthesized by coating of 0.7M YSZ sol followed by heat-treatment at $600^{\circ}C$ for 1 h. Thin film electrolyte sintered at $1400^{\circ}C$ showed no gas leakage at the differential pressure condition of 3 atm.

A Study on the Optimum Clearance Selection of Fuel Pump Journal Bearing with Elasto-hydrodynamic Lubrication Analysis (탄성유체윤활해석에 의한 연료 펌프 저널베어링 최적간극 선정 연구)

  • An, Sung Chan;Lee, Sang Don;Son, Jung Ho;Cho, Yong Joo
    • Tribology and Lubricants
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    • v.33 no.1
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    • pp.23-30
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    • 2017
  • The electric controlled marine diesel engine has fuel pump generating the high pressurized fuel for fuel injection to combustion chamber via a common rail. Fuel pump consists of a cam-roller system. Journal bearing installed between a roller and a cam-roller pin is subjected to fluctuating heavy and instant loads by cam lift. First, Kinematic analysis is carried out to predict bearing loads during one cycle acting on the journal bearing. Second, flexible multi-body dynamic analysis and transient elasto-hydrodynamic(EHD) lubrication analysis for journal bearing considering elastic deformation of cam-roller pin, roller and bearing are conducted using AVL EXCITE/PU software to predict lubrication performance. The clearance ratio and journal groove shape providing lubrication oil are important parameter in bearing design having good performance and can be changed easier than other design parameters such as diameter, width, oil supply pressure and bearing material grade. Generally, journal bearing performance is represented by the minimum oil film thickness(MOFT) and peak oil film pressure(POFP). As well as the traditional design parameters(MOFT, POFP), in this study, temperature rise of lubrication oil is also evaluated through the side leakage flow of supplied oil. By the evaluating MOFT, POFP and temperature rise, the optimum bearing clearance ratio is decided.

The Initial Film Flow Development of the High-Pressure Swirl Spray (고압스월분무 액막유동의 초기 발달과정에 대한 연구)

  • Moon, Seok-Su;Abo-Serie, Essam;Choi, Jae-Joon;Bae, Choong-Sik
    • Journal of ILASS-Korea
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    • v.11 no.4
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    • pp.212-219
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    • 2006
  • The initial film flow development of the high-pressure swirl spray was investigated at different injector operating conditions to analyze film flow development and to provide the input data for the modeling works. This result can be also useful to verify the previously simulated results. The initial flow conditions such as liquid film thickness, flow angle and flow divergence are obtained by visualizing the inside and near the nozzle flow with a microscopic imaging system. The visualized images are quantified using an image processing tool. From the information of liquid film thickness and flow angle, the initial axial and tangential velocity and the swirl number of the swirl spray are successfully determined at various operating conditions. The experimental results showed that the initial liquid film thickness, flow angle and flow divergence are remained constant when the injection pressure is increased. However, initial film conditions are severely changed when the fuel temperature is increased. The swirl number remained constant when the injection pressure is increased while it showed increased value at high fuel temperature condition.

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Effect of Non-Uniform Mixture on Cycle Fluctuation of Multi-Cylinder Spark Ignition Engine(I) (다기통 전기점화기관의 혼합기 불균일화가 사이클 변동에 미치는 영향 (I))

  • 송재학;이용길;박경석;양옥룡
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.16 no.9
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    • pp.1736-1743
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    • 1992
  • The combustion in the cylinder of spark ignition engine is completed after the delayed time that the liquid film fuel is vapourized as flowing into the combustion chamber. It is necessary to enhance the homogeneity of mixture and the combustion phenomenon in order to improve the heat efficiency and the emission characteristics of spark ignition engine. The main purpose of this paper is to manufacture a combustion analyzing system and examine closely the influence of non-uniformity due to the liquid film fuel flowing in the intake manifold on the combustion characteristics by using a 4 stroke multi- cylinder spark ignition engine. Moreover, with each cylinder, the interpretation of combustion characteristics by indicator diagram and the concentration of exhaust gas were investigated.

Perfluorinated Sulfonic Acid Ionomer-PTFE Pore-filling Membranes for Polymer Electrolyte Membrane Fuel Cells (고분자전해질연료전지용 과불소계 술폰화 이오노머-PTFE 강화막)

  • Kang, Seong Eun;Lee, Chang Hyun
    • Membrane Journal
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    • v.25 no.2
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    • pp.171-179
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    • 2015
  • Perfluorinated sulfonic acid ionomers (PFSAs) have been widely as solid electrolyte materials for polymer electrolyte membrane fuel cells, since they exhibit excellent chemical durability under their harsh application conditions as well as good proton conductivity. Even PFSA materials, however, suffer from physical failures associated with repeated membrane swelling and deswelling, resulting in fairly reduced electrochemical lifetime. In this study, pore-filling membranes are prepared by impregnating a Nafion ionomer into the pore of a porous PTFE support film and their fundamental characteristics are evaluated. The developed pore-filling membranes exhibit extremely high proton conductivity of about $0.5S\;cm^{-1}@90^{\circ}C$ in liquid water.