• 제목/요약/키워드: Fuel Flow

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Analysis of Channel Flow Low During Fuelling Operation of Selected Fuel Channels at Wolsong NPP

  • I. Namgung;Lee, S.K.
    • Nuclear Engineering and Technology
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    • 제34권5호
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    • pp.502-516
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    • 2002
  • Wolsong NPP are CANDU6 type reactors and there are 4 CANDU6 type reactors in commercial operation. CANDU type reactors require on-power refuelling by two remote controlled F/Ms (Fuelling Machines). Most of channels, fuel bundles are float by channel coolant flow and move toward downstream, however in about 30% of channels the coolant flow are not sufficient enough to carry fuel bundles to downstream. For those channels a special device, FARE (Flow Assist Ram Extension) device, is used to create additional force to push fuel bundles. It has been showing that during fuelling operation of some channels the channel coolant flow rate is reduced below specified limit (80% of normal), and consequently trip alarm signal turns on. This phenomenon occurs on selected channels that are instrumented for the channel flow and required to use the FARE device for refuelling. Hence it is believed that the FARE device causes the problem. It is also suspected that other channels that do not use the FARE device for refuelling might also go into channel flow low state. The analysis revealed that the channel How low occurs as the FARE device is introduced into the core and disappears as the FARE device is removed from the core. This paper presented the FARE device behavior, detailed fuelling operation sequence with the FARE device and effect on channel flow low phenomena. The FARE device components design changes are also suggested, such as increasing the number or now holes in the tube and flow slots in the ring orifice.

왕복유동을 이용한 확산증대 효과에 대한 연구 (Enhanced diffusion by using pulsating flow)

  • 황용신;이대영;김서영;최훈;차석원
    • 한국신재생에너지학회:학술대회논문집
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    • 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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    • pp.538-541
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    • 2008
  • This study considers the feasibility of the concentration control of the feul and air by oscillating flow in the channel of Fuel Cells. Fuel Cell Stack performance is largely influenced by the fuel and air concentration. If the fuel and air concentration is lower than stoichiometry 1.25 of the fuel and 2.5 of the air, its performance deteriorates seriously because of the fuel and air starvation. In this respect the optimization of the fuel and air concentration is crucially important to maximize fuel cell stack performance. In this work, the effects of oscillating actuation are studied to control the concentration. Two important nondimensional parameters are introduced, each of which represents either the oscillating frequency or the oscillating amplitude. It is shown how these factors affect the stack performance and the efficiency of the fuel cell stack stack.

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연료극 왕복유동이 직접 메탄올 연료전지에 미치는 영향에 대한 해석적 연구 (Analytical Study on the Oscillating Flow Effect in a Anode Channel of Direct Methanol Fuel Cells)

  • 황용신;이대영;김서영;최훈;차석원
    • 한국신재생에너지학회:학술대회논문집
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    • 한국신재생에너지학회 2007년도 추계학술대회 논문집
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    • pp.27-30
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    • 2007
  • This study considers the feasibility of the concentration control of the methanol solution by oscillating flow in the anode channel of passive type Direct Methanol Fuel Cells(DMFC). DMFC stack performance is largely influenced by the fuel concentration. If the fuel concentration is either lower than 0.5M or more than 2M, its performance deteriorates seriously because of the fuel starvation or the fuel crossover. In this respect the optimization of the fuel concentration is crucially important to maximize the DMFC stack performance. In this work, the effects of oscillating actuation in the fuel supply are studied to control the fuel concentration. Two important nondimensional parameters are introduced, each of which represents either the oscillating frequency or the oscillating amplitude. It is shown how these factors affect the stack performance and the efficiency of the DMFC stack.

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최신 전투기 사례를 통한 T-50 FFP 시스템 최적 설계 연구 (A Study on Optimal design of T-50 Aircraft FFP system through a case of F-16 Aircraft)

  • 남용석;김태환;정년수
    • 항공우주시스템공학회지
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    • 제4권1호
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    • pp.10-14
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    • 2010
  • The Fuel system of T-50 Advanced Trainer is equipped with two boost pump and fuel flow proportioner for feeding fuel to turbo jet engine. when an unexpected failure occurs, they can feed the fuel to turbo jet engine which fuel quantity required. fuel quantity control method is applied for minimizing the center of gravity change. and fuel quantity control method is controlled by FQMS(Fuel Quantity Measuring System) and FFP(Fuel Flow Proportioner). This paper presents life cycle extension plans of FFP hydraulic motor by design improvements of connecting and arrangement of pipe comparing with KF-16.

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압력변동이 연료 분사구에서의 당량비 변동에 미치는 영향에 관한 수치 해석 (Numerical Simulation of the Effect of Pressure Fluctuation on the Modulation of Equivalence Ratio at the Fuel Injection Hole)

  • 김현준;홍정구;신현동
    • 대한기계학회논문집B
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    • 제31권3호
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    • pp.292-299
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    • 2007
  • In gas turbine technology, the flame stability is inherently greater in conventional diffusion type combustion over a wider range fuel to oxidizer ratio. However, premixed type combustion which has narrow flame stability region, is widely used due to environmental reason. It has been observed in experiments that combustion instability of low frequency (${\sim}10Hz$) results from the modulation of equivalence ratio at fuel injection hole when a pressure fluctuation propagates upwards along the channel of the burner under an unchoked fuel flow condition. In this study, a commercial program was used to determine how the fuel flow rate changed with respect to the pressure, velocity of the fuel flow and the mass fraction in a choked and an unchoked condition. The calculation focuses on the upstream of the dump plane to know how the forced pressure with the fuel injection conditions affects the modulation of the equivalence ratio. Therefore, it is found that pressure fluctuation leads to oscillation of mass flow rate and then results in equivalence ratio modulation under the unchoked fuel flow condition.

플러딩 조건 하에서의 고분자전해질형 연료전지 GDL 표면과 공기극 유로 채널에서의 물방울 유동 특성 고찰 (Investigation of Water Droplet Behaviour on GDL Surface and in the Air Flow Channel of a PEM Fuel Cell under Flooding Conditions)

  • 김한상;민경덕
    • 한국수소및신에너지학회논문집
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    • 제23권5호
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    • pp.476-483
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    • 2012
  • Proper water management is crucial for the efficient operation of polymer electrolyte membrane (PEM) fuel cell. Especially, for automotive applications, A novel water management that can avoid both membrane dry-out and flooding is a very important task to achieve good performance and efficiency of PEM fuel cells. The aim of this study is to investigate the liquid water behavior on the gas diffusion layer (GDL) surface and in the cathode flow channel of a PEM unit fuel cell under flooding conditions. For this purpose, a transparent unit fuel cell is devised and fabricated by modifying the conventional PEM fuel cell design. The results of water droplet behavior under flooding conditions are mainly presented. The water distributions in the cathode flow channels with cell operating voltage are also compared and analyzed. Through this work, it is expected that the data obtained from this fundamental study can be effectively used to establish the basic water management strategy in terms of water removal from the flow channels in a PEM fuel cell stack.

모델연소기 선회유동장에서의 속도 및 분무특성 (Velocity and Spray Characteristics under Swirl Flows in a Model Combustor)

  • 배충식;이동훈
    • 한국분무공학회지
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    • 제3권2호
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    • pp.42-50
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    • 1998
  • The effect of swirl flows un the fuel spray characteristics were investigated for various swillers in a model combustor. The interaction between the flow field and fuel spray in the main combustion tone made by frontal devices including fuel injection nozzles and swirlers. which were characterized by flow velocities, fuel droplet sizes and their distributions which were measured by APV(Adaptive Phase/Doppler Velocimetry) under atmospheric condition at 320cc/min kerosine fuel flow and 0.04kg/sec air supply. A dual swirler with circumferential two-stage swirl vanes of $40^{\circ}\;and\;45^{\circ}$ vanes in different directions and two single-stage swillers of $40^{\circ}$ vanes with 12 and 16 vanes were tested. It was found that the dual swirler has the largest recirculating zone with highest reverse flow velocity. The strongest swirl flow was found at the boundary of recirculation zone. Small fuel droplets were observed in the main axial stream and inside the recirculation zone when swirling flow field were generated by the frontal devices. These findings could give the tips on the optimal design of frontal devices to realize low emissions in gas turbine combustion.

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PERFORMANCE CHARACTERISTICS OF A PROTON EXCHANGE MEMBRANE FUEL CELL(PEMFC) WITH AN INTERDIGITATED FLOW CHANNEL

  • Lee, P.H.;Cho, S.A.;Han, S.S.;Hwang, S.S.
    • International Journal of Automotive Technology
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    • 제8권6호
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    • pp.761-769
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    • 2007
  • The configuration of the flow channel on a bipolar plate of a proton exchange membrane fuel cell(PEMFC) for efficient reactant supply has great influence on the performance of the fuel cell. Recent demand for higher energy density fuel cells requires an increase in current density at mid voltage range and a decrease in concentration overvoltage at high current density. Therefore, an interdigitated flow channel where mass transfer rate by convection through a gas diffusion layer is greater than the mass transfer by a diffusion mechanism through a gas diffusion layer was recently proposed. This study attempts to analyze the i-V performance, mass transfer and pressure drop in interdigitated flow channels by developing a fully three dimensional simulation model for PEMFC that can deal with anode and cathode flow together. The results indicate that the trade off between performance and pressure loss should be considered for efficient design of flow channels. Although the performance of the fuel cell with interdigitated flow is better than that with conventional flow channels due to a strong mass transfer rate by convection across a gas diffusion layer, there is also an increase in friction due to the strong convection through the porous diffusion layer accompanied by a larger pressure drop along the flow channel. It was evident that the proper selection of the ratio of channel and rib width under counter flow conditions in the fuel cell with interdigitated flow are necessary to optimize the interdigitated flow field design.

Fretting Wear of Fuel Rods due to Flow-Induced Vibration

  • Kim, Yong-Hwan;Jeon, Sang-Youn;Kim, Jae-Won
    • 한국원자력학회:학술대회논문집
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    • 한국원자력학회 1996년도 춘계학술발표회논문집(3)
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    • pp.21-26
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    • 1996
  • Recently several PWR Nuclear Plant experienced fuel rod fretting wear failures due to Flow Induced Vibration. When such multi-span supported fuel assembly has vibration excitation, it is important to know how fretting wears are progress and when the fuel rods are start to failure. In this study, we estimate the amount of wear depth using Archard theory when the fuel rod starts to relative motion against spacer grid dimples.

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직접분사식 가솔린 엔진에서 분사시기와 흡입유동이 실린더 내 연료의 거동에 미치는 영향 (Effects of Injection Timing and Intake Flow on In-Cylinder Fuel Behavior in a GDI Engine)

  • 이정훈;강정중;김덕줄
    • 한국자동차공학회논문집
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    • 제11권6호
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    • pp.7-13
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    • 2003
  • The purpose of this study is to investigate the effect of the in-cylinder flows and different injection timings on fuel behavior in the cylinder of a GDI engine. Three different flows types induced by using masked port, unmasked port, and port deactivation were tumble, swirl&tumble, and high swirl respectively. LIEF technique was applied to investigate the mixture formation and fuel distribution at ignition time in the transparent engine with optical access through the piston top and upper part of cylinder liner. Injection timings of 180,90, and 60 degrees before TDC were examined. It was found that tumble flow was more effective on the homogeneous mixture formation than other flow and swirl flow transported more fuel vapor to the exhaust side at early injection mode, and swirl and swirl & tumble flow made fuel vapor concentrate around the cylinder center at late injection mode.