• Title/Summary/Keyword: Cathode Flow Rate

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Experiments on PEMFC performance enhancement by pulsating cathode flow

  • Han, Hun-Sik;Kim, Ki-Woong;Kim, Yun-Ho;Kim, Seo-Young
    • 한국신재생에너지학회:학술대회논문집
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    • 2008.05a
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    • pp.542-545
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    • 2008
  • Experiments have been performed to investigate effects of pulsating cathode flow on a 10-cell proton exchange membrane fuel cell (PEMFC) stack. For all the experiments, the flow rate, temperature and relative humidity of hydrogen at the anode inlet are fixed. The effects of the pulsating frequency, amplitude and flow rate at the cathode inlet on performance of 10-cell PEMFC are examined. The polarization and power curves show that the power output and limiting current is substantially increased when the pulsating component is added to cathode flow channel. The maximum power output increases by up to 38% and enhancement of the overall performance is more pronounced at lower flow rate region.

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Unsteady Internal Flow Analysis of a Cathode Air Blower Used for Fuel Cell System (연료전지용 캐소드 공기블로어의 비정상 내부유동장 연구)

  • Jang, Choon-Man;Lee, Jong-Sung
    • New & Renewable Energy
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    • v.8 no.3
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    • pp.6-13
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    • 2012
  • This paper describes unsteady internal flow characteristics of a cathode air blower, used for the 1 kW fuel cell system. The cathode air blower considered in the present study is a diaphragm type blower. To analyze the flow field inside the diaphragm cavity, compressible unsteady numerical simulation is performed. Moving mesh system is applied to the numerical analysis for describing the volume change of the diaphragm cavity in time. Throughout a numerical simulation by modeling the inlet and outlet valves in a diaphragm cavity, unsteady nature of an internal flow is successfully analyzed. Variations of mass flow rate, force and pressure on the lower moving plate of a diaphragm cavity are evaluated in time. The computed mass flow rate at the same pressure and rotating frequency of a motor has a maximum of 5 percent error with the experimental data. It is found that flow pattern at the suction process is more complex compared to that at the discharge process. Unsteady nature of internal flow in the cathode air blower is analyzed in detail.

Electricity generation from surface floating air cathode microbial fuel cell according to the wastewater flow-rate and the ratio of cathode surface area to anode surface area (표면부유 공기양극 미생물연료전지에서 유량 및 전극 면적비에 따른 전력생산 특성)

  • Yoo, Kyu-Seon;Song, Young-Chae;Woo, Jung-Hui;Chung, Jae-Woo;Lee, Chae-Young
    • Journal of Korean Society of Water and Wastewater
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    • v.25 no.4
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    • pp.591-596
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    • 2011
  • Surface floating air cathode microbial fuel cell (MFC) having horizontal flow was developed for the application of MFC technology. RVC (Reticulated vitreous carbon) coated with anyline was used as anode electrode and carbon cloth coated with Pt (5.0 g Pt/$m^2$, GDE LT250EW, E-TEK) was used as cathode electrode. As results of continuous operation with changing the flow rate from 4.3 mL/min to 9.5 mL/min, maximum power density of 4.5 W/$m^3$ was acquired at 5.4 mL/min, which was at 0.35 m/hr of flow velocity under anode electrode. When the ratio of cathode surface area to anode surface area($A_c/A_a$) was changed to 1.0, 0.5, and 0.25, the maximum power density of 2.7 W/$m^3$ was shown at the ratio of 1.0. As the ratio decreased from 1.0 to 0.25, the power density also decreased, which is caused by increasing the internal resistance resulted from reducing the surface area to contact with oxygen. Actually, internal resistances of the ratio of 1.0, 0.5, and 0.25 were 63.75${\Omega}$, 142.18${\Omega}$, and 206.12${\Omega}$, respectively.

Numerical Simulation of the Oscillating Flow Effect in the Channel of Polymer Electrolyte Membrane Fuel Cell (왕복 유동을 통한 확산증대 효과가 연료전지 성능에 미치는 영향에 대한 수치해석)

  • Kim, Jongmin;Kang, Kyung-Sik
    • Journal of the Korea Safety Management & Science
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    • v.20 no.4
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    • pp.7-13
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    • 2018
  • This study investigates the enhancement of the oxygen diffusion rate in the cathode channel of a proton exchange membrane fuel cell (PEMFC) by pure oscillating flow, which is the same as the mechanism of human breathe. Three-dimensional numerical simulation, which has the full model of the fuel cell including electrochemical reaction, ion and electronic conduction, mass transfer and thermal variation and so on, is performed to show the phenomena in the channel at the case of a steady state. This model could analysis the oscillating flow as a moving mesh calculation coupled with electrochemical reaction on the catalyst layer, however, it needs a lot of calculation time for each case. The two dimensional numerical simulation has carried on for the study of oscillating flow effect in the cathode channel of PEMFC in order to reduce the calculation time. This study shows the diffusion rate of the oxygen increased and the emission rate of the water vapor increased in the channel by oscillating flow without any forced flow.

A study of the hollow cathode discharge (HOLLOW CATHODE DISCHARGE의 방전 특성 연구)

  • Cho, S.M.;Seo, Y.W.;Kim, M.J.;Whang, K.W.
    • Proceedings of the KIEE Conference
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    • 1989.11a
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    • pp.139-141
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    • 1989
  • The characteristics of the hollow cathode discharge were investigated. Temperature distribution of the hollow cathode was investigated and I-V curves of the hollow cathode discharge were obtained. In this paper variables are chamber pressure, Ar gas flow rate injected through the cathode tube and the gap distance between cathode and anode. The inter electrode electron temperature and density were measured by Langmuir probe.

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Effect of Main Operating Conditions on Cathode Flooding Characteristics in a PEM Unit Fuel Cell (고분자전해질형 단위 연료전지의 주요 작동 조건이 공기극 플러딩 현상에 미치는 영향)

  • Min Kyoung-Doug;Kim Han-Sang
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.30 no.5 s.248
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    • pp.489-495
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    • 2006
  • Proton exchange membrane (PEM) should be sufficiently hydrated with a careful consideration of heat and water management. Water management has been a critical operation issue for better understanding the operation and optimizing the performance of a PEM fuel cell. The flooding on cathode side resulting from excess water can limit the fuel cell performance. In this study, the visual cell was designed and fabricated fur the visualization of liquid water droplet dynamics related to cathode flooding in flow channels. The experiment was carried out to observe the formation, growth and removal of water droplets using CCD imaging system. Effects of operating conditions such as cell temperature, air flow rate and air relative humidity on cathode flooding characteristics were mainly investigated. Based on this study, we can get the basic insight into flooding phenomena and its two-phase flow nature. It is expected that data obtained can be effectively used fur the setup and validation of two-phase PEM fuel cell models considering cathode flooding.

Hydrogen Reduction Behavior of NCM-based Lithium-ion Battery Cathode Materials (NCM계 리튬이온 배터리 양극재의 수소환원 거동)

  • So-Yeong Lee;So-Yeon Lee;Dae-Hyeon Lee;Ho-Sang Sohn
    • Journal of Powder Materials
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    • v.31 no.2
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    • pp.163-168
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    • 2024
  • As the demand for lithium-ion batteries for electric vehicles is increasing, it is important to recover valuable metals from waste lithium-ion batteries. In this study, the effects of gas flow rate and hydrogen partial pressure on hydrogen reduction of NCM-based lithium-ion battery cathode materials were investigated. As the gas flow rate and hydrogen partial pressure increased, the weight loss rate increased significantly from the beginning of the reaction due to the reduction of NiO and CoO by hydrogen. At 700 ℃ and hydrogen partial pressure above 0.5 atm, Ni and Li2O were produced by hydrogen reduction. From the reduction product and Li recovery rate, the hydrogen reduction of NCM-based cathode materials was significantly affected by hydrogen partial pressure. The Li compounds recovered from the solution after water leaching of the reduction products were LiOH, LiOH·H2O, and Li2CO3, with about 0.02 wt% Al as an impurity.

Fundamental Studies of the Electrical Characteristics of the Glow Discharge for the Development of HPLC Detector (글로우방전을 이용한 액체크로마토그라피 검출기 개발을 위한 기초특성연구)

  • 이현주;김효진
    • YAKHAK HOEJI
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    • v.39 no.4
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    • pp.427-432
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    • 1995
  • The plasma oscillation has been observed in an argon pressure between a tungsten anode and cathode consisting of an aqueous conducting solution. The effects of experimental parameters on the electrical characteristics of the glow discharge have been studied. The experimental parameters include the anode-cathode distance, pressure, methanol flow rate, and cathode materials. The glow discharge with liquid cathode and solid anode showed the potential sensitive detector for HPLC

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Performance Enhancement and Recovery Method of Open Cathode PEMFC (오픈 캐소드형 고분자전해질 연료전지의 성능향상과 회복기법)

  • Lee, Kitaek;Kim, Junbom
    • Applied Chemistry for Engineering
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    • v.28 no.1
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    • pp.118-124
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    • 2017
  • An air cooling, open cathode type polymer electrolyte membrane fuel cell (PEMFC) has the advantages of system simplification and cost effectiveness. Open cathode PEMFC could suffer from reduced performance due to the membrane dehydration in low humidity of air. Effects of the cathode air flow rate, anode purge interval and long term storage on PEMFC performance were investigated in this work. Fan voltage is an important factor on air cooling PEMFC performance because the cathode air flow rate and stack temperature were controlled by fan voltage. The dead ended anode (DEA) method was applied to increase hydrogen usage. Periodical purge was used to discharge accumulated water and gas. The influence of long term non-operating condition on PEMFC performance degradation due to the membrane dehydration was also studied and the quick recovery method was developed.

Performance Enhancement of a PEMFC by Modification of Air Inlet Flow Header Configuration (공기측 입구헤더의 형상 개선을 통한 고분자 전해질 연료전지의 성능 향상)

  • Kim, Won-Nyun;Kim, Yun-Ho;Kim, Seo-Young
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.19 no.4
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    • pp.339-345
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    • 2007
  • In the present study, a 10-cell PEMFC stack with straight type cathode flow channels is employed to investigate the effect of inlet air flow header configuration on the overall fuel cell performance. Four different types of inlet flow headers are considered and the flow patterns according to the air inlet flow header configuration are numerically obtained. The computed result for a modified header predicts about 8.5% improvement in the air flow distribution at 10-cell cathode channel inlets. Experiments are also carried out to confirm the numerical findings by measuring actual air flow distributions and the polarization curves of the PEMFC stack.