• Title/Summary/Keyword: Gas porosity

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Porosity Estimation Using the Characteristics of Porous Zeolite (다공성 제올라이트의 특성을 이용한 기공율 추정 연구)

  • Hyeji Kim;Yeon-Sook Lee;Jin Sun Cha
    • Clean Technology
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    • v.29 no.4
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    • pp.249-254
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    • 2023
  • In this study, porosity estimation was conducted by the physical properties of zeolite. Because of the difficulty of directly measuring the porosity of particulate matter, the porosity was calculated by applying the measured physical properties of zeolite to the calculation formula presented in various literature. For this purpose, the average particle size, particle size distribution, specific surface area, and pore characteristics of three types of zeolite - zeolite beta, zeolite Y, and ZSM-5 - were measured. In addition, the true density using gas and liquid phases, and two types apparent density (tap and untapped density) were measured. We calculated the porosity using these results, compare and analyzed the results, and evaluated main factors that determine the porosity.

The Characteristics Evaluation of the Gas Diffusion Layer for a PEM Fuel Cell by Computational Fluid Dynamics (CFD 해석을 이용한 PEMFC 용 기체확산층의 특성평가)

  • Kim B.H.;Choi J.P.;Jeon B.H.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.207-210
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    • 2005
  • In this paper, a two-dimensional cross-channel model was applied to investigate influence of the gas diffusion layer(GDL) property and flow field geometry in the anode side for proton exchange membrane fuel cell(PEMFC). The GDL is made of a porous material such as carbon cloth, carbon paper, or metal wire mesh. To the simplicity, the GDL is represented as a block of material containing numerous pathways through which gaseous reactants and liquid water can pass. The purpose of present work was to study the effect of the GDL thickness and the porosity, and flow field geometry by computational fluid dynamics(CFD)

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Formation of Microporosities in Sputter-Deposited AgInSbTe Thin Films and Their Behavior (스퍼터 증착시킨 AgInSbTe 박막에서 미세기공의 형성과 그 거동)

  • Kim, Myong-R.;Seo, H.;Park, J. W.;Choi, W. S.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1996.05a
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    • pp.84-89
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    • 1996
  • The nucleation and growth of microporosities was observed during the course of annealing treatment of sputter-deposited AgInSbTe thin films. There was a close correlation between the density of microporosity and the sputtering gas pressure in annealed thin films. The void density for a given composition decreased with sputtering gas pressure. It was shown from the present study that the number of porosities decreased while the average porosity size increased as the annealing temperature and holding time increased. The mechanism of porosity formation in the sputter-deposited AgInSbTe thin flus containing Ar-impurity trapped from the Ar-plasma is discussed in the present article.

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The Effect of Solvent Trap Apparatus on the Analysis of Carbonyl Compounds in Cigarette Smoke (용매 포집장치가 연기 중 Carbonyl 화합물의 분석에 미치는 영향)

  • 김효근;이존태;윤오섭;이문수
    • Journal of the Korean Society of Tobacco Science
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    • v.25 no.2
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    • pp.137-143
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    • 2003
  • Among the most popular means of mainstream smoke collection for specific analysis are solvent traps. Determination of the carbonyl compounds as their 2,4-dinitrophenylhydrazones(DNPHs) by HPLC offers increased sensitivity and reproducibility in the analysis of mainstream cigarette smoke. In this work, the mainstream smoke of a reference cigarette(lR4F) was collected in four kinds of gas washing bottles and their effects on the analysis of carbonyl compounds were investigated. The results show that the porosity of fritted glass filter in gas washing bottles exerted profound effect on the composition of the carbonyl compounds in mainstream smoke.

The Performance Analysis of Polymer Electrolyte Membrane Fuel Cells for Mobile Devices using CFD (CFD를 이용한 모바일기기용 고분자전해질 연료전지 성능해석)

  • Kim B.H.;Choi J.P.;Kang D.C.;Jeon B.H.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2006.05a
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    • pp.553-554
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    • 2006
  • This paper presents the effects of different operating parameters on the performance of a proton exchange membrane (PEM) fuel cell by a three-dimensional computational fluid dynamics (CFD) model. The effects of different operating parameters on the performance of PEM fuel cell studied using pure hydrogen on the anode side and air on the cathode side. The various parameters are temperatures, pressures, humidification of the gas steams and various combinations of these parameters. In addition, geometrical and material parameters such as the gas diffusion layer (GDL) thickness and porosity as well as the ratio between the channel width and the land area were investigated.

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Porosity Reduction in Laser Welding of Nitrided Carbon Steel (질화처리된 저탄소강 레이저 용접부의 기공 감소)

  • Ahn, Young-Nam;Kim, Cheolhee;Lee, Wonbeom;Kim, Jeonhan
    • Journal of Welding and Joining
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    • v.31 no.6
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    • pp.71-76
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    • 2013
  • Gas nitriding is a surface hardening process where nitrogen is introduced into the surface of a ferrous alloy. During fusion welding of nitrided carbon steel, the nitride inside weld metal is dissolved and generates nitrogen gas, which causes porosities - blow holes and pits. In this study, several laser welding processes such as weaving welding, two-pass welding, dual beam welding and laser-arc hybrid welding were investigated to elongate the weld pool to enhance nitrogen gas evacuation. The surface pits were successfully eliminated with elongated weld pool. However blowholes inside the weld metal were effective reduced but not fully disappeared.

Numerical Study on the Effect of Gas Diffusion Layer (GDL) Properties in Cathode on the Performance of Polymer Electrolyte Membrane Fuel Cell (PEMFC) (고분자 전해질 연료전지내의 양극 기체확산층 물성 변화가 전지성능에 미치는 영향에 관한 전산해석 연구)

  • Chun, Jeong Hwan;Jo, Dong Hyun;Lee, Ji Young;Kim, Sung Hyun
    • Korean Chemical Engineering Research
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    • v.50 no.3
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    • pp.556-561
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    • 2012
  • In this study, the effect of properties of gas diffusion layer (GDL) on the performance of polymer electrolyte membrane fuel cell (PEMFC) was investigated using the numerical simulation. The multi-phase mixture ($M^2$) model was used to calculate liquid water saturation and oxygen concentration in GDL. GDL properties, which were contact angle, porosity, gas permeability and thickness, were changed to investigate the effect of GDL properties on the performance of PEMFC. The results demonstrated that performance of PEMFC was increased with increasing contact angle and porosity of GDL, but decreased with increasing thickness of GDL. The liquid water saturation was decreased but oxygen concentration was increased at the GDL-catalyst layer interface, because the mass transfer resistance decreased as the porosity and contact angle increased. On the other hands, as the thickness of GDL increased, pathway for liquid water and oxygen gas became longer, and then mass transfer resistance increased. For this reason, performance of PEMFC decreased with increasing thickness of GDL.

Fabrication and Characteristics of Anode-Supported Tube for Solid Oxide Fuel Cell (습식법에 의한 고체산화물 연료전지용 연료극 지지체관의 제조 및 특성 연구)

  • Kim, Eung-Yong;Song, Rak-Hyeon;Im, Yeong-Eon
    • Korean Journal of Materials Research
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    • v.10 no.10
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    • pp.659-664
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    • 2000
  • To develop anode-supported tubular cell with proper porosity, we have investigated the anode substrate and t the electrolyte-coated anode tube. The anode substrate was manufactured as a function of carbon content in the range of 20 to 50 vol.%. As the carbon COntent increased, the porosity of the anode substrate increased slightly and the carbon c content with proper porosity is found to be 30 vol.%. The anode-supported tube was fabricated by extrusion process a and the electrolyte layer was coated on the anode tube by slurry coating process. The anode-supported tube was cofired successfully at $^1400{\circ}C$ in air. The porosity of the anode tube was 35%. From the gas permeation test, the anode t tube was found to be porous enough for gas supply. On the other hand, the anode-supported tube with electrolyte layer indicated a very low gas permeation rate. This means that the coated electrolyte was dense.

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Electrical Resistivity Monitoring of Gas Hydrate Formation (가스하이드레이트 형성 과정의 비저항 모니터링)

  • Lee, J.Y.;Lee, J.H.;Lee, D.S.;Lee, W.S.;Kim, S.J.;Huh, D.G.;Kim, H.T.
    • 한국신재생에너지학회:학술대회논문집
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    • 2008.10a
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    • pp.186-187
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    • 2008
  • Electrical resistivity in hydrate-bearing sediments is sensitive to porosity, gas hydrate saturation, gas content, pore fluid composition, and temperature, so electrical measurements such as well logs and electromagnetic surveys have been used to explore gas hydrate-bearing formation. The high pressure tomography cell is designed considering the effect of electrode configuration and electrical shielding on tomography measurements and the safety. The evolution of electrical conductivity during $CO_2$ hydrate formation and dissociation reflects the combined effects of concurrent changes that include ionization of dissolved $CO_2$, temperature-dependent ionic mobility, changes in the degree of saturation, ion exclusion, surface conduction, and porosity changes. Measurements during hydrate formation and dissociation require careful analysis to properly interpret signatures, in particular when out-of plane conductivity anomalies prevail.

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Porosity Reduction during Gas Tungsten Arc-Gas Metal Arc Hybrid Welding of Zinc Coated Steel Sheets (I) - Effect of Preceding Gas Tungsten Arc (GTA-GMA 하이브리드공정에 따른 자동차용 아연도금강판의 용접부 기공감소 (I) - 선행 GTA의 영향)

  • Kang, Minjung;Ahn, Young-Nam;Kim, Cheolhee
    • Journal of Welding and Joining
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    • v.34 no.4
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    • pp.40-47
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    • 2016
  • The Zn coating on automotive galvanized steel sheets can improve corrosion resistance. However, the boiling temperature of Zn is lower than the melting temperature of steel and it causes well-known spatter and porosity problem. One of most prominent solutions is a pretreatment of Zn coating by an additional welding arc prior to the main welding process. In this research, GTA and GMA are selected as heat sources for pretreatment and main welding processes, respectively. The authors suggested three possible mechanisms to reduce weld defects by the GTA pretreatment: (1) Formation of gap between the sheets; (2) Evaporation of Zn layer; (3) Oxidation of Zn layer. Among them, Zn Oxidation is the most important mechanism to reduce weld defects in the GTA-GMA hybrid process.