• 제목, 요약, 키워드: Porous Media

검색결과 554건 처리시간 0.048초

다공성 담체를 이용한 유동상 및 하이브리드 반응기에서의 질소제거 (Nitrogen Removal in Fluidized Bed and Hybrid Reactor using Porous Media)

  • 전병희
    • 대한환경공학회지
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    • v.27 no.5
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    • pp.542-548
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    • 2005
  • 부착 미생물을 이용한 다공성 담체 유동상 반응기는 하폐수중의 유기물 및 질소제거에 많이 적용되어져 왔다. 특히 생물막이 형성된 담체에서는 호기, 무산소 그리고 혐기영역이 공존하여 동시적 질산화/탈질 반응에 의한 질소제거에 유리한 환경이 제공된다고 알려져 있다. 이러한 반응을 활성화시키기 위해서는 담체표면과 내부에서 산소와 유기물등의 적절한 기질확산이 이루어져야 한다. 그러나 하폐수중의 유기물농도나 생물막의 마찰조건등 운전조건에 따라서는 표면에서의 종속영양균의 과잉성장에 의해 질소 제거 반응이 저해되기도 한다. 다공성 담체 유동상 반응기에 막모듈을 결합시킨 하이브리드 반응기는 단일조내에서 활성화된 동시적 질산화/탈질 반응으로 종래의 유동상 반응기에 비해 30% 이상 질소제거 효율이 증가하였다. 미소전극 연구를 통해 담체내부의 탈질율을 조사할 수 있으며 유동상 반응기에 비하여 하이브리드 반응기내 담체내부에서는 탈질반응에 대한 유기물의 확산에 대한 제한인자가 작으며 따라서 보다 높은 탈질율을 유지할 수 있음을 보였다.

구조 변형을 고려한 연료전지 공기판의 유동 해석 (Structural Deformation and Flow Analysis for Designing Air Plate of a Fuel Cell)

  • 양지혜;박정선
    • 대한기계학회논문집A
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    • v.28 no.7
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    • pp.877-884
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    • 2004
  • In this paper, structural analysis is performed to investigate the deformation of porous media in a proton exchange membrane fuel cell (PEMFC). Structural deformation of air plate of the fuel cell causes the change in configuration and cross sectional area of the channel. The distributions of mass flow rate and pressure are major factors to decide the performance of a PEMFC. These factors are affected by channel configuration of air plate. Two kinds of numerical air plate models are suggested for flow analyses. Deformed porous media and undeformed porous media are considered for the two models. The Numerical flow analysis results between deformed porous media and undeformed porous media have some discrepancy in pressure distribution. The pressure and velocity distribution under a working condition are numerically calculated to predict the performance of the air plates. Pressure and velocity distributions are compared for two models. It is shown that structural deformation makes difference in flow analysis results.

1차원 유동 네트워크 모델 및 다공성매질 모델을 이용한 판형 열교환기의 수치적 연구 (A Numerical Study on Plate-Type Heat Exchanger Using One-Dimensional Flow Network Model and Porous-Media Model)

  • 박재현;김민성;민준기;하만영
    • 설비공학논문집
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    • v.28 no.1
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    • pp.21-28
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    • 2016
  • A typical heat exchanger, found in many industrial sites, is made up of a large number of unitary cells, which causes difficulties when carrying out full-scale three-dimensional numerical simulations of the heat exchanger to analyze the aero-thermal performance. In the present study, a three-dimensional numerical study using a porous media model was carried out to evaluate the performance of the heat exchanger modelled in two different ways : full-scale and simplified. The pressure drop in the air side and gas side along with the overall heat transfer rate were calculated using a porous media model and the results were then compared to results obtained with a one-dimensional flow network model. The comparison between the results for two different geometries obtained using a porous media model and a one-dimensional flow network model shows good agreement between the simplified geometry and the one-dimensional flow network model. The full-scale geometry shows reasonable differences caused by the geometry such as sudden expansion and contraction.

정수지 내 유동 특성과 유공벽을 이용한 소독능 변화에 대한 수치 해석적 연구 (Numerical Analysis for Characteristics of Flow Fields and Disinfection Performances in the Clearwell with a Porous media Wall)

  • 이석원;리광훈;구자용
    • 상하수도학회지
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    • v.21 no.6
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    • pp.755-761
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    • 2007
  • Disinfection performance in clearwell is generally measured by CT, which is expressed by $C{\times}T$. C is represented by disinfection concentration, and T is represented by $T_{10}$ which means 90% contact time in clearwell. In order to improve Disinfection performance, augmentation of $T_{10}$ is required. Guide wall has been generally used to improve $T_{10}$ because $T_{10}$ changes according to flow field. In this study, porous media is proposed instead of guide wall, and disinfection performance between guide wall and porous media wall are compared. Flow field and $T_{10}$ in each clearwell are investigated as well. Improved Disinfection performance appear in case of porous media wall compare to guide wall, and best performance occur in porosity factor ${\beta}$ 1e+4.

원자로 모의 다공질 매체의 유효 열전달 계수 측정 (Measurement of the Effective Thermal Conductivity of Porous Media in the Mockup Apparatus of Reactor Vessel)

  • 김용균;황종선;이용범;최석기;남호윤
    • 한국전기전자재료학회:학술대회논문집
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    • pp.447-450
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    • 1997
  • Temperature distribution measurements in the mockup apparatus of reactor vessel were performed to determine the effective thermal conductivity of Al powder porous media where stainless steel tubes were installed with different geometry. The temperature distributions at four separated sections with different arrangements of porous media have different slopes according to the geometrical configuration. From the measured temperature distribution, effective thermal conductivity have been derived using the least square fitting method.

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Computational rock physics: Lattice-Boltzmann fluid flow simulation in porous media and its applications

  • Keehm, Young-Seuk;Mukerji, Tapan;Nur, Amos
    • 한국지구물리탐사학회:학술대회논문집
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    • pp.661-668
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    • 2003
  • This paper presents Lattice-Boltzmann simulation techniques for single-phase and two-phase fluid flow in porous media. Numerical experiments were performed in a digital rock sample from X-ray microtomography. Computed results showed very good agreement with laboratory measurements of permeability and relative permeability. Two applications using these simulation techniques show the potential of the Lattice-Boltzmann flow simulation to solve many difficult problems coupled with fluid flow in porous media.

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단열 및 다공질 대수층에서의 추적자 시험연구 (A Comparative Study of Tracer Tests in Fractured and Porous Media)

  • 이진용;이지훈;김용철;천전용;이민효;이강근
    • 한국지하수토양환경학회:학술대회논문집
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    • pp.132-135
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    • 2001
  • To understand and compare tracer transport in fractured and porous media. multiple tracer tests were conducted in Wonju and Uiwang sites. The target media were fractured in Wonju site and porous in Uiwang site. It was known that groundwater flow for the two hydrogeologic systems could be represented using a EPM approach. However, the tracer transport in the two aquifer systems was greatly different. In this study, we analyzed the different tracer transport behavior in the two systems, from which our understanding of the tracer dispersion was greatly enhanced. we used bromide and chloride as tracers.

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장방형내 함수 다공성 물질의 동결거동에 관한 실험적 연구 (An Experimental study on the Freezing Phenomena of Saturated Porous Media in a Rectangular Cavity)

  • 김병철;김종일;김진흥
    • 설비공학논문집
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    • v.3 no.5
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    • pp.386-394
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    • 1991
  • Freezing of saturated porous media contained in a rectangular cavity has been studied experimentally. Water and different diameter glass beads consitituted the liquid and porous media. Solidification front shape, the effects of bead diameter and initial liquid temperature was investigated. When the hot wall temperature was below $4^{\circ}C$, the freezing rate was higher at the top than at the bottom due to the density inversion, but with increasing the hot wall temperature the freezing rate at the top was effected by the liquid temperature and was lower than at the bottom. With increasing the bead diameter, the difference of freezing rate between top and bottom was increased and depends on thermal conductivity. When the liquid temperature was low in the beginning, the freezing rate was high, but with increasing the time almost the same with those of high temperature liquid.

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함수다공질층의 진공건조에 관한 실험적 연구 (Ⅰ) (An Experimental Study on Vacuum Drying of Water-Saturated Porous Media)

  • 박형진;김경근;김명환
    • 한국마린엔지니어링학회지
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    • v.20 no.5
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    • pp.68-75
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    • 1996
  • The vacuum drying characteristics of water-saturated porous media were studied experimentally. The water-saturated porous media, water-saturated sand layer, was heated by the isothermal bottom wall of the rectangular vessel. The vacuum drying rate and temperature distribution of the sand layer were measured and calculated under a variety of conditions of heated wall temperature, vacuum rate, and thickness of the test material. It was found that the drying rate due to the heat and mass teansfer is greatly influenced by the heated wall temperature, vacuum rate, and thickness of the test material.

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Suitable Use of Capillary Number for Analysis of NAPL Removal from Porous Media

  • Jeong, Seung-Woo,
    • 한국지하수토양환경학회:학술대회논문집
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    • pp.25-28
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    • 2004
  • The capillary number is used to represent the mobilization potential of organic phase trapped within porous media. The capillary number has been defined by three different forms, according to types of flow velocity and viscosity used in the definition of capillary number. This study evaluated the suitability of the capillary number definitions for representing TCE mobilization by constructing capillary number-TCE saturation relationships. The results implied that the capillary number should be correctly employed, according to interest of scale and fluid flow behavior. This study suggests that the pore-scale capillary number may be used only for investigating the organic-phase mobilization at the pore scale because it is defined by the pore-velocity and the dynamic viscosity. The Newtonian-fluid capillary number using Darcy velocity and the dynamic viscosity may be suitable to quantify flood systems representing Newtonian fluid behavior. For viscous-force modified flood systems such as surfactant-foam floods, the apparent capillary number definition employing macroscopic properties (permeability and potential gradient) may be used to appropriately represent the desaturation of organic-phases from porous media.

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