• Title, Summary, Keyword: Porous Media

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A Detailed Examination of Various Porous Media Flow Models for Collection Efficiency and Pressure Drop of Diesel Particulate Filter (DPF의 PM 포집효율 예측을 위한 다양한 다공성 매질 유동장 모델 해석)

  • Jung, Seung-Chai;Yoon, Woong-Sup
    • Transactions of the Korean Society of Automotive Engineers
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    • v.15 no.1
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    • pp.78-88
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    • 2007
  • In the present study a detailed examination of various porous media models for predicting filtration efficiency and pressure drop of diesel particulate filter (DPF), such as sphere-in-cell and constricted tube models, are attempted. In order for demonstrating their validities of correct estimation on permeability, geometry of property configurations common in commercial cordierite DPFs are correlated to the porous media flow models, and validations of predicted filtration efficiencies due to the use of different unit collectors are made with experiments. The result shows that the porosity, pore size and permeability of cordierite DPF can be successfully correlated by Kuwabara flow field with correction factor of 0.6. The unit collector efficiency predicted by sphere-in-cell model agrees very well with measurements in accumulation mode, whereas that by constricted tube model with significant prediction error.

A Study on the Quality Improvement of Secondary Treatment Effluent Utilize the Natural Purification Method (자연정화공법을 이용한 2차 하수처리수의 수질 개선에 관한 연구)

  • Ahn, Tae Woong;Choi, I Song;Oh, Jong Min
    • Journal of Environmental Impact Assessment
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    • v.18 no.2
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    • pp.79-87
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    • 2009
  • This study was performed for the application of porous concrete blocks and aquatic plants for the water purification in small urban stream. This study investigated the ability of water purification according to various environments, algae and aquatic plants. When the porous concrete was used as contact media, the average removal efficiencies of SS, BOD and COD were 85~95%, 50~60% and 65~75%, respectively. Also, when the porous concrete and aquatic plants was used the average removal efficiency of SS, BOD and COD were 90~95%, 60~70% and 70~80%, respectively. As the results, average removal efficiency of total nitrogen, at the condition of the porous concrete and aquatic plants, was about 40-50%, then, that of total phosphorus was about 60-70%.

Electrochemical Ionic Mass Transfer Correlation in Fluid-Saturated Porous Layer

  • Cho, Eun Su
    • Korean Chemical Engineering Research
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    • v.53 no.6
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    • pp.814-817
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    • 2015
  • A new ionic mass transfer correlation is derived for the fluid-saturated, horizontal porous layer. Darcy-Forchheimer model is used to explain characteristics of fluid motion. Based on the microscales of turbulence a backbone mass transfer relation is derived as a function of the Darcy-Rayleigh number, $Ra_D$ and the porous medium Schmidt number, $Sc_p$. For the Darcy's limit of $Sc_p{\gg}Ra_D$, the Sherwood number, Sh is a function of $Ra_D$ only. However, for the region of high $Ra_D$, Sh can be related with $Ra_DSc_p$. Based on the present backbone equation and the electrochemical mass transfer experiments which are electro plating or electroless plating, the new ionic mass transfer correlation is suggested in the porous media.

Experimental Study and Setup of Its Apparatus for the Formation of Hydrate in Porous Media (다공질암에서의 하이드레이트 유동실험을 위한 실험장치 제작 및 형성 실험 연구)

  • Lee Hoseob;Kang Hyun;Sung Wonmo
    • Journal of the Korean Institute of Gas
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    • v.6 no.4
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    • pp.8-16
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    • 2002
  • Since hydrate has been discovered on the earth, many numbers of experimental studies have been conducted for characterizing the fundamental properties of hydrates, such as equilibrium conditions, thermodynamic properties, structures, kinetics, etc. It is considered naturally occurred hydrates in porous rocks have a great potential as a future of unconventional energy resources, and the investigations of formation and dissociation of hydrates in porous media are required. In this study, an experimental apparatus was designed to perform experiments of hydrates in porous core. With the apparatus developed, firstly, isochoric experiments were conducted to find hydrate equilibrium conditions in porous media, and the results were compared with reference data to verify experimental apparatus and methods in this study. Secondly, experiment of formation was examined by observing the behaviors of pressure and electrical resistance and the effects of initial water saturation on formation were analysed.

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Nonlinear Contact Analysis of the Air Plate in a Fuel Cell (연료전지 공기판의 비선형 접촉 해석)

  • Park, Jung-Sun;Yang, Ji-Hae;Im, Jong-Bin
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.32 no.3
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    • pp.22-29
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    • 2004
  • Deformation of the porous media has influence on performance of a proton exchange membrane fuel cell (PEMFC). The stress distributions and deformation of the porous media are major factors for safe and efficient operation in the PEMFC. In this paper, nonlinear contact analysis of air plate and porous media is performed under a working condition to predict the performance characteristics of the air plates. Two kinds of models are suggested for this study. The first porous media model has nonlinear material properties. The second model has nonlinear material properties with contact condition between porous media and air plate. The numerical analysis results of the two models are somewhat different. It is shown that the nonlinear contact analysis is required for the design study of the PEMFC.

A study on measurement of physical parameters using electromagnetic wave of the compacted saturated soil (고주파수 전자기파를 이용한 압밀 포화토 물성치 측정을 위한 연구)

  • Kim, Man-Il;Kim, Hyoung-Soo;Suk, Hee-Jun
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.354-361
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    • 2005
  • Physical parameters such as porosity and effective porosity are important physical parameters that determine the transfer and movement of water and solutes in porous media. Various methods of determining these parameters have been developed, with varying degrees of accuracy and applicability. Most of the existing methods produce static results. They do not produce instantaneous and real time of porosity and effective porosity in a porous media. In this study, a new permittivity method called Frequency Domain Reflectometry with Vector analyzer (FDR-V) is proposed to determine the porosity and effective porosity of some sand samples in the laboratory. The advantage of the FDR-V method is that it instantaneously determines the temporal variation of dielectric constants of porous media. Then, the porosity and the effective porosity of porous media are computed using well established empirical equations. Results obtained from the FDR-V method compared favorably with results from other permittivity methods such as gravimetric, injection and replacement tests. The ratio of effective porosity to porosity was $85{\sim}92%$, when FDR-V was used. This value compared favourably with 90%, which has been usually quoted in previous studies. Considering the convenience and its applicability, the measurement system of FDR-V permittivity holds a great potential in porous media and contaminant transport studies.

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Probabilistic Characteristics of Effective Diffusion Coefficient in the Porous Media

  • Khim, Jeehyeong
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • pp.58-62
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    • 1996
  • To check the variability of the effective diffusion coefficient in the unsaturated porous soil media. a Monte Carlo simulation was done for the equation suggested by Millington and Quirk(1961). The results shows that the probability density function of D$_{c}$/D$_{o}$ is positively skewed. It means the chance of having less effective diffusion coefficient values in the soil media than mean value is high. Also, the distribution types of D$_{c}$/D$_{o}$ are about same regardless of assumed distribution types of input parameters.ers.ers.

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Silver Coating on the Porous Pellets from Porphyry Rock and Application to an Antibacterial Media (반암(맥반석)으로 제조한 다공성 펠렛의 Ag 담지 및 항균 메디아로서의 적용)

  • Han, Yo-Sep;Kim, Hyun-Jung;Shin, Young-Seop;Park, Jai-Koo;Ko, Jae-Churl
    • Journal of the Korean Ceramic Society
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    • v.46 no.1
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    • pp.16-23
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    • 2009
  • The porous pellets were prepared from porphyry by slurry foaming method. The effect of sintering temperatures on pore structure of porous porphyry pellets with different extension ratio ($E_R$) was investigated by specific surface area, water absorption and porosity, which changed with sintering temperatures. When the sintering temperatures increased from $975^{\circ}C$ to $1075^{\circ}C$, specific surface area and water absorption of the all samples decreased. In case of the sample with an equal sintering temperature, $E_R=3.0$ pellets had little influence on pore structure compared to the $E_R=2.0$ pellets. As a results, it was shown by SEM that facilitated formation of micro pores at $E_R=2.0$ pellets shrunk increasingly after sintering process. At $E_R=3.0$ and sintering temperature at $1025^{\circ}C$, optimum conditions of the porous porphyry porous pellets was found. Also, Escherichia coli removal efficiency of the silver-containing porphoyry porous pellets was measured for the feasibility as a antibacterial media. The antibacterial activity of prepared silver-containing sample was maintained above 90% for 40 days.

Spatial moment analysis of multispecies contaminant transport in porous media

  • Natarajan, N.;Kumar, G. Suresh
    • Environmental Engineering Research
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    • v.23 no.1
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    • pp.76-83
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    • 2018
  • Spatial moment analysis has been performed on the concentration of the first species in a multispecies solute transport in porous media. Finite difference numerical technique was used in obtaining the solute concentration. A constant continuous source of contaminant was injected at the inlet of the domain. Results suggest that the decaying of solute mass increases as the magnitude of mean fluid velocity increases. The dispersion coefficient is highly time dependent under decaying of solutes with a complex behavior of mixing of solutes. The solute mobility and mixing varies non-linearly with time during its initial period, while the same ceases with higher decay rates of the first species much faster.

Finite element solutions of natural convection in porous media under the freezing process (동결과정을 포함한 다공층에서 자연대류에 대한 유한요소 해석)

  • Lee, Moon-Hee;Choi, Chong-Wook;Seo, Suk-Jin;Park, Chan-Guk
    • Proceedings of the KSME Conference
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    • pp.51-56
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    • 2000
  • The Finite Element Solutions Is reported on solid-liquid phase change in porous media with natural convection including freezing. The model is based on volume averaged transport equations, while phase change is assumed to occur over a small temperature range. The FEM (Finite Element Method) algorithm used in this study is 3-step time-splitting method which requires much less execution time and computer storage the velocity-pressure integrated method and the penalty method. And the explicit Lax-Wendroff scheme is applied to nonlinear convective term in the energy equation. For natural convection including melting and solidification the numerical results show reasonable agreement with FDM (Finite Difference Method) results.

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