• 제목, 요약, 키워드: Porous Media

검색결과 554건 처리시간 0.051초

다공성물질을 이용한 초단열 연소장치에서의 연소특성의 실험적 연구 (An Experimental Study on the Combustion Characteristics with Superadiabatic Combustor in Porous Media)

  • 채재우;;심민섭;정성찬
    • 설비공학논문집
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    • v.6 no.4
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    • pp.399-405
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    • 1994
  • Beacuse of the energy resources exhaustion, the aggravating environmental air pollution and the smoke phenomena etc., the importance of clean gas fuel compared with liquid fuel is highly considered in recent years. The combustion system which consists of porous media is actively studied as a new method for solving above problems. Therefore, excess enthalpy combustion using porous media was interested by many researchers and investigated through numerical and experimental analysis. In this study, the simplified combustor has the unique combustion characteristics of mixture gas preheated effect using radiative and convective heat energy by changing the flow passage of unburned gas with solenoid valves and has the intensive excess enthalpy phenomena As the result of according to reduce equivalence ratio, flame temperature was remarkably higher than adiabatic flame temperature. This show the ability of super-lean combustion.

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

  • 정승채;윤웅섭
    • 한국자동차공학회논문집
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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.

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.

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

  • 안태웅;최이송;오종민
    • 환경영향평가
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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%.

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

  • 이호섭;강현;성원모
    • 한국가스학회지
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    • v.6 no.4
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    • pp.8-16
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    • 2002
  • 하이드레이트의 존재가 밝혀진 이후 계속적인 실험연구를 통해 평형조건, 열역학적 특성, 구조 kinetics 등 하이드레이트의 기본적 물성에 대한 연구가 지속되어 왔다. 자연 상태에 존재하는 하이드레이트가 미래의 주요한 비재래형 에너지원으로 주목되면서 다공질 저류암 내에서의 하이드레이트 형성 및 해리 메커니즘 규명의 필요성이 요구되고 있다. 이에 본 연구에서는 다공질 암석코어를 사용하여 실험을 수행할 수 있는 실험장비를 제작하여 하이드레이트 형성실험을 수행하였다. 우선, 다공질암 공극 내에서의 하이드레이트 평형조건을 산출하고 기존의 실험결과와 비교함으로써 연구에 사용된 실험장비 및 실험방법의 타당성을 검증하였다. 또한 하이드레이트의 형성실험을 수행하여 압력 및 전기저항의 변화를 통해 다공질암 공각 내에서의 하이드레이트 형성현상을 관찰하였으며, 초기 물포화도가 하이드레이트 형성과정에 미치는 영향을 분석하였다.

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

  • 김만일;김형수;석희준
    • 한국지반공학회:학술대회논문집
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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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연료전지 공기판의 비선형 접촉 해석 (Nonlinear Contact Analysis of the Air Plate in a Fuel Cell)

  • 박정선;양지혜;임종빈
    • 한국항공우주학회지
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    • v.32 no.3
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    • pp.22-29
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    • 2004
  • 박막연의 변형은 고분자 전해질 연료전지의 성능에 상당한 영향을 미친다. 탄소공기판의 응력 분포는 고분자 전해질 연료전지의 안정성과 작동 효율의 중요변수이다. 본 논문에서는 작동 조건에서의 공기판과 박막면의 구조해석을 수행하였다. 박막면의 구조적 변형은 연료전지의 변수들의 분포에 영향을 미친다. 본 연구에서는 두 가지 모델에 대한 해석을 수행하였다. 한가지는 박막면의 물성치를 비선형으로 가정한 것이고, 나머지 한가지는 박막면의 물성치를 비선형으로 가정하고 공기판과 박막면의 접촉면에 접촉 조건을 적용한 경우이다. 이 두 가지 경우에 대해서 해석해본 결과 각각의 응력과 변형율의 분포에서 차이가 있음을 알 수 있었다. 이 결과를 통해 연료전지의 연구에서 비선형 접촉 해석이 필요함을 알 수 있다.

Probabilistic Characteristics of Effective Diffusion Coefficient in the Porous Media

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

  • 한요셉;김현중;신영섭;박재구;고재철
    • 한국세라믹학회지
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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.

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

  • 이문희;최종욱;서석진;박찬국
    • 대한기계학회:학술대회논문집
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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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