• Title/Summary/Keyword: Porous Media Mass Transfer

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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.

Heat and Mass Transfer in Highly Porous Media (고 다공성 물질에서 열 및 물질전달)

  • 이금배
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.14 no.3
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    • pp.685-693
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    • 1990
  • The heat transfer coefficients were calculated numerically to see the effects of radiation around the porous medium put on the flat plate at a distance from the leading edge of flat plate for the two-dimensional laminar flows. To verify the analytical model developed and invoke the heat/mass transfer analogy, an experiment was carried out using naphthalene sublimation technique. From the effects of the wake, Sherwood number is maximum around the region where the porous medium is attached. The theoretical results correspond well with the experimental results at small Darcy number. Permeability of ceramic blocks used for experiment was also measured and the Forchheimer equation is applicable in our measurement range.

First-Order Mass Transfer in a Vortex-Dispersion Zone of an Axisymmetric Groove: Laboratory and Numerical Experiments

  • Kim, Young-Woo;Kang, Ki-Jun
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.23 no.6
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    • pp.651-657
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    • 2010
  • Solute transport through a groove is affected by its vortices. Our laboratory and numerical experiments of dye transport through a single axisymmetric groove reveal evidence of enhanced spreading and mixing by the vortex, i.e., a new kind of dispersion called here the vortex dispersion. The uptake and release of contaminants by vortices in porous media is affected by the flow Reynolds number. The larger the flow Reynolds number, the larger is the vortex dispersion, and the larger is the mass-transfer rate between the mobile zone and the vortex. The long known dependence of the mass-transfer rate between the mobile and "immobile" zones in porous media on flow velocity can be explained by the presence of vortices in the "immobile" zone and their uptake and release of contaminants.

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

  • Park, Hyeong-Jin;Kim, Gyeong-Geun;Kim, Myeong-Hwan
    • Journal of Advanced Marine Engineering and Technology
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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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A Study on Heat and Mass Transfer in Porous Media (다공질 물질 속에서의 열 및 물질 전달에 대한 연구)

  • Chung, Mo
    • Solar Energy
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    • v.15 no.1
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    • pp.39-51
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    • 1995
  • A numerical scheme based on a coordinate transform into stream function-velocity potential is proposed to solve heat and momentum transfer in porous media with phase change. A significant simplification of both computational domain and governing equations can be achieved by the transform. The dispersion term in the flow through porous media, which is important at the phase change interface, can be successfully incorporated into the numerical scheme without introducing any further computational complications.

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Analysis of Heat and Mass Transfer in an Evaporative Cooler with Fully Wetted Channel (채널이 수막으로 완전히 덮여 있는 증발식 냉각기에서의 열 및 물질전달 해석)

  • Song, Chan-Ho;Lee, Dae-Yeong;No, Seung-Tak
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.25 no.12
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    • pp.1766-1775
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    • 2001
  • A theoretical analysis on the heat and mass transfer in an evaporative cooler is presented in this work. The evaporative cooler is modeled as a channel filled with porous media the interstitial surface of which is covered by thin water film. Assuming that the Lewis number is unity and the water vapor saturation curve is linear, exact solutions to the energy and vapor concentration equations are obtained. Based on the exact solutions, the characteristics of the heat and mass transfer in the evaporative cooler are investigated. The comparison of the cooling performance between the evaporative cooler and the usual sensible heat exchanger is also carried out. Obviously, the evaporative heat exchanger shows better cooling performance than the sensible heat exchanger. This is due to the latent heat of water vaporization, which results in apparent increases both in the interstitial heat transfer coefficient and the specific heat of the air stream in the evaporative cooler.

A Study on the Heat and Mass Transfer Characteristics of Vacuum Freeze Drying Process for Porous Media (다공성 물길의 진공동결건조과정에서 얼 및 물질전달 특성에 관한 연구)

  • c. s. song
    • Journal of Advanced Marine Engineering and Technology
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    • v.25 no.6
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    • pp.1341-1352
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    • 2001
  • Vacuum freeze drying process by which frozen water in a drying material is removed sublimation under vacuum condition, is now applied to various industrial field such as the manufacturing and packaging of pharmaceuticals in pharmaceutical industry, the drying of bio- products in bio-technology industry, the treatment of various quality food stuff in food technology, and so on. The Knowledge about the heat and mass transfer characteristics related with the vacuum freeze drying process is crucial to improve the efficiency of the process as well as the quality of dried products. In spite of increasing needs for understanding of the process, the research efforts in this fields are still insufficient. In this paper, a numerical code that can predict primary drying in a vial is developed based on the finite volume method with a moving grid system. The calculation program can handle the axis- symmetric and multi-dimensional characteristics of heat and mass transfer of the vial freeze drying process. To demonstrated the usefulness of the present analysis, a practical freeze drying of skim Milk solution in a vial is simulated and various calculation results are presented.

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

  • Chae, J.O.;Dobrego, K.V.;Sim, M.S.;Chung, S.C.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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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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Experimental study on the heat transfer characteristics of evaporative transpiration cooling (증발분출냉각의 열전달 특성에 관한 실험적 연구)

  • 이진호;남궁규완;김홍제;주성백
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.12 no.5
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    • pp.1130-1137
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    • 1988
  • Heat transfer characteristics of evaporative transpiration cooling was investigated experimentally in the range of coolant mass flux, 0.002kg/m$^{2}$.sec~0.015m$^{2}$.sec. Glass beads, sand and copper particles were used as porous media and distilled water was used as a conant. The existence of evaporation zone was confirmed on this experimental conditions and its length increases with increasing article size and with decreasing mass flux. In order to get the low surface temperature, porous materials with high thermal conductivity is preferred when the panicle sizes are same, and small particles with low porosity is effective in case of the same material. Due to the relatively small coolant mass flux, evaporative transpiration cooling system could be stable by the capillary effect.

Heat and mass transfer characteristics in steam reforming reactor (수증기 개질 반응기 내의 열 및 물질전달 특성에 관한 연구)

  • Lee, Shin-Ku;Lim, Sung-Kwang;Bae, Joong-Myeon
    • 한국신재생에너지학회:학술대회논문집
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    • 2006.11a
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    • pp.340-343
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    • 2006
  • In this paper, heat and mass transfer characteristics through experimental and numerical study are extensively investigated in steam reform ins reactor under given operating conditions. In order to get simulated data at outlet of the reformer, heterogeneous reactor model is incorporated. As the reaction also takes place in porous media, two medium approach is used to take into account thermally non-equilibrium phenomena between catalyst and bulk gas. In steam reforming reaction, heat transfer issue is so significant that geometrical configuration study is also conducted.

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