• Title, Summary, Keyword: Porous Media

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

  • Jeong, Seung-Woo,
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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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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COMPUTATIONAL ANALYSIS ON DRYING OF POROUS MEDIA (다공성 매질의 건조 해석)

  • Lee, Ju-Seok;Lee, Chang-Hwan;Bae, Young-Min;Moon, Young-J.
    • 한국전산유체공학회:학술대회논문집
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    • pp.145-150
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    • 2009
  • In this study, characteristics of microwave and convective drying are studied by using a multiphase porous media model. Temperature and moisture profiles for hot-air convective heating and microwave heating of 1-D porous media with varying time and space are numerically investigated. This result shows the microwave drying method is more effective than the convective drying method. Comparing to convective drying, microwave drying can increase temperature and evaporation rate significantly since microwave generates internal heat and increases internal pressure, which results in moisture movement toward the surface on which moisture is vaporized.

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Meshfree consolidation analysis of saturated porous media with stabilized conforming nodal integration formulation

  • Wang, Dongdong;Xie, Pinkang;Lu, Hongsheng
    • Interaction and multiscale mechanics
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    • v.6 no.2
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    • pp.107-125
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    • 2013
  • A strain smoothing meshfree formulation with stabilized conforming nodal integration is presented for modeling the consolidation process in saturated porous media. In the present method, nodal strain smoothing is consistently introduced into the meshfree approximation of strain and pore pressure gradient variables associated with the saturated porous media. Meanwhile, in order to achieve a consistent numerical implementation, a smoothing approximation of the meshfree shape function within a nodal representative domain is also proposed in the stiffness construction. The resulting discrete system of equations is all expressed in smoothed nodal measures that are very efficient for numerical evaluation. Subsequently the space-time fully discrete equations are further established by the generalized trapezoidal rule for time integration. The effectiveness of the proposed meshfree consolidation analysis method is systematically illustrated by several benchmark problems.

Experimental Study on the Partial Oxidation Reforming of CH4/O2 Mixture in Two-Section Porous Media (CH4/O2 혼합기의 2단 다공체 내 부분산화 개질에 관한 실험적 연구)

  • Guahk, Young Tae;Lee, Dae Keun;Ko, Chang-Bog
    • 한국연소학회:학술대회논문집
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    • pp.249-251
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    • 2014
  • Synthesis gas such as hydrogen and carbon monoxide was produced from $CH_4//oxygen$ mixture using two-section porous media combustor. Heat recirculation through the inner foam structure could extend the flow velocity of stable region over the laminar burning velocity. $H_2/CO$ ratio and module M from concentration of flue gas measured by Gas Chromatography was similar to those calculated by equilibrium. But it was made sure that the heat loss effect becomes more influential than heat recirculation effect as the mixture gets richer. To generate synthesis gas appropriate for methanol production, insulated pressurized porous media combustor will be designed and built in the future.

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Cryogenic flow behavior in porous media with experimental approach

  • Choi, Sung-Woong;Kwon, Jae-Sung;Kim, Bum-Soo;Yang, Jeong-Hyeon
    • Journal of Advanced Marine Engineering and Technology
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    • pp.818-822
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    • 2018
  • When applied to transportation, cryogenic technology uses the efficiency of volume reduction due to gas liquefaction. Much research is underway with the technology expanding to applications for defense and medicine. To use cryogenic technology, an understanding of the entire system, including that of the behavior of cryogenic fluids and the related heat transfer, is essential. In this study, experiments were conducted to investigate the behavior of a cryogenic fluid in a porous medium, which is widely used in cryogenic systems. Results showed that the pressure distribution in the porous medium was nonlinear with a positive curvature. By introducing a mass sink term in the mass conservation equation, this pressure distribution could be explained. In contrast, the pressure distribution in porous media under saturated flow conditions is constant.

Porous Media Modelling and Verification of Thermal Analysis for Inlet and Outlet Ducts of Spent Fuel Storage Cask (사용후핵연료 저장용기 유로입출구의 다공성매질 모델링 및 열해석 검증평가)

  • Lee, Ju-Chan;Bang, Kyung-Sik;Choi, Woo-Seok;Seo, Ki-Seog;Ko, Sungho
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.16 no.2
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    • pp.223-232
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    • 2018
  • Bird screen meshes are installed at the air inlet and outlet ducts of spent fuel storage casks to inhibit the intrusion of debris from the external environment. The presence of these screens introduces an additional resistance to air flow through the ducts. In this study, a porous media model was developed to simplify the bird screen meshes. CFD analyses were used to derive and verify the flow resistance factors for the porous media model. Thermal analyses were carried out for concrete storage cask using the porous media model. Thermal tests were performed for concrete casks with bird screen meshes. The measured temperatures were compared with the analysis results for the porous model. The analysis results agreed well with the test results. The analysis temperatures were slightly higher than the test temperatures. Therefore, the reliability and conservatism of the analysis results for the porous model have been verified.

Basic Study on Flame-Stabilization Characteristics in a Multi-Channel Combustor via a Model of a Porous-Media Combustor (다공성 연소기 모델로서의 다중 채널 연소기 내부 화염의 안정화 특성 기초 연구)

  • Park, Seung-Il;Lee, Min-Jung;Kim, Nam-Il
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.35 no.8
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    • pp.815-823
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    • 2011
  • Combustion phenomena in porous media combustors are widely used in industrial fields for the combustion of lowgrade fuels and the regeneration of combustion heat. However, studies of combustion phenomena in porous media have been limited, because these phenomena are difficult to observe, and the configurations of porous media are complex. We propose a simple model combustor: a multi-channel combustor that consists of many layers of combustion channels made of quartz plates. We conducted an experimental observation of the flames in the multi-channel combustor and obtained experimental results for the flame stabilization limits. Flames formulated in the multi-channel combustor showed variation in the spatial distribution depending on the heat transfer between neighboring channels. A simple analytical model was developed and the variation in the flammability limits of the multi-channel combustor was discussed. This study will enhance our understanding of flame behavior in a porous-media combustor.

An experimental study on positioning conformance control of starch gelant in the heterogeneous porous media by using CT technology

  • Zhang, Lei;Xu, Hongming;Pu, Chunsheng;Yuan, Guangyu;Leng, Guangyao;Zhang, Chunlei
    • Journal of Industrial and Engineering Chemistry
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    • v.54
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    • pp.107-116
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    • 2017
  • In order to increase the economic efficiency of conformance control in the time of low oil price, a gelant should be injected into the specified location (positioning conformance control) to improve the swept volume in the maximum extent in the heterogeneous oil reservoir. For this purpose, an in-situ cross-linking polymer gelant (it is consisting of modified starch, acrylamide, N, N'- methylene diacrylamide, and potassium persulfate) is taken as the object of study by CT scan. Based on the dynamic and visible images of fluids distribution in the porous media, the gelant can be used to achieve the positioning conformance control because it can almost maintain a whole slug during transportation in porous media. According to the relationship of transportation distance and injection volume of the gelant in porous media, the gelant can be displaced to the specified location in porous media. In addition, the characteristics of water flooding of heterogeneous porous media before and after positioning conformance control are studied by CT scan, which can investigate the function of positioning conformance control and the extent of improving the swept volume in the heterogeneous reservoirs. The experimental results in this paper can provide theoretical guidance for the practical application of positioning conformance control in the heterogeneous oil reservoirs.

Advanced Wastewater Treatment Using Anoxic-Aerobic Reactor Filled with Porous Media (다공성 미디어를 충진한 혐기-호기 반응조를 이용한 하수고도처리에 관한 연구)

  • Kim, Dong-Ha
    • Journal of Korean Society of Water and Wastewater
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    • v.21 no.1
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    • pp.83-89
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    • 2007
  • A biological anoxic-aerobic reactor filled with porous media was operated in lab scale for the advanced wastewater treatment. The experiments were conducted for 6 months with three HRTs (4, 6, 8hr) and temperature of $23{\sim}25^{\circ}C$. Some other experimental conditions were as follows; nitrification reactor (MLSS 4,500mg/L, DO 3.3mg/L, $23{\sim}28^{\circ}C$), denitrification reactor(MLSS 8,000mg/L, ORP -100mV, Temp.$19{\sim}23^{\circ}C$). Average removal efficiencies of SS, $BOD_5$, $COD_{Cr}$, T-N, and T-P were 97.8%, 95.5%, 94.5%, 80.2%, and 60.6%, respectively. The reactor filled with porosity media showed stable removal capacity for organics and nutrients. Fast and complete nitrification and denitrification were accomplished. Maintaining high MLSS with porous media in the nitrification and denitrification reactor appears to enhance the nitrogen removal process. For the higher T-P removal, some coagulant addition process will be needed.

The Mixed Finite Element Analysis for Nearly Incompressible and Impermeable Porous Media Using Parallel Algorithm (병렬알고리즘 이용한 비압축, 비투과성 포화 다공질매체의 혼합유한요소해석)

  • Tak, Moon-Ho;Kang, Yoon-Sik;Park, Tae-Hyo
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.23 no.4
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    • pp.361-368
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    • 2010
  • In this paper, the parallel algorithm using MPI(Message-Passing Interface) library is introduced in order to improve numerical efficiency for the staggered method for nearly incompressible and impermeable porous media which was introduced by Park and Tak(2010). The porous media theory and the staggered method are also briefly introduced in this paper. Moreover, we account for MPI library for blocking, non-blocking, and collective communication, and propose combined the staggered method with the blocking and nonblocking MPI library. And then, we present how to allocate CPUs on the staggered method and the MPI library, which is related with the numerical efficiency in order to solve unknown variables on nearly incompressible and impermeable porous media. Finally, the results comparing serial solution with parallel solution are verified by 2 dimensional saturated porous model according to the number of FEM meshes.