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Dissertations / Theses on the topic 'Transport/ mass transfer'

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Published: 14 September 2024

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1

Binder, Thomas, Christian Chmelik, Jörg Kärger, and Douglas M. Ruthven. "Mass-transfer of binary mixtures in DDR single crystals." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-182920.

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2

Weber, Sofie Aimee. "Contaminant transport and mass transfer to runoff including infiltration." Thesis, The University of Arizona, 1997. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_etd_hy0151_sip1_w.pdf&type=application/pdf.

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3

Binder, Thomas, Christian Chmelik, Jörg Kärger, and Douglas M. Ruthven. "Mass-transfer of binary mixtures in DDR single crystals." Diffusion fundamentals 20 (2013) 44, S. 1-2, 2013. https://ul.qucosa.de/id/qucosa%3A13614.

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4

Heinke, Lars, and Jörg Kärger. "Mass transfer in one-dimensional nanoporous crystals with different surface permeabilities." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-192770.

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The use of optical techniques, such as interference microscopy and IR micro-imaging, has enabled the direct observation of transient concentration profiles. In a one-dimensional crystal, surface permeabilities on opposing crystal faces are usually equal, so that mass transfer occurs symmetrically and the fluxes through both crystal faces are identical. If the surface permeabilities on opposing crystal faces are different from each other, mass transfer is not symmetrical anymore. We are going to show that the fraction of molecular uptake (or release) through a given host face is inversely proportional to the time constant of uptake/release via this crystal face. This finding permits a straightforward estimate of the influence of asymmetry on overall uptake.

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5

Inzoli, Isabella, Jean Marc Simon, and Signe Kjelstrup. "Surface resistance to heat and mass transfer in a silicalite membrane." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-193396.

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6

Remi, Julien Cousin Saint, Alexander Lauerer, Gino Baron, Christian Chmelik, Joeri Denayer, and Jörg Kärger. "The effect of crystal diversity of nanoporous materials on mass transfer studies." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-198073.

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7

Heinke, Lars. "Significance of concentration-dependent intracrystalline diffusion and surface permeation for overall mass transfer." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-194507.

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The intracrystalline concentration profiles evolving during molecular uptake and release by nanoporous materials as accessible by interference microscopy contain a lot of hidden information. For concentration-independent transport parameter, the influence of surface resistances to overall mass transfer can be calculated by correlating the actual surface concentration with the overall uptake. By using a numerical solution of Fick’s 2nd law and considering a large variety of concentration dependencies of the transport diffusivity and the surface permeability, we show that the factor by which the transport process is retarded by the surface resistance may reasonably well be estimated by the type of correlation between the actual boundary concentration and the total uptake at a given time. In this way, a novel technique of uptake analysis which may analytically be shown to hold for constant diffusivities and surface permeabilities, is shown to be quite generally applicable.

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8

Heinke, Lars, and Jörg Kärger. "Mass transfer in one-dimensional nanoporous crystals with different surface permeabilities." Diffusion fundamentals 9 (2008) 2, S. 1-6, 2008. https://ul.qucosa.de/id/qucosa%3A14139.

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The use of optical techniques, such as interference microscopy and IR micro-imaging, has enabled the direct observation of transient concentration profiles. In a one-dimensional crystal, surface permeabilities on opposing crystal faces are usually equal, so that mass transfer occurs symmetrically and the fluxes through both crystal faces are identical. If the surface permeabilities on opposing crystal faces are different from each other, mass transfer is not symmetrical anymore. We are going to show that the fraction of molecular uptake (or release) through a given host face is inversely proportional to the time constant of uptake/release via this crystal face. This finding permits a straightforward estimate of the influence of asymmetry on overall uptake.

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9

Snyder, Kevin P. "Multiphase flow and mass transport through porous media." Thesis, Virginia Tech, 1993. http://hdl.handle.net/10919/40658.

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10

Simoni, Stefano Federico. "Factors affecting bacterial transport and substrate mass transfer in model aquifers /." [S.l.] : [s.n.], 1999. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=13232.

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11

Yusuf, Mary E. "Heat transfer and mass transport studies in gas-particulate solids flows." Thesis, Glasgow Caledonian University, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.688301.

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12

Chihara, Kazuyuki, Takashi Matsumoto, and Kazunori Hijikata. "Azeotropic adsorption of organic solvent vapor mixture on high silica zeolite, mass transfer dynamics: Azeotropic adsorption of organic solvent vapor mixture on high silicazeolite, mass transfer dynamics." Diffusion fundamentals 3 (2005) 15, S. 1-2, 2005. https://ul.qucosa.de/id/qucosa%3A14303.

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13

Pollet, Benoît. "Transport-reactions dans les membranes echangeuses d'ions : extraction et transport facilites d'acides faibles, cas particulier de l'acide borique." Paris 6, 1987. http://www.theses.fr/1987PA066584.

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Le transport de substrat a travers une membrane echangeuse d'ions peut etre accelere lorsqu'un contre ion joue le role de transporteur. L'acide borique par reaction de neutralisation avec le contre ion hydroxyle et par reaction de condensation avec l'ion borate forme des complexes polyborates (tri-, tetra- et penta-borates) de stabilite moyenne

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14

Lantto, Jonas. "Analytical model of mass transfer through supported liquid membranes." Thesis, KTH, Skolan för kemivetenskap (CHE), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-176912.

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This report details the development and validation of a model for the simulation of supported liquid membrane processes, as applied to the extraction of lanthanides. Supported liquid membranes are systems where two phases, usually aqueous, are separated by a third phase, typically organic, which acts as a membrane, in order to separate solutes from one phase to the other. The model employs an analytical solution to the diffusion equation for the organic phase and linear approximations of the resistances to mass transfer in the aqueous phase boundary layers. The goal of this model is to underline the importance of taking these boundary layer resistances into account.
Detta arbete introducerar, deriverar och evaluerar en matematisk modell för simulering av vätskemembranprocesser, tillämpat på vätskeextraktion av lantanider. Immobiliserade vätskemembran betecknar system där två faser oftast vatten, separeras av en tredje organisk fas som agerar membran för att separera och transportera lösta komponenter från den ena vattenfasen till den andra. Modellen utnyttjar sig av en analytisk lösning till diffusionsekvationen för den organiska fasen och linjära approximationer för motstånden mot masstransport i de båda vattenfasernas gränsskikt. Målet med modellen är att understryka vikten av att inkludera dessa gränsskikt i beräkningarna.

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15

Chihara, Kazuyuki, Takashi Matsumoto, and Kazunori Hijikata. "Azeotropic adsorption of organic solvent vapor mixture on high silica zeolite, mass transfer dynamics." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-194773.

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16

Remi, Julien Cousin Saint, Alexander Lauerer, Gino Baron, Christian Chmelik, Joeri Denayer, and Jörg Kärger. "The effect of crystal diversity of nanoporous materials on mass transfer studies." Diffusion fundamentals 24 (2015) 10, S. 1, 2015. https://ul.qucosa.de/id/qucosa%3A14524.

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17

McCarthy, Kathleen Ann. "The transport of volatile compounds across the capillary fringe /." Full text open access at:, 1992. http://content.ohsu.edu/u?/etd,190.

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18

Heinke, Lars. "Significance of concentration-dependent intracrystalline diffusion and surface permeation for overall mass transfer." Diffusion fundamentals 4 (2007) 12, S. 1-11, 2007. https://ul.qucosa.de/id/qucosa%3A14285.

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The intracrystalline concentration profiles evolving during molecular uptake and release by nanoporous materials as accessible by interference microscopy contain a lot of hidden information. For concentration-independent transport parameter, the influence of surface resistances to overall mass transfer can be calculated by correlating the actual surface concentration with the overall uptake. By using a numerical solution of Fick’s 2nd law and considering a large variety of concentration dependencies of the transport diffusivity and the surface permeability, we show that the factor by which the transport process is retarded by the surface resistance may reasonably well be estimated by the type of correlation between the actual boundary concentration and the total uptake at a given time. In this way, a novel technique of uptake analysis which may analytically be shown to hold for constant diffusivities and surface permeabilities, is shown to be quite generally applicable.

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19

Courthial, Lucile, Arnaud Baudot, Elsa Jolimaitre, Melaz Tayakout, and Christian Jallut. "Moments method applied to the In-Situ characterisation of normal butane mass transfer in MFI zeolite membranes: Moments method applied to the In-Situ characterisation of normalbutane mass transfer in MFI zeolite membranes." Diffusion fundamentals 2 (2005) 88, S. 1-2, 2005. https://ul.qucosa.de/id/qucosa%3A13373.

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20

Li, Zhen. "Transport of reactive solutes in heterogeneous porous media: Heterogeneous rate-limited mass transfer." Diss., The University of Arizona, 2000. http://hdl.handle.net/10150/284040.

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The transport of reactive solutes in the subsurface is influenced by a variety of physical and chemical processes. The processes are characteristically heterogeneous and often operate simultaneously at different temporal and spatial scales. In modeling reactive solute transport different models take different approaches, dependent on the scale of the system and the objective of the study. Two major approaches have been used to incorporate heterogeneous rate-limited mass transfer into mathematical models for solute transport. One focuses on processes operative at the microscopic scale and associated grain-scale heterogeneity, while the other stresses the macroscopic variability of the medium and the field-scale behavior of solute transport. In this work, I first examine the conceptual framework and model formulation of these two approaches in an attempt to evaluate potential commonality, then present a two dimensional numerical model that integrates the first approach with traditional stochastic modeling for reactive transport. In this model multiple processes are explicitly accounted for, including spatially variable flow, spatially variable sorption, locally heterogeneous diffusive mass transfer, locally heterogeneous rate-limited sorption, and locally heterogeneous first-order degradation. Finally, the model is used to (1) examine the individual and concurrent effects of multiple heterogeneous processes on reactive transport, and (2) evaluate the impact of microscopic-scale mass transfer heterogeneity on field-scale transport in systems for which hydraulic conductivity is spatially variable. The comparison of the two approaches shows that despite differences in conceptualization and formulation, both microscopic and macroscopic based models produce comparable behavior for smaller-scale systems. However, greater deviations are observed at larger scales. This suggests that caution should be taken when using mathematical modeling for elucidating the specific processes that may be influencing reactive-solute transport for a given system. Results from 2-D simulations of the new model reveal that inclusion of locally heterogeneous mass transfer does not appear to significantly influence the mean transport behavior for systems with field-scale heterogeneity. However, it does appear to influence low-concentration tailing. For simulations of reactive transport over extended distances, models with locally heterogeneous mass transfer may "preserve" the non-equilibrium effects associated with rate-limited mass transfer better than the models incorporating locally uniform mass transfer when both pore-scale and field-scale heterogeneity coexist.

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21

Courthial, Lucile, Arnaud Baudot, Elsa Jolimaitre, Melaz Tayakout, and Christian Jallut. "Moments method applied to the In-Situ characterisation of normal butane mass transfer in MFI zeolite membranes." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-196464.

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22

Mitchell, William James. "Transport phenomena in viscous flow and particle motion in fluidized beds /." Title page, table of contents and abstract only, 1988. http://web4.library.adelaide.edu.au/theses/09ENS/09ensm682.pdf.

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23

Shaw, Cynthia Kit Man. "Mass transport in mixed conducting perovskite related oxides." Thesis, Imperial College London, 2001. http://hdl.handle.net/10044/1/8380.

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24

Deane, G. B. "The transport of mass and energy in toroidal fusion machines." Thesis, University of Oxford, 1989. https://ora.ox.ac.uk/objects/uuid:c087aa58-7ae2-4f3c-a78e-887f1bca8b76.

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To understand the physical mechanism underlying the cross-field transport of mass and energy in magnetoplasmas is a long-standing problem in fusion research. Woods (1987) has recently developed a second-order transport theory which has been used to explain a number of transport-related phenomena observed in tokamaks. Here, we apply second-order transport theory to the reverse field pinch (RFP) and a phenomenon observed in tokamaks known as 'snakes'. Expressions for the mass and energy confinement times in the RFP, Ï_p and Ï_e, are deduced and agreement with experimental results from HBTX is found. For typical operating conditions the times Ï_p ~ 0.1ms and Ï_e ~ 0.2ms are observed in HBTX. Second-order transport theory predicts Ï_p ~ 0.4ms and Ï_e ~ 0.4ms for this machine. Scaling laws for Î²_p versus Î·_e,Î²_p versus I_Ï and Ï_e versus I_Ï are compared with measurements from HBTX and agree well with observation. Snakes are large density perturbations observed in JET after fuel pellet injection. Typical snakes in JET are remarkably stable and are found to have density decay times longer than predictions based on neoclassical theory (Stringer 1987). After their formation, snakes have even been observed to grow (Weller et al. 1987), which suggests the presence of an inward diffusion mechanism. There is also some evidence for a temperature depression in the snakes region. An explanation of the stability and energy balance in snakes based on second-order transport theory is proposed.

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25

Liao, Jiajun. "Coverage, structure and temperature dependence of anomalous mass transport in the Pb wetting layer on the Si(111) surface /." View abstract or full-text, 2009. http://library.ust.hk/cgi/db/thesis.pl?PHYS%202009%20LIAO.

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26

Hu, Qinhong. "Effect of solute size and mass transfer on transport of contaminants in porous media." Diss., The University of Arizona, 1995. http://hdl.handle.net/10150/187149.

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Miscible displacement experiments were performed with solutes of different size and structure to examine their mass transfer, sorption, and transport in homogeneous and heterogeneous porous media. In homogeneous porous media, the contribution of axial diffusion becomes significant at pore-water velocities less than 0.1 cm/h, and the use of a tracer-derived dispersivity for solutes of different sizes would not be valid in this case. Comparison showed that dispersivities measured with a non-sorbing single-solute solution should be applicable to multi-component systems. Breakthrough curves exhibited both early breakthrough and tailing for solute transport in aggregated, stratified, and macroporous media. The extent of non-ideality was consistent with the impact of solute size on the relative degree of "non-equilibrium" experienced by solutes whose transport is constrained by diffusive mass transfer. Flow-interruption experiments with dual tracers of different size, performed for various interruption times, provided additional evidence regarding the effect of solute size on diffusive mass transfer. The relationship between sorbate structure and rate-limited sorption was examined using the QSAR (quantitative structure-activity relationship) approach for sorption of low-polarity compounds by two soils. The first-order valence molecular connectivity (¹xᵛ), accounting for the size and structure of the solutes, was found to be the best topological descriptor. This supports the contention that rate-limited sorption in these systems is analogous to the polymer diffusion model. Based on this model, the calculated diffusion-length ratios for two soils compare favorably to the values determined from the measured rate data. The synergistic effects of rate-limited sorption and mass transfer in heterogeneous porous media were examined. Independent predictions produced with the multiprocess non-equilibrium model (MPNE) provided very good descriptions of the experimental data for transport of several organic solutes with different solute structures in a saturated aggregated medium. The success of describing the mass transfer, rate-limited sorption, and transport of contaminants has important implications for understanding contaminant transport in the subsurface and for remediation practices of contaminated sites.

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27

Al-Naji, Majd, Michael Goepel, Anca Roibu, and Roger Gläser. "Reduction of p-Nitrophenol to p-Aminophenol over supported monometallic catalysts as a model reaction for mass-transfer investigations." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-197993.

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28

Donato, Adam Armido. "Multiscale Modeling and Uncertainty Quantification of Multiphase Flow and Mass Transfer Processes." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/51246.

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Most engineering systems have some degree of uncertainty in their input and operating parameters. The interaction of these parameters leads to the uncertain nature of the system performance and outputs. In order to quantify this uncertainty in a computational model, it is necessary to include the full range of uncertainty in the model. Currently, there are two major technical barriers to achieving this: (1) in many situations -particularly those involving multiscale phenomena-the stochastic nature of input parameters is not well defined, and is usually approximated by limited experimental data or heuristics; (2) incorporating the full range of uncertainty across all uncertain input and operating parameters via conventional techniques often results in an inordinate number of computational scenarios to be performed, thereby limiting uncertainty analysis to simple or approximate computational models. This first objective is addressed through combining molecular and macroscale modeling where the molecular modeling is used to quantify the stochastic distribution of parameters that are typically approximated. Specifically, an adsorption separation process is used to demonstrate this computational technique. In this demonstration, stochastic molecular modeling results are validated against a diverse range of experimental data sets. The stochastic molecular-level results are then shown to have a significant role on the macro-scale performance of adsorption systems. The second portion of this research is focused on reducing the computational burden of performing an uncertainty analysis on practical engineering systems. The state of the art for uncertainty analysis relies on the construction of a meta-model (also known as a surrogate model or reduced order model) which can then be sampled stochastically at a relatively minimal computational burden. Unfortunately these meta-models can be very computationally expensive to construct, and the complexity of construction can scale exponentially with the number of relevant uncertain input parameters. In an effort to dramatically reduce this effort, a novel methodology "QUICKER (Quantifying Uncertainty In Computational Knowledge Engineering Rapidly)" has been developed. Instead of building a meta-model, QUICKER focuses exclusively on the output distributions, which are always one-dimensional. By focusing on one-dimensional distributions instead of the multiple dimensions analyzed via meta-models, QUICKER is able to handle systems with far more uncertain inputs.
Ph. D.

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29

Inzoli, Isabella, Jean Marc Simon, and Signe Kjelstrup. "Surface resistance to heat and mass transfer in a silicalite membrane: a non-equilibrium molecular dynamics study." Diffusion fundamentals 6 (2007) 22, S. 1-2, 2007. https://ul.qucosa.de/id/qucosa%3A14196.

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30

Rehman, Tauseef ur. "Efficient numerical method for solution of L² optimal mass transport problem." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/33891.

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In this thesis, a novel and efficient numerical method is presented for the computation of the L² optimal mass transport mapping in two and three dimensions. The method uses a direct variational approach. A new projection to the constraint technique has been formulated that can yield a good starting point for the method as well as a second order accurate discretization to the problem. The numerical experiments demonstrate that the algorithm yields accurate results in a relatively small number of iterations that are mesh independent. In the first part of the thesis, the theory and implementation details of the proposed method are presented. These include the reformulation of the Monge-Kantorovich problem using a variational approach and then using a consistent discretization in conjunction with the "discretize-then-optimize" approach to solve the resulting discrete system of differential equations. Advanced numerical methods such as multigrid and adaptive mesh refinement have been employed to solve the linear systems in practical time for even 3D applications. In the second part, the methods efficacy is shown via application to various image processing tasks. These include image registration and morphing. Application of (OMT) to registration is presented in the context of medical imaging and in particular image guided therapy where registration is used to align multiple data sets with each other and with the patient. It is shown that an elastic warping methodology based on the notion of mass transport is quite natural for several medical imaging applications where density can be a key measure of similarity between different data sets e.g. proton density based imagery provided by MR. An application is also presented of the two dimensional optimal mass transport algorithm to compute diffeomorphic correspondence maps between curves for geometric interpolation in an active contour based visual tracking application.

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31

Heinke, Lars, Pavel Kortunov, Despina Tzoulaki, and Jörg Kärger. "The options of interference microscopy to explore the significance of intracrystalline diffusion and surface permeation for overall mass transfer on nanoporous materials." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-194002.

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32

BORGES, ANDREA FERREIRA. "NUMERICAL MODELLING OF TWO-PHASE FLOW AND TRANSPORT IN POROUS MEDIA WITH MASS TRANSFER AND COSOLVENCY." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2002. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=5960@1.

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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
Neste trabalho foi desenvolvido um programa para simulação numérica do fluxo bifásico em meios porosos com transferência de massa entre as duas fases e transporte dos solutos em cada fase. O programa calcula o aumento da mobilidade da fase não aquosa e da solubilidade de seus componentes na água como resultado da adição de um co- solvente. O objetivo foi simular problemas de contaminação no subsolo com líquidos imiscíveis com a água e a remediação através da técnica de injeção de co-solventes, assim como a contaminação a partir de vazamentos de gasolina acrescida de álcool em postos de abastecimento. Podem-se ainda resolver problemas de fluxo bifásico envolvendo uma fase gasosa. Foi desenvolvido e implementado um modelo para a transferência de massa durante o fluxo das duas fases. O cálculo das propriedades das duas fases ao longo do tempo é feito utilizando o diagrama ternário de fases. Para resolver as equações do fluxo e do transporte de solutos foi empregado o método de elementos finitos.
A computer code was developed for numerical simulation of two-phase flow in porous media considering mass transfer between the phases involved and solute transport in each phase. Enhanced mobility of nonaqueous phase and enhanced aqueous solubility of its components as a result of cosolvent injection are calculated. The objective of this work was to simulate subsurface contamination by nonaqueous phase liquids and remediation utilizing cosolvent injection technique, and also contamination by gasoline with alcohol from fuel tanks. It is also possible to solve two-phase flow problems involving a gaseous phase. A model for mass transfer during two-phase flow was developed and implemented. Properties variation with time for both phases is calculated using ternary phase diagram. Finite element method was used to solve flow and solute transport equations.

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33

Mielke, Eric. "Study on the Transport Phenomena in Complex Micro-Reactors." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36040.

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Continuous processing in the pharmaceutical and fine chemical industries, particularly in micro/milli-scale reactors, has been a topic of interest in literature in recent years due to the advantages offered over batch reactions. One such advantage is the enhanced transport properties of operating at smaller scales, although the quantification of the transport phenomena is not straightforward when wall and entrance effects cannot be neglected. In the first study presented, various micro-mixer geometries and scales were considered to increase the mixing efficiency in liquid-liquid systems of diverse interfacial tensions for fast reactions. The conditions were varied over different flow regimes; including slug flow, parallel flow, and drop flow. A mass-transfer-limited test reaction was used to evaluate the overall volumetric mass transfer coefficients (Korga) as a function of the average rate of energy dissipation (ε) for each mixer design. The onset of drop flow occurred at a lower ε for the LL-Triangle mixer when compared with the Sickle or LL-Rhombus mixers for low interfacial-tension systems (i.e., n-butanol-water). In the drop flow regime for energy dissipation rates of around 20 to 500 W/kg, Korga values ranged from approximatively 0.14 to 0.35 s-1 and 0.004 to 0.015 s-1 for the relatively low and high interfacial-tension (i.e., toluene-water) systems, respectively. The second investigation explored the heat transfer properties of a FlowPlate® system by Ehrfeld Mikrotechnik BTS. First, in a non-reactive system with rectangular serpentine channels (d_h<1mm, 400

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34

Nechaev, Yury S. "Anomalies of the diffusion mass-transfer during 2D-decomposition of superconducting YBa 2 Cu 3 O 6+X /Y 2 BaCuO 5 composites." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-196070.

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35

Garyfalou, Aikaterini. "Integrated analysis of mass transport deposits : outcrop data, seismic interpretation & fast Fourier transform analysis." Thesis, University of Aberdeen, 2015. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=227755.

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36

Nechaev, Yury S. "Anomalies of the diffusion mass-transfer during 2D-decomposition of superconducting YBa 2 Cu 3 O 6+X /Y 2 BaCuO 5 composites: Anomalies of the diffusion mass-transfer during 2D-decompositionof superconducting YBa 2 Cu 3 O 6+X /Y 2 BaCuO 5 composites." Diffusion fundamentals 2 (2005) 54, S. 1-2, 2005. https://ul.qucosa.de/id/qucosa%3A14387.

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37

Fernandes, Mariana. "Proposta e comparação de um modelo fenomenológico com base em alto transporte de massa e supersaturação para torre de resfriamento de água." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/3/3137/tde-27032012-114749/.

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Torres de resfriamento são equipamentos muito utilizados na indústria e que muitas vezes operam sob condições adversas, particularmente, temperatura de água acima dos 50°C na entrada da torre. Nesta condição, tem-se alta taxa de evaporação e eventualmente condição de alto transporte de massa, normalmente não considerado no equacionamento de torres de resfriamento. Apresenta-se assim uma análise comparativa de diferentes métodos de cálculo de torres de resfriamento: Merkel, Poppe e o modelo proposto. No modelo proposto neste estudo, consideram-se os balanços diferenciais de massa e energia e os mecanismos de transporte simultâneo de calor e massa, na condição de alto transporte de massa e de supersaturação do ar, caso o vapor de água condense na forma de névoa. Para os casos em que há saturação do ar, os balanços diferenciais de massa e energia passam a contemplar este fenômeno a partir do momento em que ocorre a saturação. O modelo matemático desenvolvido consiste de equações diferenciais ordinárias e equações auxiliares, e foi implementado em uma interface Matlab. Os principais parâmetros investigados foram: as vazões de água e ar, a temperatura de bulbo úmido do ar, a temperatura da água na entrada da coluna e a altura da torre. A partir das simulações matemáticas, foram obtidos resultados de temperaturas do ar, da água e da umidade do ar ao longo da coluna, para os diferentes métodos.
Cooling towers are equipment widely used in industrial plants, where these operate under severe conditions such as cooling water inlet temperatures above 50oC. Under this condition, there are high evaporation of water and high mass transfer, generally not considered in performance analysis of a cooling tower. This work presents and analyzes the differences between the proposed model and the Merkel and Poppe approaches. The proposed model in this work is based on differential equations for energy and mass balances and on the mechanisms of combined heat and mass transfers, at high mass transfer condition and considering the supersaturated air from the height of the tower that the excess of water vapor condenses as a mist. At the point that the air became supersaturated, the differential equations for energy and mass balances start to consider the supersaturation phenomena. The mathematical model developed in this work is composed by ordinary differential equations and auxiliary equations which were solved at Matlab. The parameters investigated were water and air mass flow rates, air wet bulb temperature, water inlet temperature and tower height. The results of air and water temperatures, humidity air across the tower height are presented for each method analyzed.

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38

Godongwana, Buntu. "Effect of nutrient momentum and mass transport on membrane gradostat reactor efficiency." Thesis, Cape Peninsula University of Technology, 2016. http://hdl.handle.net/20.500.11838/2149.

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Thesis submitted in fulfilment of the requirements for the degree Doctor technologiae (engineering: chemical) In the faculty of engineering at the cape peninsula university of technology
Since the first uses of hollow-fiber membrane bioreactors (MBR’s) to immobilize whole cells were reported in the early 1970’s, this technology has been used in as wide ranging applications as enzyme production to bone tissue engineering. The potential of these devices in industrial applications is often diminished by the large diffusional resistances of the membranes. Currently, there are no analytical studies on the performance of the MBR which account for both convective and diffusive transport. The purpose of this study was to quantify the efficiency of a biocatalytic membrane reactor used for the production of enzymes. This was done by developing exact solutions of the concentration and velocity profiles in the different regions of the membrane bioreactor (MBR). The emphasis of this study was on the influence of radial convective flows, which have generally been neglected in previous analytical studies. The efficiency of the MBR was measured by means of the effectiveness factor. An analytical model for substrate concentration profiles in the lumen of the MBR was developed. The model was based on the solution of the Navier-Stokes equations and Darcy’s law for velocity profiles, and the convective-diffusion equation for the solute concentration profiles. The model allowed for the evaluation of the influence of both hydrodynamic and mass transfer operating parameters on the performance of the MBR. These parameters include the fraction retentate, the transmembrane pressure, the membrane hydraulic permeability, the Reynolds number, the axial and radial Peclet numbers, and the dimensions of the MBR. The significant findings on the hydrodynamic studies were on the influence of the fraction retentate. In the dead-end mode it was found that there was increased radial convective flow, and hence more solute contact with the enzymes/biofilm immobilised on the surface of the membrane. The improved solute-biofilm contact however was only limited to the entrance half of the MBR. In the closed shell mode there was uniform distribution of solute, however, radial convective flows were significantly reduced. The developed model therefore allowed for the evaluation of an optimum fraction retentate value, where both the distribution of solutes and radial convective flows could be maximised.

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39

Al-Naji, Majd, Michael Goepel, Anca Roibu, and Roger Gläser. "Reduction of p-Nitrophenol to p-Aminophenol over supported monometallic catalysts as a model reaction for mass-transfer investigations: Reduction of p-Nitrophenol to p-Aminophenol over supportedmonometallic catalysts as a model reaction for mass-transferinvestigations." Diffusion fundamentals 24 (2015) 2, S. 1, 2015. https://ul.qucosa.de/id/qucosa%3A14515.

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Chen, Hua. "Investigation of Contaminant Transport in Tidally-Influenced Aquifers: Experiment and Analysis." ScholarWorks @ UVM, 2010. http://scholarworks.uvm.edu/graddis/43.

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Tidally-induced head fluctuation is a natural phenomenon in coastal regions. The discharge of groundwater through sediments will occur anywhere that the aquifer is hydraulically connected to a surface water body and the time averaged tidally-influenced water level in the aquifer is higher than sea level, and almost all coastal regions are subject to such flow. With the development of coastal areas, the discharge of groundwater contaminants into tidally affected coastal water bodies has become a significant problem. Biota that live in the benthic region are known to be sensitive to the concentration of discharging anthropogenic chemical compounds. Thus the contaminant concentration entering the benthos is of very significant practical importance and its study is the focus of this dissertation. An investigation of the effect of tides on the concentration of groundwater contaminants discharging to a surface water body is studied using a one-dimensional homogeneous sand column. Results of the experiment are confirmed using a three-dimensional heterogeneous groundwater tank model. A constant water level is imposed upgradient, and the downgradient water level is controlled by a wave generator that controls the hydraulic head to mimic a 12 hour tidal fluctuation. The experimental results demonstrate that the tidal fluctuations in the downgradient reservoir result in a decrease in average contaminant concentration at the point of groundwater discharge to the surface-water body. The further upstream the well is located, the smaller the amplitude of the concentration oscillation. In addition, upstream migration of concentration oscillations is observed in spite of a net downgradient flow. Fourier analysis suggests that the dominant frequency of the peaks of pressure and chemical data at different locations along the length of the column is identically two cycles per day and that the amplitudes of the concentration oscillations increase with time at measurement locations at the upstream responding probes. As the classical groundwater flow and transport model cannot reproduce the phenomena we observed, an innovative multi-mobility model, is proposed with one highly mobile liquid phase, one less mobile liquid phase and a solid phase. Averaging theory is applied to develop the mass conservation equation from the microscale to the macroscale and facilitate the reduction of dimensionality to obtain one-dimensional governing equations with closure relations. A new finite volume method is utilized to solve the resulting equations. The simulation confirms the existence of the enhanced tidally-induced mixing process.

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Gonzalez-Pena, Omar Israel. "Mass Transport Enhancement in Copper Electrodeposition due to Gas Co-Evolution." Case Western Reserve University School of Graduate Studies / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=case1439826379.

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Bhopte, Siddharth. "Study of transport processes from macroscale to microscale." Diss., Online access via UMI:, 2009.

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Thesis (Ph. D.)--State University of New York at Binghamton, Thomas J. Watson School of Engineeering and Applied Science, Department of Mechanical Engineering, 2009.
Includes bibliographical references.

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Nelson, George J. "Computational characterization of diffusive mass transfer in porous solid oxide fuel cell components." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31660.

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Thesis (Ph.D)--Mechanical Engineering, Georgia Institute of Technology, 2010.
Committee Co-Chair: Haynes, Comas; Committee Co-Chair: Wepfer, William; Committee Member: Fedorov, Andrei; Committee Member: Liu, Meilin; Committee Member: Paredis, Chris; Committee Member: Teja, Amyn. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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44

Bielinski, Clément. "Impact of the flow on mass transfer from particles : biomedical applications." Thesis, Compiègne, 2021. https://bibliotheque.utc.fr/Default/doc/SYRACUSE/2021COMP2630.

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Le transfert de masse à partir de particules présente de nombreuses applications biomédicales, telles que le relargage contrôlé de médicaments, la culture cellulaire, ou encore la conception d’organes bioartificiels. En conditions opérationnelles, les particules sont soumises à des écoulements de fluides de différentes natures, dont l’effet sur le transport du soluté est aujourd’hui encore mal connu. Dans cette thèse, nous nous intéressons à l’effet de l’écoulement sur le transfert de masse à partir de capsules et de fibres cœur-coque. Le cas du relargage d’un soluté par une fibre cœur-coque confinée dans un canal plan et soumise à un écoulement de Poiseuille est étudié à partir de simulations numériques en deux dimensions basées sur la méthode de Boltzmann sur réseau. Les effets combinés de l’écoulement et de la présence de la coque sur le transfert de masse sont analysés sur une large plage de nombre de Reynolds couvrant des écoulements stationnaires et instationnaires. Une corrélation donnant le nombre de Sherwood (le coefficient de transfert de masse adimensionnel) en fonction de la perméabilité de la coque, du nombre de Reynolds, et du nombre de Schmidt est proposée. La perméabilité de la coque est une propriété difficilement mesurable. Les méthodes actuelles de caractérisation ne permettent d’obtenir qu’une perméabilité effective pour l’ensemble de la particule (cœur et coque réunis), et non spécifiquement pour la coque. Une nouvelle méthode de caractérisation est proposée et validée sur des données numériques et expérimentales. Cette méthode consiste à extraire la perméabilité de la capsule par analyse inverse, en ajustant les courbes de relargage avec des solutions de la seconde loi de Fick calculées en une dimension par la méthode des différences finies. Le relargage d’un soluté par une capsule placée dans un écoulement de cisaillement est également analysé par des simulations tridimensionnelles couplant la méthode de Boltzmann sur réseau et la méthode des frontières immergées pour les interactions fluides-structure. L’écoulement améliore significativement l’efficacité du transfert de masse par convection forcée. L’effet des conditions aux limites à la surface de la capsule est examiné. Considérer des conditions aux limites de Dirichlet, comme fait classiquement dans la littérature, conduit à des nombres de Sherwood bien plus élevés que dans le cas de conditions aux limites de continuité, plus adaptées pour modéliser le relargage d’un soluté. La dynamique d’une suspension de capsules déformables en écoulement dans une constriction est aussi étudiée. Un diagramme d’états décrivant la transition entre le passage et le blocage de la constriction par les capsules est déterminé en fonction de leurs propriétés géométriques et mécaniques. Il peut être utilisé, par exemple, afin d’optimiser le design de systèmes microfluidiques dans le but d’améliorer l’efficacité du transfert de masse
Mass transfer from particles is encountered in many biomedical applications, such as controlled drug delivery, cell culture, or in designing bioartificial organs. In operating conditions, particles are subjected to various flows, whose effect on solute transport is still not well understood and controlled. In this PhD thesis, we study the effect of the flow on mass transfer from core-shell capsules and fibers, using numerical simulations. Solute release from a core-shell fiber confined in a channel and subjected to Poiseuille flow is studied using two-dimensional lattice Boltzmann simulations. The combined effects of the flow and the shell permeability on mass transfer are analyzed over a wide range of Reynolds number covering both steady and unsteady flows. A new correlation giving the Sherwood number (the dimensionless mass transfer coefficient) as a function of the shell permeability, the Reynolds number, and the Schmidt number is proposed. The shell permeability is difficult to measure. Current characterization methods only allow the determination of an effective permeability for the whole particle (core and shell combined), and not specifically the shell permeability. A novel method to characterize capsules shell permeability is proposed and validated on both numerical and experimental data. This method consists in extracting the capsule permeability by fitting the release curves with numerical solutions of Fick’s second law of diffusion computed in one dimension using the finite difference method, by assuming spherical symmetry. Solute release from a capsule placed in a shear flow is also analyzed by the mean of three-dimensional simulations coupling the lattice Boltzmann method and the immersedboundary method for the fluid-structure interaction. The flow is found to enhance the masstransfer efficiency by forced convection. The effect of the boundary conditions set at the surface of the capsule is examined, as well. Considering Dirichlet boundary conditions at the particle surface, as classically done in literature, leads to significantly higher Sherwood numbers as compared to the case of continuity of both the concentration and the mass flux, which is more adapted to model solute release. The suspension dynamics of soft capsules in a microfluidic constriction is also studied. A state diagram describing the transition from capsule passage to blockage is determined as a function of their geometrical and mechanical properties. It can be used, for example, to optimize the design of microfluidic devices in order to enhance the mass transfer efficiency

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Charrière, Boris. "Modélisation et simulation d'écoulements turbulents cavitants avec un modèle de transport de taux de vide." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAI108/document.

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La simulation numérique des écoulements turbulents cavitants revêt de nombreuses difficultés tant dans la modélisation des phénomènes physiques que dans le développement de méthodes numériques robustes. En effet de tels écoulements sont caractérisés par un changement de phase associé à des gradients de la masse volumique, des variations du nombre de Mach causées par une chute de la vitesse du son, des zones de turbulence diphasique et la présence d'instationnarités.Les travaux de la présente thèse s'inscrivent dans la continuité des études expérimentales et numériques menées au sein du Laboratoire des Ecoulements Géophysiques et Industriels (LEGI),qui visent à améliorer la compréhension et la modélisation d'écoulements cavitants. Les simulations s'appuient sur un code compressible associé à une technique de pré-contionnement bas-Mach qui permet de traiter les zones incompressibles. Les écoulements diphasiques sont reproduits à l'aide d'un modèle de mélange homogène 1-fluide avec discrétisation implicite en pas de temps dual. Enfin la résolution adopte l'approche moyennée RANS qui couple le système des équations de conservation avec des modèles de turbulence du premier ordre basés sur la notion de viscosité turbulente.Dans les zones diphasiques, le calcul des variables thermodynamiques nécessite l'introduction d'équations d'état. La pression au sein du mélange est ainsi reliée aux grandeurs conservatives soit à partir d'une équation d'état de mélange des gaz raides, soit par une relation sinusoïdale incorporant la fraction volumique de vapeur (le taux de vide). La valeur ajoutée de ces travaux de thèse repose sur l'introduction d'une équation de transport pour le calcul du taux de vide. Celle-ci incorpore un terme source dont le transfert de masse entre les phases est fermé grâce à une hypothèse de proportionnalité à la divergence du champ de vitesse. Outre l'amélioration des phénomènes de convection, de dilatation et de collapse, cette équation supplémentaire permet de relaxer l'équilibre thermodynamique local et d'introduire un état métastable pour la phase vapeur.Les simulations 2D et 3D sont réalisées sur des géométries de type Venturi caractérisées par le développement de poches de cavitation partielle instables. L'objectif consiste à reproduire les instationnarités inhérentes à chaque profil telles que la formation d'un jet rentrant liquide à proximité de la paroi ou la production de nuages de vapeur convectés par l'écoulement principal.Les résultats numériques mettent en avant une variation de la fréquence des instationnarités en fonction du calcul de la vitesse du son en zone de mélange. D'autre part, la prise en compte de déséquilibre de la phase vapeur amplifie les phénomènes de propagation d'ondes de pression générées par le collapse des structures cavitantes et participe à la déstabilisation de la poche. Enfin, l'influence de l'équation de transport de taux de vide est analysée en confrontant les résultats des simulations à ceux obtenus ultérieurement à partir d'un modèle à seulement trois équations de conservation
The computation of turbulent cavitating flows involves many difficulties both in modeling the physical phenomena and in the development of robust numerical methods. Indeed such flows are characterized by phase transitions and large density gradients, Mach number variation due to speed of sound decrease, two-phase turbulent areas and unsteadiness.This thesis follows experimental and numerical studies led at the Laboratoire des Ecoulements Géophysiques et Industriels which aim to improve the understanding and modeling of cavitating flows. Simulations are based on a compressible code coupled with a pre-conditionning technique which handles low-Mach number areas. The two-phase flows are reproduced using a one-fluid homogeneous model and temporal discretisation is performed using an implicit dual-time stepping method . The resolution is based on the RANS approach that couples conservation equations with firts-order closure models to compute eddy viscosity.In two-phase flows areas, the computation of thermodynamic quantities requires to close the system with equations of state (EOS). Thus, two formulations are investigated to determine the pressure in the mixture. The stiffened gas EOS is written with conservative quantities while a sinusoidal law deduces the pressure from the volume fraction of vapor (the void fraction). The present study improves the homogeneous equilibrium models by including a transport equation for the void ratio. The mass transfer between phases is assumed to be proportional to the divergence of the velocity. In addition to a better modeling of convection, expansion and collapse phenomenon, this added transport equation allows to relax the local thermodynamic equilibrium and to introduce a mestastable state to the vapor phase.2D and 3D simulations are performed on Venturi type geometries characterized by the development of unstable partial cavitation pockets. The goal is to reproduce unsteadiness linked to each profile such as the formation of a re-entrant jet or the quasi-periodic vapor clouds shedding. Numerical results highlight frequency variations of unsteadiness depending on the speed of sound computation. Moreover, the simulation conducted with a relaxed vapor density increase the pressure wave propagation magnitude generated by the collapse of cavitating structures. It contributes to the destabilization of the pocket. Finally, the role of the void ratio equation is analyzed by comparing the simulation results to those obtained subsequently from a model involving only three conservation equations

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46

Skoglund, Emil. "A NUMERICAL MODEL OF HEAT- AND MASS TRANSFER IN POLYMER ELECTROLYTE FUEL CELLS : A two-dimensional 1+1D approach to solve the steady-state temperature- and mass- distributions." Thesis, Mälardalens högskola, Framtidens energi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-55223.

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Methods of solving the steady state characteristics of a node matrix equation system over a polymer electrolyte fuel cell (PEFC) were evaluated. The most suitable method, referred to as the semi-implicit method, was set up in a MATLAB program. The model covers heat transfer due to thermal diffusion throughout the layers and due to thermal advection+diffusion in the gas channels. Included mass transport processes cover only transport of water vapor and consist of the same diffusion/advection schematics as the heat transfer processes. The mass transport processes are hence Fickian diffusion throughout all the layers and diffusion+advection in the gas channels. Data regarding all the relevant properties of the layer materials were gathered to simulate these heat- and mass transfer processes.Comparing the simulated temperature profiles obtained with the model to the temperature profiles of a previous work’s model, showed that the characteristics and behavior of the temperature profile are realistic. There were however differences between the results, but due to the number of unknown parameters in the previous work’s model it was not possible to draw conclusions regarding the accuracy of the model by comparing the results.Comparing the simulated water concentration profiles of the model and measured values, showed that the model produced concentration characteristics that for the most part alignedwell with the measurement data. The part of the fuel cell where the concentration profile did not match the measured data was the cathode side gas diffusion layer (GDL). This comparison was however performed with the assumption that relative humidity corresponds to liquid water concentration, and that this liquid water concentration is in the same range as the measured data. Because of this assumption it was not possible to determine the accuracy of the model.

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47

Lopes, Gustavo Henndel. "On the coupling of membrane transport to hydrodynamics and bulk mass transfer in reverse osmosis : numerical modeling and experimental studies." Thesis, Ecole centrale de Marseille, 2014. http://www.theses.fr/2014ECDM0013/document.

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La prédiction des performances des séparations membranaires barométriques, fortement affectées par la polarisation de concentration, serait une avancée importante pour le dimensionnement et l’optimisation des procédés. Dans ce contexte, les équations couplées de Navier-Stokes et de conservation du soluté adimensionnées sont résolues numériquement dans le cas d’un écoulement stationnaire laminaire en filtration tangentielle. Le canal plan bidimensionnel comporte des parois perméables soumises à des conditions aux limites du type solubilisation-diffusion. Le flux de perméat, le taux de rétention et le débit, la concentration et la chute de pression du rétentat sont déterminés localement. Les simulations soulignent l’influence des perméabilités membranaires au soluté et au solvant sur la polarisation de concentration et la dépendance non-asymptotique du taux de rétention avec la pression appliquée. Le modèle est validé pour des modules plans et spiralés d’osmose inverse et de nanofiltration dense en comparant les calculs à des résultats expérimentaux tirés de la littérature et de nos propres essais pilotes de dessalement. Aussi, une méthode à l’échelle de la paillasse permettant de déterminer les perméabilités au soluté et au solvant par des expériences d’osmose et diffusion est développée et appliquée à des membranes d’osmose inverse et de nanofiltration. La divergence des mécanismes de transfert engendrés sous l’influence de la pression ou sous l’influence d’un gradient osmotique est mise en évidence. Le modèle numérique et la méthode expérimentale sont des outils prometteurs d’applicabilité immédiate dans le domaine des membranes
The prediction of the performance of pressure-driven membrane separations, deeply affected by concentration polarization, would be an important advance for process design and optimization. In this context, the dimensionless coupled Navier-Stokes and solute conservation equations are solved numerically for a steady laminar cross-flow filtration. The two-dimensional flat channel consists of permeable walls subject to solution-diffusion boundary conditions. The permeate flux, the rejection rate and the retentate’s flow rate, concentration and pressure drop are determined locally. The simulations highlight the influence of the membrane solute and solvent permeabilities on concentration polarization and the non-asymptotic dependence of the rejection rate on the applied pressure. The model is validated for reverse osmosis and tight-nanofiltration plate-and-frame and spiral-wound modules by comparison to experimental results from the literature and from our own pilot desalination tests. Furthermore, a bench-scale method enabling the determination of solute and solvent permeabilities from osmotic-diffusive experiments is developed and applied to reverse osmosis and nanofiltration membranes. The divergence between the transport mechanisms engendered by pressure and by an osmotic gradient is evidenced. The numerical model and the experimental method are new promising tools with immediate applicability in the membrane field

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48

Fauré, Marie-Hélène. "Migration de particules et solutés en milieu poreux : modélisation du transport simultané de particules argileuses et de radionucléides sous l'effet d'un gradient de salinité." Vandoeuvre-les-Nancy, INPL, 1994. http://www.theses.fr/1994INPL046N.

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La compréhension des mécanismes qui contrôlent le transport de particules et de radionucléides dans les milieux poreux naturels ou artificiels est un élément clé dans l'évaluation de la sureté des sites de stockage de déchets radioactifs. Une étude expérimentale a été entreprise afin de caractériser la mobilité des particules argileuses d'un milieu non consolidé sable-bentonite 5% placé dans une colonne de laboratoire au contact d'une solution saline percolante. Une méthode originale de chromatographie de gradient de salinité a permis de mettre en évidence et de quantifier des comportements types: existence de seuils de déstabilisation des particules, apparition de chemins préférentiels, formation de zones stagnantes qui échangent avec l'eau en écoulement. L’approche modélisatrice a consisté à prendre en compte une loi de distribution des particules entre la surface du milieu poreux et la phase aqueuse au contact du solide, fonction de la concentration de chlorure de sodium. Cette fonction de distribution couplée d'une part avec un modèle d'adsorption des radionucléides et d'autre part avec un modèle de transport type convectif dispersif avec zones stagnantes, a permis de simuler le transport de solutés et de particules lors d'une modification des conditions de l'environnement salin. Le modèle a été validé sur des expériences d'injections transitoires de césium, calcium, neptunium, dans un gradient de chlorure de sodium

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Abada, Fella. "Transport d'humidité en matériaux poreux en présence d'un gradient de température : caractérisation expérimentale." Université Joseph Fourier (Grenoble), 1994. http://www.theses.fr/1994GRE10135.

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Ce travail de these porte sur des etudes experimentales relatives aux transferts monodimensionnels d'humidite sous differents gradients thermiques dans des materiaux poreux qui sont: le beton autoclave non expanse, la vermiculite, deux roches extraites de carrieres (rouffach et rorschach) servant a la restauration de monuments historiques. Un dispositif experimental est utilise pour le suivi continu des evolutions de teneurs en eau (methode gammametrique) et de temperatures (sondes thermiques) durant des essais de condensation et de sechage. L'objectif principal de ce travail est la determination des coefficients de transfert pour chaque materiau, determination basee sur la theorie classique du transfert de masse et de chaleur de de vries. Les coefficients de transfert sont calcules par un procede de regression entre les variables mesurees: flux de masse, gradient de temperature et gradient de teneur en eau, on donne leurs evolutions avec la teneur en eau et pour differentes temperatures. D'autres experiences sont aussi realisees donnant les conductivites thermiques et les isothermes d'adsorption permettant, ainsi, d'acquerir des informations sur le comportement des materiaux vis a vis du transfert de chaleur et de vapeur d'eau

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Rahman, Mohammad Mahbubur. "Microscale modelling of cellular level transport and deformation during food drying." Thesis, Queensland University of Technology, 2018. https://eprints.qut.edu.au/120676/1/Mohammad%20Mahbubur_Rahman_Thesis.pdf.

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This thesis contributed to the development of a microscale drying model to predict the actual moisture distribution and physical quality of food material during the drying process. This research has developed a novel methodology to create realistic cellular geometry from microscopic images of food material which can be used as an exact computational domain for the microscale drying model. The model developed is capable of predicting of the cellular level transport and the anisotropic deformation of food material during the drying. The results obtained from the model were validated against extensive experimental investigations.

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