Articoli di riviste: "Transport/ mass transfer"

1

Moore, J. A., e C. R. Ethier. "Oxygen Mass Transfer Calculations in Large Arteries". Journal of Biomechanical Engineering 119, n. 4 (1 novembre 1997): 469–75. http://dx.doi.org/10.1115/1.2798295.

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The purpose of this study was to model the transport of oxygen in large arteries, including the physiologically important effects of oxygen transport by hemoglobin, coupling of transport between oxygen in the blood and in wall tissue, and metabolic consumption of oxygen by the wall. Numerical calculations were carried out in an 89 percent area reduction axisymmetric stenosis model for several wall thicknesses. The effects of different boundary conditions, different schemes for linearizing the oxyhemoglobin saturation curve, and different Schmidt numbers were all examined by comparing results against a reference solution obtained from solving the full nonlinear governing equations with physiologic values of Schmidt number. Our results showed that for parameters typical of oxygen mass transfer in the large arteries, oxygen transport was primarily determined by wall-side effects, specifically oxygen consumption by wall tissue and wall-side mass transfer resistance. Hemodynamic factors played a secondary role, producing maximum local variations in intimal oxygen tension on the order of only 5–6 mmHg. For purposes of modeling blood-side oxygen transport only, accurate results were obtained through use of a computationally efficient linearized form of the convection-diffusion equation, so long as blood-side oxygen tensions remained in the physiologic range for large arteries. Neglect of oxygen binding by hemoglobin led to large errors, while arbitrary reduction of the Schmidt number led to more modest errors. We conclude that further studies of oxygen transport in large arteries must couple blood-side oxygen mass transport to transport in the wall, and accurately model local oxygen consumption within the wall.

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Speetjens, M. F. M., e A. A. Van Steenhoven. "Heat and Mass Transfer Made Visible". Defect and Diffusion Forum 312-315 (aprile 2011): 713–18. http://dx.doi.org/10.4028/www.scientific.net/ddf.312-315.713.

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Heat and mass transfer in fluid flows traditionally is examined in terms of temperature and concentration fields and heat/mass-transfer coefficients at fluid-solid interfaces. However, heat/mass transfer may alternatively be considered as the transport of a passive scalar by the total advective-diffusive flux in a way analogous to the transport of fluid by the flow field. This Lagrangian approach facilitates heat/mass-transfer visualisation in a similar manner as flow visualisation and has great potential for transport problems in which insight into (interaction between) the scalar fluxes throughout the entire configuration is essential. This ansatz furthermore admits investigation of heat and mass transfer by well-established geometrical methods from laminar-mixing studies, which offers promising new research capabilities. The Lagrangian approach is introduced and demonstrated by way of representative examples.

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Ndiaye, L., Mb Ndiaye, A. Sy e D. Seck. "Pollution Transfer as Optimal Mass Transport Problem". Journal of Mathematics Research 8, n. 6 (25 novembre 2016): 58. http://dx.doi.org/10.5539/jmr.v8n6p58.

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In this paper, we use mass transportation theory to study pollution transfer in porous media. We show the existence of a $L^2-$regular vector field defined by a $W^{1, 1}-$ optimal transport map. A sufficient condition for solvability of our model, is given by a (non homogeneous) transport equation with a source defined by a measure. The mathematical framework used, allows us to show in some specifical cases, existence of solution for a nonlinear PDE deriving from the modelling. And we end by numerical simulations.

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Mujumdar, A. S. "Transport Phenomena in Heat and Mass Transfer". Drying Technology 11, n. 7 (gennaio 1993): 1917–18. http://dx.doi.org/10.1080/07373939308916939.

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Levdansky, Valerij, Olina Šolcová, Karel Friess e Pavel Izák. "Mass Transfer Through Graphene-Based Membranes". Applied Sciences 10, n. 2 (8 gennaio 2020): 455. http://dx.doi.org/10.3390/app10020455.

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The problems related to the transport of gases through nanoporous graphene (NG) and graphene oxide (GO) membranes are considered. The influence of surface processes on the transport of gas molecules through the aforementioned membranes is studied theoretically. The obtained regularities allow finding the dependence of the flux of the gas molecules passing through the membrane on the kinetic parameters which describe the interaction of the gas molecules with the graphene sheets. This allows to take into account the influence of external fields (e.g., resonance radiation), affecting the aforementioned kinetic parameters, on the transport of gas molecules through the membranes. The proposed approach makes it possible to explain some experimental results related to mass transfer in the GO membranes. The possibility of the management of mass transfer through the NG and GO membranes using resonance radiation is discussed.

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Geary, Denis F., Elizabeth A. Harvey e J. Williamson Balfe. "Mass Transfer Area Coefficients in Children". Peritoneal Dialysis International: Journal of the International Society for Peritoneal Dialysis 14, n. 1 (gennaio 1994): 30–33. http://dx.doi.org/10.1177/089686089401400106.

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Objective Measurement of mass transfer area coefficients (MTAC) in children of different sizes to determine if solute transport varies with age and to compare with published adult values. Design Mass transfer area coefficients calculated from prospectively collected data in 28 selected patients. Participants All children starting maintenance peritoneal dialysis at the Hospital for Sick Children. Selected patients were also studied if hospitalized for unrelated reasons. Results Mean MTAC values for creatinine and glucose were 4.0 and 4.5 mL/min, respectively, both considerably lower than adult values. When scaled per 70 kg body weight, these results were greater, and when scaled per 1.73 m2 surface area, they were lower than reported adult values. The MTAC/kg body weight was inversely correlated to age. Conclusions Solute transport in children is directly related to age and does not approach adult values until later childhood. However, more rapid transport per unit body weight is observed in children and may reflect an increased effective peritoneal surface area.

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Boskovic-Vragolovic, Nevenka, Radmila Garic-Grulovic e Zeljko Grbavcic. "Wall-to-liquid mass transfer in fluidized beds and vertical transport of inert particles". Journal of the Serbian Chemical Society 72, n. 11 (2007): 1103–13. http://dx.doi.org/10.2298/jsc0711103b.

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Mass transfer coefficients in single phase flow, liquid fluidized beds and vertical hydraulic transport of spherical inert particles were studied experimentally using 40 mm and 25.4 mm diameter columns. The mass transfer data were obtained by studying the transfer of benzoic acid from a tube segment to water using the dissolution method. In all runs, the mass transfer rates were determined in the presence of spherical glass particles 1.2, 1.94 and 2.98 mm in diameter. The influence of different parameters, such as liquid velocity, particles size and voids on mass transfer in fluidized beds and hydraulic transport are presented. The data for mass transfer in all the investigated systems are shown using the Sherwood number (Sh) and mass transfer factor - Colburn factor (jD) - as a function of Reynolds number (Re) for the particles and for the column. The data for mass transfer in particulate fluidized beds and for vertical hydraulic transport of spherical particles were correlated by treating the flowing fluid-particle mixture as a pseudo fluid by introducing a modified mixture Reynolds number (Rem). A new correlation for the mass transfer factor in fluidized beds and in vertical hydraulic transport is proposed.

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Wäsche, S., H. Horn e D. C. Hempel. "Mass transfer phenomena in biofilm systems". Water Science and Technology 41, n. 4-5 (1 febbraio 2000): 357–60. http://dx.doi.org/10.2166/wst.2000.0466.

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Mathematical models allow the simulation of microorganism growth and substrate transport in biofilm systems. Nevertheless there is still a lack of knowledge about the mass transfer of substrate in the boundary layer between biofilm and bulkphase. Several biofilms were cultivated under different substrate and hydrodynamic conditions in a biofilm tube reactor. Oxygen concentration profiles were measured with oxygen microelectrodes in the biofilm and in the boundary layer. The thickness of the concentration layer was found to depend on surface structure which depends on the substrate loading and the hydrodynamic conditions during the growth phase of the biofilm. Biofilm density and maximum substrate flux were also influenced by growth conditions. An empirical function for the concentration layer thickness was formulated for biofilms grown under different conditions to describe transport phenomena in the boundary layer.

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Shu, Zhixin, Sunil Hadap, Eli Shechtman, Kalyan Sunkavalli, Sylvain Paris e Dimitris Samaras. "Portrait Lighting Transfer Using a Mass Transport Approach". ACM Transactions on Graphics 36, n. 4 (20 luglio 2017): 1. http://dx.doi.org/10.1145/3072959.3095816.

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Shu, Zhixin, Sunil Hadap, Eli Shechtman, Kalyan Sunkavalli, Sylvain Paris e Dimitris Samaras. "Portrait lighting transfer using a mass transport approach". ACM Transactions on Graphics 36, n. 4 (20 luglio 2017): 1. http://dx.doi.org/10.1145/3072959.3126847.

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Shu, Zhixin, Sunil Hadap, Eli Shechtman, Kalyan Sunkavalli, Sylvain Paris e Dimitris Samaras. "Portrait Lighting Transfer Using a Mass Transport Approach". ACM Transactions on Graphics 37, n. 1 (31 gennaio 2018): 1–15. http://dx.doi.org/10.1145/3095816.

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12

Nguyen, Xuan Linh, Ngoc Van Trinh, Younghyeon Kim e Sangseok Yu. "A Correlation of Overall Mass Transfer Coefficient of Water Transport in a Hollow-Fiber Membrane Module via an Artificial Neural Network Approach". Membranes 13, n. 1 (21 dicembre 2022): 8. http://dx.doi.org/10.3390/membranes13010008.

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Water transport in a hollow-fiber membrane depends on mass convection around the tube, mass convection inside the tube, and water diffusion through the membrane tube. The performance of water transport is then explained by the overall mass transfer coefficient in hollow-fiber membranes. This study presents the prediction of overall mass transfer coefficients of water transport in a hollow-fiber membrane module by an artificial neural network (ANN) that is used for a humidifier of a vehicular fuel cell system. The input variables of ANN are collected from water transport experiments of the hollow-fiber membrane module that is composed of inlet flow rates, inlet relative humidity, system pressures, and operating temperatures. The experimental mass transfer coefficients are the targets of the training model, which are determined via the effectiveness analysis. When unknown data are applied to the ANN model, the correlation of the overall mass transfer coefficient predicts precise results with R = 0.99 (correlation coefficient). The ANN model shows good prediction capability of water transport in membrane humidifiers.

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OLIVER, J. M., J. P. WHITELEY, M. A. SAXTON, D. VELLA, V. S. ZUBKOV e J. R. KING. "On contact-line dynamics with mass transfer". European Journal of Applied Mathematics 26, n. 5 (10 agosto 2015): 671–719. http://dx.doi.org/10.1017/s0956792515000364.

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We investigate the effect of mass transfer on the evolution of a thin, two-dimensional, partially wetting drop. While the effects of viscous dissipation, capillarity, slip and uniform mass transfer are taken into account, other effects, such as gravity, surface tension gradients, vapour transport and heat transport, are neglected in favour of mathematical tractability. Our focus is on a matched-asymptotic analysis in the small-slip limit, which reveals that the leading-order outer formulation and contact-line law depend delicately on both the sign and the size of the mass transfer flux. This leads, in particular, to novel generalisations of Tanner's law. We analyse the resulting evolution of the drop on the timescale of mass transfer and validate the leading-order predictions by comparison with preliminary numerical simulations. Finally, we outline the generalisation of the leading-order formulations to prescribed non-uniform rates of mass transfer and to three dimensions.

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Teixidó, Josep, Frederic Cofan, Mercé Borrás, Josep Bonet, Jordi Bonal, Roman Galimany, Carme Biosca e Antonio Caralps. "Mass Transfer Coefficient: Comparison between Methods". Peritoneal Dialysis International: Journal of the International Society for Peritoneal Dialysis 13, n. 2_suppl (gennaio 1993): 47–49. http://dx.doi.org/10.1177/089686089301302s12.

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The mass transfer area coefficient (MTC) is the best parameter for solute transport evaluation in continuous ambulatory peritoneal dialysis (CAPD) patients. We compared three simplified MTC methods (calculated according Garred, Krediet, or Lindholm) and the peritoneal equilibration test (PET) (Twardowskl) to complex MTC (MTCX) (Randerson and farrell) for urea and creatinine, by means of 29 tests performed In 24 stable CAPD patients. There were no significant differences (paired t-test) between MTCX and each of the simplified MTC, except for creatinine MTC calculated by Krediet's method, which was significantly different (MTCX: 9.36.:1:.4.32, K-MTC: 10.48.:1:.4.55, p<0.05). Likewise, there was an acceptable correlation between complex MTC and each of the simplified methods including the PET. However, a more detailed study of the MTC's categorizations shows poor agreement with complex MTC categorization. Better results are obtained by PET categorization, which reaches good likelihood ratios either for positive or negative events. We conclude that simplified MTC or the dialysatelplasma ratio at 240 minutes for urea and creatinine has an acceptable correlation with complex MTC and can be useful in clinical practice. There is poor agreement between solute transport categorizations of simplified MTC and complex MTC. There Is a better coincidence between the PET ( DIP at 240 minutes) and complex MTC categorizations.

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Langrish, Timothy A. G. "Multifilm Mass Transfer and Time Constants for Mass Transfer in Food Digestion: Application to Gut-on-Chip Models". Applied Biosciences 1, n. 2 (24 giugno 2022): 101–12. http://dx.doi.org/10.3390/applbiosci1020007.

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This review highlights the involvement of mass transfer in animal food-digestion processes. There may be several mass-transfer steps during the dissolution of food components, starting from the food itself, moving into the digestive juices, then moving through the walls of the gastrointestinal tract. These steps create a sequence of film resistances to mass transfer, where one film resistance often limits the overall mass-transfer process. Mass-transfer rates, mass-transfer coefficients, and the time scales and time constants for different parts of the food-digestion process are all interlinked, and the connections have been explained. In some parts of the food-digestion process, the time constants for the mass-transfer process are similar to the residence times for food digestion, emphasising the importance of mass transfer in these parts of food digestion, such as the duodenum. The mass-transfer and transport behaviour for in vivo human digestive systems and in vitro guts-on-a-chip may be very similar, suggesting that cells on the intestine walls, whether in vitro (guts-on-a-chip) or in vivo, may see similar transport behaviour for both nutrients towards the cells, and waste products away from them.

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Sherif Adham Mohamed. "Theoretical Drying Model of Water Vapor Pressure for Imbibed Porous Material with Sea Water subjected to Weather Conditions". Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 87, n. 2 (26 settembre 2021): 127–36. http://dx.doi.org/10.37934/arfmts.87.2.127136.

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The drying model of porous material has been studied and solved. The drying model solves the drying of porous material if the porous material is saturated or unsaturated with salt solution. Local thermodynamic equilibrium was not assumed in the mathematical model for describing the multi-phase flow in the unsaturated porous media using the energy and mass conservation equations to describe the heat and mass transfer during the drying. The vapor pressure inside porous material voids is built from the vapor mass transport through material thickness and from the void’s water content evaporation. The new equation in the model is water vapor pressure’s equation. The drying model included advection and capillary transport of the water in porous material pores, the gases transport by advection and diffusion and soluble salt transports by diffusion only. The environment of the boundary condition of the model is atmospheric condition in the day’s hours. The model consists of 5 equations for mass and heat transfer phenomenon. The model was solved by Matlab software. The case study of the model is concrete block.

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Noble, Richard D., J. Douglas Way e Laurel A. Powers. "Effect of external mass-transfer resistance on facilitated transport". Industrial & Engineering Chemistry Fundamentals 25, n. 3 (agosto 1986): 450–52. http://dx.doi.org/10.1021/i100023a025.

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Fadaei, Farzad, Saeed Shirazian e Seyed Nezameddin Ashrafizadeh. "Mass transfer modeling of ion transport through nanoporous media". Desalination 281 (ottobre 2011): 325–33. http://dx.doi.org/10.1016/j.desal.2011.08.025.

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Batchelor‐McAuley, Christopher, Danlei Li e Richard G. Compton. "Mass‐Transport‐Corrected Transfer Coefficients: A Fully General Approach". ChemElectroChem 7, n. 18 (15 settembre 2020): 3844–51. http://dx.doi.org/10.1002/celc.202001107.

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Jacimovski, Darko, Radmila Garic-Grulovic, Zeljko Grbavcic, Mihal Djuris e Nevenka Boskovic-Vragolovic. "Momentum, heat, and mass transfer analogy for vertical hydraulic transport of inert particles". Chemical Industry 68, n. 1 (2014): 15–25. http://dx.doi.org/10.2298/hemind130207025j.

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Wall-to-bed momentum, heat and mass transfer in vertical liquid-solids flow, as well as in single phase flow, were studied. The aim of this investigation was to establish the analogy among those phenomena. Also, effect of particles concentration on momentum, heat and mass transfer was studied. The experiments in hydraulic transport were performed in a 25.4 mm I.D. cooper tube equipped with a steam jacket, using spherical glass particles of 1.94 mm in diameter and water as a transport fluid. The segment of the transport tube used for mass transfer measurements was inside coated with benzoic acid. In the hydraulic transport two characteristic flow regimes were observed: turbulent and parallel particle flow regime. The transition between two characteristic regimes (?*=0), occurs at a critical voidage ??0.85. The vertical two-phase flow was considered as the pseudofluid, and modified mixture-wall friction coefficient (fw) and modified mixture Reynolds number (Rem) were introduced for explanation of this system. Experimental data show that the wall-to-bed momentum, heat and mass transfer coefficients, in vertical flow of pseudofluid, for the turbulent regime are significantly higher than in parallel regime. Wall-to-bed, mass and heat transfer coefficients in hydraulic transport of particles were much higher then in single-phase flow for lower Reynolds numbers (Re<15000), while for high Reynolds numbers (Re>15000), there was not significant difference. The experimental data for wall-to-bed momentum, heat and mass transfer in vertical flow of pseudofluid in parallel particle flow regime, show existing analogy among these three phenomena.

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Nagy, Endre, e Márta Vitai. "Analysis of Mass Transport through Anisotropic, Catalytic/Bio-Catalytic Membrane Reactors". Catalysts 9, n. 4 (13 aprile 2019): 358. http://dx.doi.org/10.3390/catal9040358.

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This paper investigated the steady-state mass transport process through anisotropic, composite membrane layers with variable mass transport coefficients, such as the diffusion coefficient, convective velocity, or chemical/biochemical reaction rate constant. The transfer processes can be a solution-diffusion model or diffusive plus convective process. In the theoretical part, the concentration distribution as well as the inlet and outlet mass transfer rates’ expressions are defined for physical transport processes with variable diffusion or solubility coefficients and then that for transport processes accompanied by first- and zero-order reactions, in the presence of diffusive and convective flow, with constant and variable parameters. The variation of the transport parameters as a function of the local coordinate was defined by linear equations. It was shown that the increasing diffusion coefficient or convective flow induces much lower concentrations across the membrane layer than transport processes, with their decreasing values a function of the space coordinate. Accordingly, this can strongly affect the effect of the concentration dependent chemical/biochemical reaction. The inlet mass transfer rate can also be mostly higher when the transport parameter decreases across the anisotropic membrane layer.

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Shadid, J. N., e E. R. G. Eckert. "The Mass Transfer Analogy to Heat Transfer in Fluids With Temperature-Dependent Properties". Journal of Turbomachinery 113, n. 1 (1 gennaio 1991): 27–33. http://dx.doi.org/10.1115/1.2927734.

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The analogy between heat transfer in a single-component fluid and isothermal mass transfer of a two-component fluid without chemical reaction is presented. The analogy is well established and frequently used for fluids with constant properties. However, in various applications such as in the cooling of hot components in gas turbines, the temperature varies widely, causing significant fluid property variations. The present paper reviews the constant-property situation and considers in detail the conditions necessary to ensure similarity of the two transport processes with temperature and concentration-dependent fluid properties. An application of the variable property analogy to mass transfer in binary mixtures is presented along with specific recommendations for the CO2–air and Freon-air systems. It is demonstrated that the essential similarity conditions of the analogy are very well fulfilled for film cooling, total coverage film cooling, and impingement cooling when the heat (mass) flux into the wall in the transport process is zero. The heat/mass transfer analogy can, therefore, be used with confidence for these processes.

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Nagy, Endre, e Imre Hegedüs. "Diffusive Plus Convective Mass Transport, Accompanied by Biochemical Reaction, Across Capillary Membrane". Catalysts 10, n. 10 (25 settembre 2020): 1115. http://dx.doi.org/10.3390/catal10101115.

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This study theoretically analyzes the mass transport through capillary, asymmetric, biocatalytic membrane reactor, where the diffusive plus convective mass transport is accompanied by biochemical reaction with Michaelis-Menten kinetics. An approach mathematical model was developed that provides the mass transfer properties in closed, explicit mathematical forms. The inlet and outlet mass transfer rates can then put into the differential mass transport expressions of the lumen and the shell fluid phases as boundary values. The approach solution was obtained by dividing the membrane layer into very thin sub-layers with constant transport and reaction kinetic parameters and the obtained second-order differential equation with constant parameters, given for every sublayer, could be solved analytically. Two operating modes are analyzed in this paper, namely, with and without a sweeping phase on the permeating side. These models deviate by the boundary conditions, only, defined them for the outlet membrane surface. The main purpose of this study is to show how the cylindrical space affects the transport process, concentration distribution, mass transfer rates and conversion in presence of a biochemical reaction. It is shown that the capillary transport can significantly be affected by the lumen radius, by the biocatalytic reactor thickness and the convective flow. Decreasing values of the lumen radius reduce the effect of the biochemical/chemical reaction; the increasing reactor thickness also decreases the physical mass transfer rate and, with it, increases the effect of reaction rate. The model can also be applied to reactions with more general kinetic equations with variable parameters.

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Nicholls, Melville E., e Roger A. Pielke Sr. "On the role of thermal expansion and compression in large-scale atmospheric energy and mass transports". Atmospheric Chemistry and Physics 18, n. 21 (7 novembre 2018): 15975–6003. http://dx.doi.org/10.5194/acp-18-15975-2018.

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Abstract. There are currently two views of how atmospheric total energy transport is accomplished. The traditional view considers total energy as a quantity that is transported in an advective-like manner by the wind. The other considers that thermal expansion and the resultant compression of the surrounding air causes a transport of total energy in a wave-like manner at the speed of sound. This latter view emerged as the result of detailed analysis of fully compressible mesoscale model simulations that demonstrated considerable transfer of internal and gravitational potential energy at the speed of sound by Lamb waves. In this study, results are presented of idealized experiments with a fully compressible model designed to examine the large-scale transfers of total energy and mass when local heat sources are prescribed. For simplicity a Cartesian grid was used, there was a horizontally homogeneous and motionless initial state, and the simulations did not include moisture. Three main experimental designs were employed. The first has a convective-storm-scale heat source and does not include the Coriolis force. The second experiment has a continent-scale heat source prescribed near the surface to represent surface heating and includes a constant Coriolis parameter. The third experiment has a cloud-cluster-scale heat source prescribed at the equator and includes a latitude-dependent Coriolis parameter. Results show considerable amounts of meridional total energy and mass transfer at the speed of sound. This suggests that the current theory of large-scale total energy transport is incomplete. It is noteworthy that comparison of simulations with and without thermally generated compression waves show that for a very large-scale heat source there are fairly small but nevertheless significant differences of the wind field. These results raise important questions related to the mass constraints when calculating meridional energy transports, the use of semi-implicit time differencing in large-scale global models, and the use of the term “heat transfer” for total energy transfer.

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Sarsembayeva, Assel, Askar Zhussupbekov e Philip E. F. Collins. "Heat and Mass Transfer by Vapour in Freezing Soils". Energies 15, n. 4 (18 febbraio 2022): 1515. http://dx.doi.org/10.3390/en15041515.

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Vapour mass transfer is often underestimated when designing the bases for structures in frost susceptible soils. Intensive and long-term vapour transport may lead to excessive frost heaving and associated issues. A vapour transport model and the algorithm of its calculation is presented in this study based on the results of experimental freeze–thaw cycles of nine soil samples with varied density. The temperature field distribution, air voids volume and the energy comprising latent heat for the phase transition and heat extracted during the temperature drop are the main parameters for determining the vapour velocity and the amount of ice formed. According to the results, the average speed of vapour transport in frozen soils was about 0.4 m/h. The amount of ice built in 1 h during uniaxial freezing due to the saturated vapour pressure difference was 1.64 × 10−5–3.6 × 10−⁵ g/h in loose samples and 1.41 × 10−⁶ g/h to 5.61 × 10−⁷ g/h in dense samples of 10 cm diameter and 10 cm high sections. The results show that vapour mass transfer can increase the risk of ice growth and related problems.

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Iwanowska-Chomiak, B., e A. Walicka. "Mass Transport Through Interstitial Structures". International Journal of Applied Mechanics and Engineering 24, n. 4 (1 novembre 2019): 66–91. http://dx.doi.org/10.2478/ijame-2019-0050.

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Abstract Interstitial space, also called interstitum, separating the vital organs of a human body, is the primary source of lymph and is a major fluid compartment in the body. Interstitial space (IS) is filled out by thick collagen (CL) bundles which form lattices represented by a network of capillaries. This network has the structure similar to a sponge porous matrix (SPM) with pores-capillaries of variable cross-section. To analyse the mass transport of interstitial fluids (IFs) through the porous matrix it is assumed that the SPM is composed of an irregular system of pores which may be modelled as a fractal porous matrix. The interstitial fluids can be either bio-suspensions or bio-solutions and therefore they have to be modelled as non-Newtonian fluids. Analysing the fluid flow through the porous matrix it is assumed that the SPM is modelled as capillary tubes of variable radii. Introducing a hindrance factor allowed us to consider the porous matrix as a system of fractal capillaries but of constant radii. Classical and fractal expressions for the flow rate, velocity and permeability are derived based on the physical properties of the capillary model of interstitial structures. Each parameter in the proposed expressions does not contain any empirical constant and has a clear physical meaning, and the proposed fractals models relate the flow properties of the fluids under consideration with the structural parameters of interstitium as a porous medium.

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Stankovic, Snezana. "Transport properties and permeability of textile materials". Chemical Industry 77, n. 3 (2023): 177–79. http://dx.doi.org/10.2298/hemind230921022s.

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Heat and mass transfer through textile fabrics play a crucial role in achieving optimal thermal comfort perception by a person. The governing properties of textile fabrics by which they influence heat and mass transfer from the human skin to the environment are thermal transport capacity, water vapor permeability, and air permeability. The transfer of liquid moisture through textiles is important for thermal comfort during frequent changes in physical activity or climate. Despite numerous studies on the transport properties of textile materials over the past years, investigation in this subject area is still needed. This special issue includes five articles that offer valuable information on the subject. Both commercial and specially designed textile structures were investigated within the presented studies with the ambitious goal of providing a new understanding of their transport properties. Within the first four papers presented, certain aspects of heat and mass transfer through textile materials were analyzed at the three scale levels: microscopic (fiber type), mesoscopic (yarn geometry and fineness), and macroscopic (fabric porosity) levels. The fifth article dealt with the influence of the seam type and the sewing thread fineness on the transport properties of the seamed structure.

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Maier, Lukas, Lars Kufferath-Sieberin, Leon Pauly, Manuel Hopp-Hirschler, Götz T. Gresser e Ulrich Nieken. "Constitutive Correlations for Mass Transport in Fibrous Media Based on Asymptotic Homogenization". Materials 16, n. 5 (28 febbraio 2023): 2014. http://dx.doi.org/10.3390/ma16052014.

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Mass transport in textiles is crucial. Knowledge of effective mass transport properties of textiles can be used to improve processes and applications where textiles are used. Mass transfer in knitted and woven fabrics strongly depends on the yarn used. In particular, the permeability and effective diffusion coefficient of yarns are of interest. Correlations are often used to estimate the mass transfer properties of yarns. These correlations commonly assume an ordered distribution, but here we demonstrate that an ordered distribution leads to an overestimation of mass transfer properties. We therefore address the impact of random ordering on the effective diffusivity and permeability of yarns and show that it is important to account for the random arrangement of fibers in order to predict mass transfer. To do this, Representative Volume Elements are randomly generated to represent the structure of yarns made from continuous filaments of synthetic materials. Furthermore, parallel, randomly arranged fibers with a circular cross-section are assumed. By solving the so-called cell problems on the Representative Volume Elements, transport coefficients can be calculated for given porosities. These transport coefficients, which are based on a digital reconstruction of the yarn and asymptotic homogenization, are then used to derive an improved correlation for the effective diffusivity and permeability as a function of porosity and fiber diameter. At porosities below 0.7, the predicted transport is significantly lower under the assumption of random ordering. The approach is not limited to circular fibers and may be extended to arbitrary fiber geometries.

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Omar, Roshartini, Tan Khai Hua, Aina Mardia Sallehuddin, Norliana Sarpin, Mohd Yamani Yahya, Goh Kai Chen, Sulzakimin Mohamed e Md Asrul Nasid Masrom. "Implementation of Technology Transfer in Mass Rapid Transport (MRT) Project in Malaysia". MATEC Web of Conferences 266 (2019): 03022. http://dx.doi.org/10.1051/matecconf/201926603022.

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Technology transfer is a useful resource for improving technology and it is widely used in various industrial fields. The application of technology transfer in the construction industry can be viewed via the Mass Rapid Transit (MRT). The transfer of technology has been implemented in the construction of the MRT but there are a number of factors and barriers in implementing as well. Therefore, this study attempts to understand the technology transfer in the MRT project in the country and study the factors that influence the process of technology transfer in the MRT project. Data collection was conducted through interviews with respondents involved in technology transfer MRT project namely MRT Corporation Sdn. Bhd. And MMC-Gamuda KVMRT (PDP) Sdn. Bhd. The results showed organisational capabilities, relational capabilities, communications, level of absorptive capacity and technological capabilities, development of skilled human resources and economic advancement are factors that influenced the transfer of technology in MRT project. The findings of this study can be used as a guide for the MRT project in the future to avoid failure in the technology transfer.

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Ivanyshyn, Volodymyr, Lesia Sheludchenko, Taras Hutsol, Anatolii Rud e Dmytro Skorobogatov. "MASS TRANSFER MANAGEMENT AND DEPOSITION OF CONTAMINANTS WITHIN CAR ROAD ZONES". ENVIRONMENT. TECHNOLOGIES. RESOURCES. Proceedings of the International Scientific and Practical Conference 1 (20 giugno 2019): 70. http://dx.doi.org/10.17770/etr2019vol1.4145.

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The present study determined that the essential factor of technogenic influence on the roadside landscapes is a motor complex that leads to the alienation of large territories, destabilizing of the natural ecosystems, the disarticulation of landscapes and an irreversible transformation of nature and territorial complexes in general. The significant influence of motor transport is the exhaust emissions with Carbon (ІІ) oxide, Nitrogen oxides, hydrocarbons, aldehydes, soot (technical carbon), mineral dust, heavy metals, etc., that influence not only on the environment, but also on the health of the population. The migration and deposition of the pollutants that are produced by vehicle flows are caused by many factors of different genesis. In particular, this landscape topographic characteristics and the geochemical territory activity of natural and technogenic geo-ecosystems, structure of biocoenoses, presence of geochemical barriers (including artificially created), density, construction, transport, physical and geographical, social and economic features of transport network infrastructure, the intensity of transport flows, etc. Therefore, to ensure the environmentally safe operation of "car – road – environment" system should include a systematic approach to the development concept of the transport complex within the specific natural and man-made geo-ecosystems with developed automobile and communication networks that would provide not only its economic and transport feasibility, but also minimizing the anthropogenic transformation of natural and territorial complexes in general. To reduce eco-destructive impact we recommend to apply the developed design of forest of gas and dustproof lane road that substantially reduce the dangerous zone of influence.

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31

Kissel, John C. "Modeling Mass Transfer in Biological Wastewater Treatment Processes". Water Science and Technology 18, n. 6 (1 giugno 1986): 35–45. http://dx.doi.org/10.2166/wst.1986.0059.

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Parameters characterizing intrasolid, liquid/solid, and gas/liquid mass transport phenomena in biological treatment systems are required if mass transfer is to be included in process models. Estimates of such parameters are presented and discussed. Collective and individual effects of mass transfer resistances are illustrated by computer simulation of a high-rate trickling filter.

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32

GARCÍA-YBARRA, PEDRO L., e JOSE L. CASTILLO. "Mass transfer dominated by thermal diffusion in laminar boundary layers". Journal of Fluid Mechanics 336 (10 aprile 1997): 379–409. http://dx.doi.org/10.1017/s0022112096004661.

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The concentration distribution of massive dilute species (e.g. aerosols, heavy vapours, etc.) carried in a gas stream in non-isothermal boundary layers is studied in the large-Schmidt-number limit, Sc[Gt ]1, including the cross-mass-transport by thermal diffusion (Ludwig–Soret effect). In self-similar laminar boundary layers, the mass fraction distribution of the dilute species is governed by a second-order ordinary differential equation whose solution becomes a singular perturbation problem when Sc[Gt ]1. Depending on the sign of the temperature gradient, the solutions exhibit different qualitative behaviour. First, when the thermal diffusion transport is directed toward the wall, the boundary layer can be divided into two separated regions: an outer region characterized by the cooperation of advection and thermal diffusion and an inner region in the vicinity of the wall, where Brownian diffusion accommodates the mass fraction to the value required by the boundary condition at the wall. Secondly, when the thermal diffusion transport is directed away from the wall, thus competing with the advective transport, both effects balance each other at some intermediate value of the similarity variable and a thin intermediate diffusive layer separating two outer regions should be considered around this location. The character of the outer solutions changes sharply across this thin layer, which corresponds to a second-order regular turning point of the differential mass transport equation. In the outer zone from the inner layer down to the wall, exponentially small terms must be considered to account for the diffusive leakage of the massive species. In the inner zone, the equation is solved in terms of the Whittaker function and the whole mass fraction distribution is determined by matching with the outer solutions. The distinguished limit of Brownian diffusion with a weak thermal diffusion is also analysed and shown to match the two cases mentioned above.

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33

Roy, Ashis Kumar, Apu Kumar Saha e Sudip Debnath. "Unsteady Convective Diffusion with Interphase Mass Transfer in Casson Liquid". Periodica Polytechnica Chemical Engineering 62, n. 2 (9 agosto 2017): 215. http://dx.doi.org/10.3311/ppch.10328.

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This study aims to examine the dispersion of a passive contaminant of solute released in Casson liquid flow through a tube. The wall of the tube is taken to be chemically active where the flow is driven by the constant pressure gradient. To evaluate the transport coefficients, Aris-Barton’s Moment technique is considered, a finite difference implicit scheme is adopted to handle the differential equation arises in moment methodology. Also to confirm the results obtained by Aris-Barton’s method, the generalized dispersion model has been applied. Unlike the previous studies on dispersion in Casson liquid, the time-dependent behavior of the transport coefficients has been established. Some significant observations have been founded, e.g. exchange coefficient is independent of yield stress while the convection coefficient and dispersion coefficient are inversely proportional to yield stress. Results reveal that transport coefficients are enormously affected by wall absorption.

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Silva, O., J. Carrera, M. Dentz, S. Kumar, A. Alcolea e M. Willmann. "A general real-time formulation for multi-rate mass transfer problems". Hydrology and Earth System Sciences 13, n. 8 (5 agosto 2009): 1399–411. http://dx.doi.org/10.5194/hess-13-1399-2009.

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Abstract. Many flow and transport phenomena, ranging from delayed storage in pumping tests to tailing in river or aquifer tracer breakthrough curves or slow kinetics in reactive transport, display non-equilibrium (NE) behavior. These phenomena are usually modeled by non-local in time formulations, such as multi-porosity, multiple processes non equilibrium, continuous time random walk, memory functions, integro-differential equations, fractional derivatives or multi-rate mass transfer (MRMT), among others. We present a MRMT formulation that can be used to represent all these models of non equilibrium. The formulation can be extended to non-linear phenomena. Here, we develop an algorithm for linear mass transfer, which is accurate, computationally inexpensive and easy to implement in existing groundwater or river flow and transport codes. We illustrate this approach by application to published data involving NE groundwater flow and solute transport in rivers and aquifers.

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35

Berman, J., e L. F. Mockros. "Mass Transfer to Fluids Flowing Through Rotating Nonaligned Straight Tubes". Journal of Biomechanical Engineering 108, n. 4 (1 novembre 1986): 342–49. http://dx.doi.org/10.1115/1.3138626.

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Relatively inefficient heat/mass transfer is characteristic of tubular devices if the Reynolds number is low. One method of improving the heat/mass transfer efficiency of such devices is by inducing transverse laminar secondary circulations that are superimposed on the primary flow field; the resulting transverse velocity components lead to fluid mixing and hence augmented mass transfer in the tube lumen. The present work is a theoretical and experimental investigation of the enhanced transport in rotating, nonaligned, straight tubes, a method of transport enhancement that utilizes Coriolis acceleration to create transverse fluid mixing. This technique couples the transport advantages of coiled tubes with the design advantages of straight tubes. The overall mass balance equation is numerically solved for transfer into fluids flowing steadily through rotating nonaligned straight tubes. This solution, for small Coriolis disturbances, incorporates a third order perturbation solution for the primary and secondary flow fields. For sufficiently small Coriolis disturbances the bulk concentration increase is found to be uniquely determined by the value of a single similarity parameter. As the Coriolis disturbance is increased, however, two additional parameters are required to accurately characterize the mass transfer. In general, increasing the Coriolis accelerations results in an increase in mass transfer. There are solution regimes, however, in which increasing this acceleration can lead to a decrease in mass transfer efficiency. This interesting phenomena, which has important design implications, appears to result from velocity-weighting effects on the exiting sample. Experiments, involving the measurement of oxygen transferred into water and blood, produced data that agree with the theoretical predictions.

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36

Hayat, T., Fahad Abbasi e A. Alsaedi. "Peristaltic Transport with Convective Conditions of Heat and Mass Transfer". Journal of Applied Fluid Mechanics 9, n. 3 (1 maggio 2016): 1525–32. http://dx.doi.org/10.18869/acadpub.jafm.68.228.22729.

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37

Kuhn, R. C., F. Maugeri Filho, V. Silva, L. Palacio, A. Hernández e P. Prádanos. "Mass transfer and transport during purification of fructooligosaccharides by nanofiltration". Journal of Membrane Science 365, n. 1-2 (dicembre 2010): 356–65. http://dx.doi.org/10.1016/j.memsci.2010.09.031.

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38

Bhattacharya, A. "Kinetic modelling of mass transport limited phase transfer catalysed reactions". Journal of Molecular Catalysis A: Chemical 181, n. 1-2 (25 marzo 2002): 243–56. http://dx.doi.org/10.1016/s1381-1169(01)00369-7.

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Afonso, Maria Diná, e Maria Norberta de Pinho. "Mass Transfer Modeling for Salt Transport in Amphoteric Nanofiltration Membranes". Industrial & Engineering Chemistry Research 37, n. 10 (ottobre 1998): 4118–27. http://dx.doi.org/10.1021/ie980092p.

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40

OHSHIMA, Norio, e Masaaki SATO. "Transport Phenomena in the Biological System : Part 2, Mass Transfer". Journal of the Society of Mechanical Engineers 89, n. 807 (1986): 129–37. http://dx.doi.org/10.1299/jsmemag.89.807_129.

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41

CVETKOVIC, V., J. O. SELROOS e H. CHENG. "Transport of reactive tracers in rock fractures". Journal of Fluid Mechanics 378 (10 gennaio 1999): 335–56. http://dx.doi.org/10.1017/s0022112098003450.

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Transport of tracers subject to mass transfer reactions in single rock fractures is investigated. A Lagrangian probabilistic model is developed where the mass transfer reactions are diffusion into the rock matrix and subsequent sorption in the matrix, and sorption on the fracture surface as well as on gauge (infill) material in the fracture. Sorption reactions are assumed to be linear, and in the general case kinetically controlled. The two main simplifying assumptions are that diffusion in the rock matrix is one-dimensional, perpendicular to the fracture plane, and the tracer is displaced within the fracture plane by advection only. The key feature of the proposed model is that advective transport and diffusive mass transfer are related in a dynamic manner through the flow equation. We have identified two Lagrangian random variables τ and β as key parameters which control advection and diffusive mass transfer, and are determined by the flow field. The probabilistic solution of the transport problem is based on the statistics of (τ, β), which we evaluated analytically using first-order expansions, and numerically using Monte Carlo simulations. To study (τ, β)-statistics, we assumed the ‘cubic law’ to be applicable locally, whereby the pressure field is described with the Reynolds lubrication equation. We found a strong correlation between τ and β which suggests a deterministic relationship β∼τ3/2; the exponent 3/2 is an artifact of the ‘cubic law’. It is shown that flow dynamics in fractures has a strong influence on the variability of τ and β, but a comparatively small impact on the relationship between τ and β. The probability distribution for the (decaying) tracer mass recovery is dispersed in the parameter space due to fracture aperture variability.

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42

Beris, Antony N., Soham Jariwala e Norman J. Wagner. "Flux-based modeling of heat and mass transfer in multicomponent systems". Physics of Fluids 34, n. 3 (marzo 2022): 033113. http://dx.doi.org/10.1063/5.0085444.

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In the present work, the macroscopic governing equations governing the heat and mass transfer for a general multicomponent system are derived via a systematic nonequilibrium thermodynamics framework. In contrast to previous approaches, the relative (with respect to the mass average velocity) component mass fluxes (relative species momenta) and the heat flux are treated explicitly, in complete analogy with the momentum flux. The framework followed here, in addition to allowing for the description of relaxation phenomena in heat and mass transfer, establishes to the fullest the analogy between all transport processes, momentum, heat, and mass transfer, toward which R. B. Bird contributed so much with his work. The inclusion of heat flux-based momentum as an additional variable allows for the description of relaxation phenomena in heat transfer as well as of mixed (Soret and Dufour) effects, coupling heat and mass transfer. The resulting models are Galilean invariant, thereby resolving a conundrum in the field, and always respect the second law of thermodynamics, for appropriate selection of transport parameters. The general flux-based dynamic equations reduce to the traditional transport equations in the limit when mass species and heat relaxation effects are negligible and are fully consistent with the equations established from the application of kinetic theory in the limit of dilute gases. As an added benefit, for the particular example case of hyperbolic diffusion we illustrate the application of the proposed models as a method to allow the use of powerful numerical solvers normally not available for solving mass transfer models more generally.

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Avendaño-Garrido, Martha L., José R. Gabriel-Argüelles, Ligia Quintana-Torres e Efrén Mezura-Montes. "A metaheuristic for a numerical approximation to the mass transfer problem". International Journal of Applied Mathematics and Computer Science 26, n. 4 (1 dicembre 2016): 757–66. http://dx.doi.org/10.1515/amcs-2016-0053.

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Abstract This work presents an improvement of the approximation scheme for the Monge-Kantorovich (MK) mass transfer problem on compact spaces, which is studied by Gabriel et al. (2010), whose scheme discretizes the MK problem, reduced to solve a sequence of finite transport problems. The improvement presented in this work uses a metaheuristic algorithm inspired by scatter search in order to reduce the dimensionality of each transport problem. The new scheme solves a sequence of linear programming problems similar to the transport ones but with a lower dimension. The proposed metaheuristic is supported by a convergence theorem. Finally, examples with an exact solution are used to illustrate the performance of our proposal.

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Mazumder, Ankita, Dwaipayan Sen e Chiranjib Bhattacharjee. "Mass Transport through Composite Asymmetric Membranes". Diffusion Foundations 23 (agosto 2019): 151–72. http://dx.doi.org/10.4028/www.scientific.net/df.23.151.

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In recent years, membrane separation technology has emerged as efficient and promising separation process from laboratory scale applications to wide range of technical industrial applications. The development of composite asymmetric membrane is a major breakthrough in membrane research field, as this membrane offers significantly high selectivity without affecting the mechanical durability of the membranes. In this chapter, structural characteristics and different fabrication techniques of composite membranes are reviewed. Moreover the mass transfer mechanism through the composite asymmetric membrane is described in details following solution-diffusion theory, Knudsen diffusion, and series resistance model. Composite membranes are preferred over others because of the high flux and enhanced selectivity without disturbing the mechanical stability of the membranes. These membranes are now widely employed in the applications of reverse osmosis (RO), nanofiltration (NF), pervaporation, gas separation, hydrocarbon fractionations, etc. As composite asymmetric membranes are “tailor-made” in nature, membrane characteristics can be tuned accordingly depending on their end use. Therefore plentiful research opportunities still exist to elevate their performance ability in terms of stability, selectivity and fouling resistance, which will in turn augment its application domain.

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Harmon, T. C., e P. V. Roberts. "Determining and Modeling Mass-Transfer Rate Limitations in Heterogeneous Aquifers". Water Science and Technology 26, n. 1-2 (1 luglio 1992): 71–77. http://dx.doi.org/10.2166/wst.1992.0387.

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This work focuses on assessing mass-transfer rate limitations on the transport of aqueous phase volatile organic chemicals (VOCs) in real aquifer systems. The rate limiting mechanism is considered as diffusion through immobile regions of a porous medium, i.e., through intra-particle, intra-aggregate, intra-layer pores, or through a series of such zones. Sorption/desorption studies are reviewed for two experimental aquifers: the large-scale, relatively homogeneous Borden site, and the pilot-scale, relatively heterogeneous Moffett site. The flame-sealed ampule method, with accompanying intermittent purge, is discussed with respect to supplying diffusion rate parameters for homogeneous and heterogeneous solute transport models.

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46

Yoo, Seong-Yeon, Jong-Hark Park, Chang-Hwan Chung e Moon-Ki Chung. "An Experimental Study on Heat/Mass Transfer From a Rectangular Cylinder". Journal of Heat Transfer 125, n. 6 (19 novembre 2003): 1163–69. http://dx.doi.org/10.1115/1.1603780.

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Local and average mass transfer rates from a rectangular cylinder having various width to height ratios are measured using naphthalene sublimation technique, and influence of flow characteristics on mass transfer is investigated. The experimental apparatus comprises a wind tunnel, a naphthalene casting facility and a sublimation depth measurement system. Mass transfer data are compared with those of heat transfer which are obtained using thermocouples in the constant heat flux boundary condition, and analogy between heat and mass transfer is examined. The reasons for discrepancy in both transport values are explained in detail.

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Yue, Lindsey, Leanne Reich, Terrence Simon, Roman Bader e Wojciech Lipiński. "Progress in thermal transport modeling of carbonate-based reacting systems". International Journal of Numerical Methods for Heat & Fluid Flow 27, n. 5 (2 maggio 2017): 1098–107. http://dx.doi.org/10.1108/hff-03-2016-0087.

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Purpose Carbonate-based heterogeneous reacting systems are investigated for the applications of thermochemical carbon dioxide capture and energy storage. This paper aims to review recent progress in numerical modeling of thermal transport phenomena in such systems. Design/methodology/approach Calcium oxide looping is selected as the model carbonate-based reacting system. Numerical models coupling heat and mass transfer to chemical kinetics are reviewed for solar-driven calcium oxide looping on the sorbent particle, particle bed, and reactor levels. Findings At the sorbent particle level, a transient numerical model of heat and mass transfer coupled to chemical kinetics has been developed for a single particle undergoing cyclic calcination and carbonation driven by time-periodic boundary conditions. Modeling results show cycle times impact the maximum sorbent utilization and solar-to-chemical energy efficiency. At the reactor level, a model of heat and mass transfer coupled to chemical kinetics of calcination of a packed-bed reactor concept has been developed to estimate the reactor’s performance. The model was used to finalize reactor geometry by evaluating pressure drops, temperature distributions, and heat transfer in the reactor. Originality/value Successful solar thermochemical reactor designs maximize solar-to-chemical energy conversion by matching chemical kinetics to reactor heat and mass transfer processes. Modeling furthers the understanding of thermal transport phenomena and chemical kinetics interactions and guides the design of solar chemical reactors.

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Vakouftsi, E., G. Marnellos, C. Athanasiou e Frank A. Coutelieris. "Modeling of Flow and Transport Processes Occurred in a Typical Polymer Electrolyte Membrane Fuel Cell (PEMFC)". Defect and Diffusion Forum 273-276 (febbraio 2008): 87–92. http://dx.doi.org/10.4028/www.scientific.net/ddf.273-276.87.

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In the present work, a three dimensional model examining the fluid flow along with the fundamental transport phenomena occurring in a typical polymer electrolyte fuel cell (PEMFC), i.e. heat transfer, mass transport and charge transfer, has been developed. The flow field was simulated according to the well known Navier-Stokes equations, while the heat transfer was described by the typical conduction/convection equation and the mass transport by the convection/diffusion one. Furthermore, reaction kinetics were studied by the Butler-Volmer equation for the heterogeneous reactions occurring at the porous electrodes. The developed model was numerically solved by using the commercially available CFD package CFD-RC©, which is based on the multi-step finite volume method. The fuel cell performance in terms of velocity, temperature, mass fractions of active compounds and electric field has been investigated as well.

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Templis, Chrysovalantis C., e Nikos G. Papayannakos. "Mass and Heat Transfer Coefficients in Automotive Exhaust Catalytic Converter Channels". Catalysts 9, n. 6 (4 giugno 2019): 507. http://dx.doi.org/10.3390/catal9060507.

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Mass and heat transfer coefficients (MTC and HTC) in automotive exhaust catalytic monolith channels are estimated and correlated for a wide range of gas velocities and prevailing conditions of small up to real size converters. The coefficient estimation is based on a two dimensional computational fluid dynamic (2-D CFD) model developed in Comsol Multiphysics, taking into account catalytic rates of a real catalytic converter. The effect of channel size and reaction rates on mass and heat transfer coefficients and the applicability of the proposed correlations at different conditions are discussed. The correlations proposed predict very satisfactorily the mass and heat transfer coefficients calculated from the 2-D CFD model along the channel length. The use of a one dimensional (1-D) simplified model that couples a plug flow reactor (PFR) with mass transport and heat transport effects using the mass and heat transfer correlations of this study is proved to be appropriate for the simulation of the monolith channel operation.

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Yaqub, Asim, Huma Ajab, Saqib Khan, Sajjad Khan e Robina Farooq. "Electrochemical Removal of Copper and Lead from Industrial Wastewater: Mass Transport Enhancement". Water Quality Research Journal 44, n. 2 (1 maggio 2009): 183–88. http://dx.doi.org/10.2166/wqrj.2009.020.

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Abstract The effects of ultrasonic frequencies on both the mass transport process and diffusion layer were investigated during electrochemical treatment. The rates of mass transfer at a stainless steel cathode were measured for copper and lead in dilute acidified copper sulphate and lead nitrate solutions at different ultrasonic frequencies. Concentrations in bulk solution were determined by atomic absorption spectrophotometer. By increasing frequencies from 40 to 100 kHz, a high value for the mass transfer coefficient and an effective thinning of the diffusion layer were observed. Higher rates of mass transfer reduced energy consumption. Use of ultrasound with electrochemical processes can provide valuable contributions to remove metallic ions from industrial wastewater without using extra chemicals. The process has efficiently reduced the cost of energy consumption and deposition time.

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