Transfer closed and transfer open multimaps in minimal spaces
International Nuclear Information System (INIS)
Alimohammady, M.; Roohi, M.; Delavar, M.R.
2009-01-01
This paper is devoted to introduce the concepts of transfer closed and transfer open multimaps in minimal spaces. Also, some characterizations of them are considered. Further, the notion of minimal local intersection property will be introduced and characterized. Moreover, some maximal element theorems via minimal transfer closed multimaps and minimal local intersection property are given.
Mass transfer effects in feeder flow-accelerated corrosion wall thinning
International Nuclear Information System (INIS)
Pietralik, J.
2008-01-01
Flow conditions play a dominant role in Flow-Accelerated Corrosion (FAC) under certain conditions, e.g., in CANDU feeders. While chemistry and materials set the overall potential for FAC, flow conditions determine the local distribution of wall thinning. Recent plant data of feeders and laboratory tests confirms that there is a close relationship between local flow conditions, expressed by mass transfer coefficient, and FAC rate in CANDU feeder bends. The knowledge of local effects can be useful for minimizing the number of inspected components, predicting the location of the highest FAC rate for a given piping component, and determining what components or feeders should be replaced. A similar evaluation applies also to FAC in heat transfer equipment such as heat exchangers and steam generators. The objective of this paper is to examine the relationship between FAC rate and local mass transfer parameters. For FAC where the flow is dominant, the FAC rate is proportional to mass flux of ferrous ions. The mass flux is the product of the mass transfer coefficient and the concentration difference, or degree of saturation. The mass transfer coefficient describes the intensity of the transport of corrosion products (ferrous ions) from the oxide-water interface into the bulk water. Therefore, this parameter can be used for predicting the local distribution of FAC rate in the mass-transfer controlled FAC. The degree of saturation reduces the mass flux, thus reducing the FAC rate. This effect can be significant in long piping, e.g., in outlet feeders. The paper presents plant and laboratory evidence for the relationship between local mass transfer conditions and the FAC rate. It shows correlations for mass transfer coefficient in components that are highly susceptible to FAC and most important flow parameters that affect mass transfer coefficient. The role of surface roughness, wall shear stress, and local turbulence is also discussed. (author)
Mass transfer in nano-fluids: A review
International Nuclear Information System (INIS)
Ashrafmansouri, Seyedeh-Saba; Esfahany, Mohsen Nasr
2014-01-01
Growing attention has been recently paid to nano-fluids because of their potential for augmenting transfer processes - i.e., heat and mass transfer. Conflicting results have been reported in the literature on mass transfer in nano-fluids. The aim of this paper is to summarize the literature on mass transfer in nano-fluids stating the conflicts and possible reasons. Literature on mass transfer in nano-fluids has been reviewed in two sections. The first section concentrates on surveying mass diffusivity in nano-fluids while the second section focuses on convective mass transfer in nano-fluids. In each section, published articles, type of nano-fluids used, size and concentration range of nanoparticles, measurement methods, maximum observed enhancement, and suggested mass transport mechanisms are summarized. (authors)
Handbook of heat and mass transfer. Volume 2
International Nuclear Information System (INIS)
Cheremisinoff, N.P.
1986-01-01
This two-volume series, the work of more than 100 contributors, presents advanced topics in industrial heat and mass transfer operations and reactor design technology. Volume 2 emphasizes mass transfer and reactor design. Some of the contents discussed are: MASS TRANSFER PRINCIPLES - Effect of turbulence promoters on mass transfer. Mass transfer principles with homogeneous and heterogeneous reactions. Convective diffusion with reactions in a tube. Transient mass transfer onto small particles and drops. Modeling heat and mass transport in falling liquid films. Heat and mass transfer in film absorption. Multicomponent mass transfer: theory and applications. Diffusion limitation for reaction in porous catalysts. Kinetics and mechanisms of catalytic deactivation. DISTILLATION AND EXTRACTION - Generalized equations of state for process design. Mixture boiling. Estimating vapor pressure from normal boiling points of hydrocarbons. Estimating liquid and vapor molar fractions in distillation columns. Principles of multicomponent distillation. Generalized design methods for multicomponent distillation. Interfacial films in inorganic substances extraction. Liquid-liquid extraction in suspended slugs. MULTIPHASE REACTOR SYSTEMS - Reaction and mass transport in two-phase reactors. Mass transfer and kinetics in three-phase reactors. Estimating liquid film mass transfer coefficients in randomly packed columns. Designing packed tower wet scrubbers - emphasis on nitrogen oxides. Gas absorption in aerated mixers. Axial dispersion and heat transfer in gas-liquid bubble columns. Operation and design of trickle-bed reactors
Vrentas, James S
2013-01-01
The book first covers the five elements necessary to formulate and solve mass transfer problems, that is, conservation laws and field equations, boundary conditions, constitutive equations, parameters in constitutive equations, and mathematical methods that can be used to solve the partial differential equations commonly encountered in mass transfer problems. Jump balances, Green’s function solution methods, and the free-volume theory for the prediction of self-diffusion coefficients for polymer–solvent systems are among the topics covered. The authors then use those elements to analyze a wide variety of mass transfer problems, including bubble dissolution, polymer sorption and desorption, dispersion, impurity migration in plastic containers, and utilization of polymers in drug delivery. The text offers detailed solutions, along with some theoretical aspects, for numerous processes including viscoelastic diffusion, moving boundary problems, diffusion and reaction, membrane transport, wave behavior, sedime...
Heat and Mass Transfer Remote Control in Bioreactors of Technological Lines
Directory of Open Access Journals (Sweden)
Viktorija M. Mel’nick
2017-10-01
Full Text Available Background. The main problems that arise when using equipment for cultivation are to ensure the heat and mass transfer processes in devices, presence of turbulent and stagnant zones, high-energy consumption, low heat transfer coefficients when working with viscous fluids. Objective. The aim of the paper is the experimental determination of the remote control heat transfer advantages in production line bioreactors using ultrasonic beam compared to contact methods. Methods. An experimental study of the heat and mass transfer process in a bioreactor on the stand with UZP-6-1 immersion unit of the ultrasonic radiator with radiation frequency 42 kHz is carried out. Results. Sound waves emitted into a liquid form a concentration zone of passable sound energy in the confocal vessel form of a cylindrical surface and force the liquid to move along the inner surface of the glass along the ascending cylindrical spiral, forming a motive flow throughout the volume, causing peripheral layers of liquid and bottom layers to move in a horizontal and vertical planes, without leaving stagnant zones. The closer to the coincidence angle is the directed ultrasonic beam the greater is the effectiveness of the driving flow. Conclusions. The use of sound waves allows obtaining a high-quality product in technological lines based on bioreactors with minimal risk for the technological process. Radiation parameters and working volume physic-mechanical properties change allow fully using the properties of resonant manifestations of the sound wave influence on the working liquid with minimal costs.
Mass transfer in counter current flows
Energy Technology Data Exchange (ETDEWEB)
Doichinova, Maria D.; Popova, Petya G.; Boyadjiev, Christo B. [Bulgarian Academy of Science, Institute of Chemical Engineering, Sofia (Bulgaria)
2011-07-01
A theoretical analysis of gas-liquid counter-current flow in laminar boundary layers with flat phase boundary based on similarity variables method has been done. The obtained numerical results for the energy dissipation, mass transfer rate and their ratio are compared with analogous results for concurrent flows. A diffusion type of model is proposed for modeling of the mass transfer with chemical reaction in the column apparatuses in the cases of circulation zones. The presence of rising and descending flows (the change of the velocity direction) leads to using three coordinate systems. An iterative algorithm for the concentration distribution calculation is proposed. The influence of the zones breadths on the mass transfer efficiency in the column is investigated. Key words: efficiency, mass transfer, velocity distribution, column apparatuses, circulation zones.
Gas mass transfer for stratified flows
International Nuclear Information System (INIS)
Duffey, R.B.; Hughes, E.D.
1995-01-01
We analyzed gas absorption and release in water bodies using existing surface renewal theory. We show a new relation between turbulent momentum and mass transfer from gas to water, including the effects of waves and wave roughness, by evaluating the equilibrium integral turbulent dissipation due to energy transfer to the water from the wind. Using Kolmogoroff turbulence arguments the gas transfer velocity, or mass transfer coefficient, is then naturally and straightforwardly obtained as a non-linear function of the wind speed drag coefficient and the square root of the molecular diffusion coefficient. In dimensionless form, the theory predicts the turbulent Sherwood number to be Sh t = (2/√π)Sc 1/2 , where Sh t is based on an integral dissipation length scale in the air. The theory confirms the observed nonlinear variation of the mass transfer coefficient as a function of the wind speed; gives the correct transition with turbulence-centered models for smooth surfaces at low speeds; and predicts experimental data from both laboratory and environmental measurements within the data scatter. The differences between the available laboratory and field data measurements are due to the large differences in the drag coefficient between wind tunnels and oceans. The results also imply that the effect of direct aeration due to bubble entrainment at wave breaking is no more than a 20% increase in the mass transfer for the highest speeds. The theory has importance to mass transfer in both the geo-physical and chemical engineering literature
Directory of Open Access Journals (Sweden)
Mamatha S. Upadhay
2017-01-01
Full Text Available Heat and mass flux conditions on magnetohydrodynamic unsteady Eyring-Powell dusty nanofluid over a sheet is addressed. The combined effect of Brownian motion and thermophoresis in nanofluid modeling are retained. The Cattaneo-Christov heat flux model is imposed. A set of similarity variables are utilized to form ordinary differential system from the prevailing partial differential equations. The problem of ordinary differential system (ODS is analyzed numerically through Runge-Kutta based shooting method. Graphical results of pertinent parameters on the velocity, temperature and nanoparticle concentration are studied. Skin friction coefficient, local Nusselt and Sherwood number are also addressed with help of graphs and also validated the present solutions with already existing solutions in the form of table. It is found that the thermal relaxation parameter improves the heat transfer rate and minimizes the mass transfer rate. The heat transfer rate is higher in prescribed heat flux (PHF case when compared with prescribed wall temperature (PWT case.
Interfacial stability with mass and heat transfer
International Nuclear Information System (INIS)
Hsieh, D.Y.
1977-07-01
A simplified formulation is presented to deal with interfacial stability problems with mass and heat transfer. For Rayleigh-Taylor stability problems of a liquid-vapor system, it was found that the effect of mass and heat transfer tends to enhance the stability of the system when the vapor is hotter than the liquid, although the classical stability criterion is still valid. For Kelvin-Holmholtz stability problems, however, the classical stability criterion was found to be modified substantially due to the effect of mass and heat transfer
Heat and mass transfer in particulate suspensions
Michaelides, Efstathios E (Stathis)
2013-01-01
Heat and Mass Transfer in Particulate Suspensions is a critical review of the subject of heat and mass transfer related to particulate Suspensions, which include both fluid-particles and fluid-droplet Suspensions. Fundamentals, recent advances and industrial applications are examined. The subject of particulate heat and mass transfer is currently driven by two significant applications: energy transformations –primarily combustion – and heat transfer equipment. The first includes particle and droplet combustion processes in engineering Suspensions as diverse as the Fluidized Bed Reactors (FBR’s) and Internal Combustion Engines (ICE’s). On the heat transfer side, cooling with nanofluids, which include nanoparticles, has attracted a great deal of attention in the last decade both from the fundamental and the applied side and has produced several scientific publications. A monograph that combines the fundamentals of heat transfer with particulates as well as the modern applications of the subject would be...
Conjugate heat and mass transfer in heat mass exchanger ducts
Zhang, Li-Zhi
2013-01-01
Conjugate Heat and Mass Transfer in Heat Mass Exchanger Ducts bridges the gap between fundamentals and recent discoveries, making it a valuable tool for anyone looking to expand their knowledge of heat exchangers. The first book on the market to cover conjugate heat and mass transfer in heat exchangers, author Li-Zhi Zhang goes beyond the basics to cover recent advancements in equipment for energy use and environmental control (such as heat and moisture recovery ventilators, hollow fiber membrane modules for humidification/dehumidification, membrane modules for air purification, desi
Direct geoelectrical evidence of mass transfer at the laboratory scale
Swanson, Ryan D.; Singha, Kamini; Day-Lewis, Frederick D.; Binley, Andrew; Keating, Kristina; Haggerty, Roy
2012-10-01
Previous field-scale experimental data and numerical modeling suggest that the dual-domain mass transfer (DDMT) of electrolytic tracers has an observable geoelectrical signature. Here we present controlled laboratory experiments confirming the electrical signature of DDMT and demonstrate the use of time-lapse electrical measurements in conjunction with concentration measurements to estimate the parameters controlling DDMT, i.e., the mobile and immobile porosity and rate at which solute exchanges between mobile and immobile domains. We conducted column tracer tests on unconsolidated quartz sand and a material with a high secondary porosity: the zeolite clinoptilolite. During NaCl tracer tests we collected nearly colocated bulk direct-current electrical conductivity (σb) and fluid conductivity (σf) measurements. Our results for the zeolite show (1) extensive tailing and (2) a hysteretic relation between σf and σb, thus providing evidence of mass transfer not observed within the quartz sand. To identify best-fit parameters and evaluate parameter sensitivity, we performed over 2700 simulations of σf, varying the immobile and mobile domain and mass transfer rate. We emphasized the fit to late-time tailing by minimizing the Box-Cox power transformed root-mean square error between the observed and simulated σf. Low-field proton nuclear magnetic resonance (NMR) measurements provide an independent quantification of the volumes of the mobile and immobile domains. The best-fit parameters based on σf match the NMR measurements of the immobile and mobile domain porosities and provide the first direct electrical evidence for DDMT. Our results underscore the potential of using electrical measurements for DDMT parameter inference.
Hydrodynamics and mass transfer in trickle leaching process
International Nuclear Information System (INIS)
Jin Suoqing; Xiang Qinfang; Guo Jianzheng
1995-01-01
The initial research results of the hydrodynamic behavior and mass transfer of the trickle leaching process are summarized. It was shown that the dropping mode, the height of uranium ore heap and the flow rate of the dropping fluid affect the mass transfer of the trickle leaching process. Based on the concept of the keeping form of liquid in ore particle bed and the diffusion in porous medium, a mass transfer pattern, i.e. 'double-membrane transfer process' controlled by porous diffusion, was presented and proved for trickle leaching process
Enhancement of heat and mass transfer by cavitation
International Nuclear Information System (INIS)
Zhang, Y N; Du, X Z; Xian, H Z; Zhang, Y N
2015-01-01
In this paper, a brief summary of effects of cavitation on the heat and mass transfer are given. The fundamental studies of cavitation bubbles, including its nonlinearity, rectified heat and mass diffusion, are initially introduced. Then selected topics of cavitation enhanced heat and mass transfer were discussed in details including whales stranding caused by active sonar activity, pool boiling heat transfer, oscillating heat pipe and high intensity focused ultrasound treatment
Ozone mass transfer and kinetics experiments
International Nuclear Information System (INIS)
Bollyky, L.J.; Beary, M.M.
1981-12-01
Experiments were conducted at the Hanford Site to determine the most efficient pH and temperature levels for the destruction of complexants in Hanford high-level defense waste. These complexants enhance migration of radionuclides in the soil and inhibit the growth of crystals in the evaporator-crystallizer. Ozone mass transfer and kinetics tests have been outlined for the determination of critical mass transfer and kinetics parameters of the ozone-complexant reaction
Geoelectrical Measurement of Multi-Scale Mass Transfer Parameters
Energy Technology Data Exchange (ETDEWEB)
Day-Lewis, Frederick David [US Geological Survey, Storrs, CT (United States); Singha, Kamini [Colorado School of Mines, Golden, CO (United States); Johnson, Timothy C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Haggerty, Roy [Oregon State Univ., Corvallis, OR (United States); Binley, Andrew [Lancaster Univ. (United Kingdom); Lane, John W. [US Geological Survey, Storrs, CT (United States)
2014-11-25
Mass transfer affects contaminant transport and is thought to control the efficiency of aquifer remediation at a number of sites within the Department of Energy (DOE) complex. An improved understanding of mass transfer is critical to meeting the enormous scientific and engineering challenges currently facing DOE. Informed design of site remedies and long-term stewardship of radionuclide-contaminated sites will require new cost-effective laboratory and field techniques to measure the parameters controlling mass transfer spatially and across a range of scales. In this project, we sought to capitalize on the geophysical signatures of mass transfer. Previous numerical modeling and pilot-scale field experiments suggested that mass transfer produces a geoelectrical signature—a hysteretic relation between sampled (mobile-domain) fluid conductivity and bulk (mobile + immobile) conductivity—over a range of scales relevant to aquifer remediation. In this work, we investigated the geoelectrical signature of mass transfer during tracer transport in a series of controlled experiments to determine the operation of controlling parameters, and also investigated the use of complex-resistivity (CR) as a means of quantifying mass transfer parameters in situ without tracer experiments. In an add-on component to our grant, we additionally considered nuclear magnetic resonance (NMR) to help parse mobile from immobile porosities. Including the NMR component, our revised study objectives were to: 1. Develop and demonstrate geophysical approaches to measure mass-transfer parameters spatially and over a range of scales, including the combination of electrical resistivity monitoring, tracer tests, complex resistivity, nuclear magnetic resonance, and materials characterization; and 2. Provide mass-transfer estimates for improved understanding of contaminant fate and transport at DOE sites, such as uranium transport at the Hanford 300 Area. To achieve our objectives, we implemented a 3
Geoelectrical Measurement of Multi-Scale Mass Transfer Parameters
Energy Technology Data Exchange (ETDEWEB)
Day-Lewis, Frederick; Singha, Kamini; Haggerty, Roy; Johnson, Tim; Binley, Andrew; Lane, John
2014-01-16
Mass transfer affects contaminant transport and is thought to control the efficiency of aquifer remediation at a number of sites within the Department of Energy (DOE) complex. An improved understanding of mass transfer is critical to meeting the enormous scientific and engineering challenges currently facing DOE. Informed design of site remedies and long-term stewardship of radionuclide-contaminated sites will require new cost-effective laboratory and field techniques to measure the parameters controlling mass transfer spatially and across a range of scales. In this project, we sought to capitalize on the geophysical signatures of mass transfer. Previous numerical modeling and pilot-scale field experiments suggested that mass transfer produces a geoelectrical signature—a hysteretic relation between sampled (mobile-domain) fluid conductivity and bulk (mobile + immobile) conductivity—over a range of scales relevant to aquifer remediation. In this work, we investigated the geoelectrical signature of mass transfer during tracer transport in a series of controlled experiments to determine the operation of controlling parameters, and also investigated the use of complex-resistivity (CR) as a means of quantifying mass transfer parameters in situ without tracer experiments. In an add-on component to our grant, we additionally considered nuclear magnetic resonance (NMR) to help parse mobile from immobile porosities. Including the NMR component, our revised study objectives were to: 1. Develop and demonstrate geophysical approaches to measure mass-transfer parameters spatially and over a range of scales, including the combination of electrical resistivity monitoring, tracer tests, complex resistivity, nuclear magnetic resonance, and materials characterization; and 2. Provide mass-transfer estimates for improved understanding of contaminant fate and transport at DOE sites, such as uranium transport at the Hanford 300 Area. To achieve our objectives, we implemented a 3
International Nuclear Information System (INIS)
Zhang Tao; Liu Xiaohua; Zhang Lun; Jiang Yi
2012-01-01
Highlights: ► Investigates match properties of heat or mass transfer processes in HVAC system. ► Losses are caused by limited transfer ability, flow and parameter mismatching. ► Condition of flow matching is the same heat capacity of the fluids. ► Parameter matching is only reached along the saturation line in air–water system. ► Analytical solutions of heat and mass transfer resistance are derived. - Abstract: Sensible heat exchangers and coupled heat and mass transfer devices between humid air and water/desiccant are commonly used devices in air-conditioning systems. This paper focuses on the match properties of sensible heat transfer processes and coupled heat and mass transfer processes in an effort to understand the reasons for performance limitations in order to optimize system performance. Limited heat transfer capability and flow mismatching resulted in heat resistance of the sensible heat transfer process. Losses occurred during the heat and mass transfer processes due to limited transfer capability, flow mismatching, and parameter mismatching. Flow matching was achieved when the heat capacities of the fluids were identical, and parameter matching could only be reached along the saturation line in air–water systems or the iso-concentration line in air–desiccant systems. Analytical solutions of heat transfer resistance and mass transfer resistance were then derived. The heat and mass transfer process close to the saturation line is recommended, and heating sprayed water resulted in better humidification performance than heating inlet air in the air humidifier.
Mass Transfer in Mira-Type Binaries
Directory of Open Access Journals (Sweden)
Mohamed S.
2012-06-01
Full Text Available Detached, symbiotic binaries are generally assumed to interact via Bondi-Hoyle-Littleton (BHL wind accretion. However, the accretion rates and outflow geometries that result from this mass-transfer mechanism cannot adequately explain the observations of the nearest and best studied symbiotic binary, Mira, or the formation of some post-AGB binaries, e.g. barium stars. We propose a new mass-transfer mode for Mira-type binaries, which we call ‘wind Roche-lobe overflow’ (WRLOF, and which we demonstrate with 3D hydrodynamic simulations. Importantly, we show that the circumstellar outflows which result from WRLOF tend to be highly aspherical and strongly focused towards the binary orbital plane. Furthermore, the subsequent mass-transfer rates are at least an order of magnitude greater than the analogous BHL values. We discuss the implications of these results for the shaping of bipolar (proto-planetary nebulae and other related systems.
Second Law Analysis in Convective Heat and Mass Transfer
Directory of Open Access Journals (Sweden)
A. Ben Brahim
2006-02-01
Full Text Available This paper reports the numerical determination of the entropy generation due to heat transfer, mass transfer and fluid friction in steady state for laminar double diffusive convection, in an inclined enclosure with heat and mass diffusive walls, by solving numerically the mass, momentum, species conservation and energy balance equations, using a Control Volume Finite-Element Method. The influences of the inclination angle, the thermal Grashof number and the buoyancy ratio on total entropy generation were investigated. The irreversibilities localization due to heat transfer, mass transfer and fluid friction is discussed for three inclination angles at a fixed thermal Grashof number.
International Nuclear Information System (INIS)
Sieniutycz, S.; Berry, R.S.
1992-01-01
For coupled transfer of the energy and mass in a multicomponent system at mechanical equilibrium a simple thermodynamic theory is developed, and the damped wave equations of change are derived. We show that under nonstationary conditions, where relaxation of diffusive fluxes is essential, the evolution of the distributed coupled transfer of the energy and mass follows the path that minimizes the difference between the total entropy generated within the system and that exchanged by the system. The principle is also valid in the limit in which flux relaxation effects are negligible and the heat and mass transfer, whether steady or not, obeys Onsager's generalization of the Fourier and Fick laws. For coupled steady-state processes the principle goes into that of Onsager, yielding his phenomenological equations. In contrast to the local steady-state nature of Onsager's principle the new principle is global, valid for both stationary and transient situations, and requires no frozen fields. For an isolated, distributed system, in which transient relaxation to equilibrium is the only possible process, the principle implies the least possible increase of the system entropy between any two successive configurations
Mass transfer in horizontal flow channels with thermal gradients
International Nuclear Information System (INIS)
Bendrich, G.; Shemilt, L.W.
1997-01-01
Mass transfer to a wall of a horizontal rectangular channel reactor was investigated by the limiting current technique for Reynolds numbers ranging from 200 to 32000. Overall mass transfer coefficients at various mass transfer surface angles were obtained while the reactor was operated under isothermal and non-isothermal conditions. Dimensionless correlations were developed for isothermal flows from 25 to 55 o C and for non-isothermal flows with applied temperature differences up to 30 o C. In the laminar flow range natural convection dominated, but under turbulent conditions combined natural and forced convection prevailed. Mass transfer was approximately doubled under optimum selection of channel surface rotation, temperature gradient and flow rate. (author)
International Nuclear Information System (INIS)
2015-01-01
The conference covered various aspects of heat and mass transfer like Aero-thermodynamics, Atmospheric flows, Biological heat and mass transfer, Combustion and reactive flows, Cryogenics, Electronic and photonic cooling, Energy engineering, Environmental engineering, Experimental techniques, Heat transfer enhancement, Heat transfer equipment's, Heat transfer in nuclear applications, Mass transfer, Materials processing and manufacturing, Microscale and nanoscale transport, Multiphase transport and phase change, Multi mode heat transfer, Numerical methods, Refrigeration and air conditioning, Space heat transfer, Transport phenomena in porous media, and Turbulent transport. Papers relevant to INIS are indexed separately
Convective mass transfer around a dissolving bubble
Duplat, Jerome; Grandemange, Mathieu; Poulain, Cedric
2017-11-01
Heat or mass transfer around an evaporating drop or condensing vapor bubble is a complex issue due to the interplay between the substrate properties, diffusion- and convection-driven mass transfer, and Marangoni effects, to mention but a few. In order to disentangle these mechanisms, we focus here mainly on the convective mass transfer contribution in an isothermal mass transfer problem. For this, we study the case of a millimetric carbon dioxide bubble which is suspended under a substrate and dissolved into pure liquid water. The high solubility of CO2 in water makes the liquid denser and promotes a buoyant-driven flow at a high (solutal) Rayleigh number (Ra˜104 ). The alteration of p H allows the concentration field in the liquid to be imaged by laser fluorescence enabling us to measure both the global mass flux (bubble volume, contact angle) and local mass flux around the bubble along time. After a short period of mass diffusion, where the boundary layer thickens like the square root of time, convection starts and the CO2 is carried by a plume falling at constant velocity. The boundary layer thickness then reaches a plateau which depends on the bubble cross section. Meanwhile the plume velocity scales like (dV /d t )1 /2 with V being the volume of the bubble. As for the rate of volume loss, we recover a constant mass flux in the diffusion-driven regime followed by a decrease in the volume V like V2 /3 after convection has started. We present a model which agrees well with the bubble dynamics and discuss our results in the context of droplet evaporation, as well as high Rayleigh convection.
Neutrino masses in the minimal gauged (B -L ) supersymmetry
Yan, Yu-Li; Feng, Tai-Fu; Yang, Jin-Lei; Zhang, Hai-Bin; Zhao, Shu-Min; Zhu, Rong-Fei
2018-03-01
We present the radiative corrections to neutrino masses in a minimal supersymmetric extension of the standard model with local U (1 )B -L symmetry. At tree level, three tiny active neutrinos and two nearly massless sterile neutrinos can be obtained through the seesaw mechanism. Considering the one-loop corrections to the neutrino masses, the numerical results indicate that two sterile neutrinos obtain KeV masses and the small active-sterile neutrino mixing angles. The lighter sterile neutrino is a very interesting dark matter candidate in cosmology. Meanwhile, the active neutrinos mixing angles and mass squared differences agree with present experimental data.
Mass transfer in a salt repository
International Nuclear Information System (INIS)
Pigford, T.H.; Chambre, P.L.
1985-05-01
To meet regulatory requirements for radioactive waste in a salt repository it is necessary to predict the rates of corrosion of the waste container, the release rates of radionuclides from the waste package, and the cumulative release of radionuclides into the accessible environment. The mechanisms that may control these rates and an approach to predicting these rates from mass-transfer theory are described. This new mechanistic approach is suggested by three premises: (a) a brine inclusion originally in a salt crystal moves along grain boundaries after thermal-induced migration out of the crystal, (b) brine moves along a grain boundary under the influence of a pressure gradient, and (c) salt surrounding a heat-generating waste package will soon creep and consolidate as a monolithic medium surrounding and in contact with the waste package. After consolidation there may be very little migration of intergranular and intragranular brine to the waste package. The corrosion rate of the waste container may then be limited by the rate at which brine reaches the container and may be calculable from mass-transfer theory, and the rate at which dissolved radionuclides leave the waste package may be limited by molecular diffusion in intragranular brine and may be calculable from mass-transfer theory. If porous nonsalt interbeds intersect the waste-package borehole, the release rate of dissolved radionuclides to interbed brine may also be calculable from mass-transfer theory. The logic of these conclusions is described, as an aid in formulating the calculations that are to be made
Overall mass-transfer coefficients in non-linear chromatography
DEFF Research Database (Denmark)
Mollerup, Jørgen; Hansen, Ernst
1998-01-01
In case of mass transfer where concentration differences in both phases must be taken into account, one may define an over-all mass-transfer coefficient basd on the apparent over-all concentration difference. If the equilibrium relationship is linear, i.e. in cases where a Henry´s law relationshi...
Liquid-gas mass transfer at drop structures
DEFF Research Database (Denmark)
Matias, Natércia; Nielsen, Asbjørn Haaning; Vollertsen, Jes
2017-01-01
-water mass transfer, little is known about hydrogen sulfide emission under highly turbulent conditions (e.g., drop structures, hydraulic jumps). In this study, experimental work was carried out to analyze the influence of characteristics of drops on reaeration. Physical models were built, mimicking typical...... sewer drop structures and allowing different types of drops, drop heights, tailwater depths and flow rates. In total, 125 tests were performed. Based on their results, empirical expressions translating the relationship between the mass transfer of oxygen and physical parameters of drop structures were...... established. Then, by applying the two-film theory with two-reference substances, the relation to hydrogen sulfide release was defined. The experiments confirmed that the choice of the type of drop structure is critical to determine the uptake/emission rates. By quantifying the air-water mass transfer rates...
A mass transfer in heterogeneous systems by the adsorption method (
Directory of Open Access Journals (Sweden)
N. Bošković-Vragolović
2009-01-01
Full Text Available A mass transfer coefficient between: a liquid and single sphere and a liquid and column wall in packed and fluidized beds of a spherical inert particle have been studied experimentally using the adsorption method. The experiments were conducted in a column 40 mm in diameter for packed and fluidized beds, and in a two-dimensional column 140 mm×10 mm for the flow past single sphere. In all runs, the mass transfer rates were determined in the presence of spherical glass particles, 3 mm in diameter, for packed and fluidized beds. The mass transfer data were obtained by studying transfer for flow past single sphere, 20 mm in diameter. This paper discusses the possibilities of application of the adsorption method for fluid flow visualization. Local and average mass transfer coefficients were determined from the color intensity of the surface of the foils of silica gel. Correlations, Sh = f(Re and jD = f(Re, were derived using the mass transfer coefficient data.
THE ELECTRONIC COURSE OF HEAT AND MASS TRANSFER
Directory of Open Access Journals (Sweden)
Alexander P. Solodov
2013-01-01
Full Text Available The Electronic course of heat and mass transfer in power engineering is presented containing the full Electronic book as the structured hypertext document, the full set of Mathcad-documents with the whole set of educative computer models of heat and mass transfer, the computer labs, and selected educational presentations.
Heat or mass transfer from an open cavity
Kuiken, H.K.
1978-01-01
This paper presents a mathematical model for heat or mass transfer from an open cavity. It is assumed that the Péclet number, based on conditions at the cavity, and the Prandtl number are both large. The model assumes heat- or mass-transfer boundary layers at the rim of the cavity vortex flow. Heat
Fluid dynamics and mass transfer in a gas centrifuge
International Nuclear Information System (INIS)
Conlisk, A.T.; Foster, M.R.; Walker, J.D.A.
1982-01-01
The fluid motion, temperature distribution and the mass-transfer problem of a binary gas mixture in a rapidly rotating centrifuge are investigated. Solutions for the velocity, temperature and mass-fraction fields within the centrifuge are obtained for mechanically or thermally driven centrifuges. For the mass-transfer problem, a detailed analysis of the fluid-mechanical boundary layers is required, and, in particular, mass fluxes within the boundary layers are obtained for a wide range of source-sink geometries. Solutions to the mass-transfer problem are obtained for moderately and strongly forced flows in the container; the dependence of the separation (or enrichment) factor on centrifuge configuration, rotational speed and fraction of the volumetric flow rate extracted at the product port (the cut) are predicted. (author)
Using White Dwarf Companions of Blue Stragglers to Constrain Mass Transfer Physics
Gosnell, Natalie M.; Leiner, Emily; Geller, Aaron M.; Knigge, Christian; Mathieu, Robert D.; Sills, Alison; Leigh, Nathan
2018-06-01
Complete membership studies of old open clusters reveal that 25% of the evolved stars follow pathways in stellar evolution that are impacted by binary evolution. Recent studies show that the majority of blue straggler stars, traditionally defined to be stars brighter and bluer than the corresponding main sequence turnoff, are formed through mass transfer from a giant star onto a main sequence companion, resulting in a white dwarf in a binary system with a blue straggler. We will present constraints on the histories and mass transfer efficiencies for two blue straggler-white dwarf binaries in open cluster NGC 188. The constraints are a result of measuring white dwarf cooling temperatures and surface gravities with HST COS far-ultraviolet spectroscopy. This information sets both the timeline for mass transfer and the stellar masses in the pre-mass transfer binary, allowing us to constrain aspects of the mass transfer physics. One system is formed through Case C mass transfer, leaving a CO-core white dwarf, and provides an interesting test case for mass transfer from an asymptotic giant branch star in an eccentric system. The other system formed through Case B mass transfer, leaving a He-core white dwarf, and challenges our current understanding of the expected regimes for stable mass transfer from red giant branch stars.
FCNC Effects in a Minimal Theory of Fermion Masses
Buras, Andrzej J; Pokorski, Stefan; Ziegler, Robert
2011-01-01
As a minimal theory of fermion masses we extend the SM by heavy vectorlike fermions, with flavor-anarchical Yukawa couplings, that mix with chiral fermions such that small SM Yukawa couplings arise from small mixing angles. This model can be regarded as an effective description of the fermionic sector of a large class of existing flavor models and thus might serve as a useful reference frame for a further understanding of flavor hierarchies in the SM. Already such a minimal framework gives rise to FCNC effects through exchange of massive SM bosons whose couplings to the light fermions get modified by the mixing. We derive general formulae for these corrections and discuss the bounds on the heavy fermion masses. Particularly stringent bounds, in a few TeV range, come from the corrections to the Z couplings.
Determination and correlation of mass transfer coefficients in a stirred cell
International Nuclear Information System (INIS)
Herranz, J.; Bloxom, S.R.; Keeler, J.B.; Roth, S.R.
1975-01-01
In the proposed Molten Salt Breeder Reactor flowsheet, a fraction of the rare earth fission products is removed from the fuel salt in mass transfer cells. To obtain design parameters for this extraction, the effect of cell size, blade diameter, phase volume, and agitation rate on the mass transfer for a high density ratio system (mercury/water) in nondispersing square cross section contactors was determined. Aqueous side mass transfer coefficients were measured by polarography over a wide range of operating conditions. Correlations for the experimental mass transfer coefficients as functions of the operating parameters are presented. Several techniques for measuring mercury-side mass transfer coefficients were evaluated and a new one is recommended
Mass transfer parameters of celeriac during vacuum drying
Beigi, Mohsen
2017-04-01
An accurate prediction of moisture transfer parameters is very important for efficient mass transfer analysis, accurate modelling of drying process, and better designing of new dryers and optimization of existing drying process. The present study aimed to investigate the influence of temperature (e.g., 55, 65 and 75 °C) and chamber pressure (e.g., 0.1, 3, 7, 10, 13 and 17 kPa) on effective diffusivity and convective mass transfer coefficient of celeriac slices during vacuum drying. The obtained Biot number indicated that the moisture transfer in the celeriac slices was controlled by both internal and external resistance. The effective diffusivity obtained to be in the ranges of 7.5231 × 10-10-3.8015 × 10-9 m2 s-1. The results showed that the diffusivity increased with increasing temperature and decreasing pressure. The mass transfer coefficient values varied from 4.6789 × 10-7 to 1.0059 × 10-6 m s-1, and any increment in drying temperature and pressure caused an increment in the coefficient.
Heat and mass transfer enhancement in absorbing processes
International Nuclear Information System (INIS)
Hijikata, Kunio; Lee, S.K.
1993-01-01
The key to improving the performance of absorption-type heat machines lies in the enhancement of the mass transfer of the vapor into the absorbant solution, since the mass diffusivity in the solution is very small compared to the thermal diffusivity. The absorption process is influenced by many factors including physical properties of the fluids, the flow pattern and others, especially the velocity profile near the interface is the most important. From these stand points, the heat and mass transfer in the absorption was investigated by following three steps. First, an augmentation of the absorption to a liquid film flowing in groove was theoretically investigated, in which the interface between the vapor and liquid film is cooled by the grooved surfaces. Secondly, systematical experiments were carried out on several factors that affect the absorption process, which were the cooling wall temperature, the inlet solution subcooling, and the fin configuration. Finally, a numerical study of the heat and mass transfer enhancement due to flow agitation by the periodically grooved channel was conducted. That flow realized by fabricating ridges on the fin surface. A secondary flow due to these ridges is expected to enhance the heat and mass transfer. These results were compared with experimental ones. (orig.)
Mass Transfer Operations for the Practicing Engineer
Theodore, Louis
2011-01-01
Part of the Essential Engineering Calculations Series, this book presents step-by-step solutions of the basic principles of mass transfer operations, including sample problems and solutions and their applications, such as distillation, absorption, and stripping. Presenting the subject from a strictly pragmatic point of view, providing both the principles of mass transfer operations and their applications, with clear instructions on how to carry out the basic calculations needed, the book also covers topics useful for readers taking their professional exams.
Lab. experiments of mass transfer in the London clay
International Nuclear Information System (INIS)
Bourke, P.J.; Gilling, D.; Jefferies, N.L.; Lineham, T.R.; Lever, D.A.
1989-01-01
Aqueous phase mass transfer through the rocks surrounding a radioactive waste repository will take place by diffusion and convection. This paper presents a comprehensive set of measurements of the mass transfer characteristics for a single, naturally occurring, clay. These data are compared with the results predicted by mathematical models of mass transport in porous media, in order to build confidence in these models
Devices with extended area structures for mass transfer processing of fluids
TeGrotenhuis, Ward E.; Wegeng, Robert S.; Whyatt, Greg A.; King, David L.; Brooks, Kriston P.; Stenkamp, Victoria S.
2009-04-21
A microchannel device includes several mass transfer microchannels to receive a fluid media for processing at least one heat transfer microchannel in fluid communication with a heat transfer fluid defined by a thermally conductive wall, and at several thermally conductive fins each connected to the wall and extending therefrom to separate the mass transfer microchannels from one another. In one form, the device may optionally include another heat transfer microchannel and corresponding wall that is positioned opposite the first wall and has the fins and the mass transfer microchannels extending therebetween.
Final Report: Geoelectrical Measurement of Multi-Scale Mass Transfer Parameters
Energy Technology Data Exchange (ETDEWEB)
Haggerty, Roy [Oregon State Univ., Corvallis, OR (United States); Day-Lewis, Fred [U.S. Geological Survey, Storrs, CT (United States); Singha, Kamini [Colorado School of Mines, Golden, CO (United States); Johnson, Timothy [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Binley, Andrew [Lancaster Univ. (United Kingdom); Lane, John [U.S. Geological Survey, Storrs, CT (United States)
2014-03-20
Mass transfer affects contaminant transport and is thought to control the efficiency of aquifer remediation at a number of sites within the Department of Energy (DOE) complex. An improved understanding of mass transfer is critical to meeting the enormous scientific and engineering challenges currently facing DOE. Informed design of site remedies and long-term stewardship of radionuclide-contaminated sites will require new cost-effective laboratory and field techniques to measure the parameters controlling mass transfer spatially and across a range of scales. In this project, we sought to capitalize on the geophysical signatures of mass transfer. Previous numerical modeling and pilot-scale field experiments suggested that mass transfer produces a geoelectrical signature—a hysteretic relation between sampled (mobile-domain) fluid conductivity and bulk (mobile + immobile) conductivity—over a range of scales relevant to aquifer remediation. In this work, we investigated the geoelectrical signature of mass transfer during tracer transport in a series of controlled experiments to determine the operation of controlling parameters, and also investigated the use of complex-resistivity (CR) as a means of quantifying mass transfer parameters in situ without tracer experiments. In an add-on component to our grant, we additionally considered nuclear magnetic resonance (NMR) to help parse mobile from immobile porosities. Including the NMR component, our revised study objectives were to: 1. Develop and demonstrate geophysical approaches to measure mass-transfer parameters spatially and over a range of scales, including the combination of electrical resistivity monitoring, tracer tests, complex resistivity, nuclear magnetic resonance, and materials characterization; and 2. Provide mass-transfer estimates for improved understanding of contaminant fate and transport at DOE sites, such as uranium transport at the Hanford 300 Area. To achieve our objectives, we implemented a 3
Enhancement of combined heat and mass transfer in a vertical-tube heat and mass exchanger
International Nuclear Information System (INIS)
Webb, R.L.; Perez-Blanco, H.
1986-01-01
This paper studies enhancement of heat and mass transfer between a countercurrent, gravity-drained water film and air flowing in a vertical tube. The enhancement technique employed is spaced, transverse wires placed in the air boundary layer, near the air--water interface. Heat transfer correlations for turbulent, single-phase heat transfer in pipes having wall-attached spaced ribs are used to select the preferred wire diameter, and to predict the gas phase heat and mass transfer coefficients. Tests were run with two different radial placements of the rib roughness: (1) at the free surface of the liquid film, and (2) the base of the roughness displaced 0.51 mm into the air flow. The authors hypothesize that the best heat/mass transfer and friction performance will be obtained with the roughness at the surface of the water film. Experiments conducted with both roughness placements show that the authors' hypothesis is correct. The measured heat/mass transfer enhancement agreed very closely with the predicted values. A unique feature of the enhancement concept is that it does not require surface wetting of the enhancement device to provide enhancement
DEFF Research Database (Denmark)
Nielsen, Anders Michael; Nielsen, Lars Peter; Feilberg, Anders
2009-01-01
A membrane inlet mass spectrometer (MIMS) was used in combination with a developed computer model to study and improve management of a biofilter (BF) treating malodorous ventilation air from a meat rendering facility. The MIMS was used to determine percentage removal efficiencies (REs) of selected...... sulfur gases and to provide toluene retention profiles for the model to determine the air velocity and overall mass-transfer coefficient of toluene. The mass-transfer coefficient of toluene was used as a reference for determining the mass transfer of sulfur gases. By presenting the model to scenarios...... of a filter bed with a consortium of effective sulfur oxidizers, the most likely mechanism for incomplete removal of sulfur compounds from the exhaust air was elucidated. This was found to be insufficient mass transfer and not inadequate bacterial activity as anticipated by the manager of the BF. Thus...
Impact of kinetic mass transfer on free convection in a porous medium
Lu, Chunhui; Shi, Liangsheng; Chen, Yiming; Xie, Yueqing; Simmons, Craig T.
2016-05-01
We investigate kinetic mass transfer effects on unstable density-driven flow and transport processes by numerical simulations of a modified Elder problem. The first-order dual-domain mass transfer model coupled with a variable-density-flow model is employed to describe transport behavior in porous media. Results show that in comparison to the no-mass-transfer case, a higher degree of instability and more unstable system is developed in the mass transfer case due to the reduced effective porosity and correspondingly a larger Rayleigh number (assuming permeability is independent on the mobile porosity). Given a constant total porosity, the magnitude of capacity ratio (i.e., immobile porosity/mobile porosity) controls the macroscopic plume profile in the mobile domain, while the magnitude of mass transfer timescale (i.e., the reciprocal of the mass transfer rate coefficient) dominates its evolution rate. The magnitude of capacity ratio plays an important role on the mechanism driving the mass flux into the aquifer system. Specifically, for a small capacity ratio, solute loading is dominated by the density-driven transport, while with increasing capacity ratio local mass transfer dominated solute loading may occur at later times. At significantly large times, however, both mechanisms contribute comparably to solute loading. Sherwood Number could be a nonmonotonic function of mass transfer timescale due to complicated interactions of solute between source zone, mobile zone and immobile zone in the top boundary layer, resulting in accordingly a similar behavior of the total mass. The initial assessment provides important insights into unstable density-driven flow and transport in the presence of kinetic mass transfer.
Introduction to computational mass transfer with applications to chemical engineering
Yu, Kuo-Tsung
2017-01-01
This book offers an easy-to-understand introduction to the computational mass transfer (CMT) method. On the basis of the contents of the first edition, this new edition is characterized by the following additional materials. It describes the successful application of this method to the simulation of the mass transfer process in a fluidized bed, as well as recent investigations and computing methods for predictions for the multi-component mass transfer process. It also demonstrates the general issues concerning computational methods for simulating the mass transfer of the rising bubble process. This new edition has been reorganized by moving the preparatory materials for Computational Fluid Dynamics (CFD) and Computational Heat Transfer into appendices, additions of new chapters, and including three new appendices on, respectively, generalized representation of the two-equation model for the CMT, derivation of the equilibrium distribution function in the lattice-Boltzmann method, and derivation of the Navier-S...
Karwa, Rajendra
2017-01-01
This textbook presents the classical treatment of the problems of heat transfer in an exhaustive manner with due emphasis on understanding of the physics of the problems. This emphasis is especially visible in the chapters on convective heat transfer. Emphasis is laid on the solution of steady and unsteady two-dimensional heat conduction problems. Another special feature of the book is a chapter on introduction to design of heat exchangers and their illustrative design problems. A simple and understandable treatment of gaseous radiation has been presented. A special chapter on flat plate solar air heater has been incorporated that covers thermo-hydraulic modeling and simulation. The chapter on mass transfer has been written looking specifically at the needs of the students of mechanical engineering. The book includes a large number and variety of solved problems with supporting line diagrams. The author has avoided duplicating similar problems, while incorporating more application-based examples. All the end-...
Mass transfer and transport in salt repositories
International Nuclear Information System (INIS)
Pigford, T.H.; Chambre, P.L.; Lee, W.W.L.
1989-02-01
Salt is a unique rock isolation of nuclear waste because it is ''dry'' and nearly impermeable. In this paper we summarize some mass-transfer and transport analyses of salt repositories. First we analyses brine migration. Heating by high-level waste can cause brine in grain boundaries to move due to pressure-gradients. We analyze brine migration treating salt as a thermoelastic solid and found that brine migration is transient and localized. We use previously developed techniques to estimate release rates from waste packages by diffusion. Interbeds exist in salt and may be conduits for radionuclide migration. We analyze steady-state migration due to brine flow in the interbed, as a function of the Peclet number. Then we analyze transient mass transfer, both into the interbed and directly to salt, due only to diffusion. Finally we compare mass transfer rates of a waste cylinder in granite facing a fracture and in salt facing an interbed. In all cases, numerical illustrations of the analytic solution are given. 10 refs., 4 figs., 3 tabs
Saponification reaction system: a detailed mass transfer coefficient determination.
Pečar, Darja; Goršek, Andreja
2015-01-01
The saponification of an aromatic ester with an aqueous sodium hydroxide was studied within a heterogeneous reaction medium in order to determine the overall kinetics of the selected system. The extended thermo-kinetic model was developed compared to the previously used simple one. The reaction rate within a heterogeneous liquid-liquid system incorporates a chemical kinetics term as well as mass transfer between both phases. Chemical rate constant was obtained from experiments within a homogeneous medium, whilst the mass-transfer coefficient was determined separately. The measured thermal profiles were then the bases for determining the overall reaction-rate. This study presents the development of an extended kinetic model for considering mass transfer regarding the saponification of ethyl benzoate with sodium hydroxide within a heterogeneous reaction medium. The time-dependences are presented for the mass transfer coefficient and the interfacial areas at different heterogeneous stages and temperatures. The results indicated an important role of reliable kinetic model, as significant difference in k(L)a product was obtained with extended and simple approach.
MASS TRANSFER KINETICS AND EFFECTIVE DIFFUSIVITIES DURING COCOA ROASTING
Directory of Open Access Journals (Sweden)
Y. M. BAGHDADI
2017-01-01
Full Text Available The current studies investigated the effects of temperature and moisture addition on the mass transfer kinetics of cocoa nibs during roasting. Experiments were carried out by roasting 500 gm of cocoa nibs inside an air ventilated oven at three temperature levels (120°C, 140°C and 160°C under medium air flowrate for one hour. Two types of samples were prepared namely the raw and soaked nib samples. The soaked nib samples were prepared by soaking the raw nibs in 200 ml of water at room temperature for 5 and 10 hours. Mathematical modelling was carried out to model the mass transfer process using semi-empirical models. Modelling showed that both Page and two-term models were able to give close fitting between the experimental and predicted values. Effective diffusivity values were estimated in the order of magnitude of 10-5 m2/s for the mass transfer process. Results obtained from these studies fill the current knowledge gap on the mass transfer kinetics of cocoa roasting.
Two-loop mass splittings in electroweak multiplets: Winos and minimal dark matter
McKay, James; Scott, Pat
2018-03-01
The radiatively-induced splitting of masses in electroweak multiplets is relevant for both collider phenomenology and dark matter. Precision two-loop corrections of O (MeV ) to the triplet mass splitting in the wino limit of the minimal supersymmetric standard model can affect particle lifetimes by up to 40%. We improve on previous two-loop self-energy calculations for the wino model by obtaining consistent input parameters to the calculation via two-loop renormalization-group running, and including the effect of finite light quark masses. We also present the first two-loop calculation of the mass splitting in an electroweak fermionic quintuplet, corresponding to the viable form of minimal dark matter (MDM). We place significant constraints on the lifetimes of the charged and doubly-charged fermions in this model. We find that the two-loop mass splittings in the MDM quintuplet are not constant in the large-mass limit, as might naively be expected from the triplet calculation. This is due to the influence of the additional heavy fermions in loop corrections to the gauge boson propagators.
Lee, Jung Gil
2017-11-03
In order to improve water production of membrane distillation (MD), the development of high performance membrane having better mass transfer and enhancement of convection heat transfer in MD module have been continuously investigated. This paper presents the relationship between the heat and mass transfer resistance across the membrane and the performance improvement. Various ranges of mass transfer coefficient (MTC) from normal (0.3×10−6 to 2.1×10−6kg/m2sPa: currently available membranes) to high (>2.1×10−6kg/m2sPa: membranes under development) were simulated using an experimentally validated model at different ranges of convection heat transfer by varying the inlet flow rates and spacer enhancement factor. The effect of mass transfer and convection heat transfer on the MD performance parameters including temperature polarization coefficient (TPC), mean permeate flux, and specific energy consumption were investigated in a direct contact MD (DCMD) configuration. Results showed that improving the MTC at the low ranges is more important than that at the high ranges where the heat transfer resistance becomes dominant and hence the convection heat transfer coefficient must be increased. Therefore, an effort on designing MD modules using feed and permeate spacers and controlling the membrane surface roughness to increase the convection heat transfer and TPC in the channel aiming to enhance the flux is required because the currently developed mass transfer has almost reached the critical point.
Proton Transfer Time-of-Flight Mass Spectrometer
Energy Technology Data Exchange (ETDEWEB)
Watson, Thomas B. [Brookhaven National Lab. (BNL), Upton, NY (United States)
2016-03-01
The Proton Transfer Reaction Mass Spectrometer (PTRMS) measures gas-phase compounds in ambient air and headspace samples before using chemical ionization to produce positively charged molecules, which are detected with a time-of-flight (TOF) mass spectrometer. This ionization method uses a gentle proton transfer reaction method between the molecule of interest and protonated water, or hydronium ion (H_{3}O^{+}), to produce limited fragmentation of the parent molecule. The ions produced are primarily positively charged with the mass of the parent ion, plus an additional proton. Ion concentration is determined by adding the number of ions counted at the molecular ion’s mass-to-charge ratio to the number of air molecules in the reaction chamber, which can be identified according to the pressure levels in the reaction chamber. The PTRMS allows many volatile organic compounds in ambient air to be detected at levels from 10–100 parts per trillion by volume (pptv). The response time is 1 to 10 seconds.
Solubility is the most important mass transfer factor
International Nuclear Information System (INIS)
Slobodov, A.A.; Zarembo, V.I.
1992-01-01
The existence of the quantitative correlation between mass transfer and equilibrium solubility of corrosion products of construction materials in water circuits of power plants is shown. Thermodynamic and mathematical methods of modeling and calculating for these processes are developed. The results for iron based materials - aqueous solution systems in a wide range of temperature, pH, oxygen-hydrogen concentrations are presented. The optimization conditions for mass transfer, sedimentation of corrosion products for BWR, PWR reactors, etc. have been obtained
Mass transfer dynamics in double degenerate binary systems
International Nuclear Information System (INIS)
Dan, M; Rosswog, S; Brueggen, M
2009-01-01
We present a numerical study of the mass transfer dynamics prior to the gravitational wave-driven merger of a double white dwarf system. Recently, there has been some discussion about the dynamics of these last stages, different methods seemed to provide qualitatively different results. While earlier SPH simulations indicated a very quick disruption of the binary on roughly the orbital time scale, more recent grid-based calculations find long-lived mass transfer for many orbital periods. Here we demonstrate how sensitive the dynamics of this last stage is to the exact initial conditions. We show that, after a careful preparation of the initial conditions, the reportedly short-lived systems undergo mass transfer for many dozens of orbits. The reported numbers of orbits are resolution-biased and therefore represent only lower limits to what is realized in nature. Nevertheless, the study shows convincingly the convergence of different methods to very similar results.
Limit behavior of mass critical Hartree minimization problems with steep potential wells
Guo, Yujin; Luo, Yong; Wang, Zhi-Qiang
2018-06-01
We consider minimizers of the following mass critical Hartree minimization problem: eλ(N ) ≔inf {u ∈H1(Rd ) , ‖u‖2 2=N } Eλ(u ) , where d ≥ 3, λ > 0, and the Hartree energy functional Eλ(u) is defined by Eλ(u ) ≔∫Rd|∇u (x ) |2d x +λ ∫Rdg (x ) u2(x ) d x -1/2 ∫Rd∫Rdu/2(x ) u2(y ) |x -y |2 d x d y . Here the steep potential g(x) satisfies 0 =g (0 ) =infRdg (x ) ≤g (x ) ≤1 and 1 -g (x ) ∈Ld/2(Rd ) . We prove that there exists a constant N* > 0, independent of λg(x), such that if N ≥ N*, then eλ(N) does not admit minimizers for any λ > 0; if 0 N N*, then there exists a constant λ*(N) > 0 such that eλ(N) admits minimizers for any λ > λ*(N) and eλ(N) does not admit minimizers for 0 N). For any given 0 N N*, the limit behavior of positive minimizers for eλ(N) is also studied as λ → ∞, where the mass concentrates at the bottom of g(x).
Mass transfer in stellar X-ray sources
International Nuclear Information System (INIS)
Verbunt, F.
1982-01-01
This thesis deals with mass transfer in the binary stars that emit X-rays. Optical observations on two sources are presented: 2A0311-227 and Cen X-4. The transferred matter will often enter a gaseous disk around the compact star, and spiral inwards slowly through this disk. The conditions for the formation of such a disk are investigated and the equations governing its structure are presented. Different models are discussed and it is concluded that different models lead to very similar results for those regions of the disk where gas pressure is more important than radiative pressure, and that these results agree fairly well with observations. No consistent model has been constructed as yet for the region where radiative pressure is dominant. Theoretically one predicts that the optical light emitted by a disk around a neutron star is mainly caused by X-ray photons from the immediate surroundings of the neutron star that hit the outer disk surface, are absorbed, thermalised, and re-emitted in the optical and ultraviolet regions of the spectrum. This expectation is verified by comparison with the collected observational data of low-mass X-ray binaries. Finally the author investigates which mechanism is responsible for the mass transfer in systems where the mass-losing star is less massive than the sun. (Auth.)
Mass-transfer characterization in a parallel-plate electrochemical reactor with convergent flow
International Nuclear Information System (INIS)
Colli, A.N.; Bisang, J.M.
2013-01-01
Highlights: • A convergent laminar flow enhances and becomes more uniform the mass-transfer rate. • The mass-transfer rate is increased under convergent turbulent flow conditions. • The mass-transfer rate under convergent laminar flow can be theoretically predicted. • A convergent duct improves the reactor behaviour and the concept is easily applicable. -- Abstract: A continuous reduction in the cross-section area is analysed as a means of improving mass-transfer in a parallel-plate electrochemical reactor. Experimental local mass-transfer coefficients along the electrode length are reported for different values of the convergent ratio and Reynolds numbers, using the reduction of ferricyanide as a test reaction. The Reynolds numbers evaluated at the reactor inlet range from 85 to 4600 with interelectrode gaps of 2 and 4 mm. The convergent flow improves the mean mass-transfer coefficient by 10–60% and mass-transfer distribution under laminar flow conditions becomes more uniform. The experimental data under laminar flow conditions are compared with theoretical calculations obtained by a computational fluid dynamics software and also with an analytical simplified model. A suitable agreement is observed between both theoretical treatments and with the experimental results. The pressure drop across the reactor is reported and compared with theoretical predictions
MASS TRANSFER IN PORE STRUCTURES OF SUPPORTED CATALYSTS
Directory of Open Access Journals (Sweden)
F.R.C. Silva
1997-09-01
Full Text Available The effects of gas-solid interaction and mass transfer in fixed-bed systems of supported catalysts were analyzed for g -Al2O3 (support and Cu/g -Al2O3 (catalyst systems. Evaluations of the mass transfer coefficients in the macropores and of the diffusivity in the micropores, as formed by the crystallite agglomerates of the metallic phases, were obtained. Dynamic experiments with gaseous tracers permitted the quantification of the parameters based on models for these two pore structures. With a flow in a range of 18 cm3 s-1 to 39.98 cm3 s-1 at 45oC, 65oC and 100oC, mass transfer coefficients km =4.33x10-4 m s-1 to 7.38x10-4 m s-1 for macropore structures and diffusivities Dm =1.29x10-11 m2 s-1 to 5.35x10-11 m2 s-1 for micropore structures were estimated
Molecular engineering problems in heat and mass transfer
International Nuclear Information System (INIS)
Kotake, S.
1991-01-01
As for developing, manufacturing and applying new materials of advanced functions such as high-performance devices and high-temperature materials, fundamental understanding of the phenomena from the standpoint of molecular and atomic levels has been required. In these problems, the processes of heat and mass transfer play an important role, being one of the rate-controlling factors. But the energy levels associated with heat and mass transfer are of the orders much less than those of chemical reaction, and it is not easy to understand the thermal problems on the molecular and atomic basis. This paper views the processes of heat and mass transfer from the dynamical motions of atom and molecule for thermal engineering problems. Especially, problems are considered of heat conduction in fine-ceramics, sintered materials of high heat conductivity or high heat-insulation, phase change of condensation in vapor deposition processes such as CVD and PVD, and radiation in laser processing
Mass transfer in liquid phase catalytic exchange column of trickle bed type
International Nuclear Information System (INIS)
Yamanishi, Toshihiko; Iwai, Yasunori; Okuno, Kenji
1995-09-01
The mechanism of mass transfer in a liquid phase catalytic exchange column was discussed for a trickle bed type. A new model has been proposed on the basis of this mass transfer mechanism; and several problems for the previous reported models were pointed out in the derivation of the model. An overall rate equation was first derived from the vapor-hydrogen exchange in the model. The mass transfer for the vapor-hydrogen exchange was decomposed to the following three steps: the mass transfer in a gas boundary layer on a catalyst particle; the mass transfer within the pores in the catalyst; and the chemical reaction on the surface of the catalyst. The water-vapor scrubbing process was considered as a series of the mass transfers in gas and liquid boundary layers on the wetted surfaces of the catalyst and packings or wall of the column. Significant subjects to be studied were proposed from the viewpoint of the validity of the model and the optimization of the column. (author)
Heterogeneous studies in pulping of wood: Modelling mass transfer of alkali
Simão, João P. F.; Egas, Ana P. V.; Carvalho, M. Graça; Baptista, Cristina M. S. G.; Castro, José Almiro A. M.
2008-01-01
In this paper a heterogeneous lumped parameter model is proposed to describe the mass transfer of effective alkali during the kraft pulping of wood. This model, based on the spatial mean of the concentration profile of effective alkali along the chip thickness, enables the estimation of the effective diffusion coefficient that characterizes the internal resistance to mass transfer and the contribution of the external resistance to mass transfer which has often been neglected. http://www.sc...
Study of molecular iodine-epoxy paint mass transfer
Energy Technology Data Exchange (ETDEWEB)
Belval-Haltier, E [Inst. de Protection et Surete Nucleaire, IPSN, CEN Cadarache, St. Paul-lez-Durance (France)
1996-12-01
The mass transfer phenomena may have a significant influence on the quantity of I{sub 2} which could be released following a severe accident of a nuclear power plant and specially the mass transfer of iodine onto containment surfaces. So, the objective of the present work was to evaluate which phase limited the adsorption process of iodine onto gaseous epoxy paint under a range of conditions which may be relevant to a severe reactor accident. In this aim, a series of experiments was conducted in which the sorption kinetics of molecular iodine, labelled with {sup 131}I, was measured by monitoring continuously the accumulation of this species on the epoxy surface. For each test condition, the initial deposition velocity was determined and the corresponding gas phase mass transfer, kg, was estimated by using the heat transfer analogy for a laminar flow passing over a flat plate. Then, the surface reaction rate, Kr, was deduced from these two values. Experiments performed indicated that iodine adsorption onto epoxy paint is highly dependent on temperature, relative humidity of the carrier gas and moisture content of the painted coupon. In dry air flow conditions, the adsorption of iodine onto paint was found to increase with temperature and to be limited by the surface reaction rate, Kr. The I{sub 2} adsorption rate was found to increase with the humidity of carrier gas and in some studied conditions, the initial deposition velocity appeared to be controlled by gas phase mass transfer rather than surface interaction. The same phenomenon has been observed with an increase of the initial water content of the painted coupon. (author) 6 figs., 1 tab., 8 refs.
Mass transfer resistance in ASFF reactors for waste water treatment.
Ettouney, H M; Al-Haddad, A A; Abu-Irhayem, T M
1996-01-01
Analysis of mass transfer resistances was performed for an aerated submerged fixed-film reactor (ASFF) for the treatment of waste water containing a mixture of sucrose and ammonia. Both external and internal mass transfer resistances were considered in the analysis, and characterized as a function of feed flow-rate and concentration. Results show that, over a certain operating regime, external mass transfer resistance in the system was greater for sucrose removal than ammonia. This is because the reaction rates for carbon removal were much larger than those of nitrogen. As a result, existence of any form of mass transfer resistance caused by inadequate mixing or diffusion limitations, strongly affects the overall removal rates of carbon more than nitrogen. Effects of the internal måss transfer resistance were virtually non-existent for ammonia removal. This behaviour was found over two orders of magnitude range for the effective diffusivity for ammonia, and one order of magnitude for the film specific surface area. However, over the same parameters' range, it is found that sucrose removal was strongly affected upon lowering its effective diffusivity and increasing the film specific surface area.
The minimization of the extraneous electromagnetic fields of an inductive power transfer system
International Nuclear Information System (INIS)
McLean, James; Sutton, Robert
2013-01-01
The efficiency of inductive wireless power transfer (IPT) systems has been extensively studied. However, the electromagnetic compatibility of such systems is at least as important as the efficiency and has received much less attention. We consider the net magnetic dipole moment of the system as a figure of merit. That is, we seek to minimize the magnitude of the net dipole moment in order to minimize both the near magnetic fields and the radiated power. A 20 kHz, 3.3 kW, IPT system, representative of typical wireless vehicular battery charging systems, is considered and it is seen that one particular value of load impedance minimizes the net dipole moment while another, distinct, value maximizes efficiency. Thus, efficiency must be traded off, at least to some extent, in order to minimize extraneous electromagnetic fields.
Mass transfer in electromembrane extraction - The link between theory and experiments
DEFF Research Database (Denmark)
Huang, Chuixiu; Jensen, Henrik; Seip, Knut Fredrik
2016-01-01
typically been combined with chromatography, mass spectrometry, and electrophoresis for analyte separation and detection. At the moment, close to 125 research papers have been published with focus on electromembrane extraction. Electromembrane extraction is a hybrid technique between electrophoresis....... This review summarizes recent efforts to describe the fundamentals of mass transfer in electromembrane extraction, and aim to give an up-to-date understanding of the processes involved....... and liquid–liquid extraction, and the fundamental principles for mass transfer have only partly been investigated. Thus, although there is great interest in electromembrane extraction, the fundamental principle for mass transfer has to be described in more detail for the scientific acceptance of the concept...
Mass Transfer Limited Enhanced Bioremediation at Dnapl Source Zones: a Numerical Study
Kokkinaki, A.; Sleep, B. E.
2011-12-01
The success of enhanced bioremediation of dense non-aqueous phase liquids (DNAPLs) relies on accelerating contaminant mass transfer from the organic to the aqueous phase, thus enhancing the depletion of DNAPL source zones compared to natural dissolution. This is achieved by promoting biological activity that reduces the contaminant's aqueous phase concentration. Although laboratory studies have demonstrated that high reaction rates are attainable by specialized microbial cultures in DNAPL source zones, field applications of the technology report lower reaction rates and prolonged remediation times. One possible explanation for this phenomenon is that the reaction rates are limited by the rate at which the contaminant partitions from the DNAPL to the aqueous phase. In such cases, slow mass transfer to the aqueous phase reduces the bioavailability of the contaminant and consequently decreases the potential source zone depletion enhancement. In this work, the effect of rate limited mass transfer on bio-enhanced dissolution of DNAPL chlorinated ethenes is investigated through a numerical study. A multi-phase, multi-component groundwater transport model is employed to simulate DNAPL mass depletion for a range of source zone scenarios. Rate limited mass transfer is modeled by a linear driving force model, employing a thermodynamic approach for the calculation of the DNAPL - water interfacial area. Metabolic reductive dechlorination is modeled by Monod kinetics, considering microbial growth and self-inhibition. The model was utilized to identify conditions in which mass transfer, rather than reaction, is the limiting process, as indicated by the bioavailability number. In such cases, reaction is slower than expected, and further increase in the reaction rate does not enhance mass depletion. Mass transfer rate limitations were shown to affect both dechlorination and microbial growth kinetics. The complex dynamics between mass transfer, DNAPL transport and distribution, and
Effect of Orifice Nozzle Design and Input Power on Two-Phase Flow and Mass Transfer Characteristics
Energy Technology Data Exchange (ETDEWEB)
Yang, Hei Cheon [Chonnam Nat’l Univ., Gwangju (Korea, Republic of)
2016-04-15
It is necessary to investigate the input power as well as the mass transfer characteristics of the aeration process in order to improve the energy efficiency of an aerobic water treatment. The objective of this study is to experimentally investigate the effect of orifice nozzle design and input power on the flow and mass transfer characteristics of a vertical two-phase flow. The mass ratio, input power, volumetric mass transfer coefficient, and mass transfer efficiency were calculated using the measured data. It was found that as the input power increases the volumetric mass transfer coefficient increases, while the mass ratio and mass transfer efficiency decrease. The mass ratio, volumetric mass transfer coefficient, and mass transfer efficiency were higher for the orifice configuration with a smaller orifice nozzle area ratio. An empirical correlation was proposed to estimate the effect of mass ratio, input power, and Froude number on the volumetric mass transfer coefficient.
Transport Visualization for Studying Mass Transfer and Solute Transport in Permeable Media
International Nuclear Information System (INIS)
Roy Haggerty
2004-01-01
Understanding and predicting mass transfer coupled with solute transport in permeable media is central to several energy-related programs at the US Department of Energy (e.g., CO 2 sequestration, nuclear waste disposal, hydrocarbon extraction, and groundwater remediation). Mass transfer is the set of processes that control movement of a chemical between mobile (advection-dominated) domains and immobile (diffusion- or sorption-dominated) domains within a permeable medium. Consequences of mass transfer on solute transport are numerous and may include (1) increased sequestration time within geologic formations; (2) reduction in average solute transport velocity by as much as several orders of magnitude; (3) long ''tails'' in concentration histories during removal of a solute from a permeable medium; (4) poor predictions of solute behavior over long time scales; and (5) changes in reaction rates due to mass transfer influences on pore-scale mixing of solutes. Our work produced four principle contributions: (1) the first comprehensive visualization of solute transport and mass transfer in heterogeneous porous media; (2) the beginnings of a theoretical framework that encompasses both macrodispersion and mass transfer within a single set of equations; (3) experimental and analytical tools necessary for understanding mixing and aqueous reaction in heterogeneous, granular porous media; (4) a clear experimental demonstration that reactive transport is often not accurately described by a simple coupling of the convection-dispersion equation with chemical reaction equations. The work shows that solute transport in heterogeneous media can be divided into 3 regimes--macrodispersion, advective mass transfer, and diffusive mass transfer--and that these regimes can be predicted quantitatively in binary media. We successfully predicted mass transfer in each of these regimes and verified the prediction by completing quantitative visualization experiments in each of the regimes, the
Mass transfer intensification of nanofluid single drops with effect of temperature
Energy Technology Data Exchange (ETDEWEB)
Saien, Javad; Zardoshti, Mahdi [Bu-Ali Sina University, Hamedan (Iran, Islamic Republic of)
2015-11-15
The hydrodynamics and mass transfer of organic nanofluid single drops in liquid-liquid extraction process were investigated within temperature range of 20 to 40 .deg. C. Nanofluid drops of toluene+acetic acid, containing surface modified magnetite nanoparticles (NPs) with concentration within the range of (0.0005-0.005) wt%, were conducted in aqueous continuous phase. The rate of solute mass transfer was generally enhanced with NPs until about 0.002wt%, and small drops benefited more. The enhancement reached 184.1% with 0.002 wt% of NPs at 40 .deg. C; however, adding more NPs led to the mass transfer to either remain constant or face a reduction, depending on the applied temperature. The mass transfer coefficient was nicely reproduced using a developed correlation for enhancement factor of molecular diffusivity as a function of Reynolds and Schmidt numbers.
Energy Technology Data Exchange (ETDEWEB)
Gurler, O. [Physics Department, Faculty of Arts and Sciences, Uludag University, Gorukle Campus, 16059 Bursa (Turkey)], E-mail: ogurler@uludag.edu.tr; Oz, H. [Physics Department, Faculty of Arts and Sciences, Uludag University, Gorukle Campus, 16059 Bursa (Turkey); Yalcin, S. [Education Faculty, Kastamonu University, 37200 Kastamonu (Turkey); Gundogdu, O. [Department of Physics, University of Surrey, Guildford GU2 7XH (United Kingdom); NCCPM, Medical Physics, Royal Surrey County Hospital, GU2 7XX (United Kingdom)
2009-01-15
The mass energy absorption, the mass energy transfer and mass absorption coefficients have been widely used for problems and applications involving dose calculations. Direct measurements of the coefficients are difficult, and theoretical computations are usually employed. In this paper, analytical equations are presented for determining the mass energy transfer and mass absorption coefficients for gamma rays with an incident energy range between 0.4 and 10 MeV in nitrogen, silicon, carbon, copper and sodium iodide. The mass absorption and mass energy transfer coefficients for gamma rays were calculated, and the results obtained were compared with the values reported in the literature.
International Nuclear Information System (INIS)
Gurler, O.; Oz, H.; Yalcin, S.; Gundogdu, O.
2009-01-01
The mass energy absorption, the mass energy transfer and mass absorption coefficients have been widely used for problems and applications involving dose calculations. Direct measurements of the coefficients are difficult, and theoretical computations are usually employed. In this paper, analytical equations are presented for determining the mass energy transfer and mass absorption coefficients for gamma rays with an incident energy range between 0.4 and 10 MeV in nitrogen, silicon, carbon, copper and sodium iodide. The mass absorption and mass energy transfer coefficients for gamma rays were calculated, and the results obtained were compared with the values reported in the literature
The transfer of alkanoic acids from dodecane to water
International Nuclear Information System (INIS)
Sagert, N.H.; Quinn, M.J.; Dixon, R.S.
1981-01-01
A rotating diffusion cell was used to study the transfer of five alkanoic acids from dodecane to water under conditions of known interfacial area and hydrodynamics. hd The acids studied were acetic, butanoic, hexanoic, 2-methylbutanoic and 2,2-dimethylpropanoic acids. Small interfacial resistances to mass transfer were noted, the mass transfer coefficients for interfacial transfer being in the range 2.6 to 4.7 μm/s at 25 0 C. This small range means that the effects of the length and structure of the alkane chain on the resistance to mass transfer are minimal. A study of the temperature dependence of the resistance to mass transfer at the interface showed that the resistance is largely entropic rather than enthalpic. (author)
Mass-transfer studies in an electrochemical reactor with a small interelectrode gap
International Nuclear Information System (INIS)
Colli, A.N.; Toelzer, R.; Bergmann, M.E.H.; Bisang, J.M.
2013-01-01
Highlights: • Turbulence promoters increase from two to eight times the mass-transfer coefficients. • Turbulence promoters become more uniform the mass-transfer distribution. • Expanded plastics with an open structure are appropriate as turbulence promoters. -- Abstract: This paper reports the distribution of the local mass-transfer coefficient along the electrode length for an electrochemical reactor with parallel-plate electrodes and narrow interelectrode gaps of 1 and 2.2 mm, using the reduction of ferricyanide as a test reaction. The studies were performed at different flow rates, Reynolds numbers ranging from 370 to 3700, with the empty reactor and also the interelectrode gap was filled with two types of expanded plastics and a woven plastic mesh as turbulence promoters. The effect of both the interelectrode gap and the partial placing of the turbulence promoter along the electrode length on the mass-transfer behaviour was also analyzed. In all cases the pressure drop across the reactor was measured. A more uniform distribution of the local mass-transfer coefficient, ±15% related to its mean value, and an important increase of the mean mass-transfer coefficient, enhancement factor ranging from 2 to 8, were observed, depending on the type of turbulence promoter, the volumetric flow rate, and the interelectrode gap
Radiation-induced Mass Transfer through Membranes
Czech Academy of Sciences Publication Activity Database
Levdansky, V.V.; Smolík, Jiří; Moravec, Pavel
2009-01-01
Roč. 36, č. 2 (2009), s. 125-128 ISSN 0735-1933 R&D Projects: GA AV ČR(CZ) IAA400720804 Institutional research plan: CEZ:AV0Z40720504 Keywords : mass transfer * adiation * membrane Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.189, year: 2009
Gravity-assisted exact unification in minimal supersymmetric SU(5) and its gaugino mass spectrum
International Nuclear Information System (INIS)
Tobe, Kazuhiro; Wells, James D.
2004-01-01
Minimal supersymmetric SU(5) with exact unification is naively inconsistent with proton decay constraints. However, it can be made viable by a gravity-induced non-renormalizable operator connecting the adjoint Higgs boson and adjoint vector boson representations. We compute the allowed coupling space for this theory and find natural compatibility with proton decay constraints even for relatively light superpartner masses. The modifications away from the naive SU(5) theory have an impact on the gaugino mass spectrum, which we calculate. A combination of precision linear collider and large hadron collider measurements of superpartner masses would enable interesting tests of the high-scale form of minimal supersymmetric SU(5)
Effect of rotation on convective mass transfer in rotating channels
International Nuclear Information System (INIS)
Pharoah, J.G.; Djilali, N.
2002-01-01
Laminar flow and mass transfer in rotating channels is investigated in the context of centrifugal membrane separation. The effect of orientation with respect to the rotational axis is examined for rectangular channels of aspect ratio 3 and the Rossby number is varied from 0.3 to 20.9. Both Ro and the channel orientation are found to have a significant effect on the flow. Mass transfer calculations corresponding to reverse osmosis desalination are carried out at various operating pressures and all rotating cases exhibit significant process enhancements at relatively low rotation rates. Finally, while it is common in the membrane literature to correlate mass transfer performance with membrane shear rates this is shown not to be valid in the cases presented herein. (author)
Heat transfer from a tube bank with mass transfer in a duct
International Nuclear Information System (INIS)
Nouri, A.; Lavasani, A. M.
2005-01-01
An experimental investigation on heat transfer coefficient is present from three horizontal tubes in a vertical array in a duct for 500 D <6000. A mass transfer measuring technique based on psychrometry chart is used to determine heat transfer coefficient. The diameter of the tubes is 11 mm each spaced 40 mm apart and in-line pitch ratio varies in the range 0.055< D/W<0.22. The experimental results show that the Nusselt number of each tube increases by increasing D/W. Also the increase of the second the Nusselt number is more than that of the third one
Simultaneous heat and mass transfer on oscillatory free convection boundary layer flow
International Nuclear Information System (INIS)
Hossain, M.A.
1985-11-01
The problem of simultaneous heat and mass transfer in two-dimensional free convection from a semi-infinite vertical flat plate is investigated. An integral method is used to find a solution for zero wall velocity and for a mass transfer velocity at the wall with small-amplitude oscillatory wall temperature. Low and high-frequency solutions are developed separately and are discussed graphically with the effects of the parameters Gr (the Grashof number for heat transfer), Gc (the Grashof number for mass transfer) and Sc (the Schmidt number) for Pr=0.71 representing aid at 20 deg. C. (author)
Modelling of heat and mass transfer processes in neonatology
Energy Technology Data Exchange (ETDEWEB)
Ginalski, Maciej K [FLUENT Europe, Sheffield Business Park, Europa Link, Sheffield S9 1XU (United Kingdom); Nowak, Andrzej J [Institute of Thermal Technology, Silesian University of Technology, Konarskiego 22, 44-100 Gliwice (Poland); Wrobel, Luiz C [School of Engineering and Design, Brunel University, Uxbridge UB8 3PH (United Kingdom)], E-mail: maciej.ginalski@ansys.com, E-mail: Andrzej.J.Nowak@polsl.pl, E-mail: luiz.wrobel@brunel.ac.uk
2008-09-01
This paper reviews some of our recent applications of computational fluid dynamics (CFD) to model heat and mass transfer problems in neonatology and investigates the major heat and mass transfer mechanisms taking place in medical devices such as incubators and oxygen hoods. This includes novel mathematical developments giving rise to a supplementary model, entitled infant heat balance module, which has been fully integrated with the CFD solver and its graphical interface. The numerical simulations are validated through comparison tests with experimental results from the medical literature. It is shown that CFD simulations are very flexible tools that can take into account all modes of heat transfer in assisting neonatal care and the improved design of medical devices.
Modelling of heat and mass transfer processes in neonatology
International Nuclear Information System (INIS)
Ginalski, Maciej K; Nowak, Andrzej J; Wrobel, Luiz C
2008-01-01
This paper reviews some of our recent applications of computational fluid dynamics (CFD) to model heat and mass transfer problems in neonatology and investigates the major heat and mass transfer mechanisms taking place in medical devices such as incubators and oxygen hoods. This includes novel mathematical developments giving rise to a supplementary model, entitled infant heat balance module, which has been fully integrated with the CFD solver and its graphical interface. The numerical simulations are validated through comparison tests with experimental results from the medical literature. It is shown that CFD simulations are very flexible tools that can take into account all modes of heat transfer in assisting neonatal care and the improved design of medical devices
Mass transfer with complex reversible chemical reactions—II. parallel reversible chemical reactions
Versteeg, G.F.; Kuipers, J.A.M.; Beckum, F.P.H. van; Swaaij, W.P.M. van
1990-01-01
An absorption model has been developed which can be used to calculate rapidly absorption rates for the phenomenon mass transfer accompanied by multiple complex parallel reversible chemical reactions. This model can be applied for the calculation of the mass transfer rates, enhancement factors and concentration profiles for a wide range of processes and conditions, for both film and penetration model. With the aid of this mass transfer model it is demonstrated that the absorption rates in syst...
Mass and charge transfer within a floating water bridge
Fuchs, Elmar C.; Agostinho, Luewton L. F.; Eisenhut, Mathias; Woisetschläger, Jakob
2010-11-01
When high voltage is applied to pure water filled into two beakers close to each other, a connection forms spontaneously, giving the impression of a floating water bridge 1-8. This phenomenon is of special interest, since it comprises a number of phenomena currently tackled in modern water science. In this work, the charge and mass transfer through the water bridge are investigated with schlieren visualization and laser interferometry. It can be shown that the addition of a pH dye increases the H+ and OH- production with subsequent electrolysis, whereas schlieren and interferometric methods reveal another mechanism where charge and mass transfer appear to be coupled. Whereas this mechanism seems to be responsible for the electrolysis-less charge and mass transfer in the water bridge, it is increasingly superseded by the electrochemical mechanism with rising conductivity. Thus it can be shown that a pH dye does only indirectly visualize the charge transfer in the water bridge since it is dragged along with the water flow like any other dye, and additionally promotes conventional electrochemical conduction mechanisms, thereby enhancing electrolysis and reducing the masscoupled charge transport and thus destabilizing the bridge.
Mass transfer models analysis for the structured packings
International Nuclear Information System (INIS)
Suastegui R, A.O.
1997-01-01
The models that have been developing, to understand the mechanism of the mass transfer through the structured packings, present limitations for their application, existing then uncertainty in order to use them in the chemical industrial processes. In this study the main parameters used in the mass transfer are: the hydrodynamic of the bed of the column, the geometry of the bed, physical-chemical properties of the mixture and the flow regime of the operation between the flows liquid-gas. The sensibility of each one of these parameters generate an arduous work to develop right proposals and good interpretation of the phenomenon. With the purpose of showing the importance of these parameters mentioned in the mass transfer, this work is analyzed the process of absorption for the system water-air, using the models to the structured packings in packed columns. The models selected were developed by Bravo and collaborators in 1985 and 1992, in order to determine the parameters previous mentioned for the system water-air, using a structured packing built in the National Institute of Nuclear Research. In this work is showed the results of the models application and their discussion. (Author)
Solid lubricant mass contact transfer technology usage for vacuum ball bearings longevity increasing
Arzymatov, B.; Deulin, E.
2016-07-01
A contact mass transfer technological method of solid lubricant deposition on components of vacuum ball bearings is presented. Physics-mathematical model of process contact mass transfer is being considered. The experimental results of ball bearings covered with solid lubricant longevity in vacuum are presented. It is shown that solid lubricant of contact mass transfer method deposition is prospective for ball bearing longevity increasing.
Heat and mass transfer in building services design
Moss, Keith
1998-01-01
Building design is increasingly geared towards low energy consumption. Understanding the fundamentals of heat transfer and the behaviour of air and water movements is more important than ever before. Heat and Mass Transfer in Building Services Design provides an essential underpinning knowledge for the technology subjects of space heating, water services, ventilation and air conditioning. This new text: *provides core understanding of heat transfer and fluid flow from a building services perspective *complements a range of courses in building services engineering *
Mixing and mass transfer in a pilot scale U-loop bioreactor
DEFF Research Database (Denmark)
Petersen, Leander Adrian Haaning; Villadsen, John; Jørgensen, Sten Bay
2017-01-01
A system capable of handling a large volumetric gas fraction while providing a high gas to liquid mass transfer is a necessity if the metanotrophic bacterium Methylococcus capsulatus is to be used in single cell protein (SCP) production. In this study mixing time and mass transfer coefficients we...
Introduction to computational mass transfer with applications to chemical engineering
Yu, Kuo-Tsong
2014-01-01
This book presents a new computational methodology called Computational Mass Transfer (CMT). It offers an approach to rigorously simulating the mass, heat and momentum transfer under turbulent flow conditions with the help of two newly published models, namely the C’2—εC’ model and the Reynolds mass flux model, especially with regard to predictions of concentration, temperature and velocity distributions in chemical and related processes. The book will also allow readers to understand the interfacial phenomena accompanying the mass transfer process and methods for modeling the interfacial effect, such as the influences of Marangoni convection and Rayleigh convection. The CMT methodology is demonstrated by means of its applications to typical separation and chemical reaction processes and equipment, including distillation, absorption, adsorption and chemical reactors. Professor Kuo-Tsong Yu is a Member of the Chinese Academy of Sciences. Dr. Xigang Yuan is a Professor at the School of Chemical Engine...
Simultaneous Heat and Mass Transfer Model for Convective Drying of Building Material
Upadhyay, Ashwani; Chandramohan, V. P.
2018-04-01
A mathematical model of simultaneous heat and moisture transfer is developed for convective drying of building material. A rectangular brick is considered for sample object. Finite-difference method with semi-implicit scheme is used for solving the transient governing heat and mass transfer equation. Convective boundary condition is used, as the product is exposed in hot air. The heat and mass transfer equations are coupled through diffusion coefficient which is assumed as the function of temperature of the product. Set of algebraic equations are generated through space and time discretization. The discretized algebraic equations are solved by Gauss-Siedel method via iteration. Grid and time independent studies are performed for finding the optimum number of nodal points and time steps respectively. A MATLAB computer code is developed to solve the heat and mass transfer equations simultaneously. Transient heat and mass transfer simulations are performed to find the temperature and moisture distribution inside the brick.
Influence of drying air parameters on mass transfer characteristics of apple slices
Beigi, Mohsen
2016-10-01
To efficiently design both new drying process and equipment and/or to improve the existing systems, accurate values of mass transfer characteristics are necessary. The present study aimed to investigate the influence of drying air parameters (i.e. temperature, velocity and relative humidity) on effective diffusivity and convective mass transfer coefficient of apple slices. The Dincer and Dost model was used to determine the mass transfer characteristics. The obtained Biot number indicated that the moisture transfer in the apple slices was controlled by both internal and external resistance. The effective diffusivity and mass transfer coefficient values obtained to be in the ranges of 7.13 × 10-11-7.66 × 10-10 and 1.46 × 10-7-3.39 × 10-7 m s-1, respectively and the both of them increased with increasing drying air temperature and velocity, and decreasing relative humidity. The validation of the model showed that the model predicted the experimental drying curves of the samples with a good accuracy.
Deviations from mass transfer equilibrium and mathematical modeling of mixer-settler contactors
International Nuclear Information System (INIS)
Beyerlein, A.L.; Geldard, J.F.; Chung, H.F.; Bennett, J.E.
1980-01-01
This paper presents the mathematical basis for the computer model PUBG of mixer-settler contactors which accounts for deviations from mass transfer equilibrium. This is accomplished by formulating the mass balance equations for the mixers such that the mass transfer rate of nuclear materials between the aqueous and organic phases is accounted for. 19 refs
The minimally tuned minimal supersymmetric standard model
International Nuclear Information System (INIS)
Essig, Rouven; Fortin, Jean-Francois
2008-01-01
The regions in the Minimal Supersymmetric Standard Model with the minimal amount of fine-tuning of electroweak symmetry breaking are presented for general messenger scale. No a priori relations among the soft supersymmetry breaking parameters are assumed and fine-tuning is minimized with respect to all the important parameters which affect electroweak symmetry breaking. The superpartner spectra in the minimally tuned region of parameter space are quite distinctive with large stop mixing at the low scale and negative squark soft masses at the high scale. The minimal amount of tuning increases enormously for a Higgs mass beyond roughly 120 GeV
Influence of the boundary conditions on heat and mass transfer in spacer-filled channels
Ciofalo, M.; La Cerva, M. F.; Di Liberto, M.; Tamburini, A.
2017-11-01
The purpose of this study is to discuss some problems which arise in heat or mass transfer in complex channels, with special reference to the spacer-filled channels adopted in membrane processes. Among the issues addressed are the consistent definition of local and mean heat or mass transfer coefficients; the influence of the wall boundary conditions; the influence of one-side versus two-side heat/mass transfer. Most of the results discussed were obtained by finite volume CFD simulations concerning heat transfer in Membrane Distillation or mass transfer in Electrodialysis and Reverse Electrodialysis, but many of the conclusions apply also to different processes involving geometrically complex channels
International Nuclear Information System (INIS)
Kritsuk, E.L.; Mishina, L.V.; Shegidevich, L.N.
1986-01-01
The hydrodynamically stabilized chemically nonequilibrium turbulent flow in a tube with the inert impermeable surface and constant specific heat flow on the wall is considered. The reversible homogeneous reaction of nitrogen dioxide dissociation 2NO 2 ↔ 2NO+O 2 takes place in the flow. Chemically equilibrium flow with homogeneous profile of temperature and concentration arrives into the channel inlet. After application of simplifying assumptions, the expressions for characteristics of heat and mass transfer have been written down, which are valid in the whole range of the flow parameter variation from frozen up to chemically equilibrium flow. An integral transformation method is suggested for a radial coordinate which allows a wall region to be extended, thereby essentially extending the step of integration. A solution in quadratures has been obtained for the heat and mass transfer problem in an inert fluid flow for the developed process section. The elimination method has been employed to solve the boundary-value second-kind problem for the function governing heat and mass transfer in a chemically nonequilibrium turbulent flow over the developed heat and mass transfer section. The results of calculations are presented
Mass transfer apparatus and method for separation of gases
Energy Technology Data Exchange (ETDEWEB)
Blount, Gerald C.; Gorensek, Maximilian Boris; Hamm, Luther L.
2018-01-16
A process and apparatus for separating components of a source gas is provided in which more soluble components of the source gas are dissolved in an aqueous solvent at high pressure. The system can utilize hydrostatic pressure to increase solubility of the components of the source gas. The apparatus includes gas recycle throughout multiple mass transfer stages to improve mass transfer of the targeted components from the liquid to gas phase. Separated components can be recovered for use in a value added application or can be processed for long-term storage, for instance in an underwater reservoir.
Mass transfer with complex reversible chemical reactions—II. parallel reversible chemical reactions
Versteeg, G.F.; Kuipers, J.A.M.; Beckum, F.P.H. van; Swaaij, W.P.M. van
1990-01-01
An absorption model has been developed which can be used to calculate rapidly absorption rates for the phenomenon mass transfer accompanied by multiple complex parallel reversible chemical reactions. This model can be applied for the calculation of the mass transfer rates, enhancement factors and
Mass transfer with complex reversible chemical reactions. II: Parallel reversible chemical reactions
Versteeg, Geert; van Beckum, F.P.H.; Kuipers, J.A.M.; van Swaaij, Willibrordus Petrus Maria
1990-01-01
An absorption model has been developed which can be used to calculate rapidly absorption rates for the phenomenon mass transfer accompanied by multiple complex parallel reversible chemical reactions. This model can be applied for the calculation of the mass transfer rates, enhancement factors and
Mass transfer with complex reversible chemical reactions. II: parallel reversible chemical reactions
Versteeg, G.F.; Kuipers, J.A.M.; Beckum, van F.P.H.; van Swaaij, W.P.M.
1990-01-01
An absorption model has been developed which can be used to calculate rapidly absorption rates for the phenomenon mass transfer accompanied by multiple complex parallel reversible chemical reactions. This model can be applied for the calculation of the mass transfer rates, enhancement factors and
Permanently reconfigured metamaterials due to terahertz induced mass transfer of gold
DEFF Research Database (Denmark)
Strikwerda, Andrew; Zalkovskij, Maksim; Iwaszczuk, Krzysztof
2015-01-01
We present a new technique for permanent metamaterial reconfiguration via optically induced mass transfer of gold. This mass transfer, which can be explained by field-emission induced electromigration, causes a geometric change in the metamaterial sample. Since a metamaterial's electromagnetic...... response is dictated by its geometry, this structural change massively alters the metamaterial's behavior. We show this by optically forming a conducting pathway between two closely spaced dipole antennas, thereby changing the resonance frequency by a factor of two. After discussing the physics...... of the process, we conclude by presenting an optical fuse that can be used as a sacrificial element to protect sensitive components, demonstrating the applicability of optically induced mass transfer for device design. (C)2015 Optical Society of America...
Characteristics of Gas-liquid Mass Transfer and Interfacial Area in a Bubble Column
International Nuclear Information System (INIS)
Lim, Dae Ho; Yoo, Dong Jun; Kang, Yong
2015-01-01
Characteristics of gas-liquid mass transfer and interfacial area were investigated in a bubble column of diameter and height of 0.102 m and 2.5 m, respectively. Effects of gas and liquid velocities on the volumetric gas-liquid mass transfer coefficient (k L a), interfacial area (a) and liquid side true mass transfer coefficient (k L ) were examined. The interfacial area and volumetric gas-liquid mass transfer coefficient were determined directly by adopting the simultaneous physical desorption of O 2 and chemical absorption of CO 2 in the column. The values of k L a and a increased with increasing gas velocity but decreased with increasing liquid velocity in the bubble column which was operated in the churn turbulent flow regime. The value of k L increased with increasing gas velocity but did not change considerably with increasing liquid velocity. The liquid side mass transfer was found to be related closely to the liquid circulation as well as the effective contacting frequency between the bubbles and liquid phases
Characteristics of Gas-liquid Mass Transfer and Interfacial Area in a Bubble Column
Energy Technology Data Exchange (ETDEWEB)
Lim, Dae Ho; Yoo, Dong Jun; Kang, Yong [Chungnam National University, Daejeon (Korea, Republic of)
2015-02-15
Characteristics of gas-liquid mass transfer and interfacial area were investigated in a bubble column of diameter and height of 0.102 m and 2.5 m, respectively. Effects of gas and liquid velocities on the volumetric gas-liquid mass transfer coefficient (k{sub L}a), interfacial area (a) and liquid side true mass transfer coefficient (k{sub L}) were examined. The interfacial area and volumetric gas-liquid mass transfer coefficient were determined directly by adopting the simultaneous physical desorption of O{sub 2} and chemical absorption of CO{sub 2} in the column. The values of k{sub L}a and a increased with increasing gas velocity but decreased with increasing liquid velocity in the bubble column which was operated in the churn turbulent flow regime. The value of k{sub L} increased with increasing gas velocity but did not change considerably with increasing liquid velocity. The liquid side mass transfer was found to be related closely to the liquid circulation as well as the effective contacting frequency between the bubbles and liquid phases.
Mass transfer from smooth alabaster surfaces in turbulent flows
Opdyke, Bradley N.; Gust, Giselher; Ledwell, James R.
1987-11-01
The mass transfer velocity for alabaster plates in smooth-wall turbulent flow is found to vary with the friction velocity according to an analytic solution of the advective diffusion equation. Deployment of alabaster plates on the sea floor can perhaps be used to estimate the viscous stress, and transfer velocities for other species.
Abstracts of international symposium on heat and mass transfer under plasma conditions
International Nuclear Information System (INIS)
1994-01-01
The international symposium on heat and mass transfer under plasma conditions was held on 4-8 July 1994 in Cesme, Izmir, Turkey. The spesialists discussed heat and mass transfer in the field of plasma processing at the meeting. More than 70 papers were presented in the meeting
Abstracts of international symposium on heat and mass transfer under plasma conditions
Energy Technology Data Exchange (ETDEWEB)
NONE
1994-12-31
The international symposium on heat and mass transfer under plasma conditions was held on 4-8 July 1994 in Cesme, Izmir, Turkey. The spesialists discussed heat and mass transfer in the field of plasma processing at the meeting. More than 70 papers were presented in the meeting.
Heat and mass transfer intensification and shape optimization a multi-scale approach
2013-01-01
Is the heat and mass transfer intensification defined as a new paradigm of process engineering, or is it just a common and old idea, renamed and given the current taste? Where might intensification occur? How to achieve intensification? How the shape optimization of thermal and fluidic devices leads to intensified heat and mass transfers? To answer these questions, Heat & Mass Transfer Intensification and Shape Optimization: A Multi-scale Approach clarifies the definition of the intensification by highlighting the potential role of the multi-scale structures, the specific interfacial area, the distribution of driving force, the modes of energy supply and the temporal aspects of processes. A reflection on the methods of process intensification or heat and mass transfer enhancement in multi-scale structures is provided, including porous media, heat exchangers, fluid distributors, mixers and reactors. A multi-scale approach to achieve intensification and shape optimization is developed and clearly expla...
Effect of aging on mass transfer naphthalene from creosotes to water
International Nuclear Information System (INIS)
Alshafie, M.; Ghoshal, S.
2002-01-01
Semi-gelatinous interfacial films or 'skins' have been observed to form at the interface of creosote and water when creosote is aged (contacted over an extended time period) in water under quiescent conditions for a few days. The objective of the research is to investigate whether aging of creosote-water interfaces and the formation of interfacial films retard dissolution of a target solute, naphthalene, from samples of creosote. Mass transfer experiments were conducted in gently stirred flow-through reactors where the NAPL was coated on glass beads so as to keep the NAPL and the aqueous phases segregated. The aqueous concentration in the reactor effluent was determined in samples collected at different time points and the equilibrium partitioning coefficients and area-independent mass transfer coefficients were calculated. Over the period of one week, the mass transfer rate coefficients of the naphthalene from creosote to water underwent approximately 30% reduction. Further reduction was observed up to 3 weeks of aging. This significant reduction in mass transfer coefficient has important implications on potential rates of dissolution of the solutes, and thus on rates of clean up of creosote-contaminated sites. (author)
Simulation of heat and mass transfer in boiling water with the Melodif code
International Nuclear Information System (INIS)
Freydier, P.; Chen, O.; Olive, J.; Simonin, O.
1991-04-01
The Melodif code is developed at Electricite de France, Research and Development Division. It is an eulerian two dimensional code for the simulation of turbulent two phase flows (a three dimensional code derived from Melodif, ASTRID, is currently being prepared). Melodif is based on the two fluid model, solving the equations of conservation for mass, momentum and energy, for both phases. In such a two fluid model, the description of interfacial transfers between phases is a crucial issue. The model used applies to a dominant continuous phase, and a dispersed phase. A good description of interfacial momentum transfer exists in the standard MELODIF code: the drag force, the apparent mass force... are taken into account. An important factor for interfacial transfers is the interfacial area per volume unit. With the assumption of spherical gas bubbles, an equation has been written for this variable. In the present wok, a model has been tested for interfacial heat and mass transfer in the case of boiling water: it is assumed that mass transfer is controlled by heat transfer through the latent massic energy taken in the phase that vaporizes (or condenses). This heat and mass transfer model has been tested in various configurations: - a cylinder with water flowing inside, is being heated. Boiling takes place near the wall, while bubbles migrating to the core of the flow recondense. This roughly simulates a sub-cooled boiling phenomenon. - a box containing liquid water is depressurized. Boiling takes place in the whole volume of the fluid. The Melodif code can simulate this configuration due to the implicitation of the relation between interphase mass transfer and the pressure variable
Zhang, Yong; Li, Kuiling; Wang, Jun; Hou, Deyin; Liu, Huijuan
2017-09-01
To understand the mass transfer behaviors in hollow fiber membrane contactors, ozone fluxes affected by various conditions and membranes were investigated. For physical absorption, mass transfer rate increased with liquid velocity and the ozone concentration in the gas. Gas flow rate was little affected when the velocity was larger than the critical value, which was 6.1 × 10 -3 m/s in this study. For chemical absorption, the flux was determined by the reaction rate between ozone and the absorbent. Therefore, concentration, species, and pH affected the mass transfer process markedly. For different absorbents, the order of mass transfer rate was the same as the reaction rate constant, which was phenol, sodium nitrite, hydrogen peroxide, and oxalate. Five hydrophobic membranes with various properties were employed and the mass transfer behavior can be described by the Graetz-Lévèque equation for the physical absorption process. The results showed the process was controlled by liquid film and the gas phase conditions, and membrane properties did not affect the ozone flux. For the chemical absorption, gas film, membrane and liquid film affected the mass transfer together, and none of them were negligible.
CO2 Mass transfer model for carbonic anhydrase-enhanced aqueous MDEA solutions
DEFF Research Database (Denmark)
Gladis, Arne Berthold; Deslauriers, Maria Gundersen; Neerup, Randi
2018-01-01
In this study a CO2 mass transfer model was developed for carbonic anhydrase-enhanced MDEA solutions based on a mechanistic kinetic enzyme model. Four different enzyme models were compared in their ability to predict the liquid side mass transfer coefficient at temperatures in the range of 298...
Analysis of combined heat and mass transfer of water- Vapor in a ...
African Journals Online (AJOL)
In this paper, the combined heat and mass transfer of water-vapor into a cylindrical zeolite adsorber has been numerically simulated The twodimensional heat and mass transfer equations are numerically solved using gPROMS program - a general Process Modeling System {lJ program, inserting the proper initial and ...
Analysis of combined heat and mass transfer of water-vapor in a ...
African Journals Online (AJOL)
Jn this paper, the combined heat and mass transfer of water-vapor into a cylindrical zeolite adsorber has been numerically simulated The twodimensional heat and mass transfer equations are numerically solved using gPROMS program - a general Process Modeling System [J] program, inserting the proper initial and ...
Evaporative mass transfer behavior of a complex immiscible liquid.
McColl, Colleen M; Johnson, Gwynn R; Brusseau, Mark L
2008-09-01
A series of laboratory experiments was conducted with a multiple-component immiscible liquid, collected from the Picillo Farm Superfund Site in Rhode Island, to examine liquid-vapor mass-transfer behavior. The immiscible liquid, which comprises solvents, oils, pesticides, PCBs, paint sludges, explosives, and other compounds, was characterized using gas chromatography and gas chromatography/mass spectrometry to determine mole fractions of selected constituents. Batch experiments were conducted to evaluate equilibrium phase-partitioning behavior. Two sets of air-stripping column studies were conducted to examine the mass-transfer dynamics of five selected target compounds present in the immiscible-liquid mixture. One set of column experiments was designed to represent a system with free-phase immiscible liquid present; the other was designed to represent a system with a residual phase of immiscible liquid. Initial elution behavior of all target components generally appeared to be ideal for both systems, as the initial vapor-phase concentrations were similar to vapor-phase concentrations measured for the batch experiment and those estimated using Raoult's law (incorporating the immiscible-liquid composition data). Later-stage removal of 1,2-dichlorobenzene appeared to be rate limited for the columns containing free-phase immiscible liquid and no porous medium. Conversely, evaporative mass transfer appeared to be ideal throughout the experiment conducted with immiscible liquid distributed relatively uniformly as a residual phase within a sandy porous medium.
Molecular theory of mass transfer kinetics and dynamics at gas-water interface
International Nuclear Information System (INIS)
Morita, Akihiro; Garrett, Bruce C
2008-01-01
The mass transfer mechanism across gas-water interface is studied with molecular dynamics (MD) simulation. The MD results provide a robust and qualitatively consistent picture to previous studies about microscopic aspects of mass transfer, including interface structure, free energy profiles for the uptake, scattering dynamics and energy relaxation of impinging molecules. These MD results are quantitatively compared with experimental uptake measurements, and we find that the apparent inconsistency between MD and experiment could be partly resolved by precise decomposition of the observed kinetics into elemental steps. Remaining issues and future perspectives toward constructing a comprehensive multi-scale description of interfacial mass transfer are summarized.
Mass transfer Simulation of Two-dimensional Natural Convection of Mixture Layer in an IVR
Energy Technology Data Exchange (ETDEWEB)
Kim, Su-Hyeon; Chung, Bum-Jin [Kyung Hee University, Yongin (Korea, Republic of)
2015-10-15
This study is focusing on the angle dependent heat flux distribution at the reactor vessel plenum due to mixture layer natural convection experiment. We simulated heat transfer using a sulfuric acid - copper sulfate (H{sub 2}SO{sub 4} - CuSO{sub 4}) electroplating system based on the heat and mass transfer analogy concept. An S-bend shaped copper is used as the volumetric heat source, which is simulated as a heater in previous heat transfer studies. The advantage of mass transfer experiment is the achievement of the high buoyancy condition similar to reactor vessel because of high Pr. This study performed mass transfer experiment using a sulfuric acid - copper sulfate (H{sub 2}SO{sub 4} - CuSO{sub 4}) electroplating system based on the heat and mass transfer analogy concept. The experimental result was compared with previous 2D study (SIGMA CP)
Mass transfer model for two-layer TBP oxidation reactions
International Nuclear Information System (INIS)
Laurinat, J.E.
1994-01-01
To prove that two-layer, TBP-nitric acid mixtures can be safely stored in the canyon evaporators, it must be demonstrated that a runaway reaction between TBP and nitric acid will not occur. Previous bench-scale experiments showed that, at typical evaporator temperatures, this reaction is endothermic and therefore cannot run away, due to the loss of heat from evaporation of water in the organic layer. However, the reaction would be exothermic and could run away if the small amount of water in the organic layer evaporates before the nitric acid in this layer is consumed by the reaction. Provided that there is enough water in the aqueous layer, this would occur if the organic layer is sufficiently thick so that the rate of loss of water by evaporation exceeds the rate of replenishment due to mixing with the aqueous layer. This report presents measurements of mass transfer rates for the mixing of water and butanol in two-layer, TBP-aqueous mixtures, where the top layer is primarily TBP and the bottom layer is comprised of water or aqueous salt solution. Mass transfer coefficients are derived for use in the modeling of two-layer TBP-nitric acid oxidation experiments. Three cases were investigated: (1) transfer of water into the TBP layer with sparging of both the aqueous and TBP layers, (2) transfer of water into the TBP layer with sparging of just the TBP layer, and (3) transfer of butanol into the aqueous layer with sparging of both layers. The TBP layer was comprised of 99% pure TBP (spiked with butanol for the butanol transfer experiments), and the aqueous layer was comprised of either water or an aluminum nitrate solution. The liquid layers were air sparged to simulate the mixing due to the evolution of gases generated by oxidation reactions. A plastic tube and a glass frit sparger were used to provide different size bubbles. Rates of mass transfer were measured using infrared spectrophotometers provided by SRTC/Analytical Development
Prediction of transpiration effects on heat and mass transfer by different turbulence models
International Nuclear Information System (INIS)
Bucci, M.; Sharabi, M.; Ambrosini, W.; Forgione, N.; Oriolo, F.; He, S.
2008-01-01
The paper reports the results of a study related to transpirating flows, stimulated by the interest that these phenomena, occurring in the presence of simultaneous heat and mass transfer, have for nuclear reactor applications. The work includes a summary and the follow-up of previous experimental and numerical investigations on filmwise condensation and falling film evaporation and of a recent review of different forms of the heat and mass transfer analogy. The particular objective here pursued is to compare transpiration effects as predicted by different turbulence models with classical suction and blowing multipliers based on stagnant layer theories, in the attempt to clarify their quantitative implications on the predicted mass transfer rates. A commercial and an in-house CFD code have been adopted for evaluating the heat and mass transfer rates occurring over a flat plate exposed to an air-vapour stream, with uniform bulk steam mass fraction and temperature boundary conditions at the wall. This simple configuration was purposely selected since it is a simplified representation of the test section of an experimental facility presently in operation at the University of Pisa. This allows a direct comparison between the heat and mass transfer coefficients predicted by CFD models and classical correlations for Nusselt and Sherwood numbers
Fem Formulation for Heat and Mass Transfer in Porous Medium
Azeem; Soudagar, Manzoor Elahi M.; Salman Ahmed, N. J.; Anjum Badruddin, Irfan
2017-08-01
Heat and mass transfer in porous medium can be modelled using three partial differential equations namely, momentum equation, energy equation and mass diffusion. These three equations are coupled to each other by some common terms that turn the whole phenomenon into a complex problem with inter-dependable variables. The current article describes the finite element formulation of heat and mass transfer in porous medium with respect to Cartesian coordinates. The problem under study is formulated into algebraic form of equations by using Galerkin's method with the help of two-node linear triangular element having three nodes. The domain is meshed with smaller sized elements near the wall region and bigger size away from walls.
Fuzzy cluster quantitative computations of component mass transfer in rocks or minerals
International Nuclear Information System (INIS)
Liu Dezheng
2000-01-01
The author advances a new component mass transfer quantitative computation method on the basis of closure nature of mass percentage of components in rocks or minerals. Using fuzzy dynamic cluster analysis, and calculating restore closure difference, and determining type of difference, and assisted by relevant diagnostic parameters, the method gradually screens out the true constant component. Then, true mass percentage and mass transfer quantity of components of metabolic rocks or minerals are calculated by applying the true constant component fixed coefficient. This method is called true constant component fixed method (TCF method)
Energy Technology Data Exchange (ETDEWEB)
Koyama, Shigeru; Yu, Jian; Ishibashi, Akira
1999-07-01
In the face of the phase-out of HCFC22 for its effect on globe environment, the alternative refrigerant has been paid attention in the refrigeration and heat pump industry. In the present stage, it is found that any pure refrigerant is not a good substitute of HCFC22 for the system in use. The authors have to use binary or ternary refrigerant mixtures as the substitute to meet industrial requirement. But until now, although the heat transfer characteristics of the refrigerant mixtures can be measured in experiments and predicted in some degree, the mass transfer characteristics in condensation process, which is a main part in most systems, can not be clarified by both experimental and theoretical methods. In the present study a non-equilibrium model for condensation of binary refrigerant mixtures inside a horizontal microfin tube is proposed. In this model it is assumed that the phase equilibrium is only established at the vapor-liquid interface, while the bulk vapor and the bulk liquid are in non-equilibrium in the same cross section. The mass transfer characteristic in vapor core is obtained from the analogy between mass and momentum transfer. In the liquid layer, the mass fraction distribution is neglected, but the mass transfer coefficient is treated as infinite that can keep a finite value for the mass transfer rate in liquid phase. From the calculation results compared with the experimental ones for the condensation of HFC134a/HCFC123 and HCFC22/CFC114 mixtures, it is found that the calculated heat flux distribution along the tube axis is in good agreement with that of experiment, and the calculated values of condensing length agree well with the experimental ones. Using the present model, the local mass faction distribution, the diffusion mass transfer rate and the mass transfer characteristics in both vapor and liquid phase are demonstrated. From these results, the effect of mass transfer resistance on condensation heat transfer characteristics for binary
Flooding and mass transfer in Goodloe-packed columns, Part 2
International Nuclear Information System (INIS)
Ayala, J.S.; Brian, B.W.; Sharon, A.C.
1977-01-01
Krypton gas is recovered from HTGR off-gas streams by countercurrent absorption in liquid carbon dioxide. Goodloe stainless steel wire mesh packing was chosen for the absorption columns since the process operates at -20 0 C and about 20 atm pressure. Flooding points and an overall mass transfer coefficient for Goodloe-packed columns were determined with a carbon dioxide-air-water system for 6.4 and 15.2-cm-ID columns. Flood points were obtained for liquid-to-gas mass velocity ratios of 20 to 800. A mixing model, assuming plug flow for the gas and dispersed flow for the liquid, was used to calculate an overall mass transfer coefficient, K/sub L/a. K/sub L/a, based on mass concentrations, ranged from 0.01 to 0.08 sec/sup -T/ and was found to increase with increasing liquid flow rate
Numerical study of heat and mass transfer in inertial suspensions in pipes.
Niazi Ardekani, Mehdi; Brandt, Luca
2017-11-01
Controlling heat and mass transfer in particulate suspensions has many important applications such as packed and fluidized bed reactors and industrial dryers. In this work, we study the heat and mass transfer within a suspension of spherical particles in a laminar pipe flow, using the immersed boundary method (IBM) to account for the solid fluid interactions and a volume of fluid (VoF) method to resolve temperature equation both inside and outside of the particles. Tracers that follow the fluid streamlines are considered to investigate mass transfer within the suspension. Different particle volume fractions 5, 15, 30 and 40% are simulated for different pipe to particle diameter ratios: 5, 10 and 15. The preliminary results quantify the heat and mass transfer enhancement with respect to a single-phase laminar pipe flow. We show in particular that the heat transfer from the wall saturates for volume fractions more than 30%, however at high particle Reynolds numbers (small diameter ratios) the heat transfer continues to increase. Regarding the dispersion of tracer particles we show that the diffusivity of tracers increases with volume fraction in radial and stream-wise directions however it goes through a peak at 15% in the azimuthal direction. European Research Council, Grant No. ERC-2013-CoG- 616186, TRITOS; SNIC (the Swedish National Infrastructure for Computing).
Directory of Open Access Journals (Sweden)
Rosinski Stefan
2003-01-01
Full Text Available On the long way to clinical transplantable hybrid systems, comprising of cells, acting as immuno-protected bioreactors microencapsulated in a polymeric matrix and delivering desired factors (proteins, hormones, enzymes etc to the patient's body, an important step is the optimization of the microcapsule. This topic includes the selection of a proper coating membrane which could fulfil, first of all, the mass transfer as well as biocompatibility, stability and durability requirements. Three different membranes from polymerised aminoacids, formed around exactly identical alginate gel cores, were considered, concerning their mass transport properties, as potential candidates in this task. The results of the evaluation of the mass ingress and mass transfer coefficient h for the selected low molecular mass marker, vitamin B12, in poly-L-lysine (HPLL poly-L-ornithine (HPLO and poly-methylene-co-guanidine hydrochloride (HPMCG membrane alginate microcapsules demonstrate the advantage of using the mass transfer approach to a preliminary screening of various microcapsule formulations. Applying a single marker and evaluating mass transfer coefficients can help to quickly rank the investigated membranes and microcapsules according to their permeability. It has been demonstrated that HPLL, HPLO and HPMCG microcapsules differ from each other by a factor of two concerning the rate of low molecular mass marker transport. Interesting differences in mass transfer through the membrane in both directions in-out was also found, which could possibly be related to the membrane asymmetry.
Study of coupled heat and mass transfer during absorption of ...
Indian Academy of Sciences (India)
2.3 Hydrogen mass balance ε. ∂ρg. ∂t. + div(ρgVg) ... staggered grids to catch the heat transfer across the control volume by convection effectively. .... temperature decreases due to fall in the reaction rate and increase in heat transfer from the.
Effects of Schmidt number on near-wall turbulent mass transfer in pipe flow
Energy Technology Data Exchange (ETDEWEB)
Kang, Chang Woo; Yang, Kyung Soo [Inha University, Incheon (Korea, Republic of)
2014-12-15
Large Eddy simulation (LES) of turbulent mass transfer in circular-pipe flow has been performed to investigate the characteristics of turbulent mass transfer in the near-wall region. We consider a fully-developed turbulent pipe flow with a constant wall concentration. The Reynolds number under consideration is Re{sub r} = 500 based on the friction velocity and the pipe radius, and the selected Schmidt numbers (Sc) are 0.71, 5, 10, 20 and 100. Dynamic subgrid-scale (SGS) models for the turbulent SGS stresses and turbulent mass fluxes were employed to close the governing equations. The current paper reports a comprehensive characterization of turbulent mass transfer in circular-pipe flow, focusing on its near-wall characteristics and Sc dependency. We start with mean fields by presenting mean velocity and concentration profiles, mean Sherwood numbers and mean mass transfer coefficients for the selected values of the parameters. After that, we present the characteristics of fluctuations including root-mean-square (rms) profiles of velocity, concentration, and mass transfer coefficient fluctuations. Turbulent mass fluxes and correlations between velocity and concentration fluctuations are also discussed. The near-wall behaviour of turbulent diffusivity and turbulent Schmidt number is shown, and other authors' correlations on their limiting behaviour towards the pipe wall are evaluated based on our LES results. The intermittent characteristics of turbulent mass transfer in pipe flow are depicted by probability density functions (pdf) of velocity and concentration fluctuations; joint pdfs between them are also presented. Instantaneous snapshots of velocity and concentration fluctuations are shown to supplement our discussion on the turbulence statistics. Finally, we report the results of octant analysis and budget calculation of concentration variance to clarify Sc-dependency of the correlation between near-wall turbulence structures and concentration fluctuation in
Effects of Schmidt number on near-wall turbulent mass transfer in pipe flow
International Nuclear Information System (INIS)
Kang, Chang Woo; Yang, Kyung Soo
2014-01-01
Large Eddy simulation (LES) of turbulent mass transfer in circular-pipe flow has been performed to investigate the characteristics of turbulent mass transfer in the near-wall region. We consider a fully-developed turbulent pipe flow with a constant wall concentration. The Reynolds number under consideration is Re r = 500 based on the friction velocity and the pipe radius, and the selected Schmidt numbers (Sc) are 0.71, 5, 10, 20 and 100. Dynamic subgrid-scale (SGS) models for the turbulent SGS stresses and turbulent mass fluxes were employed to close the governing equations. The current paper reports a comprehensive characterization of turbulent mass transfer in circular-pipe flow, focusing on its near-wall characteristics and Sc dependency. We start with mean fields by presenting mean velocity and concentration profiles, mean Sherwood numbers and mean mass transfer coefficients for the selected values of the parameters. After that, we present the characteristics of fluctuations including root-mean-square (rms) profiles of velocity, concentration, and mass transfer coefficient fluctuations. Turbulent mass fluxes and correlations between velocity and concentration fluctuations are also discussed. The near-wall behaviour of turbulent diffusivity and turbulent Schmidt number is shown, and other authors' correlations on their limiting behaviour towards the pipe wall are evaluated based on our LES results. The intermittent characteristics of turbulent mass transfer in pipe flow are depicted by probability density functions (pdf) of velocity and concentration fluctuations; joint pdfs between them are also presented. Instantaneous snapshots of velocity and concentration fluctuations are shown to supplement our discussion on the turbulence statistics. Finally, we report the results of octant analysis and budget calculation of concentration variance to clarify Sc-dependency of the correlation between near-wall turbulence structures and concentration fluctuation in the
Mass savings domain of plasma propulsion for LEO to GEO transfer
International Nuclear Information System (INIS)
Choueiri, E.Y.; Kelly, A.J.; Jahn, R.G.
1993-01-01
A parametric model is used to study the mass savings of plasma propulsion over advanced chemical propulsion for lower earth orbit (LEO) to geosynchronous orbit (GEO) transfer. Such savings are characterized by stringent requirements of massive payloads (O(10) metric tons) and high power levels (O(100) kW). Mass savings on the order of the payload mass are possible but at the expense of longer transfer times (8--20 months). Typical of the savings domain is the case of a self-field magnetoplasmadynamic (MPD) thruster running quasi-steadily, at an I s of 2000 s, with 600 kW of input power, raising a 50 metric ton satellite in 270 days. The initial mass at LEO will be 65 tons less than a 155 ton LO 2 /LH 2 advanced chemical high thrust spacecraft. An optimum I s can only be found if the cost savings associated with mass savings are counterbalanced by the cost losses incurred by longer transfer times. A simplistic cost model that illustrates the overall trends in the optimization yielded an optimum I s of about 2200 s for a cost effective baseline MPD system
Mass and heat transfer on B7 ordered packing in hydrogen isotope separation by distillation
International Nuclear Information System (INIS)
Croitoru, Cornelia; Pop, Floarea; Titescu, Gheorghe; Stefanescu, Ioan; Trancota, Dan; Peculea, Marius
2002-01-01
This work presents theoretical and experimental data referring to mass and heat transfer on B7 ordered packing in deuterium isotope separation by distillation. The first part is devoted to the study of mass transfer in hydrogen isotopic distillation while the second one treats the mass and heat transfer in water isotopic distillation. A stationary mathematical model for the mass and heat transfer was developed based on multitubular column model with wet wall. This model allowed the calculation starting from theoretical data of the ordered packing efficiency, expressed by the transfer unit height, TUH. Also, from theoretical data the mass and heat transfer coefficients were determined. A test of the mathematical model was performed with the experimental data obtained from two laboratory installations for hydrogen isotope separation by distillation. From the first installation, experimental data concerning the B7 ordered packing efficiency were obtained for the deuterium separation by cryogenic distillation at the - 250 deg C level. With the second one data referring to the mass and heat transfer on the same packing were obtained for the deuterium separation by water distillation under vacuum at the 60 deg C level. The values of TUH, mass and heat transfer coefficients as theoretically evaluate and experimentally checked are in agreement with the respective values obtained in separation processes in chemical industry. This is the fact which endorses utilization of the model of multitubular column with wet wall for describing the transfer processes in distillation columns equipped with B7 ordered packing
Heat and Mass Transfer Model in Freeze-Dried Medium
Alfat, Sayahdin; Purqon, Acep
2017-07-01
There are big problems in agriculture sector every year. One of the major problems is abundance of agricultural product during the peak of harvest season that is not matched by an increase in demand of agricultural product by consumers, this causes a wasted agricultural products. Alternative way was food preservation by freeze dried method. This method was already using heat transfer through conduction and convection to reduce water quality in the food. The main objective of this research was to design a model heat and mass transfer in freeze-dried medium. We had two steps in this research, the first step was design of medium as the heat injection site and the second was simulate heat and mass transfer of the product. During simulation process, we use physical property of some agriculture product. The result will show how temperature and moisture distribution every second. The method of research use finite element method (FEM) and will be illustrated in three dimensional.
Determination of external and internal mass transfer limitation in nitrifying microbial aggregates.
Wilén, Britt-Marie; Gapes, Daniel; Keller, Jürg
2004-05-20
In this article we present a study of the effects of external and internal mass transfer limitation of oxygen in a nitrifying system. The oxygen uptake rates (OUR) were measured on both a macro-scale with a respirometric reactor using off-gas analysis (Titrimetric and Off-Gas Analysis (TOGA) sensor) and on a micro-scale with microsensors. These two methods provide independent, accurate measurements of the reaction rates and concentration profiles around and in the granules. The TOGA sensor and microsensor measurements showed a significant external mass transfer effect at low dissolved oxygen (DO) concentrations in the bulk liquid while it was insignificant at higher DO concentrations. The oxygen distribution with anaerobic or anoxic conditions in the center clearly shows major mass transfer limitation in the aggregate interior. The large drop in DO concentration of 22-80% between the bulk liquid and aggregate surface demonstrates that the external mass transfer resistance is also highly important. The maximum OUR even for floccular biomass was only attained at much higher DO concentrations (approximately 8 mg/L) than typically used in such systems. For granules, the DO required for maximal activity was estimated to be >20 mg/L, clearly indicating the effects of the major external and internal mass transfer limitations on the overall biomass activity. Smaller aggregates had a larger volumetric OUR indicating that the granules may have a lower activity in the interior part of the aggregate. Copyright 2004 Wiley Periodicals, Inc.
International Nuclear Information System (INIS)
Armas, Octavio; Rodriguez, Jose; Payri, Francisco; Martin, Jaime; Agudelo, John R.
2005-01-01
The use of the polytropic coefficient calculation during the compression process in the thermodynamic cycle of a reciprocating internal combustion engine is an interesting tool to minimize errors in the synchronization of pressure and volume signals, and to determine heat flux transferred to the cylinder walls. The accuracy of this calculation depends on the instantaneous values for pressure, volume, trapped mass and its composition, as well as on their variations. In this work the effect of the errors in blow-by, trapped mass and its composition have been studied in detail, specially the effect of errors in the composition estimation, owing to the use of exhaust gas recirculation in typical diesel engines
Modelling mass and heat transfer in nano-based cancer hyperthermia.
Nabil, M; Decuzzi, P; Zunino, P
2015-10-01
We derive a sophisticated mathematical model for coupled heat and mass transport in the tumour microenvironment and we apply it to study nanoparticle delivery and hyperthermic treatment of cancer. The model has the unique ability of combining the following features: (i) realistic vasculature; (ii) coupled capillary and interstitial flow; (iii) coupled capillary and interstitial mass transfer applied to nanoparticles; and (iv) coupled capillary and interstitial heat transfer, which are the fundamental mechanisms governing nano-based hyperthermic treatment. This is an improvement with respect to previous modelling approaches, where the effect of blood perfusion on heat transfer is modelled in a spatially averaged form. We analyse the time evolution and the spatial distribution of particles and temperature in a tumour mass treated with superparamagnetic nanoparticles excited by an alternating magnetic field. By means of numerical experiments, we synthesize scaling laws that illustrate how nano-based hyperthermia depends on tumour size and vascularity. In particular, we identify two distinct mechanisms that regulate the distribution of particle and temperature, which are characterized by perfusion and diffusion, respectively.
DEFF Research Database (Denmark)
Rong, Li; Nielsen, Peter V.; Zhang, Guoqiang
2010-01-01
greatly along the airflow direction on the emission surface. The average mass transfer coefficient increases with higher velocity and turbulence intensity. However, the mass transfer coefficient estimated by CFD simulation is consistently larger than the calculated one by the method using dissociation...... constant and Henry's constant models. In addition, the results show that the liquid-air temperature difference has little impact on the simulated mass transfer coefficient by CFD modeling, whereas the mass transfer coefficient increases with higher liquid temperature using the other method under...... the conditions that the liquid temperature is lower than the air temperature. Although there are differences of mass transfer coefficients between these two methods, the mass transfer coefficients determined by these two methods are significantly related....
Dullaart, R. P. F.; de Vries, R.; Dallinga-Thie, G. M.; van Tol, A.; Sluiter, W. J.
Adipose tissue contributes to plasma levels of lipid transfer proteins and is also the major source of plasma adipokines. We hypothesized that plasma cholesteryl ester transfer protein (CETP) mass, phospholipid transfer protein (PLTP) activity and cholesteryl ester transfer (CET, a measure of CETP
The evolution of the mass-transfer functions in liquid Yukawa systems
Energy Technology Data Exchange (ETDEWEB)
Vaulina, O. S., E-mail: olga.vaulina@bk.ru [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)
2016-09-15
The results of analytic and numerical investigation of mass-transfer processes in nonideal liquid systems are reported. Calculations are performed for extended 2D and 3D systems of particles that interact with a screened Yukawa-type Coulomb potential. The main attention is paid to 2D structures. A new analytic model is proposed for describing the evolution of mass-transfer functions in systems of interacting particles, including the transition between the ballistic and diffusion regimes of their motion.
Light-Time Effect and Mass Transfer in the Triple Star SW Lyncis
Directory of Open Access Journals (Sweden)
Chun-Hwey Kim
1999-06-01
Full Text Available In this paper all the photoelectric times of minimum for the triple star SW Lyn have been analyzed in terms of light-time e ect due to the third-body and secular period decreases induced by mass transfer process. The light-time orbit determined recently by Ogloza et al.(1998 were modi ed and improved. And it is found that the orbital period of SW Lyn have been decreasing secularly. The third-body revolves around the mass center of triple stars every 5y.77 in a highly eccentric elliptical orbit(e=0.61. The third-body with a minimum mass of 1.13M may be a binary or a white dwarf. The rate of secular period-decrease were obtained as ¡âP/P = -12.45 x 10^-11, implying the mass-transfer from the massive primary star to the secondary. The mass losing rate from the primary were calculated as about 1.24 x 10^-8M /y. It is noticed that the mass-transfer in SW Lyn system is opposite in direction to that deduced from it's Roche geometry by previous investigators.
Charge transfer excitations from excited state Hartree-Fock subsequent minimization scheme
International Nuclear Information System (INIS)
Theophilou, Iris; Tassi, M.; Thanos, S.
2014-01-01
Photoinduced charge-transfer processes play a key role for novel photovoltaic phenomena and devices. Thus, the development of ab initio methods that allow for an accurate and computationally inexpensive treatment of charge-transfer excitations is a topic that nowadays attracts a lot of scientific attention. In this paper we extend an approach recently introduced for the description of single and double excitations [M. Tassi, I. Theophilou, and S. Thanos, Int. J. Quantum Chem. 113, 690 (2013); M. Tassi, I. Theophilou, and S. Thanos, J. Chem. Phys. 138, 124107 (2013)] to allow for the description of intermolecular charge-transfer excitations. We describe an excitation where an electron is transferred from a donor system to an acceptor one, keeping the excited state orthogonal to the ground state and avoiding variational collapse. These conditions are achieved by decomposing the space spanned by the Hartree-Fock (HF) ground state orbitals into four subspaces: The subspace spanned by the occupied orbitals that are localized in the region of the donor molecule, the corresponding for the acceptor ones and two more subspaces containing the virtual orbitals that are localized in the neighborhood of the donor and the acceptor, respectively. Next, we create a Slater determinant with a hole in the subspace of occupied orbitals of the donor and a particle in the virtual subspace of the acceptor. Subsequently we optimize both the hole and the particle by minimizing the HF energy functional in the corresponding subspaces. Finally, we test our approach by calculating the lowest charge-transfer excitation energies for a set of tetracyanoethylene-hydrocarbon complexes that have been used earlier as a test set for such kind of excitations
Bibliography on augmentation of convective heat and mass transfer
International Nuclear Information System (INIS)
Bergles, A.E.; Webb, R.L.; Junkhan, G.H.; Jensen, M.K.
1979-05-01
Heat transfer augmentation has developed into a major specialty area in heat transfer research and development. A bibliography of world literature on augmentation is presented. The literature is classified into passive augmentation techniques, which require no external power, and active techniques, which do require external power. The fourteen techniques are grouped in terms of their application to the various modes of heat transfer. Mass transfer is included for completeness. Key words are included with each citation for technique/mode identification. The total number of publications cited is 1,967, including 75 surveys of various techniques and 42 papers on performance evaluation of passive techniques. Patents are not included as they will be the subject of a future topical report
One loop corrections to the lightest Higgs mass in the minimal η model with a heavy Z'
International Nuclear Information System (INIS)
Comelli, D.
1992-06-01
We have evaluated the one loop correction to the bound on the lightest Higgs mass valid in the minimal, E 6 based, supersymmetric η model in the presence of a 'heavy' Z', M z' ≥1 TeV. The dominant contribution from the fermion sfermion sector increases the 108 GeV tree level value by an amount that depends on the top mass in a way that is largely reminescent of minimal SUSY models. For M t ≤150 GeV, Msub(t tilde)=1 TeV, the 'light' Higgs mass is always ≤130 GeV. (orig.)
Study of coupled heat and mass transfer during absorption of ...
Indian Academy of Sciences (India)
(iii) The gas phase is ideal from thermodynamic point of view. (iv) Only mass transfer and no heat transfer takes place through the porous filter. (v) The thermal conductivity and specific heat of the hydride bed are assumed to be constant. This assumption underestimates the bed performance slightly, because in actual case ...
Momentum, heat, and mass transfer analogy for vertical hydraulic transport of inert particles
Directory of Open Access Journals (Sweden)
Jaćimovski Darko R.
2014-01-01
Full Text Available 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 (γ*=0, occurs at a critical voidage ε≈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 (Re15000, 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. [Projekat Ministarstva nauke Republike Srbije, br. 172022
A mass transfer based variable porosity model with particle radius change for a Lithium-ion battery
International Nuclear Information System (INIS)
Ashwin, T.R.; McGordon, A.; Jennings, P.A.
2017-01-01
Highlights: • Mass transfer based model to calculate the porosity variation and radius change. • Can be used with any model that calculates Lithium concentration in electrolyte. • Considers SEI as a mass deposition rather than simply an internal resistance. • Brings more accuracy to the volume specific area and the Butler-Volmer kinetics • Practical applicability in pre-lithiation, lithium plating and stress calculation. - Abstract: Micro pore-clogging in the electrodes due to SEI growth and other side reactions can cause adverse effects on the performance of a Lithium-ion battery. The fundamental problem of volume fraction variation and particle radius change during the charge-discharge process in a lithium-ion battery is modelled in this paper with the help of mass transfer based formulation and demonstrated on a battery with LiCoO_2 chemistry. The model can handle the volume fraction change due to intercalation reaction, solvent reduction side reaction and the electrolyte density change due to side reaction contamination in the battery. The entire calculation presented in this paper models particle radius and volume fraction together and therefore gives greater accuracy in calculating the volume-specific-area of the reacting particles which is an important parameter controlling the Butler-Volmer kinetics. The mass deposit on the electrode (or loss of lithium) gives an indication of the amount of pre-lithiation required to maintain cell performance while the amount of mass deposited on the SEI helps to decide the safe operating condition for which the clogging of pores and capacity fade will be minimal. Moreover the model presented in this paper has wide applicability in analysing the stress development inside the battery due to irreversible porous filling.
Xiong, Jun Ying
2016-12-29
A comprehensive analysis of fluid motion, mass transport, thermodynamics and power generation during pressure retarded osmotic (PRO) processes was conducted. This work aims to (1) elucidate the fundamental relationship among various membrane properties and operation parameters and (2) analyse their individual and combined impacts on PRO module performance. A state-of-the-art inner-selective thin-film composite (TFC) hollow fiber membrane was employed in the modelling. The analyses of mass transfer and Gibbs free energy of mixing indicate that the asymmetric nature of hollow fibers results in more significant external concentration polarization (ECP) in the lumen side of the inner-selective hollow fiber membranes. In addition, a trade-off relationship exists between the power density (PD) and the specific energy (SE). The PD vs. SE trade-off upper bound may provide a useful guidance whether the flowrates of the feed and draw solutions should be further optimized in order to (1) minimize the boundary thickness and (2) maximize the osmotic power generation. Two new terms, mass transfer efficiency and power harvesting efficiency for osmotic power generation, have been proposed. This work may provide useful insights to design and operate PRO modules with enhanced performance so that the PRO process becomes more promising in real applications in the near future.
Interferometric study of mass transfer enchancement by turbulence promoters
International Nuclear Information System (INIS)
Hanson, K.J.
1979-04-01
The use of small obstacles to thin the downstream mass transfer boundary layer has been investigated with a traveling, dual-beam laser interferometer. Plots of boundary layer thickness as a function of the distance from the leading edge of the electrode were developed to study the effects of obstacle shape, the distance of the obstacle from the electrode surface, and Reynolds number for the purposes of determining the optimum conditions to achieve high mass transfer rates. Parameters which characterize the efficiency of the obstacles, the minimum boundary layer thickness in the wake, and the recovery distance downstream of each obstacle have been introduced to quantitatively describe the results. In addition, the effect of local turbulence near the obstacles on the deposit morphology has been described
The influence of pH on gas-liquid mass transfer in non-Newtonian fluids
Li Shaobai; Fan Jungeng; Xu Shuang; Li Rundong; Luan Jingde
2017-01-01
In this study, the effect of pH on the mass transfer of oxygen bubble swarms in non-Newtonian fluids was experimentally studied. The volumetric liquid side mass transfer coefficient (kLa), liquid side mass transfer coefficient (kL), and specific interfacial area (a) were investigated. The pH was regulated by the addition of hydrochloric acid and sodium hydroxide (NaOH). It was found that the kLa increased with the gas flow rate increasing and decreased with the apparent viscosity of the liqui...
Modelling toluene oxidation : Incorporation of mass transfer phenomena
Hoorn, J.A.A.; van Soolingen, J.; Versteeg, G. F.
The kinetics of the oxidation of toluene have been studied in close interaction with the gas-liquid mass transfer occurring in the reactor. Kinetic parameters for a simple model have been estimated on basis of experimental observations performed under industrial conditions. The conclusions for the
Calculation of the mass transfer coefficient for the combustion of a carbon particle
Energy Technology Data Exchange (ETDEWEB)
Scala, Fabrizio [Istituto di Ricerche sulla Combustione - CNR, P.le Tecchio 80, 80125 Napoli (Italy)
2010-01-15
In this paper we address the calculation of the mass transfer coefficient around a burning carbon particle in an atmosphere of O{sub 2}, N{sub 2}, CO{sub 2}, CO, and H{sub 2}O. The complete set of Stefan-Maxwell equations is analytically solved under the assumption of no homogeneous reaction in the boundary layer. An expression linking the oxygen concentration and the oxygen flux at the particle surface (as a function of the bulk gas composition) is derived which can be used to calculate the mass transfer coefficient. A very simple approximate explicit expression is also given for the mass transfer coefficient, that is shown to be valid in the low oxygen flux limit or when the primary combustion product is CO{sub 2}. The results are given in terms of a correction factor to the equimolar counter-diffusion mass transfer coefficient, which is typically available in the literature for specific geometries and/or fluid-dynamic conditions. The significance of the correction factor and the accuracy of the different available expressions is illustrated for several cases of practical interest. Results show that under typical combustion conditions the use of the equimolar counter-diffusion mass transfer coefficient can lead to errors up to 10%. Larger errors are possible in oxygen-enriched conditions, while the error is generally low in oxy-combustion. (author)
Extraction of chlorophyll from pandan leaves using ethanol and mass transfer study
Directory of Open Access Journals (Sweden)
Putra Meilana Dharma
2017-01-01
Full Text Available Green pigments are used in many industrial branches including food, drinks, soap and cosmetics. Chlorophyll can substitute synthetic dyes which may affect health. Chlorophyll can be extracted from pandan leaves; the pandan crop grows in many tropical areas. The effects of temperature, 30–70°C and agitation speed, 100–400 rpm on chlorophyll extraction from pandan leaves, using ethanol and the evaluation of mass transfer coefficient, using dimensionless analysis were investigated. The optimal conditions of extraction was obtained at 60°C and 300 rpm; the chlorophyll concentration was 107.1 mg L-1. The volumetric mass transfer coefficient increased with the temperature and agitation speed. Determination of volumetric mass transfer coefficient and dimensionless correlations are useful for further process development or industrial applications.
A mass transfer origin for blue stragglers in NGC 188 as revealed by half-solar-mass companions.
Geller, Aaron M; Mathieu, Robert D
2011-10-19
In open star clusters, where all members formed at about the same time, blue straggler stars are typically observed to be brighter and bluer than hydrogen-burning main-sequence stars, and therefore should already have evolved into giant stars and stellar remnants. Correlations between blue straggler frequency and cluster binary star fraction, core mass and radial position suggest that mass transfer or mergers in binary stars dominates the production of blue stragglers in open clusters. Analytic models, detailed observations and sophisticated N-body simulations, however, argue in favour of stellar collisions. Here we report that the blue stragglers in long-period binaries in the old (7 × 10(9)-year) open cluster NGC 188 have companions with masses of about half a solar mass, with a surprisingly narrow mass distribution. This conclusively rules out a collisional origin, as the collision hypothesis predicts a companion mass distribution with significantly higher masses. Mergers in hierarchical triple stars are marginally permitted by the data, but the observations do not favour this hypothesis. The data are highly consistent with a mass transfer origin for the long-period blue straggler binaries in NGC 188, in which the companions would be white dwarfs of about half a solar mass.
Mass transfer between a fluid and an immersed object in liquid–solid packed and fluidized beds
Directory of Open Access Journals (Sweden)
NEVENKA BOSKOVIC-VRAGOLOVIC
2005-11-01
Full Text Available Themass transfer coefficient between fluid and an immersed sphere in liquid packed and fluidized beds of inert spherical particles have been studied experimentally using a column 40 mm in diameter. The mass transfer data were obtained by studying the transfer of benzoic acid from the immersed sphere to flowing water using the dissolution method. In all runs, the mass transfer rates were determined in the presence of inert glass particles 0.50-2.98 mm in diameter. The influence of different parameters, such as: liquid velocity, particles size and bed voidage, on the mass transfer in packed and fluidized beds is presented. The obtained experimental data for mass transfer in the packed and particulate fluidized bed were correlated by a single correlation, thus confirming the similarity between the two systems.
Triviality bound on lightest Higgs mass in next to minimal supersymmetric model
International Nuclear Information System (INIS)
Choudhury, S.R.; Mamta; Dutta, Sukanta
1998-01-01
We study the implication of triviality on Higgs sector in next to minimal supersymmetric model (NMSSM) using variational field theory. It is shown that the mass of the lightest Higgs boson in NMSSM has an upper bound ∼ 10 M w which is of the same order as that in the standard model. (author)
RESEARCH OF THE MASS TRANSFER AT MEMBRANE CLEANING OF BIOGAZ
Directory of Open Access Journals (Sweden)
Marat SATAYEV
2015-04-01
Full Text Available Everyone has long known the benefits and effectiveness of biogas. Particularly, getting biogas from the agricultural waste is very promising. But, the question is if we can use such a useful and effective biogas at 100%. Today, we use only a half of the benefit, because to get the biogas we spend more energy than we get. In this regard, the work on the study of the biogas development is extremely important. The study of the biogas formation requires numerous experiments. This article analyzes the biogas mass transfer with the membrane purification and identification of the of mass transfer mechanisms through the membrane pores.
Brusseau, Mark L.; Guo, Zhilin
2018-01-01
It is evident based on historical data that groundwater contaminant plumes persist at many sites, requiring costly long-term management. High-resolution site-characterization methods are needed to support accurate risk assessments and to select, design, and operate effective remediation operations. Most subsurface characterization methods are generally limited in their ability to provide unambiguous, real-time delineation of specific processes affecting mass-transfer, transformation, and mass removal, and accurate estimation of associated rates. An integrated contaminant elution and tracer test toolkit, comprising a set of local-scale groundwater extraction-and injection tests, was developed to ameliorate the primary limitations associated with standard characterization methods. The test employs extended groundwater extraction to stress the system and induce hydraulic and concentration gradients. Clean water can be injected, which removes the resident aqueous contaminant mass present in the higher-permeability zones and isolates the test zone from the surrounding plume. This ensures that the concentrations and fluxes measured within the isolated area are directly and predominantly influenced by the local mass-transfer and transformation processes controlling mass removal. A suite of standard and novel tracers can be used to delineate specific mass-transfer and attenuation processes that are active at a given site, and to quantify the associated mass-transfer and transformation rates. The conceptual basis for the test is first presented, followed by an illustrative application based on simulations produced with a 3-D mathematical model and a brief case study application.
INTENSIFICATION OF HEAT- AND MASS TRANSFER IN EVAPORATION - CONDENSATION DEVICES
Directory of Open Access Journals (Sweden)
A. G. Kulakov
2005-01-01
Full Text Available Results of investigation of capillary structure properties used in evaporation – condensation devices are presented.Constructive solutions for intensification of heat transfer in evaporation and condensation heat exchangers are offered. The obtained heat transfer experimental data at film-type vapor conden-sation are generalized in criterion form.Description of general rule of heat and mass transfer processes in miniature heat pipes with three various capillary structures at wide range of operating parameters is given in the paper.
Mass transfer coefficient in ginger oil extraction by microwave hydrotropic solution
Handayani, Dwi; Ikhsan, Diyono; Yulianto, Mohamad Endy; Dwisukma, Mandy Ayulia
2015-12-01
This research aims to obtain mass transfer coefficient data on the extraction of ginger oil using microwave hydrotropic solvent as an alternative to increase zingiberene. The innovation of this study is extraction with microwave heater and hydrotropic solvent,which able to shift the phase equilibrium, and the increasing rate of the extraction process and to improve the content of ginger oil zingiberene. The experiment was conducted at the Laboratory of Separation Techniques at Chemical Engineering Department of Diponegoro University. The research activities carried out in two stages, namely experimental and modeling work. Preparation of the model postulated, then lowered to obtain equations that were tested and validated using data obtained from experimental. Measurement of experimental data was performed using microwave power (300 W), extraction temperature of 90 ° C and the independent variable, i.e.: type of hydrotropic, the volume of solvent and concentration in order, to obtain zingiberen levels as a function of time. Measured data was used as a tool to validate the postulation, in order to obtain validation of models and empirical equations. The results showed that the mass transfer coefficient (Kla) on zingiberene mass transfer models ginger oil extraction at various hydrotropic solution attained more 14 ± 2 Kla value than its reported on the extraction with electric heating. The larger value of Kla, the faster rate of mass transfer on the extraction process. To obtain the same yields, the microwave-assisted extraction required one twelfth time shorter.
Heat And Mass Transfer Analysis of a Film Evaporative MEMS Tunable Array
O'Neill, William J.
This thesis details the heat and mass transfer analysis of a MEMs microthruster designed to provide propulsive, attitude control and thermal control capabilities to a cubesat. This thruster is designed to function by retaining water as a propellant and applying resistive heating in order to increase the temperature of the liquid-vapor interface to either increase evaporation or induce boiling to regulate mass flow. The resulting vapor is then expanded out of a diverging nozzle to produce thrust. Because of the low operating pressure and small length scale of this thruster, unique forms of mass transfer analysis such as non-continuum gas flow were modeled using the Direct Simulation Monte Carlo method. Continuum fluid/thermal simulations using COMSOL Multiphysics have been applied to model heat and mass transfer in the solid and liquid portions of the thruster. The two methods were coupled through variables at the liquid-vapor interface and solved iteratively by the bisection method. The simulations presented in this thesis confirm the thermal valving concept. It is shown that when power is applied to the thruster there is a nearly linear increase in mass flow and thrust. Thus, mass flow can be regulated by regulating the applied power. This concept can also be used as a thermal control device for spacecraft.
Analysis of mass transfer characteristics in a tubular membrane using CFD modeling.
Yang, Jixiang; Vedantam, Sreepriya; Spanjers, Henri; Nopens, Ingmar; van Lier, Jules B
2012-10-01
In contrast to the large amount of research into aerobic membrane bioreactors, little work has been reported on anaerobic membrane bioreactors (AMBRs). As to the application of membrane bioreactors, membrane fouling is a key issue. Membrane fouling generally occurs more seriously in AMBRs than in aerobic membrane bioreactors. However, membrane fouling could be managed through the application of suitable shear stress that can be introduced by the application of a two-phase flow. When the two-phase flow is applied in AMBRs, little is known about the mass transfer characteristics, which is of particular importance, in tubular membranes of AMBRs. In our present work, we have employed fluid dynamic modeling to analyze the mass transfer characteristics in the tubular membrane of a side stream AMBR in which, gas-lift two-phase flow was applied. The modeling indicated that the mass transfer capacity at the membrane surface at the noses of gas bubbles was higher than the mass transfer capacity at the tails of the bubbles, which is in contrast to the results when water instead of sludge is applied. At the given mass transfer rate, the filterability of the sludge was found to have a strong influence on the transmembrane pressure at a steady flux. In addition, the model also showed that the shear stress in the internal space of the tubular membrane was mainly around 20 Pa but could be as high as about 40 Pa due to gas bubble movements. Nonetheless, at these shear stresses a stable particle size distribution was found for sludge particles. Copyright © 2012 Elsevier Ltd. All rights reserved.
Lee, Jung Gil; Jeong, Sanghyun; Alsaadi, Ahmad Salem; Ghaffour, NorEddine
2017-01-01
(>2.1×10−6kg/m2sPa: membranes under development) were simulated using an experimentally validated model at different ranges of convection heat transfer by varying the inlet flow rates and spacer enhancement factor. The effect of mass transfer
Convective heat and mass transfer in rotating disk systems
Shevchuk, Igor V
2009-01-01
The book describes results of investigations of a series of convective heat and mass transfer problems in rotating-disk systems. Methodology used included integral methods, self-similar and approximate analytical solutions, as well as CFD.
Mass transfer during sulfuric acid concentration by evaporation into the air flow
Directory of Open Access Journals (Sweden)
V. K. Lukashov
2016-12-01
Full Text Available This article shows the results of the study of mass transfer under periodic concentration of sulfuric acid by evaporation inthe gas flow, neutral with respect to the components of acid.Used mathematical model for mass transferbases on the proposed simplified physical representations.This model has allowed to construct an algorithm for calculation the coefficient of mass transfer from the liquid phase into the gas flow. The algorithm uses the experimental data of change the amount of acid and concentration of the water taken from the laboratory tests. Time-based Nusselt diffusion criterion represent the results of the study at different modes of the evaporation process.It has been found that the character of the influence of temperature and initial acid concentration on Nusselt diffusion criterion depends on the variation range of the mass fraction of water in the acid.It is shown that these dependences are well approximated by an exponential function from the dimensionless parameters of the process. This allows usingthem for calculation the mass transfer coefficient into the gas phase in a batch process of concentrating in the range of investigated modes.
Robust Modelling of Heat and Mass Transfer in Processing of Solid Foods
DEFF Research Database (Denmark)
Feyissa, Aberham Hailu
The study is focused on combined heat and mass transfer during processing of solid foods such as baking and frying processes. Modelling of heat and mass transfer during baking and frying is a significant scientific challenge. During baking and frying, the food undergoes several changes...... in microstructure and other physical properties of the food matrix. The heat and water transport inside the food is coupled in a complex way, which for some food systems it is not yet fully understood. A typical example of the latter is roasting of meat in convection oven, where the mechanism of water transport...... is unclear. Establishing the robust mathematical models describing the main mechanisms reliably is of great concern. A quantitative description of the heat and mass transfer during the solid food processing, in the form of mathematical equations, implementation of the solution techniques, and the value...
Convective mass transfer in helical pipes: effect of curvature and torsion
Energy Technology Data Exchange (ETDEWEB)
Litster, S.; Djilali, N. [University of Victoria, Department of Mechanical Engineering, Victoria, BC (Canada); Pharoah, J.G. [University of Victoria, Department of Mechanical Engineering, Victoria, BC (Canada); Queen' s University at Kingston, Department of Mechanical Engineering, Kingston, ON (Canada)
2006-03-01
A 3D numerical analysis of the flow and mass transfer in helical pipes is presented. The interpretation of the flow patterns and their impact on mass transfer is shown to require a non-orthogonal pseudo-stream function based visualization. The strong coupling between torsion and curvature effects, and the resulting secondary flow regimes are well characterized by a parameter combining both the Dean (Dn) and Germano numbers (Gn). For membrane separation applications, helical modules combining high curvature with low torsion would alleviate concentration polarization and yield appreciable flux improvement. (orig.)
Electromagnetic control of mass transfer at liquid/liquid interfaces
International Nuclear Information System (INIS)
Saadi, B.
2006-04-01
Most metallurgical processes, such as steel refining or nuclear waste processing; the interfaces between two liquid phases are the regions of mass transfer. These transfers require the implementation of a means of stirring to accelerate the kinetics of the pollutants transfer between both phases. This thesis deals with the use of the electromagnetic forces to stir, without any material contact, the bath core and the interface in order to control or even increase the kinetic transfers. To achieve this, two complementary experimental installations were used. The first experiment allows the measurement of the Indium transfer, initially dissolved in mercury towards a covering electrolyte layer and the velocity field in mercury. The performed experiments, determine the topology of the fields flows speeds in the mercury bath, moreover the behaviour of the transfer kinetics versus the intensity of the magnetic field are established. This evolution is correlated with the dynamic behaviour of the mercury surface. The second installation allows the characterization of an element transfer (Pb, Zr or Ce) initially contained in a fluorinated salt towards an antimony matrix containing lithium. It appears that all transfers kinetics are very fast. The proposed experimental set-up is particularly efficient for Cerium transfer (limited by the interface) but does not present any action for Zirconium transfer. (author)
Racz, I.G.; Groot Wassink, J.; Klaassen, R.
1986-01-01
Concentration polarisation, decreasing the efficiency in membrane separation processes, can be reduced by increasing mass transfer between membrane surface and bulk of the feed stream. Analogous to techniques used in plate heat exchangers efforts have been made to enhance mass transfer in a plate
Marcelis, C.L.M.; Leeuwen, van M.; Polderman, H.G.; Janssen, A.J.H.; Lettinga, G.
2003-01-01
A mathematical model was developed in order to describe the mass transfer rate of dibenzothiophene within the oil droplet to the oil/water interface of droplets created in a stirred tank reactor. The mass transfer rate of dibenzothiophene was calculated for various complex hydrocarbon distillates
Closing in on minimal dark matter and radiative neutrino masses
Energy Technology Data Exchange (ETDEWEB)
Sierra, D. Aristizabal [IFPA, Dép. AGO, Université de Liège, Bât B5, Sart Tilman B-4000 Liège 1 (Belgium); Departamento de Física, Universidad Técnica Federico Santa María, Casilla 110-V, Avda. España 1680, Valparaiso (Chile); Simoes, C.; Wegman, D. [IFPA, Dép. AGO, Université de Liège, Bât B5, Sart Tilman B-4000 Liège 1 (Belgium)
2016-06-20
We study one-loop radiative neutrino mass models in which one of the beyond-the-standard model fields is either a hypercharge-zero fermion quintet (minimal dark matter) or a hypercharge-zero scalar septet. By systematically classifying all possible one-loop such models we identify various processes that render the neutral component of these representations (dark matter) cosmologically unstable. Thus, our findings show that these scenarios are in general not reconcilable with dark matter stability unless tiny couplings or additional ad hoc symmetries are assumed, in contrast to minimal dark matter models where stability is entirely due to the standard model gauge symmetry. For some variants based on higher-order loops we find that α{sub 2} reaches a Landau pole at rather low scales, a couple orders of magnitude from the characteristic scale of the model itself. Thus, we argue that some of these variations although consistent with dark matter stability and phenomenological constraints are hard to reconcile with perturbativity criteria.
Membrane introduction proton-transfer-reaction mass spectrometry
International Nuclear Information System (INIS)
Alexander, M.; Boscaini, E.; Maerk, T.; Lindinger, W.
2002-01-01
Proton-transfer-reaction mass spectrometry (PTR-MS) is a rapidly expanding field with multiple applications in ion physics, atmospheric chemistry, food chemistry, volatile organic compounds monitoring and biology. Initial studies that combine PTR-MS and membrane introduction mass spectrometry (MIMS) were researched and outlined. First using PTR-MS, certain fundamental physical properties of a poly-dimethylsiloxane (PDMS) membrane including solubilities and diffusion coefficients were measured. Second, it was shown how the chemical selectivity of the (PDMS) can be used to extend the capabilities of the PTR-MS instrument by eliminating certain isobaric interferences and excluding water from volatile organic compounds (VOCs). Experiments with mixtures of several VOCs (toluene, benzene, acetone, propanal, methanol) are presented. (nevyjel)
Mass transfer and slag-metal reaction in ladle refining : a CFD approach
Ramström, Eva
2009-01-01
In order to optimise the ladle treatment mass transfer modelling of aluminium addition and homogenisation time was carried out. It was stressed that incorporating slag-metal reactions into the mass transfer modelling strongly would enhance the reliability and amount of information to be analyzed from the CFD calculations. In the present work, a thermodynamic model taking all the involved slag metal reactions into consideration was incorporated into a 2-D fluid flow model of an argon stirr...
Energy Technology Data Exchange (ETDEWEB)
Day-Lewis, Frederick; Singha, Kamini; Haggerty, Roy; Johnson, Timothy; Binley, Andrew; Lane, John
2014-03-10
. In this project, we sought to capitalize on the geophysical signatures of mass transfer. Previous numerical modeling and pilot-scale field experiments suggested that mass transfer produces a geoelectrical signature—a hysteretic relation between sampled (mobile-domain) fluid conductivity and bulk (mobile + immobile) conductivity—over a range of scales relevant to aquifer remediation. In this work, we investigated the geoelectrical signature of mass transfer during tracer transport in a series of controlled experiments to determine the operation of controlling parameters, and also investigated the use of complex-resistivity (CR) as a means of quantifying mass transfer parameters in situ without tracer experiments. In an add-on component to our grant, we additionally considered nuclear magnetic resonance (NMR) to help parse mobile from immobile porosities. Our study objectives were to: 1. Develop and demonstrate geophysical approaches to measure mass-transfer parameters spatially and over a range of scales, including the combination of electrical resistivity monitoring, tracer tests, complex resistivity, nuclear magnetic resonance, and materials characterization; and 2. Provide mass-transfer estimates for improved understanding of contaminant fate and transport at DOE sites, such as uranium transport at the Hanford 300 Area. To achieve our objectives, we implemented a 3-part research plan involving (1) development of computer codes and techniques to estimate mass-transfer parameters from time-lapse electrical data; (2) bench-scale experiments on synthetic materials and materials from cores from the Hanford 300 Area; and (3) field demonstration experiments at the DOE’s Hanford 300 Area.
Numerical Study on Mass Transfer of a Vapor Bubble Rising in Very High Viscous Fluid
Directory of Open Access Journals (Sweden)
T. Kunugi
2014-09-01
Full Text Available This study focused on a bubble rising behavior in a molten glass because it is important to improve the efficiency of removal of bubbles from the molten glass. On the other hand, it is expected that some gas species which exists in a bubble are transferred into the molten glass through the bubble interface, i.e., the mass transfer, subsequently, it may cause a bubble contraction in the molten glass. In this paper, in order to understand the bubble rising behavior with its contraction caused by the mass transfer through the bubble interface in the very high viscous fluid such as the molten glass, a bubble contraction model has been developed. The direct numerical simulations based on the MARS (Multi-interface Advection and Reconstruction Solver coupled with the mass transfer equation and the bubble contraction model regarding the mass transfer from the rising bubble in very high viscous fluid have been performed. Here, the working fluids were water vapor as the gas species and the molten glass as the very high viscous fluid. Also, the jump conditions at the bubble interface for the mass transfer were examined. Furthermore, the influence of the bubble contraction for the bubble rising compared to that in the water as a normal viscous fluid was investigated. From the result of the numerical simulations, it was found that the bubble rising behavior was strongly affected not only by the viscosity of the working fluid but also by the bubble contraction due to the mass transfer through the bubble interface.
Mass transfer processes and field-scale transport of organic solutes
International Nuclear Information System (INIS)
Brusseau, M.L.
1990-01-01
The influence of mass transfer processes, such as sorption/desorption and mass transfer between immiscible liquids and water, on the transport of organic solutes is discussed. Rate-limited sorption of organic solutes caused by a diffusion-constrained mechanism is shown to be significant under laboratory conditions. The significance of the impact of nonequilibrium sorption on field-scale transport is scale dependent. The impact of organic liquids on mass transfer and transport of organic solutes depends upon the nature of the solute and the nature and form of the organic liquid. For example, while retardation of nonionic solutes is decreased in mixed-solvent systems, (i.e. systems comprised of water and a miscible organic liquid or an immiscible liquid present in concentrations below phase separation), the retardation of organic acids may, in some cases, increase with addition of a cosolvent. While the presence of an immiscible liquid existing as a mobile phase will reduce retention of organic solutes, the presence of residual saturation of an immiscible liquid can significantly increase retention. A model is presented that incorporates the effects of retention resulting from residual saturation, as well as nonequilibrium sorption, on the transport of organic solutes. (Author) (70 refs., 3 figs.)
A review of near-field mass transfer in geologic disposal systems
International Nuclear Information System (INIS)
Pigford, T.H.; Chambre, P.L.; Lee, W.W.L.
1990-02-01
In this report we summarize the analyses of the time-dependent mass transfer of radionuclides from a waste solid into surrounding porous or fractured media that have been developed at the University of California, Berkeley. For each analysis we describe the conceptual model, we present the governing equations and the resulting analytic solutions, and we illustrate the results. Designers of geologic disposal systems for solid waste must predict the long-term time-dependent rate of dissolution of toxic contaminants in ground water, to provide the source term for predicting the later transport of these contaminants to the environment. Mass-transfer analysis is being used to predict rates of dissolution and release of radioactive constituents in future repositories for high-level radioactive waste, and it has been applied to predict the life of a copper container for high-level radioactive waste. Mechanistic analysis of mass-transfer is based on well-established theory of diffusive-convective transport. Its application requires experimental measurement of well-defined parameters such as porosity, solubility, diffusion coefficient, and pore velocity. Our first analysis assumed a waste solid in direct contact with porous rock. Subsequently we analyzed the more realistic situations of backfill between the waste and rock, rock with discrete fractures as well as pores, and the effects of waste constituents of high solubility. Those dealing with specifically with mass transfer in the near field are presented here. In order to have a consistent set of notation within this review, some of the notation here is different than in the reports cited. 71 refs., 47 figs., 7 tabs
Evaluation of mixing and mass transfer in a stirred pilot scale bioreactor utilizing CFD
DEFF Research Database (Denmark)
Bach, Christian; Yang, Jifeng; Larsson, Hilde Kristina
2017-01-01
Knowledge and prediction of mixing and mass transfer in agitated bioreactors is fundamental for process development and scale up. In particular key process parameters such as mixing time and volumetric mass transfer coefficient are essential for bioprocess development. In this work the mixing...... and mass transfer performance of a high power agitated pilot scale bioreactor has been characterized using a novel combination of computational fluid dynamics (CFD) and experimental investigations. The effect of turbulence inside the vessel was predicted using a standard RANS k-ε model. Mixing time...... transfer coefficients were in accordance with the experimental data. This work illustrates the possibility of predicting the two phase fluid dynamic performance of an agitated pilot scale bioreactor using validated CFD models. These models can be applied to illustrate the effect of changing the physical...
Cryogenic Fluid Transfer Components Using Single Crystal Piezoelectric Actuators, Phase I
National Aeronautics and Space Administration — Cryogenic fluid transfer components using single crystal piezoelectric actuators are proposed to enable low thermal mass, minimal heat leak, low power consumption...
Cryogenic Fluid Transfer Components Using Single Crystal Piezoelectric Actuators, Phase II
National Aeronautics and Space Administration — Cryogenic fluid transfer components using single crystal piezoelectric actuators are proposed to enable low thermal mass, minimal heat leak, low power consumption...
Biofilm structure and mass transfer in a gas phase trickle-bed biofilter.
Zhu, X; Suidan, M T; Alonso, C; Yu, T; Kim, B J; Kim, B R
2001-01-01
Mass transport phenomena occurring in the biofilms of gas phase trickle-bed biofilters are investigated in this study. The effect of biofilm structure on mass transfer mechanisms is examined using experimental observation from the operating of biofilters, microelectrode techniques and microscopic examination. Since the biofilms of biofilters used for waste gas treatment are not completely saturated with water, there is not a distinguishable liquid layer outside the biofilm. Results suggest that due to this characteristic, gas phase substrates (such as oxygen or volatile organic compounds) may not be limited by the aqueous phase because transport of the compound into the biofilm can occur directly through non-wetted areas. On the other hand, for substrates that are present only in the liquid phase, such as nitrate, the mass transfer limitation is more serious because of the limited liquid supply. Microscopic observations show that a layered structure with void spaces exists within the biofilm. Oxygen concentration distributions along the depth of the biofilms are examined using an oxygen microelectrode. Results indicate that there are some high dissolved oxygen zones inside the biofilm, which suggests the existence of passages for oxygen transfer into the deeper sections of the biofilm in a gas phase trickle-bed biofilter. Both the low gas-liquid mass transfer resistance and the resulting internal structure contribute to the high oxygen penetration within the biofilms in gas phase trickle-bed biofilters.
MASS TRANSFER IN FERMENTATION PROCESSES
Directory of Open Access Journals (Sweden)
A. Shevchenko
2018-04-01
Full Text Available The peculiarities of anaerobic fermentation processes with the accumulation of dissolved ethyl alcohol and carbon dioxide in the culture media are considered in the article.The solubility of CO2 is limited by the state of saturation in accordance with Henry’s law. This, with all else being equal, limits the mass transfer on the interface surface of yeast cells and the liquid phase of the medium. A phenomenological model of the media restoration technologies based on the unsaturation index on СО2 is developed. It is shown that this restoration in the existing technologies of fermentation of sugar-rich media occurs, to a limited extent, in self-organized flow circuits, with variable values of temperatures and hydrostatic pressures, due to the creation of unsaturated local zones.It is shown that increasing the height of the media in isovolumetric apparatuses leads to an increase in the levels of flow circuits organization and to the improvement of the desaturation and saturation modes of the liquid phase and intensification of mass transfer processes. Among the deterministic principles of restoring the saturation possibilities of the media, there are forced variables of pressures with time pauses on their lower and upper levels. In such cases, the possibilities of short-term intensive desaturations in full media volumes, the restoration of their saturation perception of CO2, and the activation of fermentation processes are achieved. This direction is technically feasible for active industrial equipment.The cumulative effect of the action of variable pressures and temperatures corresponds to the superposition principle, but at the final stages of fermentation, the pressure and temperature values are leveled, so the restoration of the unsaturation state slows down to the level of the bacteriostatic effect. The possibility of eliminating the disadvantages of the final stage of fermentation by means of programmable variable pressures is shown
Dynamics of Mass Transfer in Wide Symbiotic Systems
de Val-Borro, Miguel; Karovska, M.; Sasselov, D.
2010-01-01
We investigate the formation of accretion disks around the secondary in detached systems consisting of an Asymptotic Giant Branch (AGB) star and a compact accreting companion as a function of mass loss rate and orbital parameters. In particular, we study winds from late-type stars that are gravitationally focused by a companion in a wide binary system using hydrodynamical simulations. For a typical slow and massive wind from an evolved star there is a stream flow between the stars with accretion rates of a few percent of the mass loss from the primary. Mass transfer through a focused wind is an important mechanism for a broad range of interacting binary systems and can explain the formation of Barium stars and other chemically peculiar stars.
Effect of minimal length uncertainty on the mass-radius relation of white dwarfs
Mathew, Arun; Nandy, Malay K.
2018-06-01
Generalized uncertainty relation that carries the imprint of quantum gravity introduces a minimal length scale into the description of space-time. It effectively changes the invariant measure of the phase space through a factor (1 + βp2) - 3 so that the equation of state for an electron gas undergoes a significant modification from the ideal case. It has been shown in the literature (Rashidi 2016) that the ideal Chandrasekhar limit ceases to exist when the modified equation of state due to the generalized uncertainty is taken into account. To assess the situation in a more complete fashion, we analyze in detail the mass-radius relation of Newtonian white dwarfs whose hydrostatic equilibria are governed by the equation of state of the degenerate relativistic electron gas subjected to the generalized uncertainty principle. As the constraint of minimal length imposes a severe restriction on the availability of high momentum states, it is speculated that the central Fermi momentum cannot have values arbitrarily higher than pmax ∼β - 1 / 2. When this restriction is imposed, it is found that the system approaches limiting mass values higher than the Chandrasekhar mass upon decreasing the parameter β to a value given by a legitimate upper bound. Instead, when the more realistic restriction due to inverse β-decay is considered, it is found that the mass and radius approach the values 1.4518 M⊙ and 601.18 km near the legitimate upper bound for the parameter β.
To the generalization of experimental data on heat and mass transfer in evaporation and condensation
International Nuclear Information System (INIS)
Berman, L.D.
1980-01-01
Similarity equations for heat-and-mass transfer in binary gas or steam-gas layers in the processes of liquid evaporation, condensation and desublimation of vapours, desorption and absorption and porous body cooling are considered. It is accepted that steam-gas components obey to the equation of ideal gas state and that evaporation and condensation condititons permit to neglect the influence of compressability of gas (steam-gas) mixture, non-isothermality of boundary layer and interphase kinetic resistance to mass transfer onto the interfaces. It is concluded that the results of considered experimental and theoretical investigations of the above processes are in a satisfactory agreement and show insignificance of the effect of hydrodynamic conditions determining the regime of main steam-gas mixture flow on relative heat-and-mass transfer coefficients. According to the theoretical calculation results with increase of the factor of M steam-gas mixture non-uniformity mass transfer intensity in evaporation decreases, while in condensation it grows, but M effect on the mass transfer coefficient is rather small and sowhat increases in the case of a turbulent boundary layer evaporation. In condensation it is less than in evaporation
Mass transfer with chemical reaction in multiphase systems
International Nuclear Information System (INIS)
Alper, E.
1983-01-01
These volumes deal with the phenomenon of 'mass transfer with chemical reaction' which is of industrial, biological and physiological importance. In process engineering, it is encountered both in separation processes and in reaction engineering and both aspects are covered here in four sections: introduction; gas-liquid system; liquid-liquid system; and gas-liquid-solid system
Intensification of mass transfer in wet textile processes by power ultrasound
Moholkar, V.S.; Nierstrasz, Vincent; Warmoeskerken, Marinus
2003-01-01
In industrial textile pre-treatment and finishing processes, mass transfer and mass transport are often rate-limiting. As a result, these processes require a relatively long residence time, large amounts of water and chemicals, and are also energy-consuming. In most of these processes, diffusion and
Energy Technology Data Exchange (ETDEWEB)
He, Zhixia; Zhang, Liang; Saha, Kaushik; Som, Sibendu; Duan, Lian; Wang, Qian
2017-12-01
The super high fuel injection pressure and micro size of nozzle orifice has been an important development trend for the fuel injection system. Accordingly, cavitation transient process, fuel compressibility, amount of noncondensable gas in the fuel and cavitation erosion have attracted more attention. Based on the fact of cavitation in itself is a kind of thermodynamic phase change process, this paper takes the perspective of the cavitation phase change mass transfer process to analyze above mentioned phenomenon. The two-phase cavitating turbulent flow simulations with VOF approach coupled with HRM cavitation model and U-RANS of standard k-ε turbulence model were performed for investigations of cavitation phase change mass transfer process. It is concluded the mass transfer time scale coefficient in the Homogenous Relaxation Model (HRM) representing mass transfer rate should tend to be as small as possible in a condition that ensured the solver stable. At very fast mass transfer rate, the phase change occurs at very thin interface between liquid and vapor phase and condensation occurs more focused and then will contribute predictably to a more serious cavitation erosion. Both the initial non-condensable gas in fuel and the fuel compressibility can accelerate the cavitation mass transfer process.
Flow and mass transfer downstream of an orifice under flow accelerated corrosion conditions
International Nuclear Information System (INIS)
Ahmed, Wael H.; Bello, Mufatiu M.; El Nakla, Meamer; Al Sarkhi, Abdelsalam
2012-01-01
Highlights: ► Mass transfer downstream of orifices was numerically and experimentally investigated. ► The surface wear pattern is measured and used to validate the present numerical results. ► The maximum mass transfer coefficient found to occur at approximately 2–3 pipe diameters downstream of the orifice. ► The FAC wear rates were correlated with the turbulence kinetic energy and wall mass transfer in terms of Sherwood number. ► The current study offered very useful information for FAC engineers for better preparation of nuclear plant inspection scope. - Abstract: Local flow parameters play an important role in characterizing flow accelerated corrosion (FAC) downstream of sudden area change in power plant piping systems. Accurate prediction of the highest FAC wear rate locations enables the mitigation of sudden and catastrophic failures, and the improvement of the plant capacity factor. The objective of the present study is to evaluate the effect of the local flow and mass transfer parameters on flow accelerated corrosion downstream of an orifice. In the present study, orifice to pipe diameter ratios of 0.25, 0.5 and 0.74 were investigated numerically by solving the continuity and momentum equations at Reynolds number of Re = 20,000. Laboratory experiments, using test sections made of hydrocal (CaSO 4 ·½H 2 O) were carried out in order to determine the surface wear pattern and validate the present numerical results. The numerical results were compared to the plants data as well as to the present experiments. The maximum mass transfer coefficient found to occur at approximately 2–3 pipe diameters downstream of the orifice. This location was also found to correspond to the location of elevated turbulent kinetic energy generated within the flow separation vortices downstream of the orifice. The FAC wear rates were correlated with the turbulence kinetic energy and wall mass transfer in terms of Sherwood number. The current study found to offer very
Bibliography on augmentation of convective heat and mass transfer-II
Energy Technology Data Exchange (ETDEWEB)
Bergles, A.E.; Nirmalan, V.; Junkhan, G.H.; Webb, R.L.
1983-12-01
Heat transfer augmentation has developed into a major specialty area in heat transfer research and development. This report presents and updated bibliography of world literature on augmentation. The literature is classified into passive augmentation techniques, which require no external power, and active techniques, which do require external power. The fifteen techniques are grouped in terms of their applications to the various modes of heat transfer. Mass transfer is included for completeness. Key words are included with each citation for technique/mode identification. The total number of publications cited is 3045, including 135 surveys of various techniques and 86 papers on performance evaluation of passive techniques. Patents are not included, as they are the subject of a separate bibliographic report.
Heat and mass transfer during baking: product quality aspects
Asselman, A.; Straten, van G.; Hadiyanto, H.; Boom, R.M.; Esveld, D.C.; Boxtel, van A.J.B.
2005-01-01
Abstract Most food product qualities are developed during heating processes. Therefore the internal heating and mass transfer of water are important aspects in food processing. Heating of food products is mostly induced by convection heating. However, the number applications of convective heating in
Kinetics and mass transfer phenomena in anaerobic granular sludge
Gonzalez-Gil, G.; Seghezzo, L.; Lettinga, G.; Kleerebezem, R.
2001-01-01
The kinetic properties of acetate-degrading methanogenic granular sludge of different mean diameters were assessed at different up-flow velocities (Vup). Using this approach, the influence of internal and external mass transfer could be estimated. First, the apparent Monod constant (KS) for each
Directory of Open Access Journals (Sweden)
Zhixian Huang
Full Text Available Abstract To investigate the mass transfer behavior of a liquid-liquid system with high density difference (∆ρ≈500 kg/m3, single drop experiments were performed by using the ternary chloroform-ethanol-water system. The mass transfer direction was from the dispersed phase to the continuous phase, while the aqueous phase was dispersed in chloroform to generate drops. The influences of drop diameter, initial solute concentration and temperature on the mass transfer were investigated. The effects of the drop diameter and initial solute concentration on interfacial instability of droplets hanging in the continuous phase were also observed. For the purpose of correlation, a mass transfer enhancement factor F was introduced and then correlated as a function of dimensionless variables. The modified correlation from the mass transfer coefficient model was found to fit well with the experimental values.
Measurements of Critical Heat Flux using Mass Transfer System
Energy Technology Data Exchange (ETDEWEB)
Hong, Seung Hyun; Chung Bum Jin [Kyunghee University, Yongin (Korea, Republic of)
2016-05-15
In a severe accident, the reactor vessel is heated by the decay heat from core melts and the outer surface of reactor vessel is cooled by the natural convection of water pool. When the heat flux increases, boiling will start. Further increase of the heat flux may result in the CHF, which is generated by the bubble combinations. The CHF means that the reactor vessel was separated with coolant and wall temperature is raised rapidly. It may damage the reactor vessel. Also the CHF indicates the maximum cooling capability of the system. Therefore, the CHF has been used as a criterion for the regulatory and licensing. Mechanism of hydrogen vapor bubbles generated and combined can be simulated water bubbles mechanism. And also the both heat and mass transfer mechanism of CHF can be identified in the same methods. Therefore, the CHF phenomena can be simulated enough by mass transfer.
Mass transfer analysis for terephthalic acid biodegradation by ...
African Journals Online (AJOL)
Biodegradation of terephthalic acid (TA) by polyvinyl alcohol (PVA)-alginate immobilized Pseudomonas sp. was carried out in a packed-bed reactor. The effect of inlet TA concentration on biodegradation was investigated at 30°C, pH 7 and flow rate of 20 ml/min. The effects of flow rate on mass transfer and biodegradation ...
Marin, Pricila; Borba, Carlos Eduardo; Módenes, Aparecido Nivaldo; Espinoza-Quiñones, Fernando R; de Oliveira, Silvia Priscila Dias; Kroumov, Alexander Dimitrov
2014-01-01
Reactive blue 5G dye removal in a fixed-bed column packed with Dowex Optipore SD-2 adsorbent was modelled. Three mathematical models were tested in order to determine the limiting step of the mass transfer of the dye adsorption process onto the adsorbent. The mass transfer resistance was considered to be a criterion for the determination of the difference between models. The models contained information about the external, internal, or surface adsorption limiting step. In the model development procedure, two hypotheses were applied to describe the internal mass transfer resistance. First, the mass transfer coefficient constant was considered. Second, the mass transfer coefficient was considered as a function of the dye concentration in the adsorbent. The experimental breakthrough curves were obtained for different particle diameters of the adsorbent, flow rates, and feed dye concentrations in order to evaluate the predictive power of the models. The values of the mass transfer parameters of the mathematical models were estimated by using the downhill simplex optimization method. The results showed that the model that considered internal resistance with a variable mass transfer coefficient was more flexible than the other ones and this model described the dynamics of the adsorption process of the dye in the fixed-bed column better. Hence, this model can be used for optimization and column design purposes for the investigated systems and similar ones.
International Nuclear Information System (INIS)
Yoo, Seong Yeon; Han, Kyu Hyun; Kim, Jin Hyuck
2010-01-01
In closed wet cooling towers, the heat transfer between the air and external tube surfaces can be composed of the sensible heat transfer and the latent heat transfer. The heat transfer coefficient can be obtained from the equation for external heat transfer of tube banks. According to experimental data, the mass transfer coefficient was affected by the air velocity and spray water flow rate. This study provides the correlation equation for mass transfer coefficient based on the analogy of the heat and mass transfer and the experimental data. The results from this correlation equation showed fairly good agreement with experimental data. The cooling capacity and thermal efficiency of the closed wet cooling tower were calculated from the correlation equation to analyze the performance of heat exchanger for the tower
Mass transfer controlled reactions in packed beds at low Reynolds numbers
Energy Technology Data Exchange (ETDEWEB)
Fedkiw, P.S.
1978-12-01
The a priori prediction and correlation of mass-transfer rates in transport limited, packed-bed reactors at low Reynolds numbers is examined. The solutions to the governing equations for a flow-through porous electrode reactor indicate that these devices must operate at a low space velocity to suppress a large ohmic potential drop. Packed-bed data for the mass-transfer rate at such low Reynolds numbers were examined and found to be sparse, especially in liquid systems. Prior models to simulate the solid-void structure in a bed are reviewed. Here the bed was envisioned as an array of sinusoidal periodically constricted tubes (PCT). Use of this model has not appeared in the literature. The velocity field in such a tube should be a good approximation to the converging-diverging character of the velocity field in an actual bed. The creeping flow velocity profiles were calculated. These results were used in the convective-diffusion equation to find mass transfer rates at high Peclet number for both deep and shallow beds, for low Peclet numbers in a deep bed. All calculations assumed that the reactant concentration at the tube surface is zero. Mass-transfer data were experimentally taken in a transport controlled, flow-through porous electrode to test the theoretical calculations and to provide data resently unavailable for deeper beds. It was found that the sinusoidal PCT model could not fit the data of this work or that available in the literature. However, all data could be adequately described by a model which incorporates a channelingeffect. The bed was successfully modeled as an array of dual sized straight tubes.
The influence of pH on gas-liquid mass transfer in non-Newtonian fluids
Directory of Open Access Journals (Sweden)
Li Shaobai
2017-01-01
Full Text Available In this study, the effect of pH on the mass transfer of oxygen bubble swarms in non-Newtonian fluids was experimentally studied. The volumetric liquid side mass transfer coefficient (kLa, liquid side mass transfer coefficient (kL, and specific interfacial area (a were investigated. The pH was regulated by the addition of hydrochloric acid and sodium hydroxide (NaOH. It was found that the kLa increased with the gas flow rate increasing and decreased with the apparent viscosity of the liquid increasing. In the case of pH 7 was attributed to the decomposition of the Xanthan molecular structure by the hydroxyl of NaOH.
Kreulen, H.; Versteeg, G.F.; Swaaij, W.P.M. van
1993-01-01
Absorption determined by mass transfer in the liquid is described well with the Graetz-Lévèque equation adapted from heat transfer. The influence of a chemical reaction on the mass transfer was simulated with a numerical model and tested on the absorption of CO2 in a hydroxide solution. Absorption
Behaviour of and mass transfer at gas-evolving electrodes
Janssen, L.J.J.
1989-01-01
A completes set of models for the mass transfer of indicator ions to gas-evolving electrodes with different behaviour of bubbles is described theoretically. Sliding bubbles, rising detached single bubbles, jumping detached coalescence bubbles and ensembles of these types of bubbles are taken into
Orgill, James J; Atiyeh, Hasan K; Devarapalli, Mamatha; Phillips, John R; Lewis, Randy S; Huhnke, Raymond L
2013-04-01
Trickle-bed reactor (TBR), hollow fiber membrane reactor (HFR) and stirred tank reactor (STR) can be used in fermentation of sparingly soluble gasses such as CO and H2 to produce biofuels and bio-based chemicals. Gas fermenting reactors must provide high mass transfer capabilities that match the kinetic requirements of the microorganisms used. The present study compared the volumetric mass transfer coefficient (K(tot)A/V(L)) of three reactor types; the TBR with 3 mm and 6 mm beads, five different modules of HFRs, and the STR. The analysis was performed using O2 as the gaseous mass transfer agent. The non-porous polydimethylsiloxane (PDMS) HFR provided the highest K(tot)A/V(L) (1062 h(-1)), followed by the TBR with 6mm beads (421 h(-1)), and then the STR (114 h(-1)). The mass transfer characteristics in each reactor were affected by agitation speed, and gas and liquid flow rates. Furthermore, issues regarding the comparison of mass transfer coefficients are discussed. Copyright © 2013 Elsevier Ltd. All rights reserved.
Li, Cun-Yu; Wu, Xin; Gu, Jia-Mei; Li, Hong-Yang; Peng, Guo-Ping
2018-04-01
Based on the molecular sieving and solution-diffusion effect in nanofiltration separation, the correlation between initial concentration and mass transfer coefficient of three typical phenolic acids from Salvia miltiorrhiza was fitted to analyze the relationship among mass transfer coefficient, molecular weight and concentration. The experiment showed a linear relationship between operation pressure and membrane flux. Meanwhile, the membrane flux was gradually decayed with the increase of solute concentration. On the basis of the molecular sieving and solution-diffusion effect, the mass transfer coefficient and initial concentration of three phenolic acids showed a power function relationship, and the regression coefficients were all greater than 0.9. The mass transfer coefficient and molecular weight of three phenolic acids were negatively correlated with each other, and the order from high to low is protocatechualdehyde >rosmarinic acid> salvianolic acid B. The separation mechanism of nanofiltration for phenolic acids was further clarified through the analysis of the correlation of molecular weight and nanofiltration mass transfer coefficient. The findings provide references for nanofiltration separation, especially for traditional Chinese medicine with phenolic acids. Copyright© by the Chinese Pharmaceutical Association.
Heat and Mass Transfer of Vacuum Cooling for Porous Foods-Parameter Sensitivity Analysis
Directory of Open Access Journals (Sweden)
Zhijun Zhang
2014-01-01
Full Text Available Based on the theory of heat and mass transfer, a coupled model for the porous food vacuum cooling process is constructed. Sensitivity analyses of the process to food density, thermal conductivity, specific heat, latent heat of evaporation, diameter of pores, mass transfer coefficient, viscosity of gas, and porosity were examined. The simulation results show that the food density would affect the vacuum cooling process but not the vacuum cooling end temperature. The surface temperature of food was slightly affected and the core temperature is not affected by the changed thermal conductivity. The core temperature and surface temperature are affected by the changed specific heat. The core temperature and surface temperature are affected by the changed latent heat of evaporation. The core temperature is affected by the diameter of pores. But the surface temperature is not affected obviously. The core temperature and surface temperature are not affected by the changed gas viscosity. The parameter sensitivity of mass transfer coefficient is obvious. The core temperature and surface temperature are affected by the changed mass transfer coefficient. In all the simulations, the end temperature of core and surface is not affected. The vacuum cooling process of porous medium is a process controlled by outside process.
Directory of Open Access Journals (Sweden)
Eric Monflier
2012-11-01
Full Text Available The replacement of hazardous solvents and the utilization of catalytic processes are two key points of the green chemistry movement, so aqueous organometallic catalytic processes are of great interest in this context. Nevertheless, these processes require not only the use of water-soluble ligands such as phosphanes to solubilise the transition metals in water, but also the use of mass transfer agents to increase the solubility of organic substrates in water. In this context, phosphanes based on a cyclodextrin skeleton are an interesting alternative since these compounds can simultaneously act as mass transfer agents and as coordinating species towards transition metals. For twenty years, various cyclodextrin-functionalized phosphanes have been described in the literature. Nevertheless, while their coordinating properties towards transition metals and their catalytic properties were fully detailed, their mass transfer agent properties were much less discussed. As these mass transfer agent properties are directly linked to the availability of the cyclodextrin cavity, the aim of this review is to demonstrate that the nature of the reaction solvent and the nature of the linker between cyclodextrin and phosphorous moieties can deeply influence the recognition properties. In addition, the impact on the catalytic activity will be also discussed.
International Nuclear Information System (INIS)
Bai, Peng; Fan, Kaigong; Guo, Xianghai; Zhang, Haocui
2016-01-01
Highlights: • We propose a non-equilibrium mass transfer absorption model instead of a distillation equilibrium model to calculate boron isotopes separation. • We apply the model to calculate the needed column height to meet prescribed separation requirements. - Abstract: To interpret the phenomenon of chemical exchange in boron isotopes separation accurately, the process is specified as an absorption–reaction–desorption hybrid process instead of a distillation equilibrium model, the non-equilibrium mass transfer absorption model is put forward and a mass transfer enhancement factor E is introduced to find the packing height needed to meet the specified separation requirements with MATLAB.
Heat and mass transfer and hydrodynamics in two-phase flows in nuclear power plants
International Nuclear Information System (INIS)
Styrikovich, M.A.; Polonskii, V.S.; Tsiklauri, G.V.
1986-01-01
This book examines nuclear power plant equipment from the point of view of heat and mass transfer and the behavior of impurities contained in water and in steam, with reference to real water regimes of nuclear power plants. The transfer processes of equipment are considered. Heat and mass transfer are analyzed in the pre-crisis regions of steam-generating passages with non-permeable surfaces, and in capillary-porous structures. Attention is given to forced convection boiling crises and top post-DNB heat transfer. Data on two-phase hydrodynamics in straight and curved channels are correlated and safety aspects of nuclear power plants are discussed
International Nuclear Information System (INIS)
Neretnieks, Ivars; Liu Longcheng; Moreno, Luis
2010-03-01
Models are presented for solute transport between seeping water in fractured rock and a copper canister embedded in a clay buffer. The migration through an undamaged buffer is by molecular diffusion only as the clay has so low hydraulic conductivity that water flow can be neglected. In the fractures and in any damaged zone seeping water carries the solutes to or from the vicinity of the buffer in the deposition hole. During the time the water passes the deposition hole molecular diffusion aids in the mass transfer of solutes between the water/buffer interface and the water at some distance from the interface. The residence time of the water and the contact area between the water and the buffer determine the rate of mass transfer between water and buffer. Simple analytical solutions are presented for the mass transfer in the seeping water. For complex migration geometries simplifying assumptions are made that allow analytical solutions to be obtained. The influence of variable apertures on the mass transfer is discussed and is shown to be moderate. The impact of damage to the rock around the deposition hole by spalling and by the presence of a cemented and fractured buffer is also explored. These phenomena lead to an increase of mass transfer between water and buffer. The overall rate of mass transfer between the bulk of the water and the canister is proportional to the overall concentration difference and inversely proportional to the sum of the mass transfer resistances. For visualization purposes the concept of equivalent flowrate is introduced. This entity can be thought as of the flowrate of water that will be depleted of its solute during the water passage past the deposition hole. The equivalent flowrate is also used to assess the release rate of radionuclides from a damaged canister. Examples are presented to illustrate how various factors influence the rate of mass transfer
Mass Transfer Coefficients and Bubble Sizes in Oxidative Ladle Refining of Silicon
Bjørnstad, Erlend Lunnan
2016-01-01
The mass transfer of [Al] and [Ca] between three synthetic SiO_{2}-CaO-Al_{2}O_{3} slags, and 8N silicon, has been investigated to find the overall mass transfer coefficient k_{i,t} for the individual species. Samples were kept at 1873K for 5, 10, 20, 30 and 180min before quenching. The metal phase was later analyzed by ICP-MS to view how the concentrations of impurities change with respect to time. This work then compares these results to industrial data gathered from ladles used for oxidati...
Ogorzalek Loo, Rachel R.; Mitchell, Charles; Stevenson, Tracy I.; Loo, Joseph A.; Andrews, Philip C.
1997-12-01
Diffusive transfer was examined as a blotting method to transfer proteins from polyacrylamide gels to membranes for ultraviolet matrix-assisted laser desorption ionization (MALDI) mass spectrometry. The method is well-suited for transfers from isoelectric focusing (IEF) gels. Spectra have been obtained for 11 pmol of 66 kDa albumin loaded onto an IEF gel and subsequently blotted to polyethylene. Similarly, masses of intact carbonic anhydrase and hemoglobin were obtained from 14 and 20 pmol loadings. This methodology is also compatible with blotting high molecular weight proteins, as seen for 6 pmol of the 150 kDa monoclonal antibody anti-[beta]-galactosidase transferred to Goretex. Polypropylene, Teflon, Nafion and polyvinylidene difluoride (PVDF) also produced good spectra following diffusive transfer. Only analysis from PVDF required that the membrane be kept wet prior to application of matrix. Considerations in mass accuracy for analysis from large-area membranes with continuous extraction and delayed extraction were explored, as were remedies for surface charging. Vapor phase CNBr cleavage was applied to membrane-bound samples for peptide mapping.
International Nuclear Information System (INIS)
Croitoru, C.; Pop, F.; Titescu, Gh.; Culcer, M.; Iliescu, M.; Stefanescu, I.; Trancota, D.; Peculea, M.
2002-01-01
The paper presents theoretical and experimental data concerning mass and heat transfer on B7 ordered packing, at deuterium separation by distillation. The first section of the paper is dedicated to the mass transfer study of hydrogen distillation, while the second section deals with mass and heat transfer in water distillation. A mathematical model was worked out and compared with experimental data, obtained from two laboratory distillation plants for deuterium separation. From the first plant experimental data concerning B7 ordered packing efficiency of hydrogen cryogenic distillation at 250 deg. C level were obtained. Data concerning mass and heat transfer on the same packing in deuterium separation by water vacuum distillation at 60 deg. C level were obtained in the second plant. HUT values, mass and heat transfer coefficients both theoretically evaluated and experimentally determined were found to be comparable with those obtained from chemical industry separation processes. The fact justifies the use of multi-tubular column model for description of transfer processes in distillation columns equipped with B7 structured packing. (authors)
International Nuclear Information System (INIS)
Ma, Shuangchen; Chen, Gongda; Zhu, Sijie; Han, Tingting; Yu, Weijing
2016-01-01
Highlights: • Mass transfer coefficient models of ammonia escape were built. • Influences of temperature, inlet CO 2 and ammonia concentration were studied. • Mass transfer coefficients of ammonia escape and CO 2 absorption were obtained. • Studies can provide the basic data as a reference guideline for process application. - Abstract: The mass transfer of CO 2 capture using ammonia solution in the bubbling reactor was studied; according to double film theory, the mass transfer coefficient models and interface area model were built. Through our experiments, the overall volumetric mass transfer coefficients were obtained, while the interface areas in unit volume were estimated. The volumetric mass transfer coefficients of ammonia escaping during the experiment were 1.39 × 10 −5 –4.34 × 10 −5 mol/(m 3 s Pa), and the volumetric mass transfer coefficients of CO 2 absorption were 2.86 × 10 −5 –17.9 × 10 −5 mol/(m 3 s Pa). The estimated interface area of unit volume in the bubbling reactor ranged from 75.19 to 256.41 m 2 /m 3 , making the bubbling reactor a viable choice to obtain higher mass transfer performance than the packed tower or spraying tower.
Zhou, Quanlin; Oldenburg, Curtis M.; Rutqvist, Jonny; Birkholzer, Jens T.
2017-11-01
There are two types of analytical solutions of temperature/concentration in and heat/mass transfer through boundaries of regularly shaped 1-D, 2-D, and 3-D blocks. These infinite-series solutions with either error functions or exponentials exhibit highly irregular but complementary convergence at different dimensionless times, td. In this paper, approximate solutions were developed by combining the error-function-series solutions for early times and the exponential-series solutions for late times and by using time partitioning at the switchover time, td0. The combined solutions contain either the leading term of both series for normal-accuracy approximations (with less than 0.003 relative error) or the first two terms for high-accuracy approximations (with less than 10-7 relative error) for 1-D isotropic (spheres, cylinders, slabs) and 2-D/3-D rectangular blocks (squares, cubes, rectangles, and rectangular parallelepipeds). This rapid and uniform convergence for rectangular blocks was achieved by employing the same time partitioning with individual dimensionless times for different directions and the product of their combined 1-D slab solutions. The switchover dimensionless time was determined to minimize the maximum approximation errors. Furthermore, the analytical solutions of first-order heat/mass flux for 2-D/3-D rectangular blocks were derived for normal-accuracy approximations. These flux equations contain the early-time solution with a three-term polynomial in √td and the late-time solution with the limited-term exponentials for rectangular blocks. The heat/mass flux equations and the combined temperature/concentration solutions form the ultimate kernel for fast simulations of multirate and multidimensional heat/mass transfer in porous/fractured media with millions of low-permeability blocks of varying shapes and sizes.
Heat and mass transfer in the unsteady hydromagnetic free ...
African Journals Online (AJOL)
Heat and mass transfer in the unsteady hydromagnetic free-convection flow in a rotating binary fluid I. ... By imposing a time dependent perturbation on the constant plate temperature and concentration and assuming a differential approximation for the radiative flux, the coupled non linear problem is solved for the ...
Dynamic modeling of fixed-bed adsorption of flue gas using a variable mass transfer model
International Nuclear Information System (INIS)
Park, Jehun; Lee, Jae W.
2016-01-01
This study introduces a dynamic mass transfer model for the fixed-bed adsorption of a flue gas. The derivation of the variable mass transfer coefficient is based on pore diffusion theory and it is a function of effective porosity, temperature, and pressure as well as the adsorbate composition. Adsorption experiments were done at four different pressures (1.8, 5, 10 and 20 bars) and three different temperatures (30, 50 and 70 .deg. C) with zeolite 13X as the adsorbent. To explain the equilibrium adsorption capacity, the Langmuir-Freundlich isotherm model was adopted, and the parameters of the isotherm equation were fitted to the experimental data for a wide range of pressures and temperatures. Then, dynamic simulations were performed using the system equations for material and energy balance with the equilibrium adsorption isotherm data. The optimal mass transfer and heat transfer coefficients were determined after iterative calculations. As a result, the dynamic variable mass transfer model can estimate the adsorption rate for a wide range of concentrations and precisely simulate the fixed-bed adsorption process of a flue gas mixture of carbon dioxide and nitrogen.
International Nuclear Information System (INIS)
Balasubramonian, S.; Sivakumar, D.; Kumar, Shekhar; Kamachi Mudali, U.
2014-01-01
The rotating disc contactor is the widely used liquid-liquid extraction equipment for its high throughput and efficiency. In this work mass transfer performance of the miniature RDC column for the 30% TBP/nitric acid biphasic system was studied in terms of the operating variables such as rotor speed and flow rate of the aqueous and organic phase. The RDC column used in the experiments was shown. The column shell is made up of thick glass having diameter of 10.5 cm and height 100 cm. The rotor diameter is 5.3 cm and stator opening diameter is 6.3 cm. Totally 25 number of rotor discs were welded in the rotating shaft. This shaft was aligned in such a way that each rotor was placed in the centre of the compartment formed in between the two stator rings. The experiments were carried out to study the effect of rotor speed and superficial velocity of the dispersed and continuous phase on mass transfer efficiency. The organic solvent was made as the continuous phase and O/A ratio was set as 4 in both the continuous to dispersed phase(c-d) and dispersed to continuous phase (d-c) mass transfer experiments. The Number of Transfer Units (NTU) was estimated based on the solvent phase. The graphical representation of NTU was shown. The NTU value was observed as 4 and 3 respectively for extraction and stripping at the combined through put of 60 L/h and the rotor speed of 1000 rpm. This corresponds to the Height of Transfer Unit (HTU) value of 15 cm and 20 cm respectively for d-c and c-d mass transfer. The estimated overall mass transfer coefficient was increasing with rotor speed and superficial velocity of the liquid phases. The overall mass transfer coefficient also increases with increase in hold up
Heat and mass transfer in porous cavity: Assisting flow
Energy Technology Data Exchange (ETDEWEB)
Badruddin, Irfan Anjum [Dept. of Mechanical Engineering, University of Malaya, Kuala Lumpur, 50603 (Malaysia); Quadir, G. A. [School of Mechatronic Engineering, University Malaysia Perlis, Pauh Putra, 02600 Arau, Perlis (Malaysia)
2016-06-08
In this paper, investigation of heat and mass transfer in a porous cavity is carried out. The governing partial differential equations are non-dimensionalised and solved using finite element method. The left vertical surface of the cavity is maintained at constant temperature and concentration which are higher than the ambient temperature and concentration applied at right vertical surface. The top and bottom walls of the cavity are adiabatic. Heat transfer is assumed to take place by natural convection and radiation. The investigation is carried out for assisting flow when buoyancy and gravity force act in same direction.
Calculation of Post-Closure Natural Convection Heat and Mass Transfer in Yucca Mountain Drifts
International Nuclear Information System (INIS)
Webb, S.; Itamura, M.
2004-01-01
Natural convection heat and mass transfer under post-closure conditions has been calculated for Yucca Mountain drifts using the computational fluid dynamics (CFD) code FLUENT. Calculations have been performed for 300, 1000, 3000, and 10,000 years after repository closure. Effective dispersion coefficients that can be used to calculate mass transfer in the drift have been evaluated as a function of time and boundary temperature tilt
The mass transfer dynamics of gaseous methyl-iodide adsorption by silver-exchanged sodium mordenite
International Nuclear Information System (INIS)
Jubin, R.T.
1994-12-01
The adsorption of methyl iodide onto hydrogen-reduced silver-exchange mordenite was studied. The removal of organic iodides from off-gas streams is an important step in controlling the release of radioactive iodine to the environment during the treatment of radioactive wastes or the processing of some irradiated materials. Nine well accepted mass transfer models were evaluated for their ability to adequately explain the observed CH 3 I uptake behavior onto the Ag-Z. Linear and multidimensional regression techniques were utilized in the estimation of the diffusion constants and other model parameters which then permitted the selection of an appropriate mass transfer model. To date, only bulk loading data exist for the adsorption of CH 3 I onto Ag-Z. Hence this is believed to be the first study to quantify the controlling mass transfer mechanisms of this process. It can be concluded from the analysis of the experimental data obtained by the single-pellet type experiments and for the process conditions used in this study that the overall mass transfer rate associated with the adsorption of CH 3 I onto Ag-Z is affected by both micropore and macropore diffusion. The macropore diffusion rate was significantly faster than the micropore diffusion, resulting in a two-step adsorption behavior which was adequately modeled by a bimodal pore distribution model. The micropore diffusivity was determined to be on the order of 2 x 10 -14 cm 2 /s. The system was also shown to be isothermal under all conditions of this study. Two other conclusions were also obtained. First, the gas film resistance to mass transfer for the 1/16 and 1/8-in.-diam Ag-Z pellets can be ignored under the conditions used in this study. Finally, it was shown that by decreasing the water vapor content of the feed gas, the chemical reaction rate appeared to become the initial rate-limiting factor for the mass transfer. 75 refs
International Nuclear Information System (INIS)
Bhattacharyya, Krishnendu; Layek, G C; Seth, G S
2014-01-01
A mathematical model is presented to study the Soret and Dufour effects on the convective heat and mass transfer in stagnation-point flow of viscous incompressible fluid towards a shrinking surface. Suitable similarity transformations are used to convert the governing partial differential equations into self-similarity ordinary differential equations that are then numerically solved by shooting method. Dual solutions for temperature and concentration are obtained in the presence of Soret and Dufour effects. Graphical representations of the heat and mass transfer coefficients, the dimensionless thermal and solute profiles for various values of Prandtl number, Lewis number, Soret number and Dufour number are demonstrated. With Soret number the mass transfer coefficient which is related to mass transfer rate increases for both solutions and the heat transfer coefficient (related to heat transfer rate) for both solutions becomes larger with Dufour number. The Prandtl number causes reduction in heat and the mass transfer coefficients and similarly with the Lewis number mass transfer coefficient decreases. Also, double crossing over is found in dual dimensionless temperature profiles for increasing Soret number and in dual dimensionless concentration profiles for the increase in Dufour number. Due to the larger values of Dufour number the thermal boundary layer increases and for Prandtl number increment it decreases; whereas, the solute boundary layer thickness reduces with increasing values of Prandtl number and Lewis number. (paper)
MASS TRANSFER COEFFICIENTS FOR A NON-NEWTONIAN FLUID AND WATER WITH AND WITHOUT ANTI-FOAM AGENTS
Energy Technology Data Exchange (ETDEWEB)
Leishear, R.
2009-09-09
Mass transfer rates were measured in a large scale system, which consisted of an 8.4 meter tall by 0.76 meter diameter column containing one of three fluids: water with an anti-foam agent, water without an anti-foam agent, and AZ101 simulant, which simulated a non-Newtonian nuclear waste. The testing contributed to the evaluation of large scale mass transfer of hydrogen in nuclear waste tanks. Due to its radioactivity, the waste was chemically simulated, and due to flammability concerns oxygen was used in lieu of hydrogen. Different liquids were used to better understand the mass transfer processes, where each of the fluids was saturated with oxygen, and the oxygen was then removed from solution as air bubbled up, or sparged, through the solution from the bottom of the column. Air sparging was supplied by a single tube which was co-axial to the column, the decrease in oxygen concentration was recorded, and oxygen measurements were then used to determine the mass transfer coefficients to describe the rate of oxygen transfer from solution. Superficial, average, sparging velocities of 2, 5, and 10 mm/second were applied to each of the liquids at three different column fill levels, and mass transfer coefficient test results are presented here for combinations of superficial velocities and fluid levels.
MASS TRANSFER COEFFICIENTS FOR A NON-NEWTONIAN FLUID AND WATER WITH AND WITHOUT ANTI-FOAM AGENTS
International Nuclear Information System (INIS)
Leishear, R.
2009-01-01
Mass transfer rates were measured in a large scale system, which consisted of an 8.4 meter tall by 0.76 meter diameter column containing one of three fluids: water with an anti-foam agent, water without an anti-foam agent, and AZ101 simulant, which simulated a non-Newtonian nuclear waste. The testing contributed to the evaluation of large scale mass transfer of hydrogen in nuclear waste tanks. Due to its radioactivity, the waste was chemically simulated, and due to flammability concerns oxygen was used in lieu of hydrogen. Different liquids were used to better understand the mass transfer processes, where each of the fluids was saturated with oxygen, and the oxygen was then removed from solution as air bubbled up, or sparged, through the solution from the bottom of the column. Air sparging was supplied by a single tube which was co-axial to the column, the decrease in oxygen concentration was recorded, and oxygen measurements were then used to determine the mass transfer coefficients to describe the rate of oxygen transfer from solution. Superficial, average, sparging velocities of 2, 5, and 10 mm/second were applied to each of the liquids at three different column fill levels, and mass transfer coefficient test results are presented here for combinations of superficial velocities and fluid levels
Ruth, van S.M.; Floris, V.; Fayoux, S.
2006-01-01
The volatile profiles of 13 infant formulas were evaluated by proton transfer reaction-mass spectrometry (PTR-MS) and gas chromatography¿mass spectrometry (GC¿MS). The infant formulas varied in brand (Aptamil, Cow & Gate, SMA), type (for different infant target groups) and physical form
Mass transfer with complex reversible chemical reactions—I. Single reversible chemical reaction
Versteeg, G.F.; Kuipers, J.A.M.; Beckum, F.P.H. van; Swaaij, W.P.M. van
1989-01-01
An improved numerical technique was used in order to develop an absorption model with which it is possible to calculate rapidly absorption rates for the phenomenon of mass transfer accompanied by a complex reversible chemical reaction. This model can be applied for the calculation of the mass
Energy Technology Data Exchange (ETDEWEB)
Ralph, J C; Bennett, A W [Atomic Energy Research Establishment, Harwell, Oxfordshire (United Kingdom)
1977-01-01
A detailed knowledge is required of the amounts of sodium vapour which may be transported from the hot surface of a fast reactor coolant pool through the cover gas to cooler regions of the structure. Evaporation from the unbounded liquid surfaces of lakes and seas has been studied extensively but the heat and mass transfer mechanisms in gas-vapour mixtures which occur in enclosed spaces have received less attention. Recent work at Harwell has provided a theoretical model from which the heat and mass transfer in idealised plane cavities can be calculated. An experimental study is reported in this paper which seeks to verify the theoretical prediction. Heat and mass transfer measurements have been made on a system in which a heated water pool transfers heat and mass across a gas-filled space to a cooled horizontal cover plate. Several cover gases were used in the experiments and the results show that, provided the partial density of the vapour is low compared with that of the gas, the heat transfer mechanism is that of combined convection and radiation. The enhancement in heat transfer due to the presence of the vapour is broadly consistent with assumption of a direct analogy between heat and mass transfer neglecting condensation in the interspace. The mass transfer measurements, in which water condensing on the cooled roof was measured directly, showed for low roof temperatures an imbalance between the mass and heat transfer. This observation is consistent with the theoretical predictions that heat transfer in the convecting system should be independent of the amount of condensation and 'rain-back' within the cavity. The results of tests with helium showed that convection was entirely suppressed by the presence of the water vapour. This confirms the behaviour predicted for gas-vapour mixtures in which the vapour density is of the same order as the gas density. (author)
International Nuclear Information System (INIS)
Do, Chuong; Hussey, Dennis; Wells, Daniel M.; Epperson, Kenny
2016-01-01
Optimization numerical method was implemented to determine several mass transfer coefficients in a crud-induced power shift risk assessment code. The approach was to utilize a multilevel strategy that targets different model parameters that first changes the major order variables, mass transfer inputs, then calibrates the minor order variables, crud source terms, according to available plant data. In this manner, the mass transfer inputs are effectively simplified as 'dependent' on the crud source terms. Two optimization studies were performed using DAKOTA, a design and analysis toolkit, with the difference between the runs, being the number of model runs using BOA, allowed for adjusting the crud source terms, therefore, reducing the uncertainty with calibration. The result of the first case showed that the current best estimated values for the mass transfer coefficients, which were derived from first principle analysis, can be considered an optimized set. When the run limit of BOA was increased for the second case, an improvement in the prediction was obtained with the results deviating slightly from the best estimated values. (author)
Kim, Ok-Hee; Cho, Yong-Hun; Kang, Soon Hyung; Park, Hee-Young; Kim, Minhyoung; Lim, Ju Wan; Chung, Dong Young; Lee, Myeong Jae; Choe, Heeman; Sung, Yung-Eun
2013-01-01
Three-dimensional, ordered macroporous materials such as inverse opal structures are attractive materials for various applications in electrochemical devices because of the benefits derived from their periodic structures: relatively large surface areas, large voidage, low tortuosity and interconnected macropores. However, a direct application of an inverse opal structure in membrane electrode assemblies has been considered impractical because of the limitations in fabrication routes including an unsuitable substrate. Here we report the demonstration of a single cell that maintains an inverse opal structure entirely within a membrane electrode assembly. Compared with the conventional catalyst slurry, an ink-based assembly, this modified assembly has a robust and integrated configuration of catalyst layers; therefore, the loss of catalyst particles can be minimized. Furthermore, the inverse-opal-structure electrode maintains an effective porosity, an enhanced performance, as well as an improved mass transfer and more effective water management, owing to its morphological advantages.
Gas-liquid mass transfer coefficient of methane in bubble column reactor
International Nuclear Information System (INIS)
Lee, Jaewon; Ha, Kyoung-Su; Lee, Jinwon; Kim, Choongik; Yasin, Muhammad; Park, Shinyoung; Chang, In Seop; Lee, Eun Yeol
2015-01-01
Biological conversion of methane gas has been attracting considerable recent interest. However, methanotropic bioreactor is limited by low solubility of methane gas in aqueous solution. Although a large mass transfer coefficient of methane in water could possibly overcome this limitation, no dissolved methane probe in aqueous environment is commercially available. We have developed a reactor enabling the measurement of aqueous phase methane concentration and mass transfer coefficient (k L a). The feasibility of the new reactor was demonstrated by measuring k L a values as a function of spinning rate of impeller and flow rate of methane gas. Especially, at spinning rate of 300 rpm and flow rate of 3.0 L/min, a large k L a value of 102.9 h -1 was obtained
International Nuclear Information System (INIS)
Xiong Jinbiao; Koshizuka, Seiichi; Sakai, Mikio
2011-01-01
Highlights: → We selected and evaluated five two-equation eddy-viscosity turbulence models for modeling the separated and reattaching flow. → The behavior of the models in the simple flow is not consistent with that in the separated and reattaching flow. → The Abe-Kondoh-Nagano model is the best one among the selected model. → Application of the stress limiter and the Kato-Launder modification in the Abe-Kondoh-Nagano model helps to improve prediction of the peak mass transfer coefficient in the orifice flow. → The value of turbulent Schmidt number is investigated. - Abstract: The prediction of mass transfer rate is one of the key elements for estimation of the flow accelerated corrosion (FAC) rate. Three low Reynolds number (LRN) k-ε models (Lam-Bremhorst (LB), Abe-Kondoh-Nagano (AKN) and Hwang-Lin (HL)), one LRN k-ω (Wilcox, WX) model and the k-ω SST model are tested for the computation of the high Schmidt number mass transfer, especially in the flow through an orifice. The models are tested in the computation of three types of flow: (1) the fully developed pipe flow, (2) the flow over a backward facing step, (3) the flow through an orifice. The HL model shows a good performance in predicting mass transfer in the fully developed pipe flow but fails to give reliable prediction in the flow through an orifice. The WX model and the k-ω SST model underpredict the mass transfer rate in the flow types 1 and 3. The LB model underestimates the mass transfer in the flow type 1, but shows abnormal behavior at the reattaching point in type 3. Synthetically evaluating all the models in all the computed case, the AKN model is the best one; however, the prediction is still not satisfactory. In the evaluation in the flow over a backward facing step shows k-ω SST model shows superior performance. This is interpreted as an implication that the combination of the k-ε model and the stress limiter can improve the model behavior in the recirculation bubble. Both the
Interferometric study on the mass transfer in cryogenic distillation under magnetic field
Bao, S. R.; Zhang, R. P.; Y Rong, Y.; Zhi, X. Q.; Qiu, L. M.
2017-12-01
Cryogenic distillation has long been used for the mass production of industrial gases because of its features of high efficiency, high purity, and capability to produce noble gases. It is of great theoretical and practical significance to explore methods to improve the mass transfer efficiency in cryogenic distillation. The negative correlation between the susceptibility of paramagnetic oxygen and temperature provides a new possibility of comprehensive utilization of boiling point and susceptibility differences in cryogenic distillation. Starting from this concept, we proposed a novel distillation intensifying method by using gradient magnetic field, in which the magnetic forces enhance the transport of the oxygen molecules to the liquid phase in the distillation. In this study, a cryogenic testbed was designed and fabricated to study the diffusion between oxygen and nitrogen under magnetic field. A Mach-Zehnder interferometer was used to visualize the concentration distribution during the diffusion process. The mass transfer characteristics with and without magnetic field, in the chamber filled with the magnetized medium, were systematically studied. The concentration redistribution of oxygen was observed, and the stable stratified diffusion between liquid oxygen and nitrogen was prolonged by the non-uniform magnetic field. The experimental results show that the magnetic field can efficiently influence the mass transfer in cryogenic distillation, which can provide a new mechanism for the optimization of air separation process.
Ghoshal, Subhasis; Pasion, Catherine; Alshafie, Mohammed
2004-04-01
Semi-rigid films or skins form at the interface of crude oil and water as a result of the accumulation of asphaltene and resin fractions when the water-immiscible crude oil is contacted with water for a period of time or "aged". The time varying patterns of area-independent mass transfer coefficients of two compounds, benzene and naphthalene, for dissolution from crude oil and gasoline were determined. Aqueous concentrations of the compounds were measured in the eluent from flow-through reactors, where a nondispersed oil phase and constant oil-water interfacial area were maintained. For Brent Blend crude oil and for gasoline amended with asphaltenes and resins, a rapid decrease in both benzene and naphthalene mass transfer coefficients over the first few days of aging was observed. The mass transfer coefficients of the two target solutes were reduced by up to 80% over 35 d although the equilibrium partition coefficients were unchanged. Aging of gasoline, which has negligible amounts of asphaltene and resin, did not result in a change in the solute mass transfer coefficients. The study demonstrates that formation of crude oil-water interfacial films comprised of asphaltenes and resins contribute to time-dependent decreases in rates of release of environmentally relevant solutes from crude oils and may contribute to the persistence of such solutes at crude oil-contaminated sites. It is estimated that the interfacial film has an extremely low film mass transfer coefficient in the range of 10(-6) cm/min.
International Nuclear Information System (INIS)
LeNeveu, D.M.
1996-03-01
Analytical solutions for transient and steady state diffusive mass transfer rates from a pinhole in a waste container are developed for constant concentration and inventory-limited source conditions. Mass transport in three media are considered, inside the pinhole (medium 2), outside the container (medium 3) and inside the container (medium 1). Simple equations are developed for radionuclide mass transfer rates from a pinhole. It is shown that the medium with the largest mass transfer resistance need only be considered to provide a conservative estimate of mass transfer rates. (author) 11 refs., 3 figs
Chaotic scattering in heavy-ion reactions with mass transfer
International Nuclear Information System (INIS)
Rodriguez Padron, Emilio; Guzman Martinez, Fernando
1998-01-01
The role of the mass transfer in heavy ion collisions is analyzed in the framework of a simple semi phenomenological model searching for chaotic scattering effects. The model couples the relative motion of the ions to a collective degree of freedom. The collective degree of freedom is identified by the mass asymmetry of the system. A Saxon-Woods potential is used for nucleus-nucleus interaction whiles a harmonic potential rules the temporal behaviour of the collective degree of freedom. This model shows chaotic scattering which could be an explanation for certain types of cross-section fluctuations observed in this kind of reactions
Heat-And-Mass Transfer Relationship to Determine Shear Stress in Tubular Membrane Systems
DEFF Research Database (Denmark)
Ratkovich, Nicolas Rios; Nopens, Ingmar
2012-01-01
The main drawback of Membrane Bioreactors (MBRs) is the fouling of the membrane. One way to reduce this fouling is through controlling the hydrodynamics of the two-phase slug flow near the membrane surface. It has been proven in literature that the slug flow pattern has a higher scouring effect...... to remove particulates due to the high shear rates and high mass transfer between the membrane surface and the bulk region. However, to calculate the mass transfer coefficient in an efficient and accurate way is not straightforward. Indeed, for accurate determination, numerous complex experimental...
International Nuclear Information System (INIS)
Sarkar, J.; Bhattacharyya, Souvik
2007-01-01
In the present study, the overall conductance and the overall heat transfer area per unit capacity of refrigeration and heat pump systems have been minimized analytically considering both internal and external irreversibilities with variable temperature (finite capacity) heat reservoirs. Hot and cold side refrigerant temperatures, conductance and heat transfer area ratios have been optimized to attain this goal. The results have been verified with the more elaborate numerical optimization results obtained for ammonia based vapour compression refrigeration and heat pump systems working with variable temperature reservoirs. It is observed that the analytical results for optimum refrigerant temperatures, minimum overall conductance and heat transfer area deviate marginally from the numerically optimized results (within 1%), if one assumes a constant heat rejection temperature. The deviation of minimum overall conductance and heat transfer area is more (about 20%), if one considers both the desuperheating and condensation regions separately. However, in the absence of complex and elaborate numerical models, the simple analytical results obtained here can be used as reasonably accurate preliminary guidelines for optimization of refrigeration and heat pump systems
Mass transfer processes in crystalline aggregates containing a fluid phase
Visser, H.J.M.
1999-01-01
Understanding mass transfer processes in porous crystalline aggregates containing a fluid phase is of major importance for modelling partially molten regions of the Earth's mantle, such as those under mid-ocean spreading ridges. Despite the fact that mid-ocean ridges can be considered the
Mass transfer processes in crystalline aggregates containing a fluid phase
Visser, H.J.M.
1999-01-01
Understanding mass transfer processes in porous crystalline aggregates containing a fluid phase is of major importance for modelling partially molten regions of the Earth's mantle, such as those under mid-ocean spreading ridges. Despite the fact that mid-ocean ridges can be considered the simplest
DEFF Research Database (Denmark)
Nie, Jinzhe; Fang, Lei
2014-01-01
Laboratory experimental studies were conducted to investigate the mass transfer of contaminants through a total heat recovery unit with polymer membranes foils. The studies were conducted in twin climate chambers which simulated outdoor and indoor thermal climates. One manufacturd total heat...... chemical gases were used to simulate air contaminants. The concentrations of dosed contaminants in the supply and exhaust air upstream and downstream of the total heat recovery unit were measured with Multi-Gas Monitor Innova 1316 in real time. Experiment results showed that 5% to 9% of dosed contaminants...... could transfer from exhaust air to supply air through the enthalpy recovery unit. The mass transfer efficiency of contaminants was independent of the hygro-thermal differences between indoor and outdoor climate conditions. The mass transfer ratio of the chemical contaminants in the total heat recovery...
Why a New Code for Novae Evolution and Mass Transfer in Binaries?
Directory of Open Access Journals (Sweden)
G. Shaviv
2015-02-01
Full Text Available One of the most interesting problems in Cataclysmic Variables is the long time scale evolution. This problem appears in long time evolution, which is also very important in the search for the progenitor of SN Ia. The classical approach to overcome this problem in the simulation of novae evolution is to assume: (1 A constant in time, rate of mass transfer. (2 The mass transfer rate that does not vary throughout the life time of the nova, even when many eruptions are considered. Here we show that these assumptions are valid only for a single thermonuclear flash and such a calculation cannot be the basis for extrapolation of the behavior over many flashes. In particular, such calculation cannot be used to predict under what conditions an accreting WD may reach the Chandrasekhar mass and collapse. We report on a new code to attack this problem. The basic idea is to create two parallel processes, one calculating the mass losing star and the other the accreting white dwarf. The two processes communicate continuously with each other and follow the time depended mass loss.
Mass transfer in a geologic environment
International Nuclear Information System (INIS)
Zavoshy, S.J.; Chambre, P.L.; Pigford, T.H.
1984-11-01
A new analytical solution is presented that predicts the rate of dissolution of species from a waste package surrounded by a wet porous medium. By equating the rate of diffusive mass transfer into the porous rock to the rate of liquid-surface chemical reaction, an analytical solution for the time-dependent dissolution rate and the time-dependent concentration of dissolved species at the waste surface is obtained. From these results it is shown that for most of the important species in a package of radioactive waste the surface liquid quickly reaches near-saturation concentrations and the dissolution rate can be predicted by the simpler theory that assumes saturation concentrations in the surface liquid. 26 refs., 3 figs., 1 tab
Gas-liquid mass transfer coefficient of methane in bubble column reactor
Energy Technology Data Exchange (ETDEWEB)
Lee, Jaewon; Ha, Kyoung-Su; Lee, Jinwon; Kim, Choongik [Sogang University, Seoul (Korea, Republic of); Yasin, Muhammad; Park, Shinyoung; Chang, In Seop [Gwangju Institute of Science and Technology (GIST), Gwangju (Korea, Republic of); Lee, Eun Yeol [Kyung Hee University, Yongin (Korea, Republic of)
2015-06-15
Biological conversion of methane gas has been attracting considerable recent interest. However, methanotropic bioreactor is limited by low solubility of methane gas in aqueous solution. Although a large mass transfer coefficient of methane in water could possibly overcome this limitation, no dissolved methane probe in aqueous environment is commercially available. We have developed a reactor enabling the measurement of aqueous phase methane concentration and mass transfer coefficient (k{sub L}a). The feasibility of the new reactor was demonstrated by measuring k{sub L}a values as a function of spinning rate of impeller and flow rate of methane gas. Especially, at spinning rate of 300 rpm and flow rate of 3.0 L/min, a large k{sub L}a value of 102.9 h{sup -1} was obtained.
Three-dimensional Hydrodynamical Simulations of Mass Transfer in Binary Systems by a Free Wind
Energy Technology Data Exchange (ETDEWEB)
Liu, Zheng-Wei; Stancliffe, Richard J.; Abate, Carlo; Matrozis, Elvijs, E-mail: zwliu@ynao.ac.cn [Argelander-Institut für Astronomie, Auf dem Hügel 71, D-53121, Bonn (Germany)
2017-09-10
A large fraction of stars in binary systems are expected to undergo mass and angular momentum exchange at some point in their evolution, which can drastically alter the chemical and dynamical properties and fates of the systems. Interaction by stellar wind is an important process in wide binaries. However, the details of wind mass transfer are still not well understood. We perform three-dimensional hydrodynamical simulations of wind mass transfer in binary systems to explore mass-accretion efficiencies and geometries of mass outflows, for a range of mass ratios from 0.05 to 1.0. In particular, we focus on the case of a free wind, in which some physical mechanism accelerates the expelled wind material balancing the gravity of the mass-losing star with the wind velocity comparable to the orbital velocity of the system. We find that the mass-accretion efficiency and accreted specific angular momentum increase with the mass ratio of the system. For an adiabatic wind, we obtain that the accretion efficiency onto the secondary star varies from about 0.1% to 8% for mass ratios between 0.05 and 1.0.
Study of hydrodynamic and mass transfer parameters in pulsed sieve-plate columns
International Nuclear Information System (INIS)
Safdari, J.
2001-01-01
One of the most important liquid-liquid extractor in industry is pulsed column. The pulsed columns are generally classified into the following categories: 1-Pulsed perforated-plate column. 2- Pulsed packed column. The pulsed plate column is differential contactor with the application of mechanical energy and is used for a diverse range of processes. Probably its best known application has been in the nuclear fuel industry. The pulsed plate column consists of a cylindrical shell with settling zones at the top and the bottom of the column. The liquids are fed continuously to the column (flowing counter-currently) and are removed continuously from opposite ends of the column. In this work using a pilot pulsed plate column and two different chemical systems (toluene/acetone/water and n-butyl acetate/acetone/water) various experiments are carried out. In each experiment direction of mass transfer is from organic phase (dispersed phase) into aqueous phase (continuous phase) and the continuous phase is water. The main objects of this thesis are as follow: a- Investigation of effect of operating parameters on dispersed phase hold up, volumetric overall mass transfer coefficients based on dispersed and continuous phase, extraction efficiency, pressure drop of column and flooding velocities (maximum column capacities). Obtained results in this part show that if the calorimetric flow rate of aqueous phase or pulsation intensity increase, hold up, volumetric overall mass transfer coefficients based on both two phases and extraction efficiency will increase and flooding velocities will decrease. Also results show that if volumetric flow rate of organic phase increase, hold up, volumetric mass transfer coefficients based on both two phases and pressure drop will increase and extraction efficiency and flooding velocities will decrease. b- Investigation of effect of internal circulation inside drops in designing pulsed perforated-plate column
Implementation of a new interfacial mass and energy transfer model in RETRAN-3D
International Nuclear Information System (INIS)
Macian, R.; Cebulh, P.; Coddington, P.; Paulsen, M.
1999-01-01
The RETRAN-3D MOD002.0 best estimate code includes a five-equation flow field model developed to deal with situations in which thermodynamic non-equilibrium phenomena are important. Several applications of this model to depressurization and pressurization transients showed serious convergence problems. An analysis of the causes for the numerical instabilities identified the models for interfacial heat and mass transfer as the source of the problems. A new interfacial mass and energy transfer model has thus been developed and implemented in RETRAN-3D. The heat transfer for each phase is equal to the product of the interfacial area density, a heat transfer coefficient and the temperature difference between the interface at saturation and the bulk temperature of the respective phase. However, in the context of RETRAN-3D, the vapor remains saturated in a two-phase volume, and no vapor heat transfer is thus calculated. The values of interfacial area density and heat transfer coefficient are obtained based on correlations appropriate for different flow regimes. A flow regime map, based on the work of Taitel and Dukler, with void fraction and mixture mass flux as map coordinates, is used to identify the flow regime present in a given volume. The new model has performed well when assessed against data from four experimental facilities covering depressurization, condensation and steady state void distribution. The results also demonstrate the viability of the approach followed to develop the new model for a five-equation based code. (author)
Effect of heat and mass transfer coefficients on the performance of automotive catalytic converters
Energy Technology Data Exchange (ETDEWEB)
Shamim, T. [Michigan Univ., Dept. of Mechanical Engineering, Dearborn, MI (United States)
2003-06-01
This paper numerically investigates the role of heat and mass transfer coefficients on the performance of automotive catalytic converters, which are employed to reduce engine exhaust emissions. The pollutant conversion performance of a converter is influenced by a number of physical and chemical processes that take place in gaseous and solid phases as the exhaust gases flow through the catalyst. A quantitative predictive understanding of these complex catalyst processes involving flow dynamics, heterogeneous surface reactions and heat and mass transport mechanisms is important in improving the converter design. The role of convective transport phenomena becomes important at high temperature when the mass transfer becomes rate-limiting to an increasing extent. The objective of the present study is to elucidate the influence of convective heat and mass transfer coefficients (mechanisms). The mathematical model considers the conservation of mass, momentum and energy in both gaseous and solid phases. In addition to the heterogeneous surface reactions, the model also takes into account the adsorption/desorption of oxygen in the catalyst during non-stoichiometric composition of air/fuel mixtures. The governing equations are solved by an implicit scheme using a successive line under a relaxation method. The converter performance under the transient conditions as simulated by the US Federal Test Procedure (US-FTP) is analysed. (Author)
Effect of Reynolds number on flow and mass transfer characteristics of a 90 degree elbow
Fujisawa, Nobuyuki; Ikarashi, Yuya; Yamagata, Takayuki; Taguchi, Syoichi
2016-11-01
The flow and mass transfer characteristics of a 90 degree elbow was studied experimentally by using the mass transfer measurement by plaster dissolution method, the surface flow visualization by oil film method and stereo PIV measurement. The experiments are carried out in a water tunnel of a circular pipe of 56mm in diameter with a working fluid of water. The Reynolds number was varied from 30000 to 200000. The experimental result indicated the change of the mass transfer coefficient distribution in the elbow with increasing the Reynolds number. This phenomenon is further examined by the surface flow visualization and measurement of secondary flow pattern in the elbow, and the results showed the suggested change of the secondary flow pattern in the elbow with increasing the Reynolds numbers.
Heat and mass transfer and hydrodynamics in swirling flows (review)
Leont'ev, A. I.; Kuzma-Kichta, Yu. A.; Popov, I. A.
2017-02-01
Research results of Russian and foreign scientists of heat and mass transfer in whirling flows, swirling effect, superficial vortex generators, thermodynamics and hydrodynamics at micro- and nanoscales, burning at swirl of the flow, and technologies and apparatuses with the use of whirling currents for industry and power generation were presented and discussed at the "Heat and Mass Transfer in Whirling Currents" 5th International Conference. The choice of rational forms of the equipment flow parts when using whirling and swirling flows to increase efficiency of the heat-power equipment and of flow regimes and burning on the basis of deep study of the flow and heat transfer local parameters was set as the main research prospect. In this regard, there is noticeable progress in research methods of whirling and swirling flows. The number of computational treatments of swirling flows' local parameters has been increased. Development and advancement of the up to date computing models and national productivity software are very important for this process. All experimental works are carried out with up to date research methods of the local thermoshydraulic parameters, which enable one to reveal physical mechanisms of processes: PIV and LIV visualization techniques, high-speed and infrared photography, high speed registration of parameters of high-speed processes, etc. There is a problem of improvement of researchers' professional skills in the field of fluid mechanics to set adequately mathematics and physics problems of aerohydrodynamics for whirling and swirling flows and numerical and pilot investigations. It has been pointed out that issues of improvement of the cooling system and thermal protection effectiveness of heat-power and heat-transfer equipment units are still actual. It can be solved successfully using whirling and swirling flows as simple low power consumption exposing on the flow method and heat transfer augmentation.
Khan, Kashif Ali; Butt, Asma Rashid; Raza, Nauman
2018-03-01
In this study, an endeavor is to observe the unsteady two-dimensional boundary layer flow with heat and mass transfer behavior of Casson fluid past a stretching sheet in presence of wall mass transfer by ignoring the effects of viscous dissipation. Chemical reaction of linear order is also invoked here. Similarity transformation have been applied to reduce the governing equations of momentum, energy and mass into non-linear ordinary differential equations; then Homotopy analysis method (HAM) is applied to solve these equations. Numerical work is done carefully with a well-known software MATHEMATICA for the examination of non-dimensional velocity, temperature, and concentration profiles, and then results are presented graphically. The skin friction (viscous drag), local Nusselt number (rate of heat transfer) and Sherwood number (rate of mass transfer) are discussed and presented in tabular form for several factors which are monitoring the flow model.
Evaluation of magnetization transfer ratio in ascites and pelvic cystic masses
Energy Technology Data Exchange (ETDEWEB)
Okada, Susumu [Nippon Medical School, Inba, Chiba (Japan). Chiba-Hokuso Hospital; Kato, Tomoyasu; Yamashita, Takashi [and others
1997-12-01
To investigate the feasibility of magnetization transfer contrast (MTC) in characterization of pelvic cystic masses and ascites, in vitro studies were performed. Cystic fluids were taken from operative specimens of ten ovarian cystic masses (five mucinous cystadenomas, one cystadenocarcinoma, two serous cystadenocarcinomas, two clear cell carcinomas) and three non-ovarian pelvic cysts (one paraovarian cyst, one pseudomyxoma peritonei, one pelvic abscess). Samples of ascitic flied were drawn by peritoneal puncture in twenty patients (thirteen with peritonitis carcinomatosa, five with liver dysfunction, two with renal dysfunction). Total protein content in ascitic fluids was measured. Magnetization transfer ratio (MTR) was calculated by the signal intensities under the gradient echo sequence with and without the application of off-resonance pulses. The relative signal intensities (RSI) relative to water in T{sub 1} and T{sub 2} weighted images were obtained using spin echo sequence. There was no correlation between histological type of pelvic mass and MTR and RSI. Good correlation (R{sup 2}=0.761) was obtained between MTR and protein content in ascitic fluids, whereas no correlation was noted between RSI and protein content in ascitic fluids. These results suggest that MTC is not useful in the characterization of pelvic masses but is applicable in the differentiation between exudative ascites and transudative ascites. (author)
DEFF Research Database (Denmark)
Grathwohl, Peter; Haberer, Cristina; Ye, Yu
Diffusive–dispersive mass transfer in the capillary fringe is important for many groundwater quality issues such as transfer of volatile compounds into (and out of) the groundwater, the supply of oxygen for aerobic degradation of hydrocarbons as well as for precipitation of minerals (e.g. iron...... hydroxides). 2D-laboratory scale experiments were used to investigate the transfer of oxygen into groundwater under non-reactive and reactive conditions, at steady state and with water table fluctuations. Results show that transfer of oxygen is limited by transverse dispersion in the capillary fringe...... and the dispersion coefficients are the same as below the water table. Water table fluctuations cause temporarily increased fluxes of oxygen into groundwater during draining conditions and entrapped air after water table rise. High-permeability inclusions in the capillary fringe enhance mass transfer of oxygen...
Mass transfer effects in hygroscopic measurements of aerosol particles
Directory of Open Access Journals (Sweden)
M. N. Chan
2005-01-01
Full Text Available The tandem differential mobility analyzer (TDMA has been widely utilized to measure the hygroscopicity of laboratory-generated and atmospheric submicrometer particles. An important concern in investigating the hygroscopicity of the particles is if the particles have attained equilibrium state in the measurements. We present a literature survey to investigate the mass transfer effects in hygroscopicity measurements. In most TDMA studies, a residence time in the order of seconds is used for humidification (or dehumidification. NaCl and (NH42SO4 particles are usually used to verify the equilibrium measurements during this residence time, which is presumed to be sufficient for other particles. There have been observations that not all types of submicrometer particles, including atmospheric particles, attain their equilibrium sizes within this time scale. We recommend that experimentation with different residence times be conducted and that the residence time should be explicitly stated in future TDMA measurements. Mass transfer effects may also exist in the measurements of other properties related to the water uptake of atmospheric particles such as relative humidity dependent light scattering coefficients and cloud condensation nuclei activity.
Mass transfer of steels for FBR in sodium loop
International Nuclear Information System (INIS)
Susukida, Hiroshi; Yonezawa, Toshio; Ueda, Mitsuo; Imazu, Takayuki; Kiyokawa, Teruyuki.
1976-06-01
In order to grasp quantitatively the corrosion and mass transfer of steels for FBR in sodium loop and to establish their allowable stress value and corrosion rate, a special sodium loop for material testing was designed and fabricated and the steels were given 3010 hours exposing test in the sodium loop. This paper gives the outline of the sodium loop and the results of the test. (1) Carburization and a slight increase in weight were observed in the specimens of type 304 stainless steel exposed in the sodium loop for 3010 hours, while decarburization was observed in the specimens of 2 1/4 Cr-1 Mo steel. It is considered that these phenomena were caused by the downstream factor of the sodium loop. (2) A remarkable decrease of Charpy absorbed energy was observed in the specimens of type 304 stainless steel exposed in the sodium loop. It is considered that this resulted from the weakening of the grain boundary due to heat history and mass transfer. (3) The specimens exposed in the sodium loop must be washed by ultrasonic waves in a water bath after washing in alcohol. (auth.)
DEFF Research Database (Denmark)
Gilbert, Dorthea; Jakobsen, Hans H.; Winding, Anne
2014-01-01
as sink and source for polycyclic aromatic hydrocarbons (PAHs). This resulted in stable concentration gradients in water (>24 h). Adding the model organism Tetrahymena pyriformis to the experimental system enhanced PAH mass transfer up to hundred-fold (benzo[a]pyrene). Increasing mass transfer enhancement...
Evaporation of Ventilated Water Droplet: Connection Between Heat and Mass Transfer
Czech Academy of Sciences Publication Activity Database
Smolík, Jiří; Ondráčková, Lucie; Schwarz, Jaroslav; Kulmala, M.
2001-01-01
Roč. 32, č. 6 (2001), s. 739-748 ISSN 0021-8502 Institutional research plan: CEZ:AV0Z4072921 Keywords : droplet evaporation * heat and mass transfer Subject RIV: CC - Organic Chemistry Impact factor: 1.605, year: 2001
International Nuclear Information System (INIS)
Singh, K.; Rawat, S. K.; Kumar, M.
2016-01-01
Heat and mass transfer behavior of unsteady flow of squeezing between two parallel plates in the sight of uniform magnetic field with slip velocity effect is investigated. The governing equations representing fluid flow have been transformed into nonlinear ordinary differential equations using similarity transformation. The equations thus obtained have been solved numerically using Runge-Kutta-Fehlberg method with shooting technique. Effects on the behavior of velocity, temperature, and concentration for various values of relevant parameters are illustrated graphically. The skin-friction coefficient and heat and mass transfer rate are also tabulated for various governing parameters. The results indicate that, for nano fluid flow, the rates of heat and mass transfer are inversely proportional to nanoparticle volume fraction and magnetic parameter. The rate of mass transfer increases with increasing values of Schmidt number and squeeze number.
Mass transfer behavior in lactic acid fermentation using immobilized lactobacillus delbrueckii
Energy Technology Data Exchange (ETDEWEB)
Wang, H.; Seki, M.; Furusaki, S. [The University of Tokyo, Tokyo (Japan). Faculty of Engineering
1995-08-20
We performed simulation studies on mass transfer behavior for immobilized cells in lactic acid fermentation using the mathematical model developed previously. The simulations pointed to an unusual result; that lactate ion diffuses into the bead center from outside during the batch fermentation and the startup period of the continuous fermentation, whereas free lactic acid and protons diffuse in the opposite direction. This phenomenon is caused by the addition of base to keep pH constant in the broth. Also, using an appropriate buffer to control pH in the broth can reduce the inward diffusion of lactate ion and improve the productivity of lactic acid. A singular mass transfer phenomenon is expected to take place in other production processes using immobilized cells (or enzyme), where alkali solution is added to broth to keep pH constant. 9 refs., 6 figs.
International Nuclear Information System (INIS)
Zokaei-Kadijani, S.; Safdari, J.; Mousavian, M.A.; Rashidi, A.
2013-01-01
Highlights: ► Mass transfer coefficient does not depend on biomass concentration. ► The pulp density has a negative effect on mass transfer coefficient. ► The pulp density is the unique factor that affects maximum OUR. ► In this work, Neale’s correlation is corrected for prediction of mass transfer coefficient. ► Biochemical reaction is a limiting factor in the uranium bioleaching process. - Abstract: In this work, the volumetric oxygen mass transfer coefficient and the oxygen uptake rate (OUR) were studied for uranium ore bioleaching process by Acidthiobacillus ferrooxidans in a stirred tank reactor. The Box-Bohnken design method was used to study the effect of operating parameters on the oxygen mass transfer coefficient. The investigated factors were agitation speed (rpm), aeration rate (vvm) and pulp density (% weight/volume) of the stirred tank reactor. Analysis of experimental results showed that the oxygen mass transfer coefficient had low dependence on biomass concentration but had higher dependence on the agitation speed, aeration rate and pulp density. The obtained biological enhancement factors were equal to ones in experiments. On the other hand, the obtained values for Damkohler number (Da < 0.468) indicated that the process was limited by the biochemical reaction rate. Experimental results obtained for oxygen mass transfer coefficient were correlated with the empirical relations proposed by Garcia-Ochoa and Gomez (2009) and Neale and Pinches (1994). Due to the high relative error in the correlation of Neale and Pinches, that correlation was corrected and the coefficient of determination was calculated to be 89%. The modified correlation has been obtained based on a wide range of operating conditions, which can be used to determine the mass transfer coefficient in a bioreactor
International Nuclear Information System (INIS)
Sonetaka, Noriyoshi; Fan, Huan-Jung; Kobayashi, Seiji; Su, Yang-Chih; Furuya, Eiji
2009-01-01
In general, the adsorption uptake curve (AUC) can be easily determined in either intraparticle diffusion or liquid film mass transfer dominating systems. However, for both intraparticle diffusion and liquid film mass transfer controlling systems, the characterization of AUC is much more complicated, for example, when relatively small adsorbent particles are employed. In addition, there is no analytical solution available for both intraparticle diffusion and liquid film mass transfer controlling systems. Therefore, this paper is trying to characterize AUC for both intraparticle diffusion and liquid film mass transfer controlling adsorption systems using the shallow bed reactor technique. Typical parameters influencing AUC include liquid film mass transfer coefficient (k F ), effective intraparticle diffusivity (D S ), influent concentration (c 0 ) and equilibrium parameters (such as Freundlich isotherm constants k and 1/n). These parameters were investigated in this research and the simulated results indicated that the ratio of k F /D S and Freundlich constant 1/n had impact on AUC. Biot number (Bi) was used to replace the ratio of k F /D S in this study. Bi represents the ratio of the rate of transport across the liquid layer to the rate of intraparticle diffusion. Furthermore, Bi is much more significant than that of 1/n for AUC. Therefore, AUC can be characterized by Bi. In addition, the obtained Bi could be used to determine D S and k F simultaneously. Both parameters (D S and k F ) are important for designing and operating fixed bed reactors.
Connecting Dirac and Majorana neutrino mass matrices in the minimal left-right symmetric model.
Nemevšek, Miha; Senjanović, Goran; Tello, Vladimir
2013-04-12
Probing the origin of neutrino mass by disentangling the seesaw mechanism is one of the central issues of particle physics. We address it in the minimal left-right symmetric model and show how the knowledge of light and heavy neutrino masses and mixings suffices to determine their Dirac Yukawa couplings. This in turn allows one to make predictions for a number of high and low energy phenomena, such as decays of heavy neutrinos, neutrinoless double beta decay, electric dipole moments of charged leptons, and neutrino transition moments. We also discuss a way of reconstructing the neutrino Dirac Yukawa couplings at colliders such as the LHC.
Heat and mass transfers in the jets; Transferts de chaleur et de masse dans les jets
Energy Technology Data Exchange (ETDEWEB)
NONE
2001-07-01
This day on the heat and mass transfers in the jets, was organized by the SFT (French Society of Thermic) to present the state of the art in the domain. Fifteen presentations allowed the participants to discuss about turbulent flows, simulation of fluid flow and jets impacts. (A.L.B.)
Ariane, Mostapha; Kassinos, Stavros; Velaga, Sitaram; Alexiadis, Alessio
2018-04-01
In this paper, the mass transfer coefficient (permeability) of boundary layers containing motile cilia is investigated by means of discrete multi-physics. The idea is to understand the main mechanisms of mass transport occurring in a ciliated-layer; one specific application being inhaled drugs in the respiratory epithelium. The effect of drug diffusivity, cilia beat frequency and cilia flexibility is studied. Our results show the existence of three mass transfer regimes. A low frequency regime, which we called shielding regime, where the presence of the cilia hinders mass transport; an intermediate frequency regime, which we have called diffusive regime, where diffusion is the controlling mechanism; and a high frequency regime, which we have called convective regime, where the degree of bending of the cilia seems to be the most important factor controlling mass transfer in the ciliated-layer. Since the flexibility of the cilia and the frequency of the beat changes with age and health conditions, the knowledge of these three regimes allows prediction of how mass transfer varies with these factors. Copyright © 2018 Elsevier Ltd. All rights reserved.
3D modelling of coupled mass and heat transfer of a convection-oven roasting process
DEFF Research Database (Denmark)
Feyissa, Aberham Hailu; Adler-Nissen, Jens; Gernaey, Krist
2013-01-01
A 3D mathematical model of coupled heat and mass transfer describing oven roasting of meat has been developed from first principles. The proposed mechanism for the mass transfer of water is modified and based on a critical literature review of the effect of heat on meat. The model equations...... are based on a conservation of mass and energy, coupled through Darcy's equations of porous media - the water flow is mainly pressure-driven. The developed model together with theoretical and experimental assessments were used to explain the heat and water transport and the effect of the change...
Mass Transfer Coefficientin Stirred Tank for p -Cresol Extraction Process from Coal Tar
International Nuclear Information System (INIS)
Fardhyanti, D S; Tyaningsih, D S; Afifah, S N
2017-01-01
Indonesia is a country that has a lot of coal resources. The Indonesian coal has a low caloric value. Pyrolysis is one of the process to increase the caloric value. One of the by-product of the pyrolysis process is coal tar. It contains a lot of aliphatic or aromatic compounds such as p -cresol (11% v/v). It is widely used as a disinfectant. Extractionof p -Cresol increases the economic value of waste of coal. The aim of this research isto study about mass tranfer coefficient in the baffled stirred tank for p -Cresolextraction from coal tar. Mass transfer coefficient is useful for design and scale up of industrial equipment. Extraction is conducted in the baffled stirred tank equipped with a four-bladed axial impeller placed vertically in the vessel. Sample for each time processing (5, 10, 15, 20, 25 and 30minutes) was poured into a separating funnel, settled for an hour and separated into two phases. Then the two phases were weighed. The extract phases and raffinate phases were analyzed by Spectronic UV-Vis. The result showed that mixing speed of p -Cresol extraction increasesthe yield of p -Cresol and the mass transfer coefficient. The highest yield of p -Cresol is 49.32% and the highest mass transfer coefficient is 4.757 x 10 -6 kg/m 2 s. (paper)
Mass Transfer Coefficientin Stirred Tank for p-Cresol Extraction Process from Coal Tar
Fardhyanti, D. S.; Tyaningsih, D. S.; Afifah, S. N.
2017-04-01
Indonesia is a country that has a lot of coal resources. The Indonesian coal has a low caloric value. Pyrolysis is one of the process to increase the caloric value. One of the by-product of the pyrolysis process is coal tar. It contains a lot of aliphatic or aromatic compounds such asp-cresol (11% v/v). It is widely used as a disinfectant. Extractionof p-Cresol increases the economic value of waste of coal. The aim of this research isto study about mass tranfer coefficient in the baffled stirred tank for p-Cresolextraction from coal tar. Mass transfer coefficient is useful for design and scale up of industrial equipment. Extraction is conducted inthe baffled stirred tank equipped with a four-bladed axial impeller placed vertically in the vessel. Sample for each time processing (5, 10, 15, 20, 25 and 30minutes) was poured into a separating funnel, settled for an hour and separated into two phases. Then the two phases were weighed. The extract phases and raffinate phases were analyzed by Spectronic UV-Vis. The result showed that mixing speed of p-Cresol extraction increasesthe yield of p-Cresol and the mass transfer coefficient. The highest yield of p-Cresol is 49.32% and the highest mass transfer coefficient is 4.757 x 10-6kg/m2s.
Investigating mass transfer in symbiotic systems with hydrodynamic simulations
de Val-Borro, Miguel; Karovska, Margarita; Sasselov, Dimitar D.
2014-06-01
We investigate gravitationally focused wind accretion in binary systems consisting of an evolved star with a gaseous envelope and a compact accreting companion. We study the mass accretion and formation of an accretion disk around the secondary caused by the strong wind from the primary late-type component using global 2D and 3D hydrodynamic numerical simulations. In particular, the dependence on the mass accretion rate on the mass loss rate, wind temperature and orbital parameters of the system is considered. For a typical slow and massive wind from an evolved star the mass transfer through a focused wind results in rapid infall onto the secondary. A stream flow is created between the stars with accretion rates of a 2-10% percent of the mass loss from the primary. This mechanism could be an important method for explaining periodic modulations in the accretion rates for a broad range of interacting binary systems and fueling of a large population of X-ray binary systems. We test the plausibility of these accretion flows indicated by the simulations by comparing with observations of the symbiotic CH Cyg variable system.
Study of mass transfer at the air-water interface by an isotopic method
International Nuclear Information System (INIS)
Merlivat, L.
1975-01-01
It is shown by analysing the hydrogen and oxygen stable isotopes distribution in liquid and water vapor, that the processes taking place on a very small scale near the liquid can be investigated. The effect of molecular mass transfer is directly obtained without having to perform difficult measurements in the air in the immediate vicinity of the water surface. Experiments are carried out in the air-water tunnel especially designed for the simulation of ocean atmosphere energy exchanges. The wind velocities vary from 0.7 to 7m/sec. The experimental results obtained do not support the classical Reynolds' analogy between momentum and mass transfer down to the interface and the theory proposed by Sheppard, but they are in agreement with Sverdrup's, Kitaigorodskiy and Volkov's and Brutsaert's theories, all of which involve a layer just above the air-water interface through which mass transfer is dominated by molecular diffusion. The thickness of this layer in the two first theories is shown to decrease with increasing wind velocity. Direct application of Brutsaert's theory for roughness Reynolds numbers smaller than one is in good agreement with the experimental data obtained [fr
The effect of design and scale on the mixing and mass transfer in U-loop bioreactors
DEFF Research Database (Denmark)
Petersen, Leander Adrian Haaning; Villadsen, John; Jørgensen, Sten Bay
is altered? In this study we have investigated the mixing time and mass transfer capabilities of U-loop reactors of different geometries (high vs. diameter ratio) in pilot (0.15m3) and semi-industrial scales (2.2m3). A new expression for the mechanical power input into the system is also proposed, which......A system capable of handling a large volumetric gas fraction while providing a high gas to liquid mass transfer is a necessity if the metanotrophic bacterium Methylococcus capsulatus is to be used in single cell protein (SCP) production. Previous studies have proven that a U-loop fermenter, a novel...... indicates that an even more favorable relationship between power input and mass transfer rate (compared to previous literature) applies to U-loop fermenters....
The influence of surface treatment on mass transfer between air and building material
DEFF Research Database (Denmark)
Kwiatkowski, Jerzy; Rode, Carsten; Hansen, Kurt Kielsgaard
2008-01-01
for the experiments: gypsum board and calcium silicate. The wallpaper and paint were used as finishing materials. Impact of the following parameters for changes of RH was studied: coating, temperature and air movement. The measurements showed that acryl paint (diffusion open) can significantly decrease mass uptake......The processes of mass transfer between air and building structure and in the material influence not only the conditions within the material but also inside the connected air spaces. The material which absorbs and desorbs water vapour can be used to moderate the amplitude of indoor relative humidity...... and therefore to participate in the improvement of the indoor air quality and energy saving. Many parameters influence water vapour exchange between indoor air and building material. The aim of this work is to present the change of mass transfer under different climatic and material conditions. The measurements...
Mass Transfer and Kinetics Study of Heterogeneous Semi-Batch Precipitation of Magnesium Carbonate
DEFF Research Database (Denmark)
Han, B.; Qu, H. Y.; Niemi, H.
2014-01-01
Precipitation kinetics and mass transfer of magnesium carbonate (MgCO3) hydrates from a reaction of magnesium hydroxide (Mg(OH)(2)) and CO2 were analyzed. The effect of CO2 flow rate and mixing intensity on precipitation was investigated under ambient temperature and atmospheric pressure. Raman...... on the dissolution of Mg(OH)(2). In the researched system, the main driver of the precipitation kinetics was the mass transfer of CO2. Nesquehonite (MgCO3 center dot 3H(2)O), as needle-like crystals, was precipitated as the main product. Raman spectroscopy can serve as a potential tool to monitor the carbonation...
A general real-time formulation for multi-rate mass transfer problems
Directory of Open Access Journals (Sweden)
O. Silva
2009-08-01
Full Text Available 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.
Mass Transfer From Fundamentals to Modern Industrial Applications
Asano, Koichi
2006-01-01
This didactic approach to the principles and modeling of mass transfer as it is needed in modern industrial processes is unique in combining a step-by-step introduction to all important fundamentals with the most recent applications. Based upon the renowned author's successful new modeling method as used for the O-18 process, the exemplary exercises included in the text are fact-proven, taken directly from existing chemical plants. Fascinating reading for chemists, graduate students, chemical and process engineers, as well as thermodynamics physicists.
Heat and Mass Transfer Measurements for Tray-Fermented Fungal Products
Jou, R.-Y.; Lo, C.-T.
2011-01-01
In this study, heat and mass transfer in static tray fermentation, which is widely used in solid-state fermentation (SSF) to produce fungal products, such as enzymes or koji, is investigated. Specifically, kinetic models of transport phenomena in the whole-tray chamber are emphasized. The effects of temperature, moisture, and humidity on microbial growth in large-scale static tray fermentation are essential to scale-up SSF and achieve uniform fermentation. In addition, heat and mass transfer of static tray fermentation of Trichoderma fungi with two tray setups—traditional linen coverings and stacks in a temperature-humidity chamber is examined. In both these setups, the following factors of fermentation were measured: air velocity, air temperature, illumination, pH, carbon dioxide (CO2) concentration, and substrate temperature, and the effects of bed height, moisture of substrate, and relative humidity of air are studied. A thin (1 cm) bed at 28 °C and 95 % relative humidity is found to be optimum. Furthermore, mixing was essential for achieving uniform fermentation of Trichoderma fungi. This study has important applications in large-scale static tray fermentation of fungi.
FEHMN 1.0: Finite element heat and mass transfer code
International Nuclear Information System (INIS)
Zyvoloski, G.; Dash, Z.; Kelkar, S.
1991-04-01
A computer code is described which can simulate non-isothermal multiphase multicomponent flow in porous media. It is applicable to natural-state studies of geothermal systems and ground-water flow. The equations of heat and mass transfer for multiphase flow in porous and permeable media are solved using the finite element method. The permeability and porosity of the medium are allowed to depend on pressure and temperature. The code also has provisions for movable air and water phases and noncoupled tracers; that is, tracer solutions that do not affect the heat and mass transfer solutions. The tracers can be passive or reactive. The code can simulate two-dimensional, two-dimensional radial, or three-dimensional geometries. A summary of the equations in the model and the numerical solution procedure are provided in this report. A user's guide and sample problems are also included. The main use of FEHMN will be to assist in the understanding of flow fields in the saturated zone below the proposed Yucca Mountain Repository. 33 refs., 27 figs., 12 tabs
Determination of the gas-to-membrane mass transfer coefficient in a catalytic membrane reactor
Veldsink, J.W.; Versteeg, G.F.; Swaaij, W.P.M. van
1995-01-01
A novel method to determine the external mass transfer coefficient in catalytic membrane reactors (Sloot et al., 1992a, b) was presented in this study. In a catalytically active membrane reactor, in which a very fast reaction occurs, the external transfer coefficient can conveniently be measured by
Directory of Open Access Journals (Sweden)
Cláudio Vinicius Barbosa Monteiro
2010-07-01
Full Text Available The warming of a bottle of beer during a Friday evening happy hour directly involves transport phenomena, such as mass transfer due to condensation of air humidity on the bottle surface and heat transfer from the ambient to the bottle, which occurs by free convection and water condensation. Both processes happen simultaneously and are directly associated with the heat and mass transfer coefficients involved, which are affected by the ambient humidity and temperature. Several runs were made in several ambient conditions by exposing a cold bottle of beer to varied temperature and humidity and measuring the temperature of beer and the mass of water condensed on the bottle surface over time. From these measures, a theoretical and experimental methodology was developed and applied for the evaluation of the heat and mass transfer coefficients that govern this process. Both the relative humidity and ambient temperature exert a significant influence on the convective heat transfer coefficient. However, the mass transfer coefficient is affected only by the temperature.O aquecimento de uma garrafa de cerveja num “happy-hour” de sexta a tarde envolve diretamente os fenômenos de transferência de massa, devido à condensação da umidade do ar na superfície da garrafa, e de transferência de calor do meio para a garrafa, que ocorre por convecção natural e por condensação de vapor de água. Ambos os processos ocorrem simultaneamente e estão diretamente associados aos coeficientes de transferência de calor e massa envolvidos na dinâmica destes fenômenos e sofrem influência direta da umidade e temperatura ambientes. Neste contexto, efetuaram-se ensaios em diversas condições de temperatura e umidade ambientes, expondo-se uma garrafa de cerveja gelada ao ambiente e medindo-se a temperatura da cerveja e a massa de água condensada ao longo do tempo. A partir destas medidas, desenvolveu-se uma metodologia teórico-experimental que proporcionou a
Samsudin, Hayati; Auras, Rafael; Burgess, Gary; Dolan, Kirk; Soto-Valdez, Herlinda
2018-03-01
A two-step solution based on the boundary conditions of Crank's equations for mass transfer in a film was developed. Three driving factors, the diffusion (D), partition (K p,f ) and convective mass transfer coefficients (h), govern the sorption and/or desorption kinetics of migrants from polymer films. These three parameters were simultaneously estimated. They provide in-depth insight into the physics of a migration process. The first step was used to find the combination of D, K p,f and h that minimized the sums of squared errors (SSE) between the predicted and actual results. In step 2, an ordinary least square (OLS) estimation was performed by using the proposed analytical solution containing D, K p,f and h. Three selected migration studies of PLA/antioxidant-based films were used to demonstrate the use of this two-step solution. Additional parameter estimation approaches such as sequential and bootstrap were also performed to acquire a better knowledge about the kinetics of migration. The proposed model successfully provided the initial guesses for D, K p,f and h. The h value was determined without performing a specific experiment for it. By determining h together with D, under or overestimation issues pertaining to a migration process can be avoided since these two parameters are correlated. Copyright © 2017 Elsevier Ltd. All rights reserved.
Mixing and Mass Transfer in Industrial Bioreactors
DEFF Research Database (Denmark)
Villadsen, John
2015-01-01
Design of a real reactor for a real process in industrial scale requires much more than the design of the "ideal" reactors. This insight is formulated in empirical relations between key process parameters, such as mass and heat transfer coefficients, and the power input to the process. Mixing...... formulas are not in any way quantitatively correct, but based on dimensional analysis one is able to extrapolate from small-to large-scale operation. It is shown that linear scale-up may not give the smallest power input for a given mixing objective. The introduction presented is the basis...... for the visionary scale-up/scale-down design principles....
Katz, Brian G.; Plummer, L. Niel; Busenberg, Eurybiades; Revesz, Kinga M.; Jones, Blair F.; Lee, Terrie M.
1995-06-01
Chemical patterns along evolutionary groundwater flow paths in silicate and carbonate aquifers were interpreted using solute tracers, carbon and sulfur isotopes, and mass balance reaction modeling for a complex hydrologic system involving groundwater inflow to and outflow from a sinkhole lake in northern Florida. Rates of dominant reactions along defined flow paths were estimated from modeled mass transfer and ages obtained from CFC-modeled recharge dates. Groundwater upgradient from Lake Barco remains oxic as it moves downward, reacting with silicate minerals in a system open to carbon dioxide (CO2), producing only small increases in dissolved species. Beneath and downgradient of Lake Barco the oxic groundwater mixes with lake water leakage in a highly reducing, silicate-carbonate mineral environment. A mixing model, developed for anoxic groundwater downgradient from the lake, accounted for the observed chemical and isotopic composition by combining different proportions of lake water leakage and infiltrating meteoric water. The evolution of major ion chemistry and the 13C isotopic composition of dissolved carbon species in groundwater downgradient from the lake can be explained by the aerobic oxidation of organic matter in the lake, anaerobic microbial oxidation of organic carbon, and incongruent dissolution of smectite minerals to kaolinite. The dominant process for the generation of methane was by the CO2 reduction pathway based on the isotopic composition of hydrogen (δ2H(CH4) = -186 to -234‰) and carbon (δ13C(CH4) = -65.7 to -72.3‰). Rates of microbial metabolism of organic matter, estimated from the mass transfer reaction models, ranged from 0.0047 to 0.039 mmol L-1 yr-1 for groundwater downgradient from the lake.
International Nuclear Information System (INIS)
Xu, Peng; Gordon, Mark S.
2013-01-01
The charge transfer (CT) interaction, the most time-consuming term in the general effective fragment potential method, is made much more computationally efficient. This is accomplished by the projection of the quasiatomic minimal-basis-set orbitals (QUAMBOs) as the atomic basis onto the self-consistent field virtual molecular orbital (MO) space to select a subspace of the full virtual space called the valence virtual space. The diagonalization of the Fock matrix in terms of QUAMBOs recovers the canonical occupied orbitals and, more importantly, gives rise to the valence virtual orbitals (VVOs). The CT energies obtained using VVOs are generally as accurate as those obtained with the full virtual space canonical MOs because the QUAMBOs span the valence part of the virtual space, which can generally be regarded as “chemically important.” The number of QUAMBOs is the same as the number of minimal-basis MOs of a molecule. Therefore, the number of VVOs is significantly smaller than the number of canonical virtual MOs, especially for large atomic basis sets. This leads to a dramatic decrease in the computational cost
Saba, Julian; Dutta, Sucharita; Hemenway, Eric; Viner, Rosa
2012-01-01
Currently, glycans are attracting attention from the scientific community as potential biomarkers or as posttranslational modifications (PTMs) of therapeutic proteins. However, structural characterization of glycoproteins and glycopeptides remains analytically challenging. Here, we report on the implementation of a novel acquisition strategy termed higher-energy collision dissociation-accurate mass-product-dependent electron transfer dissociation (HCD-PD-ETD) on a hybrid linear ion trap-orbitrap mass spectrometer. This acquisition strategy uses the complementary fragmentations of ETD and HCD for glycopeptides analysis in an intelligent fashion. Furthermore, the approach minimizes user input for optimizing instrumental parameters and enables straightforward detection of glycopeptides. ETD spectra are only acquired when glycan oxonium ions from MS/MS HCD are detected. The advantage of this approach is that it streamlines data analysis and improves dynamic range and duty cycle. Here, we present the benefits of HCD-PD-ETD relative to the traditional alternating HCD/ETD for a trainer set containing twelve-protein mixture with two glycoproteins: human serotransferrin, ovalbumin and contaminations of two other: bovine alpha 1 acid glycoprotein (bAGP) and bovine fetuin.
Numerical study of heat and mass transfer during evaporation of a thin liquid film
Directory of Open Access Journals (Sweden)
Oubella M’hand
2015-01-01
Full Text Available A numerical study of mixed convection heat and mass transfer with film evaporation in a vertical channel is developed. The emphasis is focused on the effects of vaporization of three different liquid films having widely different properties, along the isothermal and wetted walls on the heat and mass transfer rates in the channel. The induced laminar downward flow is a mixture of blowing dry air and vapour of water, methanol or acetone, assumed as ideal gases. A two-dimensional steady state and elliptical flow model, connected with variable thermo-physical properties, is used and the phase change problem is based on thin liquid film assumptions. The governing equations of the model are solved by a finite volume method and the velocity-pressure fields are linked by SIMPLE algorithm. The numerical results, including the velocity, temperature and concentration profiles, as well as axial variations of Nusselt numbers, Sherwood number and dimensionless film evaporation rate are presented for two values of inlet temperature and Reynolds number. It was found that lower the inlet temperature and Re, the higher the induced flows cooling with respect of most volatile film. The better mass transfer rates related with film evaporation are found for a system with low mass diffusion coefficient.
Computational and experimental study of the effect of mass transfer on liquid jet break-up
Schetz, J. A.; Situ, M.
1983-06-01
A computational method has been developed to predict the effect of mass transfer on liquid jet break-up in coaxial, low velocity gas streams. Two conditions, both with and without the effect of mass transfer on the jet break-up, are calculated, and compared with experimental results and the classical linear theory. Methanol and water were used as the injectants. The numerical solution can predict the instantaneous shape of the jet surface and the break-up time, and it is very close to the experimental results. The numerical solutions and the experimental results both indicate that the wave number of the maximum instability is about 6.9, higher than 4.51 which was predicted by Rayleigh's linear theory. The experimental results and numerical solution show that the growth of the amplitude of the trough is faster than the growth of the amplitude of the crest, especially for a rapidly vaporizing jet. The numerical solutions show that for the small rates of evaporation, the effect of the mass transfer on the interface has a stabilizing effect near the wave number for maximum instability. Inversely, it has a destabilizing effect far from the wave number for maximum instability. For rapid evaporation, the effect of the mass transfer always has a destabilizing effect and decreases the break-up time of the jet.
Heat and mass transfer in air-fed pressurised suits
International Nuclear Information System (INIS)
Tesch, K.; Collins, M.W.; Karayiannis, T.G.; Atherton, M.A.; Edwards, P.
2009-01-01
Air-fed pressurised suits are used to protect workers against contamination and hazardous environments. The specific application here is the necessity for regular clean-up maintenance within the torus chamber of fusion reactors. The current design of suiting has been developed empirically. It is, therefore, very desirable to formulate a thermo-fluids model, which will be able to define optimum designs and operating parameters. Two factors indicate that the modelling should be as comprehensive as possible. Firstly, the overall thermo-fluids problem is three-dimensional and includes mass as well as heat transfer. The fluid field is complex, bounded on one side by the human body and on the other by what may be distensible, porous and multi-layer clothing. In this paper, we report firstly the modelling necessary for the additional mass and heat transport processes. This involves the use of Fick's and Fourier's laws and conjugate heat transfer. The results of an initial validation study are presented. Temperatures at the outlet of the suits were obtained experimentally and compared with those predicted by the overall CFD model. Realistic three-dimensional geometries were used for the suit and human body. Calculations were for turbulent flow with single- and two-component (species) models
Pangarkar, Chinmay; Dinh, Anh-Tuan; Mitragotri, Samir
2012-08-20
Lysosomes play a critical role in intracellular drug delivery. For enzyme-based therapies, they represent a potential target site whereas for nucleic acid or many protein drugs, they represent the potential degradation site. Either way, understanding the mechanisms and processes involved in routing of materials to lysosomes after cellular entry is of high interest to the field of drug delivery. Most therapeutic cargoes other than small hydrophobic molecules enter the cells through endocytosis. Endocytosed cargoes are routed to lysosomes via microtubule-based transport and are ultimately shared by various lysosomes via tethering and clustering of endocytic vesicles followed by exchange of their contents. Using a combined experimental and numerical approach, here we studied the rates of mass transfer into and among the endocytic vesicles in a model cell line, 3T3 fibroblasts. In order to understand the relationship of mass transfer with microtubular transport and vesicle clustering, we varied both properties through various pharmacological agents. At the same time, microtubular transport and vesicle clustering were modeled through diffusion-advection equations and the Smoluchowski equations, respectively. Our analysis revealed that the rate of mass transfer is optimally related to microtubular transport and clustering properties of vesicles. Further, the rate of mass transfer is highest in the innate state of the cell. Any perturbation to either microtubular transport or vesicle aggregation led to reduced mass transfer to lysosome. These results suggest that in the absence of an external intervention the endocytic pathway appears to maximize molecular delivery to lysosomes. Strategies are discussed to reduce mass transfer to lysosomes so as to extend the residence time of molecules in endosomes or late endosomes, thus potentially increasing the likelihood of their escape before disposition in the lysosomes. Copyright © 2012 Elsevier B.V. All rights reserved.
International Nuclear Information System (INIS)
2009-01-01
This book contains the short papers from the International Symposium on Convective heat and Mass Transfer in sustainable Energy ( Conv-09), organized on behalf of the International Centre for Heat and Mass Transfer, it was held on April 26- 1st May, In Hammamet, Tunisia. The objective of this conference is to bring together researchers in a forum to exchange innovative ideas, methods and results, and visions of the future related to the general theme of convective heat and mass transfer
International Nuclear Information System (INIS)
2009-01-01
This book contains the short papers from the International Symposium on convective heat and Mass Transfer in sustainable Energy ( conv-09), organized on behalf of the International Centre for Heat and Mass Transfer, it was held on April 26- 1st May, In Hammamet, Tunisia. The objective of this conference is to bring together researchers in a forum to exchange innovative ideas, methods and results, and visions of the future related to the general theme of convective heat and mass transfer
Directory of Open Access Journals (Sweden)
Grubecki Ireneusz
2017-06-01
Full Text Available It is known that external diffusional resistances are significant in immobilized enzyme packed-bed reactors, especially at large scales. Thus, the external mass transfer effects were analyzed for hydrogen peroxide decomposition by immobilized Terminox Ultra catalase in a packed-bed bioreactor. For this purpose the apparent reaction rate constants, kP, were determined by conducting experimental works at different superficial velocities, U, and temperatures. To develop an external mass transfer model the correlation between the Colburn factor, JD, and the Reynolds number, Re, of the type JD = K Re(n-1 was assessed and related to the mass transfer coefficient, kmL. The values of K and n were calculated from the dependence (am kp-1 - kR-1 vs. Re-1 making use of the intrinsic reaction rate constants, kR, determined before. Based on statistical analysis it was found that the mass transfer correlation JD = 0.972 Re-0.368 predicts experimental data accurately. The proposed model would be useful for the design and optimization of industrial-scale reactors.
International Nuclear Information System (INIS)
Christensen, Kristi; Rutledge, Veronica; Garn, Troy
2011-01-01
In support of the Nuclear Energy Advanced Modeling Simulation Safeguards and Separations (NEAMS SafeSep) program, the Idaho National Laboratory (INL) worked in collaboration with Los Alamos National Laboratory (LANL) to further a modeling effort designed to predict mass transfer behavior for selected metal species between individual dispersed drops and a continuous phase in a two phase liquid-liquid extraction (LLE) system. The purpose of the model is to understand the fundamental processes of mass transfer that occur at the drop interface. This fundamental understanding can be extended to support modeling of larger LLE equipment such as mixer settlers, pulse columns, and centrifugal contactors. The work performed at the INL involved gathering the necessary experimental data to support the modeling effort. A custom experimental apparatus was designed and built for performing drop contact experiments to measure mass transfer coefficients as a function of contact time. A high speed digital camera was used in conjunction with the apparatus to measure size, shape, and velocity of the drops. In addition to drop data, the physical properties of the experimental fluids were measured to be used as input data for the model. Physical properties measurements included density, viscosity, surface tension and interfacial tension. Additionally, self diffusion coefficients for the selected metal species in each experimental solution were measured, and the distribution coefficient for the metal partitioning between phases was determined. At the completion of this work, the INL has determined the mass transfer coefficient and a velocity profile for drops rising by buoyancy through a continuous medium under a specific set of experimental conditions. Additionally, a complete set of experimentally determined fluid properties has been obtained. All data will be provided to LANL to support the modeling effort.
Experimental study of convective coefficient of mass transfer of avocado (Persia americana Mill.)
Energy Technology Data Exchange (ETDEWEB)
Alves, Suerda Bezerra; Luiz, Marcia Ramos; Amorim, Joselma Araujo de; Gusmao, Rennam Pereira de; Gurgel, Jose Mauricio [Universidade Federal da Paraiba (LES/UFPB), Joao Pessoa, PB (Brazil). Lab. de Energia Solar
2010-07-01
Most of all energy consumed worldwide comes from fossil fuels derived from petroleum. With the petroleum crisis in the 70 were sought new energy sources, among them renewable. One such source is biodiesel energy, organic matter originated from animal and/or vegetable. Among the various plant species is the avocado (Persia americana Mill.) showing great potential in the production of petroleum extracted from the pulp and the alcohol removed from the seed. The main obstacle for obtaining the petroleum is the high humidity found in the pulp, being necessary to the drying process, which involves the transfer of heat and mass. The aim of this study was to use the mathematical model represented by Newton's Law of Cooling to simulate the mass transfer on the surface of the avocado pulp during the drying process. The equation of the mathematical model was solved numerically and the method of least squares was identified convective coefficient of Mass Transfer. The dryer used in the experimental process was operated with air flow in the vertical, air flow average fixed 3m/s and temperatures of 50, 60 and 70 deg C. The scheme of the dryer used in the research is composed of the following equipment: centrifugal fan, which drives the air-drying; valve, which allows control of airflow; electrical resistance, used for heating air; the drying chamber, where enables measurement of temperature and relative humidity; support for smaller trays; trays smaller, where the samples of the pulp of the avocado are placed; exit of the air of drying for the environment. The result presented shows the ratio of moisture content as a function of temperature over time, where it is possible to also observe that how much bigger the temperature of drying, greater will be the convective coefficient of mass transfer of the avocado. (author)
Minimal-change nephropathy and malignant thymoma.
Varsano, S; Bruderman, I; Bernheim, J L; Rathaus, M; Griffel, B
1980-05-01
A 56-year-old man had fever, precordial pain, and a mediastinal mass. The mass disappeared two months later and the patient remained asymptomatic for 2 1/2 years. At that time a full-blown nephrotic syndrome developed, with minimal-change glomerulopathy. The chest x-ray film showed the reappearance of a giant mediastinal mass. On biopsy of the mass, malignant thymoma was diagnosed. Association between minimal-change disease and Hodgkin's disease is well known, while the association with malignant thymoma has not been previously reported. The relationship between malignant thymoma and minimal-change disease is discussed, and a possible pathogenic mechanism involving cell-mediated immunity is proposed.
Visualization and mass transfer with a bistable two-slot impinging jet
Czech Academy of Sciences Publication Activity Database
Trávníček, Zdeněk; Maršík, František
2003-01-01
Roč. 6, č. 4 (2003), s. 337-441 ISSN 1343-8875 R&D Projects: GA AV ČR IAA2076203 Institutional research plan: CEZ:AV0Z2076919 Keywords : visualization * mass transfer * impinging jet Subject RIV: BK - Fluid Dynamics Impact factor: 0.279, year: 2002
International Nuclear Information System (INIS)
Hong, Sung Kook; Rhee, Dong Ho; Cho, Hyung Hee
2005-01-01
Impingement/effusion cooling technique is used for combustor liner or turbine parts cooling in gas turbine engine. In the impingement/effusion cooling system, the crossflow generated in the cooling channel induces an adverse effect on the cooling performance, which consequently affects the durability of the cooling system. In the present study, to reduce the adverse effect of the crossflow and improve the cooling performance, circular pin fins are installed in impingement/effusion cooling system and the heat transfer characteristics are investigated. The pin fins are installed between two perforated plates and the crossflow passes between these two plates. A blowing ratio is changed from 0.5 to 1.5 for the fixed jet Reynolds number of 10,000 and five circular pin fin arrangements are considered in this study. The local heat/mass transfer coefficients on the effusion plate are measured using a naphthalene sublimation method. The results show that local distributions of heat/mass transfer coefficient are changed due to the installation of pin fins. Due to the generation of vortex and wake by the pin fin, locally low heat/mass transfer regions are reduced. Moreover, the pin fin prevents the wall jet from being swept away, resulting in the increase of heat/mass transfer. When the pin fin is installed in front of the impinging jet, the blockage effect on the crossflow enhances the heat/mass transfer. However, the pin fin installed just behind the impinging jet blocks up the wall jet, decreasing the heat/mass transfer. As the blowing ratio increases, the pin fins lead to the higher Sh value compared to the case without pin fins, inducing 16%∼22% enhancement of overall Sh value at high blowing ratio of M=1.5
Aerodynamics, heat and mass transfer in steam-aerosol turbulent flows in containment
Energy Technology Data Exchange (ETDEWEB)
Nigmatulin, B.I.; Pershukov, V.A.; Ris, V.V. [Research & Engineering Centre of Nuclear Plants Safety, Moscow (Russian Federation)] [and others
1995-09-01
In this report an analysis of aerodynamic and heat transfer processes at the blowdown of gas-dispersed mixture into the containment volume is presented. A few models for description of the volume averaged and local characteristics are analyzed. The mathematical model for description of the local characteristics of the turbulent gas-dispersed flows was developed. The calculation of aerodynamic, heat and mass transfer characteristics was based on the Navier-Stokes, energy and gas mass fractions conservation equations. For calculation of dynamics and deposition of the aerosols the original diffusion-inertia model is developed. The pulsating characteristics of the gaseous phase were calculated on the base (k-{xi}) model of turbulence with modification to account thermogravitational force action and influence of particle mass loading. The appropriate boundary conditions using the {open_quotes}near-wall function{close_quotes} approach was obtained. Testing of the mathematical models and boundary conditions has shown a good agreement between computation and data of comparison. The described mathematical models were applied to two- and three dimensional calculations of the turbulent flow in containment at the various stages of the accident.
Heat and mass transfer at adiabatic evaporation of binary zeotropic solutions
Makarov, M. S.; Makarova, S. N.
2016-01-01
Results of numerical simulation of heat and mass transfer in a laminar flow of three-component gas at adiabatic evaporation of binary solutions from a flat plate are presented. The studies were carried out for the perfect solution of ethanol/methanol and zeotrope solutions of water/acetone, benzene/acetone, and ethanol/acetone. The liquid-vapor equilibrium is described by the Raoult law for the ideal solution and Carlson-Colburn model for real solutions. The effect of gas temperature and liquid composition on the heat and diffusion flows, and temperature of vapor-gas mixture at the interface is analyzed. The formula for calculating the temperature of the evaporation surface for the binary liquid mixtures using the similarity of heat and mass transfer was proposed. Data of numerical simulations are in a good agreement with the results of calculations based on the proposed dependence for all examined liquid mixtures in the considered range of temperatures and pressures.
Mass Transfer Model for a Breached Waste Package
International Nuclear Information System (INIS)
Hsu, C.; McClure, J.
2004-01-01
The degradation of waste packages, which are used for the disposal of spent nuclear fuel in the repository, can result in configurations that may increase the probability of criticality. A mass transfer model is developed for a breached waste package to account for the entrainment of insoluble particles. In combination with radionuclide decay, soluble advection, and colloidal transport, a complete mass balance of nuclides in the waste package becomes available. The entrainment equations are derived from dimensionless parameters such as drag coefficient and Reynolds number and based on the assumption that insoluble particles are subjected to buoyant force, gravitational force, and drag force only. Particle size distributions are utilized to calculate entrainment concentration along with geochemistry model abstraction to calculate soluble concentration, and colloid model abstraction to calculate colloid concentration and radionuclide sorption. Results are compared with base case geochemistry model, which only considers soluble advection loss
Energy Technology Data Exchange (ETDEWEB)
Liu, Cong; Zhang, Yinping [Department of Building Science, Tsinghua University, Beijing (China); Weschler, Charles J., E-mail: weschlch@rwjms.rutgers.edu [Department of Building Science, Tsinghua University, Beijing (China); Environmental and Occupational Health Sciences Institute, Rutgers University, Piscataway, NJ (United States); International Center for Indoor Environment and Energy, Technical University of Denmark, Lyngby (Denmark)
2014-11-01
Semi-volatile organic compounds (SVOCs) partition between the gas phase and airborne particles. The size distribution of particle-associated SVOCs impacts their fate in outdoor and indoor environments, as well as human exposure to these compounds and subsequent health risks. Allen et al. (1996) previously proposed that the rate of mass transfer can impact polycyclic aromatic hydrocarbon (PAH) partitioning among different sized particles, especially for time scales relevant to urban aerosols. The present study quantitatively builds on this idea, presenting a model that incorporates dynamic SVOC/particle interaction and applying this model to typical outdoor and indoor scenarios. The model indicates that the impact of mass transfer limitations on the size distribution of a particle-associated SVOC can be evaluated by the ratio of the time to achieve gas–particle equilibrium relative to the residence time of particles. The higher this ratio, the greater the influence of mass transfer limitations on the size distribution of particle-associated SVOCs. The influence of such constraints is largest on the fraction of particle-associated SVOCs in the coarse mode (> 2 μm). Predictions from the model have been found to be in reasonable agreement with size distributions measured for PAHs at roadside and suburban locations in Japan. The model also quantitatively explains shifts in the size distributions of particle associated SVOCs compared to those for particle mass, and the manner in which these shifts vary with temperature and an SVOC's molecular weight. - Highlights: • Rate of mass transfer can impact SVOC partitioning among different sized particles. • Model was developed that incorporates dynamic SVOC/particle sorption. • Key parameters: mass-transfer coefficients, partition coefficient, residence time • Model explains observed SVOC size distribution shifts with temperature and MW. • Largest impact of mass transfer constraints: SVOC sorption to coarse
International Nuclear Information System (INIS)
Burenko, V.A.; Krikis, V.V.; Popov, K.I.; Sabinin, V.A.; Shiskin, Z.A.
1984-01-01
The results of the investigations of physical models of heat and mass exchange apparatus of different design cannot be fully utilized in the calculations of industrial apparatus with large unit power in consequence of the scale factor which depends on the hydrodynamic conditions in the apparatus. An investigation was made of a fermentor, using instruments designed for measuring parameters such as the gas content, specific volumetric surface of phase contact, the speed of the liquid phase and the gas phase. The fermentor was designed for the biosynthesis of lysine. Calculating the true mass transfer coefficients in liquid, their dependence on the reduced air speed was obtained. The change of the true mass transfer coefficient in the liquid while its speed is constant shows that the mass transfer ability of bubble air lift apparatus does not depend on the reduced speed of the liquid phase but is directly dependent on the degree of turbulence of the stream, which in its turn is a function of the reduced air speed. The obtained quantitative regularities make it possible with sufficient accuracy to carry out hydrodynamic and mass transfer calculations of industrial apparatus of analogous design whose operating parameters lie within the investigated limits
Mass transfer model for two-layer TBP oxidation reactions: Revision 1
International Nuclear Information System (INIS)
Laurinat, J.E.
1994-01-01
To prove that two-layer, TBP-nitric acid mixtures can be safely stored in the Canyon evaporators, it must be demonstrated that a runaway reaction between TBP and nitric acid will not occur. Previous bench-scale experiments showed that, at typical evaporator temperatures, this reaction is endothermic and therefore cannot run away, due to the loss of heat from evaporation of water in the organic layer. However, the reaction would be exothermic and could run away if the small amount of water in the organic layer evaporates before the nitric acid in this layer is consumed by the reaction. Provided that there is enough water in the aqueous layer, this would occur if the organic layer is sufficiently thick so that the rate of loss of water by evaporation exceeds the rate of replenishment due to mixing with the aqueous layer. Bubbles containing reaction products enhance the rate of transfer of water from the aqueous layer to the organic layer. These bubbles are generated by the oxidation of TBP and its reaction products in the organic layer and by the oxidation of butanol in the aqueous layer. Butanol is formed by the hydrolysis of TBP in the organic layer. For aqueous-layer bubbling to occur, butanol must transfer into the aqueous layer. Consequently, the rate of oxidation and bubble generation in the aqueous layer strongly depends on the rate of transfer of butanol from the organic to the aqueous layer. This report presents measurements of mass transfer rates for the mixing of water and butanol in two-layer, TBP-aqueous mixtures, where the top layer is primarily TBP and the bottom layer is comprised of water or aqueous salt solution. Mass transfer coefficients are derived for use in the modeling of two-layer TBP-nitric acid oxidation experiments
International Nuclear Information System (INIS)
Balkan, F.
2005-01-01
A more realistic application of the entropy minimization principle EoEP is presented. This principle dictates uniform local entropy generations along the heat exchanger in order to minimize the total entropy generation rate due only to heat transfer. For a certain heat duty and area of an existing exchanger, this is done by changing the temperatures of one fluid while the temperatures of the other fluid are held constant. Since the heat duty is fixed, the change in the temperatures of the fluid after the change, however, may sometimes cause a drastic change in its flow rate. This may cause considerable changes in the overall heat transfer coefficient (U) and, consequently, in the entropy generation rate. Depending on the choice of the fluid for changing, the new entropy generation rates may be higher or lower than those based on constant U as is the case in papers recently published. So, the classical application of the EoEP principle needs to be modified to achieve more realistic entropy generation rates. In this study, the principle of EoEP with variable U is applied to some cases of heat exchange, and a simple method is presented as a criterion for the proper choice of the fluid to be changed
Energy Technology Data Exchange (ETDEWEB)
Saadi, B
2006-04-15
Most metallurgical processes, such as steel refining or nuclear waste processing; the interfaces between two liquid phases are the regions of mass transfer. These transfers require the implementation of a means of stirring to accelerate the kinetics of the pollutants transfer between both phases. This thesis deals with the use of the electromagnetic forces to stir, without any material contact, the bath core and the interface in order to control or even increase the kinetic transfers. To achieve this, two complementary experimental installations were used. The first experiment allows the measurement of the Indium transfer, initially dissolved in mercury towards a covering electrolyte layer and the velocity field in mercury. The performed experiments, determine the topology of the fields flows speeds in the mercury bath, moreover the behaviour of the transfer kinetics versus the intensity of the magnetic field are established. This evolution is correlated with the dynamic behaviour of the mercury surface. The second installation allows the characterization of an element transfer (Pb, Zr or Ce) initially contained in a fluorinated salt towards an antimony matrix containing lithium. It appears that all transfers kinetics are very fast. The proposed experimental set-up is particularly efficient for Cerium transfer (limited by the interface) but does not present any action for Zirconium transfer. (author)
MASS TRANSFER CONTROL OF A BACKWARD-FACING STEP FLOW BY LOCAL FORCING- EFFECT OF REYNOLDS NUMBER
Directory of Open Access Journals (Sweden)
Zouhaier MEHREZ
2011-01-01
Full Text Available The control of fluid mechanics and mass transfer in separated and reattaching flow over a backward-facing step by a local forcing, is studied using Large Eddy Simulation (LES.To control the flow, the local forcing is realized by a sinusoidal oscillating jet at the step edge. The Reynolds number is varied in the range 10000 ≤ Re≤ 50000 and the Schmidt number is fixed at 1.The found results show that the flow structure is modified and the local mass transfer is enhanced by the applied forcing. The observed changes depend on the Reynolds number and vary with the frequency and amplitude of the local forcing. For the all Reynolds numbers, the largest recirculation zone size reduction is obtained at the optimum forcing frequency St = 0.25. At this frequency the local mass transfer enhancement attains the maximum.
International Nuclear Information System (INIS)
Park, Sang Kyoo; Yang, Hei Cheon
2017-01-01
As stricter environmental regulation have led to an increase in the water treatment cost, it is necessary to quantitatively study the input power of the aeration process to improve the energy efficiency of the water treatment processes. The objective of this study is to propose the empirical correlations for the mass transfer coefficient with the gas hold-up and input power in order to investigate the mass transfer characteristics of the aeration process. It was found that as the input power increases, the mass transfer coefficient increases because of the decrease of gas hold-up and increase of Reynolds number, the penetration length, and dispersion of mixed flow. The correlations for the volumetric mass transfer coefficients with gas hold-up and input power were consistent with the experimental data, with the maximum deviation less than approximately ±10.0%.
Energy Technology Data Exchange (ETDEWEB)
Park, Sang Kyoo; Yang, Hei Cheon [Chonnam Nat’l Univ., Gwangju (Korea, Republic of)
2017-06-15
As stricter environmental regulation have led to an increase in the water treatment cost, it is necessary to quantitatively study the input power of the aeration process to improve the energy efficiency of the water treatment processes. The objective of this study is to propose the empirical correlations for the mass transfer coefficient with the gas hold-up and input power in order to investigate the mass transfer characteristics of the aeration process. It was found that as the input power increases, the mass transfer coefficient increases because of the decrease of gas hold-up and increase of Reynolds number, the penetration length, and dispersion of mixed flow. The correlations for the volumetric mass transfer coefficients with gas hold-up and input power were consistent with the experimental data, with the maximum deviation less than approximately ±10.0%.
Minimal and non-minimal standard models: Universality of radiative corrections
International Nuclear Information System (INIS)
Passarino, G.
1991-01-01
The possibility of describing electroweak processes by means of models with a non-minimal Higgs sector is analyzed. The renormalization procedure which leads to a set of fitting equations for the bare parameters of the lagrangian is first reviewed for the minimal standard model. A solution of the fitting equations is obtained, which correctly includes large higher-order corrections. Predictions for physical observables, notably the W boson mass and the Z O partial widths, are discussed in detail. Finally the extension to non-minimal models is described under the assumption that new physics will appear only inside the vector boson self-energies and the concept of universality of radiative corrections is introduced, showing that to a large extent they are insensitive to the details of the enlarged Higgs sector. Consequences for the bounds on the top quark mass are also discussed. (orig.)
Hussain, Amir; Kangwa, Martin; Yumnam, Nivedita; Fernandez-Lahore, Marcelo
2015-01-01
The influence of internal mass transfer on productivity as well as the performance of packed bed bioreactor was determined by varying a number of parameters; chitosan coating, flow rate, glucose concentration and particle size. Saccharomyces cerevisiae cells were immobilized in chitosan and non-chitosan coated alginate beads to demonstrate the effect on particle side mass transfer on substrate consumption time, lag phase and ethanol production. The results indicate that chitosan coating, bead...
Piva, Stephano P. T.; Pistorius, P. Chris; Webler, Bryan A.
2018-05-01
During high-temperature confocal scanning laser microscopy (HT-CSLM) of liquid steel samples, thermal Marangoni flow and rapid mass transfer between the sample and its surroundings occur due to the relatively small sample size (diameter around 5 mm) and large temperature gradients. The resulting evaporation and steel-slag reactions tend to change the chemical composition in the metal. Such mass transfer effects can change observed nonmetallic inclusions. This work quantifies oxide-metal-gas mass transfer of solutes during HT-CSLM experiments using computational simulations and experimental data for (1) dissolution of MgO inclusions in the presence and absence of slag and (2) Ca, Mg-silicate inclusion changes upon exposure of a Si-Mn-killed steel to an oxidizing gas atmosphere.
International Nuclear Information System (INIS)
Kholpanov, L.P.; Babak, T.B.; Babak, V.N.; Malyusov, V.A.; Zhavoronkov, N.M.; AN SSSR, Moscow. Inst. Obshchej i Neorganicheskoj Khimii)
1980-01-01
To determine the ways of intensification of heat and mass transfer processes, the direct flow and counterflow heat and mass transfer is analytically investigated during the turbulent flow of a liquid and gas film on the basis of solving the energy equation for liquid and gas film, i.e. the two-phase film heat transfer is investigated from the position of a conjugate task. The analysis of the two-phase heat transfer has shown that it is necessary to know the position of each point in a plane before using this or that formula. Depending on its position on this plane, the heat transfer process will be determined by one or two phases only. It is found, that in the case of a single-phase heat transfer the temperature on the surface remains stable over the channel length. In the case of a two-phase heat transfer it can significantly change over the channel length [ru
International Nuclear Information System (INIS)
Sokolov, V.V.; Smirnov, N.N.
1982-01-01
An investigation of the joint influence of hydrodynamic and concentration factors in sorption of iodine by AV-17-8 and anion exchange resins on the mass-transfer coefficient is the subject of this report. The method of central composite rotatable experimental design was used for quantitative assessment and derivation of the appropriate equations. The investigation yielded the necessary regression equations satisfactorily describing the influence of all the factors in the mass-transfer coefficient. the optimal mass-transfer conditions were determined. On the basis of the values obtained, recommendations are made on the optimal hydrodynamic conditions of operation of equipment with pneumatic circulation of the ion-exchanger
Abd Elazem, Nader Y.; Ebaid, Abdelhalim
2017-12-01
In this paper, the effect of partial slip boundary condition on the heat and mass transfer of the Cu-water and Ag-water nanofluids over a stretching sheet in the presence of magnetic field and radiation. Such partial slip boundary condition has attracted much attention due to its wide applications in industry and chemical engineering. The flow is basically governing by a system of partial differential equations which are reduced to a system of ordinary differential equations. This system has been exactly solved, where exact analytical expression has been obtained for the fluid velocity in terms of exponential function, while the temperature distribution, and the nanoparticles concentration are expressed in terms of the generalized incomplete gamma function. In addition, explicit formulae are also derived from the rates of heat transfer and mass transfer. The effects of the permanent parameters on the skin friction, heat transfer coefficient, rate of mass transfer, velocity, the temperature profile, and concentration profile have been discussed through tables and graphs.
DEFF Research Database (Denmark)
Feyissa, Aberham Hailu; Gernaey, Krist; Adler-Nissen, Jens
2012-01-01
to uncertainty in the model predictions. The aim of the current paper is to address this uncertainty challenge in the modelling of food production processes using a combination of uncertainty and sensitivity analysis, where the uncertainty analysis and global sensitivity analysis were applied to a heat and mass......Similar to other processes, the modelling of heat and mass transfer during food processing involves uncertainty in the values of input parameters (heat and mass transfer coefficients, evaporation rate parameters, thermo-physical properties, initial and boundary conditions) which leads...
International Nuclear Information System (INIS)
Vorotyntsev, M.A.
1991-01-01
Key problems of turbulent mass transfer at a solid wall are reviewed: closure problem for the concentration field, information on wall turbulence, applications of microelectrodes to study the structure of turbulence, correlation properties of current fluctuations. (author). 26 refs
A deep learning approach for the analysis of masses in mammograms with minimal user intervention.
Dhungel, Neeraj; Carneiro, Gustavo; Bradley, Andrew P
2017-04-01
We present an integrated methodology for detecting, segmenting and classifying breast masses from mammograms with minimal user intervention. This is a long standing problem due to low signal-to-noise ratio in the visualisation of breast masses, combined with their large variability in terms of shape, size, appearance and location. We break the problem down into three stages: mass detection, mass segmentation, and mass classification. For the detection, we propose a cascade of deep learning methods to select hypotheses that are refined based on Bayesian optimisation. For the segmentation, we propose the use of deep structured output learning that is subsequently refined by a level set method. Finally, for the classification, we propose the use of a deep learning classifier, which is pre-trained with a regression to hand-crafted feature values and fine-tuned based on the annotations of the breast mass classification dataset. We test our proposed system on the publicly available INbreast dataset and compare the results with the current state-of-the-art methodologies. This evaluation shows that our system detects 90% of masses at 1 false positive per image, has a segmentation accuracy of around 0.85 (Dice index) on the correctly detected masses, and overall classifies masses as malignant or benign with sensitivity (Se) of 0.98 and specificity (Sp) of 0.7. Copyright © 2017 Elsevier B.V. All rights reserved.
Mass transfer coefficient of slug flow for organic solvent-aqueous system in a microreactor
Energy Technology Data Exchange (ETDEWEB)
Tuek, Ana Jurinjak; Anic, Iva; Kurtanjek, Zelimir; Zelic, Bruno [University of Zagreb, Zagreb (Croatia)
2015-06-15
Application of microreactor systems could be the next break-through in the intensification of chemical and biochemical processes. The common flow regime for organic solvent-aqueous phase two-phase systems is a segmented flow. Internal circulations in segments cause high mass transfer and conversion. We analyzed slug flow in seven systems of organic solvents and aqueous phase. To analyze how slug lengths in tested systems depend on linear velocity and physical and chemical properties of used organic solvents, regression models were proposed. It was shown that models based on linearization of approximation by potentials give low correlation for slug length prediction; however, application of an essential nonlinear model of multiple layer perception (MLP) neural network gives high correlation with R{sup 2}=0.9. General sensitivity analysis was applied for the MLP neural network model, which showed that 80% of variance in slug length for the both phases is accounted for the viscosity and density of the organic phases; 10% is accounted by surface tension of the organic phase, while molecular masses and flow rates each account for 5%. For defined geometry of microreactor, mass transfer has been determined by carrying out the neutralization experiment with NaOH where acetic acid diffuses from organic phase (hexane) into aqueous phase. Estimated mass transfer coefficients were in the range k{sub L}a=4,652-1,9807 h{sup -1}.
Mass transfer coefficient of slug flow for organic solvent-aqueous system in a microreactor
International Nuclear Information System (INIS)
Tuek, Ana Jurinjak; Anic, Iva; Kurtanjek, Zelimir; Zelic, Bruno
2015-01-01
Application of microreactor systems could be the next break-through in the intensification of chemical and biochemical processes. The common flow regime for organic solvent-aqueous phase two-phase systems is a segmented flow. Internal circulations in segments cause high mass transfer and conversion. We analyzed slug flow in seven systems of organic solvents and aqueous phase. To analyze how slug lengths in tested systems depend on linear velocity and physical and chemical properties of used organic solvents, regression models were proposed. It was shown that models based on linearization of approximation by potentials give low correlation for slug length prediction; however, application of an essential nonlinear model of multiple layer perception (MLP) neural network gives high correlation with R 2 =0.9. General sensitivity analysis was applied for the MLP neural network model, which showed that 80% of variance in slug length for the both phases is accounted for the viscosity and density of the organic phases; 10% is accounted by surface tension of the organic phase, while molecular masses and flow rates each account for 5%. For defined geometry of microreactor, mass transfer has been determined by carrying out the neutralization experiment with NaOH where acetic acid diffuses from organic phase (hexane) into aqueous phase. Estimated mass transfer coefficients were in the range k L a=4,652-1,9807 h -1
Ghanbarian, Davoud; Baraani Dastjerdi, Mojtaba; Torki-Harchegani, Mehdi
2016-05-01
An accurate understanding of moisture transfer parameters, including moisture diffusivity and moisture transfer coefficient, is essential for efficient mass transfer analysis and to design new dryers or improve existing drying equipments. The main objective of the present study was to carry out an experimental and theoretical investigation of mushroom slices drying and determine the mass transfer characteristics of the samples dried under different conditions. The mushroom slices with two thicknesses of 3 and 5 mm were dried at air temperatures of 40, 50 and 60 °C and air flow rates of 1 and 1.5 m s-1. The Dincer and Dost model was used to determine the moisture transfer parameters and predict the drying curves. It was observed that the entire drying process took place in the falling drying rate period. The obtained lag factor and Biot number indicated that the moisture transfer in the samples was controlled by both internal and external resistance. The effective moisture diffusivity and the moisture transfer coefficient increased with increasing air temperature, air flow rate and samples thickness and varied in the ranges of 6.5175 × 10-10 to 1.6726 × 10-9 m2 s-1 and 2.7715 × 10-7 to 3.5512 × 10-7 m s-1, respectively. The validation of the Dincer and Dost model indicated a good capability of the model to describe the drying curves of the mushroom slices.
Fluid and mass transfer at subduction interfaces-The field metamorphic record
Bebout, Gray E.; Penniston-Dorland, Sarah C.
2016-01-01
The interface between subducting oceanic slabs and the hanging wall is a structurally and lithologically complex region. Chemically disparate lithologies (sedimentary, mafic and ultramafic rocks) and mechanical mixtures thereof show heterogeneous deformation. These lithologies are tectonically juxtaposed at mm to km scales, particularly in more intensely sheared regions (mélange zones, which act as fluid channelways). This juxtaposition, commonly in the presence of a mobile fluid phase, offers up huge potential for mass transfer and related metasomatic alteration. Fluids in this setting appear capable of transporting mass over scales of kms, along flow paths with widely varying geometries and P-T trajectories. Current models of arc magmatism require km-scale migration of fluids from the interface into mantle wedge magma source regions and implicit in these models is the transport of any fluids generated in the subducting slab along and ultimately through the subduction interface. Field and geochemical studies of high- and ultrahigh-pressure metamorphic rocks elucidate the sources and compositions of fluids in subduction interfaces and the interplay between deformation and fluid and mass transfer in this region. Recent geophysical studies of the subduction interface - its thickness, mineralogy, density, and H2O content - indicate that its rheology greatly influences the ways in which the subducting plate is coupled with the hanging wall. Field investigation of the magnitude and styles of fluid-rock interaction in metamorphic rocks representing "seismogenic zone" depths (and greater) yields insight regarding the roles of fluids and elevated fluid pore pressure in the weakening of plate interface rocks and the deformation leading to seismic events. From a geochemical perspective, the plate interface contributes to shaping the "slab signature" observed in studies of the composition of arc volcanic rocks. Understanding the production of fluids with hybridized chemical
Directory of Open Access Journals (Sweden)
Cláudio Vinicius Barbosa Monteiro
2010-07-01
Full Text Available The warming of a bottle of beer during a Friday evening happy hour directly involves transport phenomena, such as mass transfer due to condensation of air humidity on the bottle surface and heat transfer from the ambient to the bottle, which occurs by free convection and water condensation. Both processes happen simultaneously and are directly associated with the heat and mass transfer coefficients involved, which are affected by the ambient humidity and temperature. Several runs were made in several ambient conditions by exposing a cold bottle of beer to varied temperature and humidity and measuring the temperature of beer and the mass of water condensed on the bottle surface over time. From these measures, a theoretical and experimental methodology was developed and applied for the evaluation of the heat and mass transfer coefficients that govern this process. Both the relative humidity and ambient temperature exert a significant influence on the convective heat transfer coefficient. However, the mass transfer coefficient is affected only by the temperature.
Esperança, M N; Cunha, F M; Cerri, M O; Zangirolami, T C; Farinas, C S; Badino, A C
2014-05-01
Sugarcane bagasse is a low-cost and abundant by-product generated by the bioethanol industry, and is a potential substrate for cellulolytic enzyme production. The aim of this work was to evaluate the effects of air flow rate (QAIR), solids loading (%S), sugarcane bagasse type, and particle size on the gas hold-up (εG) and volumetric oxygen transfer coefficient (kLa) in three different pneumatic bioreactors, using response surface methodology. Concentric tube airlift (CTA), split-cylinder airlift (SCA), and bubble column (BC) bioreactor types were tested. QAIR and %S affected oxygen mass transfer positively and negatively, respectively, while sugarcane bagasse type and particle size (within the range studied) did not influence kLa. Using large particles of untreated sugarcane bagasse, the loop-type bioreactors (CTA and SCA) exhibited higher mass transfer, compared to the BC reactor. At higher %S, SCA presented a higher kLa value (0.0448 s−1) than CTA, and the best operational conditions in terms of oxygen mass transfer were achieved for %S 27.0 L min−1. These results demonstrated that pneumatic bioreactors can provide elevated oxygen transfer in the presence of vegetal biomass, making them an excellent option for use in three-phase systems for cellulolytic enzyme production by filamentous fungi.
Effect of mass transfer in a recirculation batch reactor system for immobilized penicillin amidase.
Park, J M; Choi, C Y; Seong, B L; Han, M H
1982-10-01
The effect of external mass transfer resistance on the overall reaction rate of the immobilized whole cell penicillin amidase of E. coli in a recirculation batch reactor was investigated. The internal diffusional resistance was found negligible as indicated by the value of effectiveness factor, 0.95. The local environmental change in a column due to the pH drop was successfully overcome by employing buffer solution. The reaction rate was measured by pH-stat method and was found to follow the simple Michaelis-Menten law at the initial stage of the reaction. The values of the net reaction rate experimentally determined were used to calculate the substrate concentration at the external surface of the catalyst pellet and then to calculate the mass transfer coefficient, k(L), at various flow rates and substrate concentrations. The correlation proposed by Chilton and Colburn represented adequately the experimental data. The linear change of log j(D) at low log N(Re) with negative slope was ascribed to the fact that the external mass transfer approached the state of pure diffusion in the limit of zero superficial velocity.
Xu, Yu; Wang, Hong; Nussinov, Ruth; Ma, Buyong
2013-01-01
We constructed and simulated a ‘minimal proteome’ model using Langevin dynamics. It contains 206 essential protein types which were compiled from the literature. For comparison, we generated six proteomes with randomized concentrations. We found that the net charges and molecular weights of the proteins in the minimal genome are not random. The net charge of a protein decreases linearly with molecular weight, with small proteins being mostly positively charged and large proteins negatively charged. The protein copy numbers in the minimal genome have the tendency to maximize the number of protein-protein interactions in the network. Negatively charged proteins which tend to have larger sizes can provide large collision cross-section allowing them to interact with other proteins; on the other hand, the smaller positively charged proteins could have higher diffusion speed and are more likely to collide with other proteins. Proteomes with random charge/mass populations form less stable clusters than those with experimental protein copy numbers. Our study suggests that ‘proper’ populations of negatively and positively charged proteins are important for maintaining a protein-protein interaction network in a proteome. It is interesting to note that the minimal genome model based on the charge and mass of E. Coli may have a larger protein-protein interaction network than that based on the lower organism M. pneumoniae. PMID:23420643
2013-01-01
In this study, a miniature stirred tank bioreactor was designed for treatment of waste gas containing benzene, toluene and xylene. Oxygen mass transfer characteristics for various twin and single-impeller systems were investigated for 6 configurations in a vessel with 10 cm of inner diameter and working volume of 1.77L. Three types of impellers, namely, Rushton turbine, Pitched 4blades and Pitched 2blades impellers with downward pumping have been used. Deionized water was used as a liquid phase. With respect to other independent variables such as agitation speed, aeration rate, type of sparger, number of impellers, the relative performance of these impellers was assessed by comparing the values of (KLa) as a key parameter. Based on the experimental data, empirical correlations as a function of the operational conditions have been proposed, to study the oxygen transfer rates from air bubbles generated in the bioreactor. It was shown that twin Rushton turbine configuration demonstrates superior performance (23% to 77% enhancement in KLa) compared with other impeller compositions and that sparger type has negligible effect on oxygen mass transfer rate. Agitation speeds of 400 to 800 rpm were the most efficient speeds for oxygen mass transfer in the stirred bioreactor. PMID:23369581
Tang, Bing; Song, Haoliang; Bin, Liying; Huang, Shaosong; Zhang, Wenxiang; Fu, Fenglian; Zhao, Yiliang; Chen, Qianyu
2017-10-01
The work aims at illustrating the profile of DO and its mass transferring process in a biofilm reactor packed with a novel semi-suspended bio-carrier, and further revealing the main factors that influence the mass transferring coefficient of DO within the biofilm. Results showed that the biofilm was very easy to attach and grow on the semi-suspended bio-carrier, which obviously changed the DO profile inside and outside the biofilm. The semi-suspended bio-carrier caused three different mass transfer zones occurring in the bioreactor, including the zones of bulk solution, boundary layer and biofilm, in which, the boundary layer zone had an obvious higher mass transfer resistance. Increasing the aeration rate might improve the hydrodynamic conditions in the bioreactor and accelerate the mass transfer of DO, but it also detached the biofilm from the surface of bio-carrier, which reduced the consumption of DO, and accordingly, decreased the DO gradient in the bioreactor. Copyright © 2017 Elsevier Ltd. All rights reserved.
Determination of the mass-transfer coefficient in liquid phase in a stream-bubble contact device
Dmitriev, A. V.; Dmitrieva, O. S.; Madyshev, I. N.
2016-09-01
One of the most effective energy saving technologies is the improvement of existing heat and mass exchange units. A stream-bubble contact device is designed to enhance the operation efficiency of heat and mass exchange units. The stages of the stream-bubble units that are proposed by the authors for the decarbonization process comprise contact devices with equivalent sizes, whose number is determined by the required performance of a unit. This approach to the structural design eliminates the problems that arise upon the transition from laboratory samples to industrial facilities and makes it possible to design the units of any required performance without a decrease in the effectiveness of mass exchange. To choose the optimal design that provides the maximum effectiveness of the mass-exchange processes in units and their intensification, the change of the mass-transfer coefficient is analyzed with the assumption of a number of parameters. The results of the study of the effect of various structural parameters of a stream-bubble contact device on the mass-transfer coefficient in the liquid phase are given. It is proven that the mass-transfer coefficient increases in the liquid phase, in the first place, with the growth of the level of liquid in the contact element, because the rate of the liquid run-off grows in this case and, consequently, the time of surface renewal is reduced; in the second place, with an increase in the slot diameter in the downpipe, because the jet diameter and, accordingly, their section perimeter and the area of the surface that is immersed in liquid increase; and, in the third place, with an increase in the number of slots in the downpipe, because the area of the surface that is immersed in the liquid of the contact element increases. Thus, in order to increase the mass-transfer coefficient in the liquid phase, it is necessary to design the contact elements with a minimum width and a large number of slots and their increased diameter; in
International Nuclear Information System (INIS)
Liu, X.H.; Yi, X.Q.; Jiang, Y.
2011-01-01
Mass transfer performance of two commonly used liquid desiccants, LiBr aqueous solution and LiCl aqueous solution, is compared in this paper on the basis of the same solution temperature and surface vapor pressure. According to the analysis of the analytical solutions of heat and mass transfer processes, the key performance influencing factors are heat capacity ratio of air to desiccant m * and mass transfer unit NTU m . The heat capacities of the two liquid desiccants are about the same at same volumetric flow rate, and LiBr solution has higher density and smaller specific heat capacity. The variance of mass transfer unit with different operating conditions and liquid desiccants are derived based on the experimental results. In the condition of the same desiccant mass flow rate, the dehumidification performance of LiCl solution is better, and the regeneration performance of LiBr solution is a little better or almost the same as that of LiCl solution. In the condition of the same desiccant volumetric flow rate, the dehumidification performance of LiCl solution is a little better or about the same compared with LiBr solution, and the regeneration performance of LiBr solution is better. The COPs of the liquid desiccant systems using these two desiccants are similar; while LiCl solution costs 18% lower than LiBr solution at current Chinese price.
International Nuclear Information System (INIS)
Ogawa, Masuro
1992-10-01
In the present paper, mass transfer has been numerically studied in a laminar flow through a circular graphite tube to evaluate graphite corrosion rate and generation rate of carbon monoxide during a pipe rupture accident in a high temperature gas cooled reactor. In the analysis, heterogeneous (graphite oxidation and graphite/carbon dioxide reaction) and homogeneous (carbon monoxide combustion) chemical reactions were dealt in the multi-component gas mixture; helium, oxygen, carbon monoxide and carbon dioxide. Multi-component diffusion coefficients were used in a diffusion term. Mass conservation equations of each gas component, mass conservation equation and momentum conservation equations of the gas mixture were solved by using SIMPLE algorism. Chemical reactions between graphite and oxygen, graphite and carbon dioxide, and carbon monoxide combustion were taken into account in the present numerical analysis. An energy equation for the gas mixture was not solved and temperature was held to be constant in order to understand basic mass transfer characteristics without heat transfer. But, an energy conservation equation for single component gas was added to know heat transfer characteristics without mass transfer. The effects of these chemical reactions on the mass transfer coefficients were quantitatively and qualitatively clarified in the range of 50 to 1000 of inlet Reynolds numbers, 0 to 0.5 of inlet oxygen mass fraction and 800 to 1600degC of temperature. (author)
DEFF Research Database (Denmark)
Ratkovich, Nicolas Rios; Berube, P.R.; Nopens, I.
2011-01-01
by the gas flow. It was noted that coalescence of bubbles affects the MTH. Coalescence increased the “width” of the peaks (i.e. the estimate of the variability of the mass transfer coefficient) and the height of the peak (i.e. amount of time that a mass transfer coefficient of a given value is maintained......). A semi-empirical relationship based on the Lévêque relationship for the Sherwood number (mass transfer coefficient) was formulated for the laminar regime. A test case comparison between water and activated sludge was performed based on full-scale airlift MBR operational conditions. It was found...
Magnetic resonance imaging of flow and mass transfer in electrohydrodynamic liquid bridges
Wexler, Adam D.; Drusová, Sandra; Fuchs, Elmar C.; Woisetschläger, Jakob; Reiter, Gert; Fuchsjäger, Michael; Reiter, Ursula
2017-01-01
Abstract: Here, we report on the feasibility and use of magnetic resonance imaging-based methods to the study of electrohydrodynamic (EHD) liquid bridges. High-speed tomographic recordings through the longitudinal axis of water bridges were used to characterize the mass transfer dynamics, mixing,
Li, Chunqing; Tie, Xiaobo; Liang, Kai; Ji, Chanjuan
2016-01-01
After conducting the intensive research on the distribution of fluid's velocity and biochemical reactions in the membrane bioreactor (MBR), this paper introduces the use of the mass-transfer differential equation to simulate the distribution of the chemical oxygen demand (COD) concentration in MBR membrane pool. The solutions are as follows: first, use computational fluid dynamics to establish a flow control equation model of the fluid in MBR membrane pool; second, calculate this model by adopting direct numerical simulation to get the velocity field of the fluid in membrane pool; third, combine the data of velocity field to establish mass-transfer differential equation model for the concentration field in MBR membrane pool, and use Seidel iteration method to solve the equation model; last but not least, substitute the real factory data into the velocity and concentration field model to calculate simulation results, and use visualization software Tecplot to display the results. Finally by analyzing the nephogram of COD concentration distribution, it can be found that the simulation result conforms the distribution rule of the COD's concentration in real membrane pool, and the mass-transfer phenomenon can be affected by the velocity field of the fluid in membrane pool. The simulation results of this paper have certain reference value for the design optimization of the real MBR system.
Research on heat and mass transfer model for passive containment cooling system
International Nuclear Information System (INIS)
Jiang Xiaowei; Yu Hongxing; Sun Yufa; Huang Daishun
2013-01-01
Different with the traditional dry style containment design without external cooling, the PCCS design increased the temperature difference between the wall and the containment atmosphere significantly, and also the absolute temperature of the containment surfaces will be lower, affecting properties relevant in the condensation process. A research on the heat and mass transfer model has been done in this paper, especially the improvement on the condensation and evaporation model in the presence of noncondensable gases. Firstly, the Peterson's diffusion layer model was proved to equivalent to the stagnant film model adopted by CONTAIN code using the Clausius-Clapeyron equation, then a factor which can be used to stagnant film model was derived from the comparison between the Y.Liao's generalized diffusion layer model and the Peterson's diffusion layer model. Finally, the model in CONTAIN code used to compute the condensation and evaporation mass flux was modified using the factor, and the Wisconsin condensation tests and Westinghouse film evaporation on heated plate tests were simulated which had proved the improved model can predict more closer value of the heat and mass transfer coefficient to experimental value than original model. (authors)
Influence of mass transfer resistance on overall nitrate removal rate in upflow sludge bed reactors.
Ting, Wen-Huei; Huang, Ju-Sheng
2006-09-01
A kinetic model with intrinsic reaction kinetics and a simplified model with apparent reaction kinetics for denitrification in upflow sludge bed (USB) reactors were proposed. USB-reactor performance data with and without sludge wasting were also obtained for model verification. An independent batch study showed that the apparent kinetic constants k' did not differ from the intrinsic k but the apparent Ks' was significantly larger than the intrinsic Ks suggesting that the intra-granule mass transfer resistance can be modeled by changes in Ks. Calculations of the overall effectiveness factor, Thiele modulus, and Biot number combined with parametric sensitivity analysis showed that the influence of internal mass transfer resistance on the overall nitrate removal rate in USB reactors is more significant than the external mass transfer resistance. The simulated residual nitrate concentrations using the simplified model were in good agreement with the experimental data; the simulated results using the simplified model were also close to those using the kinetic model. Accordingly, the simplified model adequately described the overall nitrate removal rate and can be used for process design.
DEFF Research Database (Denmark)
Antola, M.; Di Chiara, S.; Sannino, F.
2011-01-01
We introduce novel extensions of the Standard Model featuring a supersymmetric technicolor sector (supertechnicolor). As the first minimal conformal supertechnicolor model we consider N=4 Super Yang-Mills which breaks to N=1 via the electroweak interactions. This is a well defined, economical......, between unparticle physics and Minimal Walking Technicolor. We consider also other N =1 extensions of the Minimal Walking Technicolor model. The new models allow all the standard model matter fields to acquire a mass....
International Nuclear Information System (INIS)
Agarwal, B.
2012-01-01
Proton Transfer Reaction Mass Spectrometry (PTR-MS) is a mass spectrometric technique based on chemical ionization, which provides very rapid measurements (within seconds) of volatile organic compounds in air, usually without special sample preparation, and with a very low detection limit. The detection and study of product ion patterns of threat agents such as explosives and drugs and some major environmental pollutants (isocyanates and polychlorinated biphenyls (PCBs)) is explored in detail here using PTR-MS, specifically Proton Transfer Reaction Time-of-Flight Mass Spectrometry (PTR-TOF-MS). The proton transfer reaction (PTR) principle works on the detection of the compound in the vapor phase. For some compounds, which have extremely low vapor pressures, both sample and inlet line heating were needed. Generally, the protonated parent molecule (MH+) is found to be the dominant product ion, which therefore provides us with a higher level of confidence in the assignment of a trace compound. However, for several compounds, dissociative proton transfer can occur at various degrees resulting in other product ions. Analysis of other compounds, such as the presence of taggants and impurities were carried out, and in certain compounds unusual E/N anomalies were discovered (E/N is an instrumental set of parameters, where E is the electric field strength and N is the number density). Head space measurements above four different drinks (plain water, tea, red wine and white wine) spiked with four different 'date rape' drugs were also conducted. (author)
Mass transfer coefficient factor in pipe bend - 3 D CFD analysis
International Nuclear Information System (INIS)
Prasad, Mahendra; Gaikwad, Avinash J.; Madasamy, P.; Krishnamohan, T.V.; Velumurugan, S.; Sridharan, Arunkumar; Parida, Smrutiranjan
2015-01-01
In power industries Flow Accelerated Corrosion (FAC) has been a concern for pipe wall thinning where high velocity fluid at elevated temperatures is used. Even straight pipes are found to have non uniform corrosion and this is enhanced in junctions such as bends, orifices etc. Mass transfer coefficient (MTC) which defines the amount of corrosion changes from its value in straight pipe (with same fluid parameters) for flow in bends, orifice etc due to changes in velocity profile in axial direction. In this paper, 3 D computational fluid dynamics (CFD) simulation is carried out for an experiment on 58° bend angle and 2D bend radius circular carbon steel pipe carrying water at 120°C under neutral pH conditions. The turbulent model K-ω with shear stress transport was used for this purpose. The mass transfer boundary layer (MTBL) thickness δ mtbl depends on Schmidt number (Sc), as δ mtbl ∼ δ h /(Sc 1/3 ). MTBL is significantly smaller than hydrodynamic boundary layer δ h for large Sc, hence boundary layer meshing was carried out deep into δ mtbl . Uniform velocity was applied at the inlet. The flow velocity was 3 m/s at room temperature while the experimental fluid velocity was 7 m/s. Lower value of fluid velocity is chosen due to the limitations of grid size since it depends inversely on fluid velocity. The ratio of MTC in bend to straight pipe is not strongly dependent on Sc. CFD simulation at lower temperature is sufficient to get approximate MTC in bends. The ratio of the mass transfer coefficient at some locations in bend to the straight pipe coefficient (MTCR) is determined through simulation. The MTC increased in the extrados of the bend towards the outlet. (author)
Numerical Problems and Agent-Based Models for a Mass Transfer Course
Murthi, Manohar; Shea, Lonnie D.; Snurr, Randall Q.
2009-01-01
Problems requiring numerical solutions of differential equations or the use of agent-based modeling are presented for use in a course on mass transfer. These problems were solved using the popular technical computing language MATLABTM. Students were introduced to MATLAB via a problem with an analytical solution. A more complex problem to which no…
Directory of Open Access Journals (Sweden)
Shahrouz Mohagheghian
2018-04-01
Full Text Available Vertical vibration is known to cause bubble breakup, clustering and retardation in gas-liquid systems. In a bubble column, vibration increases the mass transfer ratio by increasing the residence time and phase interfacial area through introducing kinetic buoyancy force (Bjerknes effect and bubble breakup. Previous studies have explored the effect of vibration frequency (f, but minimal effort has focused on the effect of amplitude (A on mass transfer intensification. Thus, the current work experimentally examines bubble size, void fraction, and mass transfer in a bubble column under relatively high amplitude vibration (1.5 mm < A <9.5 mm over a frequency range of 7.5–22.5 Hz. Results of the present work were compared with past studies. The maximum stable bubble size under vibration was scaled using Hinze theory for breakage. Results of this work indicate that vibration frequency exhibits local maxima in both mass transfer and void fraction. Moreover, an optimum amplitude that is independent of vibration frequency was found for mass transfer enhancements. Finally, this work suggests physics-based models to predict void fraction and mass transfer in a vibrating bubble column.
The interaction between liquid motion and mass transfer induced by single rising bubble via PIV/LIE
International Nuclear Information System (INIS)
Yoshimoto, Kenjo; Yamamoto, Manabu; Sone, Daiji; Saito, Takayuki
2009-01-01
Deep understanding of gas-liquid two phase flows is essential for safe operation and high efficiency of nuclear reactors, chemical reactors and so on. In this study, we focus on the process of mass transfer induced by a single rising bubble. The mass transfer process of a zigzag ascending single bubble is investigated via LIF (Laser Induced Fluorescence) and PIV (Particle Image Velocimetry). From these results, we discuss the relationship between the mass transfer and the surrounding liquid motion of the single bubble. We examined single CO 2 -bubbles of 2-3 mm in equivalent diameter, which shows zigzagging motion in rest water. To directly visualize the dynamic mass transfer of CO 2 from the bubble surface to the surrounding liquid, HPTS (8-hydroxypyrene-1, 3, 6-trisulfonic acid) was used as a fluorescent substance for LIF. From LIF results, it was observed that the CO 2 -rich regions were spread by advective flow in the rest water as horseshoe-like vortices. From LIF results combined with the PIV results, it was observed that the horseshoe-like vortices were transported by the fast upward flow (buoyancy driven flow). Especially, in the case of a larger-diameter bubble with large shape oscillations, the high turbulence intensity (in a strict sense, fluctuation intensity of the liquid-phase velocity) was observed. The CO 2 -rich regions spread over a wide range by the strong flow. As a result, it is considered that the high turbulence intensity which was caused by the shape oscillations enhances the mass transportation from the bubble to the surrounding liquid. (author)
Study of water mass transfer dynamics in frescoes by dielectric spectroscopy
International Nuclear Information System (INIS)
Olmi, R.; Riminesi, C.
2008-01-01
The knowledge of moisture content (M C) is essential for determining the state of preservation of various types of hand-work: from building materials such as bricks and concrete, to objects of artistic value, in particular frescoes and mural paintings. In all above, moisture is the primary source of damages, as it affects the durability of porous materials. Dielectric properties of porous materials are strongly affected by the presence of water, suggesting dielectric spectroscopy as a suitable non-invasive diagnostic technique. The development of a quantitative relationship between M C and permittivity requires to investigate the dynamics of water mass transfer in porous media, and to determine its effect on the dielectric properties. In this paper a coupled mass transfer/dielectric problem is introduced and solved numerically, based on a finite element model. Results are compared to experimental dielectric measurements performed on plaster samples by the open coaxial method. The application of the dielectric technique to frescoes monitoring is proposed, showing the results obtained is an on-site study.
Aerosol formation from heat and mass transfer in vapour-gas mixtures
International Nuclear Information System (INIS)
Clement, C.F.
1985-01-01
Heat and mass transfer equations and their coupling to the equation for the aerosol size distribution are examined for mixtures in which pressure changes are slow. Specific results in terms of Cn (the condensation number) and Le (the Lewis number - the ratio of the relative rates of evaporation and condensation) are obtained for the proportion of vapour condensing as a aerosol during the cooling and heating of a mixture in a well-mixed cavity. The assumption of allowing no supersaturations, the validity of which is examined, is shown to lead to maximum aerosol formation. For water vapour-air mixtures predictions are made as to temperature regions in which aerosols will evaporate or not form in cooling processes. The results are also qualitatively applied to some atmospheric effects as well as to water aerosols formed in the containment of a pressurized water reactor following a possible accident. In this context, the present conclusion that the whereabouts of vapour condensation is controlled by heat and mass transfer, contrasts with previous assumptions that the controlling factor is relative surface areas. (U.K.)
Nadi, Fatemeh; Tzempelikos, Dimitrios
2018-01-01
In this work, apples of cv. Golden Delicious were cut into slices that were 5 and 7 mm thick and then vacuum dried at 50, 60 and 70 °C and pressure of 0.02 bar. The thin layer model drying kinetics was studied, and mass transfer properties, specifically effective moisture diffusivity and convective mass transfer coefficient, were evaluated using the Fick's equation of diffusion. Also, thermodynamic parameters of the process, i.e. enthalpy (ΔH), entropy (ΔS) and Gibbs free energy (ΔG), were determined. Colour properties were evaluated as one of the important indicators of food quality and marketability. Determination of mass transfer parameters and thermodynamic properties of vacuum dried apple slices has not been discussed much in the literature. In conclusion, the Nadi's model fitted best the observed data that represent the drying process. Thermodynamic properties were determined based on the dependence of the drying constant of the Henderson and Pabis model on temperature, and it was concluded that the variation in drying kinetics depends on the energy contribution of the surrounding environment. The enthalpy and entropy diminished, while the Gibbs free energy increased with the increase of the temperature of drying; therefore, it was possible to verify that variation in the diffusion process in the apple during drying depends on energetic contributions of the environment. The obtained results showed that diffusivity increased for 69%, while the mass transfer coefficient increase was even higher, 75%, at the variation of temperature of 20 °C. The increase in the dimensionless Biot number was 20%.
Uranium and zirconium mass transfer testing of 5.5-cm-diam centrifugal contactors
International Nuclear Information System (INIS)
DeMuth, S.F.; Randolph, J.D.
1988-01-01
As part of the Consolidated Fuel Reprocessing Program of the Oak Ridge National Laboratory, compact centrifugal contacts were designed and prototypes build for the Breeder Reprocessing Engineering Test (BRET) facility with a throughput capacity of 0.1 t/d of heavy metals. While the construction of BRET has been put on hold indefinitely, development of the 5.5-cm-diam centrifugal contactors has advanced due to the contactor's broad applicability in other areas of fuel reprocessing and other liquid-liquid extraction. Due to the short residence time of the process fluids in a centrifugal contactor, it was necessary to measure the mass transfer efficiency for a typical process flowsheet. This was done with depleted uranium and 91 Zr. The results of mass transfer tests with uranium and zirconium are reported in this paper
International Nuclear Information System (INIS)
Yoo, Jae Hyung; Lee, Byung Jik; Shim, Joon Bo; Kim, Eung Ho
2007-01-01
It was intended in this study to investigate the effects of various parameters on the chemical reaction or mass transfer yield in a tubular-type nuclear waste treatment equipment. Since such equipment. as a tubular reactor, multistage solvent extractor, and adsorption column, accompany chemical reaction or mass transfer along the fluid-flowing direction, mathematical modeling for each equipment was carried out first. Then their behaviors of the chemical reaction or mass transfer were predicted through computer simulations. The inherent major parameters for each equipment were chosen and their sensitivities affecting the reaction or mass transfer yield were analyzed. For the tubular reactor, the effects of axial diffusion coefficient and reaction rate constant on the reaction yield were investigated. As for the multistage solvent extractor, the back mixing of continuous phase and the distribution coefficient between fluid and solvent were considered as the major parameters affecting the extraction yield as well as concentration profiles throughout the axial direction of the extractor. For the adsorption column, the equilibrium constant between fluid and adsorbent surface. and the overall mass transfer coefficient between the two phases were taken as the major factors that affect the adsorption rate
International Nuclear Information System (INIS)
Nigmatulin, B.I.; Kroshilin, A.E.; Kroshilin, V.E.
1979-01-01
The effect of interaction between inclusions in a gas-liquid mixture on interphase heat and mass transfer is analyzed. It is taken into account that inclusions (bubbles or drops) are not in a pure carrier phase, but in a disperse medium, mean properties of which are determined by the presence of other inclusions in it and by a temperature field around them. The consideration is carried out in the framework of two model of monodisperse mixture, i.e. that with a chaotic distribution of inclusions, and that with a regular distribution, when the distance between centers of inclusions is fixed. The correlation functions method is shown to be effective for the both models. Mean temperature fields around inclusions are determined along with the intensity of interphase heat and mass transfer. The dependences obtained are in a satisfactory agreement with experimental data. The dependence of interphase heat and mass transfer on the structure of disperse mixture is analyzed
Applying rotary jet heads for mixing and mass transfer in a forced recirculation tank reactor system
DEFF Research Database (Denmark)
Nordkvist, Mikkel; Grotkjær, Thomas; Hummer, J.S.
2003-01-01
or an external loop.In this study, we determine mixing times in water and CMC solutions and oxygen mass transfer coefficients in water for a tank reactor system where a small fraction of the total liquid volume is rapidly circulated through an external loop and injected through the nozzles of rotary jet heads....... The system has a very simple design with no internal baffles or heat exchange area, and between batches the rotary jet heads are used for cleaning in place.Mixing time decreases and mass transfer increases with increasing circulation flow rate. For nozzle diameters between 5.5 and 10 mm and with one or two...... rotary jet heads, it is shown that a remarkable saving in power input for a fixed mixing time or mass transfer coefficient can be obtained by using a large nozzle diameter and two rather than one rotary jet heads.At the experimental conditions of the study the system is scaleable by simple formulas...
Investigation of wall mass transfer characteristics downstream of an orifice
International Nuclear Information System (INIS)
El-Gammal, M.; Ahmed, W.H.; Ching, C.Y.
2012-01-01
Highlights: ► Numerical simulations were performed for the mass transfer downstream of an orifice. ► The Low Reynolds Number K-ε turbulence model was used. ► The numerical results were in good agreement with existing experimental results. ► The maximum Sherwood number downstream of the orifice was significantly affected by the Reynolds number. ► The Sherwood number profile was well correlated with the turbulence kinetic energy profile close to the wall. - Abstract: Numerical simulations were performed to determine the effect of Reynolds number and orifice to pipe diameter ratio (d o /d) on the wall mass transfer rate downstream of an orifice. The simulations were performed for d o /d of 0.475 for Reynolds number up to 70,000. The effect of d o /d was determined by performing simulations at a Reynolds number of 70,000 for d o /d of 0.375, 0.475 and 0.575. The momentum and mass transport equations were solved using the Low Reynolds Number (LRN) K-ε turbulence model. The Sherwood number (Sh) profile downstream of the orifice was in relatively good agreement with existing experimental results. The Sh increases sharply downstream of the orifice, reaching a maximum within 1–2 diameters downstream of the orifice, before relaxing back to the fully developed pipe flow value. The Sh number well downstream of the orifice was in good agreement with results for fully developed pipe flow estimated from the correlation of . The peak Sh numbers from the simulations were higher than that predicted from and .
A multi-fluid model to simulate heat and mass transfer in a PEM fuel cell
DEFF Research Database (Denmark)
Berning, Torsten; Odgaard, Madeleine; Kær, Søren Knudsen
2011-01-01
This article summarizes a multi-phase model of a polymer electrolyte membrane fuel cell based on the formerly commercial CFD code CFX-4. It is three-dimensional in nature and includes multiphase heat and mass transfer in porous media. An overview is given and some numerical issues are discussed...... heat and mass transfer properties are superior. Another important aspect of this study is the wetting status of the electrolyte menbrane and the effective drag of water through the menbrane, which indicates what fraction of the product water created at the cathode side diffuses through the membrane...
Ducote, M J; Prakash, S; Pettis, G S
2000-12-01
Efficient interbacterial transfer of streptomycete plasmid pIJ101 requires the pIJ101 tra gene, as well as a cis-acting plasmid function known as clt. Here we show that the minimal pIJ101 clt locus consists of a sequence no greater than 54 bp in size that includes essential inverted-repeat and direct-repeat sequences and is located in close proximity to the 3' end of the korB regulatory gene. Evidence that sequences extending beyond the minimal locus and into the korB open reading frame influence clt transfer function and demonstration that clt-korB sequences are intrinsically curved raise the possibility that higher-order structuring of DNA and protein within this plasmid region may be an inherent feature of efficient pIJ101 transfer.
Heat and Mass Transfer at Hot Surface Ignition of Coal Particle
Glushkov Dmitrii O.; Kosintsev Andrey. G.; Shlegel Nikita E.; Vershinina Ksenia Yu.
2015-01-01
This paper describes the experimental investigations of the characteristics of heat and mass transfer during the conductive heating of a coal particle. We have established the boundary conditions of combustion initiation, and the conditions of thermal decomposition and solid fuel particles decay, characterized by the temperature of a heat source, and the duration of the respective stages.
Mass-transfer in extraction and reextraction as a single-stage process
International Nuclear Information System (INIS)
Rodriguez del Cerro, M.; Trilleros, J.A.; Otero de la Gandara, J.L.
1987-01-01
The rate of mass transfer between water and naftenic acid and threebutilphosphate in kerosen are studied in the two possibilities to or from water. The two insoluble phases are brought in to intimate contact with dispersed phase droplets, in a single-stage process. The evolution of the equilibrium distribution of solute is taken in consideration. (author)
Mass and heat transfer at the outer surface of helical coils under single and two phase flow
International Nuclear Information System (INIS)
Abdel-Aziz, M.H.; Nirdosh, I.; Sedahmed, G.H.
2016-01-01
Highlights: • The work aims to develop reactors which need rapid temperature control. • Mass and heat transfer at the outer surface of helical coils was studied experimentally. • The experiments were conducted under gas sparing, single and two phase flow. • Variables were helical tube diameter, physical properties, and gas and liquid velocity. • Results verification in terms of natural convection and surface renewal mechanism was explained. - Abstract: The mass transfer behavior of the outer surface of vertical helical coil was studied by the electrochemical technique under single phase flow, gas sparging and two phase flow. Variables studied were helical tube diameter, physical properties of the solution, solution velocity and superficial gas velocity. The mass transfer data were correlated by dimensionless equations. Mass transfer enhancement ratio in case of two phase flow ranged from 1.1 to 4.9 compared to single phase flow. Implication of the results for the design and operation of helical coil reactors used to conduct L–S exothermic diffusion controlled reactions which need rapid temperature control were outlined. In this case the inner coil surface will act as a cooler while the outer surface will act a reaction surface. Immobilized enzyme catalyzed biochemical reactions where heat sensitive materials may be involved represent an example for the reactions which can employ the helical coil reactor. Also the importance of the results in the design of and operation of diffusion controlled membrane processes which employ helical coil membrane was noted. In view of the analogy between heat and mass transfer the possibility of using the results in the design and operation of helical coil heat exchangers was highlighted.
Energy Technology Data Exchange (ETDEWEB)
Marquard, P.; Mihaila, L.; Steinhauser, M. [Karlsruhe Univ. (T.H.) (Germany). Inst. fuer Theoretische Teilchenphysik; Piclum, J.H. [Karlsruhe Univ. (T.H.) (Germany). Inst. fuer Theoretische Teilchenphysik]|[Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik
2007-02-15
We compute the relation between the pole quark mass and the minimally subtracted quark mass in the framework of QCD applying dimensional reduction as a regularization scheme. Special emphasis is put on the evanescent couplings and the renormalization of the {epsilon}-scalar mass. As a by-product we obtain the three-loop on-shell renormalization constants Z{sub m}{sup OS} and Z{sub 2}{sup OS} in dimensional regularization and thus provide the first independent check of the analytical results computed several years ago. (orig.)
Hahn, T; Heinemeyer, S; Hollik, W; Rzehak, H; Weiglein, G
2014-04-11
For the interpretation of the signal discovered in the Higgs searches at the LHC it will be crucial in particular to discriminate between the minimal Higgs sector realized in the standard model (SM) and its most commonly studied extension, the minimal supersymmetric standard model (MSSM). The measured mass value, having already reached the level of a precision observable with an experimental accuracy of about 500 MeV, plays an important role in this context. In the MSSM the mass of the light CP-even Higgs boson, Mh, can directly be predicted from the other parameters of the model. The accuracy of this prediction should at least match the one of the experimental result. The relatively high mass value of about 126 GeV has led to many investigations where the scalar top quarks are in the multi-TeV range. We improve the prediction for Mh in the MSSM by combining the existing fixed-order result, comprising the full one-loop and leading and subleading two-loop corrections, with a resummation of the leading and subleading logarithmic contributions from the scalar top sector to all orders. In this way for the first time a high-precision prediction for the mass of the light CP-even Higgs boson in the MSSM is possible all the way up to the multi-TeV region of the relevant supersymmetric particles. The results are included in the code FEYNHIGGS.
Kim, Nae-Hyun
2016-12-01
R-410A condensation heat transfer and pressure drop data are provided for a 7.0 mm O.D. microfin tube at low mass fluxes (50-250 kg/m2 s). The heat transfer coefficient of the microfin tube shows a minimum behavior with the mass flux. At a low mass flux, where flow pattern is stratified, condensation induced by surface tension by microfins overwhelms condensation induced by shear, and the heat transfer coefficient decreases as mass flux increases. At a high mass flux, where flow pattern is annular, condensation induced by shear governs the heat transfer, and the heat transfer coefficient increases as mass flux increases. The pressure drop of the microfin tube is larger than that of the smooth tube at the annular flow regime. On the contrary, the pressure drop of the smooth tube is larger than that of the microfin tube at the stratified flow regime.
Smith, K.E.C.; Thullner, M.; Wick, L.Y.; Harms, H.
2011-01-01
The hypothesis that dissolved organic carbon (DOC) enhances the mass transfer of hydrophobic organic compounds from nonaqueous phase liquids (NAPLs) into the aqueous phase above that attributable to dissolved molecular diffusion alone was tested. In controlled experiments, mass transfer rates of
International Nuclear Information System (INIS)
Li, Xiu-Wei; Zhang, Xiao-Song; Chen, Qing
2015-01-01
Highlights: • Experimental research has been made on the membrane air-conditioning system. • We develop mass transfer models for the membrane regeneration process. • The paper exposes the actual performance of the system. • Increase of membrane pairs improves the performance. - Abstract: Absorption air-conditioning system has great advantages in energy conservation and environmental protection. To improve the performance of the traditional system, the membrane regeneration absorption system was proposed. Its COP could approach 6 by regenerating absorbent solution with the ion exchange membranes. However, the theoretical conclusion has not been supported by the experiment. This paper presents the experimental research of the membrane regeneration process. It has investigated the mass transfer process, energy efficiency and actual performance under different working conditions. Based on that, a mass transfer model has been developed and the influences of some key parameters have been exposed. It found the regeneration performance is mainly influenced by the current intensity. The calculation results with the model agree well the experimental data. The actual efficiency was lower than 50%, caused by energy loss in heat and electrochemical reactions. The actual COP is between 1 and 3, lower current intensity and more membrane pairs could improve it.
Experimental assessment of heat and mass transfer of modular nozzles of cooling towers
Merentsov, N. A.; Lebedev, V. N.; Golovanchikov, A. B.; Balashov, V. A.; Nefed'eva, E. E.
2018-01-01
Data of experimental study of hydrodynamics, heat and mass transfer of modular nozzles of cooling towers and some comparative characteristics of the packed device with nozzles, which have wide industrial application, are given in the article.
Photometric Analysis and Modeling of Five Mass-Transferring Binary Systems
Geist, Emily; Beaky, Matthew; Jamison, Kate
2018-01-01
In overcontact eclipsing binary systems, both stellar components have overfilled their Roche lobes, resulting in a dumbbell-shaped shared envelope. Mass transfer is common in overcontact binaries, which can be observed as a slow change on the rotation period of the system.We studied five overcontact eclipsing binary systems with evidence of period change, and thus likely mass transfer between the components, identified by Nelson (2014): V0579 Lyr, KN Vul, V0406 Lyr, V2240 Cyg, and MS Her. We used the 31-inch NURO telescope at Lowell Observatory in Flagstaff, Arizona to obtain images in B,V,R, and I filters for V0579 Lyr, and the 16-inch Meade LX200GPS telescope with attached SBIG ST-8XME CCD camera at Juniata College in Huntingdon, Pennsylvania to image KN Vul, V0406 Lyr, V2240 Cyg, and MS Her, also in B,V,R, and I.After data reduction, we created light curves for each of the systems and modeled the eclipsing binaries using the BinaryMaker3 and PHOEBE programs to determine their fundamental physical parameters for the first time. Complete light curves and preliminary models for each of these neglected eclipsing binary systems will be presented.
Heat and mass transfers between two stratified liquid phases in a bubbly flow
International Nuclear Information System (INIS)
Lapuerta, C.
2006-10-01
During an hypothetical major accident in a pressurized water reactor, the deterioration of the core can produce a stratified pool crossed by a bubbly flow. This latter strongly impacts the heat transfers, whose intensities are crucial in the progression of the accident. In this context, this work is devoted to the diffuse interface modelling for the study of an-isothermal incompressible flows, composed of three immiscible components, with no phase change. In the diffuse interface methods, the system evolution is driven by the minimization of a free energy. The originality of our approach, derived from the Cahn-Hilliard model, is based on the particular form of the energy we proposed, which enables to have an algebraically and dynamically consistent model, in the following sense: on the one hand, the triphasic free energy is equal to the diphasic one when only two phases are present; on the other, if a phase is not initially present then it will not appear during system evolution, this last property being stable with respect to numerical errors. The existence and the uniqueness of weak and strong solutions are proved in two and three dimensions as well as a stability result for metastable states. The modelling of an an-isothermal three phase flow is further accomplished by coupling the Cahn-Hilliard equations with the energy balance and Navier-Stokes equations where surface tensions are taken into account through volume capillary forces. These equations are discretized in time and space in order to preserve properties of continuous model (volume conservation, energy estimate). Different numerical results are given, from the validation case of the lens spreading between two phases, to the study of the heat and mass transfers through a liquid/liquid interface crossed by a single bubble or a series of bubbles. (author)
Heat and mass transfer from the mantle: heat flow and He-isotope constraints
Directory of Open Access Journals (Sweden)
B. G. Polyak
2005-06-01
Full Text Available Terrestrial heat flow density, q, is inversely correlated with the age, t, of tectono-magmatic activity in the Earth's crust (Polyak and Smirnov, 1966; etc.. «Heat flow-age dependence» indicates unknown temporal heat sources in the interior considered a priori as the mantle-derived diapirs. The validity of this hypothesis is demonstrated by studying the helium isotope ratio, 3He/4He = R, in subsurface fluids. This study discovered the positive correlation between the regionally averaged (background estimations of R- and q-values (Polyak et al., 1979a. Such a correlation manifests itself in both pan-regional scales (Norhtern Eurasia and separate regions, e.g., Japan (Sano et al., 1982, Eger Graben (Polyak et al., 1985 Eastern China rifts (Du, 1992, Southern Italy (Italiano et al., 2000, and elsewhere. The R-q relation indicates a coupled heat and mass transfer from the mantle into the crust. From considerations of heat-mass budget this transfer can be provided by the flux consisting of silicate matter rather than He or other volatiles. This conclusion is confirmed by the correlation between 3He/ 4He and 87Sr/86Sr ratios in the products of the volcanic and hydrothermal activity in Italy (Polyak et al., 1979b; Parello et al., 2000 and other places. Migration of any substance through geotemperature field transports thermal energy accumulated within this substance, i.e. represents heat and mass transfer. Therefore, only the coupled analysis of both material and energy aspects of this transfer makes it possible to characterise the process adequately and to decipher an origin of terrestrial heat flow observed in upper parts of the earth crust. An attempt of such kind is made in this paper.
Nogueira, Bruno L; Pérez, Julio; van Loosdrecht, Mark C M; Secchi, Argimiro R; Dezotti, Márcia; Biscaia, Evaristo C
2015-09-01
In moving bed biofilm reactors (MBBR), the removal of pollutants from wastewater is due to the substrate consumption by bacteria attached on suspended carriers. As a biofilm process, the substrates are transported from the bulk phase to the biofilm passing through a mass transfer resistance layer. This study proposes a methodology to determine the external mass transfer coefficient and identify the influence of the mixing intensity on the conversion process in-situ in MBBR systems. The method allows the determination of the external mass transfer coefficient in the reactor, which is a major advantage when compared to the previous methods that require mimicking hydrodynamics of the reactor in a flow chamber or in a separate vessel. The proposed methodology was evaluated in an aerobic lab-scale system operating with COD removal and nitrification. The impact of the mixing intensity on the conversion rates for ammonium and COD was tested individually. When comparing the effect of mixing intensity on the removal rates of COD and ammonium, a higher apparent external mass transfer resistance was found for ammonium. For the used aeration intensities, the external mass transfer coefficient for ammonium oxidation was ranging from 0.68 to 13.50 m d(-1) and for COD removal 2.9 to 22.4 m d(-1). The lower coefficient range for ammonium oxidation is likely related to the location of nitrifiers deeper in the biofilm. The measurement of external mass transfer rates in MBBR will help in better design and evaluation of MBBR system-based technologies. Copyright © 2015 Elsevier Ltd. All rights reserved.
Regenerator optimization of a Closed Brayton Cycle via entropy generation minimization
International Nuclear Information System (INIS)
Araújo, Élvis Falcão de; Ribeiro, Guilherme Borges; Guimarães, Lamartine N. F.
2017-01-01
This paper aims the numerical study of the heat transfer and fluid flow of a Closed Brayton Cycle (CBC) regenerator that is part of TERRA microreactor. This regenerator consists in a cross flow heat exchanger, where heat transfer occurs between internal fluid flow in radial tubes and external fluid flow passing perpendicularly to the tubes, which are disposed in a symmetrical cylindrical set where the number of tubes in the axial and radial directions can vary. In the simulations, mass flow inlet is varied for a fixed geometry. The fluid flow solution is provided by a commercial CFD solver and the entropy generation number calculation is later computed for optimization purposes. As a result, the entropy minimization method provides the regenerator configuration that enables the highest energy conversion efficiency. (author)
Regenerator optimization of a Closed Brayton Cycle via entropy generation minimization
Energy Technology Data Exchange (ETDEWEB)
Araújo, Élvis Falcão de; Ribeiro, Guilherme Borges; Guimarães, Lamartine N. F., E-mail: falcao@ieav.cta.br, E-mail: gbribeiro@ieav.cta.br, E-mail: guimarae@ieav.cta.br [Instituto de Estudos Avançacados (IEAv), São José dos Campos, SP (Brazil). Div. de Energia Nuclear
2017-07-01
This paper aims the numerical study of the heat transfer and fluid flow of a Closed Brayton Cycle (CBC) regenerator that is part of TERRA microreactor. This regenerator consists in a cross flow heat exchanger, where heat transfer occurs between internal fluid flow in radial tubes and external fluid flow passing perpendicularly to the tubes, which are disposed in a symmetrical cylindrical set where the number of tubes in the axial and radial directions can vary. In the simulations, mass flow inlet is varied for a fixed geometry. The fluid flow solution is provided by a commercial CFD solver and the entropy generation number calculation is later computed for optimization purposes. As a result, the entropy minimization method provides the regenerator configuration that enables the highest energy conversion efficiency. (author)
Irradiation of a barrier film: analysis of some mass transfer aspects
International Nuclear Information System (INIS)
Deschenes, L.; Arbour, A.; Brunet, F.; Court, M.A.; Doyon, G.J.; Fortin, J.; Rodrigue, N.
1995-01-01
Irradiation of a Nylon/PVDC/EVA barrier film caused changes in mass transfers of the packaging material. Sensory evaluation of irradiated water indicated development of off-odours and taints, even at 1 kGy. This behaviour differed with the irradiation source (gamma or beta). Aldehydes and polymer hydrocarbons were involved in the development of irradiation tainting from packaging film. (Author)
Vas Bhat, R.D.; Kuipers, J.A.M.; Versteeg, G.F.
2000-01-01
An absorption model to study gas–liquid mass transfer accompanied by reversible two-step reactions in the liquid phase has been presented. This model has been used to determine mass transfer rates, enhancement factors and concentration profiles over a wide range of process conditions. Although
International Nuclear Information System (INIS)
Janecky, D.R.
1988-01-01
A computational modeling code (EQPSreverse arrowS) has been developed to examine sulfur isotopic distribution pathways coupled with calculations of chemical mass transfer pathways. A post processor approach to EQ6 calculations was chosen so that a variety of isotopic pathways could be examined for each reaction pathway. Two types of major bounding conditions were implemented: (1) equilibrium isotopic exchange between sulfate and sulfide species or exchange only accompanying chemical reduction and oxidation events, and (2) existence or lack of isotopic exchange between solution species and precipitated minerals, parallel to the open and closed chemical system formulations of chemical mass transfer modeling codes. All of the chemical data necessary to explicitly calculate isotopic distribution pathways is generated by most mass transfer modeling codes and can be input to the EQPS code. Routines are built in to directly handle EQ6 tabular files. Chemical reaction models of seafloor hydrothermal vent processes and accompanying sulfur isotopic distribution pathways illustrate the capabilities of coupling EQPSreverse arrowS with EQ6 calculations, including the extent of differences that can exist due to the isotopic bounding condition assumptions described above. 11 refs., 2 figs
Fukuda, Makoto; Yoshimura, Kengo; Namekawa, Koki; Sakai, Kiyotaka
2017-06-01
The objective of the present study is to evaluate the effect of filtration coefficient and internal filtration on dialysis fluid flow and mass transfer coefficient in dialyzers using dimensionless mass transfer correlation equations. Aqueous solution of vitamin B 12 clearances were obtained for REXEED-15L as a low flux dialyzer, and APS-15EA and APS-15UA as high flux dialyzers. All the other design specifications were identical for these dialyzers except for filtration coefficient. The overall mass transfer coefficient was calculated, moreover, the exponents of Reynolds number (Re) and film mass transfer coefficient of the dialysis-side fluid (k D ) for each flow rate were derived from the Wilson plot and dimensionless correlation equation. The exponents of Re were 0.4 for the low flux dialyzer whereas 0.5 for the high flux dialyzers. Dialysis fluid of the low flux dialyzer was close to laminar flow because of its low filtration coefficient. On the other hand, dialysis fluid of the high flux dialyzers was assumed to be orthogonal flow. Higher filtration coefficient was associated with higher k D influenced by mass transfer rate through diffusion and internal filtration. Higher filtration coefficient of dialyzers and internal filtration affect orthogonal flow of dialysis fluid.
Mass transfer in porous media with heterogeneous chemical reaction
Directory of Open Access Journals (Sweden)
Souza S.M.A.G.Ulson de
2003-01-01
Full Text Available In this paper, the modeling of the mass transfer process in packed-bed reactors is presented and takes into account dispersion in the main fluid phase, internal diffusion of the reactant in the pores of the catalyst, and surface reaction inside the catalyst. The method of volume averaging is applied to obtain the governing equation for use on a small scale. The local mass equilibrium is assumed for obtaining the one-equation model for use on a large scale. The closure problems are developed subject to the length-scale constraints and the model of a spatially periodic porous medium. The expressions for effective diffusivity, hydrodynamic dispersion, total dispersion and the Darcy's law permeability tensors are presented. Solution of the set of final equations permits the variations of velocity and concentration of the chemical species along the packed-bed reactors to be obtained.
Song, Hyun Beom; Lee, Kang Ju; Seo, Il Ho; Lee, Ji Yong; Lee, Sang-Mok; Kim, Jin Hyoung; Kim, Jeong Hun; Ryu, WonHyoung
2015-07-10
It has been challenging for microneedles to deliver drugs effectively to thin tissues with little background support such as the cornea. Herein, we designed a microneedle pen system, a single microneedle with a spring-loaded microneedle applicator to provide impact insertion. To firmly attach solid microneedles with 140 μm in height at the end of macro-scale applicators, a transfer molding process was employed. The fabricated microneedle pens were then applied to mouse corneas. The microneedle pens successfully delivered rhodamine dye deep enough to reach the stromal layer of the cornea with small entry only about 1000 μm(2). When compared with syringes or 30 G needle tips, microneedle pens could achieve more localized and minimally invasive delivery without any chances of perforation. To investigate the efficacy of microneedle pens as a way of drug delivery, sunitinib malate proven to inhibit in vitro angiogenesis, was delivered to suture-induced angiogenesis model. When compared with delivery by a 30 G needle tip dipped with sunitinib malate, only delivery by microneedle pens could effectively inhibit corneal neovascularization in vivo. Microneedle pens could effectively deliver drugs to thin tissues without impairing merits of using microneedles: localized and minimally invasive delivery. Copyright © 2015 Elsevier B.V. All rights reserved.
Absolute Properties of the Pulsating Post-mass Transfer Eclipsing Binary OO Draconis
Lee, Jae Woo; Hong, Kyeongsoo; Koo, Jae-Rim; Park, Jang-Ho
2018-01-01
OO Dra is a short-period Algol system with a δ Sct-like pulsator. We obtained time-series spectra between 2016 February and May to derive the fundamental parameters of the binary star and to study its evolutionary scenario. The radial velocity (RV) curves for both components were presented, and the effective temperature of the hotter and more massive primary was determined to be {T}{eff,1}=8260+/- 210 K by comparing the disentangling spectrum and the Kurucz models. Our RV measurements were solved with the BV light curves of Zhang et al. using the Wilson-Devinney binary code. The absolute dimensions of each component are determined as follows: M 1 = 2.03 ± 0.06 {M}⊙ , M 2 = 0.19 ± 0.01 {M}⊙ , R 1 = 2.08 ± 0.03 {R}⊙ , R 2 = 1.20 ± 0.02 {R}⊙ , L 1 = 18 ± 2 {L}⊙ , and L 2 = 2.0 ± 0.2 {L}⊙ . Comparison with stellar evolution models indicated that the primary star resides inside the δ Sct instability strip on the main sequence, while the cool secondary component is noticeably overluminous and oversized. We demonstrated that OO Dra is an oscillating post-mass transfer R CMa-type binary; the originally more massive star became the low-mass secondary component through mass loss caused by stellar wind and mass transfer, and the gainer became the pulsating primary as the result of mass accretion. The R CMa stars, such as OO Dra, are thought to have formed by non-conservative binary evolution and ultimately to evolve into EL CVn stars.
Impact of Heat and Mass Transfer on MHD Oscillatory Flow of Jeffery ...
African Journals Online (AJOL)
The objective of this paper is to study Dufour, Soret and thermal conductivity on unsteady heat and mass transfer of magneto hydrodynamic (MHD) oscillatory flow of Jeffery fluid through a porous medium in a channel. The partial differential equations governing the flow have been solved numerically using semi-implicit ...
International Nuclear Information System (INIS)
Boccaccini, L.V.
1986-07-01
To take advantages of the semi-implicit computer models - to solve the two phase flow differential system - a proper averaging procedure is also needed for the source terms. In fact, in some cases, the correlations normally used for the source terms - not time averaged - fail using the theoretical time step that arises from the linear stability analysis used on the right handside. Such a time averaging procedure is developed with reference to the bubbly flow regime. Moreover, the concept of mass that must be exchanged to reach equilibrium from a non-equilibrium state is introduced to limit the mass transfer during a time step. Finally some practical calculations are performed to compare the different correlations for the average mass transfer rate developed in this work. (orig.) [de
Vas bhat, R.D.; Kuipers, J.A.M.; Versteeg, Geert
2000-01-01
An absorption model to study gas¿liquid mass transfer accompanied by reversible two-step reactions in the liquid phase has been presented. This model has been used to determine mass transfer rates, enhancement factors and concentration profiles over a wide range of process conditions. Although
Combined natural convection heat and mass transfer from vertical fin arrays
International Nuclear Information System (INIS)
Giri, A.; Narasimham, G.S.V.L.; Krishna Murthy, M.V.
2003-01-01
Natural convection transport processes play an important role in many applications like ice-storage air-conditioning. A mathematical formulation of natural convection heat and mass transfer over a shrouded vertical fin array is developed. The base plate is maintained at a temperature below the dew point of the surrounding moist air. Hence there occurs condensation of moisture on the base plate, while the fins may be partially or fully wet. A numerical study is performed by varying the parameters of the problem. The local and average Nusselt numbers decrease in streamwise direction and tend to approach fully developed values for sufficiently large values of the fin length. The results show that beyond a certain streamwise distance, further fin length does not improve the sensible and latent heat transfer performance, and that if dry fin analysis is used under moisture condensation conditions, the overall heat transfer will be underestimated by about 50% even at low buoyancy ratios
Higgs boson masses in a non-minimal supersymmetric model
International Nuclear Information System (INIS)
Tiesi, Alessandro
2002-01-01
A study of the neutral Higgs spectrum in a general Z 3 -breaking Next to Minimal Supersymmetric Standard Model (NMSSM) is reported in several significant contexts. Particular attention has been devoted to the upper bound on lightest Higgs boson. In the CP-conserving case we show that the extra terms involved in the general Z 3 -breaking superpotential do not affect the upper bound which remains unchanged: it is ∼ 136 GeV when tan β = 2.7. The Spontaneous CP Violation scenario in the Z 3 -breaking NMSSM can occur at tree-level. When the phases of the fields are small the spectrum shows the lightest Higgs particle to be an almost singlet CP-odd. The second lightest particle, a doublet almost-CP-even state, still manifests the upper bound of the CP-conserving case. When the CP-violating phases are large the lightest particle is a doublet with no definite CP parity and its mass shows the usual upper bound at ∼ 136 GeV. The large number of parameters involved in the effective potential can be significantly reduced in the Infrared Quasi Fixed Point (IRQFP) resulting after solving the Renormalization Group (RG) equations assuming universality for the soft SUSY breaking masses. In the Z 3 -breaking NMSSM, unlike the Z 3 -conserving NMSSM, it is possible to find a Higgs spectrum which is still compatible with both experiment and universality at the unification scale. Because in the IRQFP regime tan β ∼ 1.8 and the stop mixing parameter is reduced then the upper bound on the lightest Higgs boson turns out to be ∼ 121 GeV. This result is compatible with experimental data coming from LEPII and might be one of the next predictions to be tested at hadron collider experiments. (author)
Transfer of momentum, mass and charge in heavy ion collisions
International Nuclear Information System (INIS)
Beck, F.; Feldmeier, H.; Dworzecka, M.
1979-01-01
A model for the first two phases of heavy ion collisions based on the transport of single nucleons through the window between the two scattering nuclei is described in some detail. It is pointed out that the model can account simultaneously for a large portion of the energy transfer from relative to intrinsic motion and for the observed variances in mass and charge numbers for reaction times up to the order of 10 -21 s. (P.L.)
Constructal entransy dissipation minimization for 'volume-point' heat conduction
International Nuclear Information System (INIS)
Chen Lingen; Wei Shuhuan; Sun Fengrui
2008-01-01
The 'volume to point' heat conduction problem, which can be described as to how to determine the optimal distribution of high conductivity material through the given volume such that the heat generated at every point is transferred most effectively to its boundary, has became the focus of attention in the current constructal theory literature. In general, the minimization of the maximum temperature difference in the volume is taken as the optimization objective. A new physical quantity, entransy, has been identified as a basis for optimizing heat transfer processes in terms of the analogy between heat and electrical conduction recently. Heat transfer analyses show that the entransy of an object describes its heat transfer ability, just as the electrical energy in a capacitor describes its charge transfer ability. Entransy dissipation occurs during heat transfer processes, as a measure of the heat transfer irreversibility with the dissipation related thermal resistance. By taking equivalent thermal resistance (it corresponds to the mean temperature difference), which reflects the average heat conduction effect and is defined based on entransy dissipation, as an optimization objective, the 'volume to point' constructal problem is re-analysed and re-optimized in this paper. The constructal shape of the control volume with the best average heat conduction effect is deduced. For the elemental area and the first order construct assembly, when the thermal current density in the high conductive link is linear with the length, the optimized shapes of assembly based on the minimization of entransy dissipation are the same as those based on minimization of the maximum temperature difference, and the mean temperature difference is 2/3 of the maximum temperature difference. For the second and higher order construct assemblies, the thermal current densities in the high conductive link are not linear with the length, and the optimized shapes of the assembly based on the
Directory of Open Access Journals (Sweden)
E. R. Gouveia
2000-12-01
Full Text Available In the present work rheological characteristics and volumetric oxygen transfer coefficient (kLa were investigated during batch cultivations of Streptomyces clavuligerus NRRL 3585 for production of clavulanic acid. The experimental rheological data could be adequately described in terms of the power law model and logistic equation. Significant changes in the rheological parameters consistency index (K and flow behavior index (n were observed with the fermentation evolution. Interesting correlations between the consistency index (K/biomass concentration (C X and the flow behavior index (n/biomass concentration were proposed. Volumetric oxygen mass transfer coefficient (kLa was determined by the gas balance method. Classical correlation relating the volumetric oxygen mass transfer coefficient to the operating conditions, physical and to transport properties, including apparent viscosity (muap, could be applied to the experimental results.
International Nuclear Information System (INIS)
Kornienko, Y.
2000-01-01
The purpose has been to describe an approach suggested for constructing generalized closure relationships for local and subchannel wall friction, heat and mass transfer coefficients, with not only axial and transversal parameters taken into account, but azimuthal substance transfer effects as well. These constitutive relations that are primary for description of one- and two-phase one-dimensional flow models can be derived from the initial 3-D drift flux formulation. The approach is based on the Reynolds flux, boundary layer and generalized coefficient of substance transfer. One more task has been to illustrate the validity of the 'conformity principle' for the limiting cases. The method proposed is based on the similarity theory, boundary layer model, and a phenomenological description of the regularities of the substance transfer (momentum, heat, and mass), as well as on an adequate simulation of the forms of flow structure by a generalized approach to build (an integrated in form and semi-empirical in maintenance structure) analytical relationships for wall friction, heat and mass transfer coefficients. (author)
International Nuclear Information System (INIS)
Winzer, A.
1978-01-01
It is shown that a direct proportionality exists between the activation energy for the mass transfer at the respective crystal faces of ionic crystals and the frequency of the phonones (longitudinal-optical), Planck's constant being found once more as a proportionality constant. Thus it could be demonstrated that the different activation energies measured at different time intervals for the mass transfer processes at phase boundaries of ionic crystals can be attributed to the specific growth of the crystal faces. Thus, NaCl crystal fractions which were mechanically stressed (pulverized and sifted) and consequently contained a great amount of [111]- and [110]-faces, respectively, experimentally yielded an activation energy which agrees with the values determined by quantum theory when the frequency of propagation of the phonons is inserted into a derived equation. This relation was also confirmed by NaCl crystal fractions predominantly containing cubic faces. This also indicates that in mass transfer processes on phase boundaries of ionic crystals quantum mechanical laws are of importance. (author)
International Nuclear Information System (INIS)
Roy, Amitava
2010-01-01
Mass transfer is a vital unit operation in the processing of spent nuclear fuel in the backend of closed fuel cycle and Pulsed perforated plate extraction columns are used as mass transfer device for more than five decades. The pulsed perforated plate column is an agitated differential contactor, which has wide applicability due to its simplicity, high mass transfer efficiency, high through put, suitability for maintenance free remote operation, ease of cleaning/decontamination and cost effectiveness. Design of pulsed columns are based on a model proposed to describe the hydrodynamics and mass transfer. In equilibrium stage model, the HETS values are obtained from pilot plant experiments and then scaled empirically to design columns for industrial application. The dispersion model accounts for mass transfer kinetics and back-mixing. The drop population balance model can describe complex hydrodynamics of dispersed phase, that is, drop formation, break-up and drop-to-drop interactions. In recent years, significant progress has been made to model pulsed columns using CFD, which provides complete mathematical description of hydrodynamics in terms of spatial distribution of flow fields and 3D visualization. Under the condition of pulsation, the poly-dispersed nature of turbulent droplet swarm renders modeling difficult. In the absence of industry acceptance of proposed models, the conventional chemical engineering practice is to use HETS-NTS concept or HTU-NTU approach to design extraction columns. The practicability of HTU-NTU approach has some limitations due to the lack of experimental data on individual film mass transfer coefficients. Presently, the HETS-NTS concept has been used for designing the columns, which has given satisfactory performance. The design objective is mainly to arrive at the diameter and height of the mass transfer section for a specific plate geometry, fluid properties and pulsing condition to meet the intended throughput (capacity) and mass
Thandlam, Anil Kumar; Das, Chiranjib; Majumder, Subrata Kumar
2017-04-01
Investigation of wall-liquid mass transfer and heat transfer phenomena with gas-Newtonian and non-Newtonian fluids in vertically helical coil reactor have been reported in this article. Experiments were conducted to investigate the effect of various dynamic and geometric parameters on mass and heat transfer coefficients in the helical coil reactor. The flow pattern-based heat and mass transfer phenomena in the helical coil reactor are highlighted at different operating conditions. The study covered a wide range of geometric parameters such as diameter of the tube ( d t ), diameter of the coil ( D c ), diameter of the particle ( d p ), pitch difference ( p/D c ) and concentrations of non-Newtonian liquid. The correlation models for the heat and mass transfer coefficient based on the flow pattern are developed which may be useful in process scale-up of the helical coil reactor for industrial application. The frictional drag coefficient was also estimated and analyzed by mass transfer phenomena based on the electrochemical method.
Kinetics and mass-transfer phenomena in anaerobic granular sludge.
Gonzalez-Gil, G; Seghezzo, L; Lettinga, G; Kleerebezem, R
2001-04-20
The kinetic properties of acetate-degrading methanogenic granular sludge of different mean diameters were assessed at different up-flow velocities (V(up)). Using this approach, the influence of internal and external mass transfer could be estimated. First, the apparent Monod constant (K(S)) for each data set was calculated by means of a curve-fitting procedure. The experimental results revealed that variations in the V(up) did not affect the apparent K(S)-value, indicating that external mass-transport resistance normally can be neglected. With regard to the granule size, a clear increase in K(S) was found at increasing granule diameters. The experimental data were further used to validate a dynamic mathematical biofilm model. The biofilm model was able to describe reaction-diffusion kinetics in anaerobic granules, using a single value for the effective diffusion coefficient in the granules. This suggests that biogas formation did not influence the diffusion-rates in the granular biomass. Copyright 2001 John Wiley & Sons, Inc.
Mass transfer of Disperse Red 153 and its crude dye in supercritical CO2 fluid
Directory of Open Access Journals (Sweden)
Zheng Huan-Da
2017-01-01
Full Text Available In this paper, polyester fibers were dyed with Disperse Red 153 and its crude dye in supercritical CO2. The effect of dyeing temperature, dyeing time, dyeing pressure, as well as auxiliaries in the commercialized Disperse Red 153 on the dyeing performance of polyester fibers was investigated. The obtained results showed that the dyeing effect of crude dye for polyester was better than that of Disperse Red 153 in the same dyeing condition. The color strength values of the dyed polyester samples were increased gradually with the increase of temperature and pressure since mass transfer of dye was improved. In addition, the mass transfer model of Disperse Red 153 in supercritical CO2 was also proposed.
The results of the measurements of mass- and heat-transfer in the wet cooling tower
International Nuclear Information System (INIS)
Fabjan, Lj.; Gaspersic, B.
1979-01-01
These are the results of our investigations carried out on a packing inside a wet cooling tower for the purpose of studying the mass and heat transfer at the counterflow of water and humid air. The measurements on the experimental tower of the corresponding mathematical model reflect the average coefficient of mass and heat transfer for the unity of the active volume. Further the measurements of pressure drop at the air flow were carried out and thus the coefficient of aerodynamic losses were obtained. The results of measurements are given in the corresponding equations with the dimensionless numbers and diagrams. They will be of great use for the planning of new cooling towers. (author)
User's manual for the FEHM application - A finite-element heat- and mass-transfer code
International Nuclear Information System (INIS)
Zyvoloski, G.A.; Robinson, B.A.; Dash, Z.V.; Trease, L.L.
1997-07-01
The use of this code is applicable to natural-state studies of geothermal systems and groundwater flow. A primary use of the FEHM application will be to assist in the understanding of flow fields and mass transport in the saturated and unsaturated zones below the proposed Yucca Mountain nuclear waste repository in Nevada. The equations of heat and mass transfer for multiphase flow in porous and permeable media are solved in the FEHM application by using the finite-element method. The permeability and porosity of the medium are allowed to depend on pressure and temperature. The code also has provisions for movable air and water phases and noncoupled tracers; that is, tracer solutions that do not affect the heat- and mass-transfer solutions. The tracers can be passive or reactive. The code can simulate two-dimensional, two-dimensional radial, or three-dimensional geometries. In fact, FEHM is capable of describing flow that is dominated in many areas by fracture and fault flow, including the inherently three-dimensional flow that results from permeation to and from faults and fractures. The code can handle coupled heat and mass-transfer effects, such as boiling, dryout, and condensation that can occur in the near-field region surrounding the potential repository and the natural convection that occurs through Yucca Mountain due to seasonal temperature changes. This report outlines the uses and capabilities of the FEHM application, initialization of code variables, restart procedures, and error processing. The report describes all the data files, the input data, including individual input records or parameters, and the various output files. The system interface is described, including the software environment and installation instructions
DEFF Research Database (Denmark)
Hansen, Ernst; Mollerup, Jørgen
1999-01-01
The paper describes a method of simultaneous determination of the external and the solid phase mass-transfer coefficients from frontal analysis data. The protein flux to the solid particles is determined from the slope of the breakthrough curve and the mass-transfer coefficients are determined...
Energy Technology Data Exchange (ETDEWEB)
Guo, Yuming; Liu, Lijuan; Liang, Li [Shanxi Agricultural Univ. (China). Coll. of Engineering and Technology], E-mail: guoyuming99@sina.com
2008-07-01
Studying the effects mechanism of material physical parameters on the heat and mass transfer characteristics, the process parameters and energy consumption during freeze-drying process is of importance in improving the vacuum freeze-drying process with low energy consumption. In this paper, the sliced and mashed carrots of one variety were selected to perform the vacuum freeze-drying experiments. First, the variation laws of surface temperatures and sublimation front temperatures of the two shapes samples during the freeze-drying processes were analyzed, and it was verified that the process of sliced carrots is controlled by mass transfer, while that of the mashed ones is heat-transfer control. Second, the variations of water loss rate, energy consumption and temperature of the two shapes samples under the appropriate heating plate temperature and the different drying chamber pressure were analyzed. In addition, the effects of thermal conductivity and thermal diffusivity on freeze-drying time and process parameters were discussed by utilizing the theory of heat and mass transfer. In conclusion, under the heat transfer condition, the temperature of the heating plate should be as high as possible within the permitted range, and the drying chamber pressure should be set at optimal level. While under the mass transport-limited condition, the pressure level need to be altered in short time. (author)
Flow and Mass Transfer Performance in Short Pin-Fin Channels with Different Fin Shapes
Goldstein, R. J.; Chen, S. B.
1998-01-01
The mass transfer (analogous to heat transfer) and pressure loss characteristics of staggered short pin-fin arrays are investigated experimentally in the range of Reynolds number 3000 to 18,000 based on fin diameter and mean approach-flow velocity. Three different shapes of fins with aspect ratio of 2 are examined: one uniform-diameter circular fin (UDCF) and two stepped-diameter circular fins (SDCF1 and SDCF2). Flow visualization using oil-lampblack reveals complex flow characteristics assoc...
Gritti, Fabrice; Horvath, Krisztian; Guiochon, Georges
2012-11-09
The mass transfer kinetics of a few compounds (uracil, 112 Da), insulin (5.5 kDa), lysozyme (13.4 kDa), and bovine serum albumin (BSA, 67 kDa) in columns packed with several types of spherical particles was investigated under non-retained conditions, in order to eliminate the poorly known contribution of surface diffusion to overall sample diffusivity across the porous particles in RPLC. Diffusivity across particles is then minimum. Based on the porosity of the particles accessible to analytes, it was accurately estimated from the elution times, the internal obstruction factor (using Pismen correlation), and the hindrance diffusion factor (using Renkin correlation). The columns used were packed with fully porous particles 2.5 μm Luna-C(18) 100 Å, core-shell particles 2.6 μm Kinetex-C(18) 100 Å, 3.6 μm Aeris Widepore-C(18) 200 Å, and prototype 2.7 μm core-shell particles (made of two concentric porous shells with 100 and 300 Å average pore size, respectively), and with 3.3 μm non-porous silica particles. The results demonstrate that the porous particle structure and the solid-liquid mass transfer resistance have practically no effect on the column efficiency for small molecules. For them, the column performance depends principally on eddy dispersion (packing homogeneity), to a lesser degree on longitudinal diffusion (effective sample diffusivity along the packed bed), and only slightly on the solid-liquid mass transfer resistance (sample diffusivity across the particle). In contrast, for proteins, this third HETP contribution, hence the porous particle structure, together with eddy dispersion govern the kinetic performance of columns. Mass transfer kinetics of proteins was observed to be fastest for columns packed with core-shell particles having either a large core-to-particle ratio or having a second, external, shell made of a thin porous layer with large mesopores (200-300 Å) and a high porosity (~/=0.5-0.7). The structure of this external shell seems
Directory of Open Access Journals (Sweden)
German E. Cortes Garcia
2018-02-01
Full Text Available The Danckwerts’ plot method is a commonly used graphical technique to independently determine the interfacial area and mass-transfer coefficient in gas–liquid contactors. The method was derived in 1963 when computational capabilities were limited and intensified process equipment did not exist. A numerical analysis of the underlying assumptions of the method in this paper has shown a bias in the technique, especially for situations where mass-transfer rates are intensified, or where there is limited liquid holdup in the bulk compared to the film layers. In fact, systematic errors of up to 50% in the interfacial area, and as high as 90% in the mass-transfer coefficients, can be expected for modern, intensified gas–liquid contactors, even within the commonly accepted validity limits of a pseudo-first-order reaction and Hatta numbers in the range of 0.3 < Ha < 3. Given the current computational capabilities and the intensified mass-transfer rates in modern gas–liquid contactors, it is therefore imperative that the equations for reaction and diffusion in the liquid films are numerically solved and subsequently used to fit the interfacial area and mass-transfer coefficient to experimental data, which would traditionally be used in the graphical Danckwerts’ method.
Heat or mass transfer at low Péclet number for Brinkman and Darcy flow round a sphere
Bell, Christopher G.
2014-01-01
Prior research into the effect of convection on steady-state mass transfer from a spherical particle embedded in a porous medium has used the Darcy model to describe the flow. However, a limitation of the Darcy model is that it does not account for viscous effects near boundaries. Brinkman modified the Darcy model to include these effects by introducing an extra viscous term. Here we investigate the impact of this extra viscous term on the steady-state mass transfer from a sphere at low Péclet number, Pe 1. We use singular perturbation techniques to find the approximate asymptotic solution for the concentration profile. Mass-release from the surface of the sphere is described by a Robin boundary condition, which represents a first-order chemical reaction. We find that a larger Brinkman viscous boundary layer renders mass transport by convection less effective, and reduces the asymmetry in the peri-sphere concentration profiles. We provide simple analytical expressions that can be used to calculate the concentration profiles, as well as the local and average Sherwood numbers; and comparison to numerical simulations verifies the order of magnitude of the error in the asymptotic expansions. In the appropriate limits, the asymptotic results agree with solutions previously obtained for Stokes and Darcy flow. The solution for Darcy flow with a Robin boundary condition has not been considered previously in the literature and is a new result. Whilst the article has been formulated in terms of mass transfer, the analysis is also applicable to heat transfer, with concentration replaced by temperature and the Sherwood number by the Nusselt number. © 2013 Elsevier Ltd. All rights reserved.
International Nuclear Information System (INIS)
Dash, Z.V.; Robinson, B.A.; Zyvoloski, G.A.
1997-07-01
The requirements, design, and verification and validation of the software used in the FEHM application, a finite-element heat- and mass-transfer computer code that can simulate nonisothermal multiphase multicomponent flow in porous media, are described. The test of the DOE Code Comparison Project, Problem Five, Case A, which verifies that FEHM has correctly implemented heat and mass transfer and phase partitioning, is also covered
Energy Technology Data Exchange (ETDEWEB)
Dinh, T.N.; Bui, V.A.; Nourgaliev, R.R. [Royal Institute of Technology, Stockholm (Sweden)] [and others
1995-09-01
The objective of the paper is to study heat and mass transfer processes related to core melt discharge from a reactor vessel is a severe light water reactor accident. The phenomenology of the issue includes (1) melt convection in and heat transfer from the melt pool in contact with the vessel lower head wall; (2) fluid dynamics and heat transfer of the melt flow in the growing discharge hole; and (3) multi-dimensional heat conduction in the ablating lower head wall. A program of model development, validation and application is underway (i) to analyse the dominant physical mechanisms determining characteristics of the lower head ablation process; (ii) to develop and validate efficient analytic/computational methods for estimating heat and mass transfer under phase-change conditions in irregular moving-boundary domains; and (iii) to investigate numerically the melt discharge phenomena in a reactor-scale situation, and, in particular, the sensitivity of the melt discharge transient to structural differences and various in-vessel melt progression scenarios. The paper presents recent results of the analysis and model development work supporting the simulant melt-structure interaction experiments.
Heat Transfer and Mass Diffusion in Nanofluids over a Moving Permeable Convective Surface
Directory of Open Access Journals (Sweden)
Muhammad Qasim
2013-01-01
Full Text Available Heat transfer and mass diffusion in nanofluid over a permeable moving surface are investigated. The surface exhibits convective boundary conditions and constant mass diffusion. Effects of Brownian motion and thermophoresis are considered. The resulting partial differential equations are reduced into coupled nonlinear ordinary differential equations using suitable transformations. Shooting technique is implemented for the numerical solution. Velocity, temperature, and concentration profiles are analyzed for different key parameters entering into the problem. Performed comparative study shows an excellent agreement with the previous analysis.
Mass and heat transfer mechanism in wood during radio frequency/vacuum drying and numerical analysis
Institute of Scientific and Technical Information of China (English)
Xiaoran Jia; Jingyao Zhao; Yingchun Cai
2017-01-01
The mass and heat transfer mechanisms during radio frequency/vacuum (RF/V) drying of square-edged timber were analyzed and discussed in detail,and a new one-dimensional mathematical model to describe the transport phenomena of mass and heat during continuous RF/V drying was derived from conservation equations based on the mass and heat transfer theory of porous materials.The new model provided a relatively fast and efficient way to simulate vacuum drying behavior assisted by dielectric heating.Its advantages compared with the conventional models include:(1) Each independent variable has a separate control equation and is solved independently by converting the partial differential equation into a difference equation with the finite volume method;(2) The calculated data from different parts of the specimen can be displayed in the evolution curves,and the change law of the parameters can be better described.After analyzing the calculated results,most of the important phenomena observed during RF/V drying were adequately described by this model.
Hussain, Amir; Kangwa, Martin; Yumnam, Nivedita; Fernandez-Lahore, Marcelo
2015-12-01
The influence of internal mass transfer on productivity as well as the performance of packed bed bioreactor was determined by varying a number of parameters; chitosan coating, flow rate, glucose concentration and particle size. Saccharomyces cerevisiae cells were immobilized in chitosan and non-chitosan coated alginate beads to demonstrate the effect on particle side mass transfer on substrate consumption time, lag phase and ethanol production. The results indicate that chitosan coating, beads size, glucose concentration and flow rate have a significant effect on lag phase duration. The duration of lag phase for different size of beads (0.8, 2 and 4 mm) decreases by increasing flow rate and by decreasing the size of beads. Moreover, longer lag phase were found at higher glucose medium concentration and also with chitosan coated beads. It was observed that by increasing flow rates; lag phase and glucose consumption time decreased. The reason is due to the reduction of external (fluid side) mass transfer as a result of increase in flow rate as glucose is easily transported to the surface of the beads. Varying the size of beads is an additional factor: as it reduces the internal (particle side) mass transfer by reducing the size of beads. The reason behind this is the distance for reactants to reach active site of catalyst (cells) and the thickness of fluid created layer around alginate beads is reduced. The optimum combination of parameters consisting of smaller beads size (0.8 mm), higher flow rate of 90 ml/min and glucose concentration of 10 g/l were found to be the maximum condition for ethanol production.
Bounds on the Higgs mass in the standard model and the minimal supersymmetric standard model
Quiros, M.
1995-01-01
Depending on the Higgs-boson and top-quark masses, M_H and M_t, the effective potential of the {\\bf Standard Model} can develop a non-standard minimum for values of the field much larger than the weak scale. In those cases the standard minimum becomes metastable and the possibility of decay to the non-standard one arises. Comparison of the decay rate to the non-standard minimum at finite (and zero) temperature with the corresponding expansion rate of the Universe allows to identify the region, in the (M_H, M_t) plane, where the Higgs field is sitting at the standard electroweak minimum. In the {\\bf Minimal Supersymmetric Standard Model}, approximate analytical expressions for the Higgs mass spectrum and couplings are worked out, providing an excellent approximation to the numerical results which include all next-to-leading-log corrections. An appropriate treatment of squark decoupling allows to consider large values of the stop and/or sbottom mixing parameters and thus fix a reliable upper bound on the mass o...
Gas-liquid mass transfer and flow phenomena in the Peirce-Smith converter: a water model study
Zhao, Xing; Zhao, Hong-liang; Zhang, Li-feng; Yang, Li-qiang
2018-01-01
A water model with a geometric similarity ratio of 1:5 was developed to investigate the gas-liquid mass transfer and flow characteristics in a Peirce-Smith converter. A gas mixture of CO2 and Ar was injected into a NaOH solution bath. The flow field, volumetric mass transfer coefficient per unit volume ( Ak/V; where A is the contact area between phases, V is the volume, and k is the mass transfer coefficient), and gas utilization ratio ( η) were then measured at different gas flow rates and blow angles. The results showed that the flow field could be divided into five regions, i.e., injection, strong loop, weak loop, splashing, and dead zone. Whereas the Ak/V of the bath increased and then decreased with increasing gas flow rate, and η steadily increased. When the converter was rotated clockwise, both Ak/V and η increased. However, the flow condition deteriorated when the gas flow rate and blow angle were drastically increased. Therefore, these parameters must be controlled to optimal conditions. In the proposed model, the optimal gas flow rate and blow angle were 7.5 m3·h-1 and 10°, respectively.
Yao, Ye
2016-07-01
The physical mechanisms of heat and mass transfer enhancement by ultrasound have been identified by people. Basically, the effect of 'cavitation' induced by ultrasound is the main reason for the enhancement of heat and mass transfer in a liquid environment, and the acoustic streaming and vibration are the main reasons for that in a gaseous environment. The adsorbent regeneration and food drying/dehydration are typical heat and mass transfer process, and the intensification of the two processes by ultrasound is of complete feasibility. This paper makes an overview on recent studies regarding applications of power ultrasound to adsorbent regeneration and food drying/dehydration. The concerned adsorbents include desiccant materials (typically like silica gel) for air dehumidification and other ones (typically active carbon and polymeric resin) for water treatment. The applications of ultrasound in the regeneration of these adsorbents have been proved to be energy saving. The concerned foods are mostly fruits and vegetables. Although the ultrasonic treatment may cause food degradation or nutrient loss, it can greatly reduce the food processing time and decrease drying temperature. From the literature, it can be seen that the ultrasonic conditions (i.e., acoustic frequency and power levels) are always focused on during the study of ultrasonic applications. The increasing number of relevant studies argues that ultrasound is a very promising technology applied to the adsorbent regeneration and food drying/dehydration. Copyright © 2016 Elsevier B.V. All rights reserved.
Fluid Dynamics And Mass Transfer In Two-Fluid Taylor-Couette Flow
International Nuclear Information System (INIS)
Baier, G.; Graham, M.D.
1998-01-01
The Taylor-Couette instability of a single liquid phase can be used to enhance mass transfer processes such as filtration and membrane separations. We consider here the possibility of using this instability to enhance interphase transport in a two-fluid systems, with a view toward improved liquid-liquid extractions for biotechnology applications. We investigate the centrifugal instability of a pair of radially stratified immiscible liquids in the annular gap between concentric, corotating cylinders: two-fluid Taylor-Couette flow. Experiments show that a two-layer flow with a well-defined interface and Taylor vortices in each phase can be obtained. The experimental results are in good agreement with predictions of inviscid arguments based on a two-phase extension of Rayleigh's criterion, as well as with detailed linear stability calculations. For a given geometry, the most stable configuration occurs for fluids of roughly (exactly in the inviscid limit) equal dynamic viscosities. A number of preliminary mass transfer experiments have also been performed, in the presence of axial counterflow. The onset of Taylor vortices coincides with a clear decrease in the extent of axial dispersion and an increase in the rate of interphase transport, thus suggesting that this flow geometry may provide an effective means for countercurrent chromatographic separations
Experimental analysis and evaluation of the mass transfer process in a trickle-bed reactor
Directory of Open Access Journals (Sweden)
J.D. Silva
2003-10-01
Full Text Available A transient experimental analysis of a three-phase descendent-cocurrent trickle-bed H2O/CH4-Ar/g -Al2O3 system was made using the stimulus-response technique, with the gas phase as a reference. Methane was used as a tracer and injected into the argon feed and the concentration vs time profiles were obtained at the entrance and exit of the bed, which were maintained at 298K and 1.013 10(5 Pa. A mathematical model for the tracer was developed to estimate the axial dispersion overall gas-liquid mass transfer and liquid-solid mass transfer coefficients. Experimental and theoretical results were compared and shown to be in good agreement. The model was validated by two additional experiments, and the values of the coefficients obtained above were confirmed.
Mass transfer and power characteristics of stirred tank with Rushton and curved blade impeller
Directory of Open Access Journals (Sweden)
Thiyam Tamphasana Devi
2017-04-01
Full Text Available Present work compares the mass transfer coefficient (kLa and power draw capability of stirred tank employed with Rushton and curved blade impeller using computational fluid dynamics (CFD techniques in single and double impeller cases. Comparative analysis for different boundary conditions and mass transfer model has been done to assess their suitability. The predicted local kLa has been found higher in curved blade impeller than the Rushton impeller, whereas stirred tank with double impeller does not show variation due to low superficial gas velocity. The global kLa predicted has been found higher in curved blade impeller than the Rushton impeller in double and single cases. Curved blade impeller also exhibits higher power draw capability than the Rushton impeller. Overall, stirred tank with curved blade impeller gives higher efficiency in both single and double cases than the Rushton turbine
Mass transfer between gas and particles in a gas-solid trickle flow reactor
Kiel, J.H.A.; Kiel, J.H.A.; Prins, W.; van Swaaij, Willibrordus Petrus Maria
1992-01-01
Gas-solids mass transfer was studied for counter-current flow of gas and millimetre-sized solid particles over an inert packing at dilute phase or trickle flow conditions. Experimental data were obtained from the adsorption of water vapour on 640 and 2200 ¿m diameter molecular sieve spheres at
Mittermaier, M.; Ziegler, F.
2018-04-01
In this article we present a model describing a laminar film flow over a vertical isothermal plate whilst heat and mass transfer is occurring. We focus on a formulation where most common assumptions, such as constant property data and constant film thickness, have been cancelled. The hydrodynamic model results in longitudinal and transversal velocity components and their evolution in the entrance region. Heat and mass transfer occurs simultaneously and is modelled with respect to release of differential heat of solution as well as heat flow due to interdiffusion. The numerical solution is obtained by utilising a Newton-Raphson method to solve the finite difference formulation of the governing equations. Mass transfer across the film affects the development of both longitudinal and transversal velocity components. The hydrodynamics are modelled using a boundary layer approximation of the Navier-Stokes equations. The significance of simplifications on the hydrodynamic model are illustrated and discussed using a fully developed velocity profile (Nusselt flow) and a plug flow at the inlet for comparison. Even if a Nusselt profile is assumed, it develops further since mass is absorbed or desorbed. It is found that the onset of absorption occurs at shorter flow length when applying a plug flow at the inlet. If the film is initially in equilibrium, this results in a 9.3% increase in absorbed mass over a length of 0.03 m as compared with the Nusselt flow. A fluid with a viscosity five times the one of lithium bromide solution but sharing comparable properties apart from that, leads to lower overall heat and mass transfer rates. If the respective fluids are saturated at the inlet, the accumulated mass flux absorbed by lithium bromide solution is 2.2 times higher than the one absorbed by a high viscous fluid. However, when a plug flow is applied and the fluid is sub-cooled, ab initio the absorbed mass flux is slightly higher for a high viscous fluid. Assuming a sub
Energy Technology Data Exchange (ETDEWEB)
Busigin, A. [NITEK USA Inc., Ocala, FL (United States)
2015-03-15
Liquid Phase Catalytic Exchange (LPCE) is a key technology used in water detritiation systems. Rigorous simulation of LPCE is complicated when a column may have both hydrogen and deuterium present in significant concentrations in different sections of the column. This paper presents a general mass transfer model for a homogenous packed bed LPCE column as a set of differential equations describing composition change, and equilibrium equations to define the mass transfer driving force within the column. The model is used to show the effect of deuterium buildup in the bottom of an LPCE column from non-negligible D atom fraction in the bottom feed gas to the column. These types of calculations are important in the design of CECE (Combined Electrolysis and Catalytic Exchange) water detritiation systems.
Samala, Ravi K; Chan, Heang-Ping; Hadjiiski, Lubomir; Helvie, Mark A; Wei, Jun; Cha, Kenny
2016-12-01
Develop a computer-aided detection (CAD) system for masses in digital breast tomosynthesis (DBT) volume using a deep convolutional neural network (DCNN) with transfer learning from mammograms. A data set containing 2282 digitized film and digital mammograms and 324 DBT volumes were collected with IRB approval. The mass of interest on the images was marked by an experienced breast radiologist as reference standard. The data set was partitioned into a training set (2282 mammograms with 2461 masses and 230 DBT views with 228 masses) and an independent test set (94 DBT views with 89 masses). For DCNN training, the region of interest (ROI) containing the mass (true positive) was extracted from each image. False positive (FP) ROIs were identified at prescreening by their previously developed CAD systems. After data augmentation, a total of 45 072 mammographic ROIs and 37 450 DBT ROIs were obtained. Data normalization and reduction of non-uniformity in the ROIs across heterogeneous data was achieved using a background correction method applied to each ROI. A DCNN with four convolutional layers and three fully connected (FC) layers was first trained on the mammography data. Jittering and dropout techniques were used to reduce overfitting. After training with the mammographic ROIs, all weights in the first three convolutional layers were frozen, and only the last convolution layer and the FC layers were randomly initialized again and trained using the DBT training ROIs. The authors compared the performances of two CAD systems for mass detection in DBT: one used the DCNN-based approach and the other used their previously developed feature-based approach for FP reduction. The prescreening stage was identical in both systems, passing the same set of mass candidates to the FP reduction stage. For the feature-based CAD system, 3D clustering and active contour method was used for segmentation; morphological, gray level, and texture features were extracted and merged with a
Modulated mass-transfer model for superhumps in SU Ursae Majoris stars
Mineshige, Shin
1988-01-01
The response of a circular accretion disk to rapid modulation of the mass-transfer rate into the disk is explored in order to model superhumps in SU UMa stars. It is proposed that periodically enhanced flow may disrupt or heat up the outer disk and produce the dips noted just before the superhump peaks. The elliptical accretion-disk model with extended vertical disk structure can account for the observed characteristics of superhumps in these stars.
Modelling of convective heat and mass transfer in rotating flows
Shevchuk, Igor V
2016-01-01
This monograph presents results of the analytical and numerical modeling of convective heat and mass transfer in different rotating flows caused by (i) system rotation, (ii) swirl flows due to swirl generators, and (iii) surface curvature in turns and bends. Volume forces (i.e. centrifugal and Coriolis forces), which influence the flow pattern, emerge in all of these rotating flows. The main part of this work deals with rotating flows caused by system rotation, which includes several rotating-disk configurations and straight pipes rotating about a parallel axis. Swirl flows are studied in some of the configurations mentioned above. Curvilinear flows are investigated in different geometries of two-pass ribbed and smooth channels with 180° bends. The author demonstrates that the complex phenomena of fluid flow and convective heat transfer in rotating flows can be successfully simulated using not only the universal CFD methodology, but in certain cases by means of the integral methods, self-similar and analyt...
Aroudam, El. H.
In this paper, we present a modelling of the performance of a reactor of a solar cooling machine based carbon-ammonia activated bed. Hence, for a solar radiation, measured in the Energetic Laboratory of the Faculty of Sciences in Tetouan (northern Morocco), the proposed model computes the temperature distribution, the pressure and the ammonia concentration within the activated carbon bed. The Dubinin-Radushkevich formula is used to compute the ammonia concentration distribution and the daily cycled mass necessary to produce a cooling effect for an ideal machine. The reactor is heated at a maximum temperature during the day and cool at the night. A numerical simulation is carried out employing the recorded solar radiation data measured locally and the daily ambient temperature for the typical clear days. Initially the reactor is at ambient temperature, evaporating pressure; Pev=Pst(Tev=0 ∘C) and maintained at uniform concentration. It is heated successively until the threshold temperature corresponding to the condensing pressure; Pcond=Pst(Tam) (saturation pressure at ambient temperature; in the condenser) and until a maximum temperature at a constant pressure; Pcond. The cooling of the reactor is characterised by a fall of temperature to the minimal values at night corresponding to the end of a daily cycle. We use the mass balance equations as well as energy equation to describe heat and mass transfer inside the medium of three phases. A numerical solution of the obtained non linear equations system based on the implicit finite difference method allows to know all parameters characteristic of the thermodynamic cycle and consider principally the daily evolution of temperature, ammonia concentration for divers positions inside the reactor. The tube diameter of the reactor shows the dependence of the optimum value on meteorological parameters for 1 m2 of collector surface.
Demonstrating the Effect of Interphase Mass Transfer in a Transparent Fluidized Bed Reactor
Saayman, Jean; Nicol, Willie
2011-01-01
A demonstration experiment is described that employs the ozone decomposition reaction at ambient conditions on Fe2O3 impregnated Fluidized Catalytic Cracking (FCC) catalyst. Using a two-dimensional see-through column the importance of interphase mass transfer is clearly illustrated by the significant difference in ozone conversion between the…
Dietrich, Nicolas; Hebrard, Gilles
2018-02-01
An approach for visualizing and measuring the mass transfer around a single bubble rising in a quiescent liquid is reported. A colorimetric technique, developed by (Dietrich et al. Chem Eng Sci 100:172-182, 2013) using an oxygen sensitive redox dye was implemented. It was based on the reduction of the colorimetric indicator in presence of oxygen, this reduction being catalysed by sodium hydroxide and glucose. In this study, resazurin was selected because it offered various reduced forms with colours ranging from transparent (without oxygen) to pink (in presence of oxygen). These advantages made it possible to visualize the spatio-temporal oxygen mass transfer around rising bubbles. Images were recorded by a CCD camera and, after post-processing, the shape, size, and velocity of the bubbles were measured and the colours around the bubbles mapped. A calibration, linking the level of colour with the dissolved oxygen concentration, enabled colour maps to be converted into oxygen concentration fields. A rheoscopic fluid was used to visualize the wake of the bubbles. A calculation method was also developed to determine the transferred oxygen fluxes around bubbles of two sizes (d = 0.82 mm and d = 2.12 mm) and the associated liquid-side mass transfer coefficients. The results compared satisfactorily with classical global measurements made by oxygen micro-sensors or from the classical models. This study thus constitutes a striking example of how this new colorimetric method could become a remarkable tool for exploring gas-liquid mass transfer in fluids.
Monteiro, Cláudio Vinicius Barbosa; UEM; Righetto, Aderson Roberto; Universidade Estadual de Maringá; Souza, Leonardo César de; Universidade Estadual de Maringá; Paraíso, Paulo Roberto; UEM; Jorge, Luiz Mario de Matos; UEM
2010-01-01
The warming of a bottle of beer during a Friday evening happy hour directly involves transport phenomena, such as mass transfer due to condensation of air humidity on the bottle surface and heat transfer from the ambient to the bottle, which occurs by free convection and water condensation. Both processes happen simultaneously and are directly associated with the heat and mass transfer coefficients involved, which are affected by the ambient humidity and temperature. Several runs were made in...
Energy Technology Data Exchange (ETDEWEB)
Tobajas, M.; Garcia-Calvo, E. [Dept. de Ingenieria Quimica, Univ. de Alcala, Alcala de Henares (Spain)
2000-05-01
Mass transfer in bioreactors has been examined. In the present work, dynamic methods are used for the determination of K{sub L}a values for water, model media and a fermentation broth (Candida utilis) in an airlift reactor. The conventional dynamic method is applied at the end of the microbial process in order to avoid an alteration in the metabolism of the microorganisms. New dynamic methods are used to determine K{sub L}a in an airlift reactor during the microbial growth of Candida utilis on glucose. One of the methods is based on the continuous measurement of carbon dioxide production while the other method is based on the relationship between the oxygen transfer and biomass growth rates. These methods of determining K{sub L}a does not interfere with the microorganisms action. A theoretical mass transfer model has been used for K{sub L}a estimation for the systems described above. Some differences between calculated and measured values are found for fermentation processes due to the model is developed for two-phase air-water systems. Nevertheless, the average deviation between the predicted values and those obtained from the relationship between oxygen transfer and biomass production rates are lower than 25% in any case. (orig.)
Miano, Alberto Claudio; Ibarz, Albert; Augusto, Pedro Esteves Duarte
2016-03-01
The aim of this work was to demonstrate how ultrasound mechanisms (direct and indirect effects) improve the mass transfer phenomena in food processing, and which part of the process they are more effective in. Two model cases were evaluated: the hydration of sorghum grain (with two water activities) and the influx of a pigment into melon cylinders. Different treatments enabled us to evaluate and discriminate both direct (inertial flow and "sponge effect") and indirect effects (micro channel formation), alternating pre-treatments and treatments using an ultrasonic bath (20 kHz of frequency and 28 W/L of volumetric power) and a traditional water-bath. It was demonstrated that both the effects of ultrasound technology are more effective in food with higher water activity, the micro channels only forming in moist food. Moreover, micro channel formation could also be observed using agar gel cylinders, verifying the random formation of these due to cavitation. The direct effects were shown to be important in mass transfer enhancement not only in moist food, but also in dry food, this being improved by the micro channels formed and the porosity of the food. In conclusion, the improvement in mass transfer due to direct and indirect effects was firstly discriminated and described. It was proven that both phenomena are important for mass transfer in moist foods, while only the direct effects are important for dry foods. Based on these results, better processing using ultrasound technology can be obtained. Copyright © 2015 Elsevier B.V. All rights reserved.
DEFF Research Database (Denmark)
Mayer, Philipp; Karlson, U.; Christensen, P.S.
2005-01-01
Unstirred boundary layers (UBLs) often act as a bottleneck for the diffusive transport of hydrophobic organic compounds (HOCs) in the environment. Therefore, a microscale technique was developed for quantifying mass transfer through a 100-μm thin UBL, with the medium composition of the UBL...... as the controllable factor. The model compound fluoranthene had to (1) partition from a contaminated silicone disk (source) into the medium, (2) then diffuse through 100 μm of medium (UBL), and finally (3) partition into a clean silicone layer (sink). The diffusive mass transfer from source to sink was monitored over...... of magnitude. These results demonstrate that medium constituents, which normally are believed to bind hydrophobic organic chemicals, actually can enhance the diffusive mass transfer of HOCs in the vicinity of a diffusion source (e.g., contaminated soil particles). The technique can be used to evaluate...
Mass transfer measurements in foams
International Nuclear Information System (INIS)
Leblond, J.G.; Fournel, B.
2004-01-01
Full text of publication follows:This study participates to the elaboration of a method for decontamination of the inside surfaces of steel structures (pipes, tanks,...). The solution which has been chosen is to attack the surface of the structure by a dipping solution. In order to reduce the quantity of product to be recovered and treated at the end of the cleaning process, the active solution will be introduced as a foam. During its free or forced drainage the foam supplies an active liquid film along the structure surfaces. It was important to know if the transfers of the dipping liquid inside the foam and between foam and wall film are sufficient to allow a correct supplying of the active liquid at the wall and a correct dragging of the dipped products. The objective of this work is to develop a numerical model which simulates the various transfers. However such a modeling cannot be performed without a thorough knowledge of the different transfer parameters in the foam and in the film. The following study has been performed on a model foam (foaming water + air) held in a smooth vertical glass pipe and submitted to a forced drainage by the foaming water (water + surfactants). The liquid transfer involves the dispersion of the drainage liquid inside the foam and the transfer between the foam and the liquid film flowing down at the wall. The different transfers has been analyzed by NMR using a PFGSE-NMR sequence, which allows to determine the propagator, i.e., the probability density of the liquid particle displacements during a given time interval Δt, along a selected direction. This study allowed to measure, firstly, the mean liquid and the liquid dispersion in the foam along the vertical and horizontal direction, and secondly, the vertical mean velocity in the parietal liquid film. (authors)
DEFF Research Database (Denmark)
Mussati, Sergio F.; Gernaey, Krist; Morosuk, Tatiana
2016-01-01
exergy loss rate, the total heat transfer area, and the total annual cost of the system. It was found that the optimal solution obtained by minimization of the total exergy loss rate provides “theoretical” upper bounds not only for the total heat transfer area of the system but also for each process unit...... and all stream temperatures, while the optimal solution obtained by minimization of the total heat transfer area provides the lower bounds for these model variables, to solve a cost optimization problem. The minimization of the total exergy loss rate by varying parametrically the available total heat...... transfer area between these bounds was also performed, allowing to see how the optimal distribution of the available total heat transfer area among the system components, as well as the operating conditions (stream temperature, pressure, composition, and mass flow rate) and heat loads, vary qualitatively...
Mass transfer effect of the stalk contraction-relaxation cycle of Vorticella convallaria
Zhou, Jiazhong; Admiraal, David; Ryu, Sangjin
2014-11-01
Vorticella convallaria is a genus of protozoa living in freshwater. Its stalk contracts and coil pulling the cell body towards the substrate at a remarkable speed, and then relaxes to its extended state much more slowly than the contraction. However, the reason for Vorticella's stalk contraction is still unknown. It is presumed that water flow induced by the stalk contraction-relaxation cycle may augment mass transfer near the substrate. We investigated this hypothesis using an experimental model with particle tracking velocimetry and a computational fluid dynamics model. In both approaches, Vorticella was modeled as a solid sphere translating perpendicular to a solid surface in water. After having been validated by the experimental model and verified by grid convergence index test, the computational model simulated water flow during the cycle based on the measured time course of stalk length changes of Vorticella. Based on the simulated flow field, we calculated trajectories of particles near the model Vorticella, and then evaluated the mass transfer effect of Vorticella's stalk contraction based on the particles' motion. We acknowlege support from Laymann Seed Grant of the University of Nebraska-Lincoln.
International Nuclear Information System (INIS)
Cheng, C.-Y.
2006-01-01
This work examines the effects of the modified Darcy number, the buoyancy ratio and the inner radius-gap ratio on the fully developed natural convection heat and mass transfer in a vertical annular non-Darcy porous medium with asymmetric wall temperatures and concentrations. The exact solutions for the important characteristics of fluid flow, heat transfer, and mass transfer are derived by using a non-Darcy flow model. The modified Darcy number is related to the flow resistance of the porous matrix. For the free convection heat and mass transfer in an annular duct filled with porous media, increasing the modified Darcy number tends to increase the volume flow rate, total heat rate added to the fluid, and the total species rate added to the fluid. Moreover, an increase in the buoyancy ratio or in the inner radius-gap ratio leads to an increase in the volume flow rate, the total heat rate added to the fluid, and the total species rate added to the fluid
Netcher, Andrea C; Duranceau, Steven J
2016-03-01
In surface water treatment, ultrafiltration (UF) membranes are widely used because of their ability to supply safe drinking water. Although UF membranes produce high-quality water, their efficiency is limited by fouling. Improving UF filtrate productivity is economically desirable and has been attempted by incorporating sustainable biofiltration processes as pretreatment to UF with varying success. The availability of models that can be applied to describe the effectiveness of biofiltration on membrane mass transfer are lacking. In this work, UF water productivity was empirically modeled as a function of biofilter feed water quality using either a quadratic or Gaussian relationship. UF membrane mass transfer variability was found to be governed by the dimensionless mass ratio between the alkalinity (ALK) and dissolved organic carbon (DOC). UF membrane productivity was optimized when the biofilter feed water ALK to DOC ratio fell between 10 and 14. Copyright © 2015 Elsevier Ltd. All rights reserved.
DEFF Research Database (Denmark)
Zhang, Ge; He, Wenna; Fang, Lei
2013-01-01
The transfer mechanism of volatile organic compounds (VOCs) being trapped inside the various types of adsorbents is usually regarded as mere diffusion. This paper investigated the contribution of convective mass transfer inside the adsorbents used for VOC air-cleaning. The adsorbents are typically...
Gu, Kezhuan; Dogan, Neslihan; Coley, Kenneth S.
2018-06-01
The current paper seeks to demonstrate the general applicability of the authors' recently developed treatment of surface renewal during decarburization of Fe-C-S alloys and its effect on the mass transport of phosphorus in the metal phase. The proposed model employs a quantitative model of CO bubble nucleation in the metal to predict the rate of surface renewal, which can then in turn be used to predict the mass-transfer coefficient for phosphorus. A model of mixed transport control in the slag and metal phases was employed to investigate the dephosphorization kinetics between a liquid iron alloy and oxidizing slag. Based on previous studies of the mass-transfer coefficient of FeO in the slag, it was possible to separate the mass transfer coefficient of phosphorus in metal phase, km , from the overall mass-transfer coefficient k_{{o}} . Using this approach, km was investigated under a wide range of conditions and shown to be represented reasonably by the mechanism proposed. The mass-transfer model was tested against results from the literature over a wide range of conditions. The analysis showed that the FeO content in the slag, silicon in the metal and the experimental temperature have strong impact on, km , almost entirely because of their effect on decarburization behavior.
Solid foam packings for multiphase reactors: Modelling of liquid holdup and mass transfer
Stemmet, C.P.; Schaaf, van der J.; Kuster, B.F.M.; Schouten, J.C.
2006-01-01
In this paper, experimental and modeling results are presented of the liquid holdup and gas–liquid mass transfer characteristics of solid foam packings. Experiments were done in a semi-2D transparent bubble column with solid foam packings of aluminum in the range of 5–40 pores per inch (ppi). The
Directory of Open Access Journals (Sweden)
C.S.K. Raju
2016-03-01
Full Text Available In this study we analyzed the flow, heat and mass transfer behavior of Casson fluid past an exponentially permeable stretching surface in presence of thermal radiation, magneticfield, viscous dissipation, heat source and chemical reaction. We presented dual solutions by comparing the results of the Casson fluid with the Newtonian fluid. The governing partial nonlinear differential equations of the flow, heat and mass transfer are transformed into ordinary differential equations by using similarity transformation and solved numerically by using Matlab bvp4c package. The effects of various non-dimensional governing parameters on velocity, temperature and concentration profiles are discussed and presented graphically. Also, the friction factor, Nusselt and Sherwood numbers are analyzed and presented in tabular form for both Casson and Newtonian fluids separately. Under some special conditions the results of the present study have an excellent agreement with existing studies for both Casson and Newtonian fluid cases.
Mass transfer performance of blended alkanolamines for CO{sub 2} capture in packed absorbers
Energy Technology Data Exchange (ETDEWEB)
Setameteekul, A.; Veawab, A.; Aroonwilas, A.; Tontiwachwuthikul, P. [Regina Univ., SK (Canada)
2003-07-01
Acid gases are removed from industrial gas streams using the alkanolamine absorption process. There has been recent interest in extending the process to remove carbon dioxide from industrial waste gases. The process based on conventional alkanolamines is not economically viable because of the associated high energy costs. It was suggested that blended alkanolamines would significantly reduce energy consumption, thereby resulting in a reduction in process costs. The main disadvantage of using blended alkanolamines is a decrease in absorption performance. This study examines the mass transfer behaviour of carbon dioxide into blended alkanolamine solutions. It also compares their performance with the baseline performance of monoethanolamine (MEA). A series of absorption experiments were conducted in a bench-scale packed absorber. The blended alkanolamines included mixtures of MEA and methyldiethanolamine, as well as mixtures of diethanolamine and methyldiethanolamine. The results indicated the general mass transfer coefficient as a function of operating conditions.
Microscale Enhancement of Heat and Mass Transfer for Hydrogen Energy Storage
Energy Technology Data Exchange (ETDEWEB)
Drost, Kevin [Oregon State Univ., Corvallis, OR (United States); Jovanovic, Goran [Oregon State Univ., Corvallis, OR (United States); Paul, Brian [Oregon State Univ., Corvallis, OR (United States)
2015-09-30
The document summarized the technical progress associated with OSU’s involvement in the Hydrogen Storage Engineering Center of Excellence. OSU focused on the development of microscale enhancement technologies for improving heat and mass transfer in automotive hydrogen storage systems. OSU’s key contributions included the development of an extremely compact microchannel combustion system for discharging hydrogen storage systems and a thermal management system for adsorption based hydrogen storage using microchannel cooling (the Modular Adsorption Tank Insert or MATI).
Modulated mass-transfer model for superhumps in SU Ursae Majoris stars
International Nuclear Information System (INIS)
Mineshige, S.
1988-01-01
The response of a circular accretion disk to rapid modulation of the mass-transfer rate into the disk is explored in order to model superhumps in SU UMa stars. It is proposed that periodically enhanced flow may disrupt or heat up the outer disk and produce the dips noted just before the superhump peaks. The elliptical accretion-disk model with extended vertical disk structure can account for the observed characteristics of superhumps in these stars. 52 references
Zhang, Yaning; Xu, Fei; Li, Bingxi; Kim, Yong-Song; Zhao, Wenke; Xie, Gongnan; Fu, Zhongbin
2018-04-01
This study aims to validate the three-phase heat and mass transfer model developed in the first part (Three phase heat and mass transfer model for unsaturated soil freezing process: Part 1 - model development). Experimental results from studies and experiments were used for the validation. The results showed that the correlation coefficients for the simulated and experimental water contents at different soil depths were between 0.83 and 0.92. The correlation coefficients for the simulated and experimental liquid water contents at different soil temperatures were between 0.95 and 0.99. With these high accuracies, the developed model can be well used to predict the water contents at different soil depths and temperatures.
Energy Technology Data Exchange (ETDEWEB)
Worth Longest, P. [Virginia Commonwealth University, Richmond, VA (United States). Dept. of Mechanical Engineering; Kleinstreuer, C. [North Carolina State University, Raleigh, NC (United States). Dept. of Mechanical and Aerospace Engineering
2004-10-01
Individual and interacting effects of uniform flow, plane shear, and near-wall proximity on spherical droplet heat and mass transfer have been assessed for low Reynolds number conditions beyond the creeping flow regime. Validated resolved volume simulations were used to compute heat and mass transfer surface gradients of two-dimensional axisymmetric droplets and three-dimensional spherical droplets near planar wall boundaries for conditions consistent with inhalable aerosols (5 {<=} d {<=} 300 {mu}m) in the upper respiratory tract. Results indicate that planar shear significantly impacts droplet heat and mass transfer for shear-based Reynolds numbers greater than 1, which occur for near-wall respiratory aerosols with diameters in excess of 50 {mu}m. Wall proximity is shown to significantly enhance heat and mass transfer due to conduction and diffusion at separation distances less than five particle diameters and for small Reynolds numbers. For the Reynolds number conditions of interest, significant non-linear effects arise due to the concurrent interaction of uniform flow and shear such that linear superposition of Sherwood or Nusselt number terms is not allowable. Based on the validated numeric simulations, multivariable Sherwood and Nusselt number correlations are provided to account for individual flow characteristics and concurrent non-linear interactions of uniform flow, planar shear, and near-wall proximity. These heat and mass transfer correlations can be applied to effectively compute condensation and evaporation rates of potentially toxic or therapeutic aerosols in the upper respiratory tract, where non-uniform flow and wall proximity are expected to significantly affect droplet transport, deposition, and vapor formation. (author)
Heat Transfer and Entropy Generation Analysis of an Intermediate Heat Exchanger in ADS
Wang, Yongwei; Huai, Xiulan
2018-04-01
The intermediate heat exchanger for enhancement heat transfer is the important equipment in the usage of nuclear energy. In the present work, heat transfer and entropy generation of an intermediate heat exchanger (IHX) in the accelerator driven subcritical system (ADS) are investigated experimentally. The variation of entropy generation number with performance parameters of the IHX is analyzed, and effects of inlet conditions of the IHX on entropy generation number and heat transfer are discussed. Compared with the results at two working conditions of the constant mass flow rates of liquid lead-bismuth eutectic (LBE) and helium gas, the total pumping power all tends to reduce with the decreasing entropy generation number, but the variations of the effectiveness, number of transfer units and thermal capacity rate ratio are inconsistent, and need to analyze respectively. With the increasing inlet mass flow rate or LBE inlet temperature, the entropy generation number increases and the heat transfer is enhanced, while the opposite trend occurs with the increasing helium gas inlet temperature. The further study is necessary for obtaining the optimized operation parameters of the IHX to minimize entropy generation and enhance heat transfer.
Erosion and mass transfer of Mo, W and Nb under neutron irradiation of high temperature materials
International Nuclear Information System (INIS)
Berzhatyj, V.I.; Luk'yanov, A.N.; Zavalishin, A.A.; Tkach, V.N.; Fedorenko, A.I.
1980-01-01
Studies have been made of the medium composition in thermionic fuel elements of two types during reactor tests; erosion and mass transfer of electrode materials have been investigated in the after-reactor analysis of the tested fuel elements. The studies of electrode material evaporation at the conditions approaching (in environment temperature and composition) those of reactor tests of thermionic fuel elements have shown that the process proceeds in the form of metal oxides. Evaporation rates are determined, the mechanism of evaporation is discussed, and the analytical dependences are obtained for calculating the evaporation rates of Mo and W at certain temperature and gaseous medium composition. It is found that the main contribution to the material transfer off the Mo and Nb surfaces under a high-temperature reactor irradiation comes through the thermal evaporation; in the case of tungsten at the same experimental conditions the rates of mass transfer due to thermal evaporation and neutron sputtering are nearly the same [ru
Modeling of Heat and Mass Transfer in a TEC-Driven Lyophilizer
Yuan, Zeng-Guang; Hegde, Uday; Litwiller, Eric; Flynn, Michael; Fisher, John
2006-01-01
Dewatering of wet waste during space exploration missions is important for crew safety as it stabilizes the waste. It may also be used to recover water and serve as a preconditioning step for waste compaction. A thermoelectric cooler (TEC)-driven lyophilizer is under development at NASA Ames Research Center for this purpose. It has three major components: (i) an evaporator section where water vapor sublimes from the frozen waste, (ii) a condenser section where this water vapor deposits as ice, and (iii) a TEC section which serves as a heat pump to transfer heat from the condenser to the evaporator. This paper analyses the heat and mass transfer processes in the lyophilizer in an effort to understand the ice formation behavior in the condenser. The analysis is supported by experimental observations of ice formation patterns in two different condenser units.
International Nuclear Information System (INIS)
Shen, Yanwen; Brown, Robert; Wen, Zhiyou
2014-01-01
Highlights: • Syngas fermentation process is limited by gas-to-liquid mass transfer. • A novel monolithic biofilm reactor (MBR) for efficient mass transfer was developed. • MBR with slug flow resulted in higher k L a than bubble column reactor (BCR). • MBR enhanced ethanol productivity by 53% compared to BCR. • MBR was demonstrated as a promising reactor configuration for syngas fermentation. - Abstract: Syngas fermentation is a promising process for producing fuels and chemicals from lignocellulosic biomass. Currently syngas fermentation faces several engineering challenges, with gas-to-liquid mass transfer limitation representing the major bottleneck. The aim of this work is to evaluate the performance of a monolithic biofilm reactor (MBR) as a novel reactor configuration for syngas fermentation. The volumetric mass transfer coefficient (k L a) of the MBR was evaluated in abiotic conditions within a wide range of gas flow rates (i.e., gas velocity in monolithic channels) and liquid flow rates (i.e., liquid velocity in the channels). The k L a values of the MBR were higher than those of a controlled bubble column reactor (BCR) in certain conditions, due to the slug flow pattern in the monolithic channels. A continuous syngas fermentation using Clostridium carboxidivorans P7 was conducted in the MBR system under varying operational conditions, with the variables including syngas flow rate, liquid recirculation between the monolithic column and reservoir, and dilution rate. It was found that the syngas fermentation performance – measured by such parameters as syngas utilization efficiency, ethanol concentration and productivity, and ratio of ethanol to acetic acid – depended not only on the mass transfer efficiency but also on the biofouling or abrading of the biofilm attached on the monolithic channel wall. At a condition of 300 mL/min of syngas flow rate, 500 mL/min of liquid flow rate, and 0.48 day −1 of dilution rate, the MBR produced much higher
Pedretti, D.; Fernàndez-Garcia, D.; Sanchez-Vila, X.; Bolster, D.; Benson, D. A.
2014-02-01
Aquifer hydraulic properties such as hydraulic conductivity (K) are ubiquitously heterogeneous and typically only a statistical characterization can be sought. Additionally, statistical anisotropy at typical characterization scales is the rule. Thus, regardless of the processes governing solute transport at the local (pore) scale, transport becomes non-Fickian. Mass-transfer models provide an efficient tool that reproduces observed anomalous transport; in some cases though, these models lack predictability as model parameters cannot readily be connected to the physical properties of aquifers. In this study, we focus on a multirate mass-transfer model (MRMT), and in particular the apparent capacity coefficient (β), which is a strong indicator of the potential of immobile zones to capture moving solute. We aim to find if the choice of an apparent β can be phenomenologically related to measures of statistical anisotropy. We analyzed an ensemble of random simulations of three-dimensional log-transformed multi-Gaussian permeability fields with stationary anisotropic correlation under convergent flow conditions. It was found that apparent β also displays an anisotropic behavior, physically controlled by the aquifer directional connectivity, which in turn is controlled by the anisotropic correlation model. A high hydraulic connectivity results in large β values. These results provide new insights into the practical use of mass-transfer models for predictive purposes.
Local Transfer Coefficient, Smooth Channel
Directory of Open Access Journals (Sweden)
R. T. Kukreja
1998-01-01
Full Text Available Naphthalene sublimation technique and the heat/mass transfer analogy are used to determine the detailed local heat/mass transfer distributions on the leading and trailing walls of a twopass square channel with smooth walls that rotates about a perpendicular axis. Since the variation of density is small in the flow through the channel, buoyancy effect is negligible. Results show that, in both the stationary and rotating channel cases, very large spanwise variations of the mass transfer exist in he turn and in the region immediately downstream of the turn in the second straight pass. In the first straight pass, the rotation-induced Coriolis forces reduce the mass transfer on the leading wall and increase the mass transfer on the trailing wall. In the turn, rotation significantly increases the mass transfer on the leading wall, especially in the upstream half of the turn. Rotation also increases the mass transfer on the trailing wall, more in the downstream half of the turn than in the upstream half of the turn. Immediately downstream of the turn, rotation causes the mass transfer to be much higher on the trailing wall near the downstream corner of the tip of the inner wall than on the opposite leading wall. The mass transfer in the second pass is higher on the leading wall than on the trailing wall. A slower flow causes higher mass transfer enhancement in the turn on both the leading and trailing walls.
Numerical investigation of vapor–liquid heat and mass transfer in porous media
International Nuclear Information System (INIS)
Xin, Chengyun; Rao, Zhonghao; You, Xinyu; Song, Zhengchang; Han, Dongtai
2014-01-01
Highlights: • The heat and mass transfer behaviors in porous media was investigated. • A modified separate flow model (MSFM) was developed. • The influence of heat flux direction on heat and fluid flow behaviors is great. • The saturation profile is weakly discontinuous on the phase interface. • A countercurrent flow exists in two-phase region. - Abstract: A modified separate flow model (MSFM) is developed to numerically investigate the heat and mass transfer behaviors in porous media in this paper. In the MSFM, the effects of capillarity, liquid phase change, nonisothermal two-phase region and the local thermal non-equilibrium (LTNE) are considered. The vapor and liquid velocities are both converted into intermediate variables in the simulations and conveniently convergent solutions are obtained because a special upwind scheme for the convection or boiling heat transfer source and variable convergence factors are simultaneously employed. Two typical numerical examples with a one-dimension model of porous media are studied that the high heat fluxes are vertical and parallel to the fluid flow direction, respectively. And the results indicated that the influence of heat flux direction on heat and fluid flow behaviors in porous media is great. The nonisothermal phenomenon in the two-phase region is obvious for the former while the LTNE phenomenon is remarkable in the two-phase region for the latter. The results also showed several similar behaviors that the saturation profile is weakly discontinuous on the phase interface and a countercurrent flow exists in two-phase region
Kheirolomoom, Azadeh; Khorasheh, Farhad; Fazelinia, Hossein
2002-01-01
Immobilization of enzymes on nonporous supports provides a suitable model for investigating the effect of external mass transfer limitation on the reaction rate in the absence of internal diffusional resistance. In this study, deacylation of penicillin G was investigated using penicillin acylase immobilized on ultrafine silica particles. Kinetic studies were performed within the low-substrate-concentration region, where the external mass transfer limitation becomes significant. To predict the apparent kinetic parameters and the overall effectiveness factor, knowledge of the external mass transfer coefficient, k(L)a, is necessary. Although various correlations exist for estimation of k(L)a, in this study, an optimization scheme was utilized to obtain this coefficient. Using the optimum values of k(L)a, the initial reaction rates were predicted and found to be in good agreement with the experimental data.
User`s manual for the FEHM application -- A finite-element heat- and mass-transfer code
Energy Technology Data Exchange (ETDEWEB)
Zyvoloski, G.A.; Robinson, B.A.; Dash, Z.V.; Trease, L.L.
1997-07-01
The use of this code is applicable to natural-state studies of geothermal systems and groundwater flow. A primary use of the FEHM application will be to assist in the understanding of flow fields and mass transport in the saturated and unsaturated zones below the proposed Yucca Mountain nuclear waste repository in Nevada. The equations of heat and mass transfer for multiphase flow in porous and permeable media are solved in the FEHM application by using the finite-element method. The permeability and porosity of the medium are allowed to depend on pressure and temperature. The code also has provisions for movable air and water phases and noncoupled tracers; that is, tracer solutions that do not affect the heat- and mass-transfer solutions. The tracers can be passive or reactive. The code can simulate two-dimensional, two-dimensional radial, or three-dimensional geometries. In fact, FEHM is capable of describing flow that is dominated in many areas by fracture and fault flow, including the inherently three-dimensional flow that results from permeation to and from faults and fractures. The code can handle coupled heat and mass-transfer effects, such as boiling, dryout, and condensation that can occur in the near-field region surrounding the potential repository and the natural convection that occurs through Yucca Mountain due to seasonal temperature changes. This report outlines the uses and capabilities of the FEHM application, initialization of code variables, restart procedures, and error processing. The report describes all the data files, the input data, including individual input records or parameters, and the various output files. The system interface is described, including the software environment and installation instructions.
Jang, Nulee; Yasin, Muhammad; Park, Shinyoung; Lovitt, Robert W; Chang, In Seop
2017-09-01
A mathematical model of microbial kinetics was introduced to predict the overall volumetric gas-liquid mass transfer coefficient (k L a) of carbon monoxide (CO) in a batch cultivation system. The cell concentration (X), acetate concentration (C ace ), headspace gas (N co and [Formula: see text] ), dissolved CO concentration in the fermentation medium (C co ), and mass transfer rate (R) were simulated using a variety of k L a values. The simulated results showed excellent agreement with the experimental data for a k L a of 13/hr. The C co values decreased with increase in cultivation times, whereas the maximum mass transfer rate was achieved at the mid-log phase due to vigorous microbial CO consumption rate higher than R. The model suggested in this study may be applied to a variety of microbial systems involving gaseous substrates. Copyright © 2017 Elsevier Ltd. All rights reserved.
Numerical study of heat and mass transfer during evaporation of a turbulent binary liquid film
Directory of Open Access Journals (Sweden)
Khalal Larbi
2015-01-01
Full Text Available This paper deals with a computational study for analysing heat and mass exchanges in the evaporation of a turbulent binary liquid film (water-ethanol and water-methanol along a vertical tube. The film is in co-current with the dry air and the tube wall is subjected to a uniform heat flux. The effect of gas-liquid phase coupling, variable thermophysical properties and film vaporization are considered in the analysis. The numerical method applied solves the coupled governing equations together with the boundary and interfacial conditions. The algebraic systems of equations obtained are solved using the Thomas algorithm. The results concern the effects of the inlet liquid Reynolds number and inlet film composition on the intensity of heat and mass transfer. In this study, results obtained show that heat transferred through the latent mode is more pronounced when the concentration of volatile components is higher in the liquid mixture .The comparisons of wall temperature and accumulated mass evaporation rate with the literature results are in good agreement.
Impact of gamma-irradiation on some mass transfer driven operations in food processing
Energy Technology Data Exchange (ETDEWEB)
Rastogi, N.K. [Department of Food Engineering, Central Food Technological Research Institute, Mysore 570 020 (India)]. E-mail: nkrastogi@cftri.com
2005-08-01
The effect of gamma-irradiation pretreatment on some mass transfer driven operations such as dehydration, osmotic dehydration and rehydration, commonly used in food processing, was studied. Applied irradiation up to 12.0 kGy resulted in decrease in hardness of the samples, as indicated by texture analysis. The effective diffusion coefficients of water and solute determined for dehydration, osmotic dehydration as well as for rehydration using a Fickian diffusion model. The effective diffusion coefficients for water (in case of osmotic dehydration and dehydration) and solid diffusion (in case of osmotic dehydration) were found to increase exponentially with doses of gamma-irradiation (G) according to an equation of the form D=A exp(-B/G), where A and B are constants. Microstructures of irradiated-carrot samples revealed that the exposure of carrot to gamma irradiation resulted in the breakage of cell wall structure, thereby causing softening of irradiated samples and facilitating mass transfer during dehydration and osmotic dehydration. The rehydration characteristics showed that gamma-irradiated sample did not absorb as much water as control, probably due to loss of cell integrity.
Impact of gamma-irradiation on some mass transfer driven operations in food processing
International Nuclear Information System (INIS)
Rastogi, N.K.
2005-01-01
The effect of gamma-irradiation pretreatment on some mass transfer driven operations such as dehydration, osmotic dehydration and rehydration, commonly used in food processing, was studied. Applied irradiation up to 12.0 kGy resulted in decrease in hardness of the samples, as indicated by texture analysis. The effective diffusion coefficients of water and solute determined for dehydration, osmotic dehydration as well as for rehydration using a Fickian diffusion model. The effective diffusion coefficients for water (in case of osmotic dehydration and dehydration) and solid diffusion (in case of osmotic dehydration) were found to increase exponentially with doses of gamma-irradiation (G) according to an equation of the form D=A exp(-B/G), where A and B are constants. Microstructures of irradiated-carrot samples revealed that the exposure of carrot to gamma irradiation resulted in the breakage of cell wall structure, thereby causing softening of irradiated samples and facilitating mass transfer during dehydration and osmotic dehydration. The rehydration characteristics showed that gamma-irradiated sample did not absorb as much water as control, probably due to loss of cell integrity
A study of heat and mass transfer on magnetohydrodynamic (MHD flow of nanoparticles
Directory of Open Access Journals (Sweden)
Syed Tauseef Mohyud-Din
2018-03-01
Full Text Available Investigation of the flow, heat and mass transfer of a nanofluid over a suddenly moved flat plate is presented using Buongiorno's model. This study is different from some of the previous studies as the effects of Brownian motion and thermophoresis on nanoparticles volume fraction are passively controlled on the boundary rather than actively. The partial differential equations governing the flow are reduced to a system of nonlinear ordinary differential equations. Viable similarity transforms are used for this purpose. A well-known numerical scheme called Runge-Kutta-Fehlberg method coupled with shooting procedure has been used to find the solution of resulting system of equations. Discussions on the effects of different emerging parameters is provided using graphical aid. A table is also given that provides the results of different parameters on local Nusselt and Sherwood numbers. The passive control model can be used to control the boundary layer thickness as well as the rate of mass transfer at the wall. Keywords: Nanofluid, Brownian motion, Thermophoresis, Nusselt number, Sherwood number
Kharkov, N. S.
2017-11-01
Results of numerical modeling of the coupled nonstationary heat and mass transfer problem under conditions of a convective flow in facade system of a three-layer concrete panel for two different constructions (with ventilation channels and without) are presented. The positive effect of ventilation channels on the energy and humidity regime over a period of 12 months is shown. Used new method of replacement a solid zone (requiring specification of porosity and material structure, what complicates process of convergence of the solution) on quasi-solid in form of a multicomponent mixture (with restrictions on convection and mass fractions).
Experimental and computational investigations of heat and mass transfer of intensifier grids
International Nuclear Information System (INIS)
Kobzar, Leonid; Oleksyuk, Dmitry; Semchenkov, Yuriy
2015-01-01
The paper discusses experimental and numerical investigations on intensification of thermal and mass exchange which were performed by National Research Centre ''Kurchatov Institute'' over the past years. Recently, many designs of heat mass transfer intensifier grids have been proposed. NRC ''Kurchatov Institute'' has accomplished a large scope of experimental investigations to study efficiency of intensifier grids of various types. The outcomes of experimental investigations can be used in verification of computational models and codes. On the basis of experimental data, we derived correlations to calculate coolant mixing and critical heat flux mixing in rod bundles equipped with intensifier grids. The acquired correlations were integrated in subchannel code SC-INT.
Yasin, Muhammad; Park, Shinyoung; Jeong, Yeseul; Lee, Eun Yeol; Lee, Jinwon; Chang, In Seop
2014-10-01
This study proposed a submerged hollow fibre membrane bioreactor (HFMBR) system capable of achieving high carbon monoxide (CO) mass transfer for applications in microbial synthesis gas conversion systems. Hydrophobic polyvinylidene fluoride (PVDF) membrane fibres were used to fabricate a membrane module, which was used for pressurising CO in water phase. Pressure through the hollow fibre lumen (P) and membrane surface area per unit working volume of the liquid (A(S)/V(L)) were used as controllable parameters to determine gas-liquid volumetric mass transfer coefficient (k(L)a) values. We found a k(L)a of 135.72 h(-1) when P was 93.76 kPa and AS/VL was fixed at 27.5m(-1). A higher k(L)a of 155.16 h(-1) was achieved by increasing AS/VL to 62.5m(-1) at a lower P of 37.23 kPa. Practicality of HFMBR to support microbial growth and organic product formation was assessed by CO/CO2 fermentation using Eubacterium limosum KIST612. Copyright © 2014 Elsevier Ltd. All rights reserved.
Development of a model to determine mass transfer coefficient and oxygen solubility in bioreactors
Directory of Open Access Journals (Sweden)
Johnny Lee
2017-02-01
where T is in degree Kelvin, and the subscripts refer to degree Celsius; E, ρ, σ are properties of water. Furthermore, using data from published data on oxygen solubility in water, it was found that solubility bears a linear and inverse relationship with the mass transfer coefficient.
Effects of intraparticle heat and mass transfer during devolatilization of a single coal particle
Bliek, A.; Poelje, W.M.; van Swaaij, Willibrordus Petrus Maria; van Beckum, F.P.H.
1985-01-01
The objective of the present work is to elucidate the influence of intraparticle mass and heat transfer phenomena on the overall rate and product yields during devolatilization of a single coal particle in an inert atmosphere. To this end a mathematical model has been formulated which covers
Mass transfer experiments for the heat load during in-vessel retention of core melt
Energy Technology Data Exchange (ETDEWEB)
Park, Hae Kyun; Chung, Bum Jin [Dept. of Nuclear Engineering, Kyung Hee University, Seoul (Korea, Republic of)
2016-08-15
We investigated the heat load imposed on the lower head of a reactor vessel by the natural convection of the oxide pool in a severe accident. Mass transfer experiments using a CuSO{sub 4}–H{sub 2}SO{sub 4} electroplating system were performed based on the analogy between heat and mass transfer. The Ra′{sub H} of 10{sup 14} order was achieved with a facility height of only 0.1 m. Three different volumetric heat sources were compared; two had identical configurations to those previously reported, and the other was designed by the authors. The measured Nu's of the lower head were about 30% lower than those previously reported. The measured angular heat flux ratios were similar to those reported in existing studies except for the peaks appearing near the top. The volumetric heat sources did not affect the Nu of the lower head but affected the Nu of the top plate by obstructing the rising flow from the bottom.
Tiwari, Akhilesh; Kondjoyan, Alain; Fontaine, Jean-Pierre
2012-07-01
The phenomenon of heat and mass transfer by condensation of water vapour from humid air involves several key concepts in aerobic bioreactors. The high performance of bioreactors results from optimised interactions between biological processes and multiphase heat and mass transfer. Indeed in various processes such as submerged fermenters and solid-state fermenters, gas/liquid transfer need to be well controlled, as it is involved at the microorganism interface and for the control of the global process. For the theoretical prediction of such phenomena, mathematical models require heat and mass transfer coefficients. To date, very few data have been validated concerning mass transfer coefficients from humid air inflows relevant to those bioprocesses. Our study focussed on the condensation process of water vapour and developed an experimental set-up and protocol to study the velocity profiles and the mass flux on a small size horizontal flat plate in controlled environmental conditions. A closed circuit wind tunnel facility was used to control the temperature, hygrometry and hydrodynamics of the flow. The temperature of the active surface was controlled and kept isothermal below the dew point to induce condensation, by the use of thermoelectricity. The experiments were performed at ambient temperature for a relative humidity between 35-65% and for a velocity of 1.0 ms⁻¹. The obtained data are analysed and compared to available theoretical calculations on condensation mass flux.
Shi, Bobo; Zhou, Fubao
2014-01-01
The application of liquid nitrogen injection is an important technique in the field of coal mine fire prevention. However, the mechanism of heat and mass transfer of cryogenic nitrogen in the goaf porous medium has not been well accessed. Hence, the implementation of fire prevention engineering of liquid nitrogen roughly relied on an empirical view. According to the research gap in this respect, an experimental study on the heat and mass transfer of liquid nitrogen in coal porous media was pr...
Telu, Kelly H; Yan, Xinjian; Wallace, William E; Stein, Stephen E; Simón-Manso, Yamil
2016-03-15
The metabolite profiling of a NIST plasma Standard Reference Material (SRM 1950) on different liquid chromatography/mass spectrometry (LC/MS) platforms showed significant differences. Although these findings suggest caution when interpreting metabolomics results, the degree of overlap of both profiles allowed us to use tandem mass spectral libraries of recurrent spectra to evaluate to what extent these results are transferable across platforms and to develop cross-platform chemical signatures. Non-targeted global metabolite profiles of SRM 1950 were obtained on different LC/MS platforms using reversed-phase chromatography and different chromatographic scales (conventional HPLC, UHPLC and nanoLC). The data processing and the metabolite differential analysis were carried out using publically available (XCMS), proprietary (Mass Profiler Professional) and in-house software (NIST pipeline). Repeatability and intermediate precision showed that the non-targeted SRM 1950 profiling was highly reproducible when working on the same platform (relative standard deviation (RSD) HPLC, UHPLC and nanoLC) on the same platform. A substantial degree of overlap (common molecular features) was also found. A procedure to generate consistent chemical signatures using tandem mass spectral libraries of recurrent spectra is proposed. Different platforms rendered significantly different metabolite profiles, but the results were highly reproducible when working within one platform. Tandem mass spectral libraries of recurrent spectra are proposed to evaluate the degree of transferability of chemical signatures generated on different platforms. Chemical signatures based on our procedure are most likely cross-platform transferable. Published in 2016. This article is a U.S. Government work and is in the public domain in the USA.
The influence of mass transfer on solute transport in column experiments with an aggregated soil
Roberts, Paul V.; Goltz, Mark N.; Summers, R. Scott; Crittenden, John C.; Nkedi-Kizza, Peter
1987-06-01
The spreading of concentration fronts in dynamic column experiments conducted with a porous, aggregated soil is analyzed by means of a previously documented transport model (DFPSDM) that accounts for longitudinal dispersion, external mass transfer in the boundary layer surrounding the aggregate particles, and diffusion in the intra-aggregate pores. The data are drawn from a previous report on the transport of tritiated water, chloride, and calcium ion in a column filled with Ione soil having an average aggregate particle diameter of 0.34 cm, at pore water velocities from 3 to 143 cm/h. The parameters for dispersion, external mass transfer, and internal diffusion were predicted for the experimental conditions by means of generalized correlations, independent of the column data. The predicted degree of solute front-spreading agreed well with the experimental observations. Consistent with the aggregate porosity of 45%, the tortuosity factor for internal pore diffusion was approximately equal to 2. Quantitative criteria for the spreading influence of the three mechanisms are evaluated with respect to the column data. Hydrodynamic dispersion is thought to have governed the front shape in the experiments at low velocity, and internal pore diffusion is believed to have dominated at high velocity; the external mass transfer resistance played a minor role under all conditions. A transport model such as DFPSDM is useful for interpreting column data with regard to the mechanisms controlling concentration front dynamics, but care must be exercised to avoid confounding the effects of the relevant processes.
Curry, D. M.; Cox, J. E.
1972-01-01
Coupled nonlinear partial differential equations describing heat and mass transfer in a porous matrix are solved in finite difference form with the aid of a new iterative technique (the strongly implicit procedure). Example numerical results demonstrate the characteristics of heat and mass transport in a porous matrix such as a charring ablator. It is emphasized that multidimensional flow must be considered when predicting the thermal response of a porous material subjected to nonuniform boundary conditions.
Munasinghe, Pradeep Chaminda; Khanal, Samir Kumar
2012-10-01
In this study, the volumetric mass transfer coefficients (Ka) for CO were examined in a composite hollow fiber (CHF) membrane bioreactor. The mass transfer experiments were conducted at various inlet gas pressures (from 5 to 30 psig (34.5-206.8 kPa(g))) and recirculation flow rates (300, 600, 900, 1200 and 1500 mL/min) through CHF module. The highest Ka value of 946.6 1/h was observed at a recirculation rate of 1500 mL/min and at an inlet gas pressure of 30 psig(206.8 kPa(g)). The findings of this study confirm that the use of CHF membranes is effective and improves the efficiency CO mass transfer into the aqueous phase. Copyright © 2012 Elsevier Ltd. All rights reserved.
International Nuclear Information System (INIS)
Miyahara, S.; Sagawa, N.; Shimoyama, K.
1996-01-01
In the fuel pin failure accident of a liquid metal fast reactor, volatile fission products play an important role in the assessment of radiological consequences. Especially the radioisotopes of elemental iodine are important because of their high volatility and of the low permissible dose to human thyroid. The released iodines are known to be retained in the coolant sodium as sodium iodide due to the chemical affinity between alkali metals and halogens. However, the xenon and krypton released with iodines into the sodium pool as bubbles may influence the reaction rate of iodine with sodium during the bubble rising. So far, the only few experimental results have been available concerning the decontamination factor (DF: the ratio of the initial iodine mass in the mixed gas bubble to the released mass into the cover gas) of iodine in this phenomenon. Therefore, experimental and analytical studies were carried out to study the mass transfer of iodine from a xenon-iodine mixed gas bubble to the liquid sodium pool. In the experiments, the bubble was generated in the sodium pool by cracking a quartz ball which contains the xenon-iodine mixed gas and then, the mixed gas released into the argon cover gas was collected to determine the transferred iodine mass into the pool. A rising velocity of the bubble was measured by Chen-type void sensors arranged vertically in the pool. From the measured rising velocity and another observation of bubble behavior in simulated water experiments, it is found that the generated bubble breaks up into several smaller bubbles of spherical cap type during the rising period. Transferred iodine mass per unit initial bubble volume from the bubble to the sodium pool shows increases with increasing time and the initial iodine concentration. A mass transfer rate obtained by differentiating the transferred iodine mass with respect to the time indicates a rapid decrease just after the bubble generation and a slow decrease for the successive period
Minimization of thermal insulation thickness taking into account condensation on external walls
Directory of Open Access Journals (Sweden)
Nurettin Yamankaradeniz
2015-09-01
Full Text Available Condensation occurs in the inner layers of construction materials at whatever point the partial pressure of water vapor diffuses and reaches its saturation pressure. Condensation, also called sweating, damages materials, reduces thermal resistance, and by increasing the total heat transfer coefficient, results in unwanted events such as increased heat loss. This study applied minimization of thermal insulation thickness with consideration given to condensation in the external walls. The calculations of heat and mass transfers in the structure elements are expressed in a graphical form. While there was an increase in the required thermal insulation thickness subsequent to an increase in the internal environment’s temperature, relative humidity, and the external environment’s relative humidity, the required thickness decreased with an increase in the external environment’s temperature. The amount of water vapor transferred varied with internal or external conditions and the thickness of the insulation. A change in the vapor diffusion resistance of the insulation material can increase the risk of condensation on the internal or external surfaces of the insulation.
Energy Technology Data Exchange (ETDEWEB)
Randrup, J.
1979-07-01
This lecture discusses a theory for the transport of mass, charge, linear, and angular momentum and energy in damped nuclear collisions, as induced by multiple transfer of individual nucleons. 11 references.
Chen, X.; Le, T.; Ewing, D.; Ching, C. Y.
2016-12-01
The mass transfer to turbulent flow through back-to-back pipe bends arranged in a 180° configuration with different lengths of pipe between the bends was measured using a dissolving gypsum test section in water. The measurements were performed for bends with a radius of curvature of 1.5 times the pipe diameter ( D) at a Reynolds numbers of 70,000 and Schmidt number of 1280. The maximum mass transfer in the bends decreased from approximately 1.8 times the mass transfer in the upstream pipe when there was no separation distance between the bends to 1.7 times when there was a 1 D or 5 D length of pipe between the bends. The location of the maximum mass transfer was on the inner sidewall downstream of the second bend when there was no separation distance between the bends. This location changed to the inner wall at the beginning of the second bend when there was a 1 D long pipe between the bends, and to the inner sidewall at the end of the first bend when there was a 5 D long pipe between the bends.
Influence of mass transfer and chemical reaction on ozonation of azo dyes
Energy Technology Data Exchange (ETDEWEB)
Choi, I.S.; Wiesmann, U. [Dept. of Environmental Engineering, Technical Univ. of Berlin, Berlin (Germany)
2003-07-01
Azo dyes can be only mineralised by chemical oxidation. In this paper the oxidation of reactive black 5 (RB 5) and reactive orange 96 (RO 96) with concentrations between 35 and 5700 mgL{sup -1} (RB 5) and between 20 and 2050 mgL{sup -1} (RO 96) is investigated. A lab scale bubble column was used, which was gassed by a mixture of O{sub 2} and O{sub 3}. The oxidation rate was influenced by mass transfer for all dye concentrations used. For lower dye concentrations mass transfer alone was decisive for reaction rate showing an enhancement factor of E {approx} 1. However, in the region of higher dye concentrations, the slope of the decreasing ozone concentration inside the liquid boundary layer increases more and more with increasing dye concentration as a result of a chemical oxidation. Therefore, the enhancement factor depends on the kind and concentration of the azo dyes. For RB 5 as an diazo dye an enhancement factor of E = 9 was observed for 3800 mgL{sup -1}, RO 96 as a mono azo dye with a remarkable higher chemical oxidation rate shows an E = 17 already for 2050 mgL{sup -1}. (orig.)
Cao, Qing; Nastac, Laurentiu
2018-06-01
In this study, the Euler-Euler and Euler-Lagrange modeling approaches were applied to simulate the multiphase flow in the water model and gas-stirred ladle systems. Detailed comparisons of the computational and experimental results were performed to establish which approach is more accurate for predicting the gas-liquid multiphase flow phenomena. It was demonstrated that the Euler-Lagrange approach is more accurate than the Euler-Euler approach. The Euler-Lagrange approach was applied to study the effects of the free surface setup, injected bubble size, gas flow rate, and slag layer thickness on the slag-steel interaction and mass transfer behavior. Detailed discussions on the flat/non-flat free surface assumption were provided. Significant inaccuracies in the prediction of the surface fluid flow characteristics were found when the flat free surface was assumed. The variations in the main controlling parameters (bubble size, gas flow rate, and slag layer thickness) and their potential impact on the multiphase fluid flow and mass transfer characteristics (turbulent intensity, mass transfer rate, slag-steel interfacial area, flow patterns, etc.,) in gas-stirred ladles were quantitatively determined to ensure the proper increase in the ladle refining efficiency. It was revealed that by injecting finer bubbles as well as by properly increasing the gas flow rate and the slag layer thickness, the ladle refining efficiency can be enhanced significantly.
Peidou, Athina C.; Fotopoulos, Georgia; Pagiatakis, Spiros
2017-10-01
The main focus of this paper is to assess the feasibility of utilizing dedicated satellite gravity missions in order to detect large-scale solid mass transfer events (e.g. landslides). Specifically, a sensitivity analysis of Gravity Recovery and Climate Experiment (GRACE) gravity field solutions in conjunction with simulated case studies is employed to predict gravity changes due to past subaerial and submarine mass transfer events, namely the Agulhas slump in southeastern Africa and the Heart Mountain Landslide in northwestern Wyoming. The detectability of these events is evaluated by taking into account the expected noise level in the GRACE gravity field solutions and simulating their impact on the gravity field through forward modelling of the mass transfer. The spectral content of the estimated gravity changes induced by a simulated large-scale landslide event is estimated for the known spatial resolution of the GRACE observations using wavelet multiresolution analysis. The results indicate that both the Agulhas slump and the Heart Mountain Landslide could have been detected by GRACE, resulting in {\\vert }0.4{\\vert } and {\\vert }0.18{\\vert } mGal change on GRACE solutions, respectively. The suggested methodology is further extended to the case studies of the submarine landslide in Tohoku, Japan, and the Grand Banks landslide in Newfoundland, Canada. The detectability of these events using GRACE solutions is assessed through their impact on the gravity field.
Analysis of coupled mass transfer and sol-gel reaction in a two-phase system
Castelijns, H.J.; Huinink, H.P.; Pel, L.; Zitha, P.L.J.
2006-01-01
The coupled mass transfer and chemical reactions of a gel-forming compound in a two-phase system were studied in detail. Tetra-methyl-ortho-silicate (TMOS) is often used as a precursor in sol-gel chemistry to produce silica gels in aqueous systems. TMOS can also be mixed with many hydrocarbons
Transfer matrix in 1D Schroedinger problems with constant and position-dependent mass
International Nuclear Information System (INIS)
Perez-Alvarez, R.; Rodriguez-Coppola, H.
1987-10-01
We consider the transfer matrix method for obtaining properties of standard wells and barriers in one-dimensional Schroedinger problems with constant and position-dependent mass. We report the formulae for the energy levels of a well and the transmission coefficient of a barrier. We demonstrate the continuity between virtual bound states and bound states in a well of position-dependent mass and the relation between the zero energy gap states of a periodic potential problem with the corresponding energies of the non-periodic ones with transmission coefficient equal to one. The calculations were carried out for a wide class of potential profiles. (author). 30 refs, 2 figs
Yudov, Yu. V.
2018-03-01
A model is presented of the interphasic heat and mass transfer in the presence of noncondensable gases for the KORSAR/GP design code. This code was developed by FGUP NITI and the special design bureau OKB Gidropress. It was certified by Rostekhnadzor in 2009 for numerical substantiation of the safety of reactor installations with VVER reactors. The model is based on the assumption that there are three types of interphasic heat and mass transfer of the vapor component: vapor condensation or evaporation on the interphase under any thermodynamic conditions of the phases, pool boiling of the liquid superheated above the saturation temperature at the total pressure, and spontaneous condensation in the volume of gas phase supercooled below the saturation temperature at the vapor partial pressure. Condensation and evaporation on the interphase continuously occur in a two-phase flow and control the time response of the interphase heat and mass transfer. Boiling and spontaneous condensation take place only at the metastable condition of the phases and run at a quite high speed. The procedure used for calculating condensation and evaporation on the interphase accounts for the combined diffusion and thermal resistance of mass transfer in all regimes of the two-phase flow. The proposed approach accounts for, in a natural manner, a decrease in the rate of steam condensation (or generation) in the presence of noncondensing components in the gas phase due to a decrease (or increase) in the interphase temperature relative to the saturation temperature at the vapor partial pressure. The model of the interphase heat transfer also accounts for the processes of dissolution or release of noncondensing components in or from the liquid. The gas concentration at the interphase and on the saturation curve is calculated by the Henry law. The mass transfer coefficient in gas dissolution is based on the heat and mass transfer analogy. Results are presented of the verification of the
Directory of Open Access Journals (Sweden)
Andreas Velte
2017-08-01
Full Text Available Thermally-driven heat pumps can help to mitigate CO2 emissions by enhancing the efficiency of heating systems or by driving cooling systems with waste or solar heat. In order to make the thermally-driven systems more attractive for the end consumer, these systems need a higher power density. A higher power density can be achieved by intensifying the heat and mass transfer processes within the adsorption heat exchanger. For the optimization of this key component, a numerical model of the non-isothermal adsorption dynamics can be applied. The calibration of such a model can be difficult, since heat and mass transfer processes are strongly coupled. We present a measurement and simulation procedure that makes it possible to calibrate the heat transfer part of the numerical model separately from the mass transfer part. Furthermore, it is possible to identify the parts of the model that need to be improved. For this purpose, a modification of the well-known large temperature jump method is developed. The newly-introduced measurements are conducted under an inert N2 atmosphere, and the surface temperature of the sample is measured with an infrared sensor. We show that the procedure is applicable for two completely different types of samples: a loose grains configuration and a fibrous structure that is directly crystallized.
International Nuclear Information System (INIS)
Ali, Kashif; Iqbal, Muhammad Farooq; Ashraf, Muhammad; Akbar, Muhammad Zubair
2014-01-01
The paper deals with the study of heat and mass transfer in an unsteady viscous incompressible water-based nanofluid (containing Titanium dioxide nanoparticles) between two orthogonally moving porous coaxial disks with suction. A combination of iterative (successive over relaxation) and a direct method is employed for solving the sparse systems of linear algebraic equations arising from the FD discretization of the linearized self similar ODEs. It has been noticed that the rate of mass transfer at the disks decreases with the permeability Reynolds number whether the disks are approaching or receding. The findings of the present investigation may be beneficial for the electronic industry in maintaining the electronic components under effective and safe operational conditions
Turbulent heat/mass transfer at oceanic interfaces
Energy Technology Data Exchange (ETDEWEB)
Enstad, Lars Inge
2005-07-01
The thesis studies heat/mass transfer and uses various simulation techniques. A numerical method has been developed. 4 papers which describes the work, are included. In the first paper we look at such flow configuration where the flow is driven by a constant pressure gradient and the interface is cooled from above. Papers 2 and 3. 2: The effect of stable density stratification on turbulent vortical structures near an atmosphere-ocean interface driven by low wind shear. 3: Low shear turbulence structures beneath a gas-liquid interface under neutral and stable stratified conditions. A well known feature of the upper layer of the ocean is the presence of counter-rotating streamwise vorticity, so called Langmuir circulation. Earlier numerical investigations show that similar vortex structures appear on small scale induced by shear instability only. Short wave solar radiation may create a stable situation which affects the turbulence near the interface. In these papers we investigate such a flow situation by employing a uniform and constant shear stress at the interface together with a similar heat flux into the interface. In both articles we also use a two-point correlation to give a statistical representation of the streamwise vorticity. The spatial extent and intensity are decreased by stable stratification. In addition, in article 3, we find that the Reynolds stress is damped by stable stratification. This leads to an increased mean velocity since decreased Reynolds stress is compensated by a larger mean velocity gradient. The cospectra of the Reynolds stress in the spanwise direction show that the production of Reynolds stress is decreased at lower wave numbers and thus shifted to higher wave numbers in the presence of stable stratification. The streak structure created by the streamwise vorticity is disorganized by stable stratification. Article 4: A numerical study of a density interface using the General Ocean Turbulence Model (GOTM) coupled with a Navier Stokes
International Nuclear Information System (INIS)
Jang, Seok Pil; Kim, Sung Jin; Choi, Do Hyung
2000-01-01
As a mass flow controller is widely used in many manufacturing processes for controlling a mass flow rate of gas with accuracy of 1%, several investigators have tried to describe the heat transfer phenomena in a sensor tube of an MFC. They suggested a few analytic solutions and numerical models based on simple assumptions, which are physically unrealistic. In the present work, the heat transfer phenomena in the sensor tube of the MFC are studied by using both experimental and numerical methods. The numerical model is introduced to estimate the temperature profile in the sensor tube as well as in the gas stream. In the numerical model, the conjugate heat transfer problem comprising the tube wall and the gas stream is analyzed to fully understand the heat transfer interaction between the sensor tube and the fluid stream using a single domain approach. This numerical model is further verified by experimental investigation. In order to describe the transport of heat energy in both the flow region and the sensor tube, the Nusselt number at the interface between the tube wall and the gas stream as well as heatlines is presented from the numerical solution
Energy Technology Data Exchange (ETDEWEB)
Gosnell, Natalie M.; Mathieu, Robert D. [Department of Astronomy, University of Wisconsin - Madison, 475 N. Charter St., Madison, WI 53706 (United States); Geller, Aaron M. [Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Rd, Evanston, IL 60208 (United States); Sills, Alison [Department of Physics and Astronomy, McMaster University, 1280 Main St. W, Hamilton, ON L8S 4M1 (Canada); Leigh, Nathan [Department of Physics, University of Alberta, CCIS 4-183, Edmonton, AB T6G 2E1 (Canada); Knigge, Christian, E-mail: gosnell@astro.wisc.edu [School of Physics and Astronomy, University of Southampton, Highfield, Southampton, SO17 IBJ (United Kingdom)
2014-03-01
Several possible formation pathways for blue straggler stars have been developed recently, but no one pathway has yet been observationally confirmed for a specific blue straggler. Here we report the first findings from a Hubble Space Telescope Advanced Camera for Surveys/Solar Blind Channel far-UV photometric program to search for white dwarf companions to blue straggler stars. We find three hot and young white dwarf companions to blue straggler stars in the 7 Gyr open cluster NGC 188, indicating that mass transfer in these systems ended less than 300 Myr ago. These companions are direct and secure observational evidence that these blue straggler stars were formed through mass transfer in binary stars. Their existence in a well-studied cluster environment allows for observational constraints of both the current binary system and the progenitor binary system, mapping the entire mass transfer history.
Numerical analysis of heat and mass transfer for water recovery in an evaporative cooling tower
Lee, Hyunsub; Son, Gihun
2017-11-01
Numerical analysis is performed for water recovery in an evaporative cooling tower using a condensing heat exchanger, which consists of a humid air channel and an ambient dry air channel. The humid air including water vapor produced in an evaporative cooling tower is cooled by the ambient dry air so that the water vapor is condensed and recovered to the liquid water. The conservation equations of mass, momentum, energy and vapor concentration in each fluid region and the energy equation in a solid region are simultaneously solved with the heat and mass transfer boundary conditions coupled to the effect of condensation on the channel surface of humid air. The present computation demonstrates the condensed water film distribution on the humid air channel, which is caused by the vapor mass transfer between the humid air and the colder water film surface, which is coupled to the indirect heat exchange with the ambient air. Computations are carried out to predict water recovery rate in parallel, counter and cross-flow type heat exchangers. The effects of air flow rate and channel interval on the water recovery rate are quantified.
Mass balance model parameter transferability on a tropical glacier
Gurgiser, Wolfgang; Mölg, Thomas; Nicholson, Lindsey; Kaser, Georg
2013-04-01
The mass balance and melt water production of glaciers is of particular interest in the Peruvian Andes where glacier melt water has markedly increased water supply during the pronounced dry seasons in recent decades. However, the melt water contribution from glaciers is projected to decrease with appreciable negative impacts on the local society within the coming decades. Understanding mass balance processes on tropical glaciers is a prerequisite for modeling present and future glacier runoff. As a first step towards this aim we applied a process-based surface mass balance model in order to calculate observed ablation at two stakes in the ablation zone of Shallap Glacier (4800 m a.s.l., 9°S) in the Cordillera Blanca, Peru. Under the tropical climate, the snow line migrates very frequently across most of the ablation zone all year round causing large temporal and spatial variations of glacier surface conditions and related ablation. Consequently, pronounced differences between the two chosen stakes and the two years were observed. Hourly records of temperature, humidity, wind speed, short wave incoming radiation, and precipitation are available from an automatic weather station (AWS) on the moraine near the glacier for the hydrological years 2006/07 and 2007/08 while stake readings are available at intervals of between 14 to 64 days. To optimize model parameters, we used 1000 model simulations in which the most sensitive model parameters were varied randomly within their physically meaningful ranges. The modeled surface height change was evaluated against the two stake locations in the lower ablation zone (SH11, 4760m) and in the upper ablation zone (SH22, 4816m), respectively. The optimal parameter set for each point achieved good model skill but if we transfer the best parameter combination from one stake site to the other stake site model errors increases significantly. The same happens if we optimize the model parameters for each year individually and transfer
Effect of surfactant on single drop mass transfer for extraction of aromatics from lubricating oils
Izza, H.; Ben Abdessalam, S.; Korichi, M.
2018-03-01
Solvent extraction is an effective method for the reduction of the content of aromatic of lubricating oil. Frequently, with phenol, furfural, the NMP (out of N-methyl pyrrolidone). The power solvent and the selectivity can be still to increase while using surfactant as additive which facilitates the separation of phase and increases the yeild in raffinat. Liquid-liquid mass transfer coefficients for single freely rising drops in the presence of surfactant in an extraction column have been investigated. The surfactant used in this study was sodium lauryl ether sulfate (SLES). The experiments were performed by bubbling a solvent as a series of individual drops from the top of the column containing furfural-SLES solution. The column used in this experiment was made from glass with 17 mm inner diameter and a capacity of 125ml. The effects of the concentration of surfactant on the overall coefficient of mass transfer was investigated.
Natural convection mass transfer on a vertical steel structure submerged in a molten aluminum pool
International Nuclear Information System (INIS)
Cheung, F.B.; Yang, B.C.; Shiah, S.W.; Cho, D.H.; Tan, M.J.
1995-01-01
The process of dissolution mass transport along a vertical steel structure submerged in a large molten aluminum pool is studied theoretically. A mathematical model is developed from the conservation laws and thermodynamic principles, taking full account of the density variation in the dissolution boundary layer due to concentration differences. Also accounted for are the influence of the solubility of the wall material on species transfer and the motion of the solid/liquid interface at the dissolution front. The governing equations are solved by a combined analytical-numerical technique to determine the characteristics of the dissolution boundary layer and the rate of natural convection mass transfer. Based upon the numerical results, a correlation for the average Sherwood number is obtained. It is found that the Sherwood number depends strongly on the saturated concentration of the substrate at the moving dissolution front but is almost independent of the freestream velocity
Minimal Length Effects on Tunnelling from Spherically Symmetric Black Holes
Directory of Open Access Journals (Sweden)
Benrong Mu
2015-01-01
Full Text Available We investigate effects of the minimal length on quantum tunnelling from spherically symmetric black holes using the Hamilton-Jacobi method incorporating the minimal length. We first derive the deformed Hamilton-Jacobi equations for scalars and fermions, both of which have the same expressions. The minimal length correction to the Hawking temperature is found to depend on the black hole’s mass and the mass and angular momentum of emitted particles. Finally, we calculate a Schwarzschild black hole's luminosity and find the black hole evaporates to zero mass in infinite time.
International Nuclear Information System (INIS)
Sun, Zhongwei; Wang, Shengwei; Zhou, Qulan; Hui, Shi'en
2010-01-01
This paper presents a new liquid-screen gas-liquid two-phase flow pattern with discarded carbide slag as the liquid sorbent of sulfur dioxide (SO 2 ) in a wet flue gas desulfurization (WFGD) system. On the basis of experimental data, the correlations of the desulfurization efficiency with flue gas flow rate, slurry flow rate, pH value of slurry and liquid-gas ratio were investigated. A non-dimensional empirical model was developed which correlates the mass transfer coefficient with the liquid Reynolds number, gas Reynolds number and liquid-gas ratio (L/G) based on the available experimental data. The kinetic reaction between the SO 2 and the carbide slag depends on the pressure distribution in this desulfurizing tower, gas liquid flow field, flue gas component, pH value of slurry and liquid-gas ratio mainly. The transient gas-liquid mass transfer involving with chemical reaction was quantified by measuring the inlet and outlet SO 2 concentrations of flue gas as well as the characteristics of the liquid-screen two-phase flow. The mass transfer model provides a necessary quantitative understanding of the hydration kinetics of sulfur dioxide in the liquid-screen flue gas desulfurization system using discarded carbide slag which is essential for the practical application. (author)
Milly, P J; Toledo, R T; Chen, J; Kazem, B
2007-11-01
Ultraviolet (UV)-induced chemical reactions and inactivation of microorganisms in transparent and opaque fluids are strongly dependent upon the homogenous exposure of the target species to the UV irradiation. Current UV technologies used in water disinfection and food preservation applications have limited efficacy due to suspended particles shading target species. An Ultraviolet-Shockwave Power Reactor (UV-SPR) consisting of an inner rotating rotor and a stationary quartz housing and 2 end plates was used to induce 'controlled cavitation.' Eight UV low-pressure mercury lamps spaced uniformly were installed lengthwise around the quartz housing periphery. A KI to I(3) (-)chemical dosimeter for UV was used to quantify photons received by fluid in the annular space of the SPR. UV dose (J/m(2)) increased from 97 J/m(2) at 0 rpm to over 700 J/m(2) for SPR speeds above 2400 rpm. Inactivation of E. coli 25922 in apple juice and skim milk in the UV-SPR at exit temperatures below 45 degrees C was greater than 4.5 and 3 logs, respectively. The UV-SPR system proved successful in increasing the mass transfer of transparent and opaque fluid to the UV irradiated surface.
Gravitino problem in minimal supergravity inflation
Energy Technology Data Exchange (ETDEWEB)
Hasegawa, Fuminori [Institute for Cosmic Ray Research, The University of Tokyo, Kashiwa, Chiba 277-8582 (Japan); Mukaida, Kyohei [Kavli IPMU (WPI), UTIAS, The University of Tokyo, Kashiwa, Chiba 277-8583 (Japan); Nakayama, Kazunori [Department of Physics, Faculty of Science, The University of Tokyo, Bunkyo-ku, Tokyo 133-0033 (Japan); Terada, Takahiro, E-mail: terada@kias.re.kr [School of Physics, Korea Institute for Advanced Study (KIAS), Seoul 02455 (Korea, Republic of); Yamada, Yusuke [Stanford Institute for Theoretical Physics and Department of Physics, Stanford University, Stanford, CA 94305 (United States)
2017-04-10
We study non-thermal gravitino production in the minimal supergravity inflation. In this minimal model utilizing orthogonal nilpotent superfields, the particle spectrum includes only graviton, gravitino, inflaton, and goldstino. We find that a substantial fraction of the cosmic energy density can be transferred to the longitudinal gravitino due to non-trivial change of its sound speed. This implies either a breakdown of the effective theory after inflation or a serious gravitino problem.
Gravitino problem in minimal supergravity inflation
Directory of Open Access Journals (Sweden)
Fuminori Hasegawa
2017-04-01
Full Text Available We study non-thermal gravitino production in the minimal supergravity inflation. In this minimal model utilizing orthogonal nilpotent superfields, the particle spectrum includes only graviton, gravitino, inflaton, and goldstino. We find that a substantial fraction of the cosmic energy density can be transferred to the longitudinal gravitino due to non-trivial change of its sound speed. This implies either a breakdown of the effective theory after inflation or a serious gravitino problem.
nTiO_2 mass transfer and deposition behavior in an aquatic environment
International Nuclear Information System (INIS)
Wei, Xiuzhen; He, Junhui; Wang, Meng; Fang, Jinfeng; Chen, Jinyuan; Lv, Bosheng
2016-01-01
Nano-TiO_2 (nTiO_2) is widely used in industry, and some of it is inevitably released into natural aquatic environments. nTiO_2 can be deposited on the streambed or transported along the stream and streambed, and it can also undergo exchange-transfer processes in these systems. The behavior of nTiO_2 in rivers includes deposition-transfer processes in the stream and exchange-transfer processes between the stream and streambed. In this work, the deposition, mass transfer, exchange, and aggregation behavior of nTiO_2 in a simulated river were studied as a function of the solution pH, stream velocity, and anionic, cationic, and neutral surfactant concentrations. In these experiments, a recirculating flume was used to simulate a natural stream. The nTiO_2 deposition and aggregation phenomena in the river and streambed were characterized. Of the three surfactants studied, the anionic surfactant enhanced the nTiO_2 stability in the river and limited its aggregation most effectively, resulting in slow nTiO_2 deposition and nTiO_2 transport over long distances. This study provides information about nanoparticle transport phenomena in simulated natural aquatic systems.
Mass transfer behavior of tritium from air to water through the water surface
International Nuclear Information System (INIS)
Takata, Hiroki; Nishikawa, Masabumi; Kamimae, Kozo
2005-01-01
It is anticipated that a certain amount of tritiated water exists in the atmosphere of tritium handling facilities, and it is recognized that the hazardous potential of tritiated water is rather high. Then, it is important to grasp the behavior of tritiated water for preserving of the radiation safety. The mass transfer behavior of tritium from air to water through the water surface was discussed in this study. The evaporation rate of water and the condensation rate of water were experimentally examined from measurement of change of the weight of distilled water. The tritium transfer rate from the tritiated water in air to the distilled water was also experimentally examined by using a liquid scintillation counter. Experimental results about change of tritium level in a small beaker placed in the atmosphere with tritiated water showed that diffusion of tritium in water and gas flow in the atmosphere gives considerable effect on tritium transfer. The estimation method of the tritium transfer made in this study was applied to explain the data at The Japan Atomic Power Company second power station at Tsuruga and good agreement was obtained. (author)
The phenomenon of microscale flow and mass transfer in medicinal herb materials
Energy Technology Data Exchange (ETDEWEB)
Yang, J.H.; Di, Q.Q.; Sun, M.D. [Tianjin Univ., Tianjin (China). School of Mechanical Engineering; Zhang, T.J.; Gong, S.X. [Tianjin Inst. of Pharmaceutical Research, Tianjin (China)
2008-07-01
Microwave assisted extraction (MAE) is a combination of a microwave technique and conventional solvent extraction used in the modernization of traditional Chinese medicine. The effective component of medicinal herbs is mostly cellular material which can be released via solvent extraction. The material is diffused to solvents via the porous membrane wall. The structure of herb morphology and characteristics of the solute's molecular weight play an important role in the extraction process of target compounds. Astragalus pieces were chosen for this study in which an ultra-filtration membrane method was used to determine the molecular weight distribution characteristics of Astragalus water extraction liquid in the process of MAE. The fine structure of matrix materials was also characterized by scanning election microscopy (SEM). The phenomenon of mass flow and mass transfer in the plant porous media was discussed along with the enhancement mechanism of microwave field on medicinal plant solvent extraction. The results showed that the water-soluble components in the parenchyma cells of Astragalus pieces pass through the plasmodesma with a diameter of 10 nm to adjacent cell, then through an aperture with a diameter of 0.1 {mu}m to 1 {mu}m into a trachea with a diameter of about 10 {mu}m. The water-soluble components then come onto the surface of matrix material and the main solution via the trachea. The main mass transfer occurs by the trachea and its aperture. It was concluded that in order to promote the dissolution of effective components in medicinal herb in the extraction process, a suitable extraction technology is needed to maintain the permeability of transportation tissue and parenchyma in materials. 11 refs., 1 tab., 3 figs.
Modelling of the processes of heat and mass transfer in adiabatic steam and drop flows
International Nuclear Information System (INIS)
Andrizhievskij, A.A.; Mikhalevich, A.A.; Nesterenko, V.B.; Trifonov, A.G.
1983-01-01
The mathematical models for investigating the local and integral characteristics of heat and mass transfer processes during simultaneous motion of adiabatic steam and drop flow and a flux of impurity particles are given. The mathematical model is constrUcted on the basis of one-dimensional stationary eqUations of conservation of mass, thermal energy and momentum of liquid and vapor phases. Dispersion composition of condensed moisture is described by the Nukiyama-Tanasava distribution function formed taking into account the Veber number critical value. Equations of motion and mass balance conservation for impurity particles are included into the mathematical model. These equations are considered as additional inactive phase
Analysis of heat and mass transfers in two-phase flow by coupling optical diagnostic techniques
Energy Technology Data Exchange (ETDEWEB)
Lemaitre, P.; Porcheron, E. [Institut de Radioprotection et de Surete Nucleaire, Saclay (France)
2008-08-15
During the course of a hypothetical accident in a nuclear power plant, spraying might be actuated to reduce static pressure in the containment. To acquire a better understanding of the heat and mass transfers between a spray and the surrounding confined gas, non-intrusive optical measurements have to be carried out simultaneously on both phases. The coupling of global rainbow refractometry with out-of-focus imaging and spontaneous Raman scattering spectroscopy allows us to calculate the local Spalding parameter B{sub M}, which is useful in describing heat transfer associated with two-phase flow. (orig.)
Analysis of heat and mass transfers in two-phase flow by coupling optical diagnostic techniques
International Nuclear Information System (INIS)
Lemaitre, P.; Porcheron, E.
2008-01-01
During the course of a hypothetical accident in a nuclear power plant, spraying might be actuated to reduce static pressure in the containment. To acquire a better understanding of the heat and mass transfers between a spray and the surrounding confined gas, non-intrusive optical measurements have to be carried out simultaneously on both phases. The coupling of global rainbow refractometry with out-of-focus imaging and spontaneous Raman scattering spectroscopy allows us to calculate the local Spalding parameter B M , which is useful in describing heat transfer associated with two-phase flow. (orig.)
Heat-and-mass transfer during a laminar dissociating gas flow in eccentric annular channels
International Nuclear Information System (INIS)
Besedina, T.V.; Udot, A.V.; Yakushev, A.P.
1987-01-01
An algorithm to calculate heat-and-mass transfer processes during dissociating gas laminar flow in an eccentric annular channels is considered. Analytical solutions of the heat transfer equations for a rod clodding and gap with boundary conditions of conjugation of temperatures and heat fluxes have been used to determine temperature field. This has made it possible to proceed from slution of the conjugate problem to solution of the equation of energy only for the coolant. The results of calculation of temperature distribution along the cladding for different values of its eccentricity and thermal conductivity coefficient both for the case of frozen flow and in the presence of chemical reactions in the flow are given. When calculating temperatures with conjugation boundary conditions temperature gradients in azimuthal direction are far less and heat transfer in concentration diffusion is carried out mainly in radial direction
International Nuclear Information System (INIS)
1986-07-01
The specialists' meeting on ''Heat and Mass Transfer in the Reactor Cover Gas'' was held at Harwell, the United Kingdom, on 8-10 October 1985. It was attended by 24 participants from all IWGFR member-countries: France, the Federal Republic of Germany, India, Italy, Japan, the Union of Soviet Socialist Republics, the United Kingdom and the United States. The meeting was presided over by Dr K. Eickhoff of the United Kingdom. The following topical areas were reviewed and discussed during the meeting: 1. National review presentations on the status of activities on heat and mass transfer in the reactor cover gas - 2 papers; 2. Aerosol dynamics - 4 papers; 3. Aerosol trapping - 2 papers; 4. Heat and mass transfer through cover gas in annuli - 3 papers; 5. Radiative properties - 4 papers; 6. Modelling of cover gas - 4 papers. A separate abstract was prepared for each of these papers. On the basis of papers presented and discussed by participants, session summaries and conclusions were drafted on the above topical areas. These summaries, as well as general conclusions and recommendations of the meeting were reviewed and agreed upon by consensus at the end of the meeting
Application of Lattice Boltzmann Methods in Complex Mass Transfer Systems
Sun, Ning
. When the inhomogeneity is small, dendrites form mainly under high current densities, in which the mass transfer is dominated by electromigration; when the inhomogeneity is very large, dendrites may form under both high and low current densities, which is dominated by electromigration in high current density and by surface reactivity in low current density. We show that the critical current density for dendrite formation is sensitive to surface inhomogeneous reactivity and the onset time of dendrite formation is sensitive to the initial roughness of electrode. A new analysis method is introduced, which can predict the formation of dendrites in batteries at a very early stage even before large dendrites form. Charge/discharge cyclic properties of the system are also studied, which shows that electrode roughness will increase during cycles and the break-off of dendritic structures is inevitable once big dendrites form; however, it is possible to minimize the amount of break-off materials by optimizing the rate of discharge. (3) The LBM is also used to simulate intercalation reactions in a Li-Ion battery with graphite as anode and pure Li metal as counter electrode. Both galvanostatic and potentiostatic conditions were studied. The relation between operation parameters (current and potential) and electrode parameters (porosity, thickness and diffusivity) and plating times were discussed. Different equilibrium potentials forms (empirical fitting, fitting of SONY 18650 cell, and staged profiles) were also compared. By modifying the morphology of electrode with a density gradient, it was shown that much better electrode performance can be obtained, which can be helpful for the designing and manufacturing of better batteries. (4) The transdermal drug delivery system is also simulated by using LBM. Two kinds of transdermal structures are discussed: "brick and mortar" structure and a simple homogenized structure. It is demonstrated that the homogenized system is able to obtain
Micro-scale mass-transfer variations during electrodeposition
Energy Technology Data Exchange (ETDEWEB)
Sutija, D.P.
1991-08-01
Results of two studies on micro-scale mass-transfer enhancement are reported: (1) Profiled cross-sections of striated zinc surfaces deposited in laminar channel flow were analyzed with fast-fourier transforms (FFT) to determine preferred striation wavelengths. Striation frequency increases with current density until a minimum separation between striae of 150 {mu}m is reached. Beyond this point, independent of substrate used, striae meld together and form a relatively smooth, nodular deposit. Substrates equipped with artificial micron-sized protrusions result in significantly different macro-morphology in zinc deposits. Micro-patterned electrodes (MPE) with hemispherical protrusions 5 {mu}m in diameter yield thin zinc striae at current densities that ordinarily produce random nodular deposits. MPEs with artificial hemi-cylinders, 2.5 {mu}m in height and spaced 250 {mu}m apart, form striae with a period which matches the spacing of micron-sized ridges. (2) A novel, corrosion-resistant micromosaic electrode was fabricated on a silicon wafer. Measurements of mass-transport enhancement to a vertical micromosaic electrode caused by parallel bubble streams rising inside of the diffusion boundary-layer demonstrated the presence of two co-temporal enhancement mechanisms: surface-renewal increases the limiting current within five bubble diameters of the rising column, while bubble-induced laminar flows cause weaker enhancement over a much broader swath. The enhancement caused by bubble curtains is predicted accurately by linear superposition of single-column enhancements. Two columns of smaller H{sub 2} bubbles generated at the same volumetric rate as a single column of larger bubbles cause higher peak and far-field enhancements. 168 refs., 96 figs., 6 tabs.
Aziz, Asim; Siddique, J. I.; Aziz, Taha
2014-01-01
In this paper, a simplified model of an incompressible fluid flow along with heat and mass transfer past a porous flat plate embedded in a Darcy type porous medium is investigated. The velocity, thermal and mass slip conditions are utilized that has not been discussed in the literature before. The similarity transformations are used to transform the governing partial differential equations (PDEs) into a nonlinear ordinary differential equations (ODEs). The resulting system of ODEs is then reduced to a system of first order differential equations which was solved numerically by using Matlab bvp4c code. The effects of permeability, suction/injection parameter, velocity parameter and slip parameter on the structure of velocity, temperature and mass transfer rates are examined with the aid of several graphs. Moreover, observations based on Schmidt number and Soret number are also presented. The result shows, the increase in permeability of the porous medium increase the velocity and decrease the temperature profile. This happens due to a decrease in drag of the fluid flow. In the case of heat transfer, the increase in permeability and slip parameter causes an increase in heat transfer. However for the case of increase in thermal slip parameter there is a decrease in heat transfer. An increase in the mass slip parameter causes a decrease in the concentration field. The suction and injection parameter has similar effect on concentration profile as for the case of velocity profile. PMID:25531301
Aziz, Asim; Siddique, J I; Aziz, Taha
2014-01-01
In this paper, a simplified model of an incompressible fluid flow along with heat and mass transfer past a porous flat plate embedded in a Darcy type porous medium is investigated. The velocity, thermal and mass slip conditions are utilized that has not been discussed in the literature before. The similarity transformations are used to transform the governing partial differential equations (PDEs) into a nonlinear ordinary differential equations (ODEs). The resulting system of ODEs is then reduced to a system of first order differential equations which was solved numerically by using Matlab bvp4c code. The effects of permeability, suction/injection parameter, velocity parameter and slip parameter on the structure of velocity, temperature and mass transfer rates are examined with the aid of several graphs. Moreover, observations based on Schmidt number and Soret number are also presented. The result shows, the increase in permeability of the porous medium increase the velocity and decrease the temperature profile. This happens due to a decrease in drag of the fluid flow. In the case of heat transfer, the increase in permeability and slip parameter causes an increase in heat transfer. However for the case of increase in thermal slip parameter there is a decrease in heat transfer. An increase in the mass slip parameter causes a decrease in the concentration field. The suction and injection parameter has similar effect on concentration profile as for the case of velocity profile.
Model for heat and mass transfer in freeze-drying of pellets.
Trelea, Ioan Cristian; Passot, Stéphanie; Marin, Michèle; Fonseca, Fernanda
2009-07-01
Lyophilizing frozen pellets, and especially spray freeze-drying, have been receiving growing interest. To design efficient and safe freeze-drying cycles, local temperature and moisture content in the product bed have to be known, but both are difficult to measure in the industry. Mathematical modeling of heat and mass transfer helps to determine local freeze-drying conditions and predict effects of operation policy, and equipment and recipe changes on drying time and product quality. Representative pellets situated at different positions in the product slab were considered. One-dimensional transfer in the slab and radial transfer in the pellets were assumed. Coupled heat and vapor transfer equations between the temperature-controlled shelf, the product bulk, the sublimation front inside the pellets, and the chamber were established and solved numerically. The model was validated based on bulk temperature measurement performed at two different locations in the product slab and on partial vapor pressure measurement in the freeze-drying chamber. Fair agreement between measured and calculated values was found. In contrast, a previously developed model for compact product layer was found inadequate in describing freeze-drying of pellets. The developed model represents a good starting basis for studying freeze-drying of pellets. It has to be further improved and validated for a variety of product types and freeze-drying conditions (shelf temperature, total chamber pressure, pellet size, slab thickness, etc.). It could be used to develop freeze-drying cycles based on product quality criteria such as local moisture content and glass transition temperature.
Energy Technology Data Exchange (ETDEWEB)
Haddad, Djamel; Benmoussa, Hocine [Laboratory (LESEI), Faculty of Engineering, University of Batna (Algeria); Bourmada, Noureddine; Oulmi, Kafia [Laboratory LCCE, Faculty of Science, University of Batna (Algeria); Mahmah, Bouziane; Belhamel, Maiouf [CDER, BP, 62 Avenue-Observatoire, Bouzareah, Alger (Algeria)
2009-06-15
The objective of our study is to quantify the mass water transferred by various modes: diffusion, convection and migration. For the water transfer, the principal forces considered in the model are, the convection force, the osmotic force (i.e. diffusion) and the electric force (migration). The first of these forces results from a pressure gradient, the second of a concentration gradient and the third of a protons' migration from the anode to the cathode, which has an effect on the dipole of the water molecules (resistance force to the advancement). The numerical tool used to solve the equations' system is the finite element method. The results obtained numerically considering this method are concentration profiles and concentration variation with time and membrane thickness. These results illustrate the contribution of each mass transfer mode. (author)
Fymat, A. L.
1976-01-01
The paper studies the inversion of the radiative transfer equation describing the interaction of electromagnetic radiation with atmospheric aerosols. The interaction can be considered as the propagation in the aerosol medium of two light beams: the direct beam in the line-of-sight attenuated by absorption and scattering, and the diffuse beam arising from scattering into the viewing direction, which propagates more or less in random fashion. The latter beam has single scattering and multiple scattering contributions. In the former case and for single scattering, the problem is reducible to first-kind Fredholm equations, while for multiple scattering it is necessary to invert partial integrodifferential equations. A nonlinear minimization search method, applicable to the solution of both types of problems has been developed, and is applied here to the problem of monitoring aerosol pollution, namely the complex refractive index and size distribution of aerosol particles.
Directory of Open Access Journals (Sweden)
Zhang Yuan
2016-01-01
Full Text Available A self-designed experimental installation for transient heat transfer in the modelling surrounding rock mass of high geothermal roadways was elaborated in this paper. By utilizing the new installation, the temperature variation rules in surrounding rock mass of the high geothermal roadway during mechanical ventilation were studied. The results show that the roadway wall temperature decreases dramatically at the early stage of ventilation, and the temperature at every position of the surrounding rock mass is decreasing constantly with time passing by. From roadway wall to deep area, the temperature gradually increases until reaching original rock temperature. The relationship between dimensionless temperature and dimensionless radius demonstrates approximately exponential function. Meanwhile, the temperature disturbance range in the simulated surrounding rock mass extends gradually from the roadway wall to deep area in the surrounding rock mass. Besides, as the air velocity increases, heat loss in the surrounding rock mass rises and the ratio of temperature reduction becomes larger, the speed of disturbance range expansion also gets faster.
User's Manual for the FEHM Application-A Finite-Element Heat- and Mass-Transfer Code
Energy Technology Data Exchange (ETDEWEB)
George A. Zyvoloski; Bruce A. Robinson; Zora V. Dash; Lynn L. Trease
1997-07-07
This document is a manual for the use of the FEHM application, a finite-element heat- and mass-transfer computer code that can simulate nonisothermal multiphase multicomponent flow in porous media. The use of this code is applicable to natural-state studies of geothermal systems and groundwater flow. A primary use of the FEHM application will be to assist in the understanding of flow fields and mass transport in the saturated and unsaturated zones below the proposed Yucca Mountain nuclear waste repository in Nevada. The equations of heat and mass transfer for multiphase flow in porous and permeable media are solved in the FEHM application by using the finite-element method. The permeability and porosity of the medium are allowed to depend on pressure and temperature. The code also has provisions for movable air and water phases and noncoupled tracers; that is, tracer solutions that do not affect the heat- and mass-transfer solutions. The tracers can be passive or reactive. The code can simulate two-dimensional, two-dimensional radial, or three-dimensional geometries. In fact, FEHM is capable of describing flow that is dominated in many areas by fracture and fault flow, including the inherently three-dimensional flow that results from permeation to and from faults and fractures. The code can handle coupled heat and mass-transfer effects, such as boiling, dryout, and condensation that can occur in the near-field region surrounding the potential repository and the natural convection that occurs through Yucca Mountain due to seasonal temperature changes. The code is also capable of incorporating the various adsorption mechanisms, ranging from simple linear relations to nonlinear isotherms, needed to describe the very complex transport processes at Yucca Mountain. This report outlines the uses and capabilities of the FEHM application, initialization of code variables, restart procedures, and error processing. The report describes all the data files, the input data
International Nuclear Information System (INIS)
Akram, Safia; Nadeem, S.; Hussain, Anwar
2014-01-01
In the present analysis we discussed the influence of heat and mass transfer on the peristaltic flow of a Bingham in an inclined magnetic field and channel with different wave forms. The governing two dimensional equations of momentum, heat and mass transfer are simplified under the assumptions of long wavelength and low Reynolds number approximation. The exact solutions of momentum, heat and mass transfer are calculated. Finally, graphical behaviors of various physical parameters are also discussed through the graphical behavior of pressure rise, pressure gradient, temperature concentration and stream functions. - Highlights: • Combine effects of heat and mass transfer on peristaltic flow problem is discussed. • Effects of inclined magnetic field and channel on new fluid model are discussed. • Effects of different wave forms are also discussed in the present flow problem
Mass transfer in water-saturated concretes
International Nuclear Information System (INIS)
Atkinson, A.; Claisse, P.A.; Harris, A.W.; Nickerson, A.K.
1990-01-01
Cements and concretes are often considered as components of barriers for the containment of radioactive waste. The performance of such materials as mainly physical barriers to the transport of dissolved radionuclides depends on the mass transfer characteristics of the material. In particular the diffusion and sorption behavior of the radionuclides and the water permeability are important. These parameters also influence how the chemistry of the concrete is imposed on the repository. In addition, the transport of gas through concrete controls the way in which gases escape from the repository. Diffusion and gas transport have been measured in a variety of cementitious materials, covering both structural concretes and cementitious backfills; all possible repository construction materials. Measurements have been made using aqueous iodide, strontium and caesium ions and tritiated water as diffusants. The results show that the diffusion of tritiated water is more rapid than that of other species, whilst the transport of strontium and caesium is hindered by sorption; particularly in materials containing blast furnace slag. The transport of gas in these materials has been found to be very sensitive to the degree of water saturation and is extremely low in fully saturated structural concretes. Cementitious backfills have, nevertheless, been identified that have appreciable gas transport even when almost water saturated. The consequences of the results for the performance of cementitious barriers are discussed
Nanouris, N.; Kalimeris, A.; Antonopoulou, E.; Rovithis-Livaniou, H.
2015-03-01
Context. The credibility of an eclipse timing variation (ETV) diagram analysis is investigated for various manifestations of the mass transfer and gravitational radiation processes in binary systems. The monotonicity of the period variations and the morphology of the respective ETV diagrams are thoroughly explored in both the direct impact and the accretion disk mode of mass transfer, accompanied by different types of mass and angular momentum losses (through a hot-spot emission from the gainer and via the L2/L3 points). Aims: Our primary objective concerns the traceability of each physical mechanism by means of an ETV diagram analysis. Also, possible critical mass ratio values are sought for those transfer modes that involve orbital angular momentum losses strong enough to dictate the secular period changes even when highly competitive mechanisms with the opposite direction act simultaneously. Methods: The dot{J-dot{P}} relation that governs the orbital evolution of a binary system is set to provide the exact solution for the period and the function expected to represent the subsequent eclipse timing variations. The angular momentum transport is parameterized through appropriate empirical relations, which are inferred from semi-analytical ballistic models. Then, we numerically determine the minimum temporal range over which a particular mechanism is rendered measurable, as well as the critical mass ratio values that signify monotonicity inversion in the period modulations. Results: Mass transfer rates comparable to or greater than 10-8 M⊙ yr-1 are measurable for typical noise levels of the ETV diagrams, regardless of whether the process is conservative. However, the presence of a transient disk around the more massive component defines a critical mass ratio (qcr ≈ 0.83) above which the period turns out to decrease when still in the conservative regime, rendering the measurability of the anticipated variations a much more complicated task. The effects of
Minimizing residues and strain in 2D materials transferred from PDMS
Jain, Achint; Bharadwaj, Palash; Heeg, Sebastian; Parzefall, Markus; Taniguchi, Takashi; Watanabe, Kenji; Novotny, Lukas
2018-06-01
Integrating layered two-dimensional (2D) materials into 3D heterostructures offers opportunities for novel material functionalities and applications in electronics and photonics. In order to build the highest quality heterostructures, it is crucial to preserve the cleanliness and morphology of 2D material surfaces that come in contact with polymers such as PDMS during transfer. Here we report that substantial residues and up to ∼0.22% compressive strain can be present in monolayer MoS2 transferred using PDMS. We show that a UV-ozone pre-cleaning of the PDMS surface before exfoliation significantly reduces organic residues on transferred MoS2 flakes. An additional 200 ◦C vacuum anneal after transfer efficiently removes interfacial bubbles and wrinkles as well as accumulated strain, thereby restoring the surface morphology of transferred flakes to their native state. Our recipe is important for building clean heterostructures of 2D materials and increasing the reproducibility and reliability of devices based on them.
The effect of the coating layer thickness on VOC extraction performance of a ceramic polymer composite membrane has been investigated. It was found, under experimental condiitons representing typical field operation, the overall mass transfer rates of feed components were control...
International Nuclear Information System (INIS)
Zyvoloski, G.A.; Robinson, B.A.; Dash, Z.V.; Trease, L.L.
1997-07-01
The mathematical models and numerical methods employed by the FEHM application, a finite-element heat- and mass-transfer computer code that can simulate nonisothermal multiphase multi-component flow in porous media, are described. The use of this code is applicable to natural-state studies of geothermal systems and groundwater flow. A primary use of the FEHM application will be to assist in the understanding of flow fields and mass transport in the saturated and unsaturated zones below the proposed Yucca Mountain nuclear waste repository in Nevada. The component models of FEHM are discussed. The first major component, Flow- and Energy-Transport Equations, deals with heat conduction; heat and mass transfer with pressure- and temperature-dependent properties, relative permeabilities and capillary pressures; isothermal air-water transport; and heat and mass transfer with noncondensible gas. The second component, Dual-Porosity and Double-Porosity/Double-Permeability Formulation, is designed for problems dominated by fracture flow. Another component, The Solute-Transport Models, includes both a reactive-transport model that simulates transport of multiple solutes with chemical reaction and a particle-tracking model. Finally, the component, Constitutive Relationships, deals with pressure- and temperature-dependent fluid/air/gas properties, relative permeabilities and capillary pressures, stress dependencies, and reactive and sorbing solutes. Each of these components is discussed in detail, including purpose, assumptions and limitations, derivation, applications, numerical method type, derivation of numerical model, location in the FEHM code flow, numerical stability and accuracy, and alternative approaches to modeling the component
Models for mass transfer effects in semi-fuel cells and for a silver-zinc battery
Venkatraman, Murali Sankar
Semi-Fuel Cells (SFCs) and Silver-Zinc batteries have been recognized as batteries for high power applications. For channel flow between two parallel plates, featured in SFCs, obstacles may take the form of ordered asymmetrical porous nets. The net controls the spacing between the two electrode plates. The effect of the inert insulating net and its geometry on the heat and mass transfer characteristics in such a system is presented. The governing equations for momentum, continuity, and energy are solved in a three-dimensional domain using a commercial computational fluid dynamics software for fully developed flow with constant temperature boundary conditions. The local Nusselt number is calculated from the resulting temperature distribution. This net also affects the limiting current distribution in an SFC operating at limiting current because it disrupts the parabolic laminar flow velocity distribution. Hence, the current density distribution is obtained from the Nusselt number distribution through a heat and mass transfer analogy. The location, spacing, and number of the longitudinal and transverse ribs of the net are shown to affect the local and average current density distributions and Nusselt numbers on each of the two electrode plates. The results show that transverse ribs have a greater effect and that the enhancements of the average current density of 250% can be obtained for a spacing of 0.94 x 10-3 m with greater than 16 transverse ribs. A silver-zinc battery shows similar mass transfer limitations while discharged at moderate to high discharge rates. A one-dimensional mathematical model consisting of a negative (zinc) electrode, separator, and positive (silver) electrode, has been developed to study the performance and thermal behavior of the silver-zinc cell during discharge. The physical phenomena described here are reaction kinetics, mass transfer and heat generation. The analysis includes finite matrix conductivities (thermal and electrical
Analysis of trace gases at ppb levels by proton transfer reaction mass spectrometry (PTR-MS)
International Nuclear Information System (INIS)
Lindinger, W.; Hansel, A.
1996-01-01
A proton transfer reaction mass spectrometry (PTR-MS) system has been developed which allows for on-line measurements of trace gas components with concentrations as low as 1 ppb. The method is based on reactions of H 3 O + ions, which perform non-dissociative proton transfer to most of the common organic trace constituents but do not react with any of the components present in clean air. Examples of medical information obtained by means of breath analysis, of environmental trace analysis, and examples in the field of food chemistry demonstrate the wide applicability of the method. (Authors)
Energy Technology Data Exchange (ETDEWEB)
Waesche, S.; Hempel, D.C. [Technische Univ. Braunschweig (Germany). Inst. fuer Bioverfahrenstechnik; Horn, H. [Fachhochschule Magdeburg (Germany). Hydro- und Abfallchemie
1999-07-01
Substance transfer in the boundary layer bulk/biofilm can be only inadequately described by conventional model concepts. In such cases where the surface structure of a biofilm adapts to given hydraulic conditions, the substance transfer phenomena need to be studied in depth. In addition, the entire biofilm structure is much influenced both by substrate conditions and by hydrodynamic conditions during growth. With a view to quantifying these factors, biofilms were cultured under various substrate and hydrodynamic conditions in tube reactors with a diameter of 2.6 cm. For characterizing the cultured biofilms, biofilm density and substrate turnover measured as maximum mass transfer density were determined in each test series. Biofilm density (dry biomass/biofilm volume) was determined by gravimetry. Maximum mass transfer densities in biofilm were established in batch experiments with excess substrate. By means of oxygen microelectrodes, oxygen profiles in the biofilm were measured directly in the reactor. These measurements concerned biofilms of thicknesses ranging from 400 to 2000 {mu}m, where the biofilms did not yet exhibit erosion. (orig.) [German] Der Stoffuebergang in der Grenzschicht Bulk/Biofilm ist mit herkoemmlichen Modellvorstellungen nur ungenuegend beschreibbar. Eine sich an die aktuellen hydraulischen Bedingungen anpassende Oberflaechenstruktur des Biofilms erfordert eine intensive Untersuchung der Stoffuebergangsphaenomene in derartigen Systemen. Darueber hinaus wird die gesamte Biofilmstruktur sowohl von den Substratbedingungen als auch von den hydrodynamischen Bedingungen waehrend des Wachstums stark beeinflusst. Um diese Faktoren quantifizieren zu koennen, wurden Biofilme bei verschiedenen Substrat- und hydrodynamischen Bedingungen in Rohrreaktoren mit einem Durchmesser von 2,6 cm kultiviert. Zur Charakterisierung der kultivierten Biofilme wurde die Biofilmdichte und der Substratumsatz, gemessen als maximale Massestromdichte, bei jeder Versuchsreihe
Directory of Open Access Journals (Sweden)
G. Revathi
2014-12-01
Full Text Available Non-similar solutions are found numerically to a system of coupled non-linear partial differential equations indicating, unsteady laminar water boundary layer flow over yawed cylinder using implicit finite difference scheme along with Quasi-linearization technique. The fluid properties such as viscosity and Prandtl number are considered as an inverse function of temperature. Unsteadiness is caused by upstream velocity in and directions and non-uniform mass transfer (suction/injection which is applied through slot on the surface of the geometry. The effect of yaw angle, variable fluid properties and non-uniform mass transfer on skin friction and heat transfer coefficients is analyzed. It is found that non-uniform slot suction and downstream movement of the slot cause the point of vanishing skin friction moves downstream, but non-uniform slot injection produces the opposite result of that corresponding to the suction case. When the yaw angle increases, both the skin friction coefficient in the – direction and the heat transfer coefficient decrease but the skin friction coefficient in the – direction increases for all times. The effect of the yaw angle is very little on the point of vanishing skin friction.
Energy Technology Data Exchange (ETDEWEB)
Azimi, Neda; Rahimi, Masoud, E-mail: masoudrahimi@yahoo.com
2017-01-15
Rotating magnetic field (RMF) was applied on a micromixer to break the laminar flow and induce chaotic flow to enhance mass transfer between two-immiscible organic and aqueous phases. The results of RMF were compared to those of static magnetic field (SMF). For this purpose, experiments were carried out in a T-micromixer at equal volumetric flow rates of organic and aqueous phases. Fe{sub 3}O{sub 4} nanoparticles were synthesized by co-precipitation technique and they were dissolved in organic phase. Results obtained from RMF and SMF were compared in terms of overall volumetric mass transfer coefficient (K{sub L}a) and extraction efficiency (E) at various Reynolds numbers. Generally, RMF showed higher effect in mass transfer characteristics enhancement compared with SMF. The influence of rotational speeds of magnets (ω) in RMF was investigated, and measurable enhancements of K{sub L}a and E were observed. In RMF, the effect of magnetic field induction (B) was investigated. The results reveal that at constant concentration of nanoparticles, by increasing of B, mass transfer characteristics will be enhanced. The effect of various nanoparticles concentrations (ϕ) within 0.002–0.01 (w/v) on K{sub L}a and E at maximum induction of RMF (B=76 mT) was evaluated. Maximum values of K{sub L}a (2.1±0.001) and E (0.884±0.001) were achieved for the layout of RMF (B=76 mT), ω=16 rad/s and MNPs concentration of 0.008–0.01 (w/v). - Highlights: • Magnetic nanoparticles used for mixing of two immiscible liquids in a micromixer. • Extraction efficiency of rotating magnetic field (RMF) is compared with static one. • In RMF, the effect of the angular speed on KLa and E enhancement is reported. • In RMF, at a selected magnet distance effect of nanoparticle concentration is reported.