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24 results on '"masstransfer"'

1. MATHEMATICAL AND COMPUTER MODELING OF CONTAMINANT MIGRATION TO FILTER TRAP IN TWO-DIMENSIONAL NONLINEAR CASE.

Author

Vlasyuk, Anatoliy, Kochan, Roman, Zhukovskyy, Viktor, and Zhukovska, Nataliia

Subjects
*COMPUTER simulation, *NONLINEAR analysis, *MATHEMATICAL models, *POLLUTANTS, *DARCY'S law
Abstract

The amelioration fund of Ukraine is 5.4 million hectares. Significant areas of these lands are used by special drainage-modular systems with vertical and horizontal drainage. Such drainage is a system of vertical or horizontal fluid drain storage, located in a parallel way. These systems can be used to inject micro- and nanoparticles of sorbent or as filter-traps for already used sorbent particles. Therefore, a fundamental understanding of the processes of mass transfer in a saturated porous medium in the presence of a filter-trap requires a detailed study of the new mathematical models. In this work, an appropriate mathematical model for the migration of contaminants in a saturated catalytic porous medium in a two-dimensional case is presented. Under the influence of the gradient pressure, there is a transfer of substances dissolved in water by a filtration flow. The filtration of the saline solution is carried out in accordance with the generalized Darcy law. Due to the transfer of substances at a certain speed under the influence of convective diffusion in a catalytic environment in the presence of trap filters the localization of the contaminant happens. Sorption nanoparticles that influence to the dynamics of the filtration process represents the catalytic medium. Finite-difference analogs of differential equations of a corresponding two-dimensional nonlinear boundary value problem are constructed and its numerical solution is obtained by finite difference method. A software package with the use of Orleans parallel calculations has been developed for performing numerical experiments. The interface of the software package is presented as a web application and end-user may use an only web browser for numerical experiments because all calculations are carried out in the Azure cloud service. The web application interface allows to manage the source data (diffusion coefficients, porosity, dispersion, boundary conditions, adsorption isotherms, etc.) that determine the hydrogeological conditions and possible effects of man-made factors; perform the necessary calculations, build comparative 2D/3D graphs and tables of values of concentrations, heads, filtration rates and diffusion coefficients. The influence of the catalytic medium on the process of soil layer refinement was established and various scenarios of vertical migration of contaminants were modeled due to the computer simulation and conducted numerical experiments. These results can be used to predict the refinement of soils from contaminant and predict their possible future use. [ABSTRACT FROM AUTHOR]

Published
2018
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2. Palladium supported on carbon nanotube modified nickel foam as a structured catalyst for polystyrene hydrogenation.

Author

Feng, Miao, Luo, Zhao-Hui, Chen, Rong-Qi, Yi, Shan, Lu, Hui, Cao, Gui-Ping, Lu, Chong, Feng, Shao-Yue, and Li, Chen-Yang

Subjects
*PALLADIUM, *CARBON nanotubes, *NICKEL, *HYDROGENATION, *FILTERS & filtration
Abstract

Graphical abstract Highlights • Structured Pd supported on carbon nanotube modified nickel foam (CNTs@NF) was employed in the hydrogenation of polystyrene. • Pd nanoparticles highly dispersed on CNTs@NF surface displayed an excellent hydrogenation degree of PS. • CNTs@NF formed an inverse structure of traditional porous support and provided open accessible surface. • Enhanced mass transfer and abundant effective active sites contributed to the high performance of Pd/CNTs@NF. • Pd/CNTs@NF showed similar activity as slurry CNTs supported catalyst (Pd/CNTs) with the merit of avoiding filtration. Abstract A structured support of carbon nanotubes modified nickel foam (CNTs@NF) was synthesized through a facile method of chemical vapor deposition. The entangled CNTs layer with open pores and the dense carbon layer beneath covered around the skeleton of nickel foam establishes a hybrid hierarchical structure with large effective surface area which dramatically promotes the internal diffusion of large polystyrene (PS) coils. Palladium was chosen as the catalyst for PS hydrogenation and deposited on the CNTs@NF support in the form of nanoparticles. Characterization analysis including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermo gravimetric analysis (TGA), Raman spectrum and N 2 physisorption were conducted to investigate the morphology and structure of the resulting Pd supported on CNTs@NF catalysts (Pd/CNTs@NF). The macroscopic structured Pd/CNTs@NF catalyst was applied to PS hydrogenation and displayed a quite excellent hydrogenation activity with a final hydrogenation degree (HD) of 73.6%, almost 8 times higher than nickel foam supported Pd catalyst (Pd/NF) and remarkably similar to powdered CNTs supported Pd catalyst (Pd/CNTs) under the identical condition. Moreover, the turn-over-frequency (TOF) of Pd/CNTs@NF (0.041 s−1) was also comparable to Pd/CNTs (0.056 s−1), which confirmed a similar intrinsic catalytic activity of Pd on both supports. Inspiringly, the performance of Pd/CNTs@NF catalyst was comparable to powdered Pd/CNTs catalyst with the merit of eliminating filtration operation. It has revealed the structured Pd/CNTs@NF catalyst with outstanding recyclability could be an attractive alternative to the powdered Pd/CNTs catalyst for heterogeneously catalyzed polymers hydrogenation reactions. [ABSTRACT FROM AUTHOR]

Published
2019
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3. Hall effect on MHD mixed convection flow of a viscoelastic fluid past an infinite vertical porous plate with mass transfer and radiation

Author

Chaudhary R.C. and Jain Preeti

Subjects
hall effect, viscoelastic fluid, radiative transfer, masstransfer, mixed-convection, Mechanics of engineering. Applied mechanics, TA349-359
Abstract

An unsteady hydro-magnetic flow of a viscoelastic fluid from a radiative vertical porous plate has been studied with mass transfer, taking the effect of Hall currents into account. The resulting problem has been solved analytically and the closed form solutions are obtained for velocity, temperature and concentration distributions as well as for the shearing stress, rate of heat and mass transfer at the wall. The influence of the various parameters like Hall parameter, magnetic parameter, viscoelastic parameter, frequency parameter etc. on the flow field is examined with the help of figures and tables.

Published
2006
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4. Інтенсифікація багатофазних реакцій в мікрореакторах

Author

Reschetilowski, W.

Subjects
масообмін, наночастицы, мікроструктурний реактор, мікроканал, каталіз, многофазная система, катализ, массообмен, микроканал, multiphase system, наночастинки, microstructured reactor, kinetics, багатофазна система, microchannel, nanoparticles, кінетика, masstransfer, микроструктурный реактор, кинетика
Abstract

В даній роботі подається короткий огляд сучасного розвитку і досягнень мікрореакційної техніки на прикладі багатофазних систем, що розрізняються за своєю природою і проводяться в мікроструктурних реакторах різного типу: каталіз на межі розділу фаз, біокаталіз і синтез наночастинок. Особливу увагу приділяється аспектам інтенсифікації багатофазних процесів в мікроструктурних реакторах, так як саме це робить мікрореакційну техніку привабливою для хімічної промисловості. In this work the state of the art as well as the recent developments in microreactor technology are reviewed basing on different types of multiphase reaction systems: phase transfer catalysis, biocatalysis and synthesis of nanoparticles. The intensification of multiphase processes in microstructured reactors comparing to traditional approaches, which makes them of great interest for the chemical industry, is especially discussed. В данной работе приводится краткий обзор современного развития и достижений микрореакционной техники на примере многофазных систем, различающихся по своей природе и проводимых в микроструктурних реакторах разного типа: катализ на границе раздела фаз, биокатализ и синтез наночастиц. Особое внимание уделяется аспектам интенсификации многофазных процессов в микрореакторах, так как именно это делает микрореакционную технику привлекательной для химической промышленности.

Published
2021

5. PROPERTIES OF NANOSTRUCTURED COATINGS Ti-Hf-N (Fe).

Author

Beresnev, V. M., Kolesnikov, D. A., Kaverin, M. V., Melnik, S. S., and Postolnyi, B. O.

Subjects
THIN films, COATING processes, SURFACES (Technology), PROPERTIES of matter, INTERMEDIATES (Chemistry), SOLUTION (Chemistry)
Abstract

Superhard nanostructured coatings which consist of Ti-Hf-N (Fe) were obtained. The formation of local zones of (Ti, Hf) N; FeN and Hf were detected with μ - PIXE (microbeam ions). It was revealed that the synthesized coatings have a hardness of 47,78 ± 1.2 GPa, and formed from nanograins with sizes ranging from 4.8 to 10.6 nm, which enveloped the smaller entities of other phases (Ti, Fe) N and FeN. [ABSTRACT FROM AUTHOR]

Published
2012

6. Review Article: The Existing Models for Simulation of Pulsed and Reciprocating Columns—How Well do they Work in the Real World?

Author

Grinbaum, B.

Subjects
*PLATE towers, *MODELING (Sculpture), *SIMULATION methods & models, *MASS transfer, *HYDRODYNAMICS, *FLUID dynamics, *SOLVENT extraction
Abstract

The purpose of this article is to review the state of art of the existing approaches to the design and analysis of pulsed and reciprocating columns, compare the merits of the theoretical models vs. the experimental “black box” method, and try to recommend a way to obtain a fruitful cooperation between researchers using different approaches. There are three main theoretical approaches: models based on the correlation of single parameters (holdup, drop size, mass‐transfer coefficient etc.), drop population balances, and computational fluid dynamics (CFD). At present, the design of new columns is based only on experimental data from piloting, sometimes with the assistance of mass‐balance simulators. And the experimental “black box approach” has proven to be efficient and quick, especially since at present no company considers the erection of a new column without some experimental verification. In the long term powerful models may enable the solution of many solvent extraction problems with reliability that does not require experimental verification. In order to be widely useful, these models have to be transformed into user‐friendly simulators that require only easily available data as input. To achieve this, there must be close cooperation between the academic world and industry. Otherwise, they will simply remain academic exercises. And at the present state of knowledge, pilot‐plant testing remains an almost inevitable preliminary step to a full‐scale column design. [ABSTRACT FROM AUTHOR]

Published
2006
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7. Butyrate production from carbon monoxide by Butyribacterium methylotrophicum.

Author

Worden, R., Grethlein, A., Zeikus, J., and Datta, R.

Abstract

Carbon monoxide is produced in high concentrations by gasification of coal or biomass, and is a potentially inexpensive feedstock for biological processes. A number of anaerobic microorganisms metabolize carbon monoxide, with acetate, hydrogen, or methane being the primary reduced products. The CO strain of Butyribacterium methylotrophicum was previously shown to grow on carbon monoxide as the sole carbon and energy source, with acetate being the primary product. This paper demonstrates that by modifying culture conditions, the carbon and electron flow of B. methylotrophicum can be manipulated to yield butyrate as the major product. A butyrate concentration of 6 g/L was obtained in batch culture with continuous addition of 100% carbon monoxide. The significance of this fermentation for fuels and chemicals production from carbon monoxide is discussed. [ABSTRACT FROM AUTHOR]

Published
1989
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8. Osmotic dehydration of green mango samples (Mangifera indica L., Filipino var.) in ternary solutions

Author

Adriana del Rosario Micanquer-Carlosama, Alfredo Ayala-Aponte, and Liliana Serna-Cock

Subjects
Chromatography, Coacervate, Water activity, Chemistry, Capsule, sucrose, TP368-456, Double emulsion, Applied Microbiology and Biotechnology, Controlled release, Nanocapsules, Food processing and manufacture, kinetics, NaCl, Masstransfer, Mass transfer, Solubility, HD9665-9675, Pharmacology, Toxicology and Pharmaceutics (miscellaneous), Flavor, Pharmaceutical industry, Food Science
Abstract

Background: in Colombian the consumption of fresh green mango (also known as mango “biche”) is quite popular, and is consumed with lemon juice, salt, and honey. However, its high humidity content and high water activity makes of mango a highly perishable fruit, thus requiring processing alternatives. Osmotic dehydration (OD) is an interesting alternative for the conservation of mango. In OD, binary solutions (Solute + water) and ternary solutions (2 Solutes + water), have been traditionally used, however, more water removal can be achieved using ternary solutions, which leads to the improved organoleptic properties of dehydrated products Objetives: to evaluate the kinetic water loss (WL), solutes gain (SG), weight reduction (WR), water activity (a w ), and volume (Shrinking Coefficient, SC)) in green mango (Mangifera indica L. Filipino variety) osmotically dehydrated (OD). Additionally, to calculate water and solutes diffusivity (D ef ) for each treatment. Methods: green mango samples, with maturity scale zero, were used. Ternary solutions of sucrose at 40% and NaCl at 3, 6 and 9% were used for OD. The binary solution of sucrose with water as control treatment, was used. In the osmotic process samples were taken out at different times of OD (15, 30, 60, 90, 180, 240, and 300 min). Results: the findings show that at a higher concentration of NaCl, the dehydration kinetics was more rapid, a w and SC were smaller and, water and solutes D ef were higher. The samples dehydrated with the greatest solutes concentration (40 - 9%) reached the highest WL, SG, and WR with 89.52, 13.10, and 46.68%, respectively. Coefficients D efw and D efs showed a magnitude order of 10-10 m2/s, which is within the interval of dehydrated foods. Conclusions: this research showed that binary (sucrose + water) and ternary (NaCl + sucrose + water) solutions, are suitable for dehydrating green mango, however, the ternary solutions were more effective.

Published
2018

9. OSMOTIC DEHYDRATION OF GREEN MANGO SAMPLES (Mangifera indica L., Filipino Var.) IN TERNARY SOLUTIONS

Author

Ayala-Aponte, Alfredo A, Molina-Cortés, Andrea, and Serna-Cock, Liliana

Subjects
sacarosa, cinética, NaCl, Masstransfer, sucrose, transferencia, Masa, cloruro de sodio, kinetics
Abstract

Background: in Colombian the consumption of fresh green mango (also known as mango “biche”) is quite popular, and is consumed with lemon juice, salt, and honey. However, its high humidity content and high water activity makes of mango a highly perishable fruit, thus requiring processing alternatives. Osmotic dehydration (OD) is an interesting alternative for the conservation of mango. In OD, binary solutions (Solute + water) and ternary solutions (2 Solutes + water), have been traditionally used, however, more water removal can be achieved using ternary solutions, which leads to the improved organoleptic properties of dehydrated products Objetives: to evaluate the kinetic water loss (WL), solutes gain (SG), weight reduction (WR), water activity (a w ), and volume (Shrinking Coefficient, SC)) in green mango (Mangifera indica L. Filipino variety) osmotically dehydrated (OD). Additionally, to calculate water and solutes diffusivity (D ef ) for each treatment. Methods: green mango samples, with maturity scale zero, were used. Ternary solutions of sucrose at 40% and NaCl at 3, 6 and 9% were used for OD. The binary solution of sucrose with water as control treatment, was used. In the osmotic process samples were taken out at different times of OD (15, 30, 60, 90, 180, 240, and 300 min). Results: the findings show that at a higher concentration of NaCl, the dehydration kinetics was more rapid, a w and SC were smaller and, water and solutes D ef were higher. The samples dehydrated with the greatest solutes concentration (40 - 9%) reached the highest WL, SG, and WR with 89.52, 13.10, and 46.68%, respectively. Coefficients D efw and D efs showed a magnitude order of 10-10 m2/s, which is within the interval of dehydrated foods. Conclusions: this research showed that binary (sucrose + water) and ternary (NaCl + sucrose + water) solutions, are suitable for dehydrating green mango, however, the ternary solutions were more effective. RESUMEN Antecedentes: en Colombia el consumo de mango verde fresco (también conocido como mango “biche”) es popular, y se consume con zumo de limón, sal y miel. Sin embargo, su alto contenido de humedad y alta actividad de agua hace que el mango sea un fruto altamente perecedero, por lo que requiere alternativas de procesamiento. La deshidratación osmótica (OD) es una interesante alternative para la conservación de mango. En OD se utilizan tradicionalmente soluciones binarias (solute + agua) y soluciones ternarias (2 solutos + agua), sin embargo, puede removerse mayor cantidad de agua utilizando soluciones ternarias, las cuales permiten mejorar las propiedades organolépticas de productos deshidratados. Objetivos: evaluar las cinéticas de pérdida de agua (WL), ganancia de solutos (SG), reducción de peso (WR), actividad de agua (a w ) y volumen (coeficiente de encogimiento, SC) en muestras de mango verde (Mangifera indica L. Filipino variety) deshidratadas osmóticamente (OD). Adicionalmente, calcular la difusividad (D ef ) del agua y de solutos, en los distintos tratamientos. Métodos: se usaron mangos verdes con escala de madurez cero. En la OD se usaron soluciones ternarias compuestas por sacarosa (40%) y NaCl al 3, 6 y 9%. Como tratamiento control se usó una solución binaria de sacarosa más agua. En el proceso osmótico las muestras fueron tomadas a diferentes tiempos de OD (15, 30, 60, 90, 180, 240, and 300 min). Resultados: Los resultados mostraron que al incrementar la concentración de NaCl, las WL fueron más rápidas, la a w y el SC fueron menores y las D ef de agua y solutos mayores. Las muestras deshidratadas con la máxima concentración de solutos (40-9%), alcanzaron las mayores WL, SG y WR con valores de 59.82, 13.10 y 46.68%, respectivamente. Los coeficientes D efw and D efs mostraron orden de magnitude de 10-10 m2/s, valor que se encuentra en el intervalo para alimentos deshidratados. Conclusiones: esta investigación mostró que soluciones binarias (sacarosa + agua) y ternarias (NaCl + sacarosa + agua) son adecuadas para deshidratar mango verde, sin embargo, las soluciones ternarias fueron más efectivas.

Published
2018

10. Modification of the Constructional Materials with the Intensive Charged Particle Beams and Plasma Flows

Author

Leyvi, A.Ya., Talala, K.A., Krasnikov, V.S., and Yalovets, A.P.

Subjects
microrelief modification, diffusion, ion beams, intensive plasma flows, термокапиллярная конвекция, дислокации, диффузия, электронные пучки, 532 [УДК 538.9], ионные пучки, electron beams, массоперенос, plasticity, thermocapillary convection, модификация микрорельефа, masstransfer, интенсивные плазменные потоки, пластичность, dislocations
Abstract

Лейви Артем Ячеславович, кандидат физико-математических наук, доцент кафедры «Общая и экспериментальная физика», Южно-Уральский государственный университет, г. Челябинск, leyvy@mail.ru. Талала Ксения Анатольевна, кандидат физико-математических наук, научный сотрудник управления научной и инновационной деятельности, Южно-Уральский государственный университет, г. Челябинск, ktalala@yandex.ru. Красников Василий Сергеевич, кандидат физико-математических наук, научный сотрудник управления научной и инновационной деятельности, Южно-Уральский государственный университет, г. Челябинск, va_ja@mail.ru. Яловец Александр Павлович, доктор физико-математических наук, профессор кафедры «Общая и теоретическая физика», Южно-Уральский государственный университет, г. Челябинск, yalovets.alex@rambler.ru. A.Ya. Leyvi, leyvy@mail.ru, K.A. Talala, ktalala@yandex.ru, V.S. Krasnikov, va_ja@mail.ru, A.P. Yalovets, yalovets.alex@rambler.ru South Ural State University, Chelyabinsk, Russian Federation Приведен анализ современного состояния экспериментальных и теоретических исследований по модификации конструкционных материалов интенсивными потоками заряженных частиц и плазмы с плотностями мощности 0,1–1000 МВт/см2. Показано, что плотность вложенной в мишень энергии и длительность облучения являются главными факторами, определяющими спектр протекающих в веществе процессов. Возможна реализация двух режимов облучения: докритического и закритического. В докритическом режиме облучения вещество мишени остается в твердом состоянии или же переходит в жидкое, в закритическом режиме происходит формирование плазменного факела и его последующий разлет со скоростью более 103 м/с. Переход от докритического к закритическому режиму носит пороговый характер. Обсуждаются механизмы формирования полей механических напряжений в облучаемой мишени, которые представляют собой распространяющуюся со скоростью звука ударную волну, а также локализованные вблизи облучаемой поверхности напряжения, обусловленные неоднородным по объему полем температур. Описана природа явлений сглаживания микрорельефа облучаемой поверхности и образования на ней микрократеров. Показано, что проявление того или иного явления определяется режимом облучения. Проведен анализ явления массопереноса за счет процессов диффузии, термокапиллярной конвекции и развития неустойчивости Рихтмайера–Мешкова в зависимости от режима облучения. Облучение твердых тел приводит к увеличению плотности дислокаций, в основ- ном, за счет сдвиговой составляющей локализованных напряжений. Уменьшение дли- тельности облучения приводит к более высоким скоростям деформаций, что вызывает более эффективную наработку дислокаций из-за более высоких значений сдвиговых напряжений. The irradiation modes with the inherent physical processes and the role of different mechanisms in formation of the properties of treated materials are surveyed. The irradiation can be divided onto two modes: subcritical and supercritical. In the subcritical irradiation mode a target material remains in the solid state or melts. In the supercritical regime the formation of plasma torch and its subsequent expansion at a rate of more than 103 m/s are observed. The transition from subcritical to supercritical mode has a threshold character. The mechanisms of mechanical stresses formation under irradiation are discussed, these stresses are the shock wave propagating with a sound velocity and the localized near the irradiated surface stresses arising due to the nonhomogeneous space distribution of the temperature in target material. The reasons of target surface smoothing and of crater formation are given. It is shown that the manifestation of one or another phenomenon of irradiation is determined by its mode. The analysis of mass transfer occurring due to diffusion, thermocapillary convection or development of Richtmyer-Meshkov instability is carried out in accordance with the irradiation mode. The irradiation of the solids leads to the deformation hardening mainly at the expense of shear component of the localized stresses. The decrease of the irradiation duration provokes the high strain rate and the high level of shear stresses that both provide more effective generation of dislocations. Работа выполнена при финансовой поддержке Министерства образования и науки РФ (научно-исследовательская работа ФГБОУ ВПО «ЮУрГУ» (НИУ), проводимой в рамках государственного задания № 1030 (№ 2014105-ГЗ).

Published
2016

11. Chemometric approach to the analysis ofosmotic dehydration of silver crucian carp(Carassius gibelio)

Author

Lončar, Biljana, Lević, Ljubinko, Džinić, Natalija, Pavkov, Ivan, and Pezo, Lato

Subjects
Hemometrija, melasa šećerne repe, silver crucian carp, srebrni karaš, masstransfer, Chemometrics, osmotic dehydration, sugar beet molasses, prenos mase, osmotska dehidratacija
Abstract

Hemometrijskim metodama (deskriptivna statistika, analiza glavnih komponenti, veštačke neuronske mreže i fazi optimizacija) analizirani su rezultati procesa osmotske dehidratacije mesa srebrnog karaša, sa ciljem unapređenja efikasnosti osmotskog tretmana i pronalaženja optimalnih tehnoloških parametara. Osmotski tretman se odvijao u tri osmotska rastvora (vodeni rastvor natrijum hlorida i saharoze, kombinacija vodenog rastvora natrijum hlorida i saharoze i melase i melasa šećerne repe) različitih koncentracija, na četiri temperature (10°C, 20°C, 35°C i 50°C) i pri tri vremena procesa (1, 3 i 5h). Posmatrani su sledeći odzivi sistema: gubitak vode, priraštaj suve materije, povećanje sadržaja suve materije, sniženje aktivnosti vode i promena sadržaja minerala (Na, K, Ca i Mg). Karakterizacijom osmotski dehidriranog ribljeg polupoizvoda, pojašnjeni su efekti osmotskog tretmana i inovatinog osmotskog rastvora na senzorne osobine, hemijski i mikrobiološki profil tretiranog mesa ribe. Rezultati ispitivanja pokazuju da se primenom procesa osmotske dehidratacije povećava gubitak vode, priraštaj suve materije i sadržaj suve materije u svim uzorcima mesa srebrnog karaša. Za sva tri osmotska rastvora, najveće vrednosti dobijene su nakon 5 časova, pri najvišim temperaturama i u najvećim koncentracijama rastvora. Povećavanjem temperature procesa, koncentracije rastvora i vremena trajanja procesa, povećan je sadržaj posmatranih minerala u tretiranom mesu ribe. Rezultati ANOVA testa pokazali su da na vrednosti posmatranih odziva statistički značajno utiču sva tri parametra: vreme, temperatura i koncentracija. PCA analizom procesa utvrđeno je da su pri izračunavanju prve glavne komponente najveći uticaj imale vrednosti svih odziva osim aw vrednosti, dok je ona najviše uticala na proračun druge glavne komponente. Iako su modeli veštačkih neuronskih mreža kompleksniji od modela polinoma drugog reda, mreže su pokazale bolji učinak usled visoke nelinearnosti razvijenih sistema. Primenom fazi optimizacije postignute optimalne vrednosti procesnih parametara za vodeni rastvor natrijum hlorida i saharoze su bile na nižim temperaturama i nižim koncentracijama rastvora, dok su za rastvore sa melasom šećerne repe optimalne vrednosti na maksimumima posmatranih opsega temperature i koncentracije rastvora. Procesom osmotske dehidratacije smanjen je inicijalni broj bakterija u mesu srebrnog karaša. Hemijskim i senzorskim analizama utvrđeno je da je melasa šećerne repe zbog svog kompleksnog nutritivnog sastava povoljnije je delovala na promenu hemijskog sastava i senzorne osobine uzoraka u odnosu na druga dva rastvora. Chemometric methods (descriptive statistics, principal components analysis, artificial neural networks and fuzzy optimization) were used to analyze the results of osmotic dehydration of silver crucian carp, with the aim of improving the efficiency of the osmotic treatment and finding the optimal technological parameters. The osmotic treatment was carried out in three osmotic solution (aqueous sodium chloride and sucrose solution, sugar beet molasses and the combination of these two solutions) of varying concentrations, at four temperatures (10°C, 20°C, 35°C and 50°C) and at three processing times (1, 3 and 5 h). The observed system responses were: water loss, solid gain, increase in dry matter content, reduction of water activity and changes in mineral content (Na, K, Ca and Mg). The characterization of dehydrated fish, explained the effects of osmotic treatment on its sensory properties, chemical and microbiological profile. Results have shown that the application of osmotic dehydration increases water loss, solid gain and dry matter content in all samples of fish meat. For all three osmotic solution, the highest values were obtained after 5h, at the highest temperatures and in the highest concentration of the solution. By increasing the process temperature, concentration and time, increased the mineral content in the fish meat. The results of the ANOVA test have shown that the values of the observed responses significantly affect all three parameters: time, temperature and concentration. PCA analysis process has found that on calculation of the first principal component all response values except aw value had the greatest impact, while aw value had the most influence on the calculation of the other major component. Although models of artificial neural network models are more complex than second order polynomial, the network showed better performance due to the high nonlinearity of the developed system. Application of fuzzy optimization obtained optimal values of the process parameters for aqueous solution of sodium chloride and sucrose were at lower temperatures and lower concentrations of the solution, while the solutions with molasses optimal values of the maxima observed ranges of temperature and solution concentration. The process of osmotic dehydration has reduced the initial number of bacteria in meat silver carp. Chemical and sensory analyzes have shown that the sugar beet molasses due to its complex nutritional composition has a better effect on changing the chemical composition and sensory characteristics of the samples.

Published
2015

12. Hall effect on MHD mixed convection flow of a viscoelastic fluid past an infinite vertical porous plate with mass transfer and radiation

Author

Preeti Jain and R. C. Chaudhary

Subjects
Physics, Applied Mathematics, Mechanical Engineering, Flow (psychology), mixed-convection, Computational Mechanics, Mechanics, Viscoelasticity, Physics::Fluid Dynamics, hall effect, Classical mechanics, radiative transfer, Hall effect, Combined forced and natural convection, Mass transfer, viscoelastic fluid, Radiative transfer, Shear stress, masstransfer, Magnetohydrodynamics, lcsh:Mechanics of engineering. Applied mechanics, lcsh:TA349-359
Abstract

An unsteady hydro-magnetic flow of a viscoelastic fluid from a radiative vertical porous plate has been studied with mass transfer, taking the effect of Hall currents into account. The resulting problem has been solved analytically and the closed form solutions are obtained for velocity, temperature and concentration distributions as well as for the shearing stress, rate of heat and mass transfer at the wall. The influence of the various parameters like Hall parameter, magnetic parameter, viscoelastic parameter, frequency parameter etc. on the flow field is examined with the help of figures and tables.

Published
2006
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13. Hemometrijski pristup analizi osmotske dehidratacije srebrnog karaša (Carassius gibelio)

Author

Lević, Ljubinko, Džinić, Natalija, Pavkov, Ivan, Pezo, Lato, Lončar, Biljana, Lević, Ljubinko, Džinić, Natalija, Pavkov, Ivan, Pezo, Lato, and Lončar, Biljana

Abstract

Hemometrijskim metodama (deskriptivna statistika, analiza glavnih komponenti, veštačke neuronske mreže i fazi optimizacija) analizirani su rezultati procesa osmotske dehidratacije mesa srebrnog karaša, sa ciljem unapređenja efikasnosti osmotskog tretmana i pronalaženja optimalnih tehnoloških parametara. Osmotski tretman se odvijao u tri osmotska rastvora (vodeni rastvor natrijum hlorida i saharoze, kombinacija vodenog rastvora natrijum hlorida i saharoze i melase i melasa šećerne repe) različitih koncentracija, na četiri temperature (10°C, 20°C, 35°C i 50°C) i pri tri vremena procesa (1, 3 i 5h). Posmatrani su sledeći odzivi sistema: gubitak vode, priraštaj suve materije, povećanje sadržaja suve materije, sniženje aktivnosti vode i promena sadržaja minerala (Na, K, Ca i Mg). Karakterizacijom osmotski dehidriranog ribljeg polupoizvoda, pojašnjeni su efekti osmotskog tretmana i inovatinog osmotskog rastvora na senzorne osobine, hemijski i mikrobiološki profil tretiranog mesa ribe. Rezultati ispitivanja pokazuju da se primenom procesa osmotske dehidratacije povećava gubitak vode, priraštaj suve materije i sadržaj suve materije u svim uzorcima mesa srebrnog karaša. Za sva tri osmotska rastvora, najveće vrednosti dobijene su nakon 5 časova, pri najvišim temperaturama i u najvećim koncentracijama rastvora. Povećavanjem temperature procesa, koncentracije rastvora i vremena trajanja procesa, povećan je sadržaj posmatranih minerala u tretiranom mesu ribe. Rezultati ANOVA testa pokazali su da na vrednosti posmatranih odziva statistički značajno utiču sva tri parametra: vreme, temperatura i koncentracija. PCA analizom procesa utvrđeno je da su pri izračunavanju prve glavne komponente najveći uticaj imale vrednosti svih odziva osim aw vrednosti, dok je ona najviše uticala na proračun druge glavne komponente. Iako su modeli veštačkih neuronskih mreža kompleksniji od modela polinoma drugog reda, mreže su pokazale bolji učinak usled visoke nelinearnosti razvijenih sistema. Primeno, Chemometric methods (descriptive statistics, principal components analysis, artificial neural networks and fuzzy optimization) were used to analyze the results of osmotic dehydration of silver crucian carp, with the aim of improving the efficiency of the osmotic treatment and finding the optimal technological parameters. The osmotic treatment was carried out in three osmotic solution (aqueous sodium chloride and sucrose solution, sugar beet molasses and the combination of these two solutions) of varying concentrations, at four temperatures (10°C, 20°C, 35°C and 50°C) and at three processing times (1, 3 and 5 h). The observed system responses were: water loss, solid gain, increase in dry matter content, reduction of water activity and changes in mineral content (Na, K, Ca and Mg). The characterization of dehydrated fish, explained the effects of osmotic treatment on its sensory properties, chemical and microbiological profile. Results have shown that the application of osmotic dehydration increases water loss, solid gain and dry matter content in all samples of fish meat. For all three osmotic solution, the highest values were obtained after 5h, at the highest temperatures and in the highest concentration of the solution. By increasing the process temperature, concentration and time, increased the mineral content in the fish meat. The results of the ANOVA test have shown that the values of the observed responses significantly affect all three parameters: time, temperature and concentration. PCA analysis process has found that on calculation of the first principal component all response values except aw value had the greatest impact, while aw value had the most influence on the calculation of the other major component. Although models of artificial neural network models are more complex than second order polynomial, the network showed better performance due to the high nonlinearity of the developed system. Application of fuzzy optimization obtained optimal values of t

Published
2015

14. OSMOTIC DEHYDRATION OF GREEN MANGO SAMPLES (Mangifera indica L., Filipino Var.) IN TERNARY SOLUTIONS

Author

Alfredo A Ayala-Aponte, Andrea Molina-Cortés, and Liliana Serna-Cock

Subjects
Masstransfer, sucrose, NaCl, kinetics., Food processing and manufacture, TP368-456, Pharmaceutical industry, HD9665-9675
Abstract

ABSTRACT Background: in Colombian the consumption of fresh green mango (also known as mango “biche”) is quite popular, and is consumed with lemon juice, salt, and honey. However, its high humidity content and high water activity makes of mango a highly perishable fruit, thus requiring processing alternatives. Osmotic dehydration (OD) is an interesting alternative for the conservation of mango. In OD, binary solutions (Solute + water) and ternary solutions (2 Solutes + water), have been traditionally used, however, more water removal can be achieved using ternary solutions, which leads to the improved organoleptic properties of dehydrated products Objetives: to evaluate the kinetic water loss (WL), solutes gain (SG), weight reduction (WR), water activity (a w ), and volume (Shrinking Coefficient, SC)) in green mango (Mangifera indica L. Filipino variety) osmotically dehydrated (OD). Additionally, to calculate water and solutes diffusivity (D ef ) for each treatment. Methods: green mango samples, with maturity scale zero, were used. Ternary solutions of sucrose at 40% and NaCl at 3, 6 and 9% were used for OD. The binary solution of sucrose with water as control treatment, was used. In the osmotic process samples were taken out at different times of OD (15, 30, 60, 90, 180, 240, and 300 min). Results: the findings show that at a higher concentration of NaCl, the dehydration kinetics was more rapid, a w and SC were smaller and, water and solutes D ef were higher. The samples dehydrated with the greatest solutes concentration (40 - 9%) reached the highest WL, SG, and WR with 89.52, 13.10, and 46.68%, respectively. Coefficients D efw and D efs showed a magnitude order of 10-10 m2/s, which is within the interval of dehydrated foods. Conclusions: this research showed that binary (sucrose + water) and ternary (NaCl + sucrose + water) solutions, are suitable for dehydrating green mango, however, the ternary solutions were more effective.

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15. Development of hydrodynamic mode of operation of the foam device on tubular lattices with the foam stabilizer

Subjects
columnar vehicles, колонные аппараты, foamy layer, tubular grates, массопередача, трубчатые решетки, пенный слой, masstransfer
Abstract

В статье рассмотрены вопросы, связанные с конструктивными особенностями колонных аппаратов, которые позволяют увеличить высоту пенного слоя на трубчатых решетках аппаратов, при этом, не увеличивая скорость газового потока. Разработанный нами контактный элемент имеет хорошие показатели для широкого диапазона нагрузок по жидкости и газу. Описанные в статье методы расчета полностью подтверждают экспериментальные исследования и хорошо коррелируют с ранее проведенными исследованиями. Questions, related to the structural features of columnar vehicles which allow to increase the height of foamy layer on the tubular grates of vehicles, are considered in the article, here, not increasing speed of gas stream. Developed by us a contact element has good indexes for the wide range of loadings on a liquid and gas. The methods of calculation described in the article fully confirm experimental researches and well correlate with the before conducted researches.

Published
2009

16. This title is unavailable for guests, please login to see more information.

Abstract

Questions, related to the structural features of columnar vehicles which allow to increase the height of foamy layer on the tubular grates of vehicles, are considered in the article, here, not increasing speed of gas stream. Developed by us a contact element has good indexes for the wide range of loadings on a liquid and gas. The methods of calculation described in the article fully confirm experimental researches and well correlate with the before conducted researches

Published
2009

17. Research of hydrodynamics and masstransfer on the valve tray with spherical valve

Author

Vaskin, Roman Anatoliiovych

Subjects
гідродинаміка, hydrodynamics, массопередача, гидродинамика, masstransfer, valve, клапан
Abstract

Дисертація присвячена вивченню гідродинаміки і масопередачі на клапанній тарілці зі сферичними клапанами, призначеної для процесів ректифікації та абсорбції. Вивчено гідродинамічні особливості роботи тарілок, виявлено три режими тарілок, визначені гідродинамічні показники роботи тарілок: гідравлічний опір сухої і зрошуваної тарілки, міжтарільчасте винесення рідини. На підставі запропонованої схеми дії сил на клапан масообмінної тарілки розроблена методика визначення мінімальної і максимальної швидкості в отворах тарілки в режимі саморегулювання. Отримано залежності для визначення коефіцієнтів масовіддачі в газовій і рідкій фазах. Розроблено інженерну методику розрахунку клапанної тарілки зі сферичними клапанами. Запропонована конструкція клапанної тарілки була впроваджена при модернізації ректифікаційної установки стабілізації нафти на Качанівському ВКПН. Диссертация посвящена изучению гидродинамики и массопередачи на клапанной тарелке со сферическими клапанами, предназначенной для процессов ректификации и абсорбции. Предложена и защищена патентом Украины конструкция клапанной тарелки со сферическими клапанами, позволяющая за счет дробления газовых струй на зубчатых прорезях газовых патрубков калапанов увеличить поверхность контакта взаимодействующих фаз. Детальные исследования гидродинамики и массообмена, проведенные соискателем, позволили выполнить инженерные расчеты конструкции клапанной тарелки со сферическими клапанами, испытать ее работу в производственных условиях и сделать вывод о целесообразности внедрения ее в производство. Изучены гидродинамические особенности работы тарелок, выявлены три режима тарелок, определены гидродинамические показатели работы тарелок: гидравлическое сопротивление сухой и орошаемой тарелки, межтарельчатый унос жидкости. Показано, что за счет направленного выхода газовых струй из-под клапанов снижается скорость выхода газа на поверхность жидкости, что в свою очередь уменьшает унос жидкости на вышележащую тарелку и позволяет сократить расстояние между тарелками. На основании предложенной схемы действия сил на клапан масообменной тарелки разработана методика определения минимальной и максимальной скорости в отверстиях тарелки в режиме саморегулирования. Исследована кинетика массообмена. Получены зависимости для определения коэффициентов масоотдачи в газовой и жидкой фазах, в зависимости от режимных и конструктивных параметров тарелки. Конструкция разработанной клапанной тарелки показала высокую эффективность при проведении лабораторных и промышленных испытаний, по сравнению с широко применяемыми клапанными тарелками. Разработана инженерная методика расчета клапанной тарелки со сферическими клапанами. Предложенная конструкция клапанной тарелки была внедрена при модернизации ректификационной установки стабилизации нефти на Качановском УКПН. The dissertation is devoted to studying of hydrodynamics and masstransfer on valve tray with the spherical valves, intended for rectification and absorption. Hydrodynamics features of trays work are investigated, three modes of trays are revealed, hydrodynamic parameters of work of trays are determined: hydraulic resistance of a dry and irrigated tray, middle trays ablation of a liquid. On the basis of the offered scheme of forces action on the valve massexchange trays the technique of definition of the minimal and maximal speed in apertures of a plate in a mode of self-regulation is developed. Dependences for definition of factors masstransfer in gas and liquid phases are received. The engineering design procedure of valve trays with spherical valves is developed. The offered design of valve trays was introduced at modernization rectification set of oil stabilization on Kachanovka UCPO.

Published
2005

18. Modelización avanzada de columnas de destilación de operación discontinua

Author

Mehlhorn, Arndt, Universitat Politècnica de Catalunya. Departament d'Enginyeria Química, Puigjaner Corbella, Lluís, Espuña Camarasa, Antonio, and Espuña, Antonio

Subjects
Enginyeria química [Àrees temàtiques de la UPC], destilación discontinua, Destil·lació -- Tecnologia química, batch distillation, transferencia de materia, masstransfer, rate based approach
Abstract

La tesis doctoral se compone de dos partes fundamentales: El desarrollo teórico de un modelo de simulación para la destilación discontinua y la validación de este mediante experimentos hechos en una planta piloto de destilación discontinua. La parte teórica se divide en la parte de desarrollo del modelo y en la parte de la implementación del modelo en un programa de simulación. El nuevo modelo desarrollado es un modelo de transferencia de materia que se distingue de los desarrollos anteriores por su capacidad de contemplar la cinética de la transferencia de materia tal como la hidrodinámica. La incorporación de efectos hidrodinámicos se basa principalmente en la observación de diferentes geometrías de contacto en una columna de platos perforados. Estas geometrías de contacto son canales de vapor y burbujas. En caso de las burbujas se distingue entre grandes y pequeñas con diferentes propiedades hidrodinámicas. De esta forma el modelo contempla tres diferentes clases de vapor, dos clases de vapor de desequilibrio y una de equilibrio (burbujas pequeñas). Para las clases de vapor de desequilibrio se calcula explícitamente los caudales de materia que traviesen la interfase basándose en la teoría de Maxwell-Stefan de transferencia de materia multicomponente. La parte experimental se divide en la parte de diseño de la columna usada en una planta piloto y en la de la realización de los experimentos. El diseño de la columna tiene como objetivo la obtención de un medio de validación del nuevo modelo desarrollado. Por tanto está equipado con un gran número de sensores de temperatura, de presión y de tomas de muestra. También la realización de los experimentos se adapta al fin de la validación del modelo, ya que la frecuencia de toma de muestra y de capturación de señales de temperatura es elevada. La memoria de la tesis contiene una comparación amplia de los resultados experimentales con los de la simulación. Estas comparaciones demuestran una determinada superioridad del modelo desarrollado sobre desarrollos anteriores.

Published
1998

19. Modelización avanzada de columnas de destilación de operación discontinua

Author

Universitat Politècnica de Catalunya. Departament d'Enginyeria Química, Puigjaner Corbella, Lluís, Espuña Camarasa, Antonio, Mehlhorn, Arndt, Universitat Politècnica de Catalunya. Departament d'Enginyeria Química, Puigjaner Corbella, Lluís, Espuña Camarasa, Antonio, and Mehlhorn, Arndt

Abstract

La tesis doctoral se compone de dos partes fundamentales: El desarrollo teórico de un modelo de simulación para la destilación discontinua y la validación de este mediante experimentos hechos en una planta piloto de destilación discontinua. La parte teórica se divide en la parte de desarrollo del modelo y en la parte de la implementación del modelo en un programa de simulación. El nuevo modelo desarrollado es un modelo de transferencia de materia que se distingue de los desarrollos anteriores por su capacidad de contemplar la cinética de la transferencia de materia tal como la hidrodinámica. La incorporación de efectos hidrodinámicos se basa principalmente en la observación de diferentes geometrías de contacto en una columna de platos perforados. Estas geometrías de contacto son canales de vapor y burbujas. En caso de las burbujas se distingue entre grandes y pequeñas con diferentes propiedades hidrodinámicas. De esta forma el modelo contempla tres diferentes clases de vapor, dos clases de vapor de desequilibrio y una de equilibrio (burbujas pequeñas). Para las clases de vapor de desequilibrio se calcula explícitamente los caudales de materia que traviesen la interfase basándose en la teoría de Maxwell-Stefan de transferencia de materia multicomponente. La parte experimental se divide en la parte de diseño de la columna usada en una planta piloto y en la de la realización de los experimentos. El diseño de la columna tiene como objetivo la obtención de un medio de validación del nuevo modelo desarrollado. Por tanto está equipado con un gran número de sensores de temperatura, de presión y de tomas de muestra. También la realización de los experimentos se adapta al fin de la validación del modelo, ya que la frecuencia de toma de muestra y de capturación de señales de temperatura es elevada. La memoria de la tesis contiene una comparación amplia de los resultados experimentales con los de la simulación. Estas comparaciones demuestran una determinada super, Postprint (published version)

Published
1998

20. Modeling Of Membrane Solute Mass Transfer In Ro/nf Membrane Systems

Author

Zhao, Yu

Subjects
ASTM D 45160, Masstransfer, Membrane, NOM, Nanofiltration, Reverse osmosis, Surface characteristics, Civil and Environmental Engineering, Engineering, Dissertations, Academic -- Engineering and Computer Science; Engineering and Computer Science -- Dissertations, Academic
Abstract

Five articles describing the impact of surface characteristics, and development of mass transfer models for diffusion controlled membrane applications are published in this dissertation. Article 1 (Chapter 3) describes the impact of membrane surface characteristics and NOM on membrane performance for varying pretreatment and membranes during a field study. Surface charge, hydrophobicity and roughness varied significantly among the four membranes used in the study. Membrane surface characteristics, NOM and SUVA measurements were used to describe mass transfer in a low pressure RO integrated membrane system. Inorganic and organic solute and water mass transfer coefficients were systematically investigated for dependence on membrane surface properties and NOM mass loading. Inorganic MTCs were accurately described by a Gaussian distribution curve. Water productivity, NOM rejection and inorganic rejection increased as membrane surface charge and NOM loading increased. Inorganic MTCs were also correlated to surface hydrophobicity and surface roughness. The permeability change of identical membranes was related to NOM loading, hydrophobicity and roughness. Organic fouling as measured by water, organic and inorganic mass transfer was less for membranes with higher hydrophilicity and roughness. Article 2 (Chapter 4) describes the development of a diffusion controlled solute mass transfer model to assess membrane performance over time. The changing mass transfer characteristics of four low-pressure reverse osmosis (LPRO) membranes was correlated to feed stream water quality in a 2000 hour pilot study. Solute mass transfer coefficients (MTCs) were correlated to initial solute MTCs, solute charge, feed water temperature, monochloramine loading and organic loading (UV254). The model can be used to predict cleaning frequency, permeate water quality and sensitivity of permeate water quality to variation of temperature, organic and monochloramine mass loading. Article 3 (Chapter 5) describes a comparison of the long standing method of assessing membrane performance (ASTM D 45160 and another approach using mass transfer coefficients (MTCs) from the homogenous solution diffusion model (HSDM) using a common data set, water productivity and standardized salt passage. Both methods were shown to provide identical assessments of water productivity, however different assessments of salt passage. ASTM D 4516 salt passage is normalized for pressure and concentration and does not show the effects of flux, recovery, temperature or specific foulants on salt passage. However the MTC HSDM method is shown to consider all those effects and can be easily used to predict membrane performance at different sites and times of operation, whereas ASTM D 45160 can not. The HSDM MTC method of membrane evaluation is more versatile for assessment of membrane performance at varying sites and changing operational conditions. Article 4 (Chapter 6) describes the development of a fully integrated membrane mass transfer model that considers concentration, recovery and osmotic pressure for prediction of permeate water quality and required feed stream pressures. Osmotic pressure is incorporated into the model using correction coefficients that are calculated from boundary conditions determined from stream osmotic pressures of the feed and concentrate streams. Comparison to homogenous solution diffusion model (HSDM) with and without consideration of osmotic pressure and verification of IOPM using independently developed data from full and pilot scale plants is presented. The numerical simulation and statistical assessment show that osmotic pressure corrected models are superior to none-osmotic pressure corrected models, and that IOPM improves model predictability. Article 5 (Chapter 7) describes the development and comparison of a modified solution diffusion model and two newly developed artificial neural network models to existing mechanistic or empirical models that predict finished water quality for diffusion controlled membranes, which are generally restricted to specific solute MTCs that are site and stage specific. These models compensate for the effects of system flux, recovery and feed water quality on solute MTC and predict permeate water quality more accurately than existing models.

Published
2004

21. Hydrodynamics and oxygen balance in a high-rate algal pond

Author

El Hamouri, B., Boumansour, B. E., Dufayt, O., El Ouarghi, H., and Vasel, J.L.

Subjects
*HYDROLOGY, *SEWAGE purification, *SEWAGE, *HYDRODYNAMICS, *MICROBIOLOGY
Abstract

As for any other system used in wastewater treatment, it is important to know the mixing characteristics and net oxygen balance in high-rate algal ponds (HRAPs). The design of HRAPs obviously is conducive to plug flow, but with a large recirculation flow rate. The pond's treatment capacity will also depend on the net oxygen balance resulting from photosynthesis and respiration. In order to define an appropriate model describing the oxygen balance in the system, two techniques are respectively used for determining the hydrodynamic parameters and oxygen transfer coefficients of HRAPs. [ABSTRACT FROM AUTHOR]

Published
2000

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