Wyniki wyszukiwania - Biblioteka Nauki

1

Kinetics of zinc(ii) extraction from model hydrochloric acid solutions in the lewis cell

100%

Niemczewska J. , Alejski K. , Szymanowski J.

Environment Protection Engineering

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2005

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tom Vol. 31, nr 3-4

83-92

EN

Extraction of zinc(II) from model hydrochloric acid solutions was studied in the Lewis cell mixing the bulks of both phases and keeping a stable interfacial surface. Equilibrium extraction data were obtained in a classical way described in previous papers. All experiments were carried out at room temperature. MEDUSA program was used to estimate the distribution of zinc(II) chlorocomplexes in the aqueous feed. In the aqueous feed, zinc(II) is mainly in the form of (92 mole %). The contents of and are estimated as equal to 8 and 0 mole %, respectively. It was found that the Lewis cell experiments, although dynamic in nature, support the extraction of ZnCl2×2TBP chlorocomplex from model solutions containing 5 M Cl- and 0.55 M H+. The fluxes and mass transfer coefficients were estimated using two-layer model of mass transfer. The initial fluxes of zinc(II), HCl, Cl-, chloride present in the zinc(II) complex and water depend upon the concentration of tributyl phosphate and the mixing rates. The diffusion step in the organic phase gives a higher resistance to the mass transfer than the diffusion step in the aqueous phase. The physical transfer of small water molecules is less sensitive to the mixing rates than the transfer of bulky zinc(II) chlorocomplex.

2

Series solution of unsteady free convection flow with mass transfer along an accelerated vertical porous plate with suction

100%

Zaman H. , Ayub M.

Open Physics

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2010

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tom 8

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nr 6

931-939

EN

The problem of unsteady free convection flow is considered for the series solution (analytic solution). The flow is induced by an infinite vertical porous plate which is accelerated in its own plane. The series solution expressions for velocity field, temperature field and concentration distribution are presented. The influence of important parameters is seen on the velocity, temperature, concentration, skin friction coefficient and temperature gradient with the help of graphs and tables. Convergence is also properly checked for different values of the important parametes for velocity field, temperature and concentration with the help of ħ-curves.

3

Badanie przenoszenia ciepła i masy w chłodziarkach adsorpcyjnych

100%

Gwadera M. , Kupiec K.

Inżynieria i Aparatura Chemiczna

|

2014

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tom Nr 4

245--246

PL

W pracy przedstawiono wyniki badań doświadczalnych dotyczących adsorpcji w ziarnach adsorbentu naniesionych na powierzchnię rurki metalowej. Taka konstrukcja jest stosowana w adsorpcyjnych urządzeniach chłodniczych. Badania prowadzono w układzie silikażel – para wodna. Stosowano różne natężenia przepływu fazy gazowej i różne wielkości ziaren. Stwierdzono znaczny wpływ prędkości przepływu fazy gazowej na przebieg procesu.

EN

The experimental study results on adsorption in adsorbent pellets spread directly on a metal pipe surface are presented in the paper. Such construction is used in adsorption chillers. A silica gel - water vapour system was studied. Different gas phase flow rates and different sizes of silica gel pellets were used. It was found that gas phase velocity significantly influenced the process.

4

The Hybrid Numerical Model of Heat and Mass Transfer in Domain of Casting

100%

Mochnacki B. , Prażmowski M. , Suchy J.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2002

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tom z. 75

137-140

EN

In the paper the numerical model of solidification and segregation processes proceeding in the casting domain is discussed. The thermal processes described by the Fourier equation and the adequate physical, geometrical and boundary-initial conditions are simulated using the control volume method, while the segregation model bases on the collocation method described in (1). The coupling of the both algorithms results from the solidification rate (the heat transfer model) and changing solidification point (the segregation one). In the final part of the paper the example of numerical realization is shown.

5

Hydromagnetic unsteady mixed convectionand mass transfer flow past a vertical porous plate immersed in a porous medium with the hall effect

100%

Sharma B. K. , Chaudhary R. C.

Engineering Transactions

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2008

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tom Vol. 56, iss. 1

3-23

EN

The present work is concerned with unsteady mixed convection and mass transfer flow with Hall effect of an electrically conducting incompressible viscous fluid through a porous medium bounded by an infinite vertical plate subjected to suction/injection velocity in the presence of a constant magnetic field. The magnetic field is applied transversely to the direction of the flow. The resulting problem has been solved analytically and the solutions are found for velocity, temperaturę, concentration of the species, skin-friction, surface heat flux and mass flux. The effects of materiał parameters on the flow characteristics are expressed and illustrated/discussed by graphs and table.

6

Approximate characteristics of a moving temperature front in a fixed-bed catalytic reactor based on a heterogeneous reactor model

100%

Burghardt A. , Berezowski M. , Jacobsen E. W.

Inżynieria Chemiczna i Procesowa

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1999

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tom T. 20, z. 4

523-548

EN

The study deals with an non-stationary process of mass and heat transfer accompanied by a chemical reaction occurring in a catalytic reactor. The process has been described by a one-dimensional continuous two-phase model of the reactor. Based on the assumptions of the 'ideal thermal front' in the reactor, approximate solutions are obtained for the equations that describe the process. Relations are thus derived which define the principal properties of the thermal front, namely, its propagation velocity in the bed and the maximum temperature of the front. The above relations express these properties in terms of dimensionless numbers that characterise the chemical reaction taking place in the reactor and the operating parameters of the vessel. The formulas derived may be useful in the design of reactors with the periodic reversal of the feed mixture. They enable the effect to be analysed of the various operating parameters upon the propagation velocity of the thermal front and its maximum temperature, without resorting to tedious and time-consuming trial and error methods that require repeated integration of the model equations.

PL

Przeprowadzone w pracy rozważania dotyczą niestacjonarnego procesu transportu masy i ciepła z równocześnie przebiegającą reakcją chemiczną w reaktorze katalitycznym o stałym złożu. Proces ten opisano za pomocą jednowymiarowego ciągłego dwufazowego modelu reaktora. Korzystając z założeń 'idealnego frontu termicznego' w reaktorze, rozwiązano w sposób przybliżony równania opisujące rozważany proces i uzyskano zależności definiujące podstawowe właściwości frontu termicznego, a mianowicie szybkość propagacji w złożu i jego maksymalną temperaturę. Wzory te uzależniają wspomniane wyżej właściwości frontu termicznego od modułów bezwymiarowych charakteryzujących przebiegającą w reaktorze reakcję chemiczną oraz parametry reaktora. Wyprowadzone wzory mogą być bardzo pomocne przy projektowaniu reaktorów z rewersją mieszaniny zasilającej reaktor. Pozwalają one bowiem na zbadanie wpływu parametrów pracy reaktora z rewersją na szybkość propagacji frontu termicznego i jego maksymalna temperaturę bez uciekania się do żmudnej i pracochłonnej metody prób i błędów, polegającej na wielokrotnym całkowaniu równań modelu.

7

Experimental and theoretical studies on heat and mass transfer in anti-condensation coatings

100%

Rusowicz A. , Grzebielec A.

|

nr 3

8

Stagnation point flow of carbon nanotubes over stretching cylinder with slip conditions

100%

Hayat T. , Farooq M. , Alsaedi A.

Open Physics

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2015

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tom 13

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nr 1

EN

This work concentrates on stagnation point flow of a nanofluid over an impermeable stretching cylinder with mass transfer and slip effects. Carbon nanotubes (CNTs) and water are used as a nanofluid in the present investigation. Two types of CNTs are used as nanoparticles (i) Single-wall carbon nanotubes (SWCNTs) and (ii) multiwall carbon nanotubes (MWCNTs). Appropriate transformations are used to achieve a system of ordinary differential equations. Convergent series solutions are obtained. Behavior of various parameters on the velocity, temperature and concentration profiles are discussed graphically. Numerical values of skin friction coefficient, Nusselt number and Sherwood number are computed and analyzed.

9

Transport masy w kolumnach ze strukturalnym wypełnieniem reaktywnym

100%

Jaroszyński M. , Kołodziej A. , Bylica I.

Inżynieria Chemiczna i Procesowa

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2002

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tom T. 23, z. 4

495-506

PL

Przedstawiono wyniki badań transportu masy w fazie ciekłej i gazowej dla wypełnienia reaktywnego MULTIPAK. Do badań użyto kolumny o średnicy 250 mm oraz układów: dwutlenek węgla-powietrze-woda i amoniak-powietrze-woda. Wyniki badań eksperymentalnych opracowano w postaci równań korelacyjnych. Dokonano porównania intensywności wymiany masy dla rozpatrywanego wypełnienia MULTIPAK i dla trzech konwencjonalnych wypełnień strukturalnych.

EN

The results of the investigations of the mass transfer in the liquid and gas phases for the reactive packing MULTIPAK are presented. The studies have been carried out for a column 250 mm in diameter using carbon dioxide.air.water and ammonia.air.water systems. Basing at the experimental results, appropriate correlation equations have been elaborated. The comparison of the mass transfer intensity has been performed between the packing MULTIPAK and three conventional structured packings.

10

Mass transfer process of leaching weathered crust elution-deposited rare earth ore with magnesium salts

100%

Chen Z. , Zhang Z. , He Z. , Chi R.

Physicochemical Problems of Mineral Processing

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2018

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tom Vol. 54, iss. 3

1004--1013

EN

In order to optimize the leaching process of weathered crust elution-deposited rare earth ore with magnesium salts, the influence of different flow rate, concentration of magnesium ions, initial pH of magnesium salts solution and experimental temperature on the mass transfer process of rare earth and aluminum was investigated in the case of using magnesium salts as leaching agent. The relationship between the flow rate μ and the HETP (Height Equivalent of Theoretical Plate) is in accordance with the Van Deemter equation when magnesium salts were used as leaching agent. The optimum condition for rare earth and aluminum were 0.4 cm3/min of flow rate and 0.2 mol/dm3 of magnesium ion concentration of magnesium sulfate, magnesium chloride and magnesium nitrate respectively. Under this condition the mass transfer efficiency of rare earth and aluminum with three kinds of magnesium salts follow the order of Mg(NO3)2>Mg(Cl)2>MgSO4. High temperature contributes to improving the mass transfer efficiency of rare earth and aluminum. Magnesium nitrate as the leaching agent can get the highest leaching mass transfer efficiency of rare earth and magnesium sulfate as the leaching agent can make the impurity leaching and mass transfer efficiency of Al is the lowest.

11

Mathematical modelling of heat and mass transfer in a fixed biomass fuel bed. Part 3, Char Combustion

100%

Gemechu B. , Atreya A. , Blasiak W.

Archives of Thermodynamics

|

1999

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tom Vol. 20, no 3/4

73-88

EN

One-dimensional propagation of a combustion front in a solid fuel bed of char is modelling by making the solid fuel as stationary with gas flowing through it upwards. The main means of heat transfer considered are conduction, convection and radiation. The fuel bed is assumed to be a porous homogenous layer composed of uniformly distributed coarse particles that are randomly oriented. The bed is thermally thick rendering a time-dependent, non-uniform temperature distribution between the top and the bottom. The mathematical model formulates the basic equations and solves them numerically to describe the temperature and species distribution in the region. Thermal non-equilibrium between the gas phase and the solid particle syrfaces is assumed, cosequently the use of separate equations for gas and solid phase equations is necessary. The method of solution is more complicated due to the fact that the partial differential equations of heat transfer are simultaneous non-linear partial differential equations. Numerical methods are used applaying Mathematica and Fortran ODE codes. Both methods show good results compared with previous works.

12

Mathematical modelling of heat and mass transfer in a fixed biomass fuel bed. Part 1, Drying

100%

Gemechu B. , Atreya A. , Blasiak W.

Archives of Thermodynamics

|

1999

|

tom Vol. 20, no 3/4

49-61

EN

A one-dimensional quasi-steady state mathematical model of heat and mass transfer in a fixed bed of biomass fuel during drying is presented. Heat is transferred from the pyrolysing fuel bed to the drying fuel above it by conduction and convection. The gas flow rate is determined by mass flux flowing through the bed. The drying rate curve is analyzed theoretically and the best drying curve formula is chosen. As a result, a one-dimensional quasi-steady state mass and temperaturedistributions in the bed are determined. @eng

13

Mathematical modelling of heat and mass transfer in a fixed biomass fuel bed. Part 2, Pyrolysis

100%

Gemechu B. , Atreya A. , Blasiak W.

Archives of Thermodynamics

|

1999

|

tom Vol. 20, no 3/4

63-72

EN

Heat and mass transfer in a fixed bed of biomass during thermal degradation of biomass in a hot inert gas (pyrolysis) is modeled. Biomass fuel decomposes to give gas, tar and char as a result of hot gas flowing through it upwards from a combustion char below. The main heating mode at this stage is conduction and convection. The fuel bed is assumed to be a porous homogenous layer composedof uniformely distributed coarse particles that are randomly oriented. The mathematical model formulates the basic equations and solves them numerically to describe the temperature and solid fuel degradation to tar, gas and char. Thermal non-equilibrium between the gas phase and the solid particle surfaces is assumed, conseqently the use of separate equations for gas and solid phase equations is necessary

14

Volumetric liquid side mass transfer coefficient in a gas.liquid microreactor / Paweł Sobieszuk, Paweł Cygański, Ryszard Pohorecki

100%

Sobieszuk P. , Cygański P. , Pohorecki R.

Chemical and Process Engineering

|

2008

|

tom Vol. 29, z. 3

651-661

PL

Badano szybkość wymiany masy w przepływie gaz.ciecz w mikrokanale o przekroju okrągłym i średnicy 0,4 mm w warunkach przepływu Taylora. Zastosowano układ, w którym CO2 był absorbowany w buforze 0,3 M K2CO3/0,3 M KHCO3. Wyznaczono wartości objętościowego współczynnika wnikania masy po stronie cieczy dla różnych prędkości gazu i cieczy.

EN

Gas.liquid mass transfer during Taylor (slug) flow in a microchannel of circular cross section 0.4 mm in diameter was investigated. In the physicochemical system used, CO2 was absorbed from a CO2/N2 gaseous mixture into a K2CO3/KHCO3 aqueous solution. The liquid side volumetric mass transfer coefficient was measured, and its dependence on gas and liquid superficial velocities has been determined.

15

Badania wymiany masy dla dwóch wariantów wypełnienia katalitycznego KATAPAK-S

100%

Kołodziej A. , Jaroszyński M. , Bylica I.

Inżynieria Chemiczna i Procesowa

|

2004

|

tom T. 25, z. 3/2

1115-1120

PL

W pracy przedstawiono wyniki badań wnikania masy dla dwu wariantów wypełnienia reaktywnego KATAPAK-S przeprowadzonych w kolumnie o średnicy 250 mm, dla układów CO2-woda-powietrze i NH3-powietrze-woda. Uzyskane wyniki przedstawiono w formie wykresów i równań korelacyjnych. Rezultaty wykorzystywane są do modelowania procesów rektyfikacji katalitycznej.

EN

Mass transfer study is presented for two variants of catalytic packing KATAPAK-S. The study was performed in a 250 mm ID column, using the CO2-water-air and NH3-air-water systems. Results presented as charts and correlation equations are applied for modelling of catalytic distillation.

16

On the Influence of Chemical Modification of Silica on Its Porous Structure under Solvothermal Conditions

100%

Sidorchuk V. V. , Skubiszewska-Zięba J. , Charmas B. , Leboda R.

Polish Journal of Chemistry

|

2008

|

tom Vol. 82, nr 1-2

183-190

EN

Changes of porous structure of silica gels (aerosilogels) were studied during their chemical modification under various conditions, i.e. solvothermal at high temperature and pressure of reagents as well as in common treatment with substances of different chemical character without high pressure. Necessity of taking into account the effects of transfer of silica mass during its modification under the conditions of high pressure of modifying agent (organothermal treatment) on its porous structure parameters was pointed to.

17

Preparation of a solid product with high water content and water retention properties

88%

Cvijić M. , Golob J.

Polish Journal of Chemical Technology

|

2020

|

tom Vol. 22, nr 3

17--23

EN

This work presents the development of a solid product with a high water content (99.08%) and water retention properties. Water was chosen as a potential carrier of a volatile active substance and water retaining properties of material were studied at a temperatures and relative air humidity values with the support of the theory of drying. The study first confirmed the role of Gibbs’ phase rule in the research of solid-gas phase equilibrium, and second presented drying kinetics developed from Fick’s second law and expressed with the first term of the Fourier equation. Solutions of equations for phase equilibrium and mass transfer enabled the calculation of Luikov’s parameters, which are important for equilibrium relations and for the diffusivity of water in a solid for mass transfer prediction. The obtained thermodynamic and kinetic parameters enabled product characterisation that may be important for the prediction of retention times.

18

Effects of buoyancy and heterogeneous chemical reaction on unsteady convective diffusion of solute in a Boussinesq fluid flow

88%

Siddheshwar P. G. , Manjunath S.

Applied Mechanics and Engineering

|

1999

|

tom Vol. 4, no 4

739-757

EN

A closed - form solution is obtained for the problem concerning buoyancy - affected dispersion of solute in a Boussinesq fluid flow with wall - catalysed reaction. The long time Taylor (1953) and Aris (1956) regimes of dispersion for the present problem are obtained as limiting cases. The analytical result on dispersion of solute with wall catalysed reaction at long times is compared with the analytical solution when reaction is absent. The results have applications in heat exchangers, sediment - laden flows and extra - corporeal biomechanical situations.

19

Utilizing research fundamentals to improve wet Fluegas Desulfurization technology of ABB

88%

Brogren C. , Bengtsson S. , Rader P.

Archiwum Ochrony Środowiska

|

1999

|

tom Vol. 25, no. 3

11-31

EN

Drawing from 30 000 MW of world-wide FGD experience, ABB has developed a system designed to reduce the overall cost of SO2 compliance. The advanced wet scrubbing system is being demonstrated at Ohio Edison's Niles Plant at the 130 MW level. In the development work ABB has put a lot of effort into understanding of the two basic processes that determine the size of a wet FGD system, i.e. gas-liquid mass transfer of the droplets in the spray zone and the impact of various process parameters on the dissolution rate of limestone. This paper present the derived models and the results both in terms of scientific qualitative results but also how these results have been implemented into ABBs advanced WFGD system design.

20

Application of chromatographic plate theory on the weathered crust elution-deposited rare earth ore with carboxylate

88%

Zhang Z. , Wang G. , Li C. , Chi R. , Long F. , Chen Z. , Chi X. W. , Liu D.

Physicochemical Problems of Mineral Processing

|

2021

|

tom Vol. 57, iss. 4

48--62

EN

To improve the leaching process of rare earth and reduce the impurities in the leachate, the carboxylate ammonium, such as ammonium acetate, ammonium citrate and ammonium tartrate, were selected as lixiviant to compare the effects of concentration, flow rate, pH and temperature on leaching mass process of rare earth and aluminum. Meanwhile, the leaching behaviors of rare earth and aluminum leached by three kinds of carboxylate ammonium were analyzed by chromatographic plate theory. The relationship between the flow rate and height equivalent (HETP) could fit well with the Van Deemter equation and there was an optimal flow rate (uopt) for the leaching of the rare earth and aluminum. Besides, the conditions of carboxylate ammonium lixiviant were optimized. The optimum concentrations of ammonium acetate, ammonium tartrate and ammonium citrate were 15 g/L, 25 g/L and 5 g/L respectively, the leaching flow rate was 0.50 mL/min, the pH value was approximatively 7.00 and the leaching temperature was 293 K to 303 K. At these conditions, the mass transfer efficiencies of three ammonium carboxylates for rare earth and aluminum was in the order of ammonium acetate > ammonium tartrate > ammonium citrate. Moreover, the ammonium acetate could commendably inhibit aluminum ions entering the lixivium.