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Wyświetlanie 1-15 z 20
Tytuł:
The effect of ozone feeding mode on the effectiveness of NO oxidation
Autorzy:
Jakubiak, M.
Kordylewski, W.
Powiązania:
https://bibliotekanauki.pl/articles/185027.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
ozon
mieszanie
deNOx
ozone
mixing
Opis:
The influence of ozone injection mode on the effectiveness of nitrogen monoxide oxidation to nitrogen dioxide by ozone in a flow reactor was investigated experimentally in laboratory apparatus. Nitrogen monoxide was diluted to the mole fraction 100 ppm in air which served as the carrier gas flowing through the tube of the diameter D = 60 mm into which ozone was injected. The effects of a number of ozone injecting nozzles and their configuration on the effectiveness of NO oxidation were examined. In the closest vicinity from the injection site the counter-current injection mode appeared to be superior to the co-current injection mode, but in areas located further from the injection site both injection systems were almost equally effective.
Źródło:
Chemical and Process Engineering; 2011, 32, 3; 229-239
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Impact of carrageenan addition on rheological characterisation of some hydrocolloid aqueous solutions during long-lasting agitating with rotational speed changes
Autorzy:
Neupauer, Krzysztof
Kabziński, Maciej
Powiązania:
https://bibliotekanauki.pl/articles/185187.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
mixing
viscoelasticity
rheology
hydrocolloids
mieszanie
lepkosprężystość
reologia
hydrokoloidy
Opis:
The paper presents the impact of carrageenan addition on rheological characterisation of some hydrocolloid aqueous solutions during stirring with rotational speed changes. Carboxymethyl cellulose, guar gum and xanthan gum were used. Measurements were conducted in a vessel equipped with an anchor stirrer under rotational speed increase and decrease conditions, equivalent to a hysteresis loop rheological test. Rheological parameters were calculated using the power-law equation. It was found that a carrageenan addition generally causes a reduction of liquid apparent viscosity and time-dependent rheological behaviour intensification, with some exceptions.
Źródło:
Chemical and Process Engineering; 2019, 40, 4; 351--360
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of Large Eddy Simulations and κ-ε Modelling of Fluid Velocity and Tracer Concentration in Impinging Jet Mixers
Autorzy:
Wojtas, K.
Orciuch, W.
Makowski, Ł.
Powiązania:
https://bibliotekanauki.pl/articles/185361.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
jet mixer
mixing
PIV
PLIF
LES
mieszalnik strumieniowy
mieszanie
Opis:
Simulations of turbulent mixing in two types of jet mixers were carried out using two CFD models, large eddy simulation and k-ε model. Modelling approaches were compared with experimental data obtained by the application of particle image velocimetry and planar laser-induced fluorescence methods. Measured local microstructures of fluid velocity and inert tracer concentration can be used for direct validation of numerical simulations. Presented results show that for higher tested values of jet Reynolds number both models are in good agreement with the experiments. Differences between models were observed for lower Reynolds numbers when the effects of large scale inhomogeneity are important.
Źródło:
Chemical and Process Engineering; 2015, 36, 2; 251-262
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study of the Process of Hydraulic Mixing in Anaerobic Digester of Biogas Plant
Autorzy:
Karaeva, J.V.
Khalitova, G.R.
Kovalev, D.A.
Trakhunova, I.A.
Powiązania:
https://bibliotekanauki.pl/articles/185387.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
biogas
mixing
hydrodynamics
CFD modelling
biogaz
mieszanie
hydrodynamika
modelowanie CFD
Opis:
Two systems of hydraulic mixing in a vertical cylindrical anaerobic digester: standard and modernised are discussed in the paper. Numerical investigations that were carried out are focused on a study of hydrodynamic processes in an aerobic digester using two various systems of hydraulic mixing as well as on analysis of the efficiency of methane fermentation process accomplished under different geometric parameters of an anaerobic digester and systems of hydraulic mixing.
Źródło:
Chemical and Process Engineering; 2015, 36, 1; 101-112
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modelling the gas flow in permeate channel in membrane gas separation process
Autorzy:
Szwast, M.
Powiązania:
https://bibliotekanauki.pl/articles/185832.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
gas separation
perfect mixing
Peclet number
CFD
separacja gazów
mieszanie
Opis:
This paper analyses the real behaviour of the fluid in the channels of a three-end membrane module. The commonly accepted mathematical model of membrane separation of gas mixtures in such modules assumes a plug flow of fluid through the feed channel and perfect mixing in the permeate channel. This article discusses the admissibility of accepting such an assumption regarding the fluid behaviour in the permeate channel. Throughout analysis of the values of the Péclet number criterion, it has been demonstrated that in the industrial processes of membrane gas separation, the necessary conditions for the perfect mixing in the permeate channel are not met. Then, CFD simulations were performed in order to establish the real fluid behaviour in this channel. It was proved that in the permeate channel the fluid movement corresponds to the plug flow, with the concentration differences at both ends of the module being insignificant. In view of the observations made, the admissibility of concentration stability assumptions in the mathematical models for the permeate channel was discussed.
Źródło:
Chemical and Process Engineering; 2018, 39, 3; 271--280
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modelling of the Bubble Size Distribution in an Aerated Stirred Tank: Theoretical and Numerical Comparison of Different Breakup Models
Autorzy:
Kálal, Z.
Jahoda, M.
Fořt, I.
Powiązania:
https://bibliotekanauki.pl/articles/185190.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
CFD
mieszanie
ciecz-gaz
mixing
gas-liquid
population balance
bubble breakup
Opis:
The main topic of this study is the mathematical modelling of bubble size distributions in an aerated stirred tank using the population balance method. The air-water system consisted of a fully baffled vessel with a diameter of 0.29 m, which was equipped with a six-bladed Rushton turbine. The secondary phase was introduced through a ring sparger situated under the impeller. Calculations were performed with the CFD software CFX 14.5. The turbulent quantities were predicted using the standard k-ε turbulence model. Coalescence and breakup of bubbles were modelled using the MUSIG method with 24 bubble size groups. For the bubble size distribution modelling, the breakup model by Luo and Svendsen (1996) typically has been used in the past. However, this breakup model was thoroughly reviewed and its practical applicability was questioned. Therefore, three different breakup models by Martínez-Bazán et al. (1999a, b), Lehr et al. (2002) and Alopaeus et al. (2002) were implemented in the CFD solver and applied to the system. The resulting Sauter mean diameters and local bubble size distributions were compared with experimental data.
Źródło:
Chemical and Process Engineering; 2014, 35, 3; 331-348
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hydraulic mixing modelling in reactor for biogas production
Autorzy:
Chmielewski, A. G.
Berbeć, A.
Zalewski, M.
Dobrowolski, A.
Powiązania:
https://bibliotekanauki.pl/articles/185258.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
biogas
biomass mixing
bioreactor
CFD modeling
biogaz
mieszanie biomasy
bioreaktor
modelowanie CFD
Opis:
Two-stage biogas production plant consists of two reactors: a hydrolyser and a fermentor. The bioreactor construction has to meet three requirements: low cost and simplicity of construction and good biomass mixing conditions with an application of appropriate method. This paper reports CFD modelling of hydraulic mixing in the tank to be applied in a two-stage industrial installation.
Źródło:
Chemical and Process Engineering; 2012, 33, 4; 621-628
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical Analysis Of Mixing Under Low And High Frequency Pulsations At Serpentine Micromixers
Autorzy:
Malecha, Z. M.
Malecha, K.
Powiązania:
https://bibliotekanauki.pl/articles/185164.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
aktywne mieszanie
symulacja numeryczna
technologia LTCC
serpentine micromixer
active mixing
numerical simulations
LTCC technology
Opis:
The numerical investigation of the mixing process in complex geometry micromixers, as a function of various inlet conditions and various micromixer vibrations, was performed. The examined devices were two-dimensional (2D) and three-dimensional (3D) types of serpentine micromixers with two inlets. Entering fluids were perturbed with a wide range of the frequency (0 – 50 Hz) of pulsations. Additionally, mixing fluids also entered in the same or opposite phase of pulsations. The performed numerical calculations were 3D to capture the proximity of all the walls, which has a substantial influence on microchannel flow. The geometry of the 3D type serpentine micromixer corresponded to the physically existing device, characterised by excellent mixing properties but also a challenging production process (Malecha et al., 2009). It was shown that low-frequency perturbations could improve the average mixing efficiency of the 2D micromixer by only about 2% and additionally led to a disadvantageously non-uniform mixture quality in time. It was also shown that high-frequency mixing could level these fluctuations and more significantly improve the mixing quality. In the second part of the paper a faster and simplified method of evaluation of mixing quality was introduced. This method was based on calculating the length of the contact interface between mixing fluids. It was used to evaluate the 2D type serpentine micromixer performance under various types of vibrations and under a wide range of vibration frequencies.
Źródło:
Chemical and Process Engineering; 2014, 35, 3; 369-385
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The effect of vessel scale on gas hold-up in gas-liquid systems
Autorzy:
Cudak, Magdalena
Powiązania:
https://bibliotekanauki.pl/articles/2034059.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
agitated vessel
mixing
gas hold-up
aqueous sucrose solution
mieszanie
zatrzymywanie gazu
wodny roztwór sacharozy
Opis:
The aim of the research presented in this paper was to determine the effect of vessel scale on gas hold- up in gas-liquid systems. The agitated vessel with internal diameters of T = 0:288 m and T = 0:634 m was filled with a liquid up to the height H = T. For the purpose of measurements, two high-speed impellers were used: Rushton turbine impeller (RT) or A 315 impeller.Within the study, the following parameters were altered: superficial gas velocity, impeller speed, impeller type and concentration of aqueous sucrose solution. In addition, influence of the vessel scale on gas hold-up value was analysed. Experimental results were mathematically described. Equations (5)–(7) do not have equivalents in the literature.
Źródło:
Chemical and Process Engineering; 2020, 41, 4; 241-256
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Energetic Efficiency of Mixing and Mass Transfer in Single Phase and Two-Phase Systems
Autorzy:
Bałdyga, J.
Jasińska, M.
Powiązania:
https://bibliotekanauki.pl/articles/184853.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
chemical test reaction
energetic efficiency
mass transfer
mixing
chemiczne reakcje testowe
wydajność energetyczna
transfer masy
mieszanie
Opis:
In this work a concept of energetic efficiency of mixing is presented and discussed; a classical definition of mixing efficiency is modified to include effects of the Schmidt number and the Reynolds number. Generalization to turbulent flows is presented as well. It is shown how the energetic efficiency of mixing as well as efficiencies of drop breakage and mass transfer in twophase liquid-liquid systems can be identified using mathematical models and test chemical reactions. New expressions for analyzing efficiency problem are applied to identify the energetic efficiency of mixing in a stirred tank, a rotor stator mixer and a microreactor. Published experimental data and new results obtained using new systems of test reactions are applied. It has been shown that the efficiency of mixing is small in popular types of reactors and mixers and thus there is some space for improvement.
Źródło:
Chemical and Process Engineering; 2017, 38, 1; 79-96
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of kinetics of multicomponent, heterogeneous granular mixtures – Laminar and turbulent flow approach
Autorzy:
Królczyk, J. B.
Powiązania:
https://bibliotekanauki.pl/articles/184979.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
mixing
granular materials
kinetics
turbulent stage
laminar stage
mieszanie
materiał sypki
kinetyka
etap burzliwy
etap laminarny
Opis:
Mixing of granular materials is unquestionably important. Mixing solids is common in industrial applications and frequently represents a critical stage of the processes. The effect of mixing determines the quality of the products. Achieving a gas or liquid mixture ideally homogeneous in terms of composition in the case of dissolving components is not that difficult, while in case of granular materials that usually differ in sizes and densities, obtaining a homogenous mixture is practically impossible. The aim of the paper is to present the kinetics of mixing of a multicomponent, nonhomogeneous granular mixture. For the first time in mixing of granular materials, a reference has been made to the terminology used in kinematics of fluid mixtures to determine the state of the mixture: turbulent or laminar. By means of statistical analysis the mixing process was divided into two stages. The initial phase of the process was called the stage of turbulent changes, due to large differences in the quality of the observed mixtures; the final step of the process was called the stage of laminar, stable changes, where further mixing did not result in a significant improvement in quality. The research was conducted in industrial conditions in a two-tonne mixer.
Źródło:
Chemical and Process Engineering; 2016, 37, 2; 161-173
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Computational Fluid Dynamics and Experimental Studies of a New Mixing Element in a Static Mixer as a Heat Exchanger
Autorzy:
Konopacki, M.
Kordas, M.
Fijałkowski, K.
Rakoczy, R.
Powiązania:
https://bibliotekanauki.pl/articles/185462.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
mixing
heat transfer process
static mixer
CFD
process intensification
mieszanie
proces przenikania ciepła
mieszalnik statyczny
intensyfikacja
Opis:
The main aim of this work is to study the thermal efficiency of a new type of a static mixer and to analyse the flow and temperature patterns and heat transfer efficiency. The measurements were carried out for the static mixer equipped with a new mixing insert. The heat transfer enhancement was determined by measuring the temperature profiles on each side of the heating pipe as well as the temperature field inside the static mixer. All experiments were carried out with varying operating parameters for four liquids: water, glycerol, transformer oil and an aqueous solution of molasses. Numerical CFD simulations were carried out using the two-equation turbulence k-ω model, provided by ANSYS Workbench 14.5 software. The proposed CFD model was validated by comparing the predicted numerical results against experimental thermal database obtained from the investigations. Local and global convective heat transfer coefficients and Nusselt numbers were detrmined. The relationship between heat transfer process and hydrodynamics in the static mixer was also presented. Moreover, a comparison of the thermal performance between the tested static mixer and a conventional empty tube was carried out. The relative enhancement of heat transfer was characterised by the rate of relative heat transfer intensification.
Źródło:
Chemical and Process Engineering; 2015, 36, 1; 59-72
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modeling and simulation of an ideal plug flow reactor for synthesis of ethyl oleate using homogeneous acid catalyst
Autorzy:
Barno, Suondos K.A.
Rashid, Sarmad A.
Abbas, Ammar S.
Powiązania:
https://bibliotekanauki.pl/articles/2034051.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
kinetics
simulation
ethyl oleate
product distribution
back-mixing
kinetyka
symulacja
oleinian etylu
dystrybucja produktu
mieszanie wsteczne
Opis:
The production of ethyl oleate, by homogenous acid esterification of oleic acid with ethanol, have discussed experimentally and via computational simulation in a plug flow reactor. An innovative simulation model has developed to predict the esterification reaction performance in an ideal plug flow reactor. The amount of H2SO4 acid catalyst, the initial molar ratio of alcohol to oleic acid, ethanol concentration, reaction temperature, and esterification time have examined their effects on ethyl oleate production and the conversion of oleic acid. Then the simulation extended to examine the esterification reaction kinetics and determine the reaction rate coefficients. The simulation results demonstrate that the increasing of H2SO4 acid, initial molar ratio of ethanol to oleic acid, ethanol concentration, and reaction temperature improved the productivity of the ethyl oleate and reduced the reactor space-time. The kinetics results illustrated that the reaction sensitivity to the temperature unchanging by using higher ethanol concentration and alcohol to oleic acid initial ratio. Lastly, the experimental yields at different conditions were slightly higher from those simulating with average values of 93.62 and 92.29%, respectively, indicating that the phenomenon of back-mixing cannot be ignored in esterification reactors, especially with a relatively high retention time within the reactor.
Źródło:
Chemical and Process Engineering; 2021, 42, 1; 53-68
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental and numerical investigation of axialand tangential forces in a stirred tank with yield-stress fluids
Autorzy:
Story, Anna
Story, Grzegorz
Jaworski, Zdzisław
Powiązania:
https://bibliotekanauki.pl/articles/2086783.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
mixing
yield-stress fluid
axial force
tangential force
CFD
mieszanie
płyn do granicy plastyczności
siła osiowa
siła styczna
Opis:
Complex rheological properties of yield-stress materials may lead to the generation of an intensive mixing zone near a rotating impeller. From the practical point of view, the zone should cover most of the stirred liquid. According to the literature review, several parameters may affect the size of the mixing zone, in particular forces exerted on the liquid. This paper presents both experimental and numerical investigation of axial and tangential forces generated during mechanical mixing of yield-stress fluids in a stirred tank. The tested fluids were aqueous solutions of Carbopol Ultrez 30 of concentration either 0.2 or 0.6 wt% and pH = 5.0. The study was performed for three types of impeller, pitched blade turbine, Prochem Maxflo T and Rushton turbine, in a broad range of their rotational speed, = 60 − 900 rpm. The axial and tangential forces were calculated from the apparent mass of the stirred tank and torque, respectively. The experimental results were compared with CFD predictions, revealing their good agreement. Analysis of the generated forces showed that they are dependent on the rheological characteristic of liquid and the impeller type. It was also found that although axial force was smaller than tangential force, it significantly increased the resultant force.
Źródło:
Chemical and Process Engineering; 2021, 42, 2; 173--190
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of impeller shape on solid particle suspension
Autorzy:
Rieger, F.
Jirout, T.
Ceres, D.
Seichter, P.
Powiązania:
https://bibliotekanauki.pl/articles/185746.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
mixing
axial impeller
hydrofoil impeller
just-suspended impeller speed
electrochemical metod
mieszanie
wirnik osiowy
prędkość wirnika
metoda elektrochemiczna
Opis:
This paper deals with the effect of impeller shape on off-bottom particle suspension. On the basis of numerous suspension measurements, correlations are proposed for calculating the just-suspended impeller speed for a standard pitched four-blade turbine and three types of hydrofoil impellers produced by TECHMIX for several particle sizes and for a wide range of particle concentrations. The suspension efficiency of the tested impellers is compared with the efficiency of a standard pitched blade turbine on the basis of the power consumption required for off-bottom suspension of solid particles. It is shown that the standard pitched blade turbine needs highest power consumption, i.e. it exhibits less efficiency for particle suspension than hydrofoil impellers produced by TECHMIX.
Źródło:
Chemical and Process Engineering; 2013, 34, 1; 139-152
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 20

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