Approximate Solution of Momentum Transfer in System Generalized Newtonian Fluid-Fluidized Bed of Spherical Particles Using Modified Rabinowitsch-Mooney Equation

1995 ◽  
Vol 60 (8) ◽  
pp. 1281-1296 ◽  
Author(s):  
Václav Dolejš ◽  
Petr Mikulášek ◽  
Petr Doleček
Keyword(s):  
Approximate Solution ◽  
Momentum Transfer ◽  
Fluidized Bed ◽  
Newtonian Fluid ◽  
Particle Diameter ◽  
Flow Region ◽  
Creeping Flow ◽  
Spherical Particles ◽  
Generalized Newtonian Fluid ◽  
Mooney Equation

The modified Rabinowitsch-Mooney equation together with the corresponding relations for consistency variables has been adopted for approximate solution of momentum transfer between generalized Newtonian fluid with laminar flow and surface of fluidized bed of spherical particles inclusive of wall surface. The solution has been concretized for a fluid characterized by power-law and Ellis flow models in the creeping flow region. The range of values of ratios of particle diameter to column diameter and that of porosity values e in which the suggested relation satisfactorily agrees with experimental results for pseudoplastic fluids have been delimitated experimentally.

Approximate Calculation of Pressure Drop in Laminar Flow of Generalized Newtonian Fluid Through Channels with Insert

1995 ◽  
Vol 60 (9) ◽  
pp. 1476-1491
Author(s):  
Václav Dolejš ◽  
Petr Doleček ◽  
Ivan Machač ◽  
Bedřich Šiška
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Laminar Flow ◽  
Numerical Solution ◽  
Newtonian Fluid ◽  
Calculation Method ◽  
Approximate Calculation ◽  
Creeping Flow ◽  
Experimental Results ◽  
Generalized Newtonian Fluid

An equation of Rabinowitsch-Mooney type has been suggested for approximate calculation of pressure drop in flow of generalized Newtonian fluid through channels with insert both in the region of creeping flow and at higher values of the Reynolds number, and this calculation method has been verified for four types of insert using own numerical solution and experimental results as well as literature data.

Model of fluidized bed expansion

1979 ◽  
Vol 44 (1) ◽  
pp. 50-55
Author(s):  
Benitto Mayrhofer ◽  
Lubomír Neužil ◽  
František Procháska
Keyword(s):  
Experimental Data ◽  
Fluidized Bed ◽  
Fixed Bed ◽  
Theoretical Models ◽  
Creeping Flow ◽  
Spherical Particles ◽  
Bed Porosity ◽  
Porosity Dependence ◽  
Bed Expansion ◽  
Better Than

Theoretical relations have been derived for the superficial velocity of fluidization under the creeping flow regime for cubic, monoclinic and tetrahedron configurations of spherical particles. The models proposed have been compared with theoretical models published up to the present and with the power-law correlations recommended. The configuration fitting the best was found to be the tetrahedron one. All configurations examined in this work gave correct trend of the velocity of fluidization versus porosity dependence. Experimental data indicate that for the bed porosity ranging between 0.45 and 0.68 our models are better than other so far published. However theoretical models of other authors based on the analysis of the behavior of a fixed bed give better results.

Adsorption of safranine T from aqueous medium by nano mesoporous MCM-41: adsorption equilibrium, kinetics, and thermodynamics

2020 ◽  
Vol 10 ◽  
Author(s):  
Xiao-Dong Li ◽  
Qing-Zhou Zhai
Keyword(s):  
Electron Microscopy ◽  
Ph Value ◽  
Particle Diameter ◽  
Spherical Particles ◽  
Practical Significance ◽  
Average Particle ◽  
Average Pore ◽  
Kinetics And Thermodynamics ◽  
Safranine T ◽  
Mcm 41

Introduction: In industrial production, a small amount of saffron T emissions will cause increase of water color and increase of chemical oxygen consumption, so study of the decolorization of saffron T wastewater has an important practical significance. Methods: MCM (Mobil Composition of Matter)-41 molecular sieve was synthesized by hydrothermal method. Power Xray diffraction and scanning electron microscopy were used to characterize the sample. Safranine T dye was adsorbed from water by the MCM-41 prepared. Kinetics and thermodynamics of the adsorption were studied. Results: The MCM-41 sample presented spherical particles and regular. The BET (Brunner-Emmett-Teller) specific surface area of the sample determined by 77 K low temperature nitrogen adsorption-desorption isotherm was 932 m2 /g. Its average particle diameter was 110 nm. TEM (transmission electron microscopy) results showed that the sample structure presented a honeycomb pore structure and the average pore diameter was 3.0 nm. The results showed that when room temperature was 20 ± 1 ℃, adsorbate safranine T: adsorbent MCM-41 = 20 : 1，the optimum pH value of adsorption was 4.0 and contact time was 20 min, the adsorption rate reached 98.29% and the adsorption capacity was 19.66 mg/g. The entropy change and enthalpy change of the adsorption system are respectively ΔS0 = 157.5 J/(mol·K); ΔH0 = 21.544 kJ/mol. When temperature was 277.15, 293.15, 303.15 K，the free energy change was respectively △G1 0 = -22.107 kJ/mol, △G2 0 = -24.627 kJ/mol, △G3 0 = -26.202 kJ/mol. Conclusion: The adsorption of safranine T by MCM-41 belongs to a pseudo-second-order adsorption. This adsorption accords with the Freundlich equation and belongs to a heterogeneous adsorption. The adsorption is an endothermic reaction of entropy increase, being spontaneous.

Effect of Fluidized Bed on Permeate Flux in Ceramic Membrane Cross-Flow Microfiltration

1995 ◽  
Vol 60 (12) ◽  
pp. 2074-2084
Author(s):  
Petr Mikulášek
Keyword(s):  
Fluidized Bed ◽  
Ceramic Membrane ◽  
Cross Flow ◽  
Experimental System ◽  
Experimental Results ◽  
Spherical Particles ◽  
Permeate Flux ◽  
Model Fluid ◽  
Optimum Porosity ◽  
Tubular Membranes

The microfiltration of a model fluid on an α-alumina microfiltration tubular membrane in the presence of a fluidized bed has been examined. Following the description of the basic characteristic of alumina tubular membranes, model dispersion and spherical particles used, some comments on the experimental system and experimental results for different microfiltration systems are presented. From the analysis of experimental results it may be concluded that the use of turbulence-promoting agents resulted in a significant increase of permeate flux through the membrane. It was found out that the optimum porosity of fluidized bed for which the maximum values of permeate flux were reached is approximately 0.8.

CFD‐DEM analysis of the spouted fluidized bed with non‐spherical particles

2021 ◽  
Author(s):  
Behrad Esgandari ◽  
Shahab Golshan ◽  
Reza Zarghami ◽  
Rahmat Sotudeh‐Gharebagh ◽  
Jamal Chaouki
Keyword(s):  
Fluidized Bed ◽  
Spherical Particles ◽  
Dem Analysis

scholarly journals Influence of Macroscopic Wall Structures on the Fluid Flow and Heat Transfer in Fixed Bed Reactors with Small Tube to Particle Diameter Ratio

Processes ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 689
Author(s):  
Thomas Eppinger ◽  
Nico Jurtz ◽  
Matthias Kraume
Keyword(s):  
Heat Transfer ◽  
Fixed Bed ◽  
Particle Diameter ◽  
Diameter Ratio ◽  
Spherical Particles ◽  
Reactor Wall ◽  
Entry Length ◽  
Fixed Bed Reactors ◽  
Wall Structures ◽  
Small Tube

Fixed bed reactors are widely used in the chemical, nuclear and process industry. Due to the solid particle arrangement and its resulting non-homogeneous radial void fraction distribution, the heat transfer of this reactor type is inhibited, especially for fixed bed reactors with a small tube to particle diameter ratio. This work shows that, based on three-dimensional particle-resolved discrete element method (DEM) computational fluid dynamics (CFD) simulations, it is possible to reduce the maldistribution of mono-dispersed spherical particles near the reactor wall by the use of macroscopic wall structures. As a result, the lateral convection is significantly increased leading to a better radial heat transfer. This is investigated for different macroscopic wall structures, different air flow rates (Reynolds number Re = 16 ...16,000) and a variation of tube to particle diameter ratios (2.8, 4.8, 6.8, 8.8). An increase of the radial velocity of up to 40%, a reduction of the thermal entry length of 66% and an overall heat transfer increase of up to 120% are found.

Peristaltic Motion of a Generalized Newtonian Fluid Through a Porous Medium

2000 ◽  
Vol 69 (2) ◽  
pp. 401-407 ◽  
Author(s):  
Elsayed F. Elshehawey ◽  
Ayman M. F. Sobh ◽  
Elsayed M. E. Elbarbary
Keyword(s):  
Porous Medium ◽  
Newtonian Fluid ◽  
Peristaltic Motion ◽  
Generalized Newtonian Fluid
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