scholarly journals A Study of Fluctuation and Expansion Ratios for Gas-Solid Fluidized Columns

2020 ◽  
Vol 26 (10) ◽  
pp. 15-34
Author(s):  
Maha MuhyiAlwanA Alhussaini ◽  
Hassanain Abbas Hassan ◽  
Nada Sadoon Ahmedzeki
Keyword(s):  
Experimental Results ◽  
Correlation Equations ◽  
Direct Relation ◽  
Column Diameter ◽  
Air Velocity ◽  
Minimum Fluidization Velocity ◽  
Bed Height ◽  
Bed Material ◽  
Fluidizing Medium ◽  
Good Agreement

The fluctuation and expansion ratios have been studied for cylindrical gas-solid fluidized columns by using air as fluidizing medium and Paracetamol as the bed material. The variables were the column diameter (0.0762, 0.15, and 0.18 m), static bed height (0.05, 0.07, and 0.09 m), and air velocity to several times of minimum fluidization velocity. The results showed that both the fluctuation and expansion ratios had a direct relation with air velocity and an inverse one with column diameter and static bed height. A good agreement was between the experimental results and the calculated values by using the correlation equations from the literature.

scholarly journals A Study of the Hydrodynamics Behavior of Cylindrical Gas-Solid Fluidized Beds for pharmaceutical material “Paracetamol “

2020 ◽  
Vol 26 (5) ◽  
pp. 191-210
Author(s):  
Maha Muhyi Alwan
Keyword(s):  
Fluidized Beds ◽  
Experimental Results ◽  
Inverse Relation ◽  
Direct Relation ◽  
Column Diameter ◽  
Type B ◽  
Minimum Fluidization Velocity ◽  
Fluidization Velocity ◽  
Bed Height ◽  
Minimum Fluidization

The hydrodynamics behavior of gas - solid fluidized beds is complex and it should be analyzed  and understood due to its importance in the design and operating of the units. The effect of column inside diameter and static bed height on the minimum fluidization velocity, minimum bubbling velocity, fluidization index, minimum slugging velocity and slug index have been studied experimentally and theoretically for three cylindrical columns of 0.0762, 0.15 and 0.18 m inside diameters  and 0.05, 0.07 and 0.09 m static bed heights .The experimental results showed that the minimum fluidization and bubbling velocities had a direct relation with column diameter and static bed height .The minimum slugging velocity had an inverse relation with static bed height and a direct one with column diameter .There was no agreement between the experimental and calculated values of Umb for Di=0.0762m ,this was a result to the assumption used in the correlation development. The fluidization index values were around 1 in all cases and that proved that the material is of Geldart type B. There was not a significant dependence of fluidization index and slug index on static bed height and column diameter.       

The effect of column diameter and bed height on minimum fluidization velocity

AIChE Journal ◽  
2010 ◽  
pp. NA-NA ◽  
Author(s):  
Akhil Rao ◽  
Jennifer S. Curtis ◽  
Bruno C. Hancock ◽  
Carl Wassgren
Keyword(s):  
Column Diameter ◽  
Minimum Fluidization Velocity ◽  
Fluidization Velocity ◽  
Bed Height ◽  
Minimum Fluidization

On the Modeling of Gas-Solid Fluidization: Which Physics Are Most Important to Capture?

2010 ◽  
Author(s):  
Francine Battaglia ◽  
Jonas A. England ◽  
Santhip Kanholy ◽  
Mirka Deza
Keyword(s):  
Experimental Data ◽  
Pressure Drop ◽  
Packing Fraction ◽  
Walnut Shell ◽  
Minimum Fluidization Velocity ◽  
Fluidization Velocity ◽  
Bed Height ◽  
Minimum Fluidization ◽  
Two Parameters ◽  
Bed Material

Recent studies to predict biomass fluidization hydrodynamics motivated a new study to reassess how to model gas-solid characteristics that capture the same physics as that measured in experiments. An Eulerian-Eulerian multifluid model was used to simulate and analyze gas-solid hydrodynamic behavior of the fluidized beds. The relations for the pressure drop measured at fluidization were used to correct for the bed mass by either adjusting the initial solids packing fraction or initial bed height, two parameters that must be specified in a CFD model. Simulations using sand as the bed medium were compared with experiments and it was found that adjusting the bulk density, or in other words, the initial solids volume packing, correctly predicted the pressure drop measured experimentally, but significantly under-predicted the minimum fluidization velocity. By adjusting the initial bed height to correct for the mass, both the pressure drop and minimum fluidization velocity were successfully predicted. Ground walnut shell and ground corncob were used as biomass media and simulations were performed for two reactor bed diameters by simply adjusting the initial bed height to match the measured pressure drop. All of the simulations correctly predicted the pressure drop curves of the experimental data. Further examination of the simulations and experimental data for walnut shell confirmed that adjusting the bed height was the best approach to model fluidization without artificially altering the physics and retaining the known characteristics of the bed material.

scholarly journals Effects of Coffee Form and Distributor Hole Angle on The Fluidization Behavior and Specific Energy Consumption in The Fluidized Bed Machine

2021 ◽  
Vol 84 (2) ◽  
pp. 152-158
Author(s):  
Thatchapol Chungcharoen ◽  
Warunee Limmun ◽  
Sansanee Sansiribhan
Keyword(s):  
Energy Consumption ◽  
Pressure Drop ◽  
Fluidized Bed ◽  
Specific Energy ◽  
Specific Energy Consumption ◽  
Experimental Result ◽  
Air Velocity ◽  
Minimum Fluidization Velocity ◽  
Robusta Coffee ◽  
Bed Height

The fluidized bed technique was applied to use with the Robusta coffee in this research. fluidization behavior and specific energy consumption were investigated under various coffee forms and distributor hole angles. Moreover, the minimum fluidization velocity (Vmf) was also determined. Experiments are carried out in a sample bed height of 5 cm with ambience air. In this study, two coffee forms (Ripe coffee cherries; RCC and parchment coffee; PC) and three distributor hole angles (45º, 60º and 90º) are examined. The experimental result shown that the fluidization behavior is influenced by coffee form and distributor hole angle. The RCC and distributor hole angle of 60º provided the low pressure drop throughout the superficial air velocity. The low values of Vmf and SEC were also achieved in the RCC and distributor hole angle of 60º.

Inducing Frictional Force to Enhance the Transient Response in Beams

2019 ◽  
Vol 22 (2) ◽  
pp. 88-93
Author(s):  
Hamed Khanger Mina ◽  
Waleed K. Al-Ashtrai
Keyword(s):  
Numerical Analysis ◽  
Transient Response ◽  
Frictional Force ◽  
Damping Ratio ◽  
Experimental Results ◽  
Damping Capacity ◽  
Tightening Force ◽  
Contact Areas ◽  
Good Agreement ◽  
Ansys Workbench

This paper studies the effect of contact areas on the transient response of mechanical structures. Precisely, it investigates replacing the ordinary beam of a structure by two beams of half the thickness, which are joined by bolts. The response of these beams is controlled by adjusting the tightening of the connecting bolts and hence changing the magnitude of the induced frictional force between the two beams which affect the beams damping capacity. A cantilever of two beams joined together by bolts has been investigated numerically and experimentally. The numerical analysis was performed using ANSYS-Workbench version 17.2. A good agreement between the numerical and experimental results has been obtained. In general, results showed that the two beams vibrate independently when the bolts were loosed and the structure stiffness is about 20 N/m and the damping ratio is about 0.008. With increasing the bolts tightening, the stiffness and the damping ratio of the structure were also increased till they reach their maximum values when the tightening force equals to 8330 N, where the structure now has stiffness equals to 88 N/m and the damping ratio is about 0.062. Beyond this force value, increasing the bolts tightening has no effect on stiffness of the structure while the damping ratio is decreased until it returned to 0.008 when the bolts tightening becomes immense and the beams behave as one beam of double thickness.

PHOTOINDUCED NONLINEAR OCTUPOLAR POLARIZATION: TRANSIENT AND PERMANENT REGIMES

1996 ◽  
Vol 05 (04) ◽  
pp. 653-670 ◽  
Author(s):  
CÉLINE FIORINI ◽  
JEAN-MICHEL NUNZI ◽  
FABRICE CHARRA ◽  
IFOR D.W. SAMUEL ◽  
JOSEPH ZYSS
Keyword(s):  
Theoretical Analysis ◽  
Second Harmonic ◽  
Experimental Results ◽  
Polar Field ◽  
Rotational Spectrum ◽  
Dual Frequency ◽  
One Dimensional ◽  
Ethyl Violet ◽  
Disperse Red 1 ◽  
Good Agreement

An original poling method using purely optical means and based on a dual-frequency interference process is presented. We show that the coherent superposition of two beams at fundamental and second-harmonic frequencies results in a polar field with an irreducible rotational spectrum containing both a vector and an octupolar component. This enables the method to be applied even to molecules without a permanent dipole such as octupolar molecules. After a theoretical analysis of the process, we describe different experiments aiming at light-induced noncentrosymmetry performed respectively on one-dimensional Disperse Red 1 and octupolar Ethyl Violet molecules. Macroscopic octupolar patterning of the induced order is demonstrated in both transient and permanent regimes. Experimental results show good agreement with theory.

scholarly journals Comparison of Experimental and Numerical Transient Drop Deformation during Transition through Orifices in High-Pressure Homogenizers

2021 ◽  
Vol 5 (3) ◽  
pp. 32
Author(s):  
Benedikt Mutsch ◽  
Peter Walzel ◽  
Christian J. Kähler
Keyword(s):  
High Pressure ◽  
Visual Analysis ◽  
Imaging Technique ◽  
Extensional Flow ◽  
Droplet Breakup ◽  
Experimental Results ◽  
Drop Deformation ◽  
Droplet Deformation ◽  
Shadow Imaging ◽  
Good Agreement

The droplet deformation in dispersing units of high-pressure homogenizers (HPH) is examined experimentally and numerically. Due to the small size of common homogenizer nozzles, the visual analysis of the transient droplet generation is usually not possible. Therefore, a scaled setup was used. The droplet deformation was determined quantitatively by using a shadow imaging technique. It is shown that the influence of transient stresses on the droplets caused by laminar extensional flow upstream the orifice is highly relevant for the droplet breakup behind the nozzle. Classical approaches based on an equilibrium assumption on the other side are not adequate to explain the observed droplet distributions. Based on the experimental results, a relationship from the literature with numerical simulations adopting different models are used to determine the transient droplet deformation during transition through orifices. It is shown that numerical and experimental results are in fairly good agreement at limited settings. It can be concluded that a scaled apparatus is well suited to estimate the transient droplet formation up to the outlet of the orifice.

Simulation of Sphere’s Motion Induced by Shock Waves

2012 ◽  
Vol 134 (10) ◽  
Author(s):  
Dan Igra ◽  
Ozer Igra ◽  
Lazhar Houas ◽  
Georges Jourdan
Keyword(s):  
Shock Waves ◽  
Drag Coefficient ◽  
Drag Force ◽  
Stationary Flow ◽  
Experimental Results ◽  
Experimental Findings ◽  
Sphere Drag ◽  
Simulation Scheme ◽  
Good Agreement

Simulations of experimental results appearing in Jourdan et al. (2007, “Drag Coefficient of a Sphere in a Non-Stationary Flow: New Results,”Proc. R. Soc. London, Ser. A, 463, pp. 3323–3345) regarding acceleration of a sphere by the postshock flow were conducted in order to find the contribution of the various parameters affecting the sphere drag force. Based on the good agreement found between present simulations and experimental findings, it is concluded that the proposed simulation scheme could safely be used for evaluating the sphere’s motion in the postshock flow.

Viscoelastic Deformation of PC/ABS Alloy

2007 ◽  
Vol 353-358 ◽  
pp. 1229-1232
Author(s):  
Z.N. Yin ◽  
L.F. Fan ◽  
Tie Jun Wang
Keyword(s):  
Dynamic Mechanical Analysis ◽  
Relaxation Modulus ◽  
Mechanical Analysis ◽  
Experimental Results ◽  
Viscoelastic Deformation ◽  
Dynamic Mechanical ◽  
Storage And Loss Moduli ◽  
Static Relaxation ◽  
Comparison Of The Results ◽  
Good Agreement

Dynamic Mechanical Analysis (DMA) and static relaxation tests are carried out to study the viscoelastic deformation of PC/ABS alloy with blending ratio of PC to ABS being 50/50. A modified approach is developed to calculate the relaxation modulus of PC/ABS alloy from the DMA experimental results of storage and loss moduli. Comparison of the results obtained from DMA and static relaxation tests is presented and good agreement is found.

Influence of the Morphology on the Optical Properties of Nanocermet Films: A Renormalization Approach

1990 ◽  
Vol 195 ◽  
Author(s):  
S. Berthier ◽  
K. Driss-Khodja
Keyword(s):  
Optical Properties ◽  
Critical Exponents ◽  
Inhomogeneous Media ◽  
Experimental Results ◽  
Percolation Transition ◽  
Position Space ◽  
Renormalization Approach ◽  
2D And 3D ◽  
Good Agreement ◽  
Effective Medium Models

ABSTRACTIn order to take into account the actual morphology of the inhomogeneous media, we have developed, effective medium models based on a 2D and 3D position space renormalization /1,2/. These models predict the dipolar resonance and the percolation transition with critical exponents in good agreement with theoretical values and fairly reproduce most of the experimental results, whatever the concentration is. Further more, this allows a valuable comparison of the predictions of our models when applied on different lattices like real digitized TEM of cermet films or randomly occupied lattices.

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