Hydrodynamics of Pulse-Stabilized Fluidization at Incipient Fluidization

1999 ◽  
Author(s):  
Subhadeep Gan ◽  
Donald E. Beasley
Keyword(s):  
Pressure Drop ◽  
Secondary Flow ◽  
Fluidized Bed ◽  
Flow Rate ◽  
Test Section ◽  
Video Recording ◽  
Small Displacement ◽  
Pulsation Frequency ◽  
Primary Flow ◽  
Oscillatory Component

Abstract A laboratory scale experimental facility which models a Pulsed Atmospheric Fluidized Bed Combustor (PAFBC) has been developed; this facility is designed to examine the effect of an opposing secondary flow having an oscillatory component on a bubbling fluidized bed. The secondary flow is oriented in a vertical direction. The secondary flow is introduced into the bubbling bed through a tailpipe that extends through the bed and ends just above the porous polyethylene distributor. A pulsed flow simulator that employs a small displacement of a relatively large piston with variable drive radius and speed provides the oscillatory component of the secondary flow. The fluidized bed test section has a cross-sectional flow area of 30.5 by 30.5 cm with a height of 53 cm. Heat exchanger surfaces are modeled by two symmetric horizontal cylinders housed in the test section. The following test parameters are controlled: the primary flow rate, the mean secondary flow rate, the pulsation frequency and the amplitude of the secondary flow. Pressure taps are located just above the distributor and in the freeboard region to measure overall bed pressure drop. The facility is operated with a range of particles from 345 μm to 715 μm and a range of superficial fluidization velocities corresponding to the bubble flow regime. Fluidization curves were generated for traditional fluidization, using the primary flow through the porous distributor, with both primary and a steady secondary flow, and with primary and a pulsed secondary flow. Significant departures from the linear Darcy flow curves in the fixed bed region were observed, and attributed to significant local fluidization. Time resolved measurements of the overall bed pressure drop clearly indicate phase-locking behavior of the overall bed pressure drop with imposed frequency. Bubbles formed in pulse-stabilized fluidization are significantly smaller than in traditional fluidization, as observed through video recording of the present bed.

Does the Minimum Fluidization Exist?

2002 ◽  
Vol 124 (3) ◽  
pp. 595-600 ◽  
Author(s):  
Arnaud Delebarre
Keyword(s):  
Porous Medium ◽  
Pressure Drop ◽  
Fluidized Bed ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Granular Bed ◽  
Minimum Fluidization ◽  
Fluid Characteristics

This work proposes an equation giving the pressure drop of a gas flowing through a porous medium or a granular bed. The consequences for the onset of the fluidization are then discussed. It appears that the notion of minimum gas mass-flow rate would improve the description of the transition between fixed and fluidized bed regimes. An equation is then proposed to calculate the minimum fluidization gas mass-flow rate. It is then proved that the minimum fluidization is not only a function of the medium and fluid characteristics but also that it increases with bed inventory. It is then shown that a batch of particles has a minimum fluidization depending on its arrangement in a column and that in some cases, this minimum does not exist at all. As a consequence, the minimum of fluidization, whether it is a velocity or a mass flow rate, cannot be considered as a criterion to characterize a powder.

scholarly journals Influence of CFD Analysis on the Design of Cooling Channels for the CCL Cavity for the Spallation Neutron Source

2000 ◽  
Author(s):  
Snezana Konecni ◽  
Nathan K. Bultman
Keyword(s):  
Pressure Drop ◽  
Flow Rate ◽  
Test Section ◽  
Cooling System ◽  
Flow Loop ◽  
Pressure Transducers ◽  
Cooling Channels ◽  
Recorded Data ◽  
Computational Fluid Dynamics Cfd ◽  
Turbine Flow Meter

Abstract Water flow in cooling channels was simulated using the computational fluid dynamics (CFD) code CFX4. Pressure drop in the cooling channels of the coupled-cavity linac (CCL) cavity was calculated. The effects of the manifold on the pressure drop were studied also. Reducing the pressure drop was a primary goal of this exercise that led to changing the cooling channel entrance regions. Results of this analysis were used in sizing pumps required for the cooling system. For the validation of the simplified numerical model, an experiment was performed to measure the pressure drop in the cooling channels for variable flow rate, using a flow loop. Deionized water was circulated through the test section with a pump and its flow rate was monitored with a turbine flow meter. Pressure was monitored with pressure transducers at five locations including a differential pressure transducer across the test section, and water temperature was taken at the exit of the pump. Pressure drop across the inlet and outlet of the test section was measured and recorded for different flow rates. Flow rate was also monitored and stored simultaneously. From the recorded data, an empirical correlation was derived to describe the pressure drop, dp, as a function of flow rate through the four cooling channels.

scholarly journals Absorption in a three-phase fluidized bed I: Hydrodynamic investigations

2003 ◽  
Vol 57 (7-8) ◽  
pp. 326-329 ◽  
Author(s):  
Srdjan Pejanovic
Keyword(s):  
Mass Transfer ◽  
Pressure Drop ◽  
Fluidized Bed ◽  
Flow Rate ◽  
Gas Flow ◽  
Minimum Fluidization Velocity ◽  
Bed Height ◽  
Three Phase ◽  
Height Increase ◽  
Improve Mass Transfer

The hydrodynamic properties of a three phase fluidized bed with low density inert spherical packing, fluidized by the interaction of a gas flowing upwards and a liquid flowing downwards through the column, were investigated. It was found that the pressure drop, liquid hold up and dynamic bed height increase with both increasing liquid and gas flow rate. While the dynamic bed height and minimum fluidization velocity remain unchanged, both the pressure drop and liquid hold up increase with increasing density of the packing. Therefore, an increase in packing density causes more intensive mass transfer between the fluid phases than packed columns. It was shown that increase of the liquid flow rate causes an increase of both the effective liquid and gas velocity through the fluidized bed, which may also improve mass transfer.

CFD-Analysis of Single Rectangular Microchannel Under Forced Convection Heat Transfer Condition for Laminar Flow

2013 ◽  
Author(s):  
D. A. Kamble ◽  
B. S. Gawali
Keyword(s):  
Pressure Drop ◽  
Laminar Flow ◽  
Flow Rate ◽  
Temperature Rise ◽  
Heat Input ◽  
Test Section ◽  
Hydraulic Diameter ◽  
Cfd Analysis ◽  
Rectangular Microchannel ◽  
Computational Fluid Dynamics Analysis

This paper describes the CFD analysis of single rectangular microchannel for hydraulic diameter 319 μm. While CFD analysis the Nusselt number observed is 4 to 5 with different Reynolds Number variation for flow rate of 0.001 kg/sec to 0.012 kg/sec. The current work describes CFD analysis of single microchannels for length of 50 mm with water as a fluid medium with laminar flow. Computational Fluid dynamics analysis of Single rectangular microchannel Single rectangular microchannel of 319 μm hydraulic diameter is analyzed to study the flow characteristics in the inlet, microchannel test section and outlet test section with ANSYS CFX-11 for pressure drop, temperature drop, velocity counter of single micro-channel. For analyzing the weather the turbulence is created at inlet part of the microchannel a pressure drop analysis is carried for flow rate of 0.012 kg/sec with heat input 5.33 watt/cm2 under laminar flow consideration. For analyzing the temperature profile across microchannel a for flow rate of 0.012 kg/sec with heat input 5.33 watt/cm2 under laminar flow is considered.. For single microchannel the temperature rise of water is in range of 1 °K to 2 °K at center plane of microchannel. It is found that at leading edges or leaving edge the temperature rise in water is higher as compare to entering edge of microchannel. It is due to while entering to leaving of water particles in microchannel it collapse each other and try to increasing friction along each other so at outlet or leading edge the temperature rise is seen higher as compare to in let portion of single microchannel.

Relationship between Solid Flow Rate and Pressure Drop in the Riser of a Pressurized Circulating Fluidized Bed

2016 ◽  
Vol 49 (7) ◽  
pp. 595-601 ◽  
Author(s):  
Muhammad Shahzad Khurram ◽  
Jeong-Hoo Choi ◽  
Yoo Sube Won ◽  
A-Reum Jeong ◽  
Ho-Jung Ryu
Keyword(s):  
Pressure Drop ◽  
Fluidized Bed ◽  
Flow Rate ◽  
Circulating Fluidized Bed ◽  
Solid Flow

Utilization of Waste of Enzymes Biomass as Biosorbent for the Removal of Dyes from Aqueous Solution in Batch and Fluidized Bed Column

2020 ◽  
Vol 71 (1) ◽  
pp. 1-12
Author(s):  
Salman H. Abbas ◽  
Younis M. Younis ◽  
Mohammed K. Hussain ◽  
Firas Hashim Kamar ◽  
Gheorghe Nechifor ◽  
...  
Keyword(s):  
Experimental Data ◽  
Aqueous Solution ◽  
Particle Size ◽  
Adsorption Capacity ◽  
Fluidized Bed ◽  
Flow Rate ◽  
Fungal Biomass ◽  
Solution Flow Rate ◽  
Maximum Adsorption Capacity ◽  
Solution Flow

The biosorption performance of both batch and liquid-solid fluidized bed operations of dead fungal biomass type (Agaricusbisporus ) for removal of methylene blue from aqueous solution was investigated. In batch system, the adsorption capacity and removal efficiency of dead fungal biomass were evaluated. In fluidized bed system, the experiments were conducted to study the effects of important parameters such as particle size (701-1400�m), initial dye concentration(10-100 mg/L), bed depth (5-15 cm) and solution flow rate (5-20 ml/min) on breakthrough curves. In batch method, the experimental data was modeled using several models (Langmuir,Freundlich, Temkin and Dubinin-Radushkviechmodels) to study equilibrium isotherms, the experimental data followed Langmuir model and the results showed that the maximum adsorption capacity obtained was (28.90, 24.15, 21.23 mg/g) at mean particle size (0.786, 0.935, 1.280 mm) respectively. In Fluidized-bed method, the results show that the total ion uptake and the overall capacity will be decreased with increasing flow rate and increased with increasing initial concentrations, bed depth and decreasing particle size.

Study of fluid flow through a channel deformed by piezoelement

2018 ◽  
Vol 13 (3) ◽  
pp. 1-10 ◽  
Author(s):  
I.Sh. Nasibullayev ◽  
E.Sh Nasibullaeva ◽  
O.V. Darintsev
Keyword(s):  
Fluid Flow ◽  
Pressure Drop ◽  
Boundary Conditions ◽  
Flow Rate ◽  
Contact Surface ◽  
Piezoelectric Element ◽  
Neumann Boundary ◽  
Differential Pressure ◽  
Physical Parameters ◽  
Flow Through

The flow of a liquid through a tube deformed by a piezoelectric cell under a harmonic law is studied in this paper. Linear deformations are compared for the Dirichlet and Neumann boundary conditions on the contact surface of the tube and piezoelectric element. The flow of fluid through a deformed channel for two flow regimes is investigated: in a tube with one closed end due to deformation of the tube; for a tube with two open ends due to deformation of the tube and the differential pressure applied to the channel. The flow rate of the liquid is calculated as a function of the frequency of the deformations, the pressure drop and the physical parameters of the liquid.

Pressure Drop Measurements for Air Flow Through Open-Cell Aluminum Foam

2004 ◽  
Author(s):  
Nihad Dukhan ◽  
Angel Alvarez
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Flow Rate ◽  
Aluminum Foam ◽  
Flow Direction ◽  
The Other ◽  
Turbulent Regime ◽  
Thick Sample ◽  
Open Cell ◽  
Two Samples

Wind-tunnel pressure drop measurements for airflow through two samples of forty-pore-per-inch commercially available open-cell aluminum foam were undertaken. Each sample’s cross-sectional area perpendicular to the flow direction measured 10.16 cm by 24.13 cm. The thickness in the flow direction was 10.16 cm for one sample and 5.08 cm for the other. The flow rate ranged from 0.016 to 0.101 m3/s for the thick sample and from 0.025 to 0.134 m3/s for the other. The data were all in the fully turbulent regime. The pressure drop for both samples increased with increasing flow rate and followed a quadratic behavior. The permeability and the inertia coefficient showed some scatter with average values of 4.6 × 10−8 m2 and 2.9 × 10−8 m2, and 0.086 and 0.066 for the thick and the thin samples, respectively. The friction factor decayed with the Reynolds number and was weakly dependent on the Reynolds number for Reynolds number greater than 35.

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