Bed-surface contact dynamics for horizontal tubes in fluidized beds

AIChE Journal ◽  
1982 ◽  
Vol 28 (6) ◽  
pp. 907-914 ◽  
Author(s):  
Ravi Chandran ◽  
J. C. Chen
Keyword(s):  
Fluidized Beds ◽  
Contact Dynamics ◽  
Horizontal Tubes ◽  
Surface Contact

Local Heat Transfer Coefficients around Horizontal Tubes in Fluidized Beds

1980 ◽  
Vol 102 (1) ◽  
pp. 152-157 ◽  
Author(s):  
R. Chandran ◽  
J. C. Chen ◽  
F. W. Staub
Keyword(s):  
Heat Transfer ◽  
Particle Size ◽  
Fluidized Beds ◽  
Local Heat Transfer ◽  
Local Heat ◽  
General Tendency ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Horizontal Tubes ◽  
System Pressure

The local characteristics of heat transfer from horizontal tubes immersed in fluidized beds were investigated experimentally. Steady-state heat transfer measurements were obtained in air-fluidized beds of glass beads, both for a single tube and a ten-row bare tube bundle. The test results indicated that local heat transfer coefficients are strongly influenced by angular position and gas flow rate, as well as by particle size and system pressure. The heat transfer coefficients, averaged around the circumference of the tube, exhibited a general tendency to increase with decreasing particle size and increasing system pressure. The heat transfer coefficients for a tube in an inner-row position within the bundle were found to be slightly higher than those for a tube in the bottom-row. Comparison of the average heat transfer coefficient data obtained in this study with some of the existing correlations for heat transfer from horizontal tubes showed that the correlations are unsatisfactory.

Numerical Study of Bubbling Gas-Solid Fluidized Beds Hydrodynamics: Influence of Immersed Horizontal Tubes and Data Analysis

2011 ◽  
Vol 9 (1) ◽  
Author(s):  
Teklay W. Asegehegn ◽  
Matthias Schreiber ◽  
Hans J. Krautz
Keyword(s):  
Fluidized Beds ◽  
Numerical Study ◽  
Fluid Model ◽  
Vertical Direction ◽  
Expansion Ratio ◽  
Solid Particles ◽  
Superficial Velocity ◽  
Tube Bank ◽  
Horizontal Tubes ◽  
Two Fluid Model

Numerical simulations of two dimensional gas-solid bubbling fluidized beds with and without immersed horizontal tubes were performed using Eulerian - Eulerian Two Fluid Model (TFM). The influences of immersed horizontal tubes and different data analyses techniques on the bed and bubble hydrodynamics were investigated. The results were compared with experimental data and correlations available in the literature.Different ways for extracting and defining hydrodynamic properties, such as bed expansion ratio and bubble properties, were found to influence the simulation results. Furthermore, the time-averaged values showed greater sensitivity to the length of averaging time in the first few seconds. With regard to tube influence, immersed tubes were found to be the main source of bubble breakup. Thus, the calculated mean bubble diameters and rise velocities were found to be lower with tubes than without for the same bed geometry and superficial velocity. The bubble shapes were observed to elongate in the vertical direction in the tube bank region compared to the bed region below and above the tube bank. In addition, the TFM was found to successfully predict the overall time-averaged solid motion and distribution. For beds with immersed tubes, defluidized regions were observed at the upper part of the tubes where solid particles rested without moving. On the other hand, the lower parts of the tubes were usually covered with gas pockets. These effects were seen to reduce with increasing superficial velocity.

Particle contact dynamics on tubes in the freeboard region of fluidized beds

AIChE Journal ◽  
1987 ◽  
Vol 33 (7) ◽  
pp. 1225-1227 ◽  
Author(s):  
S. Biyikli ◽  
K. Tuzla ◽  
J. C. Chen
Keyword(s):  
Fluidized Beds ◽  
Contact Dynamics ◽  
Particle Contact

Modelling of finger-surface contact dynamics

2014 ◽  
Vol 74 ◽  
pp. 130-137 ◽  
Author(s):  
Ramona Fagiani ◽  
Marco Barbieri
Keyword(s):  
Contact Dynamics ◽  
Surface Contact
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