HEAT TRANSFER IN A FLUIDIZED SOLIDS BED

1950 ◽  
Vol 28f (8) ◽  
pp. 287-307 ◽  
Author(s):  
J. Klassen ◽  
P. E. Gishler ◽  
A. Baerg
Keyword(s):  
Heat Transfer ◽  
Particle Size ◽  
Bulk Density ◽  
Particle Shape ◽  
Air Flow ◽  
Transfer Coefficients ◽  
Air Velocity ◽  
Heat Transfer Coefficients ◽  
Minimum Fluidizing Velocity

Heat transfer coefficients have been determined in a fluidized solids bed under a wide variety of conditions. The variables studied were particle size, bulk density under nonfluidized conditions, particle shape, and air velocity. Simple correlations have been established predicting the value of h in the air flow range investigated. An equation predicting the minimum fluidizing velocity has also been derived.

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.

scholarly journals EXPERIMENTAL STUDY ON BED-TO-TUBE HEAT TRANSFER COEFFICIENTS IN BUBBLING FLUIDIZED BED

2021 ◽  
Vol 15 (2) ◽  
pp. 139-149
Author(s):  
Bamiji Zacheous Adewole
Keyword(s):  
Heat Transfer ◽  
Particle Size ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Fluidized Bed ◽  
Particle Sizes ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Bubbling Fluidized Bed ◽  
Coconut Shells

The overall bed-to-tube heat transfer coefficients of the blends of Lafia-obi coal and coconut shells have been investigated in a bubbling fluidized bed combustor. Experiments were performed at five different particle sizes of coal (5, 10, 15, 20 and 25 mm) and five different particle sizes of coconut shells (2, 6, 10,14 and 18 mm) for different blend proportions of 10%, 20%, 30%, 40% and 50%. Results obtained showed that the overall bed-to-tube heat transfer coefficient decreased with increasing coconut shell particle size in the blends. Combined effects of high radiation from large particle size of coal (25 mm) and high convection heat from small particle size of coconut shell (2 mm) at blend proportion of 10 and 50% produced the maximum bed-to-tube heat transfer coefficient. Due to the importance of heat exchange in the fluidized bed, it is observed that the contribution of biomass co-firing with coal is significant, hence, co-firing at optimal particle size and biomass blend ratio is imperative for achieving higher bed-to-tube heat transfer in the fluidized bed boiler.

Measurements of Heat Transfer and Pressure Drop for an Array of Staggered Plates Aligned Parallel to an Air Flow

1980 ◽  
Vol 102 (3) ◽  
pp. 426-432 ◽  
Author(s):  
E. M. Sparrow ◽  
A. Hajiloo
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Reynolds Number ◽  
Pressure Drop ◽  
Air Flow ◽  
Plate Thickness ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Naphthalene Sublimation Technique ◽  
Naphthalene Sublimation

The heat transfer and pressure drop characteristics of an array of staggered plates, aligned parallel to the direction of a forced convection air flow, have been studied experimentally. During the course of the experiments, the plate thickness and Reynolds number were varied parametrically. Mass transfer measurements employing the naphthalene sublimation technique were made to obtain the heat transfer results via the heat-mass transfer analogy. For a given operating condition, the per-plate heat transfer coefficients were found to be the same for the second and all subsequent rows. The fully developed heat transfer coefficients increase with Reynolds number for all the plate thicknesses investigated, but in a different manner for the different thicknesses. In general, thicker plates give rise to higher heat transfer coefficients, especially at the larger Reynolds numbers. The measured friction factors also increase with plate thickness. For the thickest plates, the friction factor was found to be independent of the Reynolds number, signalling the dominance of inertial losses.

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