External heat transfer in polydispersed fluidized beds at elevated temperatures |
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Authors: | V A Borodulya Yu S Teplitskii A P Sorokin V V Matsnev I I Markevich V I Kovenskii |
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Affiliation: | (1) A. V. Lykov ITMO, Academy of Sciences of the Belorussian SSR, Minsk;(2) I. I. Polnzuov NPO TsKTI, Leningrad |
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Abstract: | The authors present results of a theoretical and experimental study of heat transfer in polydispersed fluidized beds of coarse particles at temperatures up to 1273 K.Notation
a
tube radius
- Cf
specific heat of the gas
- di
mean diameter of the i-th fraction
- g
acceleration due to gravity
- H
height of the fluidized bed
- J=fu
mass flow rate of gas
- 0
thickness of the gas film on the heat transfer surface
- m0
porosity at the onset of fluidization
- m
porosity
- r
radius
- R
radius of the equipment
- tf, °C, Tf, °K
gas temperature
- T0
initial gas temperature
- Tt8, Tw
temperature of the fluidized bed and of the heat transfer surface, u, u0, speed of filtration and speed at the start of fluidization
- a
heat-transfer coefficient
- w, b
emissivities of the heat transfer surface, and the fluidized bed
- S
emissivity of the particles
- e
effective (apparent) emissivity of the fluidized bed
- f
viscosity of the gas
- f
thermal conductivity of the gas
- f
0=f0
c+ncfJd2/m
thermal conductivity of the gas at tf=0°C
- f
c
molecular thermal conductivity of the gas
- f
c
at temperature (Tw+Tt8)/2
- f0
c
molecular thermal conductivity of the gas at tf=0°C, =glf/glf0
c
- S, f
density of particles in the gas
-
Stefan-Boltzmann constant
- Ar=gd1fS-f)/f
2
Archimedes Number
- Pe=cfJ0
2/Hmf0
c
Peclet number
- Re=ud1f/f
Reynolds Number
Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 56, No. 5, pp. 767–773, May, 1989. |
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Keywords: | |
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