Abstract: | A method is proposed for the joint determination of the coefficients of horizontal particle diffusion and external heat exchange in a stagnant fluidized bed.Notation cf, cs, cn
specific heat capacities of gas, particles, and nozzle material, respectively, at constant pressure
- D
effective coefficient of particle diffusion horizontally (coefficient of horizontal thermal diffusivity of the bed)
- d
equivalent particle diameter
- dt
tube diameter
- H0, H
heights of bed at gas filtration velocities u0 and u, respectively
- Ha
height of active section
-
l
width of bed
- L
tube length
-
l
o
width of heating chamber
- N
number of partition intervals
- p=H/H0
expansion of bed
- sn
surface area of nozzle per unit volume of bed
- Sh, Sv
horizontal and vertical spacings between tubes
- tc, t0, ts, tn, tw
initial temperature of heating chamber, entrance temperature of gas, particle temperature, nozzle temperature, and temperature of apparatus walls, respectively
- u0, u
velocity of start of fluidization and gas filtration velocity
- y
horizontal coordinate
-
*,
coefficient of external heat exchange between bed and walls of apparatus and nozzle
- 1, 1, 2, ...
coefficients in (4)
-
thickness of tube wall
- b
bubble concentration in bed
- 0
porosity of emulsion phase of bed
- n
porosity of nozzle
- =(ts – t0)/(tc – t0)
dimensionless relative temperature of particles
- n
coefficient of thermal conductivity of nozzle material
- f, s, n
densities of gas, particles, and nozzle material, respectively
- be=s(1 – 0) (1 – b)
average density of bed
-
time
- max
time of onset of temperature maximum at a selected point of the bed
- R =l
o/l
Fourier number
- Pe = 1
l
2/D
Péclet number
- Bi = /n
Biot number
Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 41, No. 3, pp. 457–464, September, 1981. |