Effect of solids circulation on heat transfer from an immersed horizontal rod in a gas fluidized bed
The influence of solids motion on heat transfer to immersed surfaces within fluidized beds has been well established, yet details of the relationship remain unclear. Although some general trends have been observed in the variation of the local heat transfer coefficient around the circumference of an immersed horizontal tube, few attempts have been made toward describing the effect of the gross solids circulation on the values of the heat transfer coefficients for heat exchange surfaces distributed throughout the bed volume. This can be attributed to the inability of previous researchers to measure the solids velocity distribution within the fluidized bed. The present study utilizes a novel particle tracking method to measure mean solids velocities and to observe the effect of solids motion on heat transfer to immersed surfaces within the bed. The gross circulation patterns are presented for monodispersed particles with a mean diameter of 0.50 mm at a fluidizing velocity of 2.5 times the minimum. The variation of the local heat transfer coefficient around the circumference of an immersed horizontal rod was measured at four bed locations and at three fluidizing velocities including 2.5 times the minimum. It was found that the magnitudes of the heat transfer coefficients were greatly influenced by the direction of solids flow. The coefficients were highest at those locations where solids impact was greatest.
- Research Organization:
- Illinois Univ., Urbana (USA). Dept. of Mechanical Engineering
- DOE Contract Number:
- FG22-81PC40804
- OSTI ID:
- 6401079
- Report Number(s):
- DOE/PC/40804-T15; ON: DE86003646
- Country of Publication:
- United States
- Language:
- English
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CARBONACEOUS MATERIALS
CHEMICAL REACTIONS
COAL
COMBUSTION
ENERGY SOURCES
ENERGY TRANSFER
FLUIDIZATION
FLUIDIZED BEDS
FLUIDIZED-BED COMBUSTION
FOSSIL FUELS
FUELS
HEAT TRANSFER
MATERIALS
OXIDATION
PARTICLE TRACKS
PARTICLES
PARTICULATES
THERMOCHEMICAL PROCESSES
VELOCITY