Heat transfer coefficient at minimum fluidization velocity for gas-solid fluidized beds
A semi-empirical correlation for heat transfer coefficients between dense gas-solid quiescent fluidized beds and surfaces is presented. Surface heat transfer coefficients at the minimum fluidization condition were measured using a local heat transfer probe in a 5 cm x 30 cm transparent walled, fluidized bed. The initial bed height was held constant at 17.0 cm in all cases. The powders tested were glass, sand, graphite, polypropylene and aluminum with sizes in the range from 25 {micro}m to 1789 {micro}m. The fluidizing medium used was air with the bed operated at atmospheric temperature and pressure. Two different distributor plates were utilized during the experiments, i.e., sintered and perforated distributor plate. Time average, local heat transfer coefficients acquired were averaged over repeated measurements at different times. An empirical correlation for the surface heat transfer coefficient at minimum fluidization conditions, was provided by regressing the 16 data points: Nu = 1.666 Pe{sup 0.553}, for 0.01 {lt} Pe {lt} 100, where the Nusselt number, Nu = (h{sub bs} d{sub p}/k{sub g}) and the Peclet number, Pe = (U{sub mf} d{sub p}/{alpha}{sub g}). The Peclet number effects are accounted for in the equations for heat transfer with diffusion and convection. The resulting expression from the energy balance equation is: Nu = ({radical} Pe/{pi}).
- Research Organization:
- George Mason Univ., Fairfax, VA (US)
- OSTI ID:
- 20002669
- Report Number(s):
- CONF-990805--
- Country of Publication:
- United States
- Language:
- English
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