1990 Volume 76 Issue 6 Pages 848-855
For heat transfer between particles and fluid stream in industrial moving beds like as blast furnace and shaft furnace for direct reduction, the significant discrepancy has been reported between actual heat transfer rate and that estimated by empirical correlations.
Three modes of steady-state heat transfer experiments have been carried out between nitrogen stream and hematite pellets in a laboratory scale counter-current moving bed reactor. Longitudinal distribution of both pellet and gas temperatures were measured by sheathed thermocouples inserted at the center of the pellet and protruded from inner wall by 5 mm, respectively. In the measurements, thermal gradient was not found within the pellet because of Bi<0.15 where Bi is Biot number. Heat loss through the wall of the bed was also measured by a heat flow meter.
The observed results have been correlated in terms of Nusselt, Reynolds and Prandtl numbers to give :
Nu= 2.0 + 0.39 Pr1/3Rep1/2 (150<Rep<400)
The coefficient 0.39 obtained here is considerably small compared with those of reported correlations.
