Heat Transfer Coefficient for a Packed Bed of Shredded Materials at Low Peclet Numbers

Abstract

The application of the Nusselt number (Nu) correlation of a packed bed of spherical particles overestimates the rate of heat transfer in the packed beds of shredded materials. This is due to the dependence of flow distribution on the particle geometry. This discrepancy is even more pronounced due to a channeling effect at low Peclet numbers (Pe). In this study, the heat transfer coefficient for a packed bed of shredded materials was derived at low Peclet numbers. In deriving the correlation, both numerical simulation and experimental work were employed. The experimental work was carried out in a packed bed of combustible materials for the flow rates of 15 × 10− 6 to 50 × 10− 6 m 3/s and a temperature range of 30 to 60°C. Using the results of experimental work along with numerical modeling and applying a power law formulation, the best-fit Nusselt number for the packed bed of shredded materials for Pe < 25 was derived to be Nu = 0.015 0.11 + Pe 0.73 . The Nusselt number calculated from this correlation is in good agreement with the experimental data.