Heat Transfer in Segregated Fluidized Beds Part 1: Relation between Particle and Temperature Segregation and Dominating Heat Transfer Mechanisms

Abstract

In this paper, segregation characteristics of fluidized particles, which were the mixture of two kinds of grains having different densities and sizes, and the temperature distributions within them were experimentally examined. The dominating heat transfer mechanism was discussed from the experimental results, in order to obtain fundamental information applicable for controlling the particle segregation and/or heat transfer in practical fluidized beds. The experimental results showed that the temperature segregation was dependent on the particle segregation and that the vertical heat transfer in the segregated fluidized bed was greatly resisted by the interface layer, which was located between the jetsam and flotsam layers and had a vertically changing particle concentration. The average vertical heat transfer coefficient or apparent thermal conductivity of the interface layer increased with the excess gas velocity. When the temperature segregation occurs, the apparent thermal conductivity of the interface layer was not only much lower than that of the vigorously fluidized flotsam layer, but even lower than that of the stagnant jetsam layer.

Keywords

• multi-component fluidized bed
• particle segregation
• temperature segregation
• heat transfer
• thermal conductivity