Heat transfer to walls in a high temperature fluidized bed of group II particles

High temperature heat transfer data in the particle diameter range 0.73 – 1.41 mm and temperature range 490 – 918 °C are presented. The original measurement method is based on an overall thermal balance over a 0.40 m² heat exchange surface. Experimental data are analyzed using results from the literature and a ‘particle-based’ heat transfer model. It is found that gas convective heat transfer is significant for the largest particles (1.41 mm) but it may be neglected for 1.18 mm particles at temperatures above 700 °C. An analysis of this result on the basis of Saxena and Ganzha's powder classification scheme is proposed. A general correlation based on Archimedes and Planck numbers is presented. It takes into account the interaction between radiation and conduction at high temperatures, utilizing the experimental results for beds of corundum particles (0.28, 0.425, 0.6, 0.73, 1, and 1.18 mm) in the temperature range 500 – 900 °C.