Temperature Distribution Near a Heat Exchanger Wall Immersed in High-Temperature Packed and Fluidized Beds

Abstract

Experimental results dealing with both particle and gas temperature distribution in the vicinity of a water-cooled wall immersed in fixed and fluidized beds are presented. The measurement of particle temperature is based on the use of a mobile optical fiber connected to a two-color radiometer. The gas temperature is obtained on the basis of the indications of a bare thermocouple. Particle and gas temperature fields are compared in fixed and fluidized beds for alumina and silicon carbide particles. In the fixed bed, temperature differences as large as 300°C between the gas and the solid are measured. In the fluidized bed, temperature decreases of both solid and gas phase are shown for large particle at incipient fluidization. The temperature variation reaches more than 100°C for corundum particles and 200°C in the gas. The temperature distribution in the solid phase is shown to be dependent on the thermophysical properties of the particles (thermal conductivity and emissivity).