THE EFFECTS OF INTER-PARTICLE FORCE ON HEAT TRANSFER AROUND HORIZONTAL TUBE IN A FLUIDIZED BED
Effects of cohesiveness and subsequent agglomeration of particles on the heat transfer characteristics around the horizontal tube immersed in a bubbling fluidized bed were experimentally investigated. The inter-particle cohesive forces due to a liquid bridge were controlled by changing the humidity of the fluidizing air. The gross behavior of the fluidization of the cohesive particles was quantitatively studied by measuring the bed pressure drop and by visual observation. The instantaneous heat transfer coefficient and particle behavior were simultaneously measured at the same location on the tube surface. When the inter-particle forces increased as the relative humidity of the fluidizing air increased, the void fraction around the tube became higher and the movements of the particles on the upper surface of the tube were suppressed, and consequently, the heat transfer coefficient around the tube became significantly lower.