Heat Transfer from a Tube Immersed in a Fluidized Bed with Frosting

Heat transfer and visualization experiments were performed for a single cooled tube immersed horizontally in a fluidized bed under frosting conditions. Measurements were made of local and average heat transfer coefficients around the cooled tube surface. Glass beads having nominal diameters of 0.43 mm, 0.89 mm and 1.6 mm were employed as bed particles. The 30 mm diameter tube was kept 100 mm above the distributor. All of the results obtained under frosting conditions were for an air temperature of about 5°C and an air relative humidity of about 80%. Heat transfer coefficient with frosting evaluated in the present investigation includes the heat transfer coefficient from the frost surface to the bed and the thermal resistance of the frost layer. Comparisons were made of heat transfer data without frosting. The obtained data were found to be larger than those without frosting under the state of fluidization.