Heat transfer from immersed vertical cylinders in gas-liquid and gas-liquid-solid fluidized beds

The heat transfer coefficient, h, was measured using a cylindrical heater vertically immersed in liquid-solid and gas-liquid-solid fluidized beds. The gas used was air and the liquids used were water and 0.7 and 1.5 wt-% carboxymethylcellulose (CMC) aqueous solutions. The fluidized particles were sieved glass beads with 0.25, 0.5, 1.1, 2.6, and 5.2 mm average diameters. We tried to obtain unified dimensionless correlations for the cylinder surface-to-liquid heat transfer coefficients in the liquid-solid and gas-liquid-solid fluidized beds. In the first approach, the heat transfer coefficients were successfully correlated in a unified formula in terms of a modified j(11)-factor and the modified liquid Reynolds number considering the effect of spatial expansion for the fluidized bed within an error of 36.1%. In the second approach, the heat transfer coefficients were also correlated in a unified formula in terms oft he dimensionless quantities, Nu/Pr-1/3 and the specific power group including energy dissipation rate per unit mass of liquid, (ED4/3)-D-1/3/v(1), within a smaller error of 24.7%. It is also confirmed that a good analog exists between the surface-to-liquid heat transfer and mass transfer on the immersed cylinder in the liquid-solid and gas-liquid-solid fluidization systems.