The characteristics of heat transfer and hydrodynamics in two (liquid-solid), three (liquid-gas-solid) phase fluidized bed and three phase fluidized beds of floating contactors have been investigated in a 15.2 cm ID column fitted with an axially mounted cylindrical heater.
Glass beads of 1.7 mm particles were fluidized by the upflow of tap water as the continuous phase and air as the dispersed bubble phase under the bubble coalescing regime.
Effects of the liquid and gas velocity, the volume ratio of floating contactors to particles, the shape and density of floating contactors on the heat transfer coefficients have been examined.
In the bubble coalescing regime, the heat transfer coefficient in three phase fluidized beds was enhanced by the addition of floating contactors. The addition of 10-15% floating contactors produced a maximum increases in heat transfer coefficient of 5-15% in comparison to that in the bed without floating contactors. Also the gas phase holdup which is inversely proportional to the bubble size exhibited the maximum values around the optimum volume ratio of floating contactors to particles.
The shape and density of floating contactors had great influence on the heat transfer coefficients. The floating contactors having higher value of sphericity and similar density to the that of bed exhibited the higher values of heat transfer coefficients.
The increase of heat transfer coefficient by the addition of floating contactors was explained by the liquid turbulence due to their motion as well as their bubble breaking effect.
Heat transfer coefficients in three phase fluidized beds of floating contactors were correlated with the experimental variables as;
$Nu=0.117Re^{.444}\cdot[(V_{fc}+V_s)/V_s]^{.783}\cdot\phi_s^{2.115}\cdot \mid (\rho_f-\rho_b)/\rho_s^{-0.2}\mid$
