Heat transfer characteristics between the immersed heater and the bed content were studied in the riser of a liquid-solid circulating fluidized bed

whose diameter and height were 0.102 m (ID) and 2.5 m

respectively. Effects of liquid velocity

particle size

surface tension of liquid phase and solid circulation rate on the overall heat transfer coefficient were examined. The heat transfer coefficient increased with increasing particle size or solid circulation rate due to the higher potential of particles to contact with the heater surface and promote turbulence near the heater surface. The value of heat transfer coefficient increased gradually with increase in the surface tension of liquid phase

due to the slight increase of solid holdup. The heat transfer coefficient increased with the liquid velocity even in the higher range

due to the solid circulation prevented the decrease in solid holdup

in contrast to that in the conventional liquid-solid fluidized beds. The values of heat transfer coefficient were well correlated in terms of dimensionless groups as well as operating variables.