Theoretical Analysis and Models for Heat Transfer

The heat transfer coefficient hc between the suspension and an immersed surface may be considered to be composed of three additive components  

the particle convective transfer component hpc, which represents the heat transfer due to particle motion within the bed  

the gas convective transfer component hgc, which represents the heat transfer to or from the gas percolating through the bed  

the radient transfer component hnd, which represents the radiative heat transfer between FFB and the heat transfer surface. 

The second and the third components become significant only at high temperatures ( 700°C) and low solids concentrations ( 30 kg/m3). In fast fluidized beds, the motion of the particles plays an overriding role in the heat transfer process, since the solids particles have larger heat capacity and higher thermal conductivity. Most of the heat transfer models reported in the literature give emphasis to particle convective transfer. 

---