SINOPSIS

A mathematical model for description of heat transfer under Circulating Fluidized Bed (CFB)-conditions is proposed. According to the dominating heat transfer mechanisms (particle convection and particle radiation) the model is based on two modules describing the radiative and convective part. The shielding effect of the dense and cool wall layer is included and demonstrated. Due to the variation of particles concentration in the wall layer the radiation behaviour changes between optical thin and optical thick. The development of a wall layer close to the wall and platen heat exchangers in CFB's was investigated in an experimental way. In a further step bed to wall heat transfer coefficients were measured and are compared to data from literature.