Heat transfer in horizontal tubes immersed in fluidized beds

A theoretical model is proposed, and experimental data presented and analyzed, for the overall convective heat transfer coefficient at ambient conditions between horizontally immersed tubes and a gas fluidized bed of particle sizes usually applicable in fluidized bed combustion of coal. The overall heat transfer coefficient is a function of gas and particle heat transfer coefficients. The bubbling flow assumption, together with the two phase theory of fluidization, is used to obtain a simple analytical solution for the particle convective heat transfer coefficient. The equation for gas convective heat transfer coefficient is obtained through an analogy with heat transfer in packed beds. To a first order approximation the particle and gas convective components are additive.