Experimental and numerical investigation of heat transfer characteristics in an internally circulating fluidized bed

The heat transfer performance of a tube heat exchanger has great significance for the metal smelting, catalytic cracking and combustion performance in the fluidized bed reactor. In this paper, a three dimensional Eulerian-Eulerian simulation for the vertical heater tube to bed heat transfer within a baffle type internal circulating fluidized bed (ICFB) was conducted numerically and the results were compared to experimental ones. Gidaspow's drag correlation was adopted to describe the interaction between the gas and solid phases in the ICFB. Temperature and heat transfer coefficient were numerically analyzed under different operating conditions as same as the experimental setup. The effects on the heat transfer characteristic of input heat flux, air inlet velocity, and initial solid packing height were investigated as the average temperature was compared with the experimental data in the literature. The simulation results showed that along the height of the bed, the velocity of the solid particles increases, lateral movement of the particles from the low-speed area to the high-speed area can be observed at the bottom of the acceleration area. The convective heat transfer coefficient of solid particles is the main component of heat transfer in the dense phase zone, with the increase of the initial solid packing height, the average convection heat transfer coefficient between the fluid and the heated surface is shown an upward trend. By comparing the experimental datas, it can be concluded that the numerical simulation of the flow and heat transfer process of the inner circulating fluidized bed by the Eulerian-Eulerian method is in good agreement with the experimental results.