Fluidization hydrodynamics are greatly influenced by inter-particle cohesive forces. This paper studies the fluidization of large cohesive particles in a two-dimensional fluidized bed with immersed tubes using “polym...Fluidization hydrodynamics are greatly influenced by inter-particle cohesive forces. This paper studies the fluidization of large cohesive particles in a two-dimensional fluidized bed with immersed tubes using “polymer coating” to introduce cohesive force, to gain better understanding of bubbling behavior when particles become cohesive and its effect on chemical processes. The results show that the cohesive force promotes bubble splitting in the tube bank region, thereby causing an increase in the number and a decline in the aspect ratio of the bubbles. As the cohesive force increases within a low level, the bubble number increases and the bubble diameter decreases, while the aspect ratio exhibits different trends at different fluidization gas velocities. The difference in the evolution of bubble size under various cohesive forces mainly takes place in the region without tubes. When the cohesive force is large enough to generate stable agglomerates on the side walls of the bed, the bubble number and the bed expansion sharply decrease. The tubes serve as a framework that promotes the agglomeration, thus accelerating defluidization. Finally, the bubble profile around tubes was studied and found to greatly depend both on the cohesive forces and the location of tubes.展开更多
Heat transfer coefficients for horizontally immersed tubes have been studied in a model of ICFB (Internally Circulating Fluidized Bed). The characteristics in ICFB were found to be significantly differentfrom those in...Heat transfer coefficients for horizontally immersed tubes have been studied in a model of ICFB (Internally Circulating Fluidized Bed). The characteristics in ICFB were found to be significantly differentfrom those in bubbling bed. There is a flowing zone with high velocity in the heat exchange zone.The heat transfer coefficients strongly depend on the fluidized velocity in the flowing zone. The heatexchange process and suitable bed temperature can be controlled according to this feature. Based onthe results of the experiments, a formulation for heat transfer has been developed.展开更多
基金Financial support of this work by the National Nature Science Foundation of China （Grant numbers 51306035 and 51676042） and Scientific Research Foundation of the Graduate School of Southeast University are gratefully acknowledged.
文摘Fluidization hydrodynamics are greatly influenced by inter-particle cohesive forces. This paper studies the fluidization of large cohesive particles in a two-dimensional fluidized bed with immersed tubes using “polymer coating” to introduce cohesive force, to gain better understanding of bubbling behavior when particles become cohesive and its effect on chemical processes. The results show that the cohesive force promotes bubble splitting in the tube bank region, thereby causing an increase in the number and a decline in the aspect ratio of the bubbles. As the cohesive force increases within a low level, the bubble number increases and the bubble diameter decreases, while the aspect ratio exhibits different trends at different fluidization gas velocities. The difference in the evolution of bubble size under various cohesive forces mainly takes place in the region without tubes. When the cohesive force is large enough to generate stable agglomerates on the side walls of the bed, the bubble number and the bed expansion sharply decrease. The tubes serve as a framework that promotes the agglomeration, thus accelerating defluidization. Finally, the bubble profile around tubes was studied and found to greatly depend both on the cohesive forces and the location of tubes.
文摘Heat transfer coefficients for horizontally immersed tubes have been studied in a model of ICFB (Internally Circulating Fluidized Bed). The characteristics in ICFB were found to be significantly differentfrom those in bubbling bed. There is a flowing zone with high velocity in the heat exchange zone.The heat transfer coefficients strongly depend on the fluidized velocity in the flowing zone. The heatexchange process and suitable bed temperature can be controlled according to this feature. Based onthe results of the experiments, a formulation for heat transfer has been developed.
