Bubble size distribution in two-dimensional gas-solid fluidized beds

In this article , the digital image analysis (DIA) technique has been used to study the bubble size and bubble size distrubution evolution in a pseudo-two-dimensional gas-solid fluidized bed. In addition, a numerical discrete bubble model (DBM) based on the bubble-bubble interactions was developed and the model predictions were compared with the experimental data. The developed model can predict the bubble size and bubble size distribution through the bed height and the lateral distribution of bubbles. Comparison between model predictions and the result of the DIA measurements shows that bubble breakage has a significant effect on the bubble size distribution especially at heights far from the distributor plate. Moreover, lateral bubble distribution of the bed was investigated

Novel phenomenological discrete bubble model of freely bubbling dense gas-solid fluidized beds : application to two-dimensional beds

A phenomenological discrete bubble model has been developed for freely bubbling dense gas–solid fluidized beds and validated for a pseudo-two-dimensional fluidized bed. In this model, bubbles are treated as distinct elements and their trajectories are tracked by integrating Newton's equation of motion. The effect of bubble–bubble interactions was taken into account via a modification of the bubble velocity. The emulsion phase velocity was obtained as a superposition of the motion induced by individual bubbles, taking into account bubble–bubble interaction. This novel model predicts the bubble size evolution and the pattern of emulsion phase circulation satisfactorily. Moreover, the effects of the superficial gas velocity, bubble–bubble interactions, initial bubble diameter, and the bed aspect ratio have been carefully investigated. The simulation results indicate that bubble–bubble interactions have profound influence on both the bubble and emulsion phase characteristics. Furthermore, this novel model may become a valuable tool in the design and optimization of fluidized-bed reactors