Pulsed gas regulation on heat and mass transfer behaviors in a wet particle fluidized bed

Abstract

Fluidized beds are widely used for energy conversion and often feature complicated meso-scale structures (e.g. bubbles/agglomerations) that can weaken or enhance heat and mass transfer characteristics. To optimize performance, the flow regime in a fluidized bed must be carefully controlled. We present a revised discrete element method, validated by calculating the hot sphere cooling period. This work focuses on multiphase momentum, energy and mass exchanges, and analyzes methods for regulating and improving heat and mass transfer capabilities by introducing pulsed gas. A liquid bridge force controlling parameter, reflecting the relative contributions of the liquid bridge force and other forces, is defined for in-depth analyses. We found that the force controlling parameter is greater than unity in the dense region where the emulsion phase accounts for 15%. This indicates that decreasing the percentage of emulsion phase could effectively improve heat and mass transfer characteristics. The application of pulsed gas was effective for controlling the flow regime and reducing unfavorable meso-scale structures, thereby providing a potential means of regulating the heat and mass transfer characteristic of industrial processes.