Mechanistic integration of interparticle forces into umf prediction for fine and ultrafine particles

The practical design and operation of high-temperature gas–solid fluidized bed reactors require a comprehensive understanding of the minimum fluidization velocity ( u mf ) and interparticle forces (IPFs), as these parameters critically govern bed stability, hydrodynamics, and overall reactor performance. Experimental measurements of u mf and IPFs at elevated temperatures, particularly for fine/ultrafine materials, have been challenging due to the lack of appropriate methodologies. In this study, we developed a novel theoretical model and experimental protocol to indirectly quantify the IPFs and estimate the u mf in gas–solid fluidized systems. This model establishes a direct correlation between IPFs and u mf , providing a mechanistic understanding of how cohesion interactions for Geldart A-C powders affect fluidization hydrodynamics at elevated temperatures. Compared with traditional correlations, the two newly developed models exhibited enhanced predictive accuracy for the u mf of inert (alumina and silica sand) and mineral solids (phosphate ore, calcium sulfate, phosphogypsum, calcium oxide) across a wide range of temperature from ambient to 600 °C. Among them, the interparticle force model demonstrated the highest predictive accuracy, with an average absolute deviation (AAD) of 18.6 %.