MICRO-SCALE STABILITY OF BUBBLY FLOWS IN PACKED BEDS

Bubbly liquid downflow through fixed beds and its transition to dispersed-bubble flow is modeled. At the macro (bed) scale the system is described as a compressible fluid filtrating through porous media. The system peculiarities- the isothermal variation of perfect gas in the spherical bubbles, weak compressibility of the liquid etc.- are accounted for at the micro (pore) scale in the state equation. Dimensionless criteria were found determining the bubbly-liquid flow in packings and its micro-scale stability. Part of the criteria were omitted due to their small input, while the rest are contained in a relation following from the micro-level stability criterion: the bubble size growing under a pressure drop across the bed does not exceed the capillary throat. The modeling results are in fair agreement with the experimental data. 1