Liquid residence time distribution of multiphase horizontal flow in packed bed milli-channel: Spherical beads versus open cell solid foams.

A robust approach to access liquid residence time distribution (RTD) adapted to multiphase flow in porous media is presented. It is tailored to meet specific requirements of small scale systems (centimeter, millimeter or less) with Taylor segmented flow feed. The method involves direct visualization using fluorescence microscopy close to both extremities of a porous packing. Critical image treatment steps and optimization of a versatile discrete model with 4 parameters are detailed and discussed. They allow the precise and rapid determination of RTD curves and their 1st- and 2nd-order moments. The application of the method is successfully illustrated with dense micro-packed beds of sub-millimeter particles and highly porous media like open cell solid foams undergoing a preformed G-L segmented (Taylor) flow. Original results regarding the effect of fluid flowrates and different confined porous media are discussed and lead to a single two-parameter liquid hold up correlation, which is valid for both packings. As usual, RTD broadening is treated as a combination of convective dispersion and mass transfer to a fraction of immobile liquid. The predominant role of mass transfer is underlined with an analysis of characteristic times. [ABSTRACT FROM AUTHOR]