Dispersion during bubble-train flow in capillaries

The name bubble-train flow is used to identify the cocurrent flow of gas bu bbles and liquid slugs through a capillary. A model was developed to analyz e mass transfer between bubbles and liquid slugs during bubble train flow. This mass transfer model, derived from the equations of transport, is based on the fluid flow profiles and has no adjustable parameters. A comprehensi ve account of the experiments designed to test the model is presented. The single capillary model was used to analyze mass transfer of a passive salin e solution introduced as a pulse signal. Theoretical results were used to d etermine the concentration vs time distribution of the saline solution insi de the capillary channels. These results were compared with experimental re sidence times determined using a conductimetric technique. Very good agreem ent between theory and experiments was found for single capillaries. The ma ss transfer model, however, must be modified to take into account macroscop ic flow distribution effects before it can be used for the analysis of mass transfer and chemical reaction inside the monolith froth reactor. (C) 1998 Elsevier Science Ltd. All rights reserved.