Review on hydrodynamics and mass transfer in minichannel wall reactors with gas–liquid Taylor flow

Over the past decades, Taylor flow has got an increasing interest due to its potential to intensify reaction processes with fast kinetics which are usually controlled by mass transfer processes. Besides high mass transfer rates, the segmented flow regime offers a sharp residence time distribution of the liquid phase and a low pressure drop. Taylor flow appears in micro and minichannels whereas the terms have not always been used with a clear distinction. Minichannels are channels with characteristic diameters between 400 μm and about 1 mm, which will be in the centre of this work. These channel dimensions appear in monolithic reactors also known as reactors with honeycomb catalyst packings, in concepts using bundles of capillary tubes, as well as in microchannel plate reactors.This article presents a comprehensive overview of hydrodynamics and mass transfer in the minichannels of an open flow structure, i.e. in channels without internals, operated in the Taylor flow regime. The review summarises available correlations to predict Taylor flow characteristics, as well as mass transfer coefficients between all involved phases (gas–liquid, liquid–solid, gas–solid). Within this scope, the impact of operational and design parameters is critically discussed and limits of application for the individual correlations are defined. Special attention is given to the interaction of these mass transfer steps in heterogeneously catalysed chemical reactions.