CFD SIMULATIONS OF GAS AND LIQUID SLUGS FOR TAYLOR FLOW IN A MICROCHANNEL

ABSTRACT The rapid development of microfabrication techniques creates new opportunities for applications of microchannel reactor technology in chemical reaction engineering. The extremely large volume-to-surface ratio and the short transport path in microchannels enhance heat and mass transfer dramatically and hence provide many potential opportunities in chemical process development and intensification. Multiphase reactions involving gas/liquid reactants with a solid as a catalyst are ubiquitous in the chemical and pharmaceutical industries, and the hydrodynamics play a prominent role in reactor design and performance. For gas/liquid two-phase flow in a microchannel, the Taylor slug flow regime is the most commonly encountered flow pattern, therefore the present study deals with the numerical simulation of gas and liquid slugs in a microchannel. A T-junction microchannel (empty or packed) with varying cross-sectional width (0.25, 0.5, 0.75, 1, 2 and 3 mm) served as the model micro-reactor, and a finite volume based commercial CFD package, FLUENT, was adopted for the numerical simulation. The gas and liquid slug lengths at various operating conditions were obtained and found to be in good agreement with the literature data. Keywords: Taylor flow; Liquid and gas slugs; Microchannel; Numerical simulation INTRODUCTION The microchannel reactor has many advantages over conventional macroreactors. With its small transverse dimensions (submillimeter), the microchannel reactor possesses extremely high surface to volume ratios, and consequently exhibits enhanced heat and mass transfer rates. Scale-up for high throughput is achieved by simple replication of microreactor units; which eliminates costly reactor redesign and pilot plant experiments, thus shortening the development time from laboratory to commercial production. There are numerous potential applications for microchannel reaction technology in chemical and biological engineering, which are suitable for various types of reactions, from thin-wall reactors, membrane reactors to packed bed reactors, and from single phase reactions to multiphase reaction