Transition of the Flow Regime Inside of Monolith Microchannel Reactors Fed with Highly Turbulent Flow

Abstract

This paper investigates the flow behaviour of monolith microchannels. Specifically, the study characterizes the flow regime within in-series monolith channels where highly turbulent flow approaches them but inside of the channels, the Reynolds number is subcritical. Results from LES and a transitional RANS model are compared to those obtained when directly assuming laminar flow inside of the channels. A space-resolved model of channels placed in series and channel Reynolds numbers ranging from 50 to 300 are considered. The results show that the flow pattern in is almost identical in the two channels and that the frequency of fluctuations tends to increase with the Reynolds number. The flow regime in both channels is unsteady laminar, containing a wide spectrum of frequencies. The tested transitional RANS model (k-kL-ω) is unable to capture the velocity fluctuations predicted by LES. Despite the differences in the velocity field prediction, the pressure drop estimation from all models is practically the same. This study provides insights into the flow behaviour of monolith reactors and is useful for reactor design and optimization.