Predicting power consumption in continuous oscillatory baffled reactors

Abstract

Continuous oscillatory baffled reactors (COBRs) have been proven to intensify processes, use less energy and produce fewer wastes compared with stirred tanks. Prediction of power consumption in these devices has been based on simplistic models developed for pulsed columns with single orifice baffles several decades ago and are limited to certain flow conditions. This work explores the validity of existing models to estimate power consumption in a COBR using CFD simulation to analyse power density as a function of operating conditions (covering a range of net flow and oscillatory Reynolds numbers: Renet=6-27/Reo=24-96) in a COBR with a single orifice baffle geometry. Comparison of computed power dissipation with that predicted by the empirical quasi-steady flow models shows that this model is not able to predict correctly the values when the flow is not fully turbulent, which is common when operating COBRs. It has been demonstrated that dimensionless power density is inversely proportional to the total flow Reynolds number in laminar flow and constant in turbulent flow, as is the case for flow in pipes and stirred tanks. For the geometry studied here P/V∗=330/ReT in laminar flow and P/V∗=1.92 in turbulent flow.