CFD and lower order mechanistic models for gas-liquid flow in NETmix: Pressure drop and gas hold-up

This study evaluates a 2D two-phase computational fluid dynamics (CFD) model, based on the Volume-of-Fluid approach, to represent the air-water co-current downwards flow inside the micro/meso structured static mixer, NETmix. The 2D model was suitable for representing properties more reliant upon the shape and size of the bubbles, such as the gas hold-up. Additionally, it was measured the two-phase pressure drop associated with the NETmix, through which it was observed a capability of the NETmix to operate at a lower pressure drop than some common static mixers. Using both CFD and experimental measurements, a method for predicting the gas hold-up and a mechanistic model to predict the two-phase pressure drop in static mixers were proposed, both based on previous works. A maximum deviation from the reference data of 7.2% and 17.0% was found between the predictions of the proposed gas hold-up method and the two-phase pressure drop, respectively.