Numerical study of mass transfer in three-dimensional spacer-filled narrow channels with steady flow

A Computational Fluid Dynamics (CFD) model was used to simulate steady fluid flow with mass transfer in three-dimensional narrow channels containing non-woven spacers with a df/hch ratio of 0.6, and a lm/hch ratio of 4, positioned at 45° and 90° angles against the flow direction. A solute with a Schmidt number of 600 dissolving from the wall and hydraulic Reynolds numbers up to 200 for 3D geometries, and up to 500 for 2D geometries were considered. Greater mass transfer enhancement was found for the 3D geometries modeled, when compared with 2D geometries, due to wall shear perpendicular to the bulk flow and streamwise vortices. The regions of high mass transfer were found to correlate mainly with those regions where the fluid flow is towards the wall. The relationship between 3D flow effects, pressure drop and mass transfer was investigated. Form drag was identified as the main component of energy loss for the flow conditions analyzed. Implications for the design of improved spacer meshes are discussed.