CFD simulation of effect of baffle on mass transfer in a slit-type pervaporation module

Abstract

A pervaporation simulation was conducted to describe mass transfer in a slit membrane module that contained mixing-promoting baffles for efficient removal of volatile organic compounds. Commercial computational fluid dynamics (CFD) package was employed to solve hydrodynamics and mass transfer equations. The effects of baffle on enhancing mass transfer in the module were examined. Numerical simulation results indicated 14, 24, and 34% improvements of the average mass transfer coefficient within the flow channel with baffle height of 10, 30, and 50% of the slit height of the module, reaching 1.25 × 10 −5 m/s, 1.35 × 10 −5 m/s, 1.44 × 10 −5 m/s, respectively, as compared with 1.08 × 10 −5 m/s where there was no baffle. In all cases, a second peak of the local flux was observed due to the disruption of the developed boundary layer around the baffle. Separation of the boundary layers was observed for baffles with 30 and 50% of the slit height. The pressure drops over the channel length were compared. An increase in 2, 4, and 27% in pressure drop corresponding to the aforementioned three different baffle heights were observed. The effect of multiple baffles on mass transfer depends on the locations of the second baffle. The effect of multiple baffles in the module is insignificant. Pervaporation (PV) experiments were conducted using polydimethylsiloxane membrane with baffle attached and compared with the simulation results. The experimental result showed good agreement with the simulation results at low Reynolds numbers (<1000).