Simulation of the Effect of a Baffle Structure on Membrane Efficiency Using Computational Fluid Dynamics during the Clarification of Pomegranate Juice

Background and Objectives: Pomegranate juice (PJ) contains large particles that stick to evaporator walls causing off flavors in the concentrate due to burning. Microfiltration is used to clarify PJ. Fouling is a limiting phenomenon that can prevent the industrialization of membrane clarification. Changes in the geometry of the membrane module such as using baffles are useful to decrease this problem. Computational fluid dynamics (CFD) is a powerful numerical tool used in modeling membrane processing. Materials and Methods: The effect of baffle geometry on the efficiency of membrane clarification of pomegranate juice in a flat-sheet module was simulated using computational fluid dynamics (CFD). The geometry of the membrane unit was plotted and meshed with Gambit software, and was solved using FLUENT software. A two-dimensional double-precision method at steady state was selected to simulate the membrane process. The convective terms were discretized with a standard first-order upwind scheme in computational solution. The RNG k-  model was used due to its high accuracy in eddy flows with a low Reynolds number. The effects on the process performance of the number of baffles, their angle and the distance between the baffles and the membrane surface were evaluated. Results: The results showed that the configuration with the feed-channel height of 2 cm, the baffle angle of 90o and the distance between the membrane surface and baffles of 2 mm had maximum permeate flux. Conclusions: Reducing the distance between the baffles and the membrane surface increased the permeate flux due to create an eddy flow near the membrane surface in the flat-sheet module and reduced the total and cake-layer resistances. Keywords: Baffle, Computational fluid dynamics, Juice, Membrane, Pomegranate