• Applied Chemistry for Engineering
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• v.22 no.6
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• pp.703-710
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• 2011

As the spacer in the membrane module provide the channel space to flow the feed solution smoothly and induce the flow turbulence, it could help to reduce both the concentration polarization and to take the long-term operation of membrane modules with high permeate flux by mixing the accumulated contaminants on the membrane surface into the bulk solution. In this study, the concentration distribution in membrane module with respect to the spacers which have the cross-sectional shapes of circle, cross, diamond and hexagon, the angles of spacer configuration, solute rejection and permeate flux were interpreted and optimized numerically using the "COMSOL Multiphysics" software. The concentration on the membrane surface was kept the lowest level for the cross-shape among the above four types of spacers. Also the 30 degree spacer configuration was showed as the most efficient case. The concentrations on the membrane surface at the module outlet for without spacer and the cross shape with the 30 degree spacer configuration were 2.09 and 1.29 times higher than those at inlet, respectively. The reduction effect of concentration polarization increased rapidly as the permeate flux increased.

• Journal of Hydrogen and New Energy
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• v.33 no.3
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• pp.209-218
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• 2022

Recently, research on the development of anion exchange membranes (AEMs) has received considerable attention from the scientific community around the world. Here, we fabricated a series of AEMs with branched structures with different alkyl spacers and conducted comparative evaluations. The introduction of these branched structures is an attempt to overcome the low ionic conductivity and stability problems that AEMs are currently facing. To this end, branched polymers with different spacer lengths were synthesized and properties of each membrane prepared according to the branched structure were compared. The chemical structure of the polymer was investigated by proton nuclear magnetic resonance, Fourier transform infrared, and gel permeation chromatography, and the thermal properties were investigated using thermogravimetric analysis. The branched anion exchange membrane with (CH₂)₃ and (CH₂)₆ spacers exhibited ionic conductivities of 8.9 mS cm^-1 and 22 mS cm^-1 at 90℃, respectively. This means that the length of the spacer affects the ionic conductivity. Therefore, this study showing the effect of the spacer length on the ionic conductivity of the membrane in the polymer structure constituting the ion exchange membrane is judged to be very useful for future application studies of AEM fuel cells.

• Membrane and Water Treatment
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• v.6 no.6
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• pp.513-524
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• 2015

In this study, the effects of the angles of spacer filaments and the different feed Reynolds number on the fluid flow behavior have been investigated. Three-dimensional computational fluid dynamics (CFD) study is carried out for fluid flow through rectangular channels within different angles ($30^{\circ}$, $40^{\circ}$, $50^{\circ}$, $60^{\circ}$, $70^{\circ}$, $80^{\circ}$, $90^{\circ}$, $100^{\circ}$, $110^{\circ}$, $120^{\circ}$, respectively) between two filaments of spacer for membrane modules. The results show that the feed Reynolds number and the angles of spacer filaments have an important influence on pressure drop. While the feed Reynolds number is fixed, the optimal angle of spacer should be between $80^{\circ}$ to $90^{\circ}$, because the pressure drop is not only relatively small, but also high flow rate region expanded significantly with the increase of the angles between $80^{\circ}$ to $90^{\circ}$.The Contours of velocities and change of the average shear stress with the different angle of spacer filaments confirm the conclusion.