Abstract:

To investigate the influence of the structure of the reinforced fibers on field distribution in ionic membrane, the matter migration processes in the ion-exchange membrane (IEM) with the reinforced fibers in the presence of the electric field were simulated by using the percolation flow model in porous media, the transport of diluted species model and the secondary current distribution model. The convective velocity, concentration and current density in the ionic membrane were obtained. The effects of the shape, pitch and the mode of network of the reinforced fibers on the field distribution were studied. The ion concentration on the surface of the membrane after electrolysis was measured by photography and image processing technology. The experimental results were in good agreement with the simulation results. The results show that, the convective velocity at the central region encircled by the reinforced fibers is the highest. The closer to the reinforced fibers, the lower the velocity, the greater the concentration and the current density. Higher velocity and current density can be obtained in the ionic membrane by using the orthogonal reinforced fibers. The larger the distance between the ribs, the lower the current density, the more uniform the distribution. The highest value and the most inhomogeneous distribution of the current density can be obtained by using the ellipse reinforced fibers with its major axis vertical to the flow.

Key words: ion-exchange membranes, reinforced fiber, computational fluid dynamics, numerical simulation

摘要：

为研究加强筋结构对离子膜内场分布特性的影响，采用多孔介质渗流模型、稀物质传递及二次电流分布模型，对电场条件下含加强筋的离子膜内物质迁移过程进行了数值模拟，得到了物质在膜内的对流速度、浓度及电流密度分布，考察了加强筋形状、间距及成网方式对场分布特性的影响。利用拍照法和图像处理技术对电解后膜表面离子浓度进行了测量，实验结果与模拟结果吻合良好。结果表明，在加强筋所围成的空隙中心处对流速度最大；越靠近加强筋，速度越低，浓度和电流密度越大；采用正交型加强筋，膜内具有较高的对流速度和电流密度；加强筋间距越大，电流密度越低，分布越均匀；采用椭圆形长轴迎流的加强筋时，膜内具有最高的电流密度，但其电流密度分布最不均匀。

关键词: 离子膜, 加强筋, 计算流体力学, 数值模拟