计算流体动力学在反渗透膜进水流道设计中的应用

Application of computational fluid dynamics in design of inlet spacer of reverse osmosis membrane

为了优化反渗透卷式膜组件结构,进而提高膜组件性能,利用计算流体力学(computational fluid dynamics,CFD)软件,建立反渗透进水流道网格单元的二维模型,对反渗透进水流道网格内的速度场进行数值模拟,研究隔网纤维丝断面形状、位置对反渗透过程中压力损失及膜体内流体速度变化的影响,考察进水流道网格纤维丝形态及位置对流道内传质效果、涡流程度的影响。结果表明:得到优选的纤维丝结构——纤维丝断面为椭圆形,椭圆形断面与平行于原水方向呈+20°和-20°交替出现的网格,且纤维丝交点有凸出滑半球的隔网形态。

In order to optimize the structure of reverse osmosis(RO)membrance module and improve the performance of membrance module,a two-dimensional model of inlet spacer is established by CFD,and the spacer with different shapes of cross-section,different positions and different entry angle of the inlet spacer is analyzed.By studying the two important parameters of the spacer in RO membrane application,such as pressure loss and the change of fluid velocity in the membrane,the influence of different shapes of cross-section and positions on mass transfer effect and vortex degree in the inlet are obtained.The results show that an optimal spacer is obtained which with elliptical cross-section with smooth hemisphere cross points,and the elliptical cross section alternated from a grid of+20°to-20°with the direction of raw water parallel.