平板膜组件内部流体流动状态的可视化

Flow visualization through channels in plate-and-frame modules

自行设计了透明的有机玻璃膜组件,用于直接观测组件内部流体流动状态。分别测定了空流道和含有料液隔网流道的压力损失,并根据摩擦因子f随Re值的变化曲线确定了临界Reynolds数(Rec)的范围。结果表明,含有料液隔网流道的Rec相比空流道大大减小。利用注射颜料的方法对流体流动情况进行观测,验证了上述结果。随后测定了表面粗糙度、隔网排布形式、孔隙率对流体流动情况的影响。最后,自制小型卷式膜进行测试,结果与平板膜的压力损失情况相符,表明平板膜的实验结果可以用于预测卷式膜的行为。

A Perspex test cell was made to observe the flow regime directly in plate-and-frame modules under different conditions. The pressure drops in channels with and without spacer were examined. The critical Reynolds number（Rec） were determined with the correlations for Re and friction factors. The results showed that Rec in the spacer filled channel was much smaller than that in the empty one, indicating that the turbulence regime was reached at lower fluid velocity. The results were verified through the dye injecting method. Channels with different surface roughness, spacer arrangement and spacer porosity were also investigated. Finally, a laboratory scale spiral-wound module was made and a similar pressure drop situation was obtained, which confirms that the method is also suitable for the spiral-wound modules.