Abstract This study evaluated the impact of precise representation of spacer geometry on numerical simulations of hydrodynamics and solute transport in feed channels of membrane processes. Three levels of increasing geometry accuracy were assessed: i) cylindrical filaments, ii) filaments with circular sections of variable diameter based on microscopic measurements, and iii) geometries obtained from X-ray computed tomography (CT scans) in three resolutions (22 µm, 11 µm, and 5.5 µm). The three-dimensional CT scans revealed quasi-elliptic, not circular, cross-sections of the filaments. Microscopic measurements fail to account for this ellipticity, resulting in overestimation of pressure drop calculated at industry-typical average velocities (0.07–0.15 m s−1) by a factor of 1.8 compared to CT-based geometries. On the other hand, the cylindrical spacer filaments representation overestimates concentration polarization at the membrane surface compared to CT-based geometries. Experimental results of pressure drop and particle deposition were in close agreement with simulations using CT scanned geometries. This work demonstrates that modeling results depend significantly on the spacer geometry accuracy. Within the investigated CT scan accuracies 20 µm was found sufficient for modeling hydrodynamics and solute transport in spacer-filled feed channels. The results may be useful for reliable investigation and development of novel spacer geometries.

中文翻译：

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膜进料隔板的 CT 扫描——隔板模型精度对膜进料通道中流体动力学和溶质传输建模的影响

摘要 本研究评估了间隔几何形状的精确表示对膜过程进料通道中流体动力学和溶质传输的数值模拟的影响。评估了几何精度提高的三个级别：i) 圆柱形灯丝，ii) 基于显微测量具有可变直径的圆形截面的灯丝，以及 iii) 从 X 射线计算机断层扫描 (CT 扫描) 获得的几何结构，三种分辨率 (22 µm， 11 µm 和 5.5 µm）。三维 CT 扫描显示细丝的横截面为准椭圆形，而不是圆形。微观测量无法解释这种椭圆度，导致与基于 CT 的几何形状相比，以工业典型平均速度 (0.07–0.15 m s-1) 计算的压降高估了 1.8 倍。另一方面，与基于 CT 的几何形状相比，圆柱形间隔丝表示高估了膜表面的浓度极化。压降和颗粒沉积的实验结果与使用 CT 扫描几何形状的模拟非常一致。这项工作表明，建模结果在很大程度上取决于垫片几何精度。在所研究的 CT 扫描精度中，发现 20 µm 足以模拟填充垫片的进料通道中的流体动力学和溶质传输。结果可能有助于可靠地研究和开发新型垫片几何形状。压降和颗粒沉积的实验结果与使用 CT 扫描几何形状的模拟非常一致。这项工作表明，建模结果在很大程度上取决于垫片几何精度。在所研究的 CT 扫描精度中，发现 20 µm 足以模拟填充垫片的进料通道中的流体动力学和溶质传输。结果可能有助于可靠地研究和开发新型垫片几何形状。压降和颗粒沉积的实验结果与使用 CT 扫描几何形状的模拟非常一致。这项工作表明，建模结果在很大程度上取决于垫片几何精度。在所研究的 CT 扫描精度中，发现 20 µm 足以模拟填充垫片的进料通道中的流体动力学和溶质传输。结果可能有助于可靠地研究和开发新型垫片几何形状。