TY - JOUR
T1 - CT scanning of membrane feed spacers – Impact of spacer model accuracy on hydrodynamic and solute transport modeling in membrane feed channels
AU - Horstmeyer, Nils
AU - Lippert, Thomas
AU - Schön, David
AU - Schlederer, Felizitas
AU - Picioreanu, Cristian
AU - Achterhold, Klaus
AU - Pfeiffer, Franz
AU - Drewes, Jörg E.
PY - 2018
Y1 - 2018
N2 - 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.
AB - 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.
KW - Computational fluid dynamics (CFD)
KW - Feed channel
KW - Feed spacer 3-D geometry
KW - Mass transfer
KW - Particle deposition
KW - Scan accuracy
KW - X-ray computed tomography (CT)
UR - http://www.scopus.com/inward/record.url?scp=85049747783&partnerID=8YFLogxK
U2 - 10.1016/j.memsci.2018.07.006
DO - 10.1016/j.memsci.2018.07.006
M3 - Article
AN - SCOPUS:85049747783
SN - 0376-7388
VL - 564
SP - 133
EP - 145
JO - Journal of Membrane Science
JF - Journal of Membrane Science
ER -