A theoretical study of permeability enhancement for ultrafiltration ceramic membranes with conical pores and slippage
Ceramic membranes are currently favourable in membrane filtration applications due to their excellent mechanical strength, thermal and chemical resistance, backflush capability, and thus a long-service cycle. Coated on top of a mesoporous support, the selective top layer of ultrafiltration ceramic m...
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Published in | Physics of fluids (1994) Vol. 31; no. 2 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
Melville
American Institute of Physics
01.02.2019
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Subjects | |
Online Access | Get full text |
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Summary: | Ceramic membranes are currently favourable in membrane filtration applications due to
their excellent mechanical strength, thermal and chemical resistance, backflush
capability, and thus a long-service cycle. Coated on top of a mesoporous support, the
selective top layer of ultrafiltration ceramic membranes has pore size not exceeding a few
tens of nanometers and thickness in the order of O10 μm. In fact, the
permeability of an ultrafiltration ceramic membrane can be estimated by the permeability
of the top layer due to its smallest pore size. Without impairing the filtration function
but still improving the permeability, a gradient conical pore shape is proposed. Two
formulae for the filtrate flow rate versus pressure drop relationship through a conical
pore exhibiting surface slippage are established here by extending the Hagen-Poiseuille
law and an analytical solution for the axisymmetric creeping flow. It is analytically
proved that the surface slip length in a conical flow is proportional to a local pore
radius by a slip coefficient that is unique for a given pore configuration at a prescribed
flow rate. The permeability of a conical-pore membrane is enhanced for radius ratio not
exceeding 6.5. The optimum configuration, achieved at a ratio of 2.3, produces an
enhancement factor for a membrane permeability of 1.5 for a no-slip surface; this
enhancement increases linearly with the slip coefficient if a surface slippage exists. |
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ISSN: | 1070-6631 1089-7666 |
DOI: | 10.1063/1.5085140 |