Chapter 9. FILTRATION Part III. Selected methods for improving filtration properties

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Chapter 9.FILTRATIONPart III. Selected methods
for improving filtration properties
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• 9.1 Summary of selected methods for improving
  filtration properties
• Filter density growth
• Filter thickness growth
• Defined fiber orientation
• Pleated filters
• Electrically charged filters
• Fiber diameter, microfibers, nanofibers
• Fiber shape

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9.2 Filter density growth Filter density ? (or
packing fraction c) increases filter efficiency
and pressure drop too. 9.2.1 Relation between
packing fraction and filter efficiency We can
suppose relation between packing fraction c and
these filtration mechanisms (see chapter 8.3 and
8.4) 1. Inertial impaction Eir ? - 1/(ln c)2
(9.1) 2. Diffusional deposition ED ?
-1/(ln c)1/3 (9.2) 3. Sieve
effect (9.3)
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9.2.2 Relation between packing fraction and
pressure drop According to cell theory of
Kuwabara for cylindrical fibers oriented
perpendicularly to flow we define
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