Nanofibers New Developments in Filtration
Dr. Andreas Seeberger Mike Harriman
Abb.: 4, FotoNr.: 0606A00011, 1140 : 1 50 µm
NAFA Technical Seminar PhoenixAbb.: 26, FotoNr.: 0606A00035, AZ, 630 : 1 2012 50 µm 9. Symposium Textile Filter in Chemnitz, 2008 IREMA-FILTER and Aeolus Filter Corp.
• German Company • Located in Greensboro, NC • Manufacturer of synthetic filter media • Manufacturer of synthetic filters • Manufacturer of pleated products • Established 1997
Synthetic Filter Media for Automotive HVAC Industry
9. Symposium Textile Filter in Chemnitz, 2008 2 Let´s talk about fibers
What do you think when you hear „nanofibers“ ?
Small ? New technologies ? High performance filters ? Applications ? Use it ?
Today´s objective
Background information on fine and nanofiber filtration Capabilities for current air filtration requirements
9. Symposium Textile Filter in Chemnitz, 2008 3 Outline
History of Nanofibers in Filtration
Technical Characteristics of Nanofibers
Production Technologies
Performance in Filtration Applications
High Efficiency Filtration
Progressive Media Design
Examples
Summary
9. Symposium Textile Filter in Chemnitz, 2008 4 Outline
History of Nanofibers in Filtration
Technical Characteristics of Nanofibers
Production Technologies
Performance in Filtration Applications
High Efficiency Filtration
Progressive Media Design
Examples
Summary
9. Symposium Textile Filter in Chemnitz, 2008 5 A brief overview
The development of fine and nanofibers for filtration
• Conventional and natural man made fibers were > 10 µm
• Development of microfibers brought fibers < 10µm
• Microglass nanofibers (0.4 µm) widely available for decades
• Electrospun nanofibers used for 25 years, increasingly for 10-12 years
• Since 2000 nanofibers in focus of intensive research
• Meltspun polymer nanofibers since 2007
• Today: established products, ongoing R&D, new technologies
9. Symposium Textile Filter in Chemnitz, 2008 6 Outline
History of Nanofibers in Filtration
Technical Characteristics of Nanofibers
Production Technologies
Performance in Filtration Applications
High Efficiency Filtration
Progressive Media Design
Examples
Summary
9. Symposium Textile Filter in Chemnitz, 2008 7 Definition of Nanotechnology
Head of a pin -2 1 cm 10 10 (~ 1-2 mm) mm Micro Electro Ant (~ 5 mm) 10-3 1 Mechanical Devices
mm (~ 10-100 μm wide) Milliscale
-4 0,1 mm Dust Mite 10 100 μm (~ 200 Human hair
μm) (~ 60-120 μm wide) -5 0,01 10 mm 10 μm Red blood Red blood cell with Pollen 10-6 grain cells white cell Microscale Visible (~ 2-5 μm) Spectrum 10-7 10 μm 100 nm
Nanofibers 0,01 10-8 DNA μm 10 (~ 20-500 nm) (~ 1-1/2 nm) nm Stacks of clay mineral -9 pletelets, each platelet 10 Abb.: 26, FotoNr.: 0606A00035, 630 : 1 50 µm Nanoscale 1 nm with ~ 1 nm thickness
Carbon Nanotube 5 Atoms of silicon - 10 10 0,1 nm (~ 2 nm diameter) (~ 1nm)
9. Symposium Textile Filter in Chemnitz, 2008 8 Definition of Nanofibers for Filtration
The definition of nanofibers for filtration
Today: Nanotechnology = smaller than 0.1 µm (100 nm) Common in filtration: Fiber diameter < 0.5 µm (500 nm) Former barrier to achieve fiber diameters < 1 µm
Start of „nano“-effects from 500 nm and below
9. Symposium Textile Filter in Chemnitz, 2008 9 Outline
History of Nanofibers in Filtration
Technical Characteristics of Nanofibers
Production Technologies
Performance in Filtration Applications
High Efficiency Filtration
Progressive Media Design
Examples
Summary
9. Symposium Textile Filter in Chemnitz, 2008 10 Production Technologies
Manufacturing Electrospinning Techniques Meltblown
Synthetic Island-In-The-Sea
Centrifuge Spinning Glass Fiber
Wet Laid Microglass Others
9. Symposium Textile Filter in Chemnitz, 2008 11 Glass fibers
Source: Owens9. Symposium Corning Fiberglas Textile Corporation, Filter in Chemnitz, Journal of 2008 the Air Pollution Control Association 1962 12 Wet-laid microglass production
Distributor Web Formation Binder Application Drying
Source: I. Lappas,9. Symposium Filtrex ASIA, Textile New Filter-Delhi in2010 Chemnitz, / / Dynatec 2008 13 Microglass Composition
Composition „E“-Glass „C-Glas“ Binder Systems
Silicon dioxide 52-56 % 60-65 % Latex
Calcium oxide 16-25 % - Melamine
Aluminium oxide 12-16 % 2- 6 % Phenolic
Boron oxide 8-13 % 2- 7 % Epoxy
Sodium and 0- 1 % 8-12 % potassium oxide Mognesium 0- 6 % - oxide Magnesium - 15-20 % oxide and calcium oxide
9. Symposium Textile Filter in Chemnitz, 2008 14 Microglass characteristics
Microglass filter media
• Can have very low fiber diameters (0.3 µm)
• Is available with large variety of filtration characteristics
• Is filter media of choice for high efficiency (HEPA) applications
• Has advantages and disadvantages
(efficiency vs. handling/moisture resistance/shedding
• Is tried to be replaced in increasing number of applications
• Is NOT focus of today´s presentation
9. Symposium Textile Filter in Chemnitz, 2008 15 Polymer Nanofibers
Tissue engineering scaffold Medical prosthesis Adjustable biodegradation rate Wound dressing Lower stress concentration Better cell attachment Prevents scar Higher fracture strength Contraollable cell directional growth Bacterial shielding
Filter media Heamostatic devices Higher efficiency in fluid Improved adsorption performance
Protective clothing Polymer Optical applications Breathable fabric that blocks chemicals Nanofibers Liquid crystal optical shutters Cosmetics High utilization Electrical conductors Higher transfer rate Ultra small devices
Material reinforcement Drug delivery Sensor devices Higher fracture toughness Increased dissolution rate Higher sensitivity Higher delamination resistance Drug-nanofiber interlace For celd, arteries and veins
16 9. Symposium Textile Filter in Chemnitz, 2008 Island-In-The-Sea
Spinning of bicomponent fibers Island-in-the-sea structure Different geometries Dissolving sea-polymer
Source: Kuraray
Advantages Disadvantages
Standard spinning processes for bico-fibers Nano-range not easy achievable Narrow diameter range Solvent use Two-step-process
9. Symposium Textile Filter in Chemnitz, 2008 17 Electrospinning
Advantages Disadvantages
Fiber diameters as low as 50 nm Low production rate Various polymers applicable Use of environmentally critical solvents Homogeneous fiberdiameters Two-step-process Fibers only in layers
9. Symposium Textile Filter in Chemnitz, 2008 18 Meltblown
polymer
hot air hot air polymer Recently increasing R&D activities air air New improvements for finer fiber diameters
spinneret
fibers
Advantages Disadvantages
High productivity normal operation: fiber diameters of Solvent free only 1-2 microns Single step process
9. Symposium Textile Filter in Chemnitz, 2008 19 Outline
History of Nanofibers in Filtration
Technical Characteristics of Nanofibers
Production Technologies
Performance in Filtration Applications
High Efficiency Filtration
Progressive Media Design
Examples
Summary
9. Symposium Textile Filter in Chemnitz, 2008 20 The impact of nanofibers on filtration
η = viscosity
tU0 f Decreasing pressure drop p df = diameter of the fiber 2 t = thickness of filter d f
U0 = face velocity of filter Slip Flow Effect α = Volume fraction of fibers in a filter Kn fiber volume r 1 porosity f total volume
Increasing collection efficiency
High inner surface area
Improved media design possibilities
More distinct progressivity
9. Symposium Textile Filter in Chemnitz, 2008 21 Filtration Markets for polymeric nanofiber products
HVAC Dust Collection HEPA Filtration
Automotive Vacuum Cleaners
EDM Fuel Filtration
Battery Separator Protective Clothing
9. Symposium Textile Filter in Chemnitz, 2008 22 High Efficiency Synthetic Filter Media
Nanofiber Product Electrete Product
High efficiency products Very low initial resistance
Well balanced pressure drop Mostly medium efficiencies
No or little discharge Strong discharge possible
Very reliable filtration „Insecure“ performance
All hydrophobic synthetic media show electrete effects of different strength Combination of nanofiber and electrete technology Influence of electrete effect only detectable by discharge treatment
9. Symposium Textile Filter in Chemnitz, 2008 23 Approach of IREMA and AEOLUS: Integrated Nanofiber Technology
Integration of polymer nanofibers into nonwoven material
Inline Process
Solvent free fabrication of fibers with different diameters
Task specific fiber diameters for filtration
Gradient control of nanofiber distribution Patented Technology
Enhanced filtration performance
One-layer pleatable filter material
Unmixed Material
9. Symposium Textile Filter in Chemnitz, 2008 24 Integrated Nanofiber Technology for improved filter media
Developing of new synthetic filter media
•Higher mechanical efficiencies •Higher capacities •Low pressure drops
Nanofiber products not only for high efficiency filtration, but also for basic fine dust filtration and even prefiltration applications !
9. Symposium Textile Filter in Chemnitz, 2008 25 Fine dust filtration for Merv 13-A applications – Discharge Treatments
Objects
• Investigate influence of electrostatic charges • Inactivation by impinging particles • Long term stability / natural decay rate • Efficiency prediction in real applications
Investigations on filter Treatment methods discharge treatments • Superfine KCl • Nordtest / SINTEF • Isopropyl alcohol (IPA) • ASHRAE research projects RP 1189/1190 • Soot • EUROVENT 2004 round robin test • Detergents • R&D of filter companies Still lack of information/transparency
9. Symposium Textile Filter in Chemnitz, 2008 26 Fine dust filtration for Merv 13-A applications – Filter Media
Fine dust filter media IFN 80 – showing full potential of nanotechnology !
Mechanical protection
Nanofiber zone
Transition region
Stabilisation zone
9. Symposium Textile Filter in Chemnitz, 2008 27 Comparison of treatments for synthetic filter media
prEN779:2010 ASHRAE 52.2 Diesel soot Appendix J
• Isopropyl alcohol • Conditioning step: • Diesel soot (IPA)treatment to nanoparticles superfine KCl simulate discharge treatment to effects (sub 0.1 µ) investigate effects • Minimum DEHS • Loading until on efficiency efficiencies must be minimum efficiency • sub 0.1 µm particles reached (0.4 µ): (0.4 µ KCl) is reached F7: 35 % F8: 55 % F9: 70 %
Independent Testing
9. Symposium Textile Filter in Chemnitz, 2008 28 EN779: F7 panel filter with integrated nanofibers
100 prEN779:2010 90 80 F7 filter class • Isopropyl alcohol 70 (IPA) treatment to 60 simulate discharge 50 Efficiency DEHS [%] effects 40 untreated • Minimum DEHS
30 DEHS Efficiency [%] Efficiency DEHS efficiencies must [%] Efficiency DEHS Efficiency DEHS [%] 20 be reached (0.4 µ): completelyEfficiency immersed DEHS [%] in 10 untreated F7: 35 % IPA and dried for 24 h 0 0,1 1 10 Particle Size [µm]
EN779:2010 test of panel filter with IREMA IFN80 nanofiber media
Cond.: 593x593x95 mm, EN779 standard test, 3400 m3 h-1
9. Symposium Textile Filter in Chemnitz, 2008 29 Ashrae 52.2: Merv 13 panel filter with integrated nanofibers
100 ASHRAE 52.2 Standard 90 80 • KCl efficiency 70 Efficiency DEHS [%] untreated 60 50 Efficiency DEHS [%] 40 discharged by IPA Efficiency [%] Efficiency 30 20 Efficiency KCl [%] 10 untreated 0 0,1 1 10 Particle Size [µm]
Ashrae 52.2 test of panel filter with IFN80 nanofiber media
Cond.: 593x593x95 mm, Ashrae Dust, 3350 m3 h-1
9. Symposium Textile Filter in Chemnitz, 2008 30 Ashrae conditioning characteristics
Peak at 40 nm
30000 KCl conditioning aerosol
25000
20000
15000 Counts 10000
5000
0 0,001 0,01 0,1 1 Particle Size [µm]
Average number distribution of ambient Particle size distribution at Ashrae 52.2 air particles from the Pittsburgh Air conditioning step Quality Study (PAQS)
Atmospheric Environment 38 (2004) 3275–3284
9. Symposium Textile Filter in Chemnitz, 2008 31 Ashrae 52.2: Merv 13-A panel filter w. integrated nanofibers
100 ASHRAE 52.2 90 Appendix J 80 Efficiency DEHS [%] 70 untreated • Conditioning step: 60 Efficiency DEHS [%] superfine KCl 50 discharged by IPA (sub 0.1 µ) 40 • Loading until [%] Efficiency 30 MERV 13-A Efficiency KCl [%] minimum 20 untreated efficiency (0.4 µ 10 Efficiency KCl [%] KCl) is reached 0 discharged by • No p increase 0,1 1 superfine KCl 10 during loading Particle Size [µm]
Ashrae 52.2 test of panel filter with IFN80 nanofiber media including Appendix J conditioning step
Cond.: 593x593x95 mm, Ashrae Dust, 3350 m3 h-1
9. Symposium Textile Filter in Chemnitz, 2008 32 Variability of Ashrae 52.2 KCl Conditioning
Ashrae 52.2 test of non-electret filters including Appendix J conditioning step in different US laboratories
Air Media (Fall 2008) 12-13
9. Symposium Textile Filter in Chemnitz, 2008 33 Soot loadig: F7 integrated nanofiber media
Peak at 70 nm Measurement of NaCl efficiency 350 100 300 90 250 80 70 200 60 150 50 100 40 Initial Efficiency NaCl
Efficiency [%] Efficiency 30
Particle number [10k] number Particle 50 Initial efficiency KCl 20 Initial efficiency DEHS 0 10 0,01 0 0,1 1 Particle0,1 size [µm] 1 10 Particle size distribution of soot Particle size [µm]
Efficiencies of various aerosols on IREMA IFN80 nanofiber media
Cond.: velocity approx. 0.15 m/s, efficiency measurements with NaCl and soot
9. Symposium Textile Filter in Chemnitz, 2008 34 Soot loadig: F7 integrated nanofiber media
100 90 80 70 60 No efficiency 50 drop during soot 40 loading seen 30 Efficiency NaCl [%] NaCl Efficiency 20 Initial Efficiency (APS) 10 0 +50 Pa soot (APS) 0,01 0,1 1 10
Particle size [µm]
Soot loading on IREMA IFN80 nanofiber media
Cond.: velocity 0.15 m/s, efficiency measurements with NaCl
9. Symposium Textile Filter in Chemnitz, 2008 35 Soot loadig: F7 integrated nanofiber media
100 90 80 70 60 50 40 30 Initial Efficiency (SMPS) Efficiency NaCl [%] NaCl Efficiency 20 Initial Efficiency (APS) 10 +50 Pa soot (SMPS) 0 +50 Pa soot (APS) 0,01 0,1 1 10
Particle size [µm]
Soot loading on IREMA IFN80 nanofiber media
Cond.: measurements at velocity 0.15 m/s, efficiency measurements with NaCl, no merging procedure of SMPS and APS results
9. Symposium Textile Filter in Chemnitz, 2008 36 Evaluation of IFN80 nanofiber media
Nanofibers strongly reduce influence of electrostatics
High mechanical efficiencies
Different discharge treatments successfully passed
No loss of filter class with IPA treatment
Sub 0.1 µm KCl particles seem to have strongest influence
Soot particles virtually have no severe effect
Very reliable filtration results under any conditions!
9. Symposium Textile Filter in Chemnitz, 2008 37 Fine dust filtration for Merv 13-A applications – Filter Media
Saving energy by progressive media design ?
9. Symposium Textile Filter in Chemnitz, 2008 38 Dust holding capacity of micro and nanofiber products
500
400
300
p [Pa] p 200 Media A (Fiberglass) 100 Media B (Synthetic Microfiber) Media C (Synthetic Microfiber) 0 0 50 100 150 200
Dust holding capacity [g]
Dust holding capacity of different panel filters
Cond.: 593x593x95 mm, measurement according to EN779 (Standard), 3400 m3 h-1
9. Symposium Textile Filter in Chemnitz, 2008 39 Dust holding capacity of micro and nanofiber products
500
400
300
p [Pa] p 200 Media A (Fiberglass) 100 Media B (Synthetic Microfiber) Media C (Synthetic Microfiber) 0 Media D (Synthetic Nanofiber) 0 50 100 150 200 Dust holding capacity [g]
Dust holding capacity of different panel filters
Cond.: 593x593x95 mm, measurement according to EN 779 (Standard), 3400 m3 h-1
9. Symposium Textile Filter in Chemnitz, 2008 40 Energy demand and lifetime costs
Q p t Annual costs (operation and service) E = 1000 700
650
] € E Energy demand [kWh] 600 Q Flow rate [m3 s-1] p Pressure drop [Pa] 550 t Time [h]
Fan efficiency [-] [ costs Total 500 Total costs F7 450 Assumptions: Total costs IFN 80 400 Dust concentration: 1 g Ashrae/day Flow rate: 3400 m3 h-1 0 50 100 150 200 Energy costs: 0,15 €/kWh Operation time [d] Cost per filter: 60 €/filter Labour costs: 15 €/change
Annual Energy costs: Total costs:
Media C: 390,59 € 705,25 € Media D: 335,93 € (- 14,0 %) 562,17 € (-20,3%)
9. Symposium Textile Filter in Chemnitz, 2008 41 Nanofiber filtration for Merv 13-A applications – Filter Media
Nanofiber filter media – Washable mini pleats?
9. Symposium Textile Filter in Chemnitz, 2008 42 Nanofiber filtration for Merv 13-A applications – Washable Filter Media
100.0
75.0
50.0
25.0
Important0.3 - 0.5 µm! Efficiency Efficiency NaCl @ 500fpm 0.5-1.0 µm • Mechanical 0.0 protection of New Filter Loaded Filter 1st Washing 2nd Washing 3rd Washing nanofibers Efficiency measurements after several dust loading and washing procedures • Sufficient nanofiber Cond.: 24 x 24 x 4, 2000 cfm, ISO fine dust, washing with clear water concentraiton
9. Symposium Textile Filter in Chemnitz, 2008 43 Nanofiber filtration for Merv 13-A applications – Washable Filter Media
2.0 1.8 New Filter 1.6 Loaded Filter 1.4 1st Washing 1.2 2nd Washing 1.0 3rd Washing 0.8 0.6 0.4
Pressure Drop [inch PressureDrop [inch w.g.] 0.2 0.0 100 300 500 700 Air Flow [fpm]
Resistance measurements after several dust loading and washing procedures
Cond.: 24 x 24 x 4, 2000 cfm, ISO fine dust, washing with clear water
9. Symposium Textile Filter in Chemnitz, 2008 44 Other examples I: nanofiber filter media for high efficiency filters
High efficiency filters up to 95 DOP
•Increased nanofiber density •Coarse fibers only for stabilization •Very good mechanical stability
9. Symposium Textile Filter in Chemnitz, 2008 45 Other examples II: nanofiber filter media for prefilters ?!
0.40 350
0.35 Pressure Drop DHC 300 - 35% + 69% 0.30 250 0.25 200 0.20 150 0.15 100 0.10
0.05 50 AshraeDHC Dust @ 1.8''
Initial Resistance Resistance Initial inch w.g.@ 500fpm 0.00 0 Standard Nanofiber Standard Nanofiber
Improvement of prefilter (MERV10) by innovative media design using nanofibers
Cond.: 24 x 24 x 4, 2000 cfm, ASHRAE 52.2 and EN779 tests
9. Symposium Textile Filter in Chemnitz, 2008 46 Outline
History of Nanofibers in Filtration
Technical Characteristics of Nanofibers
Production Technologies
Performance in Filtration Applications
High Efficiency Filtration
Progressive Media Design
Examples
Summary
9. Symposium Textile Filter in Chemnitz, 2008 47 Summary and Outlook
HVAC: Nanofibers / Electrostatics / Energy Efficiency
• Push back of electrostatics by nanofibers • Washability of filters possible if nanofibers protected and mechanically stable • Improved progressivity by nanofibers for higher DHC • Enhanced energy efficieny • High and low efficiency filters with nanofibers possible
9. Symposium Textile Filter in Chemnitz, 2008 48 Nanofiber filter media - beyond filtration…
Department of Applied Art
University of Applied Science Zwickau
9. Symposium Textile Filter in Chemnitz, 2008 49
Thank you !
9. Symposium Textile Filter in Chemnitz, 2008 50