Nanofibers. New Developments in Filtration. Dr. Andreas Seeberger Mike Harriman. NAFA Technical Seminar Phoenix AZ, 2012

Transcription

1 Nanofibers New Developments in Filtration Dr. Andreas Seeberger Mike Harriman Abb.: 4, FotoNr.: 0606A00011, 1140 : 1 50 µm NAFA Technical Seminar Phoenix AZ, 2012 Abb.: 26, FotoNr.: 0606A00035, 630 : 1 50 µm 9. Symposium Textile Filter in Chemnitz, 2008

2 IREMA-FILTER and Aeolus Filter Corp. German Company Manufacturer of synthetic filter media Manufacturer of pleated products Located in Greensboro, NC Manufacturer of synthetic filters Established 1997 Synthetic Filter Media for Automotive HVAC Industry 9. Symposium Textile Filter in Chemnitz,

3 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,

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,

5 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,

6 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 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,

7 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,

8 Definition of Nanotechnology Milliscale Microscale Nanoscale Red blood cell with white cell (~ 2-5 μm) Ant (~ 5 mm) Dust Mite (~ 200 Human hair μm) (~ μm wide) cm 10 mm 1 mm 0,1 mm 100 μm 0,01 mm 10 μm Visible Spectrum 10 μm 100 nm Head of a pin (~ 1-2 mm) Micro Electro Mechanical Devices (~ μm wide) Pollen grain Red blood cells DNA (~ 1-1/2 nm) ,01 μm 10 nm 1 nm Nanofibers (~ nm) Stacks of clay mineral pletelets, each platelet with ~ 1 nm thickness Abb.: 26, FotoNr.: 0606A00035, 630 : 1 50 µm 5 Atoms of silicon (~ 1nm) ,1 nm Carbon Nanotube (~ 2 nm diameter) 9. Symposium Textile Filter in Chemnitz,

9 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,

10 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,

11 Production Technologies Manufacturing Techniques Electrospinning Meltblown Synthetic Island-In-The-Sea Glass Fiber Wet Laid Microglass Centrifuge Spinning Others 9. Symposium Textile Filter in Chemnitz,

12 Glass fibers Source: Owens 9. Symposium Corning Fiberglas Textile Corporation, Filter in Chemnitz, Journal of 2008 the Air Pollution Control Association

13 Wet-laid microglass production Distributor Web Formation Binder Application Drying Source: I. Lappas, 9. Symposium Filtrex ASIA, Textile New-Delhi Filter in 2010 Chemnitz, / / Dynatec

14 Microglass Composition Composition E -Glass C-Glas Silicon dioxide % % Calcium oxide % - Aluminium oxide % 2-6 % Boron oxide 8-13 % 2-7 % Binder Systems Latex Melamine Phenolic Epoxy Sodium and potassium oxide Mognesium oxide Magnesium oxide and calcium oxide 0-1 % 8-12 % 0-6 % % 9. Symposium Textile Filter in Chemnitz,

15 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,

16 Polymer Nanofibers Tissue engineering scaffold Adjustable biodegradation rate Better cell attachment Contraollable cell directional growth Filter media Improved performance Protective clothing Breathable fabric that blocks chemicals Cosmetics High utilization Higher transfer rate Material reinforcement Higher fracture toughness Higher delamination resistance Wound dressing Prevents scar Bacterial shielding Polymer Nanofibers Drug delivery Increased dissolution rate Drug-nanofiber interlace Medical prosthesis Lower stress concentration Higher fracture strength Heamostatic devices Higher efficiency in fluid adsorption Optical applications Liquid crystal optical shutters Electrical conductors Ultra small devices Sensor devices Higher sensitivity For celd, arteries and veins 9. Symposium Textile Filter in Chemnitz,

17 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 Narrow diameter range Nano-range not easy achievable Solvent use Two-step-process 9. Symposium Textile Filter in Chemnitz,

18 Electrospinning Advantages Fiber diameters as low as 50 nm Various polymers applicable Homogeneous fiberdiameters Disadvantages Low production rate Use of environmentally critical solvents Two-step-process Fibers only in layers 9. Symposium Textile Filter in Chemnitz,

19 Meltblown polymer air polymer fibers air spinneret hot air hot air Recently increasing R&D activities New improvements for finer fiber diameters Advantages High productivity Solvent free Single step process Disadvantages normal operation: fiber diameters of only 1-2 microns 9. Symposium Textile Filter in Chemnitz,

20 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,

21 The impact of nanofibers on filtration Decreasing pressure drop Slip Flow Effect tu f 0 p 2 d Kn r f f η = viscosity d f = diameter of the fiber t = thickness of filter U 0 = face velocity of filter α = Volume fraction of fibers in a filter fiber volume 1 porosity total volume Increasing collection efficiency High inner surface area Improved media design possibilities More distinct progressivity 9. Symposium Textile Filter in Chemnitz,

22 Filtration Markets for polymeric nanofiber products Dust Collection HVAC HEPA Filtration Automotive Vacuum Cleaners EDM Fuel Filtration Protective Clothing Battery Separator 9. Symposium Textile Filter in Chemnitz,

23 High Efficiency Synthetic Filter Media Nanofiber Product Electrete Product High efficiency products Well balanced pressure drop No or little discharge Very reliable filtration Very low initial resistance Mostly medium efficiencies Strong discharge possible 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,

24 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,

25 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,

26 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 discharge treatments Nordtest / SINTEF ASHRAE research projects RP 1189/1190 EUROVENT 2004 round robin test R&D of filter companies Still lack of information/transparency Treatment methods Superfine KCl Isopropyl alcohol (IPA) Soot Detergents 9. Symposium Textile Filter in Chemnitz,

27 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,

28 Comparison of treatments for synthetic filter media pren779:2010 ASHRAE 52.2 Appendix J Diesel soot Isopropyl alcohol (IPA)treatment to simulate discharge effects Minimum DEHS efficiencies must be reached (0.4 µ): F7: 35 % F8: 55 % F9: 70 % Conditioning step: superfine KCl (sub 0.1 µ) Loading until minimum efficiency (0.4 µ KCl) is reached Diesel soot nanoparticles treatment to investigate effects on efficiency sub 0.1 µm particles Independent Testing 9. Symposium Textile Filter in Chemnitz,

29 EN779: F7 panel filter with integrated nanofibers DEHS Efficiency [%] pren779:2010 Isopropyl alcohol (IPA) treatment to simulate discharge effects Minimum DEHS efficiencies must be reached (0.4 µ): F7: 35 % Efficiency DEHS [%] untreated F7 filter class Efficiency DEHS [%] completely Efficiency immersed DEHS [%] in IPA and untreated dried for 24 h 0, Particle Size [µm] EN779:2010 test of panel filter with IREMA IFN80 nanofiber media Cond.: 593x593x95 mm, EN779 standard test, 3400 m 3 h Symposium Textile Filter in Chemnitz,

30 Ashrae 52.2: Merv 13 panel filter with integrated nanofibers Efficiency [%] ASHRAE 52.2 Standard KCl efficiency , Particle Size [µm] Efficiency DEHS [%] untreated Efficiency DEHS [%] discharged by IPA Efficiency KCl [%] untreated Ashrae 52.2 test of panel filter with IFN80 nanofiber media Cond.: 593x593x95 mm, Ashrae Dust, 3350 m 3 h Symposium Textile Filter in Chemnitz,

31 Ashrae conditioning characteristics Counts Peak at 40 nm KCl conditioning aerosol ,001 0,01 0,1 1 Particle Size [µm] Average number distribution of ambient air particles from the Pittsburgh Air Quality Study (PAQS) Particle size distribution at Ashrae 52.2 conditioning step Atmospheric Environment 38 (2004) Symposium Textile Filter in Chemnitz,

32 Ashrae 52.2: Merv 13-A panel filter w. integrated nanofibers Efficiency [%] ASHRAE 52.2 Appendix J Conditioning step: superfine KCl (sub 0.1 µ) Loading until minimum efficiency (0.4 µ KCl) is reached No p increase during loading MERV 13-A 10 Efficiency KCl [%] 0 discharged by 0,1 1 superfine KCl 10 Particle Size [µm] Efficiency DEHS [%] untreated Efficiency DEHS [%] discharged by IPA Efficiency KCl [%] untreated Ashrae 52.2 test of panel filter with IFN80 nanofiber media including Appendix J conditioning step Cond.: 593x593x95 mm, Ashrae Dust, 3350 m 3 h Symposium Textile Filter in Chemnitz,

33 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) Symposium Textile Filter in Chemnitz,

34 Soot loadig: F7 integrated nanofiber media Particle number [10k] Efficiency [%] ,01 0 0,1 1 Particle size distribution of soot Peak at 70 nm Particle 0,1 size [µm] 1 10 Particle size [µm] Measurement of NaCl efficiency Initial Efficiency NaCl Initial efficiency KCl Initial efficiency DEHS Efficiencies of various aerosols on IREMA IFN80 nanofiber media Cond.: velocity approx m/s, efficiency measurements with NaCl and soot 9. Symposium Textile Filter in Chemnitz,

35 Soot loadig: F7 integrated nanofiber media Efficiency NaCl [%] ,01 0, Particle size [µm] No efficiency drop during soot loading seen Initial Efficiency (APS) +50 Pa soot (APS) Soot loading on IREMA IFN80 nanofiber media Cond.: velocity 0.15 m/s, efficiency measurements with NaCl 9. Symposium Textile Filter in Chemnitz,

36 Soot loadig: F7 integrated nanofiber media Efficiency NaCl [%] ,01 0, Particle size [µm] Initial Efficiency (SMPS) Initial Efficiency (APS) +50 Pa soot (SMPS) +50 Pa soot (APS) 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,

37 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,

38 Fine dust filtration for Merv 13-A applications Filter Media Saving energy by progressive media design? 9. Symposium Textile Filter in Chemnitz,

39 Dust holding capacity of micro and nanofiber products p [Pa] Dust holding capacity [g] Media A (Fiberglass) Media B (Synthetic Microfiber) Media C (Synthetic Microfiber) Dust holding capacity of different panel filters Cond.: 593x593x95 mm, measurement according to EN779 (Standard), 3400 m 3 h Symposium Textile Filter in Chemnitz,

40 Dust holding capacity of micro and nanofiber products p [Pa] Media A (Fiberglass) Media B (Synthetic Microfiber) Media C (Synthetic Microfiber) Media D (Synthetic Nanofiber) Dust holding capacity [g] Dust holding capacity of different panel filters Cond.: 593x593x95 mm, measurement according to EN 779 (Standard), 3400 m 3 h Symposium Textile Filter in Chemnitz,

41 Energy demand and lifetime costs Total costs [ ] E = Q p t Annual costs (operation and service) E Energy demand [kwh] Q Flow rate [m 3 s -1 ] p Pressure drop [Pa] t Time [h] Fan efficiency [-] Assumptions: Dust concentration: 1 g Ashrae/day Flow rate: 3400 m 3 h -1 Energy costs: 0,15 /kwh Cost per filter: 60 /filter Labour costs: 15 /change Total costs F7 Total costs IFN Operation time [d] 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,

42 Nanofiber filtration for Merv 13-A applications Filter Media Nanofiber filter media Washable mini pleats? 9. Symposium Textile Filter in Chemnitz,

43 Nanofiber filtration for Merv 13-A applications Washable Filter Media Efficiency 500 fpm Important! µm µm Mechanical 0.0 protection of New Filter Loaded Filter 1st Washing 2nd Washing 3rd Washing nanofibers Efficiency measurements after several dust loading and Sufficient washing procedures nanofiber Cond.: 24 x 24 x 4, 2000 cfm, ISO fine dust, washing with clear water concentraiton 9. Symposium Textile Filter in Chemnitz,

44 Nanofiber filtration for Merv 13-A applications Washable Filter Media Pressure Drop [inch w.g.] New Filter 1.6 Loaded Filter 1.4 1st Washing 1.2 2nd Washing 1.0 3rd Washing 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,

45 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,

46 Other examples II: nanofiber filter media for prefilters?! Initial Resistance inch 500 fpm DHC Ashrae 1.8'' Pressure Drop - 35% DHC + 69% Standard Nanofiber Standard Nanofiber 0 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,

47 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,

48 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,

49 Nanofiber filter media - beyond filtration Department of Applied Art University of Applied Science Zwickau 9. Symposium Textile Filter in Chemnitz,

50 Thank you! 9. Symposium Textile Filter in Chemnitz,