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18 October 2010 1
A Brief on Aerosol Mechanics
Caner U. YurteriTUDelft
18 October 2010 2
References on Aerosol Science and Technology
Fuchs, N.A., The Mechanics of Aerosols, Pergamon, Oxford, 1964. (Republished, Dover Press 1989.)
Davies, C.N. (Ed.), Aerosol Science, Academic Press, New York, 1966.
Reist, P.C., Aerosol Science and Technology, Seond Edition, McGraw-Hill, New York, 1993.
Hinds, W.C., Aerosol Technology: Properties, Behavior, and Measurement of Airborne Particles, Second Edition, Wiley, New York, 1999.
Friedlander, S.K., Smoke, Dust and Haze, Second Edition, Wiley, New York, 2000.
Baron, P. and Willeke, K., Aerosol Measurement, Second Edition, Wiley, New York, 2001.
.
Most of the pictures are taken from book of Hinds
I also like to acknowledge Dr. CY Wu of University of Florida,
and JCM Marijnissen of TUDelft for letting me use some of their lecture slides.
18 October 2010 3
• Aerosol – A suspension of particles in a gas• Particles are either solid or liquid• Suspender/carrier is usually air
• An Aerosol is a two-phase system• Particles plus the suspending gas
A giant Aerosol?...............
What is an aerosol?
18 October 2010 4
4
Aerosols in Daily Life• Air Pollution• Visibility• Stack Emission• Cloud, rain, mist• …etc
18 October 2010 5
18 October 2010 6
6
• Aerosols in manufacturing– Pigment– Sensors– Cosmetics– Optical Fiber– Solar panels– Magnetic powder– Pharmaceutical– Solid lubricant– Tires– …etc
18 October 2010 7
7
• Aerosols for Health– Interaction w/ inhalation system– Method of drug delivery– Work place, highways, animal
farms, papermill, mining, pesticide, welding, paint fume
– Way of disease transmission
Welding
18 October 2010 8
Microscopic Level Properties of Particle
• Size (nm, μm)• Particle size relative to gas mean path
• Shape• Standard Shape is a Sphere
• Density (kg/m3)• Standard Density is 1000 kg/m3
18 October 2010 9
• Equivalent sizes
– Martin’s diameter:
– Feret’s diameter:
– Projected area diameter
– Aerodynamic diameter
– …etc
What is the particle size?
18 October 2010 10
18 October 2010 11
Single Particle MotionOne need to know how to control particle movement in the air!
• For measurements• For delivery• For control
• Steady, straight line motion in response to a constant external force• Most common type of motion• Settling is prototype• Easiest to analyze
• Common because of rapid velocity adjustment
18 October 2010 12
F V d forD p 3 10 Re .
Stokes’ Law (neglecting slip correction) negligible inertial force compared to viscous force in a laminar flow for a spherical particle.Assume : Incompressible flow, Constant motion, Rigid sphere
whereV d
kg m at CPa s at C
p
12 2018 10 20
3
5
Re
. /.
Steady Particle Motion
pDC
Re24
18 October 2010 13
• Newton’s Resistance Law – Valid for High Re (negligible viscous force)• The force is proportional to the gas pushed away and the relative velocity
between the sphere and the gas
Vddtdm
pg2
4
22
8VdCF pgDD
CD = 0.44 (sphere) for 103 < Rep < 2×105
Transition Regime
6Re
1Re24 3/2
p
pDC
18 October 2010 14
FD
FG
F FD G
F mgd
gG p 3
6
V dd
gp 3
36
Settling Velocity
BVF d
d mD p
p 1
31
for V
d gTS
p
2
18
V F BTS G
18 October 2010 15
Cd
for d mC 12 52
01.
.
Cunningham Slip Correction Factor:gas velocity at the surface of small particles is not zero --> slip
At standard conditions:Mean free path
λ = 0.066 µmCc for 1.0 µm = 1.15Cc for 0.1 µm = 2.89
Cd
dC
1 2 34 105
0 39. . exp
.
↑ in ↑ CC
λ 1/ρg T 1/p
Cc if TCc if p
d< 0.1um
18 October 2010 16
Vd g C
TSp C
2
18
Settling Velocity with Slip Correction
Drag Force with Slip Correction
FVd
CDC
3
18 October 2010 17
Shape Correction - Nonspherical Particles• Shape factor: the ratio of the actual resistance force of
the nonspherical particle to the resistance force of a sphere having the same volume and velocity
• Drag force
• Settling velocity
F
VdD
e3
F VdD e 3
Vd g
TSp e
2
18
de: equivalent volume diameter
18 October 2010 18
18 October 2010 19
for spheres 0/a p pd d
20( )18
aTS
d gV
where
30 1000 /kg m
aerodynamic diameter, da
Aerodynamic Equivalent Diameter
3
8.6
1000 /a
p
d m
kg m
18 October 2010 20
Particle Acceleration• Newton’s law
)1()(
)()(
)()(3
/
tTS
pDG
eVtVdt
tdVtVgdt
tdVmdtVmgFF
FG=mg
t=0V(t)=0
FG=mg
t=V(t)=0.63VTS
FG=mg
t>3V(t)=VTS
FD=3V(t)dp
FD=3VTSdp
= mB : relaxation time
mB2
18p cd c
TSV gRelaxation Time =
18 October 2010 21
Stopping Distance
1) Re(for 6
Rearctan6Re
1) Re(for
0
3/103/1
0
000
g
pp dS
BmVVS
Time for unit density particles to reach their terminal velocitydp (m) 3 (ms) S* (cm)
0.01 0.00002 6.810-6 0.1 0.00026 8.810-5
1 0.011 3.610-3 10 0.85 0.23
100 65 12.7
* V0=1000 cm/s
d C Vp p C
20
18
18 October 2010 22
LHVV
x
TS
Horizontal Elutriator (settling chamber, spectrometer)
Unique location of deposition for each size bin……
18 October 2010 23
Inertial Impaction – Inertial sizing and seperation• Stokes number: the ratio of the stopping distance of a
particle to a characteristic dimension of the obstacle
• For an impactor
StkSd
Udc c
0
j
cpp
j
DUCd
DUStk
9
2/
2
f(Stk) efficiencyImpaction
Dj
Acceleration of Air flow
Cross sectional view of impactor
18 October 2010 24
h’
Assume :
Streamlines are arcs of a circle
Flow is uniform at exit of nozzle
Mean radius is ‘r’
Consider as a centrifuge during bending
18 October 2010 25
Determine dp50
impactorjet r rectangula afor 9
impactorjet round afor 4
9
9
502
503
5050
QLStkW
QStkD
UStkD
Cd
p
p
j
p
jcp
Impactor Cutoff
Q V A V Dj j j 2 4/
18 October 2010 26
Impactor type Stk50 Stk50 Circular nozzle 0.24 0.49 Rectangular nozzle 0.59 0.77
500 < Re (nozzle throat) < 3000 and h'/Dj > 1.5
Stk50 for 2 impactors
(√Stk ≡ dimensionless diameter)
18 October 2010 27
> 10 µm
5 – 10 µm
2 – 5 µm
< 2 µm
d50 = 10 µm
d50 = 5 µm
d50 = 2 µm
Mass Fraction/μ
m
/ad m1 2 3 4
1
3
2
4
18 October 2010 28
Virtual Impactor
18 October 2010 29
Centrifuge Separator
Cheng et al., 1988
18 October 2010 30
Used for particle size distribution measurements
AEROSOL CENTRIFUGE (another method of seperation using Inertia)
18 October 2010 31
18 October 2010 32
J DdNdx
Fick’s Law of Diffusion
D Diffusion CoefficientkTC
dC
p
3
J = Flux density (particles/Cm^2.s)
N = Number concentration
dN/dx = Concentration gradient
Einstein demonstrated that D=kTB
And = mean square particle displacementDtx 2
18 October 2010 33
Spread of particles over time and space
Numbers on curves are values of Dt
11
1/2
1/16
Dtx 2
18 October 2010 34
U
N1
2R
L
U
N2
Consider a channel where aerosol flowing through it
Main flow + Brownian Diffusion
Some particles are removed due to diffusion
Transit time of air = L/U
For particle x(rms)=sqrt(2Dt)=sqrt(2DL/U) DL/UR^2
If x(rms) << R then N2~N1 small diffusion loss <<1
If x(rms) >> R then N2/N1<<1 significant particle loss >>1
Design diffusion battery to separate particles!
18 October 2010 35
18 October 2010 36
Where e is the charge on one electron, 1.6 × 10-19 Cand E is the field strength = potential gradient
Where e is the charge on one electron, 1.6 × 10-19 Cand E is the field strength = potential gradient
F qE neEE Electrostatic Force
••Electrical PropertiesElectrical Properties
221
rqqKF EE •Coulomb’s law
18 October 2010 37
Electrical Mobility
qEBd
qECVp
cTE
3
c
TEp
CVd
qE3
(force balance)
qBd
qCE
VZp
cTE 3
(for Re < 1)
Charging MechanismsFlame Charging, Static Electrification, Spray electrification, Diffusion Charging, Field Charging
••Electrical PropertiesElectrical Properties
Terminal velocity in an electrical field
Ability of a particle to move in a E field
18 October 2010 38
••Electrical PropertiesElectrical Properties
Equilibrium (Boltzmann) Charge Distribution
kTden
kTdef
ppn
22
exp
dp Average % of particles carrying the indicated number of charges(m) Charges < -3 -3 - 2 -1 0 +1 + 2 + 3 > +30.01 0.007 0.3 99.3 0.30.02 0.104 5.2 89.6 5.20.05 0.411 0.6 19.3 60.2 19.3 0.60.1 0.672 0.3 4.4 24.1 42.6 24.1 4.4 0.30.2 1.00 0.3 2.3 9.6 22.6 30.1 22.6 9.6 2.3 0.30.5 1.64 4.6 6.8 12.1 17.0 19.0 17.0 12.1 6.8 4.61.0 2.34 11.8 8.1 10.7 12.7 13.5 12.7 10.7 8.1 11.82.0 3.33 20.1 7.4 8.5 9.3 9.5 9.3 8.5 7.4 20.15.0 5.28 29.8 5.4 5.8 6.0 6.0 6.0 5.8 5.4 29.810.0 7.47 35.4 4.0 4.2 4.2 4.3 4.2 4.2 4.0 35.4
tNeZntn ii4exp)( 0
Number of charges on a particle after it has been exposed to a bipolar ion concentration
(dp > 0.05 m)
18 October 2010 39
Diffusion Charging• Random collisions between ions and particles
• No external electrical field needed; • independent of materials
kTtNecd
ekTd
q iipp
2
1ln2
2
Total charge
STP) @ cm/s 10(2.4
speed lion thermamean 4
ic
Ni: ion concentration
18 October 2010 40
Field Charging• Bombardment of ions in the presence of a
strong field
4
23 2
ps
Edq
Saturation charge
tNtNEd
qi
ip
i
i2
eZ 1eZ
4
23
Charges by field charging
Zi: ion mobility (450 cm2/stVs): dielectric constant
18 October 2010 41
Corona Discharge• Field strength inside
a cylinder
EV
r d dt w
ln( / )
Edb
w
3012 7.
Breakdown field strength (kV/cm)
dw: wire diameter (cm)dt: tube diameter (cm)
18 October 2010 42
Comparison of Diffusion & Field Chargingdp (um) ndiff nfield ntotal Zdiff ZField Z (stC•s/g)
0.01 0.10 0.02 0.12 0.66 0.10 0.760.02 0.30 0.06 0.36 0.49 0.11 0.600.05 1.1 0.40 1.50 0.31 0.12 0.430.1 2.8 1.6 4.38 0.23 0.13 0.360.2 7 6.5 13.2 0.18 0.17 0.350.5 21 40 61.2 0.15 0.30 0.451 48 161 209 0.16 0.52 0.682 108 646 754 0.16 0.98 1.145 311 4035 4346 0.18 2.34 2.5210 683 16140 16824 0.20 4.61 4.8020 1490 64562 66052 0.21 9.16 9.3750 4134 403510 407644 0.23 22.78 23.0
Number of Charges vs dp
dp (um)0.01 0.1 1 10
n
10-2
10-1
100
101
102
103
104
105
106
Diffusion chargingField Charging
Nit = 107 s/cm3
= 5.1E = 5 KV/cmT = 298 K
18 October 2010 43
Charge Limits• Solid particles
• Liquid droplet: Rayleigh limit
2
32e
dn p
L
nd E
eLp L2
4 charged positivelyfor stV/cm 107 charged negativelyfor stV/cm 103
5
4
LE
18 October 2010 44
Electrical Measurement: Electrical Mobility Analyzer
VLUhZ pL
22 V: potential difference between plates
U: mean flow velocityh: half the inter-plate distanceL: inlet to exit distance
hVE2
U
18 October 2010 45
18 October 2010 46
18 October 2010 47
Electrical MeasurementEAA (Electrical Aerosol Analyzer) DMA (Differential Mobility Analyzer)
18 October 2010 48
Time of Flight
18 October 2010 49
18 October 2010 50
Particle InletParticle InletPMT PMT DSPDSP
PCPC
Scattered lightScattered light
EE--SPART AnalyzerSPART AnalyzerElectronic Single Particle Electronic Single Particle Relaxation Time AnalyzerRelaxation Time Analyzer
Laser beamsLaser beams
AC electrodeAC electrode AC electrodeAC electrode
18 October 2010 51
Comparison of PSDs of 3 Different Mannitol Samples
Aerodynamic Diameter, µm
% C
umul
ativ
e C
ount
0
20
40
60
80
100
1.0 2.5 5.0 7.5 10.0 25.0 50.0
Mannitol 1,CMD=5.08µm,MMD=16.00µmMannitol 2,CMD=6.14µm,MMD=13.89µmMannitol 3,CMD=7.59µm,MMD=15.03µm
12
3
-80.00%
-60.00%
-40.00%
-20.00%
0.00%
20.00%
40.00%
60.00%
80.00%
Mannitol 3 Mannitol 5 Mannitol 7-v
e Q
/M
% M
ass
+v
e Q
/M
PSD of the Mannitol PSD of the Mannitol --1, 1, --2 and 2 and --3 powders3 powders
measuredmeasuredBy EBy E--SPARTSPART
Bipolar charging of the Mannitol Bipolar charging of the Mannitol --1, 1, --2 2 and and --3 powders. Sum of the positive and 3 powders. Sum of the positive and
negative charge mass fraction negative charge mass fraction subtracted from 100% provide neutral subtracted from 100% provide neutral mass fraction. (Size range 0 to 33 mass fraction. (Size range 0 to 33 µµm)m)
18 October 2010 52
52
Production of Test Aerosols
• monodisperse, • Stable and reproducable, • Uncharged or charged, • solid at the final stage,• spherical in shape with size and concentration control.
•Via breaking up of bulk liquids
•Via evaporation and condensation
•Via dispersion of fine powders
18 October 2010 53
53
Atomization of Liquids
3/1Fdd ds
Mass conc. of 5-50 g/m3
1-10 m g of 1.5-2.2
Liquid Solution Suspension
18 October 2010 54
54
Ultrasonic Nebulizer
3/1
2
fCMD
L
18 October 2010 55
55
3/16
fQd L
p
Vibrating Orifice Aerosol Generator (VOAG)
18 October 2010 56
56
Spinning Disc Aerosol Generator
Rd
Ld
47.0
18 October 2010 57
57
3/16
NCd
L
md
Condensation Aerosol Generator
Basic principle to generate monodisperse aerosol: allow condensation to occur under slow and controlled condition
18 October 2010 58
58
Atomization of Liquid SuspensionLiquid suspension containing monodisperse solid particles of known size
3
where exp!
)(
p
dn
ddFxx
nxnP
18 October 2010 59
2010/10/18 Aerosol & Particulate Research Laboratory 59
2.1 GSD and 0.9for
)exp(ln5.01ln5.4exp)1(
23
23
R
GSDMMDGSDdR
F p
(R: ratio of singlets to droplets containing particles)
Considering the size distribution of droplets …..
18 October 2010 60
60
Dispersion of Powders
Requirement:a means to continuously
metering a powder into the generator at a constant rate
a means to dispersingthe powder
Common methods:High velocity air streamScraperFluidized bed generator
Wright Dust Feeder
18 October 2010 61
61
Dispersibility depends on:Powder materialParticle sizeShapeMoisture content
Fluidized Bed Aerosol Generator
18 October 2010 62
Caner U. YurteriDelft University of Technology, The Netherlands
EHDA for
PRODUCTION of Micro & NANO PHARMACEUTICAL PARTICLES
18 October 2010 63
Chemical formulation probably made in bulk liquid
formation of nanoparticlesfrom solids: grinding
lithography /etchingin liquid: colloidsin the gas phase: Atomization
solids: not consideredcolloids: contamination with surfactantsatomization of solution
Application of “GOOD”” aerosols in medicine (nano) particlesfor administration by inhalation, implantation or other way
18 October 2010 64
SOLUTION
atomization
DROPLETS
evaporation
(reaction (pyrolysis))
FINAL PRODUCT
POWDER
Production of particles from
Building up(gas or vapour molecules)
Breaking down structure(solid or liquid)
For complex and delicate pharmaceutical chemical
compounds, atomization of solution is suitable
18 October 2010 65
Atomization(disintegrating a liquid into airborne droplets)
Different atomization methods exist. For the production of mono-sized, nanoparticles with a desired
structure (e.g. solid), many restrictions exists.
- Minimum orifice size: clogging, pressure drop
- Concentration restriction
dpart ~ (precursor volume concentration)⅓
Also: impurities (e.g. mat. leaching out of syringe)
Drying difficult, e.g., porous or hollow particles
very pure
nano
Particles (narrow) size distribution
desired structure (solid, porous, …)
no multiplets
ELECTROSPRAYING
18 October 2010 66
TYPICAL Nozzle to Plate ELECTROSPRAY SYSTEM
A
B
C
D
E
18 October 2010 67
0.7 mm
Dripping spindle intermittent cone-jet multi-jet
18 October 2010 68
(varicose) (kink)
0.7 mm Scaling of droplet size and currentEHDA cone-jet modeFor the current scaling for liquids with a flat
radial velocity profile in the jet
21
)KQ(bI The droplet diameter for the varicose break-
up mode is61
2
40
v,d IQcd
Substituting equation 1 into equation 2 yields:
61
30
v,d KQ16d
Hartman et al, J. Aerosol Sci. 30(7) & Hartman et al, J. Aerosol Sci. 31(1)
18 October 2010 69
18 October 2010 70
1 10 6 1 10 5 1 10 4 1 10 3 0.010
2 10 5
4 10 5
6 10 5
8 10 5Droplet diameters based on Varicose and Kink breakup
Conductivity
Dro
plet
Dia
met
er
6.135 10 5
2.848 10 6
dk KQ0
Q1
d KQ0
Q1
10 210 6 K
0.00E+00
5.00E-06
1.00E-05
1.50E-05
2.00E-05
2.50E-05
3.00E-05
3.50E-05
4.00E-05
4.50E-05
0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00
Q, ml/h
d, m
dv, m dk, m
Droplet size in Varicose and Kink Break up as a function of Q
18 October 2010 71
1 10 6 1 10 5 1 10 4 1 10 3 0.010
1 10 5
2 10 5
3 10 5
4 10 5
Droplet diameters for different flow rates
Conductivity
Dro
plet
size
50 10 6
0
d KQ0
100 Q0
d KQ0
10 Q( )0
d KQ0
Q0
10 210 6 K
Droplet Size as a function of Q and K
0.00E+00
2.00E-05
4.00E-05
6.00E-05
8.00E-05
1.00E-04
1.20E-04
1.40E-04
1.00E-06 5.10E-05 1.01E-04 1.51E-04 2.01E-04K, S/m
d, m
0.03 ml/h 0.3 ml/h 3ml/h
Q
18 October 2010 72
Scaling of droplet size and currentEHDA cone-jet mode
For the current scaling for liquids with a flat radial velocity profile in the jet21
)KQ(bI
The droplet diameter for the varicose break-up mode is
61
2
40
v,d IQcd
Substituting equation 1 into equation 2 yields:
61
30
v,d KQ16d
18 October 2010 73
MAKING NANO AND MICRO POWDERS
18 October 2010 74
A
B
C
D
E
A
B
C
D
E
SnO2 nanoparticlescapillary-plate method
18 October 2010 75
Pt nanoparticles capillary-plate method
10 min @ 700 °C
A
B
C
D
E
A
B
C
D
E
18 October 2010 76
Nanoparticles aerosol reactor(example: platinum particles)
Neutralization
Van Erven, Moerman, Marijnissen, Aerosol Science and Technology 39 (10), 2005
18 October 2010 77
Paclitaxel (C47H51NO14) - “TAXOL”
Taxol
Polyvinylpyrrolidone (PVP) – MW 1300000 – K85-95
18 October 2010 78
Controlled release
18 October 2010 79
Hollow and spongy particles
18 October 2010 80
Thin layersThin layers
Uniform Thin Layer Coatings with Different MorphologiesSEMs of CaP Coatings
Leeuwenburgh et al., Morphology of calcium phosphate coatingsfor biomedical applications deposited using Electrostatic Spray Deposition,Thin Solid Films 503 (2006) 69–78
18 October 2010 81
Particles produced with the polymer, dichloromethane, acetone solution at a flow rate of 3ml/hr, with supply of an air flow
What about shapes?
R. Hartman, PhD thesis, 1999
E.Herben, MSc thesis, 2006
A. Salvatella, MSc thesis, 2006
Electrospun nanotubes obtained from co-spinning olive oil / PVP-Ti(OiPr)4
18 October 2010 82
A C A C
B B
+ -
Not mixed coated new mixed
18 October 2010 83
Neutralization
Bipolar Coagulation also used for neutralization
18 October 2010 84
Nanoparticles in or on carrier
LiquidSuspension
Liquid carrierprecursor
+ -
Carrier
Nanoparticles
Or
P. Coppens, M.Sc. Thesis, 2007
A or/and B can be a suspension of nano(medicine)particles
18 October 2010
Vermelding onderdeel organisatie
85
Salbutamol Microparticles
18 October 2010 86
DEPOSITING NANO AND MICRO POWDERS
ON MEDICAL SUBSTRATES
18 October 2010 87
Courtesy of Terronics
2mm
18 October 2010 88Marijnissen, J. C. M., Yurteri, C. U., van Erven, J., and Ciach, T. (2008). "Medicine Nanoparticle Production by EHDA.“ Proceedings of Workshop on Environmental and Medical Aerosol nanoparticles and their interaction with the respiratory system, L. G. a. J. Marijnissen, ed., Springer, Warshaw.
UNIFORM DEPOSITION via EHDA
- Example –
EHDA Dispersed nano particles on micro particles
NanoNano DispersionDispersion
18 October 2010 89
A Schematic representation of the Grounded moving target (GMT) set-up
(a) (b)
MSc thesis, M. Dabwoski, 2006 TUDelft
18 October 2010 90
Schematic Representation of Falling Curtain Setup
200 m glass with 500 nm PS
MSc thesis, P. Coppens, 2007 TUDelft
18 October 2010 91
Lactose coated with Bovine Serum Albuminby electrospraying a solution of the protein in ethanol and acetic acid
20 m
Work by Denise Harkema
Lactose activation by Electrospraying for Dry Powder Inhalers - Apr. 28 by Ruud Van Ommen
18 October 2010 92
For the production of medicine powders up-scaling of the method is needed.
However:Diameter of particle is function of Q
So impossible to increase Q !!!
Use parallel spray system: Out-scaling
Requirements:Electric field strength and flow rate must be equal for each sprayer
18 October 2010 93
J. Aerosol Sci. Vol. 30, No. 7, pp. 969 - 971, 1999, Multiple jet electrhydrodynamic spraying and applications by J. C. Almekinders and C. Jones
• 15 cm wide multiple jet EHDA nozzle with 24 serrations• serrations with 1.5 mm spacing is possible • operating potential 35 kV• liquid throughput ranging from 60 ml/h up to 2000 ml/h• liquids with wide range of viscosities.• polydisperse droplets
• Simple orifices instead of needles canbe used to atomize liquids in steadycone-jet mode.
• Stable operation is promoted by usingdielectric materials with hydrophobicsurfaces
• Poly-Ether-Ether-Ketone, PEEK is used as material.
• Equal narrow tubes are glued on reservoir side
• The extractor is a metallic thin platelocated parallel to the surface of
emitters
Aerosol Science 36 (2005) 1387–1399 Multiple electrosprays emitted from an array of holes R. Bocanegraa, D. Galána, M. Márquezb,c, I.G. Loscertales, A. Barrero.
18 October 2010 94
• Each electrospray is isolated with local chambers
• Droplets are discharged using oppositely charged uniformly distributed ions
• Inter nozzle spacing and nozzle to plate distance limit the design
• If nozzle to plate distance is reduced then inter nozzle spacing can be reduced by the same factor
• Multiple sprayer worked fine, however, increased particle concentration enhanced agglomeration
200 MΩ
Electrode ID5 mm
Electrode to Counter10 and 15 mm
Inter nozzle spacing50 to 100 mm
Hole size37 mm
Ionization Chamber44 needle in 50 x 10 cm^2 area
Electrohydrodynamic Atomization in Cone Jet Mode, 1998, R. Hartman, TUDelft PhD Thesis
18 October 2010 95
Circular Symmetry Design of Multi-Nozzle Electrospray in Cone-Jet Mode
Increases throughput due to usage of multiple nozzles Eliminates the influence of edge effects Facilitates uniform flow distribution No wetting problems!
Reservoir
Extractor plate
Inflow-Ethanol
Improved Design of Multi-Electrospray Unit with a Circular Symmetry: Use of Multi-Nozzle For High Throughput, Monodispersed Droplets Production – Yonsuang et al. 2010 Partec
18 October 2010 96
Thank you for your attention
And
????
