Nanoscaled Particle Size Distributions and Gas Temperatures from Time-resolved LII Measurements
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Transcript of Nanoscaled Particle Size Distributions and Gas Temperatures from Time-resolved LII Measurements
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Institut für Chemische TechnikEngler-Bunte-Institut/VerbrennungstechnikUniversität Karlsruhe (TH)
Prof. Dr.-Ing. H. Bockhorn
Dipl.-Ing. Thilo Lehre
Institut für Chemische Technik and Engler-Bunte Institut
Universität Karlsruhe
H.Bockhorn, B.Jungfleisch, T. Lehre, R. Suntz
Nanoscaled Particle Size Distributions and Gas Temperatures from
Time-resolved LII Measurements
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Institut für Chemische TechnikEngler-Bunte-Institut/VerbrennungstechnikUniversität Karlsruhe (TH)
Prof. Dr.-Ing. H. Bockhorn
Dipl.-Ing. Thilo Lehre
Motivation• Environmental: Soot emission regulations
• Modelling: Data for gas-to-particle conversion models
• Nanotechnology: Properties depend on p(r)
• Product Design: Control p(r) by varying process parameters
Experimental approach : Optical method
Non-intrusive temporally and spatially resolved in-situ characterization of particle sizes
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Institut für Chemische TechnikEngler-Bunte-Institut/VerbrennungstechnikUniversität Karlsruhe (TH)
Prof. Dr.-Ing. H. Bockhorn
Dipl.-Ing. Thilo Lehre
Diameter D63 based on
2
2
2
lnlnexp
2
1)(
mrr
rrP =
0.34
Rayleigh-Scattering: 6th Moment M6
LII: 3th Moment M3
Present Particle Sizing Technique: RAYLIX
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Institut für Chemische TechnikEngler-Bunte-Institut/VerbrennungstechnikUniversität Karlsruhe (TH)
Prof. Dr.-Ing. H. Bockhorn
Dipl.-Ing. Thilo Lehre
• Solving mass and engergy balance yields TP(t)
• Accurate description of heat / mass transport kinetics is essential
Modelling LII: Mass and Energy Balances
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Institut für Chemische TechnikEngler-Bunte-Institut/VerbrennungstechnikUniversität Karlsruhe (TH)
Prof. Dr.-Ing. H. Bockhorn
Dipl.-Ing. Thilo Lehre
Planck‘s law for a single particle:
Signal decay for particle size distribution p(r):
Assessment of p(r) and Tg: Multidimensional Nonlinear Regression
M
N
i i
Mii aavaluesfitMinaatyy
........,
1
!2
1
12
gPemem
emgP TCT
Cr
CTTrtR 3
123
61
, 1exp,,,
drTTrtRrpNtJ emgPTem ,,,,)(),(
Modelling LII: Signal Decays
yi: measured datay: model functioni: weight
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Institut für Chemische TechnikEngler-Bunte-Institut/VerbrennungstechnikUniversität Karlsruhe (TH)
Prof. Dr.-Ing. H. Bockhorn
Dipl.-Ing. Thilo Lehre
Detection of Time-Resolved LII- Signals in laminar premixed flat flame (12kPa / 1 atm)
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Institut für Chemische TechnikEngler-Bunte-Institut/VerbrennungstechnikUniversität Karlsruhe (TH)
Prof. Dr.-Ing. H. Bockhorn
Dipl.-Ing. Thilo Lehre
TEM analysis yields:
p(r) log-normal, =0.34
2,6 nm < rm < 16 nm
Na-D inversion method:
gas temperatures Tg
LII Model validation
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Institut für Chemische TechnikEngler-Bunte-Institut/VerbrennungstechnikUniversität Karlsruhe (TH)
Prof. Dr.-Ing. H. Bockhorn
Dipl.-Ing. Thilo Lehre
• Calculations agree with experiments (moderate laser fluxes)
• Assessment of p(r) and Tg from LII signals seems possible
Comparison of measured and calculated LII-signals
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Institut für Chemische TechnikEngler-Bunte-Institut/VerbrennungstechnikUniversität Karlsruhe (TH)
Prof. Dr.-Ing. H. Bockhorn
Dipl.-Ing. Thilo Lehre
Non-linear Regression: P(r) log-normal, = 0.34; rm=8.3 nm; Tg=1724 K
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Institut für Chemische TechnikEngler-Bunte-Institut/VerbrennungstechnikUniversität Karlsruhe (TH)
Prof. Dr.-Ing. H. Bockhorn
Dipl.-Ing. Thilo Lehre
Model Uncertainties during LASER pulse due to Absorption kinetics Heat/mass transfer kinetics ???
Excitation curves in atmospheric laminar premixed flat flame:
Model and Measurements
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Institut für Chemische TechnikEngler-Bunte-Institut/VerbrennungstechnikUniversität Karlsruhe (TH)
Prof. Dr.-Ing. H. Bockhorn
Dipl.-Ing. Thilo Lehre
Particle Temperature Measurements : 2 colour LII
12
215
2
1
12
ln
11
I
IK
khc
T
cal
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Institut für Chemische TechnikEngler-Bunte-Institut/VerbrennungstechnikUniversität Karlsruhe (TH)
Prof. Dr.-Ing. H. Bockhorn
Dipl.-Ing. Thilo Lehre
1D + time resolved 2 colour LII in laminar atmospheric premixed flat flame
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Institut für Chemische TechnikEngler-Bunte-Institut/VerbrennungstechnikUniversität Karlsruhe (TH)
Prof. Dr.-Ing. H. Bockhorn
Dipl.-Ing. Thilo Lehre
Additional Measurements in atmospheric laminar premixed flat flame
Particle diameter:
RAYLIX
Flame temperature:
2 colour pyrometry
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Institut für Chemische TechnikEngler-Bunte-Institut/VerbrennungstechnikUniversität Karlsruhe (TH)
Prof. Dr.-Ing. H. Bockhorn
Dipl.-Ing. Thilo Lehre
Input to calculated T(t): measured TP(15ns after pulse); no absorption model
p(r) and Tg from independant measurements
Validation of heat/mass transfer kinetics
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Institut für Chemische TechnikEngler-Bunte-Institut/VerbrennungstechnikUniversität Karlsruhe (TH)
Prof. Dr.-Ing. H. Bockhorn
Dipl.-Ing. Thilo Lehre
Advantages of 2 colour LII
• Modelling LII during Laser pulse not required
• Modelling superheating not required
• Independance of refractive index (grey bodies)
• Experimental value for laser fluence not required
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Institut für Chemische TechnikEngler-Bunte-Institut/VerbrennungstechnikUniversität Karlsruhe (TH)
Prof. Dr.-Ing. H. Bockhorn
Dipl.-Ing. Thilo Lehre
rt
tTtT
exp0
iri
tptTtT
exp0
monodisperse size distribution
lognormal size distribution
Nonlinear Regression
Fit parameters: rm ,
Fit function: TP(t)
Result: Flat minimum
region = a rm + b
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Institut für Chemische TechnikEngler-Bunte-Institut/VerbrennungstechnikUniversität Karlsruhe (TH)
Prof. Dr.-Ing. H. Bockhorn
Dipl.-Ing. Thilo Lehre
Low time resolution has no effect on measured particle temperatures ( 2 colour LII ) for t > 20ns
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Institut für Chemische TechnikEngler-Bunte-Institut/VerbrennungstechnikUniversität Karlsruhe (TH)
Prof. Dr.-Ing. H. Bockhorn
Dipl.-Ing. Thilo Lehre
Nonlinear Regression: Fit parameters: rm , Fit function: TP(20ns) –TP ( 1000ns)
Unique minimum along = a rm + bexists
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Institut für Chemische TechnikEngler-Bunte-Institut/VerbrennungstechnikUniversität Karlsruhe (TH)
Prof. Dr.-Ing. H. Bockhorn
Dipl.-Ing. Thilo Lehre
lognormal =0.34:rm = 5nm
monodisperse: rm = 10nm
Sensitivity to rm for a given shape of p(r)
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Institut für Chemische TechnikEngler-Bunte-Institut/VerbrennungstechnikUniversität Karlsruhe (TH)
Prof. Dr.-Ing. H. Bockhorn
Dipl.-Ing. Thilo Lehre
Sensitivity of 2 colour LII to p(r)
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Institut für Chemische TechnikEngler-Bunte-Institut/VerbrennungstechnikUniversität Karlsruhe (TH)
Prof. Dr.-Ing. H. Bockhorn
Dipl.-Ing. Thilo Lehre
23
3
6
2
27exp
)(
)(barr
drrpr
drrprKS mmR
barrf mm )(
Time-resolved LII:
RAYLIX:
Particle Size Distributions from Scattering + LII
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Institut für Chemische TechnikEngler-Bunte-Institut/VerbrennungstechnikUniversität Karlsruhe (TH)
Prof. Dr.-Ing. H. Bockhorn
Dipl.-Ing. Thilo Lehre
Summary• LII model validation in sooting laminar premixed
flames (1 bar; 0.12bar)
• Heat/mass transfer kinetics validation based on
particle temperature measurements
• Assessment of p(r) and Tg from LII / 2 colour LII
using Multi - D- nonlinear regression
• Time range>1us gives good sensitivity to p(r)
• Simultaneous detection of scattering increases
sensitivity to p(r)
• Outlook: P(r) in laminar diffusion flame
space
time