relationship between threshold soot index and...
TRANSCRIPT
Relationship between Threshold Soot Index and Soot Levels for Surrogate Fuels
Venkatesh Iyer, Suresh Iyer, Milton Linevsky, Thomas Litzinger, and Robert Santoro
The Pennsylvania State University, University Park, PA 16802
Smoke point measurement is required for characterization of jet fuels
• Smoke Point = maximum height of a smoke free laminar diffusion flame
Increasing fuel flow
Smoke Point
Up to smoke point:
Production = Oxidation
Above smoke point:
Production > Oxidation
Kent and Wagner, 1984 Z = z (D/Q)
Calcote and Manos created Threshold Soot Index (TSI) to correlate smoke point data
SP = smoke point heightMW = molecular weighta & b = constants dependent on the experiment.
bSP
MWaTSI +⎟⎠⎞
⎜⎝⎛=
Linear behavior of TSI for mixtures facilitates matching of surrogate to actual fuels
R2 = 0.9775
0
2
4
6
8
10
12
14
16
0 0.2 0.4 0.6 0.8 1Iso-octane mole fraction
MW
/Sm
oke
Poi
nt
Calibration of Smoke Point apparatus is done with mixture of iso-octane and toluene
Peak Centerline Soot fv vs. TSI (Olson et al., 1985)
n-propylbenzene
1,3,5-trimethylbenzene
Wick burner for studies of soot fields of surrogates and jet fuels
Inner tubeOuter tube
Ceramic honeycomb
3mm glass beads
ASTM Standard wick
Translation stage
Soot measured with light extinction
Fuel Matrix for Wick Burner Studies
Smoke Height ASTM Burner
(mm)
TSI ASTM Burner
H/C ratio
Jet A (4658) 22.1 21.4 1.957
2nd generation surrogate
22.5 20.4 1.95
D95 38.5 13.9 2.1*
JP8 (5699) 23 22.3 1.935
D95 + toluene 23 21.7 1.913
*estimated
Exxsol D95: Narrow cut (C12-C16), de-aromatized solvent
Carter et.al. (2000)
15.0 20.0 25.0 30.0 35.0
n-C12
n-C13
n-C14
n-C15
iso-C13
iso-C14
15.0 20.0 25.0 30.0 35.0
n-C12
n-C13
n-C14
n-C15
iso-C13
iso-C14
Approximate composition
Normal paraffins 23%
Iso-paraffins 33%
Cyclo-paraffins 44%
Fuel Matrix for Wick Burner Studies
Smoke Height ASTM Burner
(mm)
TSI ASTM Burner
H/C ratio
Jet A (4658) 22.1 21.4 1.957
2nd generation surrogate
22.5 20.4 1.95
D95 38.5 13.9 2.1*
JP8 (5699) 23 22.3 1.935
D95 + toluene 23 21.7 1.913
*estimated
10mm height
12.5mm height
Soot volume fractions distribution:Jet A (4658) and MURI 2nd generation surrogate
2nd gen. surrogateJet A (4658)
Fuel Matrix for Wick Burner Studies
Smoke Height ASTM Burner
(mm)
TSI ASTM Burner
H/C ratio
Jet A (4658) 22.1 21.4 1.957
2nd generation surrogate
22.5 20.4 1.95
D95 38.5 13.9 2.1*
JP8 (5699) 23 22.3 1.935
D95 + toluene 23 21.7 1.913
*estimated
Soot volume fractions distribution:JP8 (5699) and D95 – Toluene surrogate
D95-TolueneJP8 (5699)
5mm height
7.5mm height
Soot volume fractions distribution:JP8 (5699) and D95 – Toluene surrogate
D95-TolueneJP8 (5699)
10mm height
12.5mm height
Soot volume fractions distribution:JP8 (5699) and D95 – Toluene surrogate
D95-TolueneJP8 (5699)
15mm height
17.5mm height
TSI Summary• Jet A (4658) / 2nd generation surrogate
– Different smoke heights on the wick burner: 21mm v 23 mm– Similar peak volume fractions– Different radial soot profiles: offset axially by ~2mm
• JP8 (5699) / D95 + Toluene surrogate– Same smoke heights on the wick burner– Similar peak volume fractions– Similar radial soot profiles
Comparison of Surrogate and JP8 in Dump Combustor
Dump Combustor
Optical access --soot via light extinction
Fuels for Dump Combustor Study
Smoke Height ASTM Burner
TSI ASTM Burner
H/C ratio
JP8 (5699) 23 22.3 1.935
D95 + toluene 23 21.7 1.913
2nd generation surrogate is too expensive to run in these experiments
19
P=5 atm
Inlet T=510K
Possible causes of difference in soot levels for JP8 and surrogate
• H/C ratio
• Soot production from toluene compared to larger alkyl aromatics
• Differences in physical properties
What next?
• Soot production in dump combustor– Understand difference between D95 surrogate and
JP8– Studies of next gen surrogates
• Soot fields in wick burner flames– Understand different behavior of D95 surrogate and
2nd generation surrogate– Understand differences in peak fv, soot formation and
oxidation rates among aromatic compounds
Penn State teaming with Innosense, LLC to design rapid smoke point apparatus (Army STTR A10a-T010)