Ignition delay time measurements of LNG mixtures · Experiment to determine the ignition delay time...
Transcript of Ignition delay time measurements of LNG mixtures · Experiment to determine the ignition delay time...
Ignition delay time measurements
of LNG mixtures
Kai Moshammer
LNG II – Training Day
22.08.2017
Chemical details of combustion and ignition
processes
Rapid Compression Machine facility at PTB
Results from LNG II
Outlook into LNG III
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Outline
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Engine combustion – A complicated process
Combustion in an engine is a combination of complex physical and chemical
processes
Chemical reactions
Fluid
dynamics
Mixing and evaporation
processes
Heat transfer
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Engine combustion includes chemistry
N.N. Semenov (1896-1986)
Chemistry Nobel, 1956
Some problems relating to chain reactions and to the theory of combustion
... but it can explain the formation of unwanted byproducts or auto-ignition (knocking).
You don’t need to know much chemistry to build an engine…
N.A. Otto R.C.K. Diesel (1832-1891) (1858 –1913)
CxHy + (x+y/4) O2
⇅
x CO2 + y/2 H2O + E
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Molecular structure dictates global
combustion properties
RDX
Cyclohexane
THF
Furan
Benzene
Sooti
ng t
endency
Knockin
g t
endency
No C-C bonds
(zero soot)
Aromatic
(high soot)
CH2CH2
CH2CH3CH2
CH2CH3
CH2CH2
CH3CH2
CHCH3
CH3
CH2CH2
CH3CH
CH2CH3
CH3
CH2CH3CH2
CCH3
CH3
CH3
CH2CH3C
CH2CH3
CH3
CH3
CHCH3CH2
CCH3
CH3
CH3
CH3
CHCH3CH2
CHCH3
CH3 CH3
CH2CH3CH
CH2CH3
CH2CH3
CH3CH
CCH3
CH3
CH3CH3
RON
0
52
42
83
81
93
65
91
112
Structure (C7H16)
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Chemical complexity of combustion
Marques et al., J. Braz. Chem. Soc., 2006, 17, 302-315
iBuOH+H=H2+C4H9Oi1 2.7e+07 1.76 7453.56 iBuOH+H=H2+C4H9Oi2 1.74e+07 1.48 3442.4 iBuOH+H=H2+C4H9Oi3 1.09e+07 1.59 3352.7 iBuOH+H=H2+C4H9Oi4 4.05e+04 2.38 9.34e+03 iBuOH+C2H3=C4H9Oi1+C2H4 1.10e-03 4.55 3505 iBuOH+C2H3=C4H9Oi2+C2H4 2.69e-02 3.9 684.9 iBuOH+C2H3=C4H9Oi3+C2H4 5.19e-02 3.9 861.37 iBuOH+CH3=CH4+C4H9Oi1 1.61e+00 3.59 7719.45 iBuOH+CH3=CH4+C4H9Oi2 4.14e+02 2.87 4899.5 iBuOH+CH3=CH4+C4H9Oi3 1.87e+00 3.50 6.00e+03 iBuOH+CH3=CH4+C4H9Oi4 2.32e+00 3.49 6.09e+03 iBuOH+CH2OH=C4H9Oi1+CH3OH 1.040E+06 1.800 15050.00 iBuOH+CH2OH=C4H9Oi2+CH3OH 0.99140E+06 1.753 12532.12 iBuOH+CH2OH=C4H9Oi3+CH3OH 0.99040E+06 1.786 13448.33 iBuOH+CH2OH=C4H9Oi4+CH3OH 0.250E-04 5.000 12580.00 iBuOH+OH=H2O+C4H9Oi3 3.61E+03 2.89 -2291 iBuOH+OH=H2O+C4H9Oi2 1.54 3.7 -4940 iBuOH+OH=H2O+C4H9Oi1 5.4E+06 2 5 12.64 iBuOH+OH=H2O+C4H9Oi4 5.88e2 2.82 -584.58 iBuOH+O2=C4H9Oi1+HO2 1.206E14 0.0 51.87e+03 iBuOH+O2=C4H9Oi2+HO2 1.588E14 0.0 47.69e+03 iBuOH+O2=C4H9Oi3+HO2 1.588E14 0.0 47.69e+03 iBuOH+O2=C4H9Oi4+HO2 2.325E12 0.0 74.12e+03 iBuOH+O=C4H9Oi1+OH 9.540E+04 2.710 2106.00 iBuOH+O=C4H9Oi2+OH 0.78E+05 2.5 1113.77 iBuOH+O=C4H9Oi3+OH 1.289E+05 2.79 2183.65 iBuOH+O=C4H9Oi4+OH 1.000E+13 0.000 4690.00 C4H9Oi3+O2=C4H8O-i3+HO2 5.28E+17 -1.638 8.39E+02 C4H9Oi1+O2=C4H8O-i1+HO2 7.23E+12 0.0 15998.4 O2+C4H9Oi3=HO2+C4H8O-i2 7.23E+12 0.0 15998.4 O2+C4H9Oi2=HO2+C4H8O-i1 7.23E+12 0.0 15998.4 O2+C4H9Oi2=HO2+C4H8O-i2 7.23E+12 0.0 15998.4 iBuOH+CH3O=C4H9Oi1+CH3OH 2.820E+11 0.000 7000.00 iBuOH+CH3O=C4H9Oi2+CH3OH 2.200E+11 0.000 4570.00 iBuOH+CH3O=C4H9Oi3+CH3OH 3.173E9 0.95 5644.0 C4H9Oi4+CH3OH=iBuOH+CH3O 2.820E+11 0.000 7000.00 C2H6+C4H9Oi1=iBuOH+C2H5 1.926e-05 5.28 7.78e+03 iBuOH+C2H5=C2H6+C4H9Oi2 1.41e-05 4.83 4.37e+03
Detailed chemistry of single fuel may have thousands of elementary reactions and
hundreds of species
38 different reactions
in initial step of iso-
butanol combustion
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Methane number – combustion chemistry?
The methane number (MN) is a parameter that is representative for the knocking
behavior of fuel gases.
https://www.youtube.com/watch?v=4ZysyokEU60
Auto-ignition of the fuel
Can be traced back to
the (auto-)ignition
chemistry of fuel gases
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Chemistry of ignition phenomenon
One of „the most important“ (ignition, explosions) reaction system is the H2/O2 system
Concentration of radicals is crucial for ignition
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Chemistry of ignition phenomenon
stationary reaction
slow reaction Explosion
chain terminating
(independent from T)
chain branching
(strongly T dependent)
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Low- to high-temperature ignition
RO2 QOOH
QOOHO2
R + O2
HO2 + alkene O-heterocycle + OH
ROOH
branching
H + alkene
branching oxygenated
products
RH
RH O2
H2O2
R’ + alkene
C-H
C-C
high temperature
(>1400 K)
low temperature
(400-700 K)
CH4, C2H6, C3H8, n-C4H10,
i-C4H10, n-C5H12, i-C5H12
n-C4H10, i-C4H10, n-C5H12,
i-C5H12
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Different experiments for different combustion
regimes
Goldsborough et al., Prog. Energy Combust. Sci., 2017, 63, 1-78
Different reactors and detection techniques can be used to probe the different chemistry happening in a combustion process
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Rapid Compression Machine (RCM)
Experiment to determine the ignition delay time
Reactor
chamber Pneumatic
driving
chamber
Hydraulic
braking
chamber
The reactor chamber is evacuated prior to the experiment and subsequently filled with fuel/O2/Ar/N2 mixture
Hydraulic chamber is pressurized prior to the experiment
The ball valve of the pneumatic system is opened to mobilise piston
The conical hydraulic piston is positioned in the
crevices (grooves) resulting in high pressure
braking and the hydraulic liquid is released
through a fast actuating magnetic valve
Compressed mixture is ignited and
pressure during the compression
and ignition is probed
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Typical pressure time trace in RCM
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Rapid Compression Machine at PTB
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Schematic design of the RCM at PTB
Reactor
Chamber
Hydraulic
Braking system Pneumatic Piston drive system
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Schematic design of the RCM at PTB
Technical data:
- Inner core: 50 mm
- 6 measuring ports for pressure gauges, thermocouples or
optical access
- Movable endwall
- Variable stroke: 150 – 250 mm
- Variable post compression volume
- Max. geometric compression ratio of V0/VEOC ≈ 21.6
- Max. working pressure: 1000 bar
- Design working pressure at EOC: 100 bar
- External resistive heating (up to 200° C)
The Reactor Chamber
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Schematic design of the RCM at PTB
Hydraulic Braking system:
Function:
- Piston speed control and braking
Technical data:
- Inner bore: 100 mm
- Variable length for stroke variation
- Max. working pressure: 500 bar
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Schematic design of the RCM at PTB
Pneumatic piston drive system
Function:
- Drives the piston
Technical data:
- Inner bore: 140 mm
- Max. working pressure: 50bar
- Pressure vessel of 100 l
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RCM – some facts
RCM
Range p = 1 – 100 bar, T = 500 – 1000 K
Measuring times 1 ms – 100 ms
Important influences
• Vorticity • Cooling-off of gases • Real gas behavior
Advantages • Long measuring times • Low experimental effort
Disadvantages • Possible pre-reactions due to long compression phase
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Results
Component CH4 C2H6 C3H8 n-C4H10 i-C4H10 n-C5H12 i-C5H12 N2 H2 𝜙=0.4 20bar
𝜙=0.4 40bar
𝜙=1.2 20bar
𝜙=1.2 40bar
calibration MN50 50 50
calibration MN60 60 40
calibration MN70 70 30
calibration MN80 80 20
calibration MN90 90 10
calibration MN100 100
Mix 1 78.8 14 3.4 0.9 1.1 0.15 0.15 1.5
Mix 2 Emirates 84.52 12.9 1.5 0.21 0.22 0.03 0.02 0.6
Mix 3 Norway 91.8 5.7 1.3 0.15 0.17 0.04 0.04 0.8
Mix 4 Libya 81.69 13.38 3.67 0.27 0.28 0.01 0.01 0.69
Mix 5 Oman 87.89 7.27 2.92 0.71 0.65 0.1 0.11 0.35
Mix 6 95.253 2 1 0.3 0.3 0.022 0.025 1.1
Mix 7 97.876 1 0.5 0.21 0.18 0.016 0.018 0.2
Mix 8 Alaska 99.68 0.09 0.03 0.01 0.01 0.005 0.005 0.17
Mix 8´ 99.54 0.1 0.1 0.08 0.08 0 0 0.1
Mix 9 99.4 0.3 0.3
Mix 10 99.6 0.2 0.2
Mix 11 99.8 0.1 0.1
Component CH4 C2H6 C3H8 n-C4H10 i-C4H10 n-C5H12 i-C5H12 N2 H2
calibration MN50 50 50
calibration MN60 60 40
calibration MN70 70 30
calibration MN80 80 20
calibration MN90 90 10
calibration MN100 100
Mix 1 78.8 14 3.4 0.9 1.1 0.15 0.15 1.5
Mix 2 Emirates 84.52 12.9 1.5 0.21 0.22 0.03 0.02 0.6
Mix 3 Norway 91.8 5.7 1.3 0.15 0.17 0.04 0.04 0.8
Mix 4 Libya 81.69 13.38 3.67 0.27 0.28 0.01 0.01 0.69
Mix 5 Oman 87.89 7.27 2.92 0.71 0.65 0.1 0.11 0.35
Mix 6 95.253 2 1 0.3 0.3 0.022 0.025 1.1
Mix 7 97.876 1 0.5 0.21 0.18 0.016 0.018 0.2
Mix 8 Alaska 99.68 0.09 0.03 0.01 0.01 0.005 0.005 0.17
Mix 8´ 99.54 0.1 0.1 0.08 0.08 0 0 0.1
Mix 9 99.4 0.3 0.3
Mix 10 99.6 0.2 0.2
Mix 11 99.8 0.1 0.1
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Task 3.3.1 – RCM ignition delay time measurements
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Overview
Component CH4 C2H6 C3H8 n-C4H10 i-C4H10 n-C5H12 i-C5H12 N2 H2 𝜙=0.4 20bar
𝜙=0.4 40bar
𝜙=1.2 20bar
𝜙=1.2 40bar
calibration MN50 50 50
calibration MN60 60 40 SIM. SIM.
calibration MN70 70 30 SIM. SIM.
calibration MN80 80 20 SIM. SIM.
calibration MN90 90 10 SIM. SIM.
calibration MN100 100 SIM. SIM.
calibration MN0 100 SIM. SIM.
Mix 1 78.8 14 3.4 0.9 1.1 0.15 0.15 1.5
Mix 2 Emirates 84.52 12.9 1.5 0.21 0.22 0.03 0.02 0.6
Mix 3 Norway 91.8 5.7 1.3 0.15 0.17 0.04 0.04 0.8
Mix 4 Libya 81.69 13.38 3.67 0.27 0.28 0.01 0.01 0.69
Mix 5 Oman 87.89 7.27 2.92 0.71 0.65 0.1 0.11 0.35
Mix 6 95.253 2 1 0.3 0.3 0.022 0.025 1.1
Mix 7 97.876 1 0.5 0.21 0.18 0.016 0.018 0.2
Mix 8 Alaska 99.68 0.09 0.03 0.01 0.01 0.005 0.005 0.17
Mix 8´ 99.54 0.1 0.1 0.08 0.08 0 0 0.1
Mix 9 99.4 0.3 0.3
Mix 10 99.6 0.2 0.2
Mix 11 99.8 0.1 0.1
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Reproducibility and Uncertainty
• Reproducibility of ignition delay time: ±5%
• Uncertainty of ignition delay time: ±20%
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Some exemplary results – Reference mixtures
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Some exemplary results – Reference mixtures
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Some exemplary results – LNG mixtures
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Some exemplary results – LNG mixtures
outlier?
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Some exemplary results – LNG mixtures
Component CH4 C2H6 C3H8 n-
C4H10 i-C4H10
n-C5H12
i-C5H12 N2 H2 AVL-MN
calibration MN50 50 50 50
calibration MN60 60 40 60
calibration MN70 70 30 70
calibration MN80 80 20 80
calibration MN90 90 10 90
calibration MN100
100 100
Mix 1 78.8 14 3.4 0.9 1.1 0.15 0.15 1.5 59
Mix 2 Emirates 84.52 12.9 1.5 0.21 0.22 0.03 0.02 0.6 69
Mix 3 Norway 91.8 5.7 1.3 0.15 0.17 0.04 0.04 0.8 77
Mix 4 Libya 81.69 13.38 3.67 0.27 0.28 0.01 0.01 0.69 65
Mix 5 Oman 87.89 7.27 2.92 0.71 0.65 0.1 0.11 0.35 66
Mix 6 95.253 2 1 0.3 0.3 0.022 0.025 1.1 84
Mix 7 97.876 1 0.5 0.21 0.18 0.016 0.018 0.2 90
Mix 8 Alaska 99.68 0.09 0.03 0.01 0.01 0.005 0.005 0.17
Mix 8´ 99.54 0.1 0.1 0.08 0.08 0 0 0.1
Mix 9 99.4 0.3 0.3
Mix 10 99.6 0.2 0.2
Mix 11 99.8 0.1 0.1
Not a clear scientific picture!
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Some exemplary results – LNG mixtures
0 20 40 60 80 100
0
20
40
60
80
100
120
140
160
Phi= 0.4, 40 bar References 882-947 K
Mixtures 882-947 K
References 921-959 K
Mixtures 921-959 K
References 964-979 K
Mixtures 964-979 K
IDT
(m
s)
AVL-MN
A clear scientific picture was
not achievable in LNG II
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Outlook into LNG III
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Need: A predictive kinetic model
Marques et al., J. Braz. Chem. Soc., 2006, 17, 302-315
iBuOH+H=H2+C4H9Oi1 2.7e+07 1.76 7453.56 iBuOH+H=H2+C4H9Oi2 1.74e+07 1.48 3442.4 iBuOH+H=H2+C4H9Oi3 1.09e+07 1.59 3352.7 iBuOH+H=H2+C4H9Oi4 4.05e+04 2.38 9.34e+03 iBuOH+C2H3=C4H9Oi1+C2H4 1.10e-03 4.55 3505 iBuOH+C2H3=C4H9Oi2+C2H4 2.69e-02 3.9 684.9 iBuOH+C2H3=C4H9Oi3+C2H4 5.19e-02 3.9 861.37 iBuOH+CH3=CH4+C4H9Oi1 1.61e+00 3.59 7719.45 iBuOH+CH3=CH4+C4H9Oi2 4.14e+02 2.87 4899.5 iBuOH+CH3=CH4+C4H9Oi3 1.87e+00 3.50 6.00e+03 iBuOH+CH3=CH4+C4H9Oi4 2.32e+00 3.49 6.09e+03 iBuOH+CH2OH=C4H9Oi1+CH3OH 1.040E+06 1.800 15050.00 iBuOH+CH2OH=C4H9Oi2+CH3OH 0.99140E+06 1.753 12532.12 iBuOH+CH2OH=C4H9Oi3+CH3OH 0.99040E+06 1.786 13448.33 iBuOH+CH2OH=C4H9Oi4+CH3OH 0.250E-04 5.000 12580.00 iBuOH+OH=H2O+C4H9Oi3 3.61E+03 2.89 -2291 iBuOH+OH=H2O+C4H9Oi2 1.54 3.7 -4940 iBuOH+OH=H2O+C4H9Oi1 5.4E+06 2 5 12.64 iBuOH+OH=H2O+C4H9Oi4 5.88e2 2.82 -584.58 iBuOH+O2=C4H9Oi1+HO2 1.206E14 0.0 51.87e+03 iBuOH+O2=C4H9Oi2+HO2 1.588E14 0.0 47.69e+03 iBuOH+O2=C4H9Oi3+HO2 1.588E14 0.0 47.69e+03 iBuOH+O2=C4H9Oi4+HO2 2.325E12 0.0 74.12e+03 iBuOH+O=C4H9Oi1+OH 9.540E+04 2.710 2106.00 iBuOH+O=C4H9Oi2+OH 0.78E+05 2.5 1113.77 iBuOH+O=C4H9Oi3+OH 1.289E+05 2.79 2183.65 iBuOH+O=C4H9Oi4+OH 1.000E+13 0.000 4690.00 C4H9Oi3+O2=C4H8O-i3+HO2 5.28E+17 -1.638 8.39E+02 C4H9Oi1+O2=C4H8O-i1+HO2 7.23E+12 0.0 15998.4 O2+C4H9Oi3=HO2+C4H8O-i2 7.23E+12 0.0 15998.4 O2+C4H9Oi2=HO2+C4H8O-i1 7.23E+12 0.0 15998.4 O2+C4H9Oi2=HO2+C4H8O-i2 7.23E+12 0.0 15998.4 iBuOH+CH3O=C4H9Oi1+CH3OH 2.820E+11 0.000 7000.00 iBuOH+CH3O=C4H9Oi2+CH3OH 2.200E+11 0.000 4570.00 iBuOH+CH3O=C4H9Oi3+CH3OH 3.173E9 0.95 5644.0 C4H9Oi4+CH3OH=iBuOH+CH3O 2.820E+11 0.000 7000.00 C2H6+C4H9Oi1=iBuOH+C2H5 1.926e-05 5.28 7.78e+03 iBuOH+C2H5=C2H6+C4H9Oi2 1.41e-05 4.83 4.37e+03
22.08.2017 32 Training Day LNG II, 22nd August 2017
Outlook into LNG III – The strategy
Validated detailed
kinetic model reduced
kinetic model
Comprehensive
MN algorithm
0D engine
simulation
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Outlook into LNG III
Physikalisch-Technische Bundesanstalt
Braunschweig and Berlin
Bundesallee 100
38116 Braunschweig
Dr. Kai Moshammer
Phone: 0531 592-3340
E-Mail: [email protected] www.ptb.de
Thank you !!!