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

22.08.2017 2 Training Day LNG II, 22nd August 2017

Outline


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


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

http://en.wikipedia.org/wiki/File:Nicolaus-August-Otto.jpg

http://en.wikipedia.org/wiki/File:Diesel_1883.jpg


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)


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


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


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


Chemistry of ignition phenomenon

stationary reaction

slow reaction Explosion

chain terminating

(independent from T)

chain branching

(strongly T dependent)


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


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


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


Typical pressure time trace in RCM


Rapid Compression Machine at PTB


Schematic design of the RCM at PTB

Reactor

Chamber

Hydraulic

Braking system Pneumatic Piston drive system



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



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



Pneumatic piston drive system

Function:

- Drives the piston

Technical data:

- Inner bore: 140 mm

- Max. working pressure: 50bar

- Pressure vessel of 100 l


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


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 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 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


Task 3.3.1 – RCM ignition delay time measurements


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 MN60 60 40 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


Reproducibility and Uncertainty

• Reproducibility of ignition delay time: ±5%

• Uncertainty of ignition delay time: ±20%


Some exemplary results – Reference mixtures


Some exemplary results – LNG mixtures



outlier?



Component CH4 C2H6 C3H8 n-

C4H10 i-C4H10

n-C5H12

i-C5H12 N2 H2 AVL-MN

calibration MN50 50 50 50





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!



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


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


Outlook into LNG III – The strategy

Validated detailed

kinetic model reduced

kinetic model

Comprehensive

MN algorithm

0D engine

simulation

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 !!!

http://www.ptb.de/

ignition delay time measurements of lng mixtures · experiment to determine the ignition delay time...

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