The Low and Intermediate Temperature Oxidation of JP-8 and its Surrogate Components

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24 Οκτ 2013 (πριν από 4 χρόνια και 20 μέρες)

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The Low and Intermediate Temperature
Oxidation of JP
-
8 and its Surrogate Components

Julius Corrubia,
Farinaz

Farid
, Nicholas
Cernansky
, David Miller

Department of Mechanical Engineering and Mechanics, Drexel University, Philadelphia, PA 19104

1. BACKGROUND


The United States military is the largest consumer
of JP
-
8.


Department of Defense (
DoD
) proposed JP
-
8 as
the single fuel forward in all combustion systems.


A current interest exists in non
-
petroleum and
alternative source derived JP
-
8 to decrease
petroleum dependence.

-
Bio
-
derived

-
Natural gas (Fischer
-
Tropsch

process)

-
Coal (Hydro treating process)


The chemical composition of JP
-
8 is very complex.

-
Composition varies between different resources.

-
JP
-
8 consists of hundreds, if not thousands, of
hydrocarbon compounds spanning a wide range of
carbon numbers and chemical classes.


To reduce the chemical complexity of JP
-
8
surrogate fuels are developed to mimic
combustion properties of real fuels.

-
1
-
10 surrogate components comprise mixture.


While complete fundamental reaction kinetics of
real fuels are and will be beyond reach, those of
surrogates are tractable and they can be modeled
by detailed or semi
-
detailed reaction kinetic
models.

2. OBJECTIVES


To improve our ability to simulate fuel combustion
in air
-
breathing propulsion devices.


To accomplish the objectives three research tasks
have been identified:

(1)
Understand and quantify combustion
properties of real fuels.

(2)
Select appropriate surrogates.

(3)
Develop detailed reaction kinetic models and
strategies for model reduction.

3. EXPERIMENTAL FACILITIES


Pressurized Flow Reactor (PFR)


Gas Chromatograph / Mass
Spectrometer / Flame Ionization
Detector (GC / MS / FID)

4. EXPERIMENTAL METHODOLOGY

5. RESULTS AND DISCUSSION

7. SUMMARY AND FUTURE WORK

0
100
200
300
400
500
600
700
800
900
500
600
700
800
CO Molar Fraction (ppm)

Temperature (K)

Experiment 1
Experiment 2
0
50
100
150
200
250
300
350
500
600
700
800
CO
2

Molar Fraction (ppm)

Temperature (K)

Experiment 1
Experiment 2

Reactivity maps for n
-
Dodecane

oxidation in PFR


Discussion:

-
n
-
dodecane

was chosen to represent a surrogate
component of natural gas derived jet fuel.

-
Maximum reactivity occurs at the start of the
Negative Temperature Coefficient (NTC) regime.

-
NTC phenomena is defined as a decrease in
reactivity as temperature increases.

-
NTC behavior begins at 675 K with a CO molar
concentration of 770
ppm

and a CO
2

molar
concentration of approximately 250
ppm
.


n
-
dodecane

was oxidized in the PFR to investigate
its low to intermediate temperature reactivity.


Reactivity map results indicate that n
-
dodecane

exhibits NTC behavior.


Other surrogates for JP
-
8 to be examined.


Develop reliable kinetic models for surrogates.


Upgrades to PFR facility: Temperature, Mass Flow
and Pressure Controllers; TCD.



The PFR is designed to study the effects of
temperature and pressure on the oxidation of
hydrocarbon species with relative isolation from
fluid mechanics and temperature gradients.


PFR experiments are conducted using the
Direct Transfer Controlled Cool Down (DT
-
CCD)
methodology.

-
PFR is pre
-
heated to the maximum reaction
temperature of approximately 850 K.

-
Once PFR maximum reaction temperature is
stabilized the first sample is extracted and the
PFR is cooled at a rate of 2
-
5 K/min.

-
PFR Operating Conditions:








PFR samples are extracted from the PFR with
the sample probe and then injected into GC /
MS / FID for online analysis.

-
Identification and quantification of unknown
species from GC / MS / FID performed with
retention time matching, mass spectrum
matching and chromatogram analysis.








Temperature

Range

550


850 K

Pressure

8
atm

Equivalence Ratio

0.30

Residence Time

120 ms

N
2

Dilution in Fuel

80 %

-
Stable intermediate species are identified and
quantified with a Thermo
Finnigan

TraceDSQ

Mass
Spectrometer (MS) coupled to a Thermo
Finnigan

TraceGC

Gas Chromatograph (GC) and flame
ionization detector (FID).

6. RESULTS AND DISCUSSION


Fuel Consumption of n
-
Dodecane

(C
12
H
26
)

0
100
200
300
400
500
600
550
650
750
850
n
-
dodecane

Molar
Concentration (
ppm
)

Temperature (K)

Experiment 1
Experiment 2

Intermediate Species
-

Ethene

0
5
10
15
20
25
30
35
40
45
50
550
650
750
850
Ethene Molar
Concentration (ppm)

Temperature (K)

Experiment 1
Experiement 2

Discussion:

-
Minimum n
-
dodecane

concentration occurs at
approximately 675 K. This minimum parent fuel
concentration corresponds to the start of NTC.

-
Maximum
ethene

concentration of approximately
45
ppm

occurs at 750 K.

-
Other major intermediate species quantified
include: low molecular weight alkenes, low
molecular weight alkynes,
aldehydes
,
ketones

and
lactones.