Combustion Efficiency and Exhaust Emissions of …...1 4th Annual Conference on Ammonia, Oct 15 –...
Transcript of Combustion Efficiency and Exhaust Emissions of …...1 4th Annual Conference on Ammonia, Oct 15 –...
14th Annual Conference on Ammonia, Oct 15 – 16, 2007
Combustion Efficiency and Exhaust Emissions of Ammonia Combustion in
Diesel Engines
Song-Charng kong
Department of Mechanical Engineering
Iowa State University
Acknowledgements:Iowa Energy Center (Norman Olson, Tom Barton)
2Department of Mechanical Engineering, Iowa State University
Background
• Motivation
• Ammonia (NH3) combustion does not generate CO2
• Hydrogen carrier, renewable, etc.
• Challenges
• Ammonia is very difficult to ignite
• Octane number ~ 130
• Autoignition T ~ 651 ºC (gasoline: 440 ºC; diesel: 225 ºC)
• Ammonia flame temperature is lower than diesel flame T
• Erosive to some materials
• Ammonia emissions can be harmful
• Potential high NOx emissions due to fuel-bound nitrogen
3Department of Mechanical Engineering, Iowa State University
Approach
• Introduce ammonia to the intake manifold
• Create premixed ammonia/air mixture in the cylinder
• Inject diesel (or biodiesel) to initiate combustion
• Without modifying the existing diesel injection system
Diesel ignition
Induce NH3
combustion
Burn out
premixed NH3
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Ammonia Fueling System
• Fuel system
• Vapor ammonia introduced into the intake duct – after turbo,
before manifold
Liquid NH3 tank
Fuel lineInduction
point
Fuel line
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Review – Previous Results
• Demonstrated ammonia combustion with D2 and B100
2. Varied diesel and ammonia flow rates to maintain constant torque
0
50
100
150
200
250
300
0 20 40 60 80 100
1000 rpm
To
rqu
e (
ft-lb
)
Load (%)
Diesel+NH3
Diesel
1. Constant ammonia flow rate � constant torque increase
3. Used 5% diesel, varied ammonia flow rate for variable torque
0
50
100
150
200
250
0 20 40 60 80 100
1400 rpm, 5% Diesel Energy
To
rqu
e (
ft-lb
)
Load (%)
Diesel+NH3
Diesel
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Present Results
• Ammonia flow rate control
• Gaseous and particulate emissions
measurements
• Exhaust ammonia measurements
• Ammonia combustion efficiency
• Engine thermal efficiency analysis
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Ammonia Flow Rate Control
• Issues:
• Materials – require stainless steel, carbon steel
• High pressure, high flow rate (as compared to other lab uses)
• 0.5 lb/min for 1000 rpm, full load, 95% energy replacement
• Ag industrial application – regulating liquid ammonia at
higher flow rates
• Developed control mechanismFine tune
Coarse
adjustment
Safety
NH3
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Engine Test Results
• Obtained stable engine power output
Constant Peak Torque
Power vs. Load
0
5
10
15
20
25
30
35
40
45
0 20 40 60 80 100
Diesel Load %
Po
wer
(kW
)
Diesel Only
NH3 + Diesel
5% Diesel + NH3 Power vs. Load
0
5
10
15
20
25
30
35
40
45
0 20 40 60 80 100
Load %
Po
wer
(kW
)Diesel Only Full Curve
NH3 + Diesel
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CO2 Emissions
• Always much lower than diesel values
5% Diesel + NH3
CO2 (%Vol)
0
2
4
6
8
10
12
14
0 20 40 60 80 100
Load %
CO
2 (
%V
ol)
Diesel
Diesel + NH3
Constant Peak Torque
CO2 (%Vol)
0
2
4
6
8
10
12
14
0 20 40 60 80 100
Diesel Load %
CO
2 (
%V
ol)
Diesel 100% Load
NH3 + Diesel
Reduced CO2
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NO Emissions
• Ammonia can poison NO converter • Replace material from COM-03 to COM-GC3
• This “glassy carbon” is resistant to such poisoning
• Thermal NO & fuel-bound NO
5% Diesel + NH3
NO (ppm)
0
200
400
600
800
1000
1200
1400
1600
1800
0 20 40 60 80 100
Load %
NO
(p
pm
)
Diesel
Diesel + NH3
Constan Peak Torque
NO (ppm)
0
200
400
600
800
1000
1200
1400
1600
0 20 40 60 80 100
Diesel Load %
NO
(p
pm
)
Diesel 100% Load
NH3 + Diesel
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Hydrocarbon Emissions
• Hydrocarbons are higher
• Due possibly to incomplete combustion of diesel fuel caused
by lower flame temperature of ammonia
5% Diesel + NH3
HC (ppm)
0
50
100
150
200
250
300
0 20 40 60 80 100
Load %
HC
(pp
m)
Diesel
Diesel + NH3
Constan Peak Torque
HC (ppm)
0.0
100.0
200.0
300.0
400.0
500.0
600.0
700.0
0 20 40 60 80 100
Diesel Load %
HC
(pp
m)
Diesel 100% Load
NH3 + Diesel
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Soot Emissions
• Soot emissions vary depending on fueling rates
Constant Peak Torque
Soot
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
0 20 40 60 80 100
Diesel Load %
Filte
r S
mo
ke
Nu
mb
er
Diesel 100% Load
NH3 + Diesel
5% Diesel + NH3 Soot
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
0 20 40 60 80 100
Load %
Filte
r S
mo
ke
Nu
mb
er
Diesel 100% Load
NH3 + Diesel
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NH3 Exhaust Concentrations
• Concentrations vary depending on NH3 fueling rate
• Further study is required to reduce NH3 emissions.
Constan Peak Torque
NH3 in Exhaust (ppmV)
0
500
1000
1500
2000
2500
3000
3500
0.00 20.00 40.00 60.00 80.00 100.00
Diesel Load %
NH
3 (
pp
mV
)
5% Diesel + NH3
NH3 in Exhaust (ppmV)
0
2000
4000
6000
8000
10000
12000
14000
0 20 40 60 80 100
Load %
NH
3 p
pm
V
This strategy might not be feasible – not sufficient diesel energy to initiate combustion.
High
NH3
fueling Low NH3
fueling
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NH3 Intake/Exhaust Concentration
• Constant torque conditions
0
2
4
6
8
10
0 20 40 60 80 100
Constant Torque Conditions
NH
3 C
on
cen
tratio
n (
%)
Diesel Load (%)
Intake
Exhaust
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NH3 Combustion Efficiency
• Constant engine torque conditions
20
30
40
50
60
70
80
90
100
0 20 40 60 80 100
Constant Engine Torque
Vo
lum
etr
ic C
on
ve
rsio
n E
ffic
ien
cy (
%)
Diesel Load (%) 20
30
40
50
60
70
80
90
100
0 20 40 60 80 100
Constant Engine Torque
Ma
ss C
on
ve
rsio
n E
ffic
ien
cy (
%)
Diesel Load (%)
Volume conversion efficiencyMass conversion efficiency
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Summary
• Reasonable fuel economy between 40~60% diesel fueling
• Ammonia combustion efficiency ~ 95%
• Ammonia emissions: 1000 ~ 3000 ppm under the specific conditions tested
• Future work –
• Improve combustion efficiency of ammonia
• Ammonia flow rate control depending on engine loads
• Optimize diesel/ammonia dual-fuel system
• Ammonia removal in exhaust