Path to High Efficiency Gasoline Engine
SI
HCCI
PPC
Prof. Bengt Johansson
Division of Combustion Engines
Department of Energy Sciences
Lund University
1
Scania diesel engine running on gasoline
!
Group 3, 1300 [rpm]
60
Gross Indicated Efficiency [%]
55
50
FR47333CVX
FR47334CVX
FR47336CVX
45
40
35
30
25
20
0
2
ηi=57%
4
6
8
Gross IMEP [bar]
= Isfc =147 g/kWh
10
12
14
(@43 MJ/kg heating value)
2
Outline
• HCCI and fuel efficiency
– 50% thermal efficiency
• Partially premixed combustion, PPC
– Background
– Why gasoline is the best diesel engine fuel
– 56% thermal efficiency in car size engine
– 57% thermal efficiency in truck size engine
– Why 55% thermal efficiency is better than 57%
– How to reach 26 bar IMEP with US10
NOx, PM, HC and CO engine out
3
Outline
• HCCI and fuel efficiency
– 50% thermal efficiency
• Partially premixed combustion, PPC
– Background
– Why gasoline is the best diesel engine fuel
– 56% thermal efficiency in car size engine
– 57% thermal efficiency in truck size engine
– Why 55% thermal efficiency is better than 57%
– How to reach 26 bar IMEP with US10
NOx, PM, HC and CO engine out
4
Efficiencies?
5
Energy flow in an IC engine
FuelMEP
Combustion efficiency
QemisMEP
QhrMEP
Thermodynamic efficiency
QhtMEP
QlossMEP
QexhMEP
IMEPgross
Gross Indicated efficiency
Gas exchange efficiency
lMEPnet
Net Indicated efficiency
Mechanical efficiency
Brake efficiency
η
Brake
=η
PMEP
Combustion
FMEP
BMEP
*η
Thermodynamic
*η
GasExchange
*η
Mechanical
Thermodynamic efficiency
Saab SVC variable compression ratio, VCR, HCCI, Rc=10:1-30:1;
General Motors L850 “World engine”, HCCI, Rc=18:1, SI, Rc=18:1, SI, Rc=9.5:1 (std)
Scania D12 Heavy duty diesel engine, HCCI, Rc=18:1;
Fuel: US regular Gasoline
7
SAE2006-01-0205
All four efficiencies
8
Problem with HCCI: Too fast combustion
9
Phasing HCCI combustion late helps burn rate but
reduce ηC
Magnus Christensen Ph.D. thesis 2002
10
Outline
• HCCI and fuel efficiency
– 50% thermal efficiency
• Partially premixed combustion, PPC
– Background
– Why gasoline is the best diesel engine fuel
– 56% thermal efficiency in car size engine
– 57% thermal efficiency in truck size engine
– Why 55% thermal efficiency is better than 57%
– How to reach 26 bar IMEP with US10
NOx, PM, HC and CO engine out
11
+ Clean with 3-way
Catalyst
- Poor low & part load
efficiency
Background
Spark Ignition (SI)
engine (Gasoline,
Otto)
+ High efficiency
+ Ultra low NOx
Spark Assisted
Compression Ignition
(SACI)
Gasoline HCCI
Combustion concepts
+ High efficiency
- Emissions of NOx and
soot
Compression Ignition
(CI) engine (Diesel)
Homogeneous Charge
Compression Ignition
(HCCI)
-Combustion control
-Power density
Partially premixed
combustion (PPC)
Diesel HCCI
+ Injection controlled
- Less emissions
advantage
Partially Premixed Combustion, PPC
6000
y
PCCI
HCCI
5000
CI
1200
PPC
1000
4000
HC [ppm]
800
3000
600
2000
400
1000
200
-180
-160
-140
-100
-80
-120
SOI [ATDC]
-60
-40
NOx [ppm]
p
-20
Def: region between truly homogeneous combustion, HCCI,
and diffusion controlled combustion, diesel
13
PPC: Effect of EGR with diesel fuel
Load
8 bar IMEP
Abs. Inlet Pressure
2.5 bar
Engine Speed
1090 rpm
Swirl Ratio
1.7
Compression Ratio
12.4:1 (Low)
Scania D12 single cylinder
14
DEER2005
1
3
2
4
Lund/Delphi/Volvo PPC Project
Volvo D13 Multi-cylinder engine
NOx <0.3 g/kWh
PM < 2 FSN
using
Swedish MK1 diesel fuel
Adapted from
SAE paper 2009-01-1127
16
Outline
• HCCI and fuel efficiency
– 50% thermal efficiency
• Partially premixed combustion, PPC
– Background
– Why gasoline is the best diesel engine fuel
– 56% thermal efficiency in car size engine
– 57% thermal efficiency in truck size engine
– Why 55% thermal efficiency is better than 57%
– How to reach 26 bar IMEP with US10
NOx, PM, HC and CO engine out
17
PPC with low cetane diesel
Lic. Thesis by Henrik Nordgren 2005 and
presented at DEER2005
18
Outline
• HCCI and fuel efficiency
– 50% thermal efficiency
• Partially premixed combustion, PPC
– Background
– Why gasoline is the best diesel engine fuel
– 56% thermal efficiency in car size engine
– 57% thermal efficiency in truck size engine
– Why 55% thermal efficiency is better than 57%
– How to reach 26 bar IMEP with US10
NOx, PM, HC and CO engine out
19
VOLVO D5 with Gasoline
Injection
SOI [TDC]
Fuel MEP [bar]
Percentage [%]
1
-64.00
10.88
41.28
2
-29.20
7.74
29.36
3
0.80
7.74
29.36
150
Cyl Pressure [bar]
Inj Signal [a.u.]
RoHR [J/CAD]
100
N
2000
[rpm]
IMEPg
13.38
[bar]
Pin
2.57
[bar]
Tin
354
[K]
39
[%]
EGR
lambda
1.75
[-]
Noise
Load
Load & CA50
50
0
20
-80
-60
-40
-20
CAD [TDC]
0
20
40
Efficiencies & Emissions
!
60
D60 project goal
40
58
0.46 %
35
56
30
52
Emissions
Efficiency [%]
54
50
48
91 %
46
20
15
4598 ppm
13 ppm
10
44
Below
Detectable
Level
5
42
40
25
Indicated Gross
Thermal
0
NOx*100 [g/kWh] CO [g/kWh]
Combustion/2
dPmax
7.20
[bar/CAD]
CA5
3.40
[TDC]
ID
-1.00
[CAD]
CA50
11.35
[TDC]
CA90-10
13.00
[CAD]
21
HC [g/kWh]
Soot [FSN]
Burn rate and ηT
Optimum Thermodynamic efficiency
150
Low effective
expansion
ratio
Cyl Pressure [bar]
Inj Signal [a.u.]
RoHR [J/CAD]
High heat
losses
100
50
0
-80
-60
-40
-20
CAD [TDC]
Premixedness 22
0
20
40
Outline
• HCCI and fuel efficiency
– 50% thermal efficiency
• Partially premixed combustion, PPC
– Background
– Why gasoline is the best diesel engine fuel
– 56% thermal efficiency in car size engine
– 57% thermal efficiency in truck size engine
– Why 55% thermal efficiency is better than 57%
– How to reach 26 bar IMEP with US10
NOx, PM, HC and CO engine out
23
Experimental setup, Scania D12
Bosch Common Rail
Prailmax
1600
[bar]
Orifices
8
[-]
Orifice Diameter
0.18
[mm]
Umbrella Angle
120
[deg]
15
[bar]
1951
[cm3]
2.9
[-]
Engine / Dyno Spec
BMEPmax
Vd
Swirl ratio
Fuel: Gasoline or Ethanol
24
Two Test Series: High & Low Compression Ratio
rc: 14.3:1
rc: 17.1:1
High Compression Ratio PPC
Low Compression Ratio PPC
25
Injection Strategy
It consists of two injections. The first
one is placed @ -60 TDC to create a
homogeneous mixture while the second
around TDC. The stratification created
by the second injection triggers the
combustion. The first injection must not
react during the compression stroke,
this is achieved by using EGR.
Const.
1
[a.u.]
0.8
0.6
It must not
react during
compression
0.4
0.2
0
-60
-50
-40
Fuel amount in the pilot is a
function of:
1.rc
2.RON/MON
3.EGR
26
SAE 2009-01-0944
Load & CA50
-20
-30
CAD [TDC]
-10
0
10
High Compression Ratio PPC
IMEP sweep @ 1300 [rpm]
EGR ~ const throughout the sweep, 40-50 [%]
λ~ const throughout the sweep, 1.5-1.6 [-]
Tin = 308 [K]
Standard piston bowl, rc: 17:1
27
SAE 2009-01-2668
Running Conditions
Inlet Temperature
Exhaust Temperature
2
300
1.9
2
200
150
4
5
6
7
9
8
10
Gross IMEP [bar]
11
12
1.6
45
40
1.4
50
1.5
50
1.5
100
1.75
55
1.7
λ [-]
Inlet Pressure
Exhaust Pressure
60
1.8
250
[C]
[bar]
2.25
350
35
1.3
1.2
0
13
28
4
5
6
7
9
10
8
Gross IMEP [bar]
11
12
30
13
EGR [%]
2.5
Efficiencies
100
95
90
85
[%]
80
Combustion Efficiency
Thermal Efficiency
Gas Exchange Efficiency
Mechanical Efficiency
75
70
65
60
55
50
29
4
5
6
7
8
9
10
Gross IMEP [bar]
11
12
13
Efficiency
57%
Too much rate
controlled combustion
60
Too much heat transfer
55
[%]
50
45
Gross Ind. Efficiency
Net Ind. Efficiency
Brake Efficiency
40
35
30
2
4
6
8
10
Gross IMEP [bar]
30
12
14
Emissions
5
0.5
Gross
Net
Brake
EU VI
US 10
0.45
0.4
4
Smoke [FSN]
0.3
0.25
0.2
3
2.5
2
0.15
1.5
0.1
1
0.05
0.5
0
2
4
6
8
10
Gross IMEP [bar]
12
0
14
2
5
18
4.5
16
4
3
2.5
6
8
10
Gross IMEP [bar]
12
14
Gross
Net
Brake
EU VI
US 10
12
2
10
8
6
1.5
1
4
0.5
2
0
4
14
Gross
Net
Brake
EU VI
US 10
3.5
HC [g/kWh]
Not well tuned EGR-λ
combination
3.5
CO [g/kWh]
NOx [g/kWh]
0.35
Obsolete injection
system
4.5
2
4
6
8
10
Gross IMEP [bar]
12
14
31
0
2
4
6
8
10
Gross IMEP [bar]
12
14
Outline
• HCCI and fuel efficiency
– 50% thermal efficiency
• Partially premixed combustion, PPC
– Background
– Why gasoline is the best diesel engine fuel
– 56% thermal efficiency in car size engine
– 57% thermal efficiency in truck size engine
– Why 55% thermal efficiency is better than 57%
– How to reach 26 bar IMEP with US10
NOx, PM, HC and CO engine out
32
Low Compression Ratio PPC
IMEP sweep @ 1300 [rpm]
EGR ~ const throughout the sweep, 40-50 [%]
λ~ const throughout the sweep, 1.5-1.6 [-]
Tin = 308 [K]
Custom piston bowl, rc: 14.3:1
33
SAE 2010-01-0871
Efficiencies
100
95
90
85
[%]
80
Combustion Efficiency
Thermal Efficiency
Gas Exchange Efficiency
Mechanical Efficiency
75
70
65
60
55
50
4
34
6
8
10
12
Gross IMEP [bar]
14
16
18
Emissions
2
0.6
NOx [g/kWh]
0.4
1.6
1.4
Smoke [FSN]
0.5
Better tuned EGR-λ
combination
1.8
Gross
Net
Brake
EU VI
US 10
0.3
0.2
1.2
1
0.8
0.6
0.4
0.1
0.2
0
2
4
6
8
10
12
Gross IMEP [bar]
14
16
0
18
1.5
6
8
10
12
Gross IMEP [bar]
14
16
18
10
Gross
Net
Brake
EU VI
US 10
1.2
9
Gross
Net
Brake
EU VI
US 10
8
7
0.9
CO [g/kWh]
HC [g/kWh]
4
0.6
6
5
4
3
0.3
2
1
0
2
4
6
8
10
12
Gross IMEP [bar]
14
16
18
35
0
2
4
6
8
10
12
Gross IMEP [bar]
14
16
18
Emissions – different fuels
Ethanol
FR47330CVX
FR47331CVX
FR47333CVX
FR47334CVX
FR47335CVX
FR47336CVX
FR47338CVX
0.45
0.4
NOx [g/kWh]
0.35
0.3
2.5
Ethanol
FR47330CVX
FR47331CVX
FR47333CVX
FR47334CVX
FR47335CVX
FR47336CVX
FR47338CVX
2
Soot [FSN]
0.5
0.25
0.2
1.5
1
0.15
0.5
0.1
0.05
0
2
4
6
8
10
12
14
Gross IMEP [bar]
16
18
0
20
Ethanol
FR47330CVX
FR47331CVX
FR47333CVX
FR47334CVX
FR47335CVX
FR47336CVX
FR47338CVX
6
8
10
12
14
Gross IMEP [bar]
16
18
20
8
6
Ethanol
FR47330CVX
FR47331CVX
FR47333CVX
FR47334CVX
FR47335CVX
FR47336CVX
FR47338CVX
9
8
7
HC [g/kWh]
10
CO [g/kWh]
4
10
12
4
6
5
4
3
2
2
0
2
2
4
6
8
10
12
14
Gross IMEP [bar]
16
18
20
36
1
0
2
4
6
8
10
12
14
Gross IMEP [bar]
16
18
20
Outline
• HCCI and fuel efficiency
– 50% thermal efficiency
• Partially premixed combustion, PPC
– Background
– Why gasoline is the best diesel engine fuel
– 56% thermal efficiency in car size engine
– 57% thermal efficiency in truck size engine
– Why 55% thermal efficiency is better than 57%
– How to reach 26 bar IMEP with US10
NOx, PM, HC and CO engine out
37
Experimental Apparatus, Scania D13
XPI Common Rail
Orifices
8
[-]
Orifice Diameter
0.19
[mm]
Umbrella Angle
148
[deg]
25
[bar]
Vd
2124
[cm3]
Swirl ratio
2.095
[-]
Engine / Dyno Spec
BMEPmax
38
Standard piston bowl, rc: 17.3:1
Efficiency
50% brake efficiency seems viable!!!
60
55
50
[%]
45
η brake
η net
η gross
40
35
30
25
20
5
10
20
15
Gross IMEP [bar]
39
25
30
Efficiency
50% brake efficiency  maximization of all intermediate
efficiencies
Brake
=
η
Combustion
η
⋅
Thermodynamic
η
⋅
GasExchange
η
⋅
100
90
η combustion
η gas exchange
η thermal
η mechanical
80
[%]
η
70
60
50
40
5
10
15 40
20
Gross IMEP [bar]
25
30
Mechanical
RoHR, Cylinder Pressure & Injection Signal
IMEPg: 26 [bar]
250
200
150
100
IMEPg: 20 [bar]
lambda: 1.32 [-]
EGR: 47.98 [%]
CA50: 13.9 [TDC]
Abs Pin: 3.64 [bar]
Abs Pex: 4.01 [bar]
Tin: 293 [K]
COV: 0.56 [%]
eta comb: 99.89 [%]
NOx: 0.264 [g/kWh]
HC: 0.091 [g/kW]
CO: 0.31 [g/kW]
Tex: 673 [K]
250
RoHR/3 [J/CAD]
Cylinder Pressure [bar]
Injection Current [a.u.]
200
150
100
0
-40
-20
0
CAD [TDC]
20
40
60
250
200
RoHR/3 [J/CAD]
Cylinder Pressure [bar]
Injection Current [a.u.]
-40
-20
40
20
0
CAD [TDC]
60
150
100
Abs Pin: 1.07 [bar]
Abs Pex: 1.15 [bar]
Tin: 308 [K]
Tex: 521 [K]
lambda: 1.57 [-]
EGR: 42.66 [%]
CA50: 9.71 [TDC]
COV: 2.2 [%]
eta comb: 94.16 [%]
NOx: 0.108 [g/kWh]
HC: 2.7 [g/kW]
CO: 23 [g/kW]
Soot: 0.0033 [FSN]
RoHR/3 [J/CAD]
Cylinder Pressure [bar]
Injection Current [a.u.]
50
-40
-20
0
CAD [TDC]
20
40
60
100
COV: 0.58 [%]
eta comb: 99.82 [%]
NOx: 0.281 [g/kWh]
HC: 0.1 [g/kW]
CO: 0.63 [g/kW]
RoHR/3 [J/CAD]
Cylinder Pressure [bar]
Injection Current [a.u.]
Soot: 0.31 [FSN]
0
-60
IMEPg: 5 [bar]
Abs Pin: 1.76 [bar]
Abs Pex: 2.73 [bar]
Tin: 291 [K]
Tex: 612 [K]
lambda: 1.48 [-]
EGR: 46.41 [%]
CA50: 6.82 [TDC]
COV: 1.2 [%]
eta comb: 99.4 [%]
NOx: 0.317 [g/kWh]
HC: 0.22 [g/kW]
CO: 2.6 [g/kW]
Soot: 0.05 [FSN]
50
0
-60
RoHR/3 [J/CAD]
Cylinder Pressure [bar]
Injection Current [a.u.]
Abs Pin: 2.35 [bar]
Abs Pex: 2.88 [bar]
Tin: 292 [K]
Tex: 623 [K]
lambda: 1.36 [-]
EGR: 46.69 [%]
CA50: 7.6 [TDC]
50
IMEPg: 11 [bar]
250
200
150
Soot: 0.21 [FSN]
100
250
50
50
0
-60
COV: 0.7 [%]
eta comb: 99.89 [%]
NOx: 0.201 [g/kWh]
HC: 0.082 [g/kW]
CO: 0.31 [g/kW]
200
150
Soot: 0.26 [FSN]
IMEPg: 16 [bar]
Abs Pin: 3.21 [bar]
Abs Pex: 3.48 [bar]
Tin: 293 [K]
Tex: 606 [K]
lambda: 1.37 [-]
EGR: 53.22 [%]
CA50: 9.27 [TDC]
0
-60
-40
-20
0
CAD [TDC]
20
40
60
-60
-40
-20
0
CAD [TDC]
20
40
60
RoHR, Cylinder Pressure & Injection Signal
IMEPg: 5 [bar]
250
200
150
100
Abs Pin: 1.07 [bar]
Abs Pex: 1.15 [bar]
Tin: 308 [K]
Tex: 521 [K]
lambda: 1.57 [-]
EGR: 42.66 [%]
CA50: 9.71 [TDC]
COV: 2.2 [%]
eta comb: 94.16 [%]
NOx: 0.108 [g/kWh]
HC: 2.7 [g/kW]
CO: 23 [g/kW]
Soot: 0.0033 [FSN]
RoHR/3 [J/CAD]
Cylinder Pressure [bar]
Injection Current [a.u.]
50
0
-60
-40
-20
0
CAD [TDC]
20
40
60
RoHR, Cylinder Pressure & Injection Signal
IMEPg: 11 [bar]
250
200
150
100
Abs Pin: 1.76 [bar]
Abs Pex: 2.73 [bar]
Tin: 291 [K]
Tex: 612 [K]
lambda: 1.48 [-]
EGR: 46.41 [%]
CA50: 6.82 [TDC]
COV: 1.2 [%]
eta comb: 99.4 [%]
NOx: 0.317 [g/kWh]
HC: 0.22 [g/kW]
CO: 2.6 [g/kW]
Soot: 0.05 [FSN]
RoHR/3 [J/CAD]
Cylinder Pressure [bar]
Injection Current [a.u.]
50
0
-60
-40
-20
0
CAD [TDC]
20
40
60
RoHR, Cylinder Pressure & Injection Signal
IMEPg: 16 [bar]
250
200
150
100
Abs Pin: 2.35 [bar]
Abs Pex: 2.88 [bar]
Tin: 292 [K]
Tex: 623 [K]
lambda: 1.36 [-]
EGR: 46.69 [%]
CA50: 7.6 [TDC]
COV: 0.58 [%]
eta comb: 99.82 [%]
NOx: 0.281 [g/kWh]
HC: 0.1 [g/kW]
CO: 0.63 [g/kW]
Soot: 0.31 [FSN]
RoHR/3 [J/CAD]
Cylinder Pressure [bar]
Injection Current [a.u.]
50
0
-60
-40
-20
0
CAD [TDC]
20
40
60
RoHR, Cylinder Pressure & Injection Signal
IMEPg: 20 [bar]
250
200
150
100
Abs Pin: 3.21 [bar]
Abs Pex: 3.48 [bar]
Tin: 293 [K]
Tex: 606 [K]
lambda: 1.37 [-]
EGR: 53.22 [%]
CA50: 9.27 [TDC]
COV: 0.7 [%]
eta comb: 99.89 [%]
NOx: 0.201 [g/kWh]
HC: 0.082 [g/kW]
CO: 0.31 [g/kW]
Soot: 0.21 [FSN]
RoHR/3 [J/CAD]
Cylinder Pressure [bar]
Injection Current [a.u.]
50
0
-60
-40
-20
0
CAD [TDC]
20
40
60
RoHR, Cylinder Pressure & Injection Signal
IMEPg: 26 [bar]
250
200
150
100
Abs Pin: 3.64 [bar]
Abs Pex: 4.01 [bar]
Tin: 293 [K]
Tex: 673 [K]
lambda: 1.32 [-]
EGR: 47.98 [%]
CA50: 13.9 [TDC]
COV: 0.56 [%]
eta comb: 99.89 [%]
NOx: 0.264 [g/kWh]
HC: 0.091 [g/kW]
CO: 0.31 [g/kW]
Soot: 0.26 [FSN]
RoHR/3 [J/CAD]
Cylinder Pressure [bar]
Injection Current [a.u.]
50
0
-60
-40
-20
0
CAD [TDC]
20
40
60
5
10
9
4.5
HD Engine Treshold
8
4
7
3.5
COV of IMEP [%]
Relative Maximum Pressure Rise Rate [bar/CAD]
Combustion Noise & Stability
6
5
4
3
3
2.5
2
1.5
2
1
1
0.5
0
0
5
10
20
15
Gross IMEP [bar]
25
0
30
47
HD Engine Treshold
0
5
10
20
15
Gross IMEP [bar]
25
30
Emissions
0.6
0.5
0.5
0.4
0.35
0.4
Soot [FSN]
Brake NOx [g/kWh]
0.45
Brake NOx
US10
EU VI
0.3
0.2
0.3
0.25
0.2
0.15
0.1
0.1
0.05
0
0
5
10
15
20
Gross IMEP [bar]
25
0
30
2
10
15
20
Gross IMEP [bar]
25
30
25
1.8
Brake HC
US 10
EU VI
1.6
1.4
Brake CO
US 10
EU VI
20
Brake CO [g/kWh]
Brake HC [g/kWh]
5
1.2
1
0.8
0.6
0.4
15
10
5
0.2
0
0
5
10
15
20
Gross IMEP [bar]
25
30
48
0
0
5
10
15
20
Gross IMEP [bar]
25
30
Summary
49
Brake Efficiency
58
D12 High rc, G. 80/75
D12 Low rc, G. 69/66
D13 Standard, G. 69/66
56
Brake Efficiency [%]
54
52
50
48
46
44
42
40
38
36
0
5
10
15
20
Gross IMEP [bar]
25
30
Brake efficiency in the range of 48-50% seems to be viable between
12.5 and 26 bar gross IMEP.
50
D13 Running on Diesel & Gasoline
52
D13 Gasoline
D13 Diesel
50
Brake Efficiency [%]
48
46
44
42
40
38
36
34
5
10
15
20
Gross IMEP [bar]
25
30
D13 Diesel was calibrated by Scania and the calibration was
done to meet EU V legislation.
Average improvement of 16.6% points @ high load!!!
51
Brake Emissions
4.5
0.6
0.55
D12 High rc
D12 Low rc
D13 Standard
EU VI
US 10
0.45
0.4
3.5
3
Soot [FSN]
Brake Specific NOx [g/kWh]
0.5
0.35
0.3
0.25
0.15
0.5
0.05
0
5
10
15
20
Gross IMEP [bar]
25
0
30
0
5
10
20
15
Gross IMEP [bar]
25
30
35
4
D12 High rc
D12 Low rc
D13 Standard
EU VI
US 10
3
D12 High rc
D12 Low rc
D13 Standard
EU VI
US 10
30
Brake Specific CO [g/kWh]
3.5
Brake Specific HC [g/kWh]
2
1
0.1
2.5
2
1.5
1
25
20
15
10
5
0.5
0
2.5
1.5
0.2
0
D12 High rc
D12 Low rc
D13 Standard
4
0
5
10
15
20
Gross IMEP [bar]
25
30
52
0
0
5
10
15
20
Gross IMEP [bar]
25
30
Engine combustion - direction
+ Clean with 3-way
Catalyst
- Poor low & part load
efficiency
1900-1995
+ High efficiency
- Emissions of NOx
and soot
Compression
Ignition (CI) engine
(Diesel)
Spark Ignition (SI)
engine (Gasoline,
Otto)
Homogeneous
Charge
Compression
Ignition (HCCI)
1995-2005
+ Ultralow NOx & soot
- Combustion control
- Power density
2005-2010
Diesel PPC
+ High Efficiency
+ Low NOx & soot
2010-
+ High Efficiency
Gasoline PPC
53
+ Injection controlled
- Efficiency at high load
The End
Thank you
54
Path to High Efficiency Gasoline Engine
SI
HCCI
PPC
Prof. Bengt Johansson
Division of Combustion Engines
Department of Energy Sciences
Lund University
55
Outline
• Partially premixed combustion, PPC
– Summary of
• 56% thermal efficiency in car size engine
• 57% thermal efficiency in truck size engine
• Why 55% thermal efficiency is better than 57%
– Fuel effects in Scania D12 engine
– How to reach 26 bar IMEP with US10
NOx, PM, HC and CO engine out, Scania D13
– Fuel effects in Scania D13 engine
56
Fuel Matrix
Group 1
Group 2
Group 3
Group 4
RON
MON
C
H/C
O/C
LHV [MJ/kg]
A/F stoich
FR47335CVX
99.0
96.9
7.04
2.28
0.00
44.30
15.10
FR47332CVX
97.7
87.5
6.61
2.06
0.07
39.70
13.44
FR47337CVX
96.5
86.1
7.53
1.53
0.00
42.10
14.03
FR47338CVX
88.6
79.5
7.21
1.88
0.00
43.50
14.53
FR47330CVX
87.1
80.5
7.20
1.92
0.00
43.50
14.60
FR47331CVX
92.9
84.7
6.90
1.99
0.03
41.60
14.02
FR47336CVX
70.3
65.9
7.10
2.08
0.00
43.80
14.83
FR47334CVX
69.4
66.1
7.11
1.98
0.00
43.80
14.68
FR47333CVX
80.0
75.0
7.16
1.97
0.00
43.70
14.65
PRF20
20
20
7.2
2.28
0
44.51
15.07
MK1
n.a.
20
16
1.87
0
43.15
14.9
57
Results
58
Tested Load Area
Stable operational load vs. fuel type
25
IMEP gross [bar]
20
15
10
5
0
20
30
40
50
60
RON [-]
59
70
80
90
100
NOx - ηcomb Trade – Off Solution
100
Combustion Efficiency [%]
F/A EQUIVALENCE RATIO
99
98
G. ON 99/97
G. ON 98/88
G. ON 97/86
G. ON 93/85
G. ON 89/80
G. ON 87/81
G. ON 80/75
G. ON 70/66
G. ON 69/66
PRF20
97
96
95
94
93
92
91
HC/CO
90
TEMPERATURE
0
0.2
0.4
0.6
NOx [g/kWh]
Adiabatic Flame Temperature
2400
λ =1
λ =1.1
λ =1.2
λ =1.3
λ =1.4
λ =1.5
λ =1.6
λ =1.7
λ =1.8
λ =2
λ =2.5
λ =3
λ =3.5
λ =4
2200
Temperature [K]
2000
It is possible to achieve
low NOx and still keep
high combustion
efficiency in the whole
load range!
1800
1600
1400
1200
1000
30
0.8
60
35
40
45
50
EGR Ratio [%]
55
60
65
70
1
Efficiency & Emissions
60
58
57
56
55
54
0.045
0.035
0.03
0.025
0.02
0.015
53
0.01
52
0.005
51
50
G. ON 99/97
G. ON 98/88
G. ON 97/86
G. ON 93/85
G. ON 89/80
G. ON 87/81
G. ON 80/75
G. ON 70/66
G. ON 69/66
D. CN 52
PRF20
EU VI
US10
0.04
Soot [g/kWh]
59
Gross Indicated Efficiency [%]
0.05
G. ON 99/97
G. ON 98/88
G. ON 97/86
G. ON 93/85
G. ON 89/80
G. ON 87/81
G. ON 80/75
G. ON 70/66
G. ON 69/66
PRF20
0
0
0.2
0.4
0.6
NOx [g/kWh]
0.8
1
0
0.1
0.2
0.3 0.4 0.5 0.6 0.7
Indicated NOx [g/kWh]
In certain operating range, some fuels are capable to
comply EU VI & US10 legislations and still keep high
efficiency without compromising the efficiency!
61
0.8
0.9
1
Soot Emissions
3
G. ON 99/97
G. ON 98/88
G. ON 97/86
G. ON 93/85
G. ON 89/80
G. ON 87/81
G. ON 80/75
G. ON 70/66
G. ON 69/66
D. CN 52
PRF20
2.5
Soot [FSN]
2
1.5
1
Diesel vs. Gasoline
0.5
0
0
5
10
15
20
Gross IMEP [bar]
62
25
30
Higher Power Density
IMEPg: 20 & 25 [bar]
3
2.5
G. ON 99/97
G. ON 98/88
G. ON 97/86
G. ON 93/85
G. ON 89/80
G. ON 87/81
G. ON 80/75
G. ON 70/66
G. ON 69/66
D. CN 52
PRF20
Soot [FSN]
2
1.5
1
0.5
0
1
1.1
1.2
λ [-]
1.3
1.4
Low soot even @ λ 1.3  higher power
density without producing smoke!
63
1.5
Acoustic Noise
G. ON 99/97
G. ON 98/88
G. ON 97/86
G. ON 93/85
G. ON 89/80
G. ON 87/81
G. ON 80/75
G. ON 70/66
G. ON 69/66
D. CN 52
PRF20
Treshold
13
11
9
7
5
3
1
0
5
10
15
20
Gross IMEP [bar]
25
30
Motored Engine
5
Max Pressure Rise Rate [bar/CAD]
Relative Max Pressure Rise Rate [bar/CAD]
15
64
Measured
Normalized
4.5
4
3.5
3
2.5
2
1.5
1
1
1.5
2
2.5
3
abs Inlet Pressure [bar]
3.5
4
Idle
65
Efficiencies & Emissions
Gross Indicated Efficiency [%]
Thermal Efficiency [%]
48
46
99
42
96
40
95
38
94
36
93
34
92
32
91
0.05
90
10
0
30
3
4
5
6
7
8
Combustion Phasing [TDC]
9
NOx / Soot [g/kWh]
97
45
40
CO
HC
0.3
44
50
NOx
Soot
0.35
98
Combustion Efficiency
G. ON 69/66
0.4
[%]
[%]
100
35
0.25
30
0.2
25
0.15
20
15
0.1
66
10
5
3
4
5
6
7
8
Combustion Phasing [TDC]
9
0
10
CO / HC [g/kWh]
G. ON 69/66
50
Viability of Low ON Gasolines for
PPC?
67
Oil Refineries Production Layout
50%
50 < ON < 75
90 < ON < 99
20%
Octane Number of the gasoline streams span from 99 to 50 RON
68
 Gasolines with 70 RON are already produced!!!
30%
Oil Refineries Perspectives
Oil refineries are a very stiff system and their kerosene, diesel
and gasoline production can not be easily varied without major
investments  we need to build highly efficient vehicles with the
69
available fuels…
High ON Gasolines in Scania D13
What to do with these
fuels?!
25
Still to be used in SI
engines?!
IMEP gross [bar]
20
15
10
5
0
20
30
40
50
60
RON [-]
70
80
7070
Page
90
100
Minimum Turbo Efficiency
71
Ideal burn rate?
Conditions:
1. CA50: 8 [ATDC].
2. CA90-10: 15 [CAD].
3. Engine geometry: custom Scania D13.
4. Inlet temperature: 303 [K].
5. Reference temperature: 298 [K].
6. Engine speed: 1250 [rpm].
7. Differential pressure exhaust minus inlet: 0.25 [bar].
8. Cylinder wall temperature: 450 [K].
9. Heat transferred modeled with the Woschni equation and tuned to match the experimental results
10. The rate of heat release has been approximated with a Wiebe function.
11. EGR is added in order to have 1.35 as λ. If the inlet pressure was not enough to
have λ without EGR higher than 1.35, EGR was set to zero.
12. The combustion efficiency was assumed to be 100%.
13. Lower heating value 43.8 MJ/kg, stoichiometric air fuel ratio 14.68.
72
Exhaust Loss
73
Heat transfer loss
74
The rest (useful work)
75
Boosting reduce heat losses
76
A-B-C of Fuel Consumption
A. Car size
B. Engine size
C. Engine efficiency in right operating conditions
77
Porsche 911 performance with 100+ mpg?
• Two persons
• 100 liter of storage capacity
78
Porsche 911 data
M=1550 kg
Cr=0.012
Av=1.96 m2
Cd=0.33
Vd=3.8 liter
P=355 PS (hp)
T=400 Nm
Performance
0-60: 4.6 s
V,max=300 km/h ( 186.5 mph)
Fuel consump.= 12.0 l/100 km (19.6 mpg)
79
Power needed @300 km/h (186.5 mph)
(
)
P = C R mg + 0.5 ρ a C D Av v 2 v =
2

  300 
300


 0.012 x1550 x9.81 + 0.5 x1.2 x0.33 x1.96 x
 x




 3.6    3.6 

= 239.8kW = 326.1hp
80
The ”Cigar”
Two person capacity is often enough
UK National Office of Statistics:
“The average car occupancy is 1.6 people
per car and for commuting it's 1.2 “
A carpool in California
is a car with ONE
person if the car is fuel
efficient…
82
The ”Cigar”
Existing large model use
large BMW 1200 cc MC
engine. With turbo a top
speed of 315 km/h and fuel
consumption of 3.5 l/100 km
(67 mpg)
http://www.peraves.ch/
Power needed @300 km/h (186.5 mph)
Cigar design specifications
Cd=0.1
Av=0.5-1 m2
m= 250 kg
Cr=0.012 (two wheels)
(
)
P = C R mg + 0.5 ρ a C D Av v 2 v =
2

  300 
300


 0.012 x 250 x9.81 + 0.5 x1.2 x0.10 x1.0 x
 x




 3.6    3.6 

= 37.2kW = 49.7 hp
84
Power needed at 50 and 100 km/h (31- 62 mph)
Porsche 911 vs. cigar
Speed (km/h)
50
100
300
911
3.57
13.4
239.8
Cigar
0.57
2.1
37.2
Unit
kW
kW
kW
Ratio
6.28
6.36
6.45
50
100
300
4.86
18.2
326.1
0.77
2.9
49.7
hp
hp
hp
6.28
6.36
6.45
Acceleration proportional to power/mass ratio:
Cigar: 250/49.7=5.03 kg/hp
911: 1550/355=4.37 kg/hp
85
A. Car size
• With more correct car size the engine size can
be reduced a factor of 6 i.e. single cylinder
version of 911 engine with 633 cc
displacement is enough
• Porsche 911 has a fuel consumption of
12 l/100 km (19.6 mpg)
• Cigar would have
12/6=2 l/100 km (117.6 mpg)
without any need of new engine technology.
(Scaling both engine and car size)
86
B. Engine size
• A Porsche 911 does not operate at optimum
load points in normal driving.
• At 50 km/h the estimated load is only 2 bar
BMEP or less
• Bsfc=400 g/kWh
(ηb=21 %)
0
20
8740
60
80
100
120
140
160
180
200
220
Bilhast. [km/h]
Engine downsizing
Three options
1. Turbo or supercharge a small engine
2. Cylinder deactivation of large engine
3. Variable displacement i.e. variable engine size
88
B.1. Mercedes CDI 250, 2.1 liter
Vd=2143 cc
Torque= 500 Nm (369 lb-ft)
89
Two stage turbo
90
Engine downsizing- MB 250 CDI
Displacement of 2.1 liter giving 224 hp and 500 Nm of torque :
30 bar BMEP is now full load NOT 10 or 20 bar
Fuel consumption;
C-class 5.1 l/100 km (46.1 mpg),
E-class 5.3 l/100 km (44.4 mpg),
S-class 5.9 l/100 km (39.9 mpg)
CO2:
C-class 139 g/km
E-class 143 g/km
S-class 155 g/km
91
B2: Dual engine concept
• Use one small and one large engine
• As an example:
– One 2 cylinder 1 liter engine
– One 4 cylinder 2 liter engine
• This gives us 1, 2 or 3 liter to choose from
92
Layout 4 +2 cyl
Fiat 2-cylinder
production engine
FAS
Transm.
93
Operation
• 2-cyl at low loads
• 4-cyl operation at higher load operation
(Autobahn)
• 6-cyl operation at highest loads
• 6-cyl + FAS at transients
(with FAS start of 4-cyl)
• FAS for regenerative braking
• FAS for lowest speed operation ( < 5 km/h)
• Manual selection should be possible
94
B3: Variable displacement engine
• If we can change displacement, Vd, engine
load, P, can be controlled without reducing
BMEP!
N
P = bmep Vd
nt
95
Atkinson Cycle
Displacement from 0.15 to 0.85 l per cylinder
gives 0.6 to 3.4 l four cylinder engine at full load
(@max BMEP)
96
Atkinson engine with variable displacement
97
Atkinson engine efficiency
98
Atkinson engine thermal efficiency
99
A-B-C of Fuel Consumption
A. Car size
B. Engine size
C. Engine efficiency in right operating conditions
(Maximum engine efficiency)
100
Summary /ABC of fuel consumption
A. Correct car size gives factor of 6 in fuel consumption
B. Correct load point gives factor 2 in fuel consumption
(21%-42% or 400-200 g/kWh)
C. Partially Premixed Combustion have the potential to
extend brake efficiency to 50% with US10/Euro
emissions. With further optimization 55% could be
reached
D. With waste heat recovery 60% should be possible
giving a factor of 3 from today.
A total reduction potential of factor 18!
101
Cars and traffic situation
102