2014 CRC Advanced Fuel and Engine Efficiency Workshop
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Effect of RON and Ethanol Concentration
on Engine Efficiency for HVs
Koichi Nakata
TOYOTA Motor Corporation
TOYOTA
Contents
2/24
1. Background & Engine Requirements for HV System
2. Engine Technologies for Enhancing Thermal Efficiency
3. Effect of High RON Fuels on Engine Thermal Efficiency
4. Desirable Ethanol Concentration for Driving Range
5. Conclusion
TOYOTA
Automotive Powertrain Issues
Global development
of industry &
technology
in the 21st century
Population growth
(in USA, Asia, etc.)
Growing number
of motor vehicles
Accelerated
consumption
of fossil fuels
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1. Energy issues
2. CO2 emission
(global warming measures)
3. Air quality
issues
Expansion of eco friendly vehicles is one of solutions
for environmental issues
TOYOTA
Advantage of Toyota Hybrid System
Engine
improvement
100
Index of CO2 (%)
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EV driving etc
Idle stop
Brake energy
recovery
Advantages of
hybrid vehicle
50
0
Conv.
Gasoline AT
Conv.
Diesel AT
Gasoline
Gasoline
Hybrid Vehicle
Future
PHV/EV
City Mode
Vehicle: Prius class
Estimated by TOYOTA
Hybrid system can reduce CO2 by approx. 50%
TOYOTA
CO2 Emission
[g/km] (EC mode)
CO2 emission of Toyota Hybrid Vehicles
300
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Gasoline
Turbo
Gasoline
Diesel
200
CAMRY
100
Toyota
Gasoline
HV
PRIUS
YARIS HV
0
1000
1500
2000
2500
Vehicle Weight [kg]
Hybrid system :Better CO2 than the other systems
TOYOTA
Hybrid Vehicle Sales
6/24
500
118
months
18 m. 14 m.
400
4 million units
350
3 million units
300
250
Cumulative
2 million units
200
100
80
150
60
100
40
1 million units
No. of units sold 20
50
0
1997
1999
2001
2003
2005
2007
2009
2011
Per year (ten thousand)
Cumulative (ten thousand)
450
27 m.
0
(Year) As of Aug.
2012
Hybrid Vehicle Sales plays an important role.
TOYOTA
Toyota Hybrid System (THS)
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• Classified in strong hybrid with high power battery
• Engine, motor, generator are connected by planetary gear
• Vehicle is propelled by engine and motor
• Battery power enables EV driving
Planetary
Gear
Generator
Engine
P.G.
Engine
direct Torque
Battery
Motor
Motor
Torque
Mechanical Path
Tire
Differential
Gear
Electric Path
TOYOTA
8/24
40
40
35
35
Prius (HV)
Corolla (CVT)
Corolla (MT)
30
25
30
25
20
20
15
15
10
10
5
5
0
0
50
0
EV
10
20
30
40
Distribution (%)
Brake Thermal Efficiency (%)
Features of THS
Engine Output (kW)
Key point : Engine Thermal Efficiency
TOYOTA
Contents
9/24
1. Background & Engine Requirements for HV System
2. Engine Technologies for Enhancing Thermal Efficiency
3. Effect of High RON Fuels on Engine Thermal Efficiency
4. Desirable Ethanol Concentration for Driving Range
5. Conclusion
TOYOTA
How to Enhance the Engine Thermal Efficiency
1) Theoretical Approach
ηth = 1 – 1/εκ-1
B
K
K : Knock
A
92RON
100RON
0.2
0.4
0.6
BMEP(MPa)
0.8
1
κ at 0OC
CO2 CH4 C2H6 C3H8
1.30 1.32 1.20 1.14
Lean Burn
Decrease in Cooling Heat Loss,
Mechanical Loss, and Pumping Loss
Heat Balance(%)
Thermal Efficiency(%)
2) Practical Approach
0
Air H20
1.40 1.33
κ=cp/cv
High Expansion Ratio
40
35
30
25
20
15
10
5
0
(Otto cycle)
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100
90
80
70
60
50
40
30
20
10
0
Unburned Loss
Cooling Heat Loss
Exhaust Heat Loss
Pumping Loss
Mechanical Loss
Break Thermal Efficiency
A
B
High Load and High RON Fuels
High Thermal Efficiency
High RON
Turbo Charger
Keyword : Atkinson cycle, Lean Boosted & High RON(Ethanol)
TOYOTA
Engine Thermal Efficiency
11/24
2800rpm Lambda=1
44
Lean Boosted
C.R=13 (Ethanol)
42
Thermal Efficiency(%)
40
38
Direct Injection
MPI
Lean Boosted
C.R=13 (100RON)
Lean Boosted
C.R=13 (92RON)
36
Atkinson cycle
C.R=13 (92RON)
34
32
30
Conventional
C.R=10 (92RON)
28
26
24
0.2
0.4
0.6
0.8
BMEP (MPa)
1
1.2
1.4
SAE 2007-01-2007
Keyword : Atkinson cycle, Lean Boosted & High RON(Ethanol)
TOYOTA
Contents
12/24
1. Background & Engine Requirements for HV System
2. Engine Technologies for Enhancing Thermal Efficiency
3. Effect of High RON Fuels on Engine Thermal Efficiency
4. Desirable Ethanol Concentration for Driving Range
5. Conclusion
TOYOTA
Test Engines
Engine
13/24
Engine1
Atkinson Cycle
Engine2
Lean Boosted
Spark Plug
4
Cylinder
4
Bore×Stroke
75mm×84.7mm
Displacement
1496cc
1796cc
Compression ratio
13
13
Port Fuel Injection
Port Fuel Injection
Fuel supply
Intake Valve
Exhaust Valve
80.5mm×88.2mm
Intake Valve Open
(deg BTDC)
-15～23
-35～20
Intake Valve Close
(deg ABDC)
105～67
105～50
Exhaust Valve Open
(deg BBDC)
34
51
Exhaust Valve Close
(deg ATDC)
2
3
International Journal of Engine Research 2011
TOYOTA
Test Fuels
14/24
Test Fuel Properties (Engine 1)
Net
Calorific
Value
(MJ/kg)
T90
(℃)
Ref.1
42.97
159.5
0
Ref.2
43.03
156.5
Ref.3
42.42
A
Bio
Density
Content (g/ml)
(%v/v)
RON
MON
0.733
90
81
90 RON gasoline
0
0.736
96.7
87
97 RON gasoline
148.5
0
0.76
100.2
87.1
100 RON gasoline
43.39
160.7
0
0.742
96
86.1
RF-02 (EN228) reference fuel
B
44.05
158.4
0
0.725
91.4
80.2
Highly paraffinic, low RON fuel
C
39.47
106
0.773
104.4
90.1
High RON fuel containing butanol-1 and ethanol
D1
41.62
108.8
0.763
105.9
92.2
Highly aromatic fuel containing ethanol
D2
41.21
106.7
10.4
0.762
107.1
93.9
Highly aromatic fuel containing ethanol
E
41.44
131.8
13.5
0.749
99
88.7
EN228 Gasoline with butanol-1
F
41.63
139.4
10.7
0.758
99.7
87
G
41.78
142.1
8.5
0.756
101.4
89.3
H
42.96
131.2
0
0.719
98.2
87
I
42.04
129.4
0
0.768
100.9
84.8
Racing gasoline(FIA Formula 1 specification)
E2
40.86
142.4
20
0.753
97.9
86.5
EN228 Gasoline with butanol-1
10.8
0
Description
EN228 Gasoline with ethanol and butanol-1
EN228 Gasoline with ethanol
Low aromatic fuel
Collaborative Program with BP
TOYOTA
Test Fuels
15/24
Test Fuel Properties (Engine 2)
Net
Calorifi
c
Value
(MJ/kg)
Boiling
Point
(oC)
Density
(g/ml)
RON
MON
Bio
Content
(vol%)
Ref.4
43.1
-
0.736
91.5
83
0
Ref.5
41.6
-
0.797
96.4
85.3
0
Ref.6
42.4
-
0.760
99.6
87.1
0
1-Butanol
33.33
118
0.810
98
84
100
isoButanol
33.21
108
0.801
105
91
100
Ethanol
26.57
78.3
0.794
109
90
100
TOYOTA
Thermal Efficiency (NA Engine)
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Brake Thermal
Efficiency (%)
42
With bio
1300rpm, WOT
2800rpm, WOT
40
5% increase
38
36
10% increase
34
32
Ignition Timing
(deg.BTDC)
25
MBT
20
15
10
MBT
5
0
90
95
100
RON
105
110
Collaborative Program with BP
TOYOTA
Thermal Efficiency (Lean Boosted)
Engine2, 2800rpm, λ1.6
45
Brake Thermal Efficiency (%)
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Ethanol
44
iso-butanol
43
42
Ref.6
(100RON)
41
40
1-butanol
39
38
0.2
0.4
0.6
0.8 1.0 1.2
BMEP (MPa)
1.4
1.6
TOYOTA
BMEP (MPa)
Brake Thermal
Efficiency(%)
Thermal Efficiency (Lean Boosted)
45
44
43
42
41
40
39
38
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
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Engine2, 2800rpm, λ1.6
Ref.6
Ethanol
iso-butanol
1-butanol
Ref.5
Ref.4
90
95
12.8%
7.4%
100
RON
105
110
TOYOTA
Effect of RON on Engine Thermal Efficiency
2800rpm
Improvement Rating (%)
14
12
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Lean Boosted Engine
10
8
NA Engine
6
4
2
0
90
95
100
105
110
RON
Effect ： (Lean Boosted) > (NA Engine)
TOYOTA
Contents
20/24
1. Background & Engine Requirements for HV System
2. Engine Technologies for Enhancing Thermal Efficiency
3. Effect of High RON Fuels on Engine Thermal Efficiency
4. Desirable Ethanol Concentration for Driving Range
5. Conclusion
TOYOTA
21/24
40
40
35
35
Prius (HV)
30
30
25
25
20
20
15
15
10
10
5
5
0
0
50
0
EV
10
20
30
40
Distribution (%)
Brake Thermal Efficiency (%)
Features of THS
Engine Output (kW)
Driving range depends on engine thermal efficiency.
TOYOTA
1.2
1.1
15
10
5
0
50
100
Ethanol Concentration (% )
Lean Boosted
Engine
0.9
0.7
1.2
0
1.0
0.8
22/24
20
High
Compression
Ratio Engine
Ethanol is considered as GHG=0%
1.0
T to W CO2
Volumetric Driving Range
Gasoline
Improvement of
the energy consumption (% )
Effect of Ethanol on Driving Range
0.8
0.6
0.4
0.2
Current Engine
0.6
0
50
100
Ethanol concentration (vol%)*
0.0
0
50
100
Ethanol concentration (vol%)*
*Base gasoline is 92RON
Customer could have a merit with Ethanol vol. < around 20%
TOYOTA
Conclusion
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1. Hybrid vehicles have large potential for reducing CO2.
2. Enhancing the maximum engine thermal efficiency
is essential for THS (Toyota Hybrid System).
3. The improving effect of lean boosted engine on
the thermal efficiency is larger than that of NA engine
with high RON fuels.
4. It is expected that the combination of future engine
technologies and around 20% ethanol fuels has
some merits for consumers.
TOYOTA
24/24
Thank you
for your kind attention
TOYOTA