Fuel Economy and CO2:
The Next Round
Thomas Kenney
Presented at:
SAE Powertrain & Fluid Systems Conference, Tampa, FL
October 27, 2004
But, What is Fuel Economy?
Fill-Ups
BSFC
(
g
FE
/
k
W
P
-hr)
E
e
r
W
(mp
eek
F
l
e
g)
b
a
L D
y
r
o
r
t
ivin
a
l
u
g
R
g
CAFE
s
e
a
nge
R ycle
C
FE
E
G
E
FE
F
y
(km
a
)
w
h
/l)
igC
km
H
e
us
g
0
a
r
e
0
v
t
A
o
t
1
e
D
me
e
/
)
Fl
l(
r
m
ivi
/k
r
g
(
n
O2
C
C
g
F
?
SAE Powertrain & Fluid Systems Conference,
Tampa, FL October 27, 2004
2
Specific Fuel Consumption
1000
Specific Fuel Consumption (g/kW-hr)
900
800
BSFC
700
ISFC
600
500
400
300
200
100
0
0.0
2.0
4.0
6.0
BMEP (bar)
8.0
SAE Powertrain & Fluid Systems Conference,
Tampa, FL October 27, 2004
10.0
12.0
3
Regulatory Drive Cycles
0.25
FUDS
0.20
FHDS
NEDC
Vehicle Acceleration (g)
0.15
Japan 10-15 Mode
0.10
0.05
0.00
-0.05
-0.10
-0.15
-0.20
-0.25
0
10
20
30
40
50
60
70
80
Vehicle Speed (mph)
FUDS
FHDS
NEDC
Japan 10-15
Time
sec
1372
765
1180
660
Distance
miles
7.45
10.26
6.84
2.59
Max Accel
g
0.164
0.146
0.109
0.082
Max Speed
mph
56.7
59.9
74.6
43.5
Avg Speed
mph
19.5
48.2
20.9
14.1
SAE Powertrain & Fluid Systems Conference,
Tampa, FL October 27, 2004
4
Unadjusted FE and Efficiency
AT Vehicles: North American Fleet
55
Turbo Diesels
Today’s BIC SI Technology: 4v PFI, VCT and 5-6 spd AT
M-H Fuel Economy (miles/gallon)
50
Passenger Car BIC Energy
Efficiency Trend Line (55 ton-mpg)
45
40
Truck BIC Energy
Efficiency Trend Line (52 ton-mpg)
35
30
25
20
15
50th Percentile - 48.5 ton-mpg
10
2000
3000
4000
5000
ETW (lb)
6000
7000
8000
TC Diesel Energy Efficiency – 75 to 80 ton-mpg
Hybrid Energy Efficiency – 80 to 100 ton-mpg
SAE Powertrain & Fluid Systems Conference,
Tampa, FL October 27, 2004
5
Relationships (1)
M-H FE (mpg) = (0.55/FEFUDS + 0.45/FEFHDS)-1
LABEL FE = (0.55/(0.9*FEFUDS) +
0.45/(0.78*FEFHDS))-1
ηEnergy = FEMH (mpg) * ETW
Label FE is an adjustment that attempts to consider the
differences between regulatory cycle and customer
driving for conventional SI vehicles
SAE Powertrain & Fluid Systems Conference,
Tampa, FL October 27, 2004
6
Relationships (2)
FE (mpg) ~ ρf (LHV)f η / EDemanded
where:
η = f (Technology, Operating Conditions)
Edemanded = f (Vehicle, Operating Conditions)
GE-FE = FEf (ρg/ρf) (LHVg/LHVf)
Fuel Consumption ~ 1 / FE
CO2 ~ (mCO2/mf) / FE
SAE Powertrain & Fluid Systems Conference,
Tampa, FL October 27, 2004
7
FE and CO2
1000
CO2 ~ 1/FE
900
800
Gasoline Fueled Vehicles
Diesel Fueled Vehicles
M-H CO2 (g/mile)
700
CNG Fueled Vehicles
100% Increase in FE
600
Ethanol Fueled Vehicles
Methanol Fueled Vehicles
500
400
50% Reduction in CO2
300
200
100
0
0
10
20
30
40
50
60
70
80
90
Metro-Highway Fuel Economy (mpg)
SAE Powertrain & Fluid Systems Conference,
Tampa, FL October 27, 2004
8
GE-FE and CO2
1000
900
800
Gasoline Fueled Vehicles
Diesel Fueled Vehicles
M-H CO2 (g/mile)
700
CNG Fueled Vehicles
600
Ethanol Fueled Vehicles
500
Methanol Fueled Vehicles
400
300
200
100
0
0
10
20
30
40
50
60
70
80
90
100
Gasoline Equivalent M-H Fuel Economy (mpg)
SAE Powertrain & Fluid Systems Conference,
Tampa, FL October 27, 2004
9
Customer Driving
Higher rates of acceleration and deceleration (>0.2 G)
Higher vehicle speeds
Longer idling periods
Longer and shorter trips
Colder starts
Hotter and colder, more humid ambient conditions
Higher climate control loads (heater and AC)
Higher electrical (60 A vs 22A) and accessory loads
Consequently, technology benefits vary
depending on customer driving habits
SAE Powertrain & Fluid Systems Conference,
Tampa, FL October 27, 2004
10
What Does Customer Driving Mean?
Customers could be disappointed if regulatory driving
cycle FE benefits for new technologies are not realized in
their vehicles when they use them
Customer FE improvements can be obtained from
technologies that have little, or no, benefit on the
regulatory drive cycles, such as:
Low ε glazing
Cabin insulation
Efficient A/C
Lower electrical loads
SAE Powertrain & Fluid Systems Conference,
Tampa, FL October 27, 2004
11
Tailpipe Emissions Constraint
Cycle Average NOX Aftertreatment Efficiency: Gasoline Vehicles (1.0% NOxEI)
100
98
Emission compliance with lean SI
engine calibrations is becoming
more challenging
94
92
90
88
US Tier 2 Bin 5
86
US PZEV
84
Euro IV
Cycle Average NOX Aftertreatment Efficiency: Diesel Vehicles (0.3% NOxEI)
82
100
80
90
10
20
30
40
50
60
70
80
80
M-H Vehicle FE (mpg)
European diesel tailpipe NOx
emission standards are more
lenient than those in the US
NOx Aftertrreatment Efficiency
NOx Aftertreatment Efficiency
96
70
60
50
40
30
US Tier 2 Bin 5
20
US PZEV
Euro IV
10
0
10
20
30
40
50
60
70
80
M-H Vehicle FE (mpg)
SAE Powertrain & Fluid Systems Conference,
Tampa, FL October 27, 2004
12
How Do We Get FE?
Typical Energy Utilization in an Spark Ignition Engine AT Vehicle
Engine Thermal Losses
62
Engine Mechanical and
Pumping Losses
12
Driveline Losses
3
Engine
Fuel
Transmission
(gasoline, diesel
methanol, CNG)
Fuel - 100
Start with 100 "units“ of
gasoline fuel energy
`
Kinetic Energy
Braking Losses
8
Transmission Losses
9
Accessories
1
SAE Powertrain & Fluid Systems Conference,
Tampa, FL October 27, 2004
Rolling Resistance
3
Aerodynamic Losses
2
13
Factors Affecting Vehicle FE
•
•
•
•
Powertrain Attributes
and Operating Strategy
Vehicle Attributes
Weight
Aerodynamics
Rolling Resistance
Accessories
Overall
Powertrain η
Power and
Energy (Work)
Requirements
Operating Conditions
Drive Cycle
Emissions
Environment
f(E, η)
Vehicle Fuel Economy
SAE Powertrain & Fluid Systems Conference,
Tampa, FL October 27, 2004
14
Sensitivity of M-H Fuel Economy
to Vehicle Parameters (SUV)
1.00
Energy Conversion
and Transmission
0.90
0.80
M-H Sensitivity Factor
Vehicle Energy Sinks
0.70
0.60
0.50
0.40
0.30
0.20
0.10
0.00
Engine
Efficiency
Transmission
Efficiency
Accessory
Drive
Weight (no
rematch)
Weight
(w/rematch
considering
trailer tow)
Aero
SAE Powertrain & Fluid Systems Conference,
Tampa, FL October 27, 2004
Rolling
Resistance
Accessories
15
Strategies for Improving FE
Metro FE (mpg)
Combined/Total Vehicle "AND" Strategy
Increase Powertrain Efficiency
Reduce Energy Requirement
Lower Vehicle Energy
Base Vehicle Energy
Cycle Average Powertrain BSFC (g/kW-hr)
ROptimally:
Efficiency must increase and energy demand must decrease
SAE Powertrain & Fluid Systems Conference,
Tampa, FL October 27, 2004
16
Powertrain Attributes - Engine
Engine Attributes
Parasitic Losses
Mechanical Friction
• Rubbing Losses
• Accessories
Pumping Losses
• Throttling
Thermal Efficiency
• Compression Ratio
• Equivalence Ratio
• Load Factor
• Cylinder Displacement
• Dilution (EGR)
• Combustion Efficiency
• Combustion Stability
SAE Powertrain & Fluid Systems Conference,
Tampa, FL October 27, 2004
Dynamic Range
Speed
• 3 - Valve
• 4 - Valve
Boosting
• Turbocharging
• Supercharging
17
Effect of Engine Parameters on BSFC
25.0%
40.0
33.6
27.3
15.0%
15.0
13.5
10.0%
21.0
5
10
80%
15
20
85%
5.0%
90%
12.0
95% of Base
% Improvement in BSFC
20.0%
1997 4.6L V8 2V
WWMP
Base = 0% EGR,
53.4 kPa Mech FMEP,
9.0 CR,
14.6:1 A/F
10.5
0.0%
EGR (%)
Mech FMEP
Comp Ratio
SAE Powertrain & Fluid Systems Conference,
Tampa, FL October 27, 2004
A/F
18
1000
10
900
9
800
8
700
BSFC
7
600
FC Improvement for 0.1 bar Lower FMEP
6
500
5
400
4
300
3
200
2
100
1
0
0
12.0
0.0
2.0
4.0
6.0
BMEP (bar)
8.0
SAE Powertrain & Fluid Systems Conference,
Tampa, FL October 27, 2004
10.0
Fuel Consumption Improvement (%)
BSFC (g/kW-hr)
Effect of Friction Reduction
19
Elimination of Pumping Work
1.0
0.9
0.8
MEP (bar)
0.7
0.6
0.5
0.4
PMEP
0.3
Drive Cycle
0.2
0.1
0.0
0
200
400
600
800
1000
1200
1400
Time (seconds)
Eliminating all pumping work could increase M-H FE by 12%, if there are
no offsetting consequences; the practical potential is ~10%
SAE Powertrain & Fluid Systems Conference,
Tampa, FL October 27, 2004
20
DI-SC Example
Time Allocation on NEDC Drive Cycle
b
a
r
0
0
0
0
0
0
0
0
0
0
0
0
0
0
305
0
0
0
0
0
0
0
0
650
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
37
14
98
0
0
0
0
0
0
750
0
0
0
0
0
0
0
0
0
0
0
0
0
0
13
9
0
0
0
0
41
2
0
0
0
0
1000
0
0
0
0
0
0
0
0
0
0
0
0
5
10
13
13
0
0
0
0
0
0
5
0
0
0
0
1250
0
0
0
0
0
0
2
2
0
0
21
0
9
10
19
109
1
117
0
155
4
0
0
0
1
5
0
0
1500
0
0
0
0
0
0
0
0
0
0
14
10
8
4
24
0
0
0
0
0
0
0
0
0
0
0
0
2
0
1750
0
0
0
0
0
0
0
0
2
10
2
0
0
0
50
0
0
0
0
0
0
0
0
0
0
0
0
4
0
2000
0
0
0
0
0
0
0
0
7
5
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
2
0
2250
0
0
0
0
0
0
0
0
2
0
0
0
0
10
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
2500
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
4
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
2750
3000
3250
Engine Speed (rpm)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
3500
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
3750
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
4000
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
4500
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
5000
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
5500
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
6000
Stratified operation is
constrained to below
4.0 bar and 3000 rpm.
Outside of this region,
operation is at λ=1, and
the FE benefits are
significantly smaller.
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
6500
25
1000 rpm
1500 rpm
FE benefits strongly depend on
physical constraints, speed
and load; therefore the gains
are drive cycle dependent
20
BSFC Reduction (%)
B
M
E
P
12.0
11.5
11.0
10.5
10.0
9.5
9.0
8.5
8.0
7.5
7.0
6.5
6.0
5.5
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.2
1.0
0.5
0.0
-0.5
-1.0
-1.2
-1.5
-2.0
2000 rpm
2500 rpm
3000 rpm
15
10
5
0
0.0
1.0
SAE Powertrain & Fluid Systems Conference,
Tampa, FL October 27, 2004
2.0
3.0
BMEP (bar)
4.0
5.0
6.0
21
Dual Equal VCT
16
1200 RPM
14
1500 RPM
2000 RPM
BSFC Reduction (%)
12
2500 RPM
3000 RPM
10
8
6
4
2
0
0
10
20
30
40
50
60
Degrees of Dual Equal Cam Retard (CAD)
Maximum cam retard depends on engine load and speed; so that the
resulting FE benefit on the M-H cycle will be between 3% and 3.5%
over an EGR calibration, depending on the vehicle
SAE Powertrain & Fluid Systems Conference,
Tampa, FL October 27, 2004
22
Diesel Engines
Efficiency Improvements
Increased CR
Unthrottled Operation
Lean Calibration
Smaller Displacement
Offsets
Friction
Mixture Inhomogeneity
DPF Fueling Penalty
Lean NOx Fueling Penalty
∆FE ~ 35% to >50% M-H
∆GE-FE ~ 20% to >32%
∆FC ~ -26% to –34% M-H
∆CO2 ~ -17% to –25%
SAE Powertrain & Fluid Systems Conference,
Tampa, FL October 27, 2004
23
Powertrain Attributes - Transmission
Transmission Attributes
Parasitic Losses
Dynamic Range
• Gearbox Efficiency
• Torque Convertor Lock Schedule
• Fluid Viscosity
• Operating Temperature
• Clutch Design
• Hydraulic Pump Losses
SAE Powertrain & Fluid Systems Conference,
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• Ratio Span
• Ratio Steps
• Shift Scheduling
24
Powertrain Attributes - Hybridization
Hybridization
Increase Average Efficiency
• Engine Boost With Electric Motor
• Electric Drive Capability
• Engine Redesign for Fuel Efficiency
Reduce Losses
• Decel Fuel Shutoff
• Engine Off at Idle
• Regenerative Braking
SAE Powertrain & Fluid Systems Conference,
Tampa, FL October 27, 2004
25
Benefits of Hybridization
35%
% M-H Fuel Economy Gain
30%
Benefits estimated without penalty for added hardware
Each category benefit independent
13-31%
25%
20%
15%
6-11%
10%
4-6%
5%
2-4%
2-4%
0%
Decel Fuel
Shut-off
Idle Engine
Shut-off
Downsized
w/Electric
Assist
Regen to
Accessories
SAE Powertrain & Fluid Systems Conference,
Tampa, FL October 27, 2004
Regen to
Electric
Launch and
Accessories
26
Key Powertrain Technologies
Engine
Variable Cam Timing
Direct Injection
Variable Displacement
Friction Reduction
Boosting and Downsizing
HCCI
Diesel Engines
VNT
Piezo Fuel Injector
pHCCI
Transmission
6 Speed Automatic
CVT
Auto-Shift Manual
Strategy Refinement
Torque Converter Lockup
Decel Fuel Shutoff
Low Idle Speed
Energy Management
Hybridization
Observations
(Benefit of A) + (Benefit of B) < Benefit of A + Benefit of B
FE benefit for eliminating pumping work can only be claimed once
SAE Powertrain & Fluid Systems Conference,
Tampa, FL October 27, 2004
27
Crystal Ball: Automotive Industry
Today
2020
~17 M
~20M
Hybrid
0.3%
Up to 25%
Diesel
3%
Up to 15%
H2 ICE/FCV/FCEV
nil
Up to 5%
215 M
235 M to 245 M
Hybrid
<0.2%
Up to 15%
Diesel
3%
Up to 10%
H2 ICE/FCV/FCEV
nil
Up to 2%
Quality, Function,
Performance
Low Emissions, FE
Quality, Function,
Performance, ???
???
US Car & LDT Sales
US Car & LDT Fleet
Customers
Pay for
Do Not Pay for
SAE Powertrain & Fluid Systems Conference,
Tampa, FL October 27, 2004
28
Conclusions
Improving vehicle FE and reducing CO2 are clearly
becoming more important
There is no single technical prescription for improving
FE on all vehicles in all markets
Compliance with regulatory FE and CO2 standards
depends on the ability of new technologies to meet
customer expectations and satisfy customer needs.
All measures of FE/CO2 have to be explicitly considered
in developing vehicles to address these demands
SAE Powertrain & Fluid Systems Conference,
Tampa, FL October 27, 2004
29