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Vehicular Fuel Consumption Simulation and Measurement Dr. Horizon GITANO-BRIGGS University Science Malaysia . Challenges of Field FC and Emissions . Page 2 of 32. Individual Vehicle Variation Environmental Factors (Temp, Rain…) Driver Factors (Aggressive, slow)

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slide1

Vehicular Fuel Consumption

Simulation and Measurement

Dr. Horizon GITANO-BRIGGS

University Science Malaysia

challenges of field fc and emissions
Challenges of Field FC and Emissions

Page 2 of 32

Individual Vehicle Variation

Environmental Factors (Temp, Rain…)

Driver Factors (Aggressive, slow)

Load Factors (Hills, passengers)

Traffic Factors (Jammed, or free flowing)

Variation from vehicle to vehicle (identical units)

Tuning, Wear, part-to-part variation

Model to Model variation

Geographic Location Variation

Hills, Loads, Traffic, …

vehicle fc modeling
Vehicle FC Modeling

Page 3 of 32

Speed-Load model is useful and fairly accurate –but-

  • No acceleration load prediction

(can be included, but based on what acceleration?)

  • No Hill prediction

(again can be included, but what is the topology?)

  • Gearing can be included, but depends on shift speeds
    • Shift speeds vary by ~2x depending on driver aggression (3000rpm up shift mellow, 6000 racing)

Vehicle tuning: still need some engine data

vehicle power modeling
Vehicle Power Modeling

Vehicle Models can be good predictors of power.

They are less accurate at fuel consumption prediction.

Page 4 of 32

individual vehicle fc variation
Individual vehicle FC Variation

Page 5 of 32

Vehicle Load con not directly predict FC

Relies on knowledge of engine operating point and efficiency

  • Efficiency varies widely based on individual vehicles operation point (speed vs. torque) even at same power
effect of rider stance load tire pressure individual vehicle power and fc
Effect of Rider Stance, Load, Tire Pressure Individual vehicle Power and FC

20% ↑ FC

2 x ↑ Power

Page 13 of 29

fc review
FC Review

Page 7 of 32

Power = Torque x Speed

FC = Power x BSFC

(Break Specific Fuel Consumption, gm/kWh)

Car on highway: 15Nm, 6000 rpm, BSFC = 600 gm/kWh

P = 15 x 6000 x 2π / 60 = 9.4kW

FC = 600 * 9.4 = 5640 gm/hour

FC = 5640gm / 720gm/liter = 7.8 liters/hour

100km/h => 7.8l/100km

=> 13km/liter

engine bsfc gm kwh
Engine BSFC (gm/kWh)

270

280

290

Engine Torque

300

350

400

800

Engine Speed

Page 8 of 32

Maximum Torque Curve (WOT)

constant power curves
Constant Power Curves

Engine Torque

Engine Speed

Page 9 of 32

Power:

1 2 3 4 6 8 kW

various gear ratios
Various Gear Ratios

290

4th

Engine Torque

300

3rd

350

2nd

Engine Speed

Page 10 of 32

For same power BSFC varies from 290 to 350 (ie. 20%)

engine technology
Engine Technology

Page 11 of 32

Not all technologies will have similar patterns of FC or emissions (ie. it is hard to generalize FC/Emissions results)

Different technologies give different variations of FC

  • Carbureted 2T loses ~35% of fuel unburned typically
  • At idle it may be >70% due to miss-firing
  • Direct Fuel Injection can run exceptionally lean ay idle - Stratified

Gasoline vs. LPG leakage

  • LPG: Based on 1 study ~60% of tanks/systems had significant leaks
  • Gasoline systems will have fewer leaks as more noticeable, but suffer from more “pilferage”
idle combustion pressure comparison
Idle Combustion Pressure Comparison

3 x misfires

3 x misfires

Late combustion

Direct Fuel Injection: More consistent

Page 12 of 32

Carbureted: fires 1 out of 4 cycles

fleet vehicle fc variation
Fleet Vehicle FC Variation

Page 13 of 32

Variation: Gearing, Tire Size, Replacement Parts, Wear

  • Vehicle tuning varies (7% are grossly mistuned)
  • Driver behavior variation: 2x variation in acceleration

One study found FC ok in city but bad in rural because gearing was the same, and engines were revving too high for rural highway speeds

Re-geared for highway speeds and FC greatly improved

  • Probably require>30 vehicle samples for any reasonable estimates
dyno vs road testing
Dyno vs Road Testing

Page 14 of 32

Obvious environmental factors: Temp, rain, road surface

  • 2ndary: Engine temps
  • Even with careful control may still have ~10% variation (road – dyno)
  • While dyno tests may not give exactly the same FC numbers as road tests, they are pretty good at vehicle to vehicle comparisons

Strive to get a dyno test to match the road FC, but don’t stress! The vehicle to vehicle comparison should still be valid unless the dyno test is totally inappropriate!

dynamometry measurements good for comparisons
Dynamometry Measurements: good for comparisons

Fuel economy of 4-stroke and 2-stoke motorcycles

Vehicle fuel economy as function of motorcycle age

Page 24 of 29

slide16

Dynamometry Measurements: good for comparisons

Fuel economy versus engine size

Fuel economy by manufacturer

Page 25 of 29

dynamometry studies
Dynamometry Studies

part throttle resulting in high pumping losses

extra work done to overcome the larger aerodynamic drag

Optimum speed for best FE

Some studies are much easier to do on a dynamometer

Page 15 of 29

dynamometry studies1
Dynamometry Studies

Optimum speed for best FE

Technology comparison: Carb vs EFI

Page 15 of 29

drive cycle comparison
Drive Cycle Comparison

ECER40

M’sian

Urban Cycle

M’sians accelerate more aggressively, faster and spend less time stopped

Page 19 of 32

drive cycle analysis malaysia
Drive Cycle Analysis: Malaysia

600 motorcycle survey

Average mileage 5500km/year

Similar speeds and accelerations

Page 20 of 32

fuel consumption comparison chassis dyno vs on road
FUEL CONSUMPTION COMPARISON: Chassis Dyno vs. On-Road

The vehicle was transient dyno tested on a representative drive cycle, and compared with on the road fuel consumption for that mode of driving. Typically there is a 10% difference between the 2 methods.

Page 21 of 29

fuel consumption and emissions factors
Fuel Consumption and Emissions Factors

Typical “balanced” drive cycle => 42.8 km/l

Annual mileage ~ 5,500km/year

128.5 l/vehicle per year

5,000,000 bbl/year total fuel consumption by motorcycles in Malaysia

Typical emissions (New carbureted small 4T motorcycles):

gm/km kg/vehicle/year kTons/year (Msia)

CO: 7.0 38 308

HC: 0.7 3.8 31

NOx: 0.15 0.83 6.6

CO2: 50 275 2200

Page 22 of 32

effect of technologies carb vs efi
Effect of Technologies: Carb vs EFI

Even if the test pattern doesn’t match the road cycle exactly, the differences between various technologies should be obvious:

Emissions (gm/km) on the ECE-R40 Test:

CarburetedEFI

CO: 7.0 1.1

HC: 0.7 0.24

NOx: 0.15 0.08

CO2: 50 55

Page 23 of 32

field fc measurements
Field FC Measurements

Page 24 of 32

Individual tank fill-ups variation is large (>10%)

  • Probably requires ~10 tank fills (Empty to Full 10x)
  • Data taking sometimes questionable (does the recorder care about data quality?)

Running with a calibrated fuel bottle will give accurate results for a given drive. This is SOP for Shell Eco Marathon and similar “eco races”.

field vehicle measurements
Field Vehicle Measurements

Page 25 of 32

GPS is ok for speed, but it may overestimates speed when slow (dither)

  • Wheel sped pick better: gives good V and A and distance
  • No hill, no load info

Simple, inexpensive data loggers can track a vehicles movement for months with high resolution.

data collection wheel speed pickup
Data Collection: Wheel Speed pickup

Target

Sensor

  • Data from the speed pickup is stored in the portable data logger at 10Hz and later downloaded into the computer.
  • RPM vs Time

Inductive sensor reads signal from 2 targets on rear wheel, 180 degrees apart

Page 26 of 32

motorcycle roll down test gps vs wheel speed
Motorcycle Roll Down Test: GPS vs Wheel Speed

Notice Model and Wheel Data overlay (good agreement)

Aerodynamic resistance

dominates

Rolling resistance

dominates

Page 9 of 29

instrumentation advanced concepts
Instrumentation: Advanced Concepts

Outer section is separate from inner section. Torque compresses springs, allowing outer section to rotate with respect to inner section. Features on both sections are detected by speed pickup.

Page 28 of 32

Torque sprocket: Measures both speed and torque at wheel

  • Includes hill and load effects (but not engine efficiency)
  • Torque Spkt + engine speed (from generator signal) can be decent predictor of engine operating condition (speed torque) and thus FC
instrumentation advanced concepts1
Instrumentation: Advanced Concepts

Page 29 of 32

Torque sprocket: Speed, Torque, and Acceleration (from V)

instrumentation advanced concepts2
Instrumentation: Advanced Concepts

Page 30 of 32

In fuel injected vehicles the ECU “knows” how much fuel is being injected. OBD 2 (On Board Diagnostics) Vehicles can have FC read directly from the ECU

On non-OBD EFI systems Injection Duration can

easily be measured and combined with injector

calibration to get a good FC number

Carbureted vehicles can be instrumented with EFI sensors:

  • Measure engine speed and throttle position
  • Can back-calculate FC accurately if you have “mapped” the engine
instrumentation advanced concepts3
Instrumentation: Advanced Concepts

Injector Signal

Flow Rate

Delivered Fuel

Injector Signal Duration

Page 31 of 32

In EFI systems the injector does not open or close instantly.

The injector calibration curve will give the fuel delivered based on an injection duration (signal) including both of these effects.

instrumentation advanced concepts4
Instrumentation: Advanced Concepts

Page 32 of 32

2-T LPG EFI used for fuel tracking in bi-fuel motorcycle.

In gasoline mode (carbureted) can record info for gasoline FC via separate calculation

implications for cdms
Implications for CDMs

Page 33 of 32

Vehicle Measurement are crucial:

Wheel speed pickup V and A, and distance are reliable

Measuring Torque and speed we can estimate FC well

Engine Measurement are getting better:

TPS + Engine Speed, and Temp

With a “calibrated” vehicle we can accurately get the FC

Higher Resolution data, but on a limited number of vehicles?

Road “gas bottle” test still most reliable:

Still will have some variation so need several runs.

~30 vehicles to get a good idea of the FC for a given senario.

conclusions
Conclusions

Page 34 of 32

We can (and should) use standard tests to compare the emissions/FC benefits of various technologies

These tests should be as close to the real operating conditions as possible although standard (ie. dyno) tests may not correlate perfectly with field tests

Field tests are a good idea (for final confirmation) but must be well controlled:

  • Fuel metering should be very carefully controlled
  • Environmental conditions, loads, speeds, … should all be controlled

In-Stitu Instrumentation for monitoring actual usage is probably the best way to go in the long run. This may require further development of instrumentation.

slide36

Contacting Us

For more information please contact us via:

University Science Malaysia

HorizonUSM@yahoo.com

Focus Applied Technologies

Lot 1174 Jalan Hutan Lipur

Kpg. Sg. Buaya

Nibong Tebal 14300

Penang, Malaysia

+ (6016) 484-6524 (Voice)

+(604) 594-1025 (Fax)

Horizon@FocusAppliedTechnologies.com

www.FocusAppliedTechnologies.com

motorcycle power demand
Motorcycle Power Demand

Coefficient of drag, Cd

Coefficient of rolling resistance, Crr

Page 4 of 29

frontal area

vehicle mass

rider and payload mass

tire pressure

parameters affecting fuel consumption
Parameters Affecting Fuel Consumption

Factors

Effects

Motorcycle Condition

Vehicle’s Emission

Driving pattern

Fuel Consumption

Road Condition

Operational Cost

Environmental Condition

Page 2 of 29

motorcycle driving patterns comparison
Motorcycle Driving Patterns Comparison

Malaysia

Aggressive acceleration/breaking

Predominantly as commuters also as delivery and even in construction

Very different “rules” from cars

Lots of Motorcycle-only infrastructure

West (US, Europe)

More steady cruising with mild accelerations

Mainly for leisure and occasionally for commuting

Follow same rules as cars

Page 39 of 32

gear ratio effect 50 effect on fc
Gear Ratio Effect: +/- 50% effect on FC

Typical Seasoned Motorcycle

Page 14 of 29