STUDY OF TRANSIT BUS DUTY CYCLE AND ITS INFLUENCE ON FUEL ECONOMY AND EMISSIONS OF DIESEL ELECTRIC-HYBRIDS Jairo A Sandoval Ph.D. Dissertation Proposal Center for Alternative Fuels, Engines and Emissions Mechanical and Aerospace Engineering West Virginia University March 5 th , 2010
Study of Transit Bus Duty Cycle and Its Influence on Fuel Economy and Emissions of Diesel Electric-Hybrids
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STUDY OF TRANSIT BUS DUTY CYCLE AND ITS INFLUENCE ON
FUEL ECONOMY AND EMISSIONS OF DIESEL ELECTRIC-HYBRIDS
Jairo A SandovalPh.D. Dissertation Proposal
Center for Alternative Fuels, Engines and EmissionsMechanical and Aerospace Engineering
West Virginia UniversityMarch 5th, 2010
Outline1. Motivation2. IBIS3. Objectives4. Methodology and Preliminary Results5. Contribution6. Timeline
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1. MotivationEnvironmental effects of transportationVehicle duty cycle Fuel economy &
Emissions Hybrid buses will not perform the same on all
service routesEmissions and fuel economy correlate very
well with cycle metrics, but transit agencies do not know the metrics corresponding to their operation (e.g. acceleration or % idle)
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Drive Cycle MetricsMetric Units
Percentage of Idle %
Stops per mile mi-1
Maximum Speed,
Acceleration (+/-),
Grade (+/-)
-
Average Speed mph
Average Speed w/o idle mph
Aerodynamic Speed mph
Standard Deviation of
Speedmph
Standard Deviation of
Speed w/o Idlemph
Metric Units
Average Acceleration ft/s2
Average Deceleration ft/s2
Characteristic
Accelerationft/s2
Kinetic Intensity mi-1
Average Time of a Stop s
Fractions in
Accel./Decel-Speed Bins%
Fractions in Grade Bins %
Mean Grade
Ascent/Descent%
4
100/%1
1
IdleVV idleno
2
~
aeroV
aki
Time, Distance, Energy, …
2. Integrated Bus Information System - IBISSome features are:
Searchable databases of transit vehicle emissions studies
Predictive emissions modeling toolsConstruction of virtual fleets
F.E., CO2, CO, NOx, HC, PM, NMHC
Diesel, CNG, Diesel-Electric Hybrid
Source: IBIS Presentation, July 20095
IBIS (Continued) Emissions data are
available on no more than 16 standard cycles + Idle cycle
Second-by-second data micro-trips new entries into the dataset
Chassis-dynamometer test data Correlations for fuel economy and
emissions Correction factors Current inputs:
(Average speed, Stops per Mile)
(Average speed, Percentage Idle)
(Average speed, Std. Dev. Speed)
(Average speed, Kinetic Intensity)
ΔSOC=0?
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3. Objectives1. To characterize transit bus operation
Correlations between the information available to transit agencies and the cycle metricsEvaluation of in-use routes and their properties
2. To evaluate the effects of driving cycle on the F.E., CO2 and NOx emissions of diesel-electric hybrids
Variety of driving conditionsRegression based modelAllow transit agencies to assess the best routes for the hybrids
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4. Methodology and Preliminary ResultsCharacterization of Transit Duty Cycles:
GPS logs of transit activityCollect information from transit agencyAnalysisDevelop correlations
Hybrid Bus Emissions ModelingMY 2007-2009 Allison Hybrid BusANN model for fuel, CO2, and NOx ratesDevelop hybrid controller / CalibrationSimulations / AnalysisDevelop correlations
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4.1. Characterization of Transit Duty CyclesGPS logs of in-use