The Effect of Driving Conditions and Ambient Temperature on Light Duty Gasoline-Electric Hybrid Vehicles (2): Fuel Consumption and Gaseous Pollutant Emission Rates

Christenson, Martha; Loiselle, Aaron; Karman, Deniz; Graham, Lisa

doi:10.4271/2007-01-2137

Cited by 16 publications

(24 citation statements)

References 4 publications

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“…For the hybrid vehicle only, the number of ICE restarts and the percentage of the city driving time when the ICE was off were also calculated (Percent Off, Table 3). Most ICE percent off times were comparable to those observed by Christenson et al for two other hybrid vehicles tested on a dynamometer (percent off from 0% to 20% for Prius and Ford Escape at low temperature (−18°C) and increased up to 66% or 55%, respectively, for tests conducted at 20°C) (8).…”

Section: Summary Of Datasupporting

confidence: 84%

“…However, vehicle emissions tests, typically performed under idealized lab conditions, are not wholly representative of the variability and emissions levels associated with real-world vehicle operating conditions. This study is part of a larger project initiated to better understand emissions from vehicles under real-world, on-road driving temperature of −18°C (8). An unexpected result of this study was the magnitude of the hybrid vehicle particle number emission rate when the engine restarted after the periods of electric-drive-only operation.…”

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confidence: 97%

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Onboard, Real-World Second-by-Second Particle Number Emissions from 2010 Hybrid and Comparable Conventional Vehicles

Robinson

Holmén

2011

Transportation Research Record: Journal of the Transportation R

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Despite hybrid-electric vehicles becoming more prominent in the on-road light-duty vehicle fleet, few studies have evaluated their real-world particle emissions. Hot-stabilized tailpipe particle number concentrations, emission rates, and number distributions emitted from two 2010 Toyota Camry vehicles—one hybrid and one conventional—were quantified during city driving in Burlington, Vermont, at ambient temperatures between −5°C and 9°C with the University of Vermont total onboard tailpipe emissions measurement system. Across replicate real-world runs, the average total cumulative particle number (3- to 3,000-nm particle diameter) emission rates measured for the hybrid vehicle were two times higher than that of the conventional vehicle, despite the hybrid vehicle's internal combustion engine being off 16% to 57% of the run duration. Average second-by-second number distributions for the conventional vehicle had three particle modes (10, 50, and 400 nm), whereas the broader hybrid vehicle distributions had two distinct modes (50 and 400 nm) with shoulders at 10 and 20 nm. These distributions changed little over the route for a given vehicle type. The unexpected higher particle number emission rates from the hybrid, and possibly the differences in number distributions, may be explained by an observed pattern of internal combustion engine restarts under stop-and-go driving that resulted in extreme particle emission rates up to 3.5 × 1010 (number per second) at every engine restart. The hybrid restart behavior resulted in high particle number emissions localized primarily at intersections. More detailed study is needed on different hybrid vehicle designs to determine the broader significance of the observed particle emission patterns.

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Section: Summary Of Datasupporting

confidence: 84%

mentioning

confidence: 97%

Onboard, Real-World Second-by-Second Particle Number Emissions from 2010 Hybrid and Comparable Conventional Vehicles

Robinson

Holmén

2011

Transportation Research Record: Journal of the Transportation R

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“…The cold engine start generally affects both fuel consumption and emissions of a vehicle [54]. Also, the ambient temperature of the test cell can affect the fuel consumption [55] and emissions [56] so the temperature in the test cell is maintained at 22.5 °C (72.5°F) average. The relative humidity is also controlled between 43.1 % and 47.9 % as shown in Table 5.1.…”

Section: Methodsmentioning

confidence: 99%

Vehicle Inertia Impact on Fuel Consumption of Conventional and Hybrid Electric Vehicles Using Acceleration and Coast Driving Strategy

Lee

Nelson

Lohse-Busch³

2009

SAE Technical Paper Series

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In the past few years, the price of petroleum based fuels, especially vehicle fuels such as gasoline and diesel, has been increasing at a significant rate. Consequently, there is much more consumer interest related to reducing fuel consumption for conventional vehicles and hybrid electric vehicles (HEVs) than in the past.The goal of many competitions and challenges held in North America and Europe is to achieve extremely low fuel consumption. A possible strategy to reduce fuel consumption is to use the vehicle's fuel converter such as an engine to accelerate the vehicle to a high speed and coast to a lower speed with the engine off. This method will reduce fuel flow to zero during the coast phase. Also, the vehicle uses higher power engine load to accelerate to the upper vehicle speed in a limited time, thus increasing the engine brake thermal efficiency. This strategy is known as "pulse and glide" or "burn and coast" in some references.In this study, the "pulse and glide" (PnG) method is first applied to a conventional vehicle to quantify the fuel consumption benefits when compared to steady speed conditions over the same distance. After that, an HEV is used as well to investigate if a hybrid system can further reduce fuel consumption with the proposed strategy. Note that the HEV used in this study has the advantage that the engine can be automatically shut off below a certain speed (~40 mph) at low loads, however a driver must shut off the engine manually in a conventional vehicle to apply this driving strategy.iii In this document, three preliminary results of the PnG driving strategy are presented; (1) improved fuel economy for a conventional vehicle from a simple spread sheet model, (2) improved fuel economy for an HEV from a dynamic vehicle simulation model (the Powertrain Analysis Toolkit (PSAT)) and (3) improved fuel economy for an HEV from vehicle testing at Argonne National Laboratory (ANL), all compared to steady speed conditions. The preliminary results show that the impact of engine load and kinetic energy stored in vehicle inertia is significant for fuel consumption using a PnG driving strategy compared to steady speed driving at the same average speed case. Especially, fuel economy can be improved at low speed range and higher acceleration because the aerodynamic drag force is smaller at low speed and the engine is running in a more efficient region for a short period of time respectively. In the last section, proposed directions of research are addressed based on the preliminary results.iv

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“…Increases in engine load increase PN emissions from SI engines across all engine sizes (20,21). Under dynamometer testing, HEVs and CVs have shown similar emissions patterns for criteria pollutants (hydrocarbons and nitrogen oxides) under heavy engine loading, with emissions rates increasing during acceleration and at high speeds (22).…”

Section: Factors Affecting Tailpipe Particulate Emissionsmentioning

confidence: 93%

Characterization of Real-World Particle Number Emissions during Reignition Events from a 2010 Light-Duty Hybrid Electric Vehicle

Conger

Holmén

2015

Transportation Research Record: Journal of the Transportation R

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Despite the increasing popularity of hybrid electric vehicles (HEVs), few studies have compared the real-world particle emissions of HEVs from internal combustion engine (ICE) reignition events with that of a conventional vehicle (CV) during real-world driving. Reignition events occur under unstable combustion conditions and frequently result in particle number (PN) emission rates (PNERs) that exceed those for stabilized engine operation. Tailpipe PNERs from a CV and an HEV 2010 Toyota Camry were quantified on a 32-mi route over rural, urban, and freeway roadways in Chittenden County, Vermont, with the total onboard tailpipe emissions measurement system. This study directly compared the CV and HEV PNERs and characterized the operation of the HEV in a new HEV ICE operating mode framework. Mean PNER for reignition events (7.19 pM 11.8 × 1010 particles/s) were on average four times greater than for stabilized HEV operation (1.79 ± 3.99 × 1010 particles/s). Under urban, rural, and freeway driving, HEV reignition event operation accounted for 58.7%, 44.6%, and 5.0%, respectively, of the total PN inventory. Mean HEV PNER was 1.8 times greater than that of the CV in urban driving, while under freeway driving, where the two vehicles operated similarly, average CV PNER was 2.4 times greater than that of the HEV. The data show that the typical fuel consumption benefits of HEVs in urban driving are associated with a trade-off in PN emissions. The HEV ICE operating behavior has implications for the spatial distribution of PN hot spots as well as the associated microscale modeling of alternative vehicle technology emissions.

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The Effect of Driving Conditions and Ambient Temperature on Light Duty Gasoline-Electric Hybrid Vehicles (2): Fuel Consumption and Gaseous Pollutant Emission Rates

Cited by 16 publications

References 4 publications

Onboard, Real-World Second-by-Second Particle Number Emissions from 2010 Hybrid and Comparable Conventional Vehicles

Onboard, Real-World Second-by-Second Particle Number Emissions from 2010 Hybrid and Comparable Conventional Vehicles

Vehicle Inertia Impact on Fuel Consumption of Conventional and Hybrid Electric Vehicles Using Acceleration and Coast Driving Strategy

Characterization of Real-World Particle Number Emissions during Reignition Events from a 2010 Light-Duty Hybrid Electric Vehicle

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