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

Robinson, Mitchell; Holmén, Britt A.

doi:10.3141/2233-08

Cited by 17 publications

(16 citation statements)

References 18 publications

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“…On the Artemis cycle the hybrid vehicle shows PN emissions higher than the CNG one, in agreement with Schreiber et al [21]. This unexpected result could be due to the frequent engine restart events that could be related to either lower exhaust and catalyst temperatures or "quick start" fuel management strategies [22] [23].…”

Section: Resultssupporting

confidence: 80%

Gaseous and Particulate Exhaust Emissions of Hybrid and Conventional Cars over Legislative and Real Driving Cycles

Costagliola¹,

Prati

Mariani³

et al. 2015

EPE

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Road transport exhaust emissions represent the main sources of atmospheric pollution in urban areas, due to the growing number of circulating vehicles and travelled distances. In order to reduce this pollution source, stricter emission standards are periodically set by governments throughout the world. Consequently, the concentrations of gaseous pollutants and particulate mass to be measured during type-approval tests of new vehicles are becoming progressively lower; moreover from 2011, diesel cars have to comply with particle number limit. In order to assess emission levels of different technology vehicles and investigate the use of a particulate number measurement technique at the exhaust of very low-emitting vehicles, an experimental activity was carried out on three in-use vehicles: a diesel car equipped with a particulate trap (DPF), a hybrid gasoline-electric car and a bi-fuel passenger car fuelled with compressed natural gas (CNG). Cold and hot gaseous and particulate emission factors and fuel consumption were measured during the execution of real and regulatory driving cycles on a chassis dynamometer. Particulate was characterized in terms of mass only for the diesel car and of particle number for all vehicles. The emissions measured over the NEDC show that all three vehicles comply with their standard limits, except CO for CNG passenger car and NOx for diesel car. Cold start influences CO and HC emissions and fuel consumption for all the tested vehicles and in particular for the hybrid car. The real driving cycle is the most critical pattern for the emissions of almost all pollutants. During constant speed tests, the emissions of particles of hybrid car are an order of magnitude lower than those of the CNG car.

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Section: Resultssupporting

confidence: 80%

Gaseous and Particulate Exhaust Emissions of Hybrid and Conventional Cars over Legislative and Real Driving Cycles

Costagliola¹,

Prati

Mariani³

et al. 2015

EPE

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“…Little if any direct investigation of reignition events has been conducted under real-world driving conditions. Reignition events have been spatially associated with urban driving, particularly at intersections where ICE-off operation under low speed and load is followed by an increase in power demand (7). There is a necessary association between periods of ICE off and reignition events, yet the ICE-off events are dependent on many variables.…”

Section: Factors Affecting Hev Reignition Eventsmentioning

confidence: 99%

“…Airborne particulate matter 2.5 µm and smaller (PM 2.5 ) is a regulated criteria pollutant under the National Ambient Air Quality Standards (16). Inconsistencies arise with regulation of PM based solely on mass in tailpipe emissions, as there is a general lack of correlation between particle number (PN) and particle mass in vehicle exhaust (7,14). Although particles in the nanoparticle mode (diameter less than 50 nm) constitute 90% or more of the total PN, they only account for between 1% and 20% of total particle mass in spark-ignited engine exhaust (14).…”

Section: Factors Affecting Hev Reignition Eventsmentioning

confidence: 99%

“…The effects of HEV ICE on-off cycling during low-speed driving conditions have been shown to result in a twofold increase in highemission events (HEEs), or PN emission rates (PNER, in particles per s) above the 90th percentile, compared with a CV driven along the same route (7). Robinson and Holmén (7) found that during urban driving, 85% of all HEV HEEs occur as a result of reignitions.…”

Section: Pn Emissions From Hev Reignition Eventsmentioning

confidence: 99%

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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 PM and PN of a GDI engine are about 35 and 22 times higher, respectively, than those of a PFI engine. 12,13 Furthermore, Robinson and Holmén 14 observed unexpectedly high particulate emissions from a GDI engine in a hybrid vehicle. The authors recognized a pattern in which extreme particulate emissions were detected every time the engine was restarted from the engine stop.…”

Section: Introductionmentioning

confidence: 98%

Analysis of the relationship between particle number and fuel cutoff in a single-cylinder gasoline direct injection engine

Song

Choi

2020

Proceedings of the Institution of Mechanical Engineers, Part D:

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This study investigates the effects of fuel cutoff on particle number in a single-cylinder wall-guided gasoline direct injection engine. Various durations of fuel cutoff and change in load and engine stop were tested, and the in-cylinder pressure, particle number, and NO x emissions were measured. The change in in-cylinder temperature during combustion stop was calculated using the in-cylinder pressure and the ideal gas law. Experimental results showed that as the fuel cutoff duration increased, the particle number increased significantly when combustion resumed. For the injection timing before top dead center 330°, the particle number, which was 600 × 103 #/cm3 under the continuous combustion condition, increased to 6700 × 103 #/cm3 after 30 s of fuel cutoff. Both the fuel cutoff and engine stop showed enormous amount of particle number when combustion restarted. A major factor that increased particle number was the temperature reduction of piston during the combustion stop. The peak in-cylinder temperature decreased by 38 K during 30 s of motoring, which was induced by the temperature drop of the piston. Therefore, in terms of particulate emissions, it is more advantageous to lower the engine load than to stop combustion: the piston surface remains hot during load reduction. In addition, it is recommended to change the engine load slowly to reduce the particle number emissions. In this study, the rapid load change from indicated mean effective pressure of 0.25 to 0.55 MPa showed 7% higher particle number emissions than the gentle load change. On the contrary, NO x was reduced because none was generated during combustion stop. However, the fuel cutoff would increase NO x in gasoline vehicles because the oxygen in the unburned air would significantly reduce the conversion efficiency of a three-way catalytic converter. It is especially worth investigating the reason for the increase in emissions because it is easy to think that all kinds of emissions will be reduced if fuel is not burned.

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

Cited by 17 publications

References 18 publications

Gaseous and Particulate Exhaust Emissions of Hybrid and Conventional Cars over Legislative and Real Driving Cycles

Gaseous and Particulate Exhaust Emissions of Hybrid and Conventional Cars over Legislative and Real Driving Cycles

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

Analysis of the relationship between particle number and fuel cutoff in a single-cylinder gasoline direct injection engine

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