A Method for Evaluating the Atmospheric Ozone Impact of Actual Vehicle Emissions

An exhaust gas quenching experiment was conducted to study the evolution of HC emissions and the extent of HC oxidation in the exhaust port and runner of a spark ignition engine. Fuel composition and engine parameter effects were of particular interest. The fuel set consisted of gasoline, several alkanes (methane, ethane, propane, n-butane, iso-octane), an alkene (ethene) and an aromatic (toluene); all fuel composition experiments were completed at a light load condition. The engine parameter set included engine speed, load, spark timing, equivalence ratio and coolant temperature; experiments involved mostly single parameter variations about a light load condition.The cylinder-exit HC emissions varied significantly over the set of fuels tested. There was no significant fuel dependency in the percentage of HC oxidation in the exhaust port/runner system, which ranged from 35 to 45%. A substantial portion of the oxidation occurred in the exhaust port. Speciated HC emissions identified unburned fuel as the major cylinder-exit species. The unburned fuel contribution ranged from 80 to 95% for methane, ethene and toluene and from 40 to 70% for the non-methane alkane fuels.Changes in the species distributions for the non-methane alkane fuels were observed in both the port and runner. Alkenes, the most reactive species in the formation of photochemical smog, were the dominant non-fuel species. Hence, the benefit of HC oxidation was accompanied by an increase in photochemical reactivity.Independent increases in engine speed and load produced decreases in the percentage of HC oxidation in the exhaust port/runner system. Higher temperatures due to spark retard increased HC oxidation from approximately 38% at MBT to approximately 53% at 12 degrees retard. Fuel lean conditions yielded higher oxidation levels (42%) than did fuel rich conditions (27%) due to the 02 availability. There was negligible change in oxidation level over the coolant temperature range tested.

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“…Optimum quench gas flow rates for 1500 and 2500 based on their reactivity in forming photochemical smog in the atmosphere [2].…”

Section: List Of Figuresmentioning

confidence: 99%

“…Alkenes and aldehydes have a much higher smog forming potential than do alkanes. From the species distributions, combined ozone reactivity factors [2] were calculated for the cylinder, port and runner exit HC emissions using the maximum incremental reactivity values proposed by the California Air Resources…”

Section: Species Distributionmentioning

confidence: 99%

Hydrocarbon oxidation in the exhaust port and runner of a spark ignition engine

Drobot

Cheng

Trinker

et al. 1994

Combustion and Flame

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“…In this paper, the estimation of ozone forming potential employed Lowi and Carter's MIR method [34] and Carter reactivity database (version 1994) [35]. Eqs.…”

Section: Methodsmentioning

confidence: 99%

Effects of engine misfire on regulated, unregulated emissions from a methanol-fueled vehicle and its ozone forming potential

Wang

Zhang

et al. 2016

Applied Energy

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“…Catalysts must be formulated which oxidize formaldehyde to C0 2 and H 2 0. Formaldehyde is especially undesirable due to its high photochemical reactivity (6). It is also a lacrimator and a known carcinogen.…”

Section: Catalytic Approaches For Meeting the Hc Control Challengementioning

confidence: 99%

Catalyst Technologies To Meet Future Emission Requirements for Light-Duty Vehicles

Summers

Silver

1992

ACS Symposium Series

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A Method for Evaluating the Atmospheric Ozone Impact of Actual Vehicle Emissions

Cited by 56 publications

References 4 publications

Hydrocarbon oxidation in the exhaust port and runner of a spark ignition engine

Hydrocarbon oxidation in the exhaust port and runner of a spark ignition engine

Effects of engine misfire on regulated, unregulated emissions from a methanol-fueled vehicle and its ozone forming potential

Catalyst Technologies To Meet Future Emission Requirements for Light-Duty Vehicles

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