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Technical Paper

Effect of Engine Design/Control Parameters and Emission Control Systems on Specific Reactivity of S.I. Engine Exhaust Gases

1995-02-01
950807
In 1994, the California Air Resources Board implemented low-emission vehicle (LEV) standards with the aim of improving urban air quality. One feature of the LEV standards is the increasingly tighter regulation of non-methane organic gases (NMOG), taking into account ozone formation, in addition to the existing control of non-methane hydrocarbons (NMHC). Hydrocarbons and other organic gases emitted by S.I. engines have been identified as a cause of atmospheric ozone formation. Since the reactivity of each chemical species in exhaust emissions differs, the effect on ozone formation varies depending on the composition of the exhaust gas components. This study examined the effect of different engine types, fuel atomization conditions, turbulence and emission control systems on emission species and specific reactivity. This was done using gas chromatographs and a high-performance liquid chromatograph to analyze exhaust emission species that affect ozone formation.
Technical Paper

Performance and Exhaust Emissions of Nissan FFV NX Coupe

1992-02-01
920299
The FFVs under study operates on either M85 or M0 or any mixture of the two. Nissan has been actively conducting reseach and development on flexible fuel vehicles (FFVs) to explore the possibilities for long-range energy conservation and air quality improvement. The engine converted for use in these FFVs is a 1.6 liter, four-cylinder in-line powerplant, with dual overhead camshafts and four valves per cylinder. It employs the Nissan Variable valve timing Control System (NVCS). The fuel sensor for measuring the methanol concentration in the fuel has been improved both in terms of accuracy and durability. This paper describes the engine performance and exhaust emission levels (formaldehydes unburned methanol and HC emissions) obtained with both M85 and M0.
Technical Paper

Effects of Exhaust Emission Control Devices and Fuel Composition on Speciated Emissions of S.I. Engines

1992-10-01
922180
Hydrocarbons and other organic materials emitted from S.I. engines cause ozone to form in the air. Since each species of organic materials has a different reactivity, exhaust components affect ozone formation in different ways. The effects of exhaust emission control devices and fuel properties on speciated emissions and ozone formation were examined by measuring speciated emissions with a gas chromatograph and a high-performance liquid chromatograph. In the case of gasoline fuels, catalyst systems with higher conversion rates such as close-coupled catalyst systems are effective in reducing alkenes and aromatics which show high reactivities to ozone formation. With deterioration of the catalyst, non-methane organic gas (NMOG) emission increases, but the specific reactivity of ozone formation tends to decrease because of the increase in alkane contents having low MIR values.
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