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Technical Paper

Effects of Clean Fuels (Reformulated Gasolines, M85, and CNG) on Automotive Emissions

1992-10-01
922380
With the aim of improving the air quality in large cities, the California Air Resources Board (CARB) has stipulated that non-methane organic gas (NMOG) composed of carbon numbers from C1 to C12 must be reduced for vehicle categories designated as Transitional Low Emission Vehicles (TLEVs), Low Emission Vehicles (LEVs), Ultra low Emission Vehicles (ULEVs), and Zero Emission Vehicles (ZEVs). Although considerable research work has been done on this issue to date, the entire picture is still not clear. Studies done by the authors have been aimed at providing a better understanding of the potential for reducing automotive tailpipe emissions by using several clean fuel candidates. The major questions of concern are the extent to which emissions of certain species can actually be reduced and what fuel can provide the best performance under a reduced NMOG condition.
Technical Paper

Improvement of Cold Startability Running on M85 Spark Ignition Engine

1992-02-01
920293
Cold startability is one problem common to methanol vehicles because of methanol's low volatility. This study describes two necessary conditions for cold starting at -30°C: installing a cold start injector in the intake manifold and raising the Reid Vapor Pressure to 75.5 kPa. The cold start injector atomizes fuel to a 90- μ m average diameter in the intake ports and improves the mixture distribution at a temperature as cold as -30°C. Moreover, accomplishing cold starting requires that the indicated mean effective pressure of 686 kPa and above must be sustained until fast idling is reached.
Technical Paper

Stabilized Combustion in a Spark Ignited Engine through a Long Spark Duration

1985-02-01
850075
An investigation has been done on the relationship between spark ignition characteristics and combustion stability in a gasoline engine. The spark discharge parameters examined were the spark current, energy, and duration. It has been found that lengthening the spark discharge duration is particularly effective in achieving stabilized combustion. A longer spark duration provides a continued supply of electric energy as kinetic energy to the mixture around the spark gap. The analytical results of a constant volume combustion chamber test verify that a longer spark duration promotes flame initiation and makes reliable flame propagation possible. The length of the spark duration is regarded as the period from ignition to the onset of combustion pressure rise. The results of a combustion pressure analysis reveal that the spark duration must be longer than the heat release delay.
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